A formula for calculating the rotational period of planet or star

This paper reports a formula for calculating the rotation period of planet or star. The rotational radius, the orbital velocity and the gravitational acceleration at its surface, the three factors, determine the rotational period of planet or star.

A formula for calculating the rotational period of planet or star

This paper reports a formula for calculating the rotation period of planet or star. The rotational radius, the orbital velocity and the gravitational acceleration at its surface, the three factors, determine the rotational period of planet or star.

New parameterizations of air-sea CO2 gas transfer velocity on wave breaking

<p>Ocean surface waves and wave breaking play a pivotal role in air-sea Carbon Dioxide (<em>CO<sub>2</sub></em>) gas exchange by producing abundant turbulence and bubbles. Contemporary gas transfer models are generally implemented with wind speed, rather than wave parameters, to quantify <em>CO<sub>2</sub></em> transfer velocity (<em>K<sub>CO2</sub></em>). In our work, the direct relationship of <em>K<sub>CO2</sub></em> and waves is explored through the combination of laboratory experiment, field observational data and estimation of global ocean uptake of <em>CO<sub>2</sub></em>.</p><p>In laboratory, the waves and <em>CO<sub>2 </sub></em>transfer at water surface are forced for simultaneous measurements in a wind-wave flume. Three types of waves are exercised: mechanically generated monochromatic waves, pure wind waves with 10-meter wind speed ranging from 4.5 <em>m/s</em> to 15.5 <em>m/s</em>, and the coupling of monochromatic waves with superimposed wind force. The results show that <em>K<sub>CO2 </sub></em>is well correlated with wave height and orbital velocity. In the connection of <em>K<sub>CO2 </sub></em>with breakers, wave breaking probability (<em>b<sub>T</sub></em>) should also be considered. The wind speed is competent too in describing <em>K<sub>CO2 </sub></em>but may be inadequate for varied wave ages. A non-dimensional formula (hereafter the RHM model) is proposed in which gas transfer velocity is expressed as a main function of wave Reynolds number (<em>R<sub>HM </sub>= U<sub>w</sub>H<sub>s</sub>/ν<sub>w</sub></em>, where <em>U<sub>w</sub></em> is wave orbital velocity, <em>H<sub>s</sub></em> is significant wave height, <em>ν<sub>w</sub></em> is viscosity of water) while wind is accounted as an enhancement factor (<em>1+Û</em>, where <em>Û </em>is non-dimensional wind speed denoting the reverse of wave age). For wave breaking dominated gas exchange, second formula (hereafter the BT model) is developed by replacing components of <em>R<sub>HM </sub></em>with breaker’s statistics and integrates an additional factor of <em>b<sub>T. </sub></em></p><p>Utilizing campaign observations from open ocean, the RHM model can effectively reconcile the laboratory and field data sets. The BT model related with wave breaking, on the other hand, is adapted by including a complementary term of bubble-mediated gas transfer in which the bubble injection rate is parameterized with <em>R<sub>HM</sub></em>. The updated BT model also performs well for the data. The conventional wind-based models show similar features as in laboratory experiments: the wind speed successfully captures the variation of gas transfer for respective observation yet is insufficient to neutralize the gaps among data sets.</p><p>Our wave-based gas transfer models are applied for the estimation of net annual <em>CO<sub>2</sub></em> fluxes of global ocean in the period of year 1985-2017. The results are in high agreement with previous studies. The wind-based gas transfer models might underestimate the <em>CO<sub>2</sub></em> fluxes although the estimations still distribute within the range of uncertainty. Moreover, the models using wave parameters are found advantageous over the wind-based models in reducing the uncertainties of gas fluxes.</p>

Sistem Kendali Penggerak Motor Stepper Pada Orbital Welding Menggunakan Perangkat Lunak LabVIEW

