Energetic investigation of the fatigue of wood

Holzforschung ◽  
2014 ◽  
Vol 68 (7) ◽  
pp. 843-848 ◽  
Author(s):  
Yasutoshi Sasaki ◽  
Ayaka Oya ◽  
Mariko Yamasaki
Keyword(s):  
Fatigue Limit ◽  
Static Strength ◽  
Loading Conditions ◽  
Static Tests ◽  
Bending Fatigue ◽  
A Value ◽  
New Findings ◽  
Multiple Loading ◽  
The Mean ◽  
The Relationship

Abstract There are gaps in our knowledge regarding temporal changes in wood stability and mechanical properties in the context of wood durability. Energetic analyses have been performed in this study based on experimental results on the bending fatigue of wood under multiple loading conditions. New findings regarding the fatigue limit and fatigue life (Nf) are presented. The strain energy (SE) obtained from stress-strain envelopes until wood reaches its Nf is a value specific to wood species and static strength regardless of the loading conditions. This value is about 50% higher than the SE in static tests. The relationship between mean energy loss (EL) and stress level (SL) to the point of fatigue failure is bilinear, and the mean EL is closely related to Nf. Moreover, the SL – when mean EL approaches a specific value (∼1.10 kJ m-3 per cycle) as Nf approaches infinity – is considered to be the fatigue limit; the latter is estimated to be about 20–30% of static strength.

scholarly journals The Relationship Between Digital Egg Coloration and Egg Survival in Landlocked Fall Chinook

2018 ◽  
Vol 7 (1) ◽  
pp. 31
Author(s):  
Holiday Robley ◽  
Michael E. Barnes
Keyword(s):  
South Dakota ◽  
Chinook Salmon ◽  
Color Index ◽  
Oncorhynchus Tshawytscha ◽  
Egg Survival ◽  
A Value ◽  
The Mean ◽  
The Relationship ◽  
Egg Coloration

Digital color values were collected from the eggs of 128 spawns from individual landlocked fall Chinook salmon Oncorhynchus tshawytscha females from Lake Oahe, South Dakota, USA, in 2008, 2009, 2015 and 2016. For all spawns, the mean (SE) a* value, a measure of red-green chromaticness, was 10.99 (0.27), and ranged from 3.98 to 18.71. Mean (SE) b* (yellow-green) was 20.27 (0.32), and ranged from 9.28 to 28.50. Mean (SE) L* (white-black) was 20.73 (0.48), and ranged from 3.98 to 18.71. Egg total color index also showed considerable variation, with a mean (SE) of 23.05 (0.37) and range from 11.70 to 31.64. Egg survival to the eyed-stage was weakly, but significantly, correlated to b* (r = 0.206), L* (r = 0.185), Chroma (r = 0.211), and Entire Color Index (r = 0.211). Spawns with no egg survival had eggs with significantly lower a* values compared to spawns where at least some of the eggs survived to the eyed stage. L*, a*, b*, Chroma, and Entire Color Index varied significantly among the years, but Hue and egg survival to the eyed stage did not. The results of this study indicate a possible link between egg color and landlocked fall Chinook salmon egg survival, possibly due to differences in the diets of feral broodstock females or their ability to deposit bodily carotenoids in the developing eggs.

Relationship between Feedrate and Fatigue Life of Al7075-T6 Specimens before and after Shotpeening

2008 ◽  
Vol 580-582 ◽  
pp. 109-112 ◽  
Author(s):  
Hyoung Tae Kim ◽  
Ki Hoon Shin
Keyword(s):  
Fatigue Life ◽  
Loading Conditions ◽  
Mean Diameter ◽  
Before And After ◽  
Bending Stresses ◽  
The Mean ◽  
The Relationship

This paper presents a study on the relationship between feedrate and fatigue life of Al7075-T6 specimens before and after shotpeening. For this purpose, six groups of specimens, each of which consists of eight specimens, were first machined at six different feedrates (0.05, 0.10, 0.15, 0.20, 0.25, 0.30 mm/rev). Half of eight specimens in each group were then peened and the others remained un-peened. Next, the fatigue life was measured by using 4-point rotary bending machine. One observation was that the fast the feedrate was, the large the mean diameter of a specimen was. To apply the same bending stresses in all cases, different loading conditions were thus recalculated and applied to specimens based on their mean diameters. Finally, the effect of feedrate on the fatigue life was estimated by comparing twelve sets of specimens (six groups times two sets, peened and un-peened).

