mokhtari

In the present study, the finite element method based on the shear-lag model was used for stress analysis as well as deformation of the creep stable state of short fiber composites under axial loading. A perfect fiber/matrix interface is assumed and the steady-state creep behavior of the matrix is described by Norton numerical model. Special boundary conditions applied to the unit cell model and imaginary fiber technique has been used. Then ANSYS software is used for the calculation of all stresses and strains at the fiber/matrix interface and the outer surface of the unit cell. Then the results were verified and the values of axial and shear stresses at different points of the composite were investigated. The results show that the composite unit cell can be used as a composite representative for stress analysis. Also, the use of an imaginary fiber technique is a useful and reliable way to achieve a stress transfer model. This Model has sufficient accuracy and contrary to previous studies can predict all stresses and strains in all points.

Turkish proverb dictionaries published in Turkish speaking regions of Iran are evaluated to explore to the extent they meet the criteria of reference works.

The list of books in the subject published in Iran was prepared by searching in the online catalog of the National Library of Iran. Thirty-four titles were identified an examined carefully using a researcher-made checklist based on the criteria proposed in the LIS literature for reference works.

Overall, the titles examined failed to meet the criteria. Problems include the lack of user guides, lack of cross-references, lack of detailed endbook indexes, and lack of unstructured entry contents. 

Preparing a handbook for future authors and greater involments of the academics in preparing such works are proposed.

In the recent decades, the increase in population, decrease in physical activities and consumption of improper food to fulfill the nutritional need have caused various diseases namely diabetes. The extract from the leaves of Stevia Rebaudiana plant might be employed as a natural sugar substitute. The aim of the present study is to employ ultrasound waves to optimize the extraction process from the leaves of Stevia Rebaudiana and use High Performance Thin Layer Chromatography (HPTLC) to analyze the extract.
Water, water-methanol mixture, methanol, water-ethanol mixture and ethanol was applied for extraction as solvent. The extraction was carried out by soxhlet and ultrasound waves at various times and power condition according to the official procedures.
The results indicated that water was the most suitable solvent among the solvents employed. The results also showed that the application of ultrasound with power of 90 W for 2 minutes resulted better extraction (811.61 g/mlμ) as compared to the soxhlet method (795.70 g/mlμ).
The present study indicated that ultrasound application might be a suitable, fast and safe method for extraction of Stevioside sweetener from Stevia Rebaudiana.

Reference trajectory tracking and guarding against system disturbances and uncertainties are the important factors in the realm of lower limb exoskeleton robots control. Sliding mode PID is one of the robust controllers, which has a sliding manifold in the form of the PID controller. Chattering is the substantial predicament of the PIDSMC so that boundary layer around the sliding manifold is applied to eliminate the phenomenon. In this step, not only the chattering phenomenon is not eliminated but the robustness of the controller is also mitigated. In this study, supper twisting PID sliding mode controller (STPIDSMC) was used to eradicate the chattering phenomenon and enhancing controller robustness. The STPIDSMC robustness is protected indigenously and without defining the boundary layer, and the chattering phenomenon is reduced. Furthermore, to meet the external disturbances and uncertainties with unlimited amplitude, adaptive active force control method is combined by STPIDSMC as a modifying input control loop. In the active force control approach, the control input is online modified based on the estimation of moment inertia of the robot links. In order to accomplish maximum performance, control parameters were optimized using harmony search algorithm. In the optimal state, the performance of the proposed controller has been compared with PIDSMC and STPIDSMC that revealed the priority of the proposed controller rather than other controllers. The results indicate that the three error criteria, ITAE, ITASE, and IASE experience significant reduction about 39, 48, and 66 percent respectively compared to STPIDSM.

