4,387 research outputs found
Postfledging Survival, Movements, and Dispersal of Ring Ouzels (Turdus torquatus)
We thank Invercauld Estate for cooperation with access to Glen Clunie. S. Redpath, J. Wilson, and S. Roos provided valuable comments on the manuscript. This study was funded by the Royal Society for the Protection of Birds, Scottish Natural Heritage, and the Cairngorms National Park Authority. J.L.L. was supported by the Natural Environment Research Council.Peer reviewedPublisher PD
Moments of spectral functions: Monte Carlo evaluation and verification
The subject of the present study is the Monte Carlo path-integral evaluation
of the moments of spectral functions. Such moments can be computed by formal
differentiation of certain estimating functionals that are
infinitely-differentiable against time whenever the potential function is
arbitrarily smooth. Here, I demonstrate that the numerical differentiation of
the estimating functionals can be more successfully implemented by means of
pseudospectral methods (e.g., exact differentiation of a Chebyshev polynomial
interpolant), which utilize information from the entire interval . The algorithmic detail that leads to robust numerical
approximations is the fact that the path integral action and not the actual
estimating functional are interpolated. Although the resulting approximation to
the estimating functional is non-linear, the derivatives can be computed from
it in a fast and stable way by contour integration in the complex plane, with
the help of the Cauchy integral formula (e.g., by Lyness' method). An
interesting aspect of the present development is that Hamburger's conditions
for a finite sequence of numbers to be a moment sequence provide the necessary
and sufficient criteria for the computed data to be compatible with the
existence of an inversion algorithm. Finally, the issue of appearance of the
sign problem in the computation of moments, albeit in a milder form than for
other quantities, is addressed.Comment: 13 pages, 2 figure
Pengaruh Ilustrasi Visual Meme “Rage Face” Terhadap Frekuensi Kunjungan Website 9gag
Dunia maya saat ini telah menjadi salah satu hiburan yang cukup populer di kalangan remaja dan pemuda. Kemudahan mengakses internet saat ini membuat pengguna internet semakin bertambah di berbagai belahan dunia, contohnya seperti bertambahnya jumlah pengunjung pada website 9GAG. 9GAG merupakan suatu website yang berisi gambar-gambar lucu yang menggunakan ilustrasi Rage Face. Ilustrasi Rage Face merupakan ilustrasi yang dianggap lucu oleh banyak orang dan sedang marak digunakan. Dengan demikian, Rage Face sebagai salah satu ilustrasi yang sedang marak digunakan di internet ikut berperan dalam frekuensi kunjungan terhadap suatu website. Teknik analisa yang digunakan dalam penelitian ini adalah kuantitatif yang digunakan untuk menguji hipotesa penulis, yaitu ilustrasi Rage Face berpengaruh pada frekuensi kunjungan pada website 9GAG. Hasil penelitian menunjukkan hipotesa penulis kurang tepat, karena Rage Face hanya berpengaruh pada kunjungan awal saja tetapi tidak pada kunjungan-kunjungan berikutnya
Reduced In-Plane, Low Frequency Helicopter Noise of an Active Flap Rotor
Results from a recent joint DARPA/Boeing/NASA/Army wind tunnel test demonstrated the ability to reduce in-plane, low frequency noise of the full-scale Boeing-SMART rotor using active flaps. Test data reported in this paper illustrated that acoustic energy in the first six blade-passing harmonics could be reduced by up to 6 decibels at a moderate airspeed, level flight condition corresponding to advance ratio of 0.30. Reduced noise levels were attributed to selective active flap schedules that modified in-plane blade airloads on the advancing side of the rotor, in a manner, which generated counteracting acoustic pulses that partially offset the negative pressure peaks associated with in-plane, steady thickness noise. These favorable reduced-noise operating states are a strong function of the active flap actuation amplitude, frequency and phase. The associated noise reductions resulted in reduced aural detection distance by up to 18%, but incurred significant vibratory load penalties due to increased hub shear forces. Small reductions in rotor lift-to-drag ratios, of no more than 3%, were also measure
Towards unified understanding of conductance of stretched monatomic contacts
When monatomic contacts are stretched, their conductance behaves in
qualitatively different ways depending on their constituent atomic elements.
Under a single assumption of resonance formation, we show that various
conductance behavior can be understood in a unified way in terms of the
response of the resonance to stretching. This analysis clarifies the crucial
roles played by the number of valence electrons, charge neutrality, and orbital
shapes.Comment: 2 figure
Delocalization and conductance quantization in one-dimensional systems
We investigate the delocalization and conductance quantization in finite
one-dimensional chains with only off-diagonal disorder coupled to leads. It is
shown that the appearence of delocalized states at the middle of the band under
correlated disorder is strongly dependent upon the even-odd parity of the
number of sites in the system. In samples with inversion symmetry the
conductance equals for odd samples, and is smaller for even parity.
This result suggests that this even-odd behaviour found previously in the
presence of electron correlations may be unrelated to charging effects in the
sample.Comment: submitted to PR
A Frequency-Reconfigurable Antenna With 1-mm Nonground Portion for Metal Frame and Full-Display Screen Handset Applications Using Mode Control Method
A frequency-reconfigurable antenna featuring four integrated switches for metal-frame and full-display screen handset applications is proposed in this paper. To achieve full-display aesthetics, the nonground portion of the proposed antenna is reduced to only 1 mm, making it impossible to formulate additional parasitic strips to enhance the bandwidth and radiation efficiency of the antenna. Four switches are employed in conjunction with the devised antenna to excite five resonant modes using the mode control method (MCM) to operate from 699 to 960 MHz and from 1710 to 2690 MHz. The proposed antenna is designed by employing several peripheral metallic components, such as steel sheet, USB, speaker box, and full-display screen into consideration, which enables the overall structure to be much closer to a practical smartphone environment. A prototype was fabricated and measured. The experimental results confirm that the proposed antenna features radiation efficiency from 30% to 55% for metal-frame and full-display screen handset applications.11Ysciescopu
Performance of nano-structured multilayer PVD coating TiAlN/VN in dry high speed milling of aerospace aluminium 7010-T7651
A low-friction and wear resistant TiAlN/VN multilayer coating with TiAlN/VN bilayer thickness 3 nm has been grown by using the combined cathodic arc etching and unbalanced magnetron sputtering deposition on high speed steel tools for dry cutting of aluminium alloys. In this paper, in-lab and industrial high speed milling tests have been performed on an aerospace aluminium alloy 7010-T7651. The results show that the TiAlN/VN coated tools achieved lower cutting forces, lower metal surface roughness, and significantly longer tool lifetime by three times over the uncoated tools as a result of the low friction and eliminated tool-metal adhesion. Under the same conditions, a TiAlN based multicomponent coating TiAlCrYN also increased the tool lifetime by up to 100% despite the high cutting forces measured
- …