A new interpretation of the historical records of observing Venus in daytime with naked eye: Focusing on the meteorological factors in the astronomical observation records

Observing Venus during the daytime is challenging. However, observational data of Venus during the daytime can be found in history books from East Asian countries such as Korea, China and Japan. In this study, we are focused on data from Korean history book, and using records left in the Joseon wangjo sillok, one of the Korean history books from the Joseon dynasty (CE 1392–1910), tries to prove whether the reported observations were actual observation data. We collected these 4663 records from the Joseon wangjo sillok to determine whether they were actual observations, and to confirm the scientific validity of the records. When we looked at the distribution of observations on a yearly basis, we noticed that there were more observations in the fall and winter, while there were only limited numbers of observations in the spring. This difference in distribution suggests that observations were strongly affected by atmospheric conditions due to the weather. From the 4663 data collected, we found a cycle of about 1.6?years. The cycle of about 1.6?years is assumed to be related to the conjunction cycle of Venus. And, we found a cycle of about 1.0?years. The cycle of about 1.0?years is assumed to reflect the indirect effects of the Asian dust phenomenon. Our research result verified the record as actual observational data. In addition, this result verified that meteorological factors were involved in the recorded astronomical observation data. We think that our data can be helpful to climate studies on the natural sources of key climate-affecting aerosols.     

Wave resistance defect in a planar flow over periodic reliefs

The dependence of the wave resistance coefficients for planar periodic reliefs on the similarity parameters is investigated. It is proved that the wave resistance coefficients of the infinite reliefs and their finite analogs in the case of the whole wave numbers coincide, whereas in the case of the fractional wave numbers they differ.     

Wave resistance of rough plane channel walls in the supersonic flow

We propose a method that makes it possible to obtain in the framework of linear approximation the exact formulas for the wave resistance of the channel walls with an arbitrary plane pattern in the first and subsequent interference zones. It is shown by a particular example of the sinusoidal pattern that the pressure wave interference may lead to the positive or negative resistance resonance.     

Report on the Kiso cometary dust trail survey

Cometary dust trails were first observed by IRAS; they are widely known to be the origins of meteoric showers. A new window has been opened for the study of dust trails, using ground-based observations. We succeeded in obtaining direct images of the 22P/Kopff dust trail with the Kiso 1.05-m Schmidt telescope. Following this initial success, we have continued to perform a dust trail survey at Kiso. As a result of this survey, we have detected dust trails along the orbit of six periodic comets, between February 2002 and March 2004. The optical depth of these dust trails are 10⁻⁹ to 10⁻⁸, which is consistent with IRAS measurements. In this paper, we describe the observations and data reduction procedures, and report the brief result obtained between February 2002 and March 2004.     

Optimal FIR filters for time-varying state-space models

An optimal FIR (finite impulse response) filter and smoother is introduced for the time-varying state-space model. The suggested filter has an FIR structure and utilizes finite observation. It is shown that the impulse response of the optimal FIR filter can be obtained by a simple Riccati-type matrix differential equation. Especially for time-invariant systems, this FIR filter reduces to previously known simple forms. For implementation, a recursive form of the optimal FIR filter and smoother is derived by using adjoint variables, and computational algorithms are suggested. It is also shown by sensitivity analysis that the proposed optimal FIR filter alleviates potential divergence characteristics of the standard Kalman filter     

VLSI architecture for SAR data compression

As a step towards a real-time signal aperture radar (SAR) correlator, custom very large scale integration (VLSI) architectures are developed. Considering the extremely short word length of the data, we derive three architectures with massive parallelism in bit space. Unlike frequency methods, no. degradation is introduced during convolution. Optimized for time and space, they are highly suited to VLSI implementation, and a small architecture with 80 taps operating at 10 MHz has been built using an FPGA     

Experimental research of wave resistance resonance for rough-wall plane channels

We experimentally confirmed the effect when the wave resistance of rough-wall plane channels, generated while the walls are streamlined by a supersonic gas flow, reaches the extreme values. The experiments were conducted on a differential setup by comparing the tests of flat and round sonic nozzles. The results of the experiment justified the developed method of calculating the wave resistance of the plane channel with sawtooth wall relief.     

Object-based SAR image compression using vector quantization

A simple and elegant algorithm is presented to encode images with rich content, which allows easy access to various objects. An object-plane-based encoding method for compression of synthetic aperture radar (SAR) imagery is developed, with different object planes for target classes and background. A variable-rate residual vector quantization (VQ) algorithm is developed to encode the background information. This algorithm is very powerful as indicated by the experimental results. The proposed coding scheme allows compression matched to the final application of the images, which in this case is target recognition and classification.     

Changes to vascular biometric system security & performance

When considering biometrics for a Personal Identification System, different modalities can be considered. The final selection will depend on specific application requirements. From the several modalities existing nowadays, vascular systems have appeared on the scene lately. Vein-based identification is claimed to be as reliable as fingerprint or iris identification, but with the usability of hand geometry or even the face. As with any other biometric modalities, vascular solutions have to be deeply analyzed for all relevant factors that could affect their performance or the security level achieved. This will show the analysis of the performance and security achieved by a commercial vascular biometric system, when being applied in several real-world scenarios. These scenarios will cover typical office environments to the more extreme environments, such as extreme light and temperatures, as those suffered in a banking ATM, or with high humidity such as in a gym. The results will show the strengths of this modality, as well as those points where further improvements are needed.     

Pointing control of spacecraft using two SGCMGs via LPV control theory

In this paper, we consider a pointing control of a spacecraft using two single-gimbal control moment gyros (SGCMGs). Our pointing control problem is to make the line-of-sight of a camera or an antenna that is fixed on a body axis aim along a desired direction. To solve this problem, we first state the control objective for the pointing control through the angular momentum conservation principle. Then, we develop a gain-scheduled (GS) controller via linear parameter-varying (LPV) control theory. Finally, the feasibility of the proposed control method is shown by a numerical simulation.