scholarly journals Models to estimate longitudinal compressive strength of Brazilian hardwood based on apparent density

BioResources ◽  
2021 ◽  
Vol 16 (1) ◽  
pp. 1373-1381
Author(s):  
Francisco Antonio Rocco Lahr ◽  
Felipe Nascimento Arroyo ◽  
Edson Fernando Castanheira Rodrigues ◽  
João Paulo Boff Almeida ◽  
Vinicius Borges de Moura Aquino ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Apparent Density ◽  
Regression Models ◽  
Physical And Mechanical Properties ◽  
Natural Material ◽  
Linear Regression Models ◽  
Linear Polynomial ◽  
Best Fit ◽  
Brazilian Standard ◽  
Large Research

As wood is an orthotropic and natural material, there are several properties required for its use in civil construction. The apparent density has been used to estimate physical and mechanical properties of wood, as it is easy to determine experimentally, unlike other determinations, which involve the use of equipment available only in large research centers. Using the Brazilian standard ABNT NBR 7190 and linear and non-linear regression models, this research aimed to evaluate their accuracy in estimating the compressive strength parallel to the fibers (fc0) as well as their characteristic value (fc0,k). This study considered 72 tropical wood species from native forests that were divided into the 4 strength classes of this standard. For the set formed by all species, the linear polynomial model was the best fit, resulting in a determination coefficient of just over 70%.

scholarly journals PHYSICAL AND MECHANICAL CHARACTERIZATION OF PLANCHONELLA PACHYCARPA WOOD SPECIES FOR USE IN STRUCTURAL PURPOSE

Wood Research ◽  
2021 ◽  
Vol 66 (2) ◽  
pp. 267-276
Author(s):  
Vinicius Borges De Moura Aquino ◽  
Marcus Vinicius Pereira De Freitas ◽  
Claudia Queiroz De Vasconcelos ◽  
João Paulo Boff Almeida ◽  
Felipe Nascimento Arroyo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Apparent Density ◽  
Wood Species ◽  
Regression Models ◽  
Physical And Mechanical Properties ◽  
Stiffness Properties ◽  
Longitudinal Elastic Modulus ◽  
Structural Purpose ◽  
Brazilian Standard

This research aimed to characterize the wood species Goiabão (Planchonella pachycarpa), following the precepts set forth in the Brazilian standard ABNT NBR 7190, as well as to evaluate the possibility of estimating physical and mechanical properties, using the analysis of variance (ANOVA) as a function of apparent density, and also to estimate the stiffness properties as a function of the respective strength property. The physical and mechanical properties were considered adequate for the use of this wood for structural purposes, being classified in class C40. According to the results of the regression models, it is possible to estimate the tensile strength parallel to the fibers as a function of the apparent density. It was also possible to estimate the longitudinal elastic modulus in the compression parallel to the fibers as a function of the compressive strength parallel to the fibers.

scholarly journals The Utilization of Waste Marble Dust as a Cement Replacement in Air-Cured Mortar

2019 ◽  
Vol 11 (8) ◽  
pp. 2215 ◽  
Author(s):  
Nadhir Toubal Seghir ◽  
Mekki Mellas ◽  
Łukasz Sadowski ◽  
Aleksandra Krolicka ◽  
Andrzej Żak ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Apparent Density ◽  
Ordinary Portland Cement ◽  
Microstructural Analysis ◽  
Physical And Mechanical Properties ◽  
Cement Replacement ◽  
Marble Dust ◽  
Different Levels ◽  
Local Laboratory ◽  
Scanning Electron

