scholarly journals Strength Properties of Structural Glulam Manufactured from Pine (Pinus sylvestris L.) Side Boards

Materials ◽  
2021 ◽  
Vol 14 (23) ◽  
pp. 7312
Author(s):  
Radosław Mirski ◽  
Dorota Dziurka ◽  
Marcin Kuliński ◽  
Adrian Trociński ◽  
Jakub Kawalerczyk ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Pinus Sylvestris ◽  
Bending Strength ◽  
Strength Properties ◽  
Structural Timber ◽  
The Difference

The aim of this study was to assess the static bending strength of pine glulam manufactured when obtaining the main yield, i.e., structural timber or timber to be used in the production of structural glulam. Analyses were conducted on pine timber harvested from three different locations in Poland. Two beam variants were manufactured, differing in the timber arrangement, horizontal vs. vertical. It was shown that the static bending strength of beams manufactured in the vertical timber arrangement variant is slightly higher than that of beams produced from horizontally arranged layers, with the latter beams characterised by a smaller confidence interval for this strength. Moreover, it was found that the difference in the value of the 5th percentile for both beam types is slight and both beam types are considered to exhibit a high bending strength of over 40 N/mm2.

scholarly journals Strength Properties of Structural Glulam Elements from Pine (Pinus sylvestris L.) Timber Reinforced in the Tensile Zone with Steel and Basalt Rods

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2574
Author(s):  
Radosław Mirski ◽  
Marcin Kuliński ◽  
Dorota Dziurka ◽  
Marta Thomas ◽  
Ryszard Antonowicz
Keyword(s):  
Pinus Sylvestris ◽  
Modulus Of Elasticity ◽  
Bending Strength ◽  
Strength Properties ◽  
Lower Strength ◽  
Industrial Practice ◽  
Potential Applicability ◽  
Tensile Zone

The study analyzed potential applicability for asymmetric reinforcement of glulam beams using materials with a higher modulus of elasticity. Reinforcement elements included smooth and ribbed steel rods as well as basalt rods. These rods were placed only in the tensile zone, assuming that they will not only impart increased rigidity but first of all will reduce the scatter of bending strength values. What is significant, tests were conducted on timber with defects, as it is most commonly used in industrial practice. Analyses showed that this provides an increase in rigidity close to the assumed level. A significant increase in strength was observed. The manufactured beams reinforced with steel and basalt rods were characterized by mean bending strength amounting to 54 and 47 N/mm2, respectively. However, no significant improvement was found in the scatter of the observed variable. Beams reinforced with steel exhibit a 20% higher strength than unreinforced beams. The lower strength of beams reinforced with basalt bars may be related to the lower modulus of elasticity of the basalt itself.

scholarly journals Influence of the Structure of Lattice Beams on Their Strength Properties

Materials ◽  
2021 ◽  
Vol 14 (19) ◽  
pp. 5765
Author(s):  
Radosław Mirski ◽  
Łukasz Matwiej ◽  
Dorota Dziurka ◽  
Monika Chuda-Kowalska ◽  
Maciej Marecki ◽  
...  
Keyword(s):  
Manufacturing Process ◽  
Bending Strength ◽  
Strength Properties ◽  
Metal Plate ◽  
Structural Timber ◽  
The Other ◽  
Load Bearing ◽  
Other Hand ◽  
The One ◽  
Current Stage

This paper presents the strength properties of wooden trusses. The proposed solutions may constitute an alternative to currently produced trusses, in cases when posts and cross braces are joined with flanges using punched metal plate fasteners. Glued carpentry joints, although requiring a more complicated manufacturing process, on the one hand promote a more rational utilisation of available structural timber resources, while on the other hand they restrict the use of metal fasteners. The results of the conducted analyses show that the proposed solutions at the current stage of research are characterised by an approx. 30% lower static bending strength compared to trusses manufactured using punched metal plate fasteners. However, these solutions make it possible to produce trusses with load-bearing capacities comparable to that of structural timber of grade C24 and stiffness slightly higher than that of lattice beams manufactured using punched metal plate fasteners. The strength of wooden trusses manufactured in the laboratory ranged from nearly 20 N/mm2 to over 32 N/mm2. Thus, satisfactory primary values for further work were obtained.

