Background and Objectives: Nowadays, study about the reclamation of abandoned skid trails is necessary due to their frequency in forestry units of north of Iran especially in so-called respiration period. These skid trails turn to be bare after the primary transportation (especially within first transportation years) where resulted in erosion and damage to soil forest. The aim of this study was to determine the best conservation treatments to deal with skid trails’ water erosion. Materials and Methods: Firstly, a skid trail with a minimum length of 500 meters was selected in Bahramnia’ s forestry plan. The longitudinal slope was divided into slope classes of 20-40% and >40%. In each class a segment with a length of 126 meters was determined and treatments of ditch & embankment, ditch & slash and ditch & stone each of in length of 14 meters with 5 meters interval were implemented. A rubber bar was installed at the end of each segment to convert sediment and runoff in to collectors. Sampling was done after each rainfall during 4 months (autumn and winter 2019 and 2020). The Intensity – Duration rainfall information has been determined using Rain gauge in the study area, then dry weight of sediment samples has been measured in laboratory. Results: Findings indicated that in both slope classes of 20-40% and >40% amount of runoff, sediment concentration and soil loss was significantly increased along with increasing intensity and duration of rainfall. In slope class of 20-40%, skid trail treated by ditch and slash was better than other treatments in sedimentation and soil loss control. In slope class of >40%, there wasn’ t significant difference between the efficiency of treatments in sediment and soil loss control. Whereas, generally, treatments of ditch and slash as well as ditch and stone were more successful to control soil erosion than ditch & embankment treatment. In both slope classes, the rainfall intensity of 0. 11 mm h-1 (2. 64 mm in 24 h) was the threshold of water erosion of soil on skid trails. Likewise, the interaction effect of slope and treatment type was not significant on runoff volume’ s variables as well as sediment concentration and soil loss. Findings indicated that the ditch & slash treatment, in slope class of 20-40%, were the best in terms of sedimentation and soil loss control which could mitigate soil waste by 64%. In unallowable slope >40% all treatment could mitigate soil erosion by 47% which indicates the low efficiency of conservational treatments in unallowable slope tracks. Conclusion: This research showed that ditch & slash treatment can reduce soil erosion in skid trails, so given to conservation this treatment can be used in other regions of the Hyrcanian Forest to protect skid trail against soil erosion.

In this paper, the nonlinear regression models when the model errors follow a slash skew-elliptical distribution, are considered. In the special case of nonlinear regression models under slash skew-t distribution, we present some distributional properties, and to estimate their parameters, we use an EM-type algorithm. Also, to find the estimation errors, we derive the observed information matrix analytically. To describe the influence of the observations on the ML estimates, we use a sensitivity analysis. Finally, we conduct some simulation studies and a real data analysis to show the performance of the proposed model.

Background and Objectives: Lateral ditches which are constructed to drain surface flow and protect the road structure under the severe rainfall are eroded by runoff velocity and then sediment as suspended load are transmitted to the river and aquatic ecosystem. Therefore, use of the cost effective, efficient and environmental techniques is essential for protecting ditches. The objective of this research was to compare the effect of different protective treatments on reduction of sediment yield from the ditch of forest roads as well as the assessing the effect of flow intensity on sediment concentration. Materials and Methods: At first a reach of lateral ditch with a total length of 50 meters was selected along the main roads of district one in the Bahramnia forestry plan in Golestan Province. The longitudinal slope (5% with dimension of 30 × 50 cm) and soil type (texture, porosity and moisture) of selected reaches were same. Five sub-reaches (treatments) each of with a length of 10 meters were considered for establishing the protective treatments including riprap, grass cover by Festuca, cotton geotextile, picket and wattle by local slash and control. Flow simulation was done for ten minutes at two flow rates of 5 and 10 L S-1 using a tank with capacity of 6000 liters equipped with motor-pump. Sediment sampling from the runoff was carried out at the end of each sub-reach every minute. Samples were transported to the laboratory and there sediment concentration was calculated in gram per liter. Runoff flow velocity in different treatments was measured using an electromagnetic flow meter. Results: Sediment concentration and runoff velocity in treatments of riprap, grass cover by Festuca, cotton geotextile, picket and wattle by local slash was significantly lower than that of control. Increasing flow rate from 5 L S-1 to 10 L S-1 caused no significant change in sediment concentration (except for control and riprap treatments) and runoff velocity (except for control and cotton textile treatments). Sediment yield from riprap and control treatments under the flow rate of 10 L S-1 was significantly higher than that of 5 L S-1. Moreover, runoff velocity from cotton textile and control treatments under the flow rate of 10 L S-1 was significantly higher than that of 5 L S-1. Conclusion: Treatments of picket and wattle, riprap, grass cover by Festuca and cotton geotextile in ditch with low flow rates (5 L S-1) and treatments of cotton geotextile, picket and wattle with local slash in high flow rate (10 L S-1) can be used for a forest road with dimension 30 × 50 cm, slope 5%, clay soil with porosity 57% because of their high efficiency in reducing sediment yield and runoff velocity.

