289 research outputs found
A Study on the Effects of Exception Usage in Open-Source C++ Systems
Exception handling (EH) is a feature common to many modern programming languages, including C++, Java, and Python, that allows error handling in client code to be performed in a way that is both systematic and largely detached from the implementation of the main functionality. However, C++ developers sometimes choose not to use EH, as they feel that its use increases complexity of the resulting code: new control flow paths are added to the code, "stack unwinding'' adds extra responsibilities for the developer to worry about, and EH arguably detracts from the modular design of the system. In this thesis, we perform an exploratory empirical study of the effects of exceptions usage in 2721 open source C++ systems taken from GitHub. We observed that the number of edges in an augmented call graph increases, on average, by 22% when edges for exception flow are added to a graph. Additionally, about 8 out of 9 functions that may propagate a throw from another function. These results suggest that, in practice, the use of C++ EH can add complexity to the design of the system that developers must strive to be aware of
Bose-Einstein condensation of finite number of confined particles
The partition function and specific heat of a system consisting of a finite
number of bosons confined in an external potential are calculated in canonical
ensemble. Using the grand partition function as the generating function of the
partition function, an iterative scheme is established for the calculation of
the partition function of system with an arbitrary number of particles. The
scheme is applied to finite number of bosons confined in isotropic and
anisotropic parabolic traps and in rigid boxes. The specific heat as a function
of temperature is studied in detail for different number of particles,
different degrees of anisotropy, and different spatial dimensions. The cusp in
the specific heat is taken as an indication of Bose-Einstein condensation
(BEC).It is found that the results corresponding to a large number of particles
are approached quite rapidly as the number of bosons in the system increases.
For large number of particles, results obtained within our iterative scheme are
consistent with those of the semiclassical theory of BEC in an external
potential based on the grand canonical treatment.Comment: 20 pages in RevTex with 4 Postscript figures. The e-mail addresses of
the authors are `[email protected]',and `[email protected]
The Specific Heat of a Trapped Fermi Gas: an Analytical Approach
We find an analytical expression for the specific heat of a Fermi gas in a
harmonic trap using a semi-classical approximation. Our approximation is valid
for kT>hw and in this range it is shown to be highly accurate. We comment on
the semi-classical approximation, presenting an explanation for this high
accuracy.Comment: To be published in Physics Letters A. 7 pages (RevTex) and 2 figures
(postscript
Density of states for Bose-Einstein condensation in harmonic oscillator potentials
We discuss how it is possible to obtain a reliable approximation for the
density of states for a system of particles in an anisotropic harmonic
oscillator potential. A direct application of the result to study Bose-Einstein
condensation of atomic gases in a potential trap can be given. In contrast to a
previous study, our method involves only analytic calculations.Comment: 7 pages, LaTeX2e, no figure
Tempe as Language: An Indonesian Village Revitalisation Mini-project
In Kandangan, a village in the Temmanggung Regency (Kabupaten Temanggung) in the Province of Central Java, tempe bunguk used to be a daily food—using locally grown bunguk beans—and made in many households. But imported blocks of tempe from China made with industrially grown soy beans have slowly crept in and replaced it. As part of her food skills mapping (a part of the Spedagi Project), Francisca Callista (Siska) went searching for what used to be eaten in her village, and for those who could remember how to make it
Bose-Einstein condensation under external conditions
We discuss the phenomenon of Bose-Einstein condensation under general
external conditions using connections between partition sums and the
heat-equation. Thermodynamical quantities like the critical temperature are
given in terms of the heat-kernel coefficients of the associated Schr\"odinger
equation. The general approach is applied to situations where the gas is
confined by arbitrary potentials or by boxes of arbitrary shape.Comment: 11 pages, LaTeX, to appear in Phys. Lett.
Investigations on finite ideal quantum gases
Recursion formulae of the N-particle partition function, the occupation
numbers and its fluctuations are given using the single-particle partition
function. Exact results are presented for fermions and bosons in a common
one-dimensional harmonic oscillator potential, for the three-dimensional
harmonic oscillator approximations are tested. Applications to excited nuclei
and Bose-Einstein condensation are discussed.Comment: 13 pages, 7 postscript figures, uses 'epsfig.sty'. Submitted to
Physica A. More information available at
http://obelix.physik.uni-osnabrueck.de/~schnack
Analysis and comparison of Scalextric, SCX, and Carrera Digital slot car systems: A mechatronic engineering design case study
Digital slot cars operate by transmitting both power and data over a single pair of wires much like DCC-controlled model railways and some home automation systems. In this manuscript we analyse and compare the cars, track, controllers, and electronic data transmission protocols of the three popular digital slot car systems
Ideal Fermi gases in harmonic oscillator potential traps
We study the thermodynamic properties of an ideal gas of fermions in a
harmonic oscillator confining potential. The analogy between this problem and
the de Haas-van Alphen effect is discussed and used to obtain analytical
results for the chemical potential and specific heat in the case of both
isotropic and anisotropic potentials. Step-like behaviour in the chemical
potential, first noted in numerical studies, is obtained analytically and shown
to result in an oscillatory behaviour of the specific heat when the particle
number is varied. The origin of these oscillations is that part of the
thermodynamic potential responsible for the de Haas-van Alphen-type effect. At
low temperatures we show analytically that there are significant deviations in
the specific heat from the expected linear temperature dependence, again as a
consequence of the de Haas-van Alphen part of the thermodynamic potential.
Results are given for one, two, and three spatial dimensions. In the
anisotropic case we show how the specific heat jumps as the ratio of oscillator
frequencies varies.Comment: 53 pages, 7 figure
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