scholarly journals Density, hardness and strength properties of densified fir and aspen woods pretreated with water repellents

Holzforschung ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Hüseyin Pelit ◽  
Fatih Emiroglu
Keyword(s):  
Compression Ratio ◽  
Bending Strength ◽  
Linseed Oil ◽  
Vacuum Treatment ◽  
Strength Properties ◽  
Aspen Wood ◽  
Positive Effect ◽  
Water Repellents ◽  
Impregnated Wood ◽  
Compression Temperature

AbstractIn this study, the effect of thermo-mechanical densification on the density, hardness, compression strength, bending strength (MOR), and modulus of elasticity (MOE) of fir and aspen wood pretreated with water repellents was analyzed. Wood specimens were impregnated with paraffin, linseed oil and styrene after pre-vacuum treatment. Then, the impregnated wood specimens were densified with compression ratios of 20 and 40%, and at 120, 150 and 180 °C. The results indicated that the density, hardness and strength properties of the all densified specimens (untreated and impregnated) increased depending on the compression ratio and temperature. For all tested properties, higher increases were obtained in the paraffin and styrene pretreated specimens compared to untreated samples. However, the increase rates in linseed oil pretreated specimens were generally lower than untreated specimens. Regarding water repellents the most successful results in all tested properties were determined in styrene pretreated specimens. The density, hardness and strength properties of all specimens increased with the increase in compression ratio. On the other hand, the increase in the compression temperature negatively affects the properties of untreated and linseed oil pretreated specimens, while having a generally positive effect on the properties of paraffin pretreated specimens. However, all tested properties of styrene pretreated specimens have increased significantly due to the increase in compression temperature. The increasing strength properties of wood as a result of densification have increased much more with paraffin and especially styrene pretreatment. These combinations can be considered as an important potential for applications that require more hardness and strength.

scholarly journals Significant Associations of lncRNA H19 Genotypes with Susceptibility to Childhood Leukemia in Taiwan

2021 ◽  
Vol 14 (3) ◽  
pp. 235
Author(s):  
Jen-Sheng Pei ◽  
Chao-Chun Chen ◽  
Wen-Shin Chang ◽  
Yun-Chi Wang ◽  
Jaw-Chyun Chen ◽  
...  
Keyword(s):  
Confidence Interval ◽  
Childhood Leukemia ◽  
Healthy Controls ◽  
Nucleotide Polymorphisms ◽  
Wild Type ◽  
Single Nucleotide ◽  
Genotypic Distribution ◽  
Heterozygous Variant ◽  
Significant Difference ◽  
The Difference

The purpose of our study was to investigate whether genetic variations in lncRNA H19 were associated with susceptibility to childhood leukemia. Two hundred and sixty-six childhood leukemia patients and 266 healthy controls were enrolled in Taiwan, and two single nucleotide polymorphisms (SNPs), rs2839698 and rs217727, in H19 were genotyped and analyzed. There was a significant difference in the genotypic distribution of rs2839698 between patients and healthy controls (p = 0.0277). Compared to the wild-type CC genotype, the heterozygous variant CT and homozygous variant TT genotypes were associated with significantly increased risks of childhood leukemia with an adjusted odd ratio (OR) of 1.46 (95% confidence interval (CI), 1.08–2.14, p = 0.0429) and 1.94 (95%CI, 1.15–3.31, p = 0.0169), respectively (pfor tread = 0.0277). The difference in allelic frequencies between childhood leukemia patients and controls was also significant (T versus C, adjusted OR = 1.53, 95%CI, 1.13–1.79, p = 0.0077). There were no significant differences in the genotypic and allelic distributions of rs217727 between cases and controls. Interestingly, the average level of H19 rs2839698 was statistically significantly higher for patients with CT and TT genotypes than from those with the CC genotype (p < 0.0001). Our results indicate that H19 SNP rs2839698, but not rs217727, may serve as a novel susceptibility marker for childhood leukemia.