Operating Speed on Crest Vertical Curves with Limited Stopping Sight Distance

2000 ◽  
Vol 1701 (1) ◽  
pp. 25-31 ◽  
Author(s):  
Daniel B. Fambro ◽  
Kay Fitzpatrick ◽  
Charles W. Russell
Keyword(s):  
Operating Speed ◽  
Design Elements ◽  
Geometric Data ◽  
A Value ◽  
Sight Distance ◽  
The Mean ◽  
The Difference ◽  
Design Speed ◽  
Stopping Sight Distance ◽  
The Relationship

Horizontal and vertical elements of a highway are designed based on an assumed design speed. This concept was developed in the 1930s as a mechanism for designing rural alignments to permit most drivers to operate uniformly at their desired speed. In 1938, AASHO recognized that drivers select a speed influenced by the roadway environment instead of an assumed design speed. Recent research suggests that design speed is no longer the speed adopted by the faster group of drivers but that it has become a value used to establish the sharpness of horizontal and vertical design elements. The objective of this study was to establish the relationship between design and operating speeds for crest vertical curves with limited sight distance. Geometric data and 3,500 paired speeds (speeds at control and crest sections) were collected at 36 sites in 3 states. The results indicated that both the 85th percentile and the mean operating speeds were well above the inferred design speeds of the crest vertical curves for the range of conditions studied and that the lower the design speed the larger the difference between the 85th percentile speed and the design speed. The mean reductions in speed between the control and crest sections tend to increase as available sight distance is decreased; however, the reduction in speed is less than that suggested by current AASHTO criteria.

The ages of some African lepidolites determined from the 87 Rb- 87 Sr decay

1957 ◽  
Vol 146 (923) ◽  
pp. 257-269 ◽  
Keyword(s):  
North East ◽  
A Value ◽  
South West ◽  
Statistical Experiments ◽  
South West Africa ◽  
Single Determination ◽  
The Mean ◽  
Southern Rhodesia ◽  
Relationship Of ◽  
The Relationship

Using isotope dilution the ages of fourteen lepidolite hand samples representing eight different areas have been determined. Lepidolites from Pope’s Claim, Southern Rhodesia, Bikita, Southern Rhodesia and Alto Ligonha, Portuguese East Africa, were investigated in a series of statistical experiments and the ages and 95% confidence limits for the mean of the determinations are: Pope’s Claim ' A ' 2931 ± 63 million years, Pope’s Claim ' B ' 2955 ± 75 million years; Bikita ' A ' 2978 ± 43 million years, Bikita ' B ' 2961 ± 25 million years; Alto Ligonha ' A ' 533 ± 8·3 million years, Alto Ligonha ' B ' 528 ± 8·5 million years. Ḟurther samples from Bikita show ages ranging from 2830 to 3040 million years and all lying within the 95% confidence limit for a single determination. The Karibib area, South-West Africa, is dated from three separate samples as 600 ± 70 million years. The other ages determined are Hombola, Tanganyika (2990 ± 200 million years), Antelope Mine, Southern Rhodesia (2675 ± 150 million years), Tsarafara, Madagascar (652 ± 45 million years) and Mica Siding North-East Transvaal (2040 ± 150 million years). In these cases the uncertainty quoted covers the range of the determinations made. The relationship of these ages to ages determined using 87 Rb— 87 Sr decay elsewhere and to U—Pb ages for the same areas is discussed, and it is shown that for the Rhodesian shield a value of λ = 1·26 ± 0·04 x 10 -11 for 87 Rb decay would lead to agreement with the U-Pb ages.

scholarly journals Effect of Processing and Loading Conditions upon the Fatigue Behaviour of a Cf/Epoxy Laminate

2009 ◽  
Vol 18 (3) ◽  
pp. 096369350901800 ◽  
Author(s):  
Christos Koimtzoglou ◽  
Konstantinos G. Dassios ◽  
Costas Galiotis
Keyword(s):  
Fatigue Limit ◽  
Failure Modes ◽  
Matrix Material ◽  
High Stress ◽  
Fatigue Behaviour ◽  
Static Strength ◽  
Testing Conditions ◽  
The Matrix ◽  
The Mean ◽  
Loading Scheme

