Launch Positions Research Articles

Improving time and energy efficiency in multi-UAV coverage operations by optimizing the UAVs’ initial positions

This paper focuses on Coverage Path Planning (CPP) methodologies, particularly in the context of multi-robot missions, to efficiently cover user-defined Regions of Interest (ROIs) using groups of UAVs, while emphasizing on the reduction of energy consumption and mission duration. Optimizing the efficiency of multi-robot CPP missions involves addressing critical factors such as path length, the number of turns, re-visitations, and launch positions. Achieving these goals, particularly in complex and concave ROIs with No-Go Zones, is a challenging task. This work introduces a novel approach to address these challenges, emphasizing the selection of launch points for UAVs. By optimizing launch points, the mission’s energy and time efficiency are significantly enhanced, leading to more efficient coverage of the selected ROIs. To further support our research and foster further exploration on this topic, we provide the open-source implementation of our algorithm and our evaluation mechanisms.

С этой ракеты начинался наш путь в «Тополиную рощу» (о проведении летных испытаний межконтинентальной баллистической ракеты РТ-2 на полигоне «Плесецк»)

In the first half of the 1960s, Special Design Bureau No. 1 created the RT-2 intercontinental ballistic missile. The use of the new missile in the Strategic Missile Forces was supposed to be part of the Separate Start type missile system. It was meant to be a worthy response to the American Minutemen. For the RT-2 rocket flight development tests, an experimental test base (technical and launch positions, command-measuring and computing complexes) and infrastructure facilities (roads, bridges) were created, fall fields and target fields were prepared, testing military units were formed, and personnel was trained. In 1966-68, flight tests of the RT-2 rocket were carried out as part of the 15P098 missile system. Although the RT-2 missile did not match the American Minutemen in terms of shooting accuracy and throw-weight, it was put into service and its modified version was on combat duty until 1994. The RT-2 became the first domestic solid-fuel intercontinental ballistic missile. An original layout and a new control system allowed it to “almost catch up” with the characteristics of Minuteman-2 and created the prerequisites for its further modernization. An excellent silo launcher, the best command post at that time, the first remote control and monitoring systems, and a small number of maintenance personnel made the system with these missiles one of the best in the Strategic Missile Forces at the beginning of the 1970s. The purpose of this article is to summarize information about the flight development tests of the RT-2 missile at the 53rd Research Test Site of the USSR Ministry of Defense (Mirny, Arkhangelsk Region). To achieve it, in addition to official documents and technical documentation, the author used information from the archives of testing military units and memories of participants in the events.

Random Error Analysis of Launch and Injection Positions for Distributed Multi Micro-nano Satellite System

Accurate satellite orbit calculation has always been a focus in the aerospace field. Especially, the error distribution of the orbit involving various internal and external factors in the satellite launch process has an important influence on the effectiveness of the satellite cluster. To qualitatively and quantitatively analyze the cooperative efficiency of multi-satellite clusters involving various random errors, this paper analyzes the random error sources in the launch process of micro-nano satellites and studies the distribution law of these satellite orbit position errors. Based on the parameter estimation and the central limit theorem of probability theory, the expression of the error function for the satellite’s orbit position is also constructed. In addition, the probability distribution model of the satellites in a certain range is designed, and the relationship between the number of satellites and the overall errors is proposed. Finally, the result is verified by the simulation experiment, which provides the rationale behind the position and altitude adjustment and constellation optimization of micro-nano satellites.

Node topology location method of SDN social network based on ant colony algorithm

Due to the convergence defect of the existing SDN social network node topology location methods, there is a large node topology location error problem. In order to solve the above problems, this paper proposes a topology location method of SDN social network nodes based on ant colony algorithm. Firstly, the ant colony algorithm is introduced, and then the biological principle of ant colony algorithm is analyzed to determine the basic steps of ant colony algorithm. According to the number of mobile beacon launch positions and specific launch coordinates in ROI, ant colony algorithm is introduced into the mobile beacon path acquisition program to realize SDN node topology location based on ant colony algorithm. The experimental results show that under the background of node communication radius of 2.0 and 5.0, the node topology positioning errors of this method are small, and the minimum errors are 9.10% and 5.15% respectively. It is fully proved that this method has good node topology positioning effect.