Study on Particleboard made from Nipa palm (Nypa fruticans) stem wood and Rajkoroi (Albizia richardiana) wood

2018 ◽  
Vol 25 (1) ◽  
pp. 15-18
Author(s):  
Md. Mahabubur Rahaman ◽  
◽  
Khurshid Akhter ◽  
S. Hossain ◽  
Md. Rakibul Islam ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Dimensional Stability ◽  
Bending Strength ◽  
Strength Properties ◽  
Wood Chips ◽  
Standard Specification ◽  
Stem Wood ◽  
Nypa Fruticans ◽  
Albizia Richardiana ◽  
Nipa Palm

The study was conducted to find out the suitability of making particleboard using nipa palm (Nypa fruticans) stem wood and rajkoroi (Albizia richardiana) wood chips. Particleboards were fabricated at six different ratios of nipa palm stem and rajkoroi wood chips such as 100:0, 75:25, 50:50, 25:75, 10:90 and 0:100. Characteristics of particleboards such as modulus of rupture, internal bond strength, water absorption, thickness swelling and moisture content were measured. Results shows that particleboards made from 100% rajkoroi wood chips have the highest static bending properties and highest tensile strength properties of other particleboards but 100% nipa palm stem wood chips have the lowest static bending and lowest tensile strength properties of other particleboards. 10% nipa palm stem wood chips particleboard have the highest bending strength and tensile strength is better than 100% nipa palm stem wood chips and other mixing chips of particleboards. Mechanical, water resistance and dimensional stability properties were tested according to Indian standard specification. Tensile strength passed the British and German standard specification and nearest to Bureau of Indian Standard, bending strength was found nearest to Indian Standard but lower than German and British Standard specification. Strength property of rajkoroi wood chips particleboard is higher than nipa palm steam wood chips particleboard but dimensional stability is lower than nipa palm steam wood chips particleboard.

scholarly journals Measuring the effectiveness of online problem solving for improving academic performance in a probability course

2022 ◽  
Author(s):  
José Antonio González ◽  
Mónica Giuliano ◽  
Silvia N. Pérez
Keyword(s):  
Problem Solving ◽  
Confidence Interval ◽  
Student Performance ◽  
Online Homework ◽  
Methodological Issues ◽  
Engineering Programs ◽  
Technological Diversity ◽  
The Subject ◽  
The Difference ◽  
Written Test

AbstractResearch on impact in student achievement of online homework systems compared to traditional methods is ambivalent. Methodological issues in the study design, besides of technological diversity, can account for this uncertainty. Hypothesis This study aims to estimate the effect size of homework practice with exercises automatically provided by the ‘e-status’ platform, in students from five Engineering programs. Instead of comparing students using the platform with others not using it, we distributed the subject topics into two blocks, and created nine probability problems for each block. After that, the students were randomly assigned to one block and could solve the related exercises through e-status. Teachers and evaluators were masked to the assignation. Five weeks after the assignment, all students answered a written test with questions regarding all topics. The study outcome was the difference between both blocks’ scores obtained from the test. The two groups comprised 163 and 166 students. Of these, 103 and 107 respectively attended the test, while the remainder were imputed with 0. Those assigned to the first block obtained an average outcome of −1.85, while the average in the second block was −3.29 (95% confidence interval of difference, −2.46 to −0.43). During the period in which they had access to the platform before the test, the average total time spent solving problems was less than three hours. Our findings provide evidence that a small amount of active online work can positively impact on student performance.

scholarly journals Potential of seasonal hydrological forecasting of monthly run-off volumes for the Rhone and Arve Rivers from April to July

2018 ◽  
Author(s):  
Oriane Etter ◽  
Frédéric Jordan ◽  
Anton J. Schleiss
Keyword(s):  
Confidence Interval ◽  
Seasonal Forecast ◽  
Seasonal Forecasting ◽  
Average Error ◽  
Lead Times ◽  
Streamflow Forecasting ◽  
Rhône River ◽  
Run Off ◽  
Rhone River ◽  
The Difference