The current work reports on the tensile and fatigue behaviour of an autoclave-cured unidirectional carbon fibre reinforced epoxy-matrix laminate. The macromechanical properties of the composite are established under interrupted and uninterrupted, static and dynamic conditions at a maximum strain below the critical fatigue limit of the matrix material. The established S-N curve was used to calculate the endurance fatigue limit of the laminate as well as to record an increase in fatigue life of specimens tested at load levels lower than two standard deviations below the mean static strength of the material. The failure modes exhibited by the composite under all testing conditions were recorded and interpreted by means of the damage mechanisms that originate them. The results of interrupted testing showed that the combined effect of fatigue and residence at high stress levels for prolonged periods of time - conditions that simulate a realistic loading scheme- trigger premature fibre failure and thus specimen failure.

scholarly journals Perbandingan efektivitas penggunaan audio visual terhadap penurunan kecemasan anak selama perawatan gigi di TK Pertiwi dan TK Raudhatul Jannah Banda Aceh

2020 ◽  
Vol 2 (1) ◽  
pp. 108
Author(s):  
M. Erfin Febrian ◽  
Aulina Adami ◽  
Asnawi Abdullah
Keyword(s):  
Dental Care ◽  
Dental Treatment ◽  
Intervention Group ◽  
Cross Sectional Study ◽  
Cross Sectional ◽  
Test Analysis ◽  
A Value ◽  
The Mean ◽  
The Difference ◽  
The Relationship

Background: Anxiety in children about dental care is a problem that arises in children. This is because the dentist's perception and introduction to children does not start early.Objectives: This study aims to compare the effectiveness of the use of audio visuals on reducing children's anxiety during dental treatment at Pertiwi and Raudhatul Jannah Kindergarten in Banda Aceh.Methods: This study uses a cross-sectional study design which is a study conducted to find the relationship between the independent variables (risk factors) and the dependent variable anxiety in dental care. Sampling was done by purposive sampling with the criteria of children aged 5-6 old. The number of samples is 100 samples. Test analysis using the dependent t-test and was analyzed using the stata 14.Results: The results showed, the comparison between the first day and the second day showed a difference in the decrease in anxiety level with the child's anxiety score with intervention of 2.78 with a deviation of 1.379 while the second group without intervention had a decrease in the mean score of anxiety, which was 2.48 with a deviation of 1.455. The difference in the decrease in anxiety scores in children is 0.30. The results of the T-Dependent statistical test obtained a value of p= 0.001Conclusion: In other words, the results of this study can show differences in the level of anxiety in the intervention group with the group that did not use the audio visual intervention.

scholarly journals Comparison of Peripheral and Central Venous Pressures in Critically Ill Patients

2003 ◽  
Vol 31 (1) ◽  
pp. 34-39 ◽  
Author(s):  
C. Charalambous ◽  
T. A. Barker ◽  
C. S. Zipitis ◽  
I. Siddique ◽  
R. Swindell ◽  
...  
Keyword(s):  
Critically Ill ◽  
Critically Ill Patients ◽  
Accurate Estimate ◽  
Mean Difference ◽  
A Value ◽  
Actual Change ◽  
The Mean ◽  
A Prospective Study ◽  
The Relationship ◽  
Serial Measurements

We conducted a prospective study to determine the relationship between central (CVP) and peripheral (PVP) venous pressures in critically ill patients. CVP and PVP were measured on five different occasions in 20 critically ill patients in the intensive care unit. Results showed that the mean difference between PVP and CVP was 4.4 mmHg (95% CI= 3.7 to 5.0). However, PVP might be 1.9 mmHg below (95% CI=0.7 to 3.1) or 10.6 mmHg above (95% CI=9.4 to 11.8) the CVP. The mean difference between changes in PVP and corresponding changes in CVP was 0.3 mmHg (95%CI=-0.1 to 0.7). The actual change in PVP could be 3.0 mmHg below (95% CI=2.3 to 3.7) or 3.6 mmHg above (95% CI=2.9 to 4.3) the change in CVP. Overall, the direction of change in PVP (rise or drop) predicted a same direction of change in CVP with an accuracy of 78%. Changes in PVP ≥2 mmHg predicted a change in same direction of CVP with an accuracy of 90%. The direction of changes in CVP ≥2 mmHg were predicted by the direction of change in PVP with an accuracy of 91%. We conclude that PVP measurement does not give an accurate estimate of the absolute value of CVP in individual patients. However, as changes in PVP parallel, in direction, changes in CVP, serial measurements of PVP may have a value in determining volume status and guiding fluid therapy in critically ill patients.

