11,396 research outputs found
Effective Fokker-Planck Equation for Birhythmic Modified van der Pol Oscillator
We present an explicit solution based on the phase-amplitude approximation of
the Fokker-Planck equation associated with the Langevin equation of the
birhythmic modified van der Pol system. The solution enables us to derive
probability distributions analytically as well as the activation energies
associated to switching between the coexisting different attractors that
characterize the birhythmic system. Comparing analytical and numerical results
we find good agreement when the frequencies of both attractors are equal, while
the predictions of the analytic estimates deteriorate when the two frequencies
depart. Under the effect of noise the two states that characterize the
birhythmic system can merge, inasmuch as the parameter plane of the birhythmic
solutions is found to shrink when the noise intensity increases. The solution
of the Fokker-Planck equation shows that in the birhythmic region, the two
attractors are characterized by very different probabilities of finding the
system in such a state. The probability becomes comparable only for a narrow
range of the control parameters, thus the two limit cycles have properties in
close analogy with the thermodynamic phases
Global stability analysis of birhythmicity in a self-sustained oscillator
We analyze global stability properties of birhythmicity in a self-sustained
system with random excitations. The model is a multi-limit cycles variation of
the van der Pol oscillatorintroduced to analyze enzymatic substrate reactions
in brain waves. We show that the two frequencies are strongly influenced by the
nonlinear coefficients and . With a random excitation, such as
a Gaussian white noise, the attractor's global stability is measured by the
mean escape time from one limit-cycle. An effective activation energy
barrier is obtained by the slope of the linear part of the variation of the
escape time versus the inverse noise-intensity 1/D. We find that the
trapping barriers of the two frequencies can be very different, thus leaving
the system on the same attractor for an overwhelming time. However, we also
find that the system is nearly symmetric in a narrow range of the parameters.Comment: 17 pages, 8 figures, to appear on Choas, 201
Diffusion Monte Carlo study of two-dimensional liquid He
The ground-state properties of two-dimensional liquid He at zero
temperature are studied by means of a quadratic diffusion Monte Carlo method.
As interatomic potential we use a revised version of the HFDHE2 Aziz potential
which is expected to give a better description of the interaction between
helium atoms. The equation of state is determined with great accuracy over a
wide range of densities in the liquid phase from the spinodal point up to the
freezing density. The spinodal decomposition density is estimated and other
properties of the liquid, such as radial distribution function, static form
factor, momentum distribution and density dependence of the condensate fraction
are all presented.Comment: 19 pages, RevTex 3.0, 7 figures available upon reques
Scattering length for helium atom-diatom collision
We present results on the scattering lengths of ^4He--^4He_2 and ^3He--^4He_2
collisions. We also study the consequence of varying the coupling constant of
the atom-atom interaction.Comment: Contribution to Proceedings of the International Workshop ``Critical
Stability of Few-Body Quantum Systems'' (Dresden, October 17--22, 2005
Reaksi Eterifikasi δ-Guaiene Menggunakan Katalis Fecl3/p-tsoh
Δ-guaien merupakan komponen utama kedua dari minyak nilam setelah patchouli alkohol yang dapat diderivatisasi menjadi senyawa eter dengan posisi pada karbon tersier. Senyawa eter pada posisi ini dapat digunakan sebagai zat campuran bahan bakar minyak untuk menaikkan angka oktan. Reaksi eterifikasi dapat dilakukan menggunakan berbagai macam reaksi dengan katalis logam. Penelitian ini fokus pada reaksi katalis logam untuk mensintesis senyawa eter dari δ-guaien sebagai bahan dasar. Reaksi dilakukan menggunakan katalis FeCl3/p-TsOH.H2O dan dianalisa menggunakan FTIR dan KG-SM. Hasil dari FTIR menunjukkan adanya puncak baru pada spectra IR pada 1076 cm-1 yang menunjukkan adanya ikatan C-O eter. Untuk hasil dengan KG-SM, diperoleh senyawa eter sebesar 1,25% dari kromatrogam KG-MS. Persen terbesar dari kromatrogam adalah senyawa alkohol sebesar 88,99%. Dari hasil tersebut dapat disimpulkan bahwa logam efektif digunakan sebagai katalis, namun untuk reaksi eterifikasi katalis seharusnya bebas dari kandungan air untuk mencegah terjadinya produk alkohol
Analisa Dampak Lalu-lintas Pengembangan RS Telogorejo Di Jl. K.h. Ahmad Dahlan Semarang
Telogorejo Hospital is a hospital located in the city center (CBD) with a lot of activity around it, so the traffic is congested. Currently, the private hospital is under developing with targeted towards an International hospital. Therefore it is important to assess the impact of traffic caused by the development. At the beginning of the calculation, we evaluated the performance of intersections and roads around the site development. Then proceed with the calculation of estimated towing vehicle movement and percentage growth. Both were included in the analysis of the performance of intersections and roads no hotspot at the post opening. The method of analysis used is MKJI (Indonesia Jalan Capacity Manual) 1997 dedicated to vehicle traffic. From the analysis it is known that the existing conditions in 2012 was the performance of intersections and roads hotspot is still good. It can be seen from the value of DS was still below 0.75, the speed on the road is still higher than 20 kilometer per-hour, and delay at the no hotspot intersection is still less than 30 seconds / smp. At the time of its unveiling in 2014, there is a condition on the Anggrek intersection at workingday at morning peak hours its DS value greater than 0.75 is 0.88. While the results of the analysis of the long-term 5 years after opening in 2019, Anggrek intersection performance became much worse that is the highest DS value of 1,04, but the intersection Theresiana still good. Technical solutions to address the intersection of Anggrek at the opening is to provide non-permanent median on the major approach of limiting the right turn movement on each approach and also a straight movement in South Seroja approach. The median was installed as weekday morning peak hour. In the segment of Road Anggrek is made diversion parking from the road. While the solution to the current problems five years after opening is to install a non-permanent median at the Anggrek intersection so there is no right turn movement on each approach and also the straight movement in South Seroja approach. It also made a major widening in line at 1 m on each side and minor lane widening at 0.5 m in each side. Simpang Theresiana good condition at present, at the opening, as well as five years after opening no problems whatsoever so there is no meaningful treatment. It's just that every Sunday morning there is a market there for people who can not be predicted future conditions, thus requiring further research
Social Welfare in One-Sided Matching Mechanisms
We study the Price of Anarchy of mechanisms for the well-known problem of
one-sided matching, or house allocation, with respect to the social welfare
objective. We consider both ordinal mechanisms, where agents submit preference
lists over the items, and cardinal mechanisms, where agents may submit
numerical values for the items being allocated. We present a general lower
bound of on the Price of Anarchy, which applies to all
mechanisms. We show that two well-known mechanisms, Probabilistic Serial, and
Random Priority, achieve a matching upper bound. We extend our lower bound to
the Price of Stability of a large class of mechanisms that satisfy a common
proportionality property, and show stronger bounds on the Price of Anarchy of
all deterministic mechanisms
High-quality variational wave functions for small 4He clusters
We report a variational calculation of ground state energies and radii for
4He_N droplets (3 \leq N \leq 40), using the atom-atom interaction HFD-B(HE).
The trial wave function has a simple structure, combining two- and three-body
correlation functions coming from a translationally invariant
configuration-interaction description, and Jastrow-type short-range
correlations. The calculated ground state energies differ by around 2% from the
diffusion Monte Carlo results.Comment: 5 pages, 1 ps figure, REVTeX, submitted to Phys. Rev.
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