Abstract. In a context where water management is becoming increasingly important, reliable seasonal forecasting of discharge in rivers is crucial for making decisions several months in advance. This paper explores the potential of seasonal forecasting of run-off volumes produced by ensemble streamflow forecasting using past climatology and comparing it to the more commonly used average of past discharge measurements. The seasonal forecast was obtained for the Arve and Rhone rivers by simulation using the Routing System model for lead times of 30, 90 and 120 days. The initialization was performed on a validated simulation of 12 and 16 years for the Arve and Rhone rivers, respectively, obtained through long-term calibration. The performance was assessed by indicators called accuracy and thinness. The normalized mean average error (NMAE) was used to compare the performance of the seasonal forecast with the average of the past measurements. After a bias correction of the seasonal forecast of the Rhone River with the observed run-off volumes during the different lead times, the correlation of the median forecast with the measurements (accuracy) was larger than 0.55 for all lead times from April to July. The Arve River's accuracy was improved by disregarding the year 2007 member, leading to the floods of the 3rd and 9th of July, for lead times of 90 and 120 days. This resulting in the period of April to July having correlation accuracies higher than 0.5. For both rivers, the 80 % confidence interval of the seasonal forecast was relatively thin compared to the measurements (thinness) for the months of April to July. The NMAE was used to validate the range of validity of the forecast. The correction of the forecast resulted in more months being favorable for seasonal forecasting for the Rhone River. The post-processing on the Arve River decreased the difference between the measurement and the forecast (NMAE). Further investigation should concentrate on dividing the meteorological datasets to produce a strong median forecast and confidence interval

scholarly journals استراتيجية تعليم المفردات بالغناء في البرنامج المكشف لتعليم اللغة العربية بجامعة مولانا مالك إبراهيم الإسلامية الحكومية مالانج

2018 ◽  
Vol 1 (1) ◽  
pp. 1-24
Author(s):  
ABDUL BASID
Keyword(s):  
Experimental Study ◽  
Confidence Interval ◽  
Teaching Strategy ◽  
T Test ◽  
Learner Participation ◽  
Instructional Activities ◽  
Class B ◽  
Research Problems ◽  
The Difference

Abstrak Penelitian ini dilakukan untuk mengetahui strategi pengajaran kosakata dengan menggunakan (strategi bernyanyi). Rumusan masalah penelitian ini adalah (1) bagaimana proses strategi pengajaran kosakata bahasa Arab dengan menggunakan strategi bernyanyi, (2) bagaimana efektivitas penggunanan strategi pengajaran kosakata bahasa Arab dengan menggunakan strategi bernyanyi. Desain Penelitian yang digunakan adalah studi eksperimental.  Populasi dalam peneltian ini adalah seluruh mahasiswa progam Studi PBA di UIN Maulana Malik Ibrahim, adapun sampel yang diambil dari populasi tersebut adalah mahasiswa Program Studi PBA kelas B-4 UIN Maulana Malik Ibrahim Malang. Hasil dari penelitian ini menunjukkan bahwa (1) proses strategi pengajaran kosakata bahasa Arab dengan strategi bernyanyi yaitu aktivitas pra instruksional, petunjuk isi dan pembelajaran. Partisipasi peserta didik, penilaian, aktifitas timbal balik (2) efektifitas strategi pengajaran bahasa Arab dengan menggunakan strtegi bernyanyi menunjukkan nilai t-test lebih kecil daripadda t-tabel 0,243< 2, 0639, nilai t-test 0,243 itu berada diantara nilai interval konfidensi perbedaan, yaitu nilai tertinggi 1,901 dan nilai terendah 1,501 serta nilai signifikansi 0,810 yang mania lebih kecil dari t-table yaitu 2,0639     Abstract             This reserach elaborates on the teaching strategy of Arabic vocabulary by using the song. The research problems are: (1) what is the process of the teaching strategy of Arabic vocabulary by using the song; and (2) what is the effectiveness of the teaching strategy of Arabic vocabulary by using the song. The design of this study is experimental study. The population of this research is all students in PPBA UIN Maulana Malik Ibrahim Malang and the sample of this research is all students in class B-4 PPBA UIN Maulana Malik Ibrahim Malang. The result of this study is: (1) the process of the teaching strategy of Arabic vocabulary by using the song consist of several stages. They are pre instructional activities, content and learning guidance, learner participation, assessment, and follow-through activities; (2) the effectiveness of the teaching strategy of Arabic vocabulary by using the song is the value of t-test is smaller than t-table 0,243 < 2,0639, the value t-test 0,243 is between the value of confidence interval of the difference, upper 1,901 and lower -1,501, and signified value is 0,810 < t-table is 2,0639.     ملخص ويوضح هذا البحث التركيز في استراتيجية التدريس للمفردات العربية باستخدام الأغنية. وأما مشكلة البحث فهي: أولا، ما هي عملية إستراتيجية التدريس للمفردات العربية باستخدام الأغنية؛ وثانيا؛ ما هي فعالية استراتيجية التدريس للمفردات العربية باستخدام الأغنية. ويكون تصميم هذه الدراسة من نوع الدراسة التجريبية. أما مجتمع البحث لهذا البحث هو جميع الطلاب في قسم تعليم اللغة العربية بجامعة مولانا مالك إبراهيم الإسامية الحكمومية مالانج، والعينة من هذا البحث هو جميع الطلاب في الصف B-4 قسم تعليم اللغة العربية بجامعة مولانا مالك إبراهيم مالانج. والنتائج من هذه الدراسة هي: (1) عملية إستراتيجية التدريس للمفردات العربية باستخدام الأغنية تتكون من عدة مراحل. وهي أنشطة تعليمية سابقة، ومحتوى وإرشادات تعليمية، ومشاركة للمتعلم، وتقييم، وأنشطة متابعة. (2) أما فاعلية إستراتيجية التدريس للمفردات العربية باستخدام الأغنية هي قيمة اختبار t أصغر من t-تابل 0،243 <2،0639، قيمة t-تيست 0،243 بين قيمة فاصل الثقة في الفرق، العلوي 1،901 وأقل -1،501، وقيمة معترف بها هو 0،810 <t- الجدول هو 2،0639.  

