Papers by Keyword: MDF

Abstract: The main goal of this research work is to study and evaluate the muscles force and fatigue of Gastrocnemius Medialis (GMS), Gluteus Maximus (GM), and Gastrocnemius Lateralis (GL) during running for 400-meters based on surface Electromyography (sEMG) signals. The sEMG signals of the selected muscles from the right leg have been collected by using bipolar electrodes from 15 subjects during the run on the tartan athletic track with two pacing strategies. The first strategy: 1^st 200-meters running 87% - 94% of full speed and last 200-meters sprinting (full speed). The second strategy: 1^st 300-meters running 87% - 94% of sprinting and last 100-meters sprinting. The rate of fatigue has been calculated by using Root Mean Square (RMS) and Median Frequency (MDF) features. Then, the slopes of linear regression were calculated from both RMS and MDF at each 100-meters. The linear slope values represented the rate of fatigue and force. From the results of 1^st and 2^nd running strategies, the force of GM and GL muscles increased during the 4^th 100-meters of the 1^st strategy and decreased with GM and GMS muscles during the 4^th 100-meters of the 2^nd strategy. The less index fatigues were during the 1^st strategy for most selected muscles. Finally, it can be concluded the running with the 1^st strategy get less fatigues and the force of most selected muscles increased compared with the 2^nd strategy based on the results of time and frequency domain features (RMS and MDF).

Abstract: Heat treatment of wood is a promising alternative in improving its dimensional stability. The action of heat ensures the good quality of the treated wood product, with better performance in environments with high humidity. To prove the positive effect of this treatment, a test in which the specimens are weathered for a certain period of time termed as natural aging was performed. The aim of this study was to evaluate the effect of aging on heat-treated medium-density fiberboard (MDF) panels. Commercial MDF panels produced with pinewood adhesive and urea-formaldehyde were used. The experiment included seven test treatments [at 200, 225, and 250°C heat temperatures for 5 and 10 min] and a control treatment (without heat treatment). The products subjected to these treatments were weathered for 40 days, and climatological data were monitored daily. The results suggested that: 1) There is a decreasing trend in density with increasing time and temperature; 2) the treatment time and temperature had no effect on the ownership of the static bending for modulus of elasticity (MOE); 3) the time period is correlated with the treatment temperature for modulus of rupture (MOR) property; and 4) the thermal treatment of MDF panels did not allow the maintenance of the properties of MOR and MOE static bending strength after natural aging.

Abstract: This research presents a hybrid Genetic Algorithm Neural Network (GA-NN) model to replace the physical tests procedures of Medium Density Fiberboard (MDF). Data included in the model is MDF properties and its fiber characteristics. Multilayer Perceptron (MLP) NN model is reliable to learn from seven inputs fed to the network to produce prediction of three targets. In order to avoid result from local optimum scenario, GA optimizes synaptic weights of the network towards reducing prediction error. The research used a fixed probability rates for crossover and mutation for hybrid GA-NN model. GA-NN model is further improved using adaptive mechanism to help identify the best probability rates. The fitness value refers to Sum of Squared Error. Performance comparisons are among three models; namely NN with Back Propagation (BP), hybrid GA-NN and hybrid GA-NN with adaptive mechanism. Results show the hybrid GA-NN model perform much better than NN model used with back propagation optimizer. Adaptive mechanism in GA helps increase capability to converge at zero sooner than the ordinary GA.

Abstract: Structural analysis the shaft of defibrator and design a radial hydrostatic bearing experimental installation . employ the radial hydrostatic bearing which passed the exam in the radial hydrostatic bearing experimental installation will sharply reduce the time of recondition , Increase Efficiency of defibering ,reduce radial vibration of shaft , raising accuracy of defibering and improve the quality of the fibre

Abstract: Macro-defect-free (MDF) cements are cement-polymer composites and were developed by Birchall et al. three decades ago. The composites are produced by mixing small amounts of polymer and water with cement. However, they have a different production method than that of cement pastes, which was inspired by rubber production. Mixtures of cement, polymer and water are processed by using a two-roll mill. The composites are known with their high flexural strengths. Unfortunately, there are not any known commercial products using MDF cements because of their poor durability under moisture. In this study, MDF cements were prepared by using poly(vinyl alcohol--vinyl acetate) PVA, calcium aluminate cements and two different types of epoxy resins. Epoxy resins were a diglycidyl ether of bisphenol A and a mixture of a diglycidyl ethers of bisphenol A and F. Durability performance was compared with respect to biaxial flexural strengths, contact angle and atomic force microscopy (AFM) for the specimens stored in water.

Abstract: Texture evolution in the MDF processed ZK60 along forging axis was investigated by advanced neutron diffraction. Texture analysis was related to the deformation mechanism. Results showed that basal planes deformation was dominated and accommodated by non-basal and twinning. Gradient texture indicated an inhomogeneous distribution of imposed strains along forging direction. This could be related to the non-precise MDF processing.

Abstract: Thermagravimetric and combustion characteristics of binderless fiberboard (BF) were investigated. Fibers prepared by traditional heat grinding (FB) and which prepared in the presence of trivial inorganic acid during grinding (FBA) were used as compared. The results show that the total weight lost during thermal decomposition following as: BF > FBA > FB. The order of initial decomposition temperature was that FB > BF > FBA. Thermagravimetric weight loss rate in pyrolysis of woodfiber and binderless fiberboard got from adding minim inorganic acid in the heat grinding system to heat grinding were faster compared to the woodfiber made by heat grinding. Combustion characteristics results revealed that heat release rate and total heat release amount of BF were larger than that of FB. Smoking ratio of BF was larger than that of FB before the flaming combustion, but t less than that of FB after the flaming combustion. The concentration of produced CO2 and CO for BF during combustion was higher than FB.

Abstract: Grain boundary character in samples of Zr701 annealed at two different temperatures has been investigated in terms of lattice misorientation. The main difference between the two samples was the extent of grain growth post-recrystallization. The textures were typical for the material. Differences between the texture-based misorientation distribution function (T-MDF) and the microstructure-based MDF (M-MDF) revealed significant preferences for certain grain boundary types, notably those with <11-20> rotation axes.