Return-sweep saccades in oral reading

Recent research on return-sweep saccades has improved our understanding of eye movements when reading paragraphs. However, these saccades, which take our gaze from the end of one line to the start of the next line, have been studied only within the context of silent reading. Articulatory demands and the coordination of the eye–voice span (EVS) at line boundaries suggest that the execution of this saccade may be different in oral reading. We compared launch and landing positions of return-sweeps, corrective saccade probability and fixations adjacent to return-sweeps in skilled adult readers while reading paragraphs aloud and silently. Compared to silent reading, return-sweeps were launched from closer to the end of the line and landed closer to the start of the next line when reading aloud. The probability of making a corrective saccade was higher for oral reading than silent reading. These indicate that oral reading may compel readers to rely more on foveal processing at the expense of parafoveal processing. We found an interaction between reading modality and fixation type on fixation durations. The reading modality effect (i.e., increased fixation durations in oral compared to silent reading) was greater for accurate line-initial fixations and marginally greater for line-final fixations compared to intra-line fixations. This suggests that readers may use the fixations adjacent to return-sweeps as natural pause locations to modulate the EVS.

A Simulation of the Effects of Badminton Serve Release Height

In this work, we develop and calibrate a model to represent the trajectory of a badminton shuttlecock and use it to investigate the influence of serve height in view of a new serve rule instated by the Badminton World Federation. The new rule means that all players must launch the shuttlecock below a height of 1.15 m, as opposed to the old rule whereby the required launch height was under the rib cage of the server. The model is based on a forward dynamics model of ballistic trajectory with drag, and it is calibrated with experimental data. The experiments also served to determine the actual influence of the new rule on the shuttlecock launch position. The model is used in a Monte Carlo simulation to determine the statistical influence of the new serve rules on the player’s ability to perform good serves; i.e., serves with little opportunity for the receiver to attack. We conclude that, for the female player in question, serving below a height of 1.15 m makes it marginally more difficult to perform excellent serves. We also conclude that there might be alternative launch positions that would be less likely to produce the best serves but could be exploited as a tactical option.

A Method for Coupling Monte Carlo Simulations of Photon Transport to Focused Gaussian Beam Propagation

We present a method for modeling focused Gaussian beams in turbid media. Compared to previous methods based on ray tracing, our method is simple and fast. Rather than sampling photon launch positions from the surface of the media, we directly sample launch positions from inside the sample volume using the probability distribution for the position that a ballistic photon will first interact with the tissue. The examples presented illustrate the importance of accounting for Gaussian beam optics when simulating a focused beam. Not doing so will give an artificially large irradiance at the beam waist position. Thermal models used to predict laser damage to tissue will predict temperature rises that are too large for samples containing the beam focus.

Hydrodynamic-Interaction Analysis of an Autonomous Underwater Hovering Vehicle and Ship with Wave Effects

