Bahram Mardani; Ahmad Jahan latibari; Ajang Tajdini
Abstract
Natural disasters and the need to facilitate and relief the consequences of such disasters has initiated global crisis in its respective management. Reducing the variabilities of inhabitants requires the integrated system to battle against such devastations and crises. This research presents the application ...
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Natural disasters and the need to facilitate and relief the consequences of such disasters has initiated global crisis in its respective management. Reducing the variabilities of inhabitants requires the integrated system to battle against such devastations and crises. This research presents the application of Delfi method to identify the influential factors on risk management model risk management model for the wooden structures in Iran. The statistical population of the study consisted of the academic and organizational experts. A total of 30 individuals were interviewed using a purposive non-random sampling technique as well as data adequacy and saturation principle. A semi-structured interview was used to collect the required data. Delfi method was applied for data analysis in qualitative section. The results indicated that 43 risk factors are influential in wooden structures which can be classified as internal and external risks. Among these risk factors, 11 are considered as the major factors which influences the application of risk management in construction of wood structures in earthquake prone regions of Iran.
Pulp and paper
Seyyed Abbas Mehdikhah; Shademan Pourmousa; Aghang Tajdini
Abstract
Wet tensile strength is very important in some cellulosic health products. When these products produced during the recycling process some of the characteristics in pulp suspension due to lack of stability of desirable quality properties is difficult to achieve. In this study, using a variety of different ...
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Wet tensile strength is very important in some cellulosic health products. When these products produced during the recycling process some of the characteristics in pulp suspension due to lack of stability of desirable quality properties is difficult to achieve. In this study, using a variety of different doses of cationic polymers with laboratory methods, at first reduced the anionic charge amount in pulp suspension gradually. Then the Poly (amine) amide epichlorohydrin and its stabilizer injected to the suspension. The pulp suspension and physical properties of handsheets were evaluated. The type and amount of cationic polymers have a significant effect on the reduction of anionic charge of pulp suspension and the resulting increase in wet tensile strength and other physical resistance of handsheets. The effect of polymers resulted that anionic charge of suspension improved from 237 µeq /L in control samples to32µeq/L in the best conditions. Physical properties of handsheets improved after chemical treatments with different amounts of variety of polymers. Wet tensile strength increased than13 N/m to 121N/m, dry tensile strength improved 2730 N/m to 2860 N/m the burst resistance increased than 146 KPa to 160KPa in superior treatment using 135 mg/L of Gfloc F10. Stepwise regression analysis showed the significant relationship of the anionic charge in the pulp suspension and the physical properties of handsheets. So using different cationic polymers can be reduced the anionic charge of the pulp suspension and improved the quality properties of paper base products.
Mechanical conversion of wood and wooden fittings
Soheila Zamaninasab; amir lashgari; azhang tajdini
Abstract
In this research, resistance and stress concentration on the seat structure were examined by changing the type of connection (tongue and groove connection , and double connection). platanus orientalis used to make wooden chairs. Moreover, we applied Ansys to calculate resistance and mechanical testing ...
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In this research, resistance and stress concentration on the seat structure were examined by changing the type of connection (tongue and groove connection , and double connection). platanus orientalis used to make wooden chairs. Moreover, we applied Ansys to calculate resistance and mechanical testing machine with a load of chairs 7/12 mm per minute to show the stress distribution on the chairs members . The results show that chairs by tongue and groove connection and having a simple structure and with bail , have more resistance and less stress distribution than a double chair with a simple structure and with indicating connection and the impact of the type of connection were significant on the chair resistance . The stress distribution shows that the maximum stress concentrations on the horizontal joints are visible . Finite element models show that the stress distribution is more uniform in chairs with tongue and groove connections.
Management and Economics wood
Amir Tavakkoli; Amir Hooman Hemmasi; Mohammad Talaeipour; Behzad Bazyar; Ajang Tajdini
Abstract
The objective of the research is to forecast the trend of the printing and writing paper consumption in Iran for a five-year period using both modern and classical methods. In order to do the forecasting, predictability of time series was primarily studied using Durbin-Watson and Runs tests. Then, artificial ...
