With the continuous growth of data storage demand, precise and stable magnetic-head positioning in hard disk drives (HDDs) remains essential. This paper proposes a disturbance-rejection-oriented control design for triple-stage actuator (TSA) systems. The approach employs Bode-plot analysis to achieve robust performance against plant perturbations while explicitly incorporating the stroke limits of Lead Zirconate Titanate (PZT) micro-actuators into controller synthesis. Stroke constraints are represented as forbidden regions on the Bode diagram, providing an intuitive feasibility criterion for controller design. The physical stroke limitation is formulated as an inequality condition and embedded directly in the loop-shaping procedure. Performance is evaluated through hybrid simulations in which numerical plant models identified from measured actuator frequency responses are driven by disturbance signals generated from measured disturbance characteristics. The results demonstrate that the proposed controllers significantly reduce the risk of micro-actuator saturation while preserving high positioning accuracy.
With the rapid expansion of wind power generation, concerns have grown over bird collisions with turbines, particularly involving rare species such as the White-tailed Eagle (Haliaeetus albicilla). To evaluate potential impacts, we compared bird distribution estimates from roadside surveys with flight activity data from point censuses. Roadside surveys were conducted along a 110.4 km route over a one-year period, while point censuses were carried out at 33 sites—18 wind facilities and 15 control areas—to measure flight frequencies. Species distribution models were developed using MaxEnt, and their outputs were compared with point census results using generalized linear models. White-tailed Eagles showed the highest flight probability near coastlines, influenced by elevation and proximity to secondary forests. Slaty-backed Gulls (Larus schistisagus) were primarily associated with coastal proximity and artificial structures, with frequent flights in coastal and urban areas. Crows (Corvus spp.) exhibited high activity near fishing ports and livestock farms, reflecting their association with human structures. MaxEnt estimates of Slaty-backed Gulls and crows significantly predicted point census flight frequencies in GLM analysis. These results demonstrate that roadside surveys can efficiently and reliably estimate bird distributions in open landscapes with good visibility. Compared with point censuses, they offer a more cost-effective approach, making them a practical tool for environmental impact assessments and bird collision risk evaluations-especially in regions with limited resources.
HiZ-GUNDAM is a candidate for a Japan Aerospace Exploration Agency satellite mission expected to launch in the 2030s, aiming to detect high-redshift gamma-ray bursts (GRBs) and explore the early universe. The wide-field X-ray monitor EAGLE, onboard the HiZ-GUNDAM satellite and responsible for GRB detection and localization, employs lobster-eye-type micro-pore optics (MPOs) and a pnCCD as the focal-plane detector to focus soft X-rays in the 0.4 to 4.0 keV range. We established an alignment strategy for a modular lobster-eye MPO system, and the required alignment accuracy was derived through Monte Carlo simulations that reproduce the point spread function and localization performance. The optical characteristics of individual MPO segments were then evaluated to select and arrange four segments for a breadboard-level alignment demonstration. Subsequently, alignment tuning was performed by adjusting the angular positions of the MPO segments with actuators under X-ray irradiation in a vacuum environment, followed by an evaluation of the resulting direction-determination accuracy. The resulting angular response measurements show that the estimated incident angles derived from the focal positions achieve systematic uncertainties of less than 3 arcmin over more than 95% of the field of view. This level of performance satisfies the localization requirement for the EAGLE instrument when considering systematic errors intrinsic to the MPO-based detection system. These results demonstrate the feasibility of precise MPO alignment in a segmented lobster-eye optics system and provide practical feedback for the design, alignment strategy, and mechanical tolerance definition of future engineering and flight models of the EAGLE X-ray optics.
We report on the cosmic ray mass composition measured by the Telescope Array Low-energy Extension (TALE) hybrid detector. The TALE detector consists of a fluorescence detector (FD) station with 10 FD telescopes located at the Telescope Array (TA) Middle Drum FD Station (itself made up of 14 FD telescopes), and a surface detector (SD) array of scintillators. The array consists of 40 SDs with 400 m spacing and 40 SDs with 600 m spacing. In this paper, we present results on the measurement of the depth of shower maxima (Xmax) in the energy range from 1016.5 eV to 1018.5 eV collected over five years of the TALE hybrid detector. The Xmax distributions were analyzed and compared with Monte Carlo simulations of proton, helium, nitrogen, and iron primaries, using the QGSJet II-04 hadronic interaction model. Our results indicate that the elongation rate of the mean Xmax, which is defined as the slope of KXmaxi versus cosmic ray energy, exhibits a break around 1017 eV. Up to this energy, the composition becomes increasingly heavy, characterized by a growing dominance of heavy nuclei and a steadily decreasing fraction of light primaries. Beyond this energy, the proton fraction increases significantly with energy. These findings suggest a transition from Galactic to extra-Galactic cosmic ray sources around the so-called second knee.
An Al2O3/CeOx/SiO2/Si structure was fabricated using spin coating, and its memory mechanism was investigated. Counterclockwise hysteresis was revealed by capacitance-voltage (C-V) measurements. Measurements of the Ni/Al2O3/CeOx/SiO2/Si structure using high-energy X-ray photoelectron spectroscopy under an applied bias revealed that the binding energies of the Si 1 s and Al 1 s core levels shifted in the same direction. This indicates that this memory characteristic is attributable to charge trapping rather than interfacial dipole modulation. These findings contribute to the development of low-cost, solution-processed nonvolatile memory devices.