The aim of this study is to assess the possibility of utilizing waste marble dust (WMD) as a partial cement substitution in air-cured mortar (ACM). Three different levels of cement replacement were analyzed: 5%, 10% and 15% by cement weight. The specimens were manufactured in a local laboratory at an air temperature of 22 ± 2 °C and a humidity equal to 20 ± 1%. The chemical and physical properties of ordinary Portland cement and WMD has been found to be the most crucial parameters. A variety of macroscopic tests, such as apparent density, porosity and compressive strength, were proposed in order to explain the effect of utilizing the WMD on the ACM. To confirm the results of the macroscopic properties, thorough microstructural analysis using scanning electron microscopy (SEM) was performed. The obtained results of this study indicate that replacing cement with WMD affects the physical and mechanical properties of air-cured mortar. The apparent density and compressive strength decrease while the porosity increases.

scholarly journals Assessment of spline functions for estimating growth curve parameters of FUNAABAlpha chickens

2020 ◽  
Vol 46 (5) ◽  
Author(s):  
H. A. Bashiru ◽  
S. O. Oseni ◽  
L. A. Omadime
Keyword(s):  
Regression Models ◽  
Selection Criteria ◽  
Goodness Of Fit ◽  
Information Criterion ◽  
Regression Coefficients ◽  
Spline Functions ◽  
Linear Regression Models ◽  
Male And Female ◽  
Spline Models ◽  
Best Fit

The objective of this study was to fit four spline linear regression models to describe the growth of FUNAAB-Alpha Chickens (FAC). Body weight records of 300 FAC raised from day old till the 20th week were used to fit spline models of 3 (SP3), 4 (SP4), 5 (SP5) and 6 knots (SP6) using the REG procedure of SAS®. The data were first plotted to determine the most appropriate location of knots and they were placed at 4th, 10 th and 16 th week of age for SP3; 4th, 8th, 12th and 16th week for SP4; 4th, 7th, 10th, 14th and 18th week for SP5 and 3rd, 6th, 9th, 12th, 15 th and 18 th week for SP6, respectively. The hatch weight predicted by SP3 was observed to be highest while SP6 predicted the lowest hatch weight for male and female FAC. Regression coefficients ranged from -38.47 to 47.46 and -39.40 to 40.47 for the male and female, respectively. For all the models, the highest magnitude of these coefficients were estimated at early ages after hatching (at 3 to 10 weeks of age). Based on Bayesian Information Criterion (BIC) and Akaike Information Criterion (AIC) as the goodness-of-fit selection criteria, SP3 had the lowest value for AIC and BIC for male FAC while SP4 had the lowest value of AIC and BIC for the female FAC. It was concluded that spline models of lower knots (SP3 and SP4) were the best fit to describe the growth of male and female FAC respectively, and that growth rate at early stages of life of FAC may be good predictors of later growth performance.

016 Associations between Circadian Melatonin and Temperature Amplitudes during Constant Routine

SLEEP ◽  
2021 ◽  
Vol 44 (Supplement_2) ◽  
pp. A8-A8
Author(s):  
Katrina Rodheim ◽  
Christoper Jung ◽  
Kenneth Wright
Keyword(s):  
Individual Differences ◽  
Regression Models ◽  
Signal To Noise Ratio ◽  
Large Individual ◽  
Linear Regression Models ◽  
Harmonic Model ◽  
Circadian Phase ◽  
Best Fitting ◽  
Harmonic Regression ◽  
Best Fit