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The objective of the research is to forecast the trend of the printing and writing paper consumption in Iran for a five-year period using both modern and classical methods. In order to do the forecasting, predictability of time series was primarily studied using Durbin-Watson and Runs tests. Then, artificial neural network model (multilayer perceptrons (MLP)) and univariate and multivariate classical forecasting models such as univariate single exponential smoothing (SES), double exponential smoothing (DES), holt-winters exponential smoothing (HWES) and Box- Jenkins (ARIMA) models, and multivariate econometric model all together were compared in terms of the standard statistical measures. Finally, the consumption of printing and writing paper in Iran was forecasted up to the year 2017 using the most appropriate model. The results of both the parametric test of Durbin-Watson and non-parametric test of Runs show that, the printing and writing consumption series is non-random and predictable. The results of comparing different forecast methods showed that the artificial neural network model has higher forecasting accuracy than the classical models and it is more appropriate for the five-year forecast period. Also, the results of forecasting by using neural network model (MLP), revealed that the printing and writing paper consumption in Iran is forecasted to increase by 5.3%, from around 375 thousand tons in 2012 to 420 thousand tons in 2013, but it falls over the five-year forecast period, from 5.3% in 2013 to 0.07% in 2017.
Physics and Mechanical Wood
Ardlan Doreemam; Vahidreza Safdari; Abolfazl Kargarfard; Ajang Tajdini
Abstract
In this study, the effect of using waste of Alnus subcordata and Poplar wood in manufacturing particle board was investigated. The particle boards were produced by adding (0-25-50-75-100)% alder branches with poplar wood and two press temperatures 170°C and 180 °C. In total, 30 particleboards ...
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In this study, the effect of using waste of Alnus subcordata and Poplar wood in manufacturing particle board was investigated. The particle boards were produced by adding (0-25-50-75-100)% alder branches with poplar wood and two press temperatures 170°C and 180 °C. In total, 30 particleboards (10 treatments with 3 replications) were made and data was analyzed with complete randomized design. Results showed that particleboards which were made of 75% alder branches and 25% poplar wood with press temperature of 180 °C had the most flexural strength. In addition, this study manifests that the increase of alder branches up to 25% led to the enhancement of modulus of elasticity of particle boards while adding more than 25% caused in the decrease of the modulus of elasticity. The increase of alder branches would augment the internal bounding and thickness swelling of particleboards. Therefore, the particleboards of 100% alder branches had the best internal bonding. However, this research concluded that the press temperature would not any significant effects on mechanical and physical characteristics.
Amir Zamani; Ahmad Jahan Latibari; Aghang Tajdini; Abolfazl Kargarfard
Abstract
In this investigation, the surface chemical properties of the beech wood layers were characterized and the impact of drying condition on the strength of the bond was examined. Defect free beech logs were harvested and then the layers were prepared. The moisture content of the specimens were adjusted ...
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In this investigation, the surface chemical properties of the beech wood layers were characterized and the impact of drying condition on the strength of the bond was examined. Defect free beech logs were harvested and then the layers were prepared. The moisture content of the specimens were adjusted at 30, 40 and 50% (dry basis) and then the specimens were air dried under the environment of 30% relative humidity and 21ºC to reach the equilibrium moisture content of about 10% (dry basis). The pH and buffering capacity of the surface layer and the layer 0.5 mm underneath the surface were measured. The dried specimens were bonded using urea-formaldehyde resin and the tensile strength and wood failure were measured using relevant ASTM method. The results showed that as the moisture content prior to air drying was increased, the tensile strength was reduced, but the effect of this variable on tensile strength was not statistically significant. However, the effect of moisture content on wood failure was statistically significant at 99% significance level. The effect of the pH of the under layer on both tensile strength and wood failure was statistically significant at 95%. As the moisture content of the wood increased, the pH of the surface layer increased and the strength of the bond with urea-formaldehyde resin was deteriorated. At higher initial moisture of the wood, the alkaline buffering capacity of the surface layer was lower and its effect of the strength was not statistically significant, but it was significant on wood failure at 99% level. The alkaline buffering capacity of under layer was also changed and statistically affected the bond strength and wood failure at 95% level. The higher alkaline buffering capacity of the under layer adversely affected the tensile strength of the bond. The lowest acid buffering capacity was measured from specimens with 40% initial moisture content and as the acid buffering capacity was increased, the tensile strength was reduced and the wood failure was higher. The impact of surface layer acid buffering capacity on tensile strength was on statistically significant, but on wood failure was statistically significant at 99% level.
