نتایج جستجو برای: beta and gamma diversities using whitaker index
تعداد نتایج: 17401369 فیلتر نتایج به سال:
drought is transient phenomenon , slow , repetitive and integral part of the climate of each region. drought begins with a substantial reduction in precipitation over the long-term average rainfall and over time, reduced soil moisture and surface and ground water resources will continue to decrease. this phenomenon is the most important in bakhtegan basin because of its importance in strategic ...
abstract nowadays, industries cannot play a crucial role in national and international competitions. the tourism industry is no exception. tourism industry development as the most important economic sector and income generation is one of the key challenges of economic development in the world. therefore, countries were successful that take advantage of the capabilities of tourism sector using ...
Background: Natural radionuclides in rock samples, primarily 238U (uranium), 232Th (thorium) and 40K (potassium), are the main source of radiation exposure to workers and general public and their measurement is of paramount importance from radiation protection point of view. Materials and Methods: Gamma spectrometry using HPGe detector was used to measure the radioactivity and assess the radiol...
Our present study involves the strange stars model in framework of $f(R,T)$ theory gravitation. We have taken a linear function Ricci scalar $R$ and trace $T$ stress-energy tensor $T_{\mu \nu}$ for expression $f(R,T)$, i.e., $f(R,T)=R+ 2 \gamma T $ to obtain proposed model, where $\gamma$ is coupling constant. Moreover, solve hydrostatic equilibrium equations, we consider equation state between...
abstract: the present study was undertaken to investigate whether 1) there is any significant correlation between iranian efl/eap learners’ l2 writing proficiency and their willingness to communicate, 2) there is any significant difference between efl and eap learners in terms of willingness to communicate, 3) there is any significant difference in wtc of iranian efl/eap learners with 1- nati...
The Be stars display variable optical emission lines originating in the circumstellar disc. Here we analyse high resolution spectroscopic observations of and distance between peaks H-alpha, H-beta, H-gamma ($\Delta V_\alpha$, $\Delta V_\beta$, V_\gamma$ respectively). Combining published data, spectra from ELODIE archive (obtained period 1998 -- 2003) Rozhen 2015 2023) 93 stars, find a set rela...
any change in the refractive index of a laser active medium can lead to serious degradation of beam quality, laser beam modes, laser performance and variation in the intensity distribution. alteration in the refractive index of laser active medium is especially notable in high power lasers. it is clear that in the laser beam production, the pumping agent induces a great amount of heat which...
due to the limiting workspace of parallel manipulator and regarding to finding the trajectory planning of singularity free at workspace is difficult, so finding a best solution that can develop a technique to determine the singularity-free zones in the workspace of parallel manipulators is highly important. in this thesis a simple and new technique are presented to determine the maximal singula...
the world wide web becomes very popular recently and plays an influential role in english learning. by burgeoning role of source-based writing as partial fulfillment of tefl courses and vast use of the internet, lack of empirical studies to explore these areas is obvious. this study aimed to explore the effect of the amount of familiarity with the web (internet literacy) on junior english stude...
decomposability of an algebraic structure into the :union: of its sub-structures goes back to g. scorza's theorem of 1926 for groups. an analogue of this theorem for rings has been recently studied by a. lucchini in 2012. on the study of this problem for non-group semigroups, the first attempt is due to clifford's work of 1961 for the regular semigroups. since then, n.p. mukherjee in ...
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