scholarly journals Selected physical and mechanical properties of Scots pine (Pinus sylvestris L.) wood from stands of younger age classes as criteria for rational utilization of timber

2021 ◽  
Vol 27 (1) ◽  
Author(s):  
Przemysław Marcin Pikiński ◽  
Jaroslav Szaban ◽  
Gerda Šilingienė ◽  
Robert Korzeniewicz ◽  
Witold Pazdrowski
Keyword(s):  
Mechanical Properties ◽  
Pinus Sylvestris ◽  
Scots Pine ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Growth Conditions ◽  
Tree Age ◽  
Coniferous Forests ◽  
Forest Site ◽  
Quality Coefficient

The aim of this study was to assess the quality of Scots pine (Pinus sylvestris L.) wood depending on the age of trees, forest site conditions and social class of tree position in the stand. Analyses were based on the determination of specific density and static bending strength, as well as the strength quality coefficient. It was to determine changes in physical and mechanical properties of timber depending on tree age as well as growth conditions reflected in the forest site such as fresh mixed coniferous forests and fresh mixed broadleaved forests. Experimental plots were established in 6 localities with 30, 40 and 60-year-old trees. In each of the stands, a 1-hectare experimental plot was established. Based on the measured DBH and tree height, dimensions of three mean sample trees were calculated, while the classification of social class of tree position in the stand developed by Kraft (1884) was also applied. Analyses were conducted on wood samples with 12% moisture content. Strength tests on wood samples were performed on an Instron 33RH204 universal strength testing machine. A detailed analysis showed properties of pine wood are improved with an increase of tree age in both forest sites. Statistically significant differences were observed for wood density and static bending strength. More advantageous properties were observed for wood of pines from the less fertile forest site, i.e., fresh mixed coniferous forests. Density and static bending strength were markedly determined by tree age and growth conditions. The static bending strength quality coefficient from pines growing in the fresh mixed coniferous forests increased between 30 and 40 years, similarly as it was for the fresh mixed broadleaved forests, while between 40 and 60 years, it deteriorated for the fresh mixed coniferous forests. Wood density from the fresh mixed coniferous forests was by 3% to 7% greater than pines growing in fresh mixed broadleaved forests. In turn, static bending strength of wood from pines growing in fresh mixed coniferous forests was by 4% to 10% greater than trees from the fresh mixed broadleaved forests.  Keywords: Scots pine, wood properties, forest site, Poland

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