1,492 research outputs found
파장 분할 다중화 링 네트워크의 자동 검색
No full textThe present invention relates to an automatic retrieval method of a wavelength-division multiplexed (WDM) ring network to the normal state after recovery of a failure. More specifically, the present invention relates to an automatic retrieval method of a WDM ring network to the normal state after recovery of a failure by inducing a lasing by making the gain of the closed loop larger than 1 using the fact that the recovered section in the ring network forms a closed loop immediately after the recovery of the failure
Optimal three-dimensional impact time guidance with seeker's field-of-view constraint
No full textThis paper proposes a new three-dimensional optimal guidance law for impact time control with seeker's Field-of-View (FOV) constraint to intercept a stationary target. The proposed guidance law is devised in conjunction with the concept of biased Proportional Navigation Guidance (PNG). The guidance law developed leverages a nonlinear function to ensure the boundedness of velocity lead angle to cater to the seeker's FOV limit. It is proven that the impact time error is nullified in a finite-time under the proposed method. Additionally, the optimality of the biased command is theoretically analyzed. Numerical simulations confirm the superiority of the proposed method and validate the analytic findings. © 2020 Chinese Society of Aeronautics and Astronautics
Minimum-effort waypoint-following guidance
No full textThis paper addresses the problem of minimum-effortwaypoint-following guidance with/without
arrival angle constraints of an Unmanned Aerial Vehicle. By utilizing a linearized kinematics
model, the proposed guidance laws are derived as the solutions of a linear quadratic optimal
control problem with an arbitrary number of terminal boundary constraints. Theoretical
analysis reveals that both optimal proportional navigation guidance and trajectory shaping
guidance are special cases of the proposed guidance laws. The key feature of the proposed
algorithms lies in their generic property. For this reason, the guidance laws developed can be
applied to general waypoint-following missions with an arbitrary number of waypoints and
an arbitrary number of arrival angle constraints. Nonlinear numerical simulations clearly
demonstrate the effectiveness of the proposed formulations
Energy-optimal waypoint-following guidance considering autopilot dynamics
No full textThis paper addresses the problem of energy-optimal waypoint-following guidance for an Unmanned Aerial Vehicle with the consideration of a general autopilot dynamics model. The proposed guidance law is derived as a solution of a linear quadratic optimal control problem in conjunction with a linearized kinematics model. The algorithm developed integrates path planning and following into a single step and is able to be applied to a general waypoint-following mission. Theoretical analysis reveals that previously suggested optimal point-to-point guidance laws are special cases of the proposed approach. Nonlinear numerical simulations clearly demonstrate the effectiveness of the proposed formulations
The Political Economy of Pre-industrial Trade in Northeast Asia
No full textThis paper examines why the countries of Northeast Asia (China, Korea, and Japan) in the early nineteenth century traded much less (as measured by the proportion of trade to GDP) than most countries in other parts of the world. It is argued that the most important reason for this are government policies that suppressed private trade. It is shown that these restrictive trade policies were designed to maximize the total net benefit from trade, covering not only economic net benefits but also non-economic benefits in the fields of diplomacy, defense, culture, and internal politics.trade policy, Northeast Asia, tribute system, private trade, maritime ban, geography, culture
Complete genome sequence of Clostridium botulinum type A strain (X58540) isolated from cattle feces
No full textABSTRACT The full genome sequence of Clostridium botulinum type A strain X58540 found in fecal samples from cattle exhibiting clinical symptoms of chronic botulism is presented here. The genome of X58540 consists of 2,371,631 bp with a GC content of 28.17% and is predicted to include 2,157 coding sequences
Guidance Scheme for Gun-Launched Gliding Guided Projectiles
No full textThis article presents a composite guidance approach tailored for gun-launched gliding-guided projectiles. The guidance scheme is designed to maximize the lift-to-drag ratio during the gliding flight phase, thereby extending flight range while adhering to impact angle constraints in the terminal homing phase to enhance warhead effectiveness. Given the inherent variability in initial glide conditions arising from operational characteristics, the proposed guidance strategy is designed to prioritize following optimal velocity rather than optimal glide path angle. For the terminal homing phase, the proposed approach integrates optimal impact angle guidance with an enhanced time-to-go and final velocity prediction method, taking into account aerodynamic drag and gravity effects. To facilitate a seamless transition in guidance, we propose a method for determining an appropriate switching point. Furthermore, we analyze the maximum achievable target range and impact angle within specified maneuvering limits. One of the key features of the proposed method is its formulation as a generalized guidance scheme aimed at maximizing flight range, offering advantages over existing methods. Moreover, despite its simplicity, the proposed approach achieves performance comparable to that of optimization results. Finally, we validate our findings through numerical simulations.
Pursuit-Based Long-Range Air-to-Air Missile Midcourse Guidance Robust to Changes in the Predicted Impact Point
No full textThis paper proposes a midcourse guidance method for long-range air-to-air missiles that is robust to changes in the predicted impact point (PIP) during flight. The guidance method consists of a reference trajectory with an altitude constraint and a pursuit-based guidance that follows the reference trajectory. Simulation comparisons with a suboptimal trajectory that maximizes terminal speed show that the proposed guidance method is significantly robust to changes in the PIP. The intercept performance for various peak altitudes and PIP change magnitudes is also analyzed
Review of data-driven computational guidance for unmanned aerospace vehicles
No full textThis paper explores the application of data-driven computational guidance in unmanned aerospace vehicles, emphasizing improving the optimality of guidance strategies through data-driven approaches. Unmanned aerospace vehicles are engineered to execute predetermined missions while adhering to a variety of physical and operational constraints. Both their design and operational strategies prioritize the efficient utilization of onboard resources. Data-driven methods can learn from data to develop well-trained neural networks that uncover underlying guidance patterns. These trained neural networks can rapidly generate optimal outputs in response to inputs with minimal computational cost. This characteristic of data-driven methods is particularly well-suited for guidance applications in scenarios with limited onboard computational resources. This paper reviews the state-of-the-art achievements in data-driven computational guidance. Simultaneously, we categorize these advancements based on the role of neural networks within the guidance system, referring to them as neural-end-to-end computational guidance and neural-assisted fixed-structure guidance, respectively. Additionally, the paper highlights several open problems and potential future research directions.
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