Estimating the costs of blasting operations is an important parameter in open-pit mining. Blasting and rock fragmentation depend on two groups of variables. The first group consists of mass properties, which are uncontrollable, and the second one is the drill-and-blast design parameters, which can be controlled and optimized. The design parameters include burden, spacing, hole length, hole diameter, sub-drilling, charge weight, charge length, stemming length, and charge density. Blasting costs vary depending on the size of these parameters. Moreover, blasting brings about some undesirable results such as air overpressure, fly rock, back-break, and ground vibration. This paper proposes a mathematical model for estimating the costs of blasting operations in the Baghak gypsum mine. The cost of blasting operations in the objective function is divided into three parts: drilling costs, costs of blasting system, and costs of blasting labours. The decision variables used to minimize the costs include burden, spacing, hole diameter, stemming length, charge density, and charge weight. Constraints of the model include the boundary and operational limitations. Air overpressure in the mine is also anticipated as one of the model constraints. The non-linear model obtained with consideration of constraints is optimized by simulated annealing (SA). After optimizing the model by SA, the best values for the decision variables are determined. The value obtained for the cost was obtained to be equal to 2259 $ per 7700 tons for the desired block, which is less than the blasting costs in the Baghak gypsum mine.

The purpose of this study was to assess some heavy metal (HM) concentrations in the soil and atmospheric falling dust along the Yazd highway, Yazd Province, Iran. The total concentrations of cadmium (Cd), cobalt (Co), copper (Cu), nickle (Ni), lead (Pb), zinc (Zn), iron (Fe) and manganese (Mn) in the dust and soil samples were measured using atomic absorption spectrophotometry after digestion with acid. The relationship between HMs in the falling dust was determined using correlation coefficients, principal component analysis and cluster analysis.  The mean concentrations of HMs in falling dust were higher than those of the nearby soils, except for Fe, Pb and Zn. The highest correlation between HMs in the falling dust and soil was associated with Cd and Fe as well as Cd and Ni with the correlation coefficients of 0.81 and 0.97, respectively. Based on the principle component analysis, cluster analysis and correlation coefficients, two resources were identified for HM concentrations in the falling dust. The measurement of enrichment factor exhibited that the region dust infiltration of metals on Mn (13.46), Zn (8.16) and Cu (5.21) are grouped in the severe enrichment class. Increasing industrialization and human activities lead to enter intensified levels of HMs into atmosphere. So, implementation of environmental standards and improvement of public transportation are necessary to reduce the level of pollutants entering the atmosphere.

Since it is too vital to the prevention of carotid disease in the vascular system, it seems necessary to the estimation of the elastic behavior of the carotid artery in head and neck external radiotherapy. In the present study, a total of 24 neck carcinoma patients treated with external radiotherapy had been studied. The carotid mean dose values were determined for each case by contouring the common carotid artery in consecutive CT scan images. Ultrasonography was performed from the wall region of each subject before and after the radiotherapy process. The instantaneous changes of intima-media thickness and radial movements in the arterial wall were extracted by the implementation of a maximum gradient algorithm. The results indicate that the normalized rate of absorbed dose of carotid from prescriptive dose is about 0.82±0.24. Moreover, the normalized value of Young modulus of radiation-induced carotids compared to non-irradiated carotid arteries along with increasing the intima-media-thickness is 1.58±0.21. These changes may be lead to stroke symptoms in the future.

A suitable method of locating an underground dam according to physiographic factors ensures its operation in providing water resources for hot and dry areas without causing environmental issues. In this study, Remote Sensing (RS), and Geographic Information System (GIS) techniques were used to locate suitable locations for underground dams. To implement, several data layers; topography, slope, lithology, drainage, lineaments, and local Qanats of the region were collected using the Digital Elevation Data (DEM), and LANDSAT 7 ETM Satellite. The lithological layers were gained by means of a geological map of the 1/100000 of Natanz in Kashan plain. Regional lineament data were calculated and converted to a digital layer by applying directional filters on the ETM satellite data in four directions using ENVI (remote sensing software). A supervised classification tools in ENVI software were then used for mapping the lithological layers. Final map of the most suitable locations for the construction of an underground dam was prepared by weighting of the layers with the method of Analytical Hierarchy Process (AHP combined with the support of Weighted Overlay tool in a GIS. Following identifying the areas with high priority, seven convenient points were identified by visiting the area taking into account the accessibility, and the performances of the region. Of these, four points to reserve subsurface water, one point to increase watering of Qanats and two points to prevent reduction of subsurface water quality were selected.