Rapid radioisotopic procedure for determination of nortriptyline in plasma.

1976 ◽  
Vol 22 (6) ◽  
pp. 761-764 ◽  
Author(s):  
K P Maguire ◽  
G D Burrows ◽  
J P Coghlan ◽  
B A Scoggins
Keyword(s):  
Therapeutic Response ◽  
Antidepressant Drugs ◽  
Tricyclic Antidepressant ◽  
A Value ◽  
Drug Concentrations ◽  
The Mean ◽  
The Relationship ◽  
Mean Concentration ◽  
Double Isotope

Abstract With the widespread use of tricyclic antidepressant drugs, the relationship between the concentration of the drug in the plasma and the therapeutic response is of considerable interest. We describe a double-isotope derivative dilution procedure for measuring plasma nortriptyline. In the method, [14C]nortriptyline is used for estimating procedural losses and [3H]acetic anhydride for derivative formation. The assay is rapid and adequately specific, sensitive, precies, and reproducible for routine clinical use. We used it to investigate the variation in steady-state drug concentrations in plasma of persons who were on a 150 mg/day dose of nortriptyline. Intra-individual variation from day to day was 10-14%. This variation was not significantly affected by the dosage schedule, the time of sampling after an oral dose, or the storage of the plasma samples. For 19 patients on 150 mg of nortriptyline per day, the mean concentration in plasma was 181 +/- 22 (SE) mug/liter, a value that compares well with our previous findings and those of other groups.

Multi-Center Calibration of the Second Reference Material for Thromboplastin, Rabbit, Plain, Coded CRM 149R

1991 ◽  
Vol 65 (03) ◽  
pp. 263-267 ◽  
Author(s):  
A M H P van den Besselaar ◽  
R M Bertina
Keyword(s):  
Reference Material ◽  
Standard Error ◽  
Standard Errors ◽  
Sensitivity Index ◽  
Long Term Stability ◽  
Significant Bias ◽  
The Mean ◽  
The Relationship ◽  
International Sensitivity Index

SummaryIn a collaborative trial of eleven laboratories which was performed mainly within the framework of the European Community Bureau of Reference (BCR), a second reference material for thromboplastin, rabbit, plain, was calibrated against its predecessor RBT/79. This second reference material (coded CRM 149R) has a mean International Sensitivity Index (ISI) of 1.343 with a standard error of the mean of 0.035. The standard error of the ISI was determined by combination of the standard errors of the ISI of RBT/79 and the slope of the calibration line in this trial.The BCR reference material for thromboplastin, human, plain (coded BCT/099) was also included in this trial for assessment of the long-term stability of the relationship with RBT/79. The results indicated that this relationship has not changed over a period of 8 years. The interlaboratory variation of the slope of the relationship between CRM 149R and RBT/79 was significantly lower than the variation of the slope of the relationship between BCT/099 and RBT/79. In addition to the manual technique, a semi-automatic coagulometer according to Schnitger & Gross was used to determine prothrombin times with CRM 149R. The mean ISI of CRM 149R was not affected by replacement of the manual technique by this particular coagulometer.Two lyophilized plasmas were included in this trial. The mean slope of relationship between RBT/79 and CRM 149R based on the two lyophilized plasmas was the same as the corresponding slope based on fresh plasmas. Tlowever, the mean slope of relationship between RBT/79 and BCT/099 based on the two lyophilized plasmas was 4.9% higher than the mean slope based on fresh plasmas. Thus, the use of these lyophilized plasmas induced a small but significant bias in the slope of relationship between these thromboplastins of different species.

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