Since 2007, close binary and multiple stars are observed by speckle interferometry at the 4.1 m Southern Astrophysical Research (SOAR) telescope. The HRCam instrument, observing strategy and ...planning, data processing and calibration methods, developed and improved during ten years, are presented here in a concise way. Thousands of binary stars were measured with diffraction-limited resolution (29 mas at 540 nm wavelength) and a high accuracy reaching 1 mas; 200 new pairs or subsystems were discovered. To date, HRCam has performed over 11,000 observations with a high efficiency (up to 300 stars per night). An overview of the main results delivered by this instrument is given.
One of the basic parameters in the use of thermoluminescent detectors is the angular characteristics, i.e. receiving different signals depending on the angle of radiation exposure. The TLD detector ...is typically installed in a slide/badge and here the angular characteristics may have an influence, adding non-uniform coverage of the detectors with filters for the correct determination of the dose as a function of energy, because the energy characteristics are usually not flat.
As part of the work, special MCP-N (LiF:Mg, Cu, P) detectors of various shapes were prepared to improve the angular characteristics. The detectors were round pellets with the same circular shape with a diameter of 4.5 mm, and a modified form inside (large and small drilled holes) or a modified surface (cavity or hemisphere). For comparison, standard MCP-N type detectors were used. Detectors in special boxes were exposed to X-rays with an energy of 80 keV. The radiation beam was formed by a medical X-ray apparatus adapted for experiments at the Warsaw University of Technology in Warsaw. Exposures were made for angles of 0, 30, 45, 50, and 90° for a dose of 1.5 mGy.
Results show that it is possible to improve the angular characteristics for detectors with modified shapes. Better angular characteristics will allow for more accurate measurements, in particular in comparison tests, for accreditation and other calibrations. Especially improved angular dependence detectors could be useful for H*(10) environmental measurements.
•Thermoluminescent detectors (TLD).•Angular dependence.•Environmental thermoluminescent detector.•Dose measurements.
Abstract In recent years, the layout of rotary instructing leaves in mutable loop worm wheels has been a research hotspot. The rotary instructing leaves are subjected to the action of hyperthermal ...and nippy airstream and the influence of frictional force on the spin axis. For the rotary instructing leaves, the combined action of hyperthermal and nippy airstream generates an aerodynamical moment, while frictional force generates a frictional moment. When the rotary instructing leaves rotate, the aerodynamical moment and frictional moment constantly change as the angular motion of the blades. This research is rare, and there is no mature case for reference. The article applies fluid-structure coupled heat transfer and software programming to seek the blade moment. During the process of blade angular motion from -10° to +10°, the total moment of the blade earlier rises and afterward falls. When the blade angular position is -2°, the total moment runs to vertex 3.74489 N·m. Test data from the exploration laboratory have validated this conclusion. The maximum deviation compared to the test data of the exploration laboratory is 4.562%. The aerodynamical and frictional moments are momentous indicators for mutable loop worm wheel study. They can offer physical references for the mutable loop design of a turbo. The paper can also offer a new method for the blade moment calculation. This is important sense for the innovation of mutable cyclic worm wheels.
Spintronics is a research field that aims to understand and control spins on the nanoscale and should enable next-generation data storage and manipulation. One technological and scientific key ...challenge is to stabilize small spin textures and to move them efficiently with high velocities. For a long time, research focused on ferromagnetic materials, but ferromagnets show fundamental limits for speed and size. Here, we circumvent these limits using compensated ferrimagnets. Using ferrimagnetic Pt/Gd
Co
/TaO
films with a sizeable Dzyaloshinskii-Moriya interaction, we realize a current-driven domain wall motion with a speed of 1.3 km s
near the angular momentum compensation temperature (T
) and room-temperature-stable skyrmions with minimum diameters close to 10 nm near the magnetic compensation temperature (T
). Both the size and dynamics of the ferrimagnet are in excellent agreement with a simplified effective ferromagnet theory. Our work shows that high-speed, high-density spintronics devices based on current-driven spin textures can be realized using materials in which T
and T
are close together.
We analyze the multipole excitation of atoms with twisted light, i.e, by a vortex light field that carries orbital angular momentum. A single trapped 40Ca+ ion serves as a localized and positioned ...probe of the exciting field. We drive the S 1 2 → D 5 2 transition and observe the relative strengths of different transitions, depending on the ion's transversal position with respect to the center of the vortex light field. On the other hand, transition amplitudes are calculated for a twisted light field in form of a Bessel beam, a Bessel-Gauss and a Laguerre-Gauss mode. Analyzing experimental obtained transition amplitudes we find agreement with the theoretical predictions at a level of better than 3%. Finally, we propose measurement schemes with two-ion crystals to enhance the sensing accuracy of vortex modes in future experiments.
Recent work has shown that irradiation with light possessing orbital angular momentum (OAM) and an associated phase singularity, that is an optical vortex, twists a variety of materials. These ...include silicon, azo‐polymer, and even liquid‐phase resins to form various helically structured materials. This article provides a review of the unique helical‐structured materials created and the novel fundamental phenomena enabled by this interaction between both the spin angular momentum and the OAM of light with matter. Such light‐induced helical‐structured materials will potentially lead to advanced photonic devices, for instance, metamaterials for ultrasensitive detection and reactions for chiral chemical composites.
Irradiation with light possessing orbital angular momentum and an associated phase singularity, that is an optical vortex, twists a variety of materials. Such light‐induced helical‐structured materials will potentially lead to advanced photonic devices, for instance, metamaterials for ultrasensitive detection and reactions for chiral chemical composites.
To achieve the high-precision angular velocity and angular acceleration estimation of spacecraft under high dynamic conditions, a novel method based on single-gimbal magnetically suspended control ...moment gyroscope (SGMSCMG) configuration is proposed in this paper. Both the angular rates and angular accelerations have been resolved analytically, and their comparative estimation precision between the proposed method and the traditional one has been further analyzed in the presence of gyro error and installation error. Compared to the traditional three-orthogonal configuration method, the proposed one employs any three SGMSCMGs in the control actuator configuration instead of additional rate gyros. All the inertial coupling items are retained tactfully in the angular rate and angular acceleration solution by the proposed method. Thus, the relative estimation accuracy of the attitude rate depends only on the gyro error and its installation error in practice, which do not decay under high dynamic conditions anymore. And its corresponding angular acceleration estimation precision is determined by the size of angular velocity instead of angular acceleration under the given error condition. The semiphysical simulation results demonstrate the correctness and superiority of the proposed estimation method.
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