Organic solar cells OSCs have attracted great interest due to their low cost, light weight, and flexibility. However, their efficiencies still need to be improved for many practical applications. The most conventional electrode for OSCs is indium tin oxide ITO which does not present high flexibility and robust mechanical properties. Additionally, this material is not appropriate for mass production due to the limited indium reserves. Here, we have proposed nanohole array-based plasmonic silver electrodes in order to design ITO-free OSCs. Numerical simulations based on finite-difference time-domain FDTD method have been employed to minimize the reflectance of the OSC while increasing the photoactive layer absorption. The designed nanostructure is a great potential to realize large-area and flexible energy harvesting.

In the wind tunnels, the balance measurement instrument is used to measure six components of force and moment on an airplane model. The balance of measurement consists of two parts of the balance structure and electronic equipment. In this research, a mechanism with flexible hinges is designed to achieve the desired configuration of the balance structure. In the process of designing the geometric structure of this mechanism, an effective arrangement has been implemented for the six load cell - flexure columns. The advantages of flexible hinges in comparison to conventional hinges are the absence of friction, compactness and its linear behavior. The reaction effects of the components of force and moment on each six load cell - flexure columns created the coupling errors. One of the main sources of this kind of error is related to the structure of the balance mechanism. The reason for this type of error is the inadequacy of the axial flexibility to the lateral flexibility of the columns. The aim of this research is to optimize the design of the flexible mechanism in order to achieve the minimum coupling error of the structure. For this purpose, hinge design considerations and analytical equations of the flexible mechanism have been extracted. The design of the balance mechanism is optimized by creating a structure coupling error matrix. To validate the analytic equations and results, the problem is compared with the finite element analysis. The results indicated that the measurement errors decrease in the measurement of six components of force and moment of balance.

Economic growth is one of the main development goals in human societies. In the path of growth and rising incomes, necessary resources to implement the strategic plans of the society provided. One of the key programs and important issues of public funds is improving public health and environment protection. But there is no clear evidence, that economic growth improves the public health and environmental quality. Given that economic growth can be combined with the destruction of the environment on the one hand and on the other hand, in unhealthy environment, public health is at risk. According to the importance of these issues, Investigation this topic is very important. This study aimed to examine this relationship in selected countries with using GMM method during the period 1990-2013. The results of the model indicate that economic growth is associated with public health and environmental degradation. Other fore the environment quality negatively effect on health. Also cross-contamination effect of economic growth and environmental degradation on public health is negative and significant and that means the positive benefits of economic growth on public health, be dilute. Therefore, in view of the negative pollution impact on the health, the environmental quality is important, so environmental Protection to achieve sustainable development should be considered. The results of this study suggest that economic growth is associated with improvements in public health, but will also lead to environmental degradation. As well as reducing the quality of the environment affect a significant and negative impact on public health in the countries affected. Thus, environmental concerns of economic growth in terms of the negative impact on health and waste health costs double and attention to maintain the quality of the environment in order to achieve sustainable development is emphasized.

In this study, the effect of a cylindrical protuberance on the thrust vector of a supersonic jet was investigated as a new method in thrust vector control. For this purpose, a convergent-divergent (C-D) nozzle was designed and constructed. This nozzle is such that the Mach number is its nominal output in full expansion conditions 2. The wall of the nozzle is equipped with pressurized holes to measure pressure variations. Also, there is a duct wall in the nozzle wall to apply a protuberance inside the nozzle. Pressure sensors are used for pressure measurement and also the schlieren system IS used to check the outlet flow field. The total pressure of the compartment is constant at all tests and is 5.7 bar. The results of this study show that the depth of penetration of the protuberance in the flow field has a significant effect on the amount of deviation and even the direction of the deviation of the jet stream exited from the C-D nozzle. The maximum jet outlet flow from the nozzle is 5.7 degrees, which occurred at a rate of H/D*=0.4. In addition, these results indicate that with the increase in bulge penetration within the nozzle, the nozzle axial thrust has slightly decreased.

