11,193 research outputs found
Four-week inhalation toxicity, mutagenicity and immunotoxicity studies of Keum-Yeon-Cho (NosmoQ), tobacco substitute composition, in mice
No full textSafety of Kcum-Yeon-Cho (NosmoQ), a tobacco substitute composition, was evaluated in terms of acute- and 4,weeks repeated-inhalation toxicity, mutagenicity, and immunotoxicity using Balb/e mice. The air inside the inhalation chamber was collected and analyzed by GC-MS. In acute inhalation toxicity test, male and female mice were exposed to 40 Keum-Yeon-Cho cigarettes, The 50% lethal concentration (LC50) of NosmoQ was considered to be much higher than 40 cigarettes in both sexes. In 4-week repeated inhalation toxicity test, male and female mice were exposed for 6 h/day, 5 days/week for 4 weeks to 10 and 20 cigarettes per day, while control mice ere exposed to Filtered air. Our data indicated that no observed adverse effect level (NOAEL) of Keuna-Yeon-Cho should be over 20 cigarettes per day. Results of Salmonella typhimarium reversion assay with/without histidine moiety, in vivo chromosomal aberration and in vivo micronucleus assays using mouse bone marrow cells revealed that Kcum-Yeon-Cho has 110 mutagenicity. Evaluation of peripheral cellular immunity of mice treated with Keum-yeong-Cho using in vitro lymphocyte proliferation assay showed no significant difference in mean stimulation index (SI) between mice exposed to Keum-Yeon-Cho and control mice. Mean CO concentrations and total particulate matter contents of 10 and 20 cigarettes were 21.1 +/- 1.23 and 40.7 +/- 1.21 ppm (mean +/-S.D.. it = 5). and 25.7+/-3.09 and 59.0+/-4.0 mg dry weight (mean +/-S.D., n = 5), respectively. Although at negligible concentration (less than ppb level) several polycyclic aromatic hydrocarbons (PAHs) were also detected, these results indicate that NosmoQ has no toxic effect on mice. (C) 2002 Elsevier Science B.V. All rights reserved.N
Novel Inter-Cell Interference Coordination Scheme Using Normalized Intended Energy Distribution Index with Low Computational Complexity
No full textArray Antenna with Suppressed Side Lobe Level for Millimeter-Wave Applications
No full textAs millimeter-wave(mm-wave) band is attracted for 5G. and autonomous driving technology, mm-wave band has become a commercial interest. In mm-wave radar applications, the suppression of the side lobe level has to he considered thoroughly. This paper proposes an array antenna structure that reduces the side lobe level by arranging the equal power divider in series from the uniform distribution structure. The beam patterns of the proposed 1x8 array antenna completely suppress the first side lobe. The level difference between a peak gain and side lobe level was 18.4dB. The proposed method provides an array antenna with low side lobe level for mm-wave radar applications such as motion sensing and security
Reconstruction of High-Frequency Lunar Digital Elevation Model using Shape from Shading
No full textThis paper deals with a procedure to reconstruct a lunar surface based on fusion of Shape from Shading with absolute depth information exploited from Lunar Orbiter Laser Altimeter data. The generation of accurate lunar digital elevation model which contains altitude and terrain shape of mission area is critical for lunar exploration mission design. The photoclinometric approach with Shape from Shading yields dense, high-frequency information while range scanning data from Lunar Orbiter Laser Altimeter complements the photoclinometric reconstruction with low-frequency, large scale reliable depth information. The proposed Shape from Shading algorithm utilizes the laser altimetry data as initial guess and iteratively calculates the high-frequency altitude information from high resolution image. The high-frequency depth variation caused by small crater and boulder is recovered by applying Shape from Shading
Time-to-go weighted optimal guidance with impact angle constraints
No full textIn this paper, the optimal guidance law with terminal constraints of miss distance and impact angle is presented for a constant speed missile against the stationary target. The proposed guidance law is obtained as the solution of a linear quadratic optimal control problem with the energy cost weighted by a power of the time-to-go. Systematic selection of guidance gains and trajectory shaping are possible by adjusting the exponent of the weighting function. A new time-to-go calculation method taking account of the trajectory curve is also proposed for implementation of the proposed law. Nonlinear and adjoint simulations are performed to investigate the performance of the proposed guidance law and time-to-go calculation method
Implementation of optimal guidance laws using predicted missile velocity profiles
No full textA class of weighted control-effort minimizing guidance laws are derived for missiles of varying velocity. As a practical weighting function, we consider a function of air density and missile velocity parameterized by positive real numbers. The resulting optimal guidance problem can be interpreted as the drag minimization problem for subsonic or supersonic missiles, depending on what parameters are used. This approach is extended easily to solve the drag minimization of a typical antiaircraft missile system with an arbitrary velocity profile and arbitrary drag characteristics, as demonstrated by a simulation study, We also present analytical results on how the guidance gain of the optimal law varies according to the values of the parameters. Because the optimal guidance laws make use of the future missile velocity profile, one critical issue is how to implement the laws. To avoid the difficulty that an inaccurately predicted missile velocity profile causes the guidance command to blow up in the last part of the engagement, we suggest two simple on-line velocity-profile updating schemes, which considerably alleviate the problem
Recursive time-to-go estimation for homing guidance missiles
No full textAddressed here Is the problem of computing accurate time-to-go estimates, which is an important issue in implementing various optimal guidance laws developed for missiles of time-varying velocity. A recursive time-to-go computation method which updates the time-to-go in a noniterative way Is presented. The recursive method includes an error compensation feature which explicitly computes the time-to-go error produced by non-zero initial heading errors. The proposed method is simple and straightforward to implement for any missile velocity profiles. Various numerical examples show that the proposed method works effectively for optimal guidance laws as wen as proportional navigation and augmented proportional navigation
Trajectory Optimization Using Cramér-Rao Lower Bound for Bearings-Only Target Tracking
No full textThe paper presents the optimal trajectory with minimum Cramér-Rao Lower Bound (CRLB) for 2D bearings-only target tracking problem. In the bearings-only target tracking problem, the position and velocity of the target is estimated only from the bearing angle information. The CRLB of the given estimation problem is derived. The optimal path is defined as a path that minimizes the weighted sum of CRLB diagonal entries. It is equivalent to the weighted sum of minimum estimation covariances. The optimal control problem is defined by employing UAV dynamic equations of motion. The UAV is assumed to perform subsequent coordinated turns for angle measurements. The optimal lateral acceleration of the UAV is calculated. The advantage of the optimal trajectory is demonstrated and compared through simulated examples. Maximum likelihood estimator is applied in the simulation
Electromagnetic Interference Reduction Method from Handheld Resonant Magnetic Field Charger (HH-RMFC) for Electric Vehicle
No full textPerformance characteristics of linear optimal guidance laws for varying velocity missiles
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