<p class="AbstractEnglish"><strong>Abstract:</strong> Orbital welding motion in welding for joining pipes or cylinders, has a circular or circular motion that includes horizontal or vertical motion. The orbital velocity for a welding gun is expected to have a steady and stable velocity. Therefore, the aim of this research is to design a control system to control the movement of a stepper motor in orbital welding using LabVIEW software and Arduino Mega 2560 hardware. , this system requires LabVIEW software and hardware in the form of an Arduino Mega 2560, and a TB6600 driver to control the movement of the actuator or stepper motor. The movement of the stepper motor in this welding is divided into 2 segments. Segment 1 moves from an angle of 0º-180º in a clockwise motion and segment 2 moves from an angle of 0º-180º in a counter clockwise motion. In this study, 10 variations of speed were used to determine the appropriate movement or speed for circular welding. This speed variation starts from a frequency of 1000-5500 Hz. From the RSME test that has been carried out, the results obtained with low error values at frequencies of 1000 Hz and 1500 Hz with error values of 0.325 and 0.175. Meanwhile, from the test of average speed or RPM, the results obtained successively from the frequency of 1000 Hz-5500 Hz, namely 3 rpm, 6 rpm, 6,024 rpm, 8.975 rpm, 9.897 rpm, 12.057 rpm, 15.09 rpm, 14.915 rpm, and 17.93 rpm.</p><p class="AbstrakIndonesia"><strong>Abstrak:</strong> Gerak pengelasan orbital pada pengelasan untuk penyambungan pipa atau silinder, mempunyai arah gerak mengitari atau melingkar yang mencakup gerak horizontal atau gerak vertikal. Kecepatan gerak orbital untuk sebuah welding gun diharapkan mempunyai kecepatan yang tetap dan stabil. Oleh karena itu, tujuan dari penelitian ini adalah membuat rancangbangun sistem kontrol pengendalian pergerakan motor stepper pada orbital welding menggunakan software LabVIEW dan hardware Arduino Mega 2560. Sebagai sumber tenaga gerak dari aktuator berupa motor stepper, agar dapat mengendalikan kecepatan dan arah sesuai dengan kebutuhan gerak dari motor, sistem ini membutuhkan perangkat lunak LabVIEW dan perangkat keras berupa Arduino Mega 2560, dan driver TB6600 untuk mengatur gerakan pada aktuator atau motor stepper. Pergerakan motor stepper dalam pengelasan ini terbagi menjadi 2 segment. Segment 1 bergerak dari sudut 0º-180º dengan pergerakan searah jarum jam dan segment 2 bergerak dari sudut 0º-180º dengan pergerakan berlawanan arah jarum jam. Pada penelitian ini dilakukan 10 variasi kecepatan yang berguna untuk menentukan pergerakan atau kecepatan yang sesuai untuk pengelasan melingkar. Variasi kecepatan ini dimulai dari frekuensi 1000-5500 Hz. Dari pengujian RSME yang telah dilakukan didapatkan hasil dengan nilai error yang rendah pada frekuensi 1000 Hz dan 1500 Hz dengan nilai error sebesar 0,325 dan 0,175. Sedangkan dari pengujian kecepatan atau RPM rata-rata didapatkan hasil secara berturut-turut dari frekuensi 1000 Hz-5500 Hz yaitu 3 rpm, 6 rpm, 6,024 rpm, 8,975 rpm, 9,897 rpm, 12,057 rpm, 15,09 rpm, 14,915 rpm, dan 17,93 rpm.</p>

Doppler profiles of the interacting contact binary W Corvi

ABSTRACT We use spectra from 2011 and 2012 to investigate the distribution of local effective temperature and non-orbital velocity over the surface of the common envelope of this peculiar contact binary. There seems to be a hot surface flow from the more massive to the less massive (secondary) component, possibly equatorial, which extends roughly one quarter-way around both sides of that secondary star, corresponding to the hotspot postulated to explain the star’s light-curve peculiarities. This feature is clear in the shape of the profiles of metallic lines, but it shows up in H α/H β profiles, as well. The profiles imply small flow velocities in contrast to those detected in some A-type W UMa systems, less than a few km s−1 for the primary but indeterminate for the secondary. We also classify the star’s spectrum (G1-2 V) and present more radial velocities confirming the Ruciński–Lu radial-velocity solution.