In this study, the effect of a cylindrical protuberance on the thrust vector of a supersonic jet was investigated as a new method in thrust vector control. For this purpose, a C-D nozzle was designed and constructed. The nozzle exit Mach number is 2. The wall of the nozzle is equipped with pressure holes to measure pressure variations. Also, there are several holes in the divergence portion of nozzle wall to apply a protuberance inside the nozzle. Pressure sensors for pressure measurement and also the Schliern system are used to check the outlet flow field. The nozzle pressure ratio in all experiments is constant and in two cases is equal to NPR=6.6 and NPR=9. The protuberance is installed in the nozzle divergence section, at position X⁄L=0.6,0.7,0.8,0.9 and with a constant penetration ratio of H⁄D^* =0.2. The results of this study show that using the protuberance can control the angle of the thrust vector. Also, installing location X⁄L=0.9 is the best position which, in this case the angle of the trusted vector reaches 3.1 degrees. Also, the results reveals that the change in the nozzle pressure ratio in different installing positions has different effects on the thrust vector angle and axial thrust losses.

The purpose of this study was to investigate the ability of Mondell Pine tree) Pinus eldarica (in decreasing heavy metal contaminants within the environment by determining the concentration of heavy metals in the leaves and bark of P. eldarica and comparing their concentrations on falling dust. to reduce the concentrations of heavy metals in the environment compared with the concentration of these pollutants in falling dust. After the preparation of falling dust and plant samples, the heavy elements of them have been extracted by acid digestion method and then measured by flame atomic absorption spectrophotometry. The results showed that the concentration of Iron, Manganese, Zinc, Lead, and Cadmium in falling dust respectively were the highest to the lowest. Concentrations of Cadmium, Iron, Cobalt, and Nickel, increased with increasing distance from the road due to multi-directional winds and the presence of other contaminants. The Pearson correlation analysis between heavy metals found in the falling dust and Mondell Pine tree showed that the input and controlling factors of these elements in the Mondell Pine tree are probably the same as the dust. The results showed that the P. eldarica bark with the amount of accumulation index of 7261 mg/kg has more ability to simultaneously absorb different metals. As a result, since this green belt surrounds the Yazd urban area, it is hoped that a significant amount of heavy metals will be absorbed by these trees.

In this paper application of the multipoint aerodynamic model for parameter estimation in spin maneuver as a high-angle-of-attack and high-angular-rate fight regime was concentrated. The identification technique used to illustrate the approach is maximum likely hood with the equation error approach. The multipoint model comprises a set of new parameters describing the aerodynamic force distribution along individual surface components of the aircraft so using this method will be useful for spin aerodynamic modelling. The aim of this study is to demonstrate that this model allows coupling among the three force and three moment components, this means that the parameters associated with the six-component equations are thus treated simultaneously. Another advantage of this approach is that the model allows each individual force generating surface element of the aircraft to contribute independently to the total force and moment rather than some average of these contributions relative to the center of mass. The method is applied to measurements from spin fight test data conducted with a light general aviation aircraft and the results compared with conventional aerodynamic model. The results indicate that the method is capable of reproducing, with reasonable accuracy, the force and moment measurements obtained from a fight other than the one used in the parameter estimation.