A new vertical axis-symmetrical dish-shaped autonomous underwater vehicle (AUV) with excellent maneuverability, known as the autonomous underwater hovering vehicle (AUH), is proposed. This study investigates an important working model of the AUH approaching a host ship in waves. The working model of AUH–Ship interactions deals with hydrodynamic interaction, seakeeping performance for communication, launch, and recovery near a free surface. The AUH is able to navigate and implement homing automation through acoustic positioning equipment, a depth sensor, a heading compass, and a Doppler velocity log (DVL) in the working area based on numerical analysis of AUH–Ship hydrodynamic performance in this study. The hydrodynamic-interaction performance of the AUH and ship near free surfaces is analyzed in the frequency and time domains using a potential-based surface-panel method based on a commercial computational fluid dynamics (CFD) solver (ANSYS-AQWA), i.e., a 3D panel code of seakeeping performance module in the ANSYS platform where the fluid is assumed to be irrotational, inviscid, and incompressible. The motion performance of the AUH approaching the host ship, with a dynamic positioning system in waves, is studied by estimating interactive response-amplitude operators (RAOs) of the AUH and host ship in 6-DOF that were estimated and analyzed at different wave amplitudes and frequencies. In the ship and AUH interaction simulations, the host ship is assumed to be a well-posed station keeping in waves with zero service speed. The AUH and ship interference effect is studied at different distances to appropriate recovery and launch positions for the AUH at the following sea and beam sea, i.e., wave-encounter angles 0° and 90°, respectively. In addition, the hydrodynamic interaction of the AUH and ship in yaw and roll at different AUH velocities is estimated. The AUH motion performance approaching the ship in long-crested irregular seas is analyzed in the time domain using the Pierson–Moskowitz wave spectrum model. Viscid hydrodynamic force on AUH motion in roll near a free surface was significant. A damping model was adopted to formulate the viscid effect to enhance the effectiveness of the ANSYS-AQWA inviscid potential-based solver. Numerical analysis of motion RAO of the AUH in roll with the damping effect was compared to the experimental data in wave-frequency range 0.2–1.0 Hz, resulting in the average error being reduced from 21.03% to 9.95% to verify the method’s accuracy. The proposed method conveniently and accurately predicted hydrodynamic-interaction characteristics and motion RAO for a dish-type AUH and host ship for the precise use of mounted sensors in waves. The results of these simulations can be used to analyze the homing automation and adaptive controllability to advance the AUV development and design.

PRACTICAL APPROBATION OF THE DEVELOPED MEASURES ON ECOLOGICAL-HYGIENIC AND TOXICOLOGICAL ESTIMATION OF THE ENVIRONMENT IN THE DISTRICT OF THE FORMER OBJECTS OF THE MINISTRY OF DEFENSE

The evaluation of the sanitary-hygienic and ecological state of the environment on the territory of the location of the former silo launchers of intercontinental ballistic missiles after their partial elimination, as practical testing of the main provisions of the developed draft methodological manual on ensuring of environmental and hygienic safety of the sites for placing silo launchers after their decommissioning and Land reclamation. A comprehensive observation of the combat launch positions of liquid intercontinental ballistic silo based missiles after their decommissioning and partial liquidation was carried out. In accredited testing laboratories in soil, water, building structures, there were carried out.studies of the qualitative and quantitative content of unsymmetrical dimethylhydrazine (UDMH) and its degradation products, heavy metals, radionuclides. In studied soil samples unsymmetrical dimethylhydrazine was found to be in the soil in 69.4.7% of cases, and in 40.8% of cases in the studied samples, the excess of the MPC content of UDMH was recorded by 1.2 - 32 times. The study of soil on the degradation products of UDMG revealed their presence in some substances in most of studied samples, but their values did not exceed the MPC. The content of a number of heavy metals, both anthropogenic (zinc, lead, nickel) and natural (cobalt, chromium) nature was noted to exceed the maximum permissible and approximately permissible concentrations. It has been established that if the incomplete disposal of the former chemically hazardous facilities of the Ministry of Defense and land reclamation is concerned, the environment may contain toxic and highly toxic substances in concentrations exceeding the established standards. This circumstance determines the potential danger of decommissioned, but not properly disposed former military facilities for the environment, as well as for the local population. The experience gained during the practical activities made it possible to make the necessary additions and changes to the final version of the draft document on ensuring environmental and hygienic safety of the areas where the silo launchers were placed after their decommissioning and land reclamation.