Statistical deprojection of intervelocities, interdistances, and masses in the Isolated Galaxy Pair Catalog

Aims. In order to study the internal dynamics of actual galaxy pairs, we need to derive the probability distribution function (PDF) of true 3D, orbital intervelocities and interdistances between pair members from their observed projected values along with the pair masses from Kepler’s third law. For this research, we used 13 114 pairs from the Isolated Galaxy Pair Catalog (IGPC). Methods. The algorithms of statistical deprojection previously elaborated were applied to these observational data. We derived the orbital velocity PDFs for the whole catalog and for several selected subsamples. The interdistance PDF is deprojected and compared to the analytical profiles expected from semi-theoretical arguments. Results. The PDF of deprojected pair orbital velocities is characterized by the existence of a main probability peak around ≈150 km s−1 for all subsamples of the IGPC as well as for the Uppsala Galaxy Pair Catalog. The interdistance PDFs of both the projected and deprojected data are described at large distances by the same power law with exponent ≈ − 2. The whole distributions, including their cores, are fairly fitted by King profiles. The mass deprojection yields a mass/luminosity ratio for the pairs of M/L = (30 ± 5) in solar units. Conclusions. The orbital velocity probability peak is observed at the same value, ≈150 km s−1, as the main exoplanet velocity peak, which points toward a possible universality of Keplerian structures, whatever the scale. The pair M/L ratio is just seven times the standard ratio for luminous matter, which does not require the existence of nonbaryonic dark matter in these systems.

Wave Orbital Velocity Effects on Radar Doppler Altimeter for Sea Monitoring

The orbital velocity of sea wave particles affects the value of sea surface parameters as measured by radar Doppler altimeters (also known as delay Doppler altimeter (DDA)). In DDA systems, the along-track resolution is attained by algorithms that take into account the Doppler shift induced by the component along the Earth/antenna direction of the satellite velocity, VS. Since the vertical component of the wave particle orbital velocity also induces an additional Doppler effect (in the following R-effect), an error arises on the positioning of the target on the sea surface. A numerical investigation shows that when the wavelength of sea waves is of the same order of magnitude of the altimeter resolution, the shape of the waveform might be significantly influenced by the R-effect. The phenomenon can be particularly important for the monitoring of long swells, such as those that often take place in the oceans.

Calculation of Winds Induced Bottom Wave Orbital Velocity Using the Empirical Mode Decomposition Method

Accurate bottom wave orbital velocity (BWOV) calculation is important for understanding critical dynamic processes (e.g., turbulent mixing, sediment transport) at the bottom boundary layer of the oceans. Here we first use the empirical mode decomposition (EMD) method to calculate BWOV and evaluate its performance by comparing with two conventional methods (spectra and velocity methods) using field measurements collected from an acoustic Doppler velocimeter (ADV). The results suggest that BWOVs calculated by the EMD method were well correlated (R2 ≥ 0.97) to the results by the other two methods but with a few percent discrepancies. Under strong wavy conditions, BWOVs from the EMD method were 8% and 6% smaller than those from the spectra and velocity methods, respectively. Under weak wavy conditions, BWOVs from the EMD method were 14% and 11% smaller than those from the spectra and velocity methods, respectively. Statistical distributions of BWOV suggest that the EMD method calculated instantaneous BWOVs and BWOV amplitudes closely matched the Gaussian and Rayleigh distributions, respectively. Uncertainty analysis suggests that the EMD method was capable of calculating the most accurate BWOVs among the three methods. While the spectra and velocity methods can provide robust BWOV estimation, they cannot completely avoid the errors caused by wave-unrelated motions and instrumental noise.