in this research, a semi empirical approach has been suggested for calculating the activation energyof unimolecular thermal decomposition of vinyl ethers yielding saturated products. the calculationprocedure is based on the use of molecular mechanics (mm) methods. these methods which involvethe construction of the transition state for a molecule mainly consider the formation of a “hydrogenbridg...

this paper reports the results of using three empirical methods (makkink, priestley-taylor and hargreaves) for estimating the reference evapotranspiration (et0) in the semi-arid region of tensift al haouz, marrakech (center of morocco). the penman-monteith equation, standardized by the food and agriculture organization (fao-pm), is used to evaluate the three empirical methods. the obtained et0 ...

conformations and electronic properties of a series of imidazobenzodiazepines are investigated by am1 semi-empirical quantum mechanics method. it is shown that substitution of cl in position 7 instead of 8, changes the geometry of the seven membered lactam ring; this may put the n5 nitrogen in a better positon to act as a hydrogen bond acceptor, and the phenyl ring in position 6 is probably mor...

An improved kinetic model for the Meinel bands of OH has been constructed from rate constants and Einstein A coefficients derived in recent laboratory experiments. Using a semiempirical parameterization of the state-to-state rate constants for OH(v) quenching by O2, the absolute OH(v) nightglow radiances are modeled to within the accuracies of the atmospheric constituent concentrations and the ...

The paper addresses the problem of autonomous underwater vehicle (AUV) modeling and parameter estimation as a means to predict the expected dynamic performance of underwater vehicles and thus provide solid guidelines during the design phase. The use of analytical and semi-empirical (ASE) methods to predict the hydrodynamic derivatives of the most popular class of AUVs is discussed. An applicati...

Two remote-sensing optical algorithms for the retrieval of the water quality components (WQCs) in the Albemarle-Pamlico Estuarine System (APES) were developed and validated for chlorophyll a (Chl). Both algorithms were semi-empirical because they incorporated some elements of optical processes in the atmosphere, water, and air/water interface. One incorporated a very simple atmospheric correcti...

Semi-empirical (AM1) electronic structure calculations are reported on a pH-switchable [2] rotaxane whose synthesis was reported in [Angew. Chem. Int. Ed., 36 (1997) 1904]. The [2] rotaxane possesses two cationic binding sites, with different affinities toward dibenzo [24] crown-8 (the ring component of the [2] rotaxane) depending upon the pH of the system. The computational results capture thi...

Semiempirical molecular orbital calculations have been performed for the first step in the alkaline hydrolysis of the neutral benzoylester of cocaine. Successes, failures, and limitations of these calculations are reviewed. A PM3 calculated transition state structure is compared with the PM3 calculated structure for the hapten used to induce catalytic antibodies for the hydrolysis of cocaine. I...

We have measured the transition process from the high to low resistivity states, i.e., the reset process of resistive switching based memristors based on Ni/HfO2/Sin+ structures, and have also developed an analytical model for their electrical characteristics. When the characteristic curves are plotted in the current-voltage (I-V) domain a high variability is observed. In spite of that, when th...

The electron-impact widths and shifts for six Eu ii lines and widths for three La ii, and six La iii multiplets have been calculated by using the modified semiempirical method. Estimation for Stark widths of 664.506 nm (Eu ii) and 666.634 nm (Eu iii) lines are given as well. The influence of the electron-impact mechanism on line shapes and equivalent widths in hot star atmospheres has been cons...