نتایج جستجو برای: Ecological systems؛ Indefinite weight؛ Grazing and constant yield harvesting؛ Sub-supersolution method

تعداد نتایج: 17299149  

In this paper, using sub-supersolution argument, we prove an existence result on positive solution for an ecological model under certain conditions. It also describes the dynamics of the fish population with natural predation and constant yield harvesting. The assumptions are that the ecosystem is spatially homogeneous and the herbivore density is a constant which are valid assumptions for mana...

Journal: :Bulletin of the Belgian Mathematical Society - Simon Stevin 2010

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شهید بهشتی - دانشکده علوم 1371

we describe here a suitable approach for the synthesis of n-unsubstituted monocyclic b-lactams under mild reaction conditions by the annelation of imines with substituted acetylchlorides. in this method the reaily available phtalimidoacetyl chloride were allowed to react with - dibenzylideneiminotoluene (hydrobenzamide) in the presence of an equimolar amount of triethylamine in refluxing toluen...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شاهد - دانشکده فنی و مهندسی 1387

abstract biometric access control is an automatic system that intelligently provides the access of special actions to predefined individuals. it may use one or more unique features of humans, like fingerprint, iris, gesture, 2d and 3d face images. 2d face image is one of the important features with useful and reliable information for recognition of individuals and systems based on this ...

پایان نامه :دانشگاه آزاد اسلامی - دانشگاه آزاد اسلامی واحد تهران مرکزی - دانشکده مدیریت 1392

data envelopment analysis (dea) is a powerful tool for measuring relative efficiency of organizational units referred to as decision making units (dmus). in most cases dmus have network structures with internal linking activities. traditional dea models, however, consider dmus as black boxes with no regard to their linking activities and therefore do not provide decision makers with the reasons...

جلیلیان, جلال, پیرزاد, علیرضا, کوه نورد, پریناز,

To evaluate the effect of micro-nutrients spraying on some agronomic characteristics of the safflower (Carthamus tinctorius L. cv. Isfahan landrace), under different cropping systems, an experiment was carried out as split plot based on randomized complete block design with three replications in 2011. Experimental treatments were including: cropping systems (high, medium, low input and ecologic...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه تربیت مدرس - دانشکده فنی 1391

the study of air infiltration into the buildings is important from several perspectives that may be noted to energy and design of hvac systems, indoor air quality and thermal comfort and design of smoke control systems. given the importance of this issue, an experimental and numerical study of air infiltration through conventional doors and windows has been explored in iran. to this end, at fir...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه علوم پایه دامغان 1389

in this thesis, ‎‎using‎‎ ‎concept‎s‎ ‎of‎ ‎wavelet‎s‎ ‎theory ‎‎‎som‎e‎ ‎methods‎‎ ‎of‎ ‎th‎e ‎solving‎‎ ‎optimal‎‎ ‎‎con‎tr‎ol‎ problems ‎(ocps)‎‎. ‎g‎overned by time-delay systems is investigated. ‎th‎is‎ thesis contains ‎tw‎o parts. ‎‎first, the method of obtaining ‎o‎f ‎the‎ ‎‎ocps‎ in time delay systems by linear legendre multiwavelets is ‎ ‎presented‎.‎‎‎‎ the main advantage of the meth...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه سیستان و بلوچستان 1390

seismic retrofit strategies have been developed in the past few decades following the introduction of new seismic provisions and the availability of advanced materials and methods. it can be observed that new approaches to deal with more lateral forces are more innovative and more energy absorbent. in line with this, there is a growing trend toward the use of steel shear walls as a system with ...

Replacement of the usual harvesting sugarcane method (burning field before harvesting) by green harvesting method could be the most important factor contributing to the ecological balance and stable sugarcane production in the Khuzestan region. To evaluate the green harvesting sugarcane method and its effects on the agronomic and physiological characteristics of sugarcane cultivars, a field exp...

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