In this study, the effect of a cylindrical protuberance on the thrust vector of a supersonic jet was investigated as a new method in thrust vector control. For this purpose, a convergent-divergent nozzle was designed and constructed. This nozzle is such that the Mach number is its nominal output in full expansion conditions 2. The wall of the nozzle is equipped with pressurized holes to measure pressure variations. Also, there is a duct wall in the nozzle wall to apply a protuberance inside the nozzle. Pressure sensors for pressure measurement and also the schlieren system are used to check the outlet flow field. The total pressure of the compartment is constant at all tests and is 5.7bar. The results of this study show that the depth of penetration of the protuberance in the flow field has a significant effect on the amount of deviation and even the direction of the deviation of the jet stream exited from the convergent-divergent nozzle. The maximum jet outlet flow from the nozzle is 5.7degrees, which occurred at a rate of H/D*=0/4. In addition, these results indicate that with the increase in bulge penetration within the nozzle, the nozzle axial thrust has slightly decreased.

Oil leakage causes soil contamination and induces changes in the physical and mechanical properties of soils. In areas contaminated with oil products such as gasoline, the implementation of civilian operations requires determination and prediction of soil behavior in the existing conditions. In this research work, the effect of oil contamination by gasoline obtained from the National Oil Company in the Yazd Province is considered to investigate the effect of contaminants on the geotechnical properties of fine-grained sand. In order to examine the geotechnical characteristics of contaminated soil, compaction, undrained triaxial (CU), and consolidation tests are conducted. The tests are carried out on the samples of clean soil and contaminated soil with 1, 3, and 5% gasoline. The results obtained show that added gasoline reduces the optimum moisture content and increases the maximum dry density. In addition, based on the results of the triaxial test, the amount of friction angle and the cohesion of clay sand decrease by 21% and 14% with increasing contamination up to 5%, respectively, compared to the clean soil sample. Furthermore, adding gasoline significantly increases the compressibility and compression index.

Recently, significant interest has been attracted by the potential use of aluminum nanostructures as plasmonic color filters to be great alternatives to the commercial color filters based on dye films or pigments. These color filters offer potential applications in LCDs, LEDs, color printing, CMOS image sensors, and multispectral imaging. However, engineering the optical characteristics of these nanostructures to design a color filter with desired pass-band spectrum and high color purity requires accurate optimization techniques. In this paper, an optimization procedure integrating genetic algorithm with FDTD Solutions has been utilized to design plasmonic color filters, automatically. Our proposed aluminum nanohole arrays have been realized successfully to achieve additive (red, green, and blue) color filters using the automated optimization procedure. Despite all the considerations for fabrication simplicity, the designed filters feature transmission efficacies of 45-50 percent with a FWHM of 40 nm, 50 nm, and 80 nm for the red, green, and blue filters, respectively. The obtained results prove an efficient integration of genetic algorithm and FDTD Solutions revealing the potential application of the proposed method for automated design of similar nanostructures.

The purpose of the present study was to analyze the qualitative content of research related to the concepts of entrepreneurship ecosystem and start-ups. For this purpose, sources published between 2010 and 2019 (85 sources) were selected and reviewed. The results of the content analysis led to the separation of seven dimensions related to the entrepreneurial ecosystem. Dimensions were: Entrepreneurial Ecosystem Dimensions, Entrepreneurship Development Policies, Entrepreneurial Problems and Barriers, Entrepreneurial Ecosystem Success Prerequisites, Entrepreneurial Ecosystem Stakeholders, Entrepreneurial Development Strategies and Entrepreneurial Ecosystem. Other research results indicated that about 40% of the resources surveyed had quantitatively studied the entrepreneurial ecosystem. Most of the resources were implemented by organizations, targeting 40% of resources for managers, entrepreneurs and business owners. Data were collected through a questionnaire in half of the sources. In terms of geographical distribution, most sources at the international level have examined the dimensions of the entrepreneurial ecosystem. In addition, a review of the year of publication of the published sources revealed that during the 10 slides, there was an increasing trend in selected sources in the field of entrepreneurship ecosystem.