Porya Rezaei niaraki; Ahmad Jahan Latibari; Azhang Tajadini; Mehran Roohnia
Abstract
The influence of fiber lignin content and the dosage of coupling agent on the strength and physical properties of cellulosic fiber-polypropylene composite were investigated. The old corrugated container (OCC) fibers were delignified using sodium hydroxide to reach the lignin content of 2.7, 3.78, 5.26 ...
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The influence of fiber lignin content and the dosage of coupling agent on the strength and physical properties of cellulosic fiber-polypropylene composite were investigated. The old corrugated container (OCC) fibers were delignified using sodium hydroxide to reach the lignin content of 2.7, 3.78, 5.26 and 7%. Fibers were compounded with polypropylene by extrusion process using 20% fibers and 77% PP and the extrudate was cooled and grinded to fine granulates before injection molding. MAPP coupling agent was applied at three different levels (1, 2 and 3 percent based on the total weight of the composite). The strength properties of the composites were measured using relevant ASTM test methods and the results were statistically analyzed using factorial experiment under complete randomized design. The impact of fiber lignin content of flexural strength of composite was statistically significant at 98 percent significance level and the lowest and highest values of flexural strength of composite were measured at 3.78 percent and 7 percent lignin content of fiber. The interactive effect of fiber lignin and MAPP on the tensile strength and flexural modulus of elasticity of the composite showed that at lower values of lignin and higher dosage of MAPP, these properties are 38.7 and 3438 MPa respectively. Other strength values of the composites were also improved and at lower content of lignin and increaing dosages of the MAPP, the impact strength of the composites was increased from 52.82 J/m to 60.26 J/m.
Management and Economics wood
seyed amirabbas namaki
Abstract
Abstract In this paper, we attempted to investigate the relationship between consumption, demand for imports of fine paper and economic growth using annual time series data in the period of 1984 to 2010. Since the time series are non-stationary (Unit root) and can lead to spurious regression, the stationary ...
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Abstract In this paper, we attempted to investigate the relationship between consumption, demand for imports of fine paper and economic growth using annual time series data in the period of 1984 to 2010. Since the time series are non-stationary (Unit root) and can lead to spurious regression, the stationary of the variables are investigated in its logarithmic form using Augmented Dickey Fuller test (ADF) in two type of intercept without trend and intercept with trend. After applying the unit root test, in order to understand the interaction between economic growth and consumption and imports of fine papers and direction the causal relation, the vector auto regressive (VAR) approach including two models and the causality test of granger are used.The results indicate that GDP growth will increase the consumption of writing and printing papers but this relation is one-sided. On the other hand, there is no causality between changes in GDP and imports of printing and writing paper, and vice versa. Also, there is the one-side causality between GDP and consumption of newsprint. In the case ofThe Granger causality between economic growth and imports of newsprint, due to reject the null hypothesis, there was no relationship found, and vice versa
Amir Bagheri; Vahid reza Safdari; Amir Lashgari; Azhang Tajadini
Abstract
Ephedra shrubs are among native species of Iran and Turan habitat but their anatomical and physical characteristics have not been studied yet. In this study,physical characteristics of wood logs from three ephedra species including Mianeh Ephedra (Ephedra intermedia ),Goats Beard Ephedra (Ephedra ...
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Ephedra shrubs are among native species of Iran and Turan habitat but their anatomical and physical characteristics have not been studied yet. In this study,physical characteristics of wood logs from three ephedra species including Mianeh Ephedra (Ephedra intermedia ),Goats Beard Ephedra (Ephedra major) and Deserts Ephedra or Central Asian Ephedra (Ephedra strobilaceae Bge.) from desert areas of Yazd province were studied. Results shows that Iranian ephedra species similar to the others species show three key anatomical structures: Vessles, Theracheids and, Fibers. The presence of big pits simillar to tracheid pits in some vessel elements support the idea that they are a bridge group linking angiosperms and gymnosperms. Important anatomical features of Iranian ephedras include occurrence of clear and dendroied bodies, elongated and very hetrogenous wooden rayes and latticed vascular valves. Anatomical differences between the three ephedra species provide the key to identify them. There was not any significant difference between average physical characteristics (wet and dry density, shirinkage and swelling).Whereas, average shirinkage and swelling in radial direction was significantly higher than those in tangentiels direction.