Abstract Introduction Circadian amplitude measures the strength or robustness of a rhythm and changes in amplitude may have implications for health. Large individual differences in melatonin amplitude are recognized. Here we aimed to determine the strength of relationships between melatonin and the core body (CBT) and distal-proximal skin temperature gradient (DPG) amplitudes during a constant routine protocol. Additionally, we determined the best fitting harmonic model for the DPG circadian rhythm. Methods 17 young healthy adults [13 males (22.3±3.9yr;mean±SD)] completed a 28-hr constant routine protocol after maintaining 8h habitual sleep schedules for one week at home. Endogenous circadian amplitudes of melatonin and CBT were fit with standard three- and dual-harmonic linear regression models, respectively. The DPG amplitude was analyzed with both dual and three-harmonic regression models to determine which model produced the best fit. Results The DPG was best fit by a three-harmonic regression model with significantly lower standard deviation and higher signal-to-noise ratio compared to the 2-harmonic model (both p<0.05) as well as by visualization of the fitted curves. Melatonin, CBT and DPG amplitudes were not found to be associated with each other during constant routine (all r<0.37; all p>0.10). Conclusion While it is common for melatonin and body temperature circadian phase estimates to be used interchangeably, non-significant findings for associations between circadian amplitudes of melatonin, CBT and DPG indicate that these markers may not provide similar information about circadian amplitude. Further, research is needed to explore possible associations between individual differences in melatonin, CBT and DPG amplitudes with other physiological and behavioral outcomes to determine which measure(s) of circadian amplitude may be functionally relevant. Support (if any) NIH R01 HL081761

Effects of olive oil on physical and mechanical properties of ceramic waste-based geopolymer foam

2019 ◽  
Vol 39 (3-4) ◽  
pp. 111-118 ◽  
Author(s):  
Narumon Lertcumfu ◽  
Kannikar Kaewapai ◽  
Pharatree Jaita ◽  
Tawee Tunkasiri ◽  
Somnuk Sirisoonthorn ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Water Absorption ◽  
Olive Oil ◽  
Apparent Density ◽  
Pore Formation ◽  
Physical And Mechanical Properties ◽  
Total Porosity ◽  
Calcined Clay ◽  
Ceramic Waste ◽  
Geopolymer Composites

The present study concentrated on porous geopolymer composites (between calcined clay and metakaolin) using hydrogen peroxide as a pore generation agent. To reduce as well as recycle the waste from a factory, calcined clay waste was used as starting material. The geopolymer was synthesized via a geopolymerization method by a reaction with an alkaline solution, using the ceramic waste and metakaolin as raw materials. Different amount of olive oil (0–15 wt%) were added to the samples. The olive oil affected the pore formation of the geopolymers. The effects of olive oil, a surfactant, on the properties of the geopolymer composites were investigated. Apparent density and compressive strength of the samples tended to decrease with the additive, while water absorption and total porosity had the opposite effect. However, a variation in the apparent density and water absorption values was observed, due to the formation of closed pores in the samples. The trend of compressive strength value was related with total porosity. A model for pore formation was proposed in this work. The results suggest that this material can be used as a geopolymer foam.

scholarly journals PHYSICAL-MECHANICAL PROPERTIES OF BRIQUETTES PRODUCED FROM CHARCOAL FINES AND WASTE OF Pinus spp.

FLORESTA ◽  
2018 ◽  
Vol 48 (4) ◽  
pp. 513 ◽  
Author(s):  
André Tarcizo de Oliveira Vieira ◽  
Alexandre Miguel do Nascimento ◽  
Azarias Machado de Andrade ◽  
Ananias Francisco Dias Júnior
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Apparent Density ◽  
Physical And Mechanical Properties ◽  
Wood Waste ◽  
Particle Sizes ◽  
Maize Starch ◽  
Wood Shavings ◽  
Pinus Spp

The objective of this research was to evaluate the physical and mechanical properties of briquettes produced with charcoal fines and waste of Pinus spp (sawdust and wood shavings). For the production, the charcoal fines of two particle sizes (less than and greater than 5 mm) were mixed with each type of wood waste of Pinus spp in the proportions of 5, 10, 15, and 20%. Then, the mixtures were compacted under the pressure of 55 kgf.cm-2 in a piston briquetter. As binder, 8% gelatinized maize starch was used. Tests were carried out on the briquettes in order to determine the apparent density, compressive strength, and friability index. Briquettes with the highest densities and compressive strengths were produced with the two lowest proportions of wood waste of Pinus spp (5 and 10%). The use of the charcoal fines combined with sawdust or wood shavings of Pinus spp is recommended for the production of briquettes with good physical and mechanical properties.