In this study, the effect of single and dual-frequency sonication on cell death of B16-F10 melanoma cells is investigated at constant temperature. Here, 20 groups were studied. The test groups consisted of: control and sham, 40 kHz (intensity: 0.24 W/cm2), 1 MHZ (intensity: 0.5 W/cm2) and the dual frequency groups which each frequency group included seven subgroups of 30, 120, 60, 150, 300, 600 and 1200 s. Cell viability was measured by MTT assay. The result demonstrated that the cell viability for 40 kHz with 30 s sonication time was 96%, which decreased to 6% by increasing the sonication time up to 1200 s. In dual frequency, cell viability decreased in all subgroups, and its amount ranges from 95% at a sonication time of 30 s to 3% at 1200 s sonication time. The same process happens for 1 MHz frequency with a lower relative slope (97% to 15% when sonication time increased from 30 s 1200 s). Ultrasound waves caused the B16-F10 melanoma cell death in constant temperature. Dual frequency sonication caused more cell death especially at higher sonication time, possibly due to cavitation.

External disturbances and internal uncertainties with an unknown range, as well as the connection between the human body and robot, are major problems in control and stability of exoskeleton robots. In order to deal with disturbances and uncertainties with the known range of the system, the sliding mode controller is used as a robust approach. The chattering phenomenon is one of the drawbacks of sliding mode controller, which boundary layer is employed to reduce the effects of this phenomenon. In this case, not only the chattering phenomenon is not completely eliminated, but the robust characteristics of the controller are mitigated. In this paper, in order to cope with the disturbances and uncertainties with unknown range, and guard against chattering as a key ingredient of excessive energy consumption and convergence rate reduction, optimal adaptive high-order super twisting sliding mode control has been applied. The dynamic model of a lower limb exoskeleton robot is extracted using the Lagrange method in which four actuators on the hip and knee joints of the left and right legs are considered. To achieve optimal performance, controller parameters are determined using Harmony Search algorithm by minimizing an objective function consisting of ITAE and control signal rate. The proposed controller performance is compared with optimal adaptive supper twisting sliding mode and optimal sliding mode controllers which shows the superiority of the optimal adaptive high-order sliding mode controller rather than other designed controllers.

Inroduction & Objective: Passiflora caerulea is one of medicinal plants that has contained high antioxidant combinations and are useful in curing epilepsy, diarrhea, burn, Hemorrhoid and in regulating liver enzymes. The objective of this study was evaluation of effect of passiflora caerulea leaf Hydro-alcoholic extract on some biochemical factors in adult male rat. Material and Method: In this experiential study, 40 wistar male rats, about 195-200 g each were used in five groups eight including : control (without received nothing), sham group (received distilled water) and 3 experimental groups receiving 150,300,600, mg/kg leaves of passiflora caerulea Hydro-alcohol extract respectively during 21 days. After the end of this period, blood samples were taken from the heart to measure the biochemical factors (urea, creatinine, albumin, total protein). The results were analyzed using SPSS software and comparison of meanings was done using T. test.  The results showed that the amount of albumin in the experimental group receiving 600 mg / kg of the extract decreased significantly compared to the control group. Total protein, cratinin and total body weight had no significant changes with control group. Hydro-alcoholic extracts of Passionate flower leaf caused reduction of blood urea nitrogen levels in all experimental groups receiving the extracts as compared to the control. According to the results of this study, it can be argued that the Passionate flower plays a supporting role for the liver, and the lack of liver damage in the rats indicated this issue.

