the largest class of algebraic hyper structures satisfying the module like axioms is the v h -module. in this paper, we consider the category of v h -modules and prove that the direct limit alwaysexists in this category. direct limits are defined by a universal property, and so are unique. the mostpowerful tool in order to obtain a module from a given v h - module is the quotient out procedure....

the main problems in mixed culture are using the agricultural machines for plant two or more crop simultaneously. in the present study to remove difficulties of using agriculture machinery in planting operation for corn and bean simultaneously, a planter was designed and developed to direct planting of two different types of seeds having different shapes and sizes with precise proportion and di...

Longleaf pine is a highly desirable species, resisting fire, insects and pathogens, and produces quality solid-wood products, but regeneration of the species has been difficult. Natural regeneration is feasible only on a small portion of the area considered to be longleaf pine type. Therefore, artificial regeneration must become a reliable means of regenerating the species if restoration of the...

In this study, enzyme activities and their relationships to organics purification were investigated in three different vertical flow constructed wetlands, namely system A (planting Pennisetum sinese Roxb), system B (planting Pennisetum purpureum Schum.), and system C (no plant). These three wetland systems were fed with simulation domestic sewage at an influent flow rate of 20 cm/day. The resul...

Crop planting suitability evaluation is important for agricultural production. In this study, a comprehensive evaluation framework which combined geographical information system, remote sensing, global position system and geostatistics with other models was presented to evaluate the tobacco planting suitability on a small scale. Ten indicators from three respects of climate, terrain and soil nu...

This study aimed to evaluate the efficiency of energy consumption and economic analysis of different watermelon cultivation systems in Fars Province of Iran. Watermelon production systems were classified into five systems, namely, custom tillage (group 1), conservation tillage (group 2), traditional planting (group3), semi mechanized planting (group 4), and mechanized planting (group 5). Data w...

In China, the ridge-furrow water conservation planting (RC) system is advantageous for improving crop yields and rainwater use efficiency. In RC planting system, plastic film-mulched ridges are employed for water harvesting while the furrows serve as infiltration and planting belts. To optimize the RC system and to overcome problems due to the lack of water in semi-humid areas at risk of drough...

The use of water resources should be restricted until a suitable irrigation and planting system is developed in the North China Plain. This study was aimed to study the effects of planting pattern and irrigation on the farmland microclimate, and indentify possible ways to improve the yield of winter wheat. The field experiments in a randomized complete block design with four replicates were con...