Amir Mollahassani; Azhang Tajdini; Mehran Roohnia; Amir Tavakkoli
Abstract
The demand for the import of lumber as one of the most important imported sawnwood inIranduring the period of 1984 to 2009 is empirically analyzed using anOrdinary Least Squaremodel (OLS). Prior to estimation, Augmented Dickey Fuller (ADF) and Philips-Perron tests were applied to investigate the stationary ...
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The demand for the import of lumber as one of the most important imported sawnwood inIranduring the period of 1984 to 2009 is empirically analyzed using anOrdinary Least Squaremodel (OLS). Prior to estimation, Augmented Dickey Fuller (ADF) and Philips-Perron tests were applied to investigate the stationary character of the data. Also, to test the presence of Serial Autocorrelation in the error of the regression model Breusch-Godfrey test is used. The presence of a long-run relationship between demand for lumber import and the factors effective on it was measured by Engle –Granger and Johansen- Julius Cointegration tests and finally the causal relation in short-run was analyzed by the causality test of Granger. The results indicated that the nominal exchange rate and domestic production quantity variables imparts adverse impact and GDP and the export petroleum income impose positive impact on demand for import of lumber. Also, the results showed that there exist a long –run equilibrium relationship between lumber imports inIranand the selected macroeconomic and market variables. We find that there is a one-side causal relation from the mentioned explanatory variables to the dependence variable.
Vahid reza ُSafdari; Nima Eskini; Aghang Tajedini; Valima Bayramzadeh
Abstract
Abstract: Wood anatomy in addition to genetic is affected by environmental factors. One of the environmental factors is soil erosion which affects anatomical properties of roots considerably. Juniperus excelsa is one of Iranin indigenous softwood and has longevity and anatomical properties of its root ...
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Abstract: Wood anatomy in addition to genetic is affected by environmental factors. One of the environmental factors is soil erosion which affects anatomical properties of roots considerably. Juniperus excelsa is one of Iranin indigenous softwood and has longevity and anatomical properties of its root in two conditions: inside of soil and exposed one can reveal effects of soil erosion on wood anatomical properties of root. So many roots and barks of trees in inside of soils and exposed have been sampled and many micro-sections prepared by microtome and anatomical properties were investigated. Results showed that wood roots under soil conform of one row of late-wood and by exposing the lumen area of tracheids in early-wood and late-wood were decreased and the cells appear thicker and late-wood portion increased. The axial parenchyma inclusion of dark resins in exposed roots observed frequently. Meanwhile by exposing of roots the thickness of bark decreased and the thickness of phloem and periderm in exposed root is not as wide as normal roots.
Roholah Mohebi; Aghang Tajedini; Ahmad Jahan-Latibari; Amir Nourbakhsh
Abstract
The influence of different contents (0, 5 and 10% W/W)of silica and poplar wood powder ( 30 ,40 and 50% W/W of total weight of composite) on strength properties of Polypropylene/Wood powder/Silica composite was evaluated. Various components of composite was melt mixed using two screw counter retating ...
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The influence of different contents (0, 5 and 10% W/W)of silica and poplar wood powder ( 30 ,40 and 50% W/W of total weight of composite) on strength properties of Polypropylene/Wood powder/Silica composite was evaluated. Various components of composite was melt mixed using two screw counter retating extruder, followed by cooling and granulizing. Composite granules were injected into test samples. The results of strength properties measurements revealed that almost all strength values were improved. At higher content of silica, The MOR increased from 47.9 to 53.3 MPa, MOE from 2625 to 4517 MPa and MOE in tensile increased from initial value of 4525MPa (without silica) to 6884MPa (10% silica in composite). Marginal increase in tensile strength and Izod Impact strength was observed, but the hardness of the composite was improved from 66 to73.77 shoreD. At higher silica content, the density of the composite was higher, as expected.