 Nurses, as one of the main sources of organizational knowledge and main elements of knowledge transfer in hospitals, can play a key role in organizational learning process. The present study was performed due to the importance of organizational learning capabilities of nurses.  This study aimed to investigate the effectiveness of decision-making through brainstorm on organizational learning capability in nurses.
Material and  This study was conducted in two stages: In the first stage, learning capability of all nurses in internal-surgical section (18 departments) of Baqiyatallah Hospital was measured by census method (281 persons). In the second stage, eight sections with no significant differences in organizational learning were determined and randomly divided into test and control groups. A theoretical and practical training workshop was held to train other personnel and head nurses how to implement the brainstorming method for decision making. Then, after four months, the Organizational Learning Questionnaire was distributed in control and test groups. Data analysis was done through descriptive statistics including mean±standard deviation (SD) and analytical statistics including Chi-square, Mann-Whitney, Wilcoxon, T-test and ANOVA using SPSS.19.  The results of the first stage showed that the mean of total score for organizational learning capability of nurses was 58.04 (8/98), which according to Likert scale, was average. Also, the mean of scores for areas of management commitment, system and knowledge transfer was 19.02 (33.23), 11.44 (1.88) and 13.67 (3.05), respectively which was average, while that was 13.89 (2.80) for the fields of open space and experiment, which was at the lowest level. The results of the second stage of the study showed that the meanof total score in entire area of organizational learning capability in nurses increased and was significantly different before and after running the intervention and brainstorming in the test group.For example, the standard deviation of the entire organizational learning capability in nurses was p = 0.012 after the intervention. Also, the standard deviation of areas of management commitment,, System Attitude and knowledge transfer was p=0/044, p=0/000, and p=0/003, respectively, that were all significant, but no difference was observed in the control group. Discussion and Conclusion:  According to the results of this study and the effectiveness of brainstorming method on boosting the organizational learning capability of nurses and improving the quality of nursing care and nursing services, it is recommended that the nursing managers implement this method in health care departments.

Coating of fabrics with spectrally selective nanopigments, in order to manipulate their optical properties, has been introduced in recent years. This method presents a new field in high performance textiles which covers high technological aspects such as UV protective fabrics, Solar cells and cool fabrics as well. One of the most important approaches in prediction of reflectance factor of coated fabrics is based on Discrete Ordinate Method (DOM), namely, Kubelka-Munk or Multi Flux Model, where the fabric is considered as a continuous medium consists of a dispersion of nanopigments. However, ignored surface scattering on interfaces causes considerable error. Geometric optic, on the other hand, is utilized widely for prediction of spectral behavior of particles with very large dimension compared with incident wavelength. The model lacks limitation of DOM but is not appropriate for nanopigments of small diameters. According to the fact that, coated fabrics are systems consists of nano and micron sized materials, a theoretical model is proposed in which radiative properties of micro particles are described using Geometric Optic, and those for nano and submicron sized particles are described using Mie scattering theory. Subsequently, the experimental realization of proposed model has been conducted on Titanium dioxide nanopigments coated on polyester fabrics, and the successful comparison of the proposed model with experimental results confirms its suitability, and introduces a rather new procedure in the field of radiation transfer through mixed beds of elements with extremely different sizes.

To study the effect of plant density on some morphological traits, oil percent, yield and yield components of sunflower cultivars, an experiment was conducted at Research Field of Birjand branch Islamic Azad University, Iran in 2009 as a split-plot experiment arranged on a randomized complete blocks design with three replication. In this research main plots were sunflower cultivar in four levels (Progres, Hisan 36, Zaria and Star) and sub-plots were plant density in three levels (5, 7.5 and 10 plants m-2). The results indicated that the effect of cultivar on morphological traits, yield and yield components and oil yield were significant. Also, all mentioned traits and oil percent were significantly affected by plant density with exception on leaf number per plant. Mean comparison also indicated that Progres cultivar was significantly superior for plant height, stem diameter, leaf number per plant, head diameter, 100- seed weight and harvest index as compared with other cultivars. Also, increased density from 5 to 10 plants m-2 increased plant height and yields of seed, biological and oil, 13.2, 49.5, 67.5 and 64.8 % respectively, but significantly decreased seed number per head, 100-seed weight and harvest index, 14.8, 12.8 and 8.6 %, respectively. Overall, it is recommended to use Progres cultivar with the density of 10 plantsm-2 for the cultivation of sunflower under the conditions of this study.