22,198 research outputs found
Coherent States for Generalized Laguerre Functions
We explicitly construct a Hamiltonian whose exact eigenfunctions are the
generalized Laguerre functions. Moreover, we present the related raising and
lowering operators. We investigate the corresponding coherent states by
adopting the Gazeau-Klauder approach, where resolution of unity and overlapping
properties are examined. Coherent states are found to be similar to those found
for a particle trapped in a P\"oschl-Teller potential of the trigonometric
type. Some comparisons with Barut-Girardello and Klauder-Perelomov methods are
noticed.Comment: 12 pages, clarifications and references added, misprints correcte
Spherically Symmetric Solutions in M\o ller's Tetrad Theory of Gravitation
The general solution of M\o ller's field equations in case of spherical
symmetry is derived. The previously obtained solutions are verified as special
cases of the general solution.Comment: LaTeX2e with AMS-LaTeX 1.2, 8 page
Evaluating Maintainability Prejudices with a Large-Scale Study of Open-Source Projects
Exaggeration or context changes can render maintainability experience into
prejudice. For example, JavaScript is often seen as least elegant language and
hence of lowest maintainability. Such prejudice should not guide decisions
without prior empirical validation. We formulated 10 hypotheses about
maintainability based on prejudices and test them in a large set of open-source
projects (6,897 GitHub repositories, 402 million lines, 5 programming
languages). We operationalize maintainability with five static analysis
metrics. We found that JavaScript code is not worse than other code, Java code
shows higher maintainability than C# code and C code has longer methods than
other code. The quality of interface documentation is better in Java code than
in other code. Code developed by teams is not of higher and large code bases
not of lower maintainability. Projects with high maintainability are not more
popular or more often forked. Overall, most hypotheses are not supported by
open-source data.Comment: 20 page
Solving multicollinearity problem of gross domestic product using ridge regression method
This study is dedicated to solving multicollinearity problem for the general linear model by using Ridge regression method. The basic formulation of this method and suggested forms for Ridge parameter is applied to the Gross Domestic Product data in Iraq. This data has normal distribution. The best linear regression model is obtained after solving multicollinearity problem with the suggesting of value
A Mechanistic Model on Catalyst Deactivation by Coke Formation in a CSTR Reactor
A mechanistic model on catalyst deactivation by coke formation in a continuous stirred tank reactor (CSTR) has been developed in the paper. Catalyst deactivation by coke formation was treated as a surface reaction. Four reaction mechanisms representing coke formation through different routes were proposed. The evolved system of ordinary differential equations (ODEs) was solved numerically using MATLAB. This approach was validated by applying it to the skeletal isomerization of 1-pentene over ferrierite. Simulation results were compared qualitatively to those
obtained from the literature. Simulation results indicated that coke formation is an extremely rapid process with fast formation of coke components on the strongest acid sites leading to final coke. The coke deposition is slower at higher residence times resulting in more stable product formation and weaker deactivation. The results obtained from this work revealed that the developed model is indeed able to successfully demonstrate the most essential features of catalyst deactivation by coke formation and are in agreement with the findings in the literature. Future work is aimed to extend the study to different reactors such as a plug flow reactor, in addition to analysis of the reaction system’s
sensitivity to variables such as temperature and pressure
The relationship between vapour pressure excess and air change rates in bedrooms : a pilot study
Air change rates can be measured using tracer gas techniques which can be costly and intrusive. Moisture data is more accessible, and there is a relationship between moisture conditions and ventilation. This study aims to investigate the relationship between vapour pressure excess and air change rates in bedrooms. The CO2 decay method was used to estimate air change rates when bedrooms were unoccupied in the morning. The relationship between the average hourly change in vapour pressure excess and the air change rate was examined. Results showed a very weak to no correlation between the variables possibly due to moisture buffering and airflow from other rooms
Analysis of DC Fault for Dual Active Bridge DC/DC Converter including Prototype Verification
Peer reviewedPostprin
- …