Oxidation ditch process is used to treat the municipal and domestic sewage. The untreated sewage generates fouling smell, harmful bacteria, etc. which is hazardous for public health and degrades the environment by librating noxious gases. This paper examines the use of curved blade aerator for oxidation ditch process. The rotor, which controls the aeration, is the main component of the aeration process. Therefore, the objective of this study is to find out the variations in overall oxygen transfer coefficient and aeration efficiency for different configurations of aerators by varying the parameters like speed of aerator, depth of immersion and blade tip angles so as to yield higher values of overall oxygen transfer coefficient and aeration efficiency. Four aerators of different configuration were developed and fabricated in the laboratory and were tested for above mentioned parameters. A mathematical model is developed for predicting the values of kLa and aeration efficiency which has R2 values of 0.97 and 0.99 for experimentally determined and calculated values. In laboratory studies, the optimum value of overall oxygen transfer coefficient and aeration efficiency were observed to be 10.33/h and 2.269 kg O2/kWh for aerator speed of 48 rpm, 5.5 cm depth of immersion and 47o blade tip angle for curved blade aerator.

Skidding logs from stump to depot areas is the most important part of ground-based logging operations, which often leads to an increase in soil bulk density and decrease in soil porosity. In this study, woody slash and sawdust treatments with a weight of 10 kg m-2 were used to decrease soil compaction on skid trails during the trips of rubber-tired skidder To f E655 in compartment of 29 in Bahramnia forestry plan in Gorgan, Golestan province. Soil samples were collected by steel cylinder from 0-10 and 10-20 cm soil depths after 2th, 6th, 10th and 16th skidder trips on treated and control plots. Bulk density, porosity percentage and moisture content were measured in laboratory. Results showed the soil bulk density of 1.05, 1.12, 1.18 and 1.2 g cm-3 at the depth of 0-10 cm in bare soil after two, six, ten and sixteen trips. On trails treated by sawdust protective layer, the soil bulk densities were 0.98, 1.02, 1.07 and 1.09 g cm-3. These values for slash treatment were 0.64, 0.98, 1.05 and 1.07 g cm-3, respectively. The soil bulk densities after two, six, ten and sixteen trips were 1.31, 1.38, 1.43 and 1.45 g cm-3 at the depth of 10-20 cm in bare soil. By using sawdust these values decreased to 1.22, 1.26, 1.31 and 1.32 g cm-3, whereas the use of slash resulted in 1.18, 1.21, 1.28 and 1.31 g cm-3, respectively. The results indicated better performance of slash treatment in reducing soil compaction compared to sawdust treatment. Moreover, soil porosity at the both depths of treated plots by woody slash was more than that of other treatments and was near to forest soil porosity. Furthermore, sawdust treatments could more retain the soil moisture compared to slash treatment. Using coverage material in skid trails was concluded to reduce of destructive effects of skidder transport.

Computer games are a combination of the arts of cinema, graphics, music, literature, and their subsets that, despite having an applicant and a consumer, have not been considered in Iran in terms of production for various reasons. However, by adapting literary works as the axis of creative ideation in connection with the narration of computer games, a more effective platform can be created in the production of such products. Therefore, in the present study, the aim was to investigate this issue by a descriptive-analytical method, relying on the desirable features of classical Persian literature that has a range of epic works and texts such as Borzounameh and similar examples. The question posed in this study is: What are the characteristics of existence, multiplicity, and diversity that make adaptation desirable for computer games with an indigenous culture approach and considering appropriate value-ethical norms? It seems that features such as the presence of a compelling story and lively narrative, the presence of a hero (anti-hero), and the multiplicity of attractive characters with the ability to interact in the context of various conflicts and image-based expression of appropriate themes in epic works have turned these types of texts into desirable options for adapting computer games with a loyal approach and with small changes appropriate to the age and culture of the target audience in the widely-used martial-combat genre.

Fire is widely used to clear farms in Iran, while there is little information regarding the effects of fire on the characteristics, especially mineralogy of soils. The objectives of the present study were to 1) compare some physico-chemical properties of burned and unburned soils and 2) evaluate minerals transformation in top soil layer resulting from increasing temperature. Soil samples were taken from 0-5 and 5-15 cm depths of two burned places, an agricultural soil from Takht-e-Jamshid area and Bamoo forest, in four replications. Physico-chemical analyses were carried out on burned and unburned samples. X-ray diffraction technique was used to identify minerals of clay fraction in 0-5 cm depth burned and unburned soil, and also to compare transformation of minerals (if any) after heating at 300oC and 600oC for 2, 4, 8 and 12 h. Burning increased soil pH and sand sized fraction in 0-5 cm, and P and K in both depths of Bamoo forest. Changes in soil properties of agricultural filed were negligible. XRD analyses showed the reduction in the intensity peaks of chlorite and illite after burning. Lower relative quantity of chlorite and illite was observed in various times of 300oC treatment in comparison to control, while they were not observed in 8 and 12 h of 600oC. No change was observed in the peak of quartz in forest and field soils after burning and after various heat treatments.