Since the release of Android Nougat (N) version in 2016, Android smartphones have supported GNSS raw measurements. By using GNSS raw measurements, it is possible to calculate exact positions of the receiver through direct calculations. However, smartphones receive satellite signals through Planar Inverted-F Antennas (PIFA) due to their structural limitations. PIFA generally have weak signal reception performance. Furthermore, smartphones allocate limited processing resources to calculate satellite signals, resulting in frequent cycle slips for the carrier measurements of Android smartphones. Further, it is difficult to provide carrier measurement values for each smartphone manufacturer and to conduct Real-Time Kinematic (RTK) studies using carrier measurements from Android smartphones. In this study, we utilize Doppler measurements from Android smartphones to overcome these limitations. Although the quality of Doppler measurements is lower than that of carrier measurements, they are free from cycle slips and have a higher accuracy compared to the code measurements from Android smartphones. We propose that the position accuracy can be improved using a code-Doppler smoothing method that combines the Doppler measurements with code measurements. Additionally, we demonstrate that the accuracy can be enhanced by combining the code-Doppler smoothing method with the Differential Global Positioning System (DGPS) technique. To verify the proposed method, static and dynamic experiments were conducted. To compare the performances during the experiment, a NovAtel device was used as a high-performance receiver, and a Samsung device was used as a low-performance receiver.

We have been studying debris capture by shooting a metal harpoon into it. Potential harpoon tip shapes have been investigated, but their penetration behavior has not been studied in detail. Therefore, we employed numerical simulations to investigate penetration behavior. Friction between the harpoon and the target was found to have a significant influence on penetration behavior and the influence of this friction was especially strong when the harpoon was shot into the target at a large oblique angle. Friction suppresses slippage on the target surface, allowing the kinetic energy of the harpoon to be used for penetration, leading to a reduction in penetration velocity. The influence of tip shape on the penetration behavior was also investigated, revealing the deformation of the target in detail in stress distribution diagrams. When the tip shape of a harpoon was sharp (1-point contacting double-bladed or conical), and the harpoon hit the target at a point, a high-stress region was generated near the impact point, and a small fracture hole was created at the beginning phase of the penetration. After that, the harpoon tip is trapped in this fracture hole, suppressing slippage and improving penetration. Therefore, the effect of friction is reduced.

Well-executed strategic air traffic flow management (ATFM) such as ground delay programs and controlled enroute delays account for numerous uncertainties. Such initiatives aim to minimize unnecessary airborne and ground delays while maintaining sufficient arrival runway pressure. This can be achieved through setting a cap on the maximum allowable airborne delay, i.e. the GDP buffer. Previous studies have shown that the ideal buffer is influenced by anticipated traffic levels. This study examines the uncertainties in departure time predictions, such as those arising from delayed passengers, maintenance problems, or late aircraft arrivals, and explores their impact on buffer efficiency and potential losses due to inappropriate buffer selections. Cumulative ground delay, airborne delay and throughput loss (capacity loss) are used as metrics. A day of arrival traffic at a hub Japanese airport is modeled and the ATFM necessity is demonstrated. To investigate operational aspects such as predictability and air traffic control workload, the number of flights with airborne delay exceeding the buffer is evaluated for several departure time prediction uncertainty models. It is concluded that modeling departure time uncertainties is important for optimal buffer selection. These results also highlight the importance of actual operational data which will allow for such models to be developed.

This paper describes a method for predicting aircraft noise, auralization, and sound quality assessment by simulation in order to contribute to the study of future aircraft noise. A noise prediction tool was extended to reconstruct time-series sound data from acoustic spectra, and whether sound quality can be evaluated in the same way as measured sound data was investigated. The time series sound data was compared with the actual measured engine noise data, and it was found that there were no significant differences in perceived noise level (PNL), acoustic roughness, and sharpness. It was also found that there was a significant difference in sharpness between the side of the engine and the rear of the engine, although the PNL was the same level. In addition, the noise of future supersonic aircraft was generated using the prediction tool, and a case study was presented to allow the user to experience the noise and evaluate the sound quality. The results showed that differences in impressions that cannot be explicitly expressed by PNL can be made clear through the selection of psychoacoustic quantities.

Satellite-borne multi-aperture imagers are a promising optical system for high-resolution Earth observation. A significant challenge to realize such an imager is to develop an in-orbit fine phasing method to complete precise piston-tip-tilt alignment between sub-apertures to achieve diffraction-limited imaging performance. This study demonstrated the use of the simulated annealing algorithm for iterative scene-based fine phasing. One advantage of this approach is the correction capability of the piston-tip-tilt misalignment with a minimal hardware configuration. Numerical simulation revealed the relationship between fine phasing performance and the temperature parameters in the algorithm. Besides, algorithmic comparison with the stochastic parallel gradient descent algorithm, another approach capable of scene-based fine phasing, is also presented. Furthermore, we developed a miniaturized multi-aperture imaging system with 37 hexagonal mirror segments for our laboratory-scale optical experiments. The demonstration experiment showed the high-accuracy fine phasing results for typical extended scenes obtained by optical remote sensing.