scholarly journals Serbian heavy clays behavior: Application in rough ceramics

2013 ◽  
Vol 67 (5) ◽  
pp. 811-822 ◽  
Author(s):  
Milica Arsenovic ◽  
Lato Pezo ◽  
Zagorka Radojevic ◽  
Slavka Stankovic
Keyword(s):  
Compressive Strength ◽  
Regression Models ◽  
Statistical Difference ◽  
Raw Materials ◽  
Absorption Capacity ◽  
Linear Regression Models ◽  
S Curve ◽  
Plasticity Coefficient ◽  
Post Hoc ◽  
Mineralogical Compositions

This study is focused on the behavior of five new deposits of heavy clays from Serbia, with the aim to evaluate their potential suitability as raw materials in rough ceramic applications. The Pfefferkorn plasticity coefficient (PC) and drying susceptibility using Bigot?s curve were measured for each raw sample. Thermodilatometric analysis (TDA) showed the behaviour of dry products during firing. Samples groups were fired in the range of 850?C - 1000?C. Water absorption capacity (WAC) and compressive strength (CS) were done in order to characterize clays after firing. Linear regression models were used to fit the results. Mathematical tools were used to determine statistical difference of major oxides content, shaping moist and compressive strength of dry laboratory products, using post-hoc Tukey`s HSD test. The chemical and mineralogical compositions of samples do not differ considerably, but their possible application does. All studied clays seem to be easily adaptable to a correct brick making process.

scholarly journals Influence of Basalt Fiber on the Physical and Mechanical Properties of Aerated Ceramsite Concrete

2020 ◽  
Vol 44 (6) ◽  
pp. 427-432
Author(s):  
Yonghe Yao ◽  
Yanhong Wang ◽  
Jun Xu ◽  
Yajun Hu
Keyword(s):  
Mechanical Properties ◽  
Tensile Strength ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Apparent Density ◽  
Basalt Fiber ◽  
Volume Ratio ◽  
Physical And Mechanical Properties ◽  
Splitting Tensile Strength ◽  
Technical Performance

In order to improve the technical performance of Aerated Ceramsite Concrete (ACC) so that it could better meet the requirements of lightweight wallboards for prefabricated buildings, this study mixed 0%, 0.05%, 0.10%, 0.15% and 0.20% of the Basalt Fiber (BF) by volume ratio into the ACC of 100mm-thickness LC15 lightweight wallboards, and conducted experiments to test the apparent density, compressive strength, splitting tensile strength, and flexural strength on the 7d, 14d, and 28d of the experiment; then, the microstructure and failure forms of the BF-improved ACC material were observed and analyzed, and the results showed that adding BF can effectively improve the physical and mechanical properties of ACC, and the optimal BF content in the ACC of lightweight wallboards is 0.10%-0.15%.

scholarly journals Model-based Informal Inference

2017 ◽  
Vol 6 (5) ◽  
pp. 140
Author(s):  
Theodosia Prodromou
Keyword(s):  
Linear Regression ◽  
Instructional Practices ◽  
Linear Model ◽  
Regression Models ◽  
Linear Models ◽  
Linear Regression Models ◽  
Journal Paper ◽  
Support Students ◽  
Best Fit ◽  
Informal Inference

Following recent scholarly interest in teaching informal linear regression models, this study looks at teachers’ reasoning about informal lines of best fit and their role in pedagogy. The case results presented in this journal paper provide insights into the reasoning used when developing a simple informal linear model to best fit the available data. This study also suggests potential in specific aspects of bidirectional modelling to help foster the development of robust knowledge of the logic of inference for those investigating and coordinating relations between models developed during modelling exercises and informal inferences based on these models. These insights can inform refinement of instructional practices using simple linear models to support students’ learning of statistical inference, both formal and informal.

Sign in / Sign up

Export Citation Format

Share Document