Numerical Modelling of the Ice Throw from Wind Turbines

Ice throw is a significant risk factor in the vicinity of wind turbines located in cold climate areas. We present a method to estimate the ice chunk trajectories. First, similar to the common practice, only translation is accounted for and the object trajectory is determined by gravity and the aerodynamic drag force. The sensitivity of the trajectories to the launch positions, wind speed, turbine rotation and aerodynamic drag is assessed. Next, trajectory computations with six-degree-of-freedom motion are presented. The required aerodynamic forces and moments are precomputed using CFD. The results indicate that object rotation might be non-negligible when higher accuracy is needed for the trajectory estimates.

Surface Brillouin Scattering in Disordered Optical Fibers With Transverse Anderson Localization Guiding Mechanism for Evaluation of Longitudinal Structural Fluctuations

We numerically investigate the surface Brillouin scattering (surface-BS) in a transverse Anderson localization (TAL) guiding silica glass-air disordered optical fiber (DOF) with random air-holes. The normalized light intensity profiles of light beams propagating along DOF at different launch positions are obtained, which confirms the TAL mechanism. Then, the surface-BS in DOF is numerically investigated by the equation of elastodynamics with the electrostriction. It is found that there are two main peaks in the surface-BS spectrum and the Brillouin frequency shift (BFS) is sensitive to the air-fill fraction of DOF. Furthermore, the feasibility of longitudinal structural fluctuations evaluating of DOF by the Brillouin optical time-domain analysis technique is analyzed and discussed. The average sensitivity of BFS to the air-fill fraction is simulated to obtain an optimal performance in practical application. This paper is an interesting theoretical enlightenment for combining the novel concepts of surface-BS and DOF, also a useful exploration of longitudinal structural evaluating method for special optical fibers with microstructures.

Analysis of efficiency of deck diverce masking from distribution-diversion glaiders by a formable embody buffer zone

The object of research is the process of elastic interaction of an ultrasonic beam with a cylindrical module enclosing the airplane in the form of two circular shells of the same length coaxially connected by their ends, the hermetical gap between them filled with liquid. One of the problematic areas of the study is that the dislocation of deck aviation in the open waist plane allows the means of detecting the suborbital and atmospheric reconnaissance of the enemy to determine undefined not only the initial coordinates but also its coordinate functions for the entire period of subsequent trajectory travel. Finally, the on-board glider equipment, taking this information as the original one, makes it possible, with anticipation, accurately, to fire at the theoretical trajectory of motion, thereby increasing the probability of hitting the target. Therefore, it is necessary to ensure 100 % masking of deck aviation at open launch positions. This will significantly reduce or completely eliminate and improve the efficiency and life-span of the aircraft as a whole. It is shown that, when the case is subjected to symmetrical oscillations, which greatly exceed the resistance to antisymmetric vibrations, the sound permeability of the case elements will increase solely by bending vibrations. It is revealed that the «acoustic transparency» of the device case serves as an intensive transfer of the sound energy of the bending waves of the case and completely depends on the frequency of the acoustic radiation, as well as the incidence angles. Thus, by creating a circular or ellipsoidal enclosing cylindrical module in the form of two circular shells filled with liquid, it will be possible to quickly disassemble and place it over another object in a matter of hours.

J2010203 放物運動の最適角 : 初等力学と最適化問題

The derivation of the maximum projection angle in projectile motion of a particle gives one of the most popular examples in elementary mechanics. This procedure is also a typical example of optimization problem although it has not been emphasized in many textbooks of mechanics. We formulate the problem on the basis of the optimization approach, and obtain the perturbed solution in terms of aerodynamic parameters. This solution yields the optimum angles in the following three examples: simple projection with vertical displacement between launch and landing positions, projection with initial speed depending on initial angle and also projection under the action of fluid dynamic forces such as drag and lift proportional to flight speed. These results show realistic angles in several projection phenomena appearing in our usual life, and successfully explain the mechanism. This fact means the significance of optimization approach in elementary mechanics, and it will be effective to introduce this concept to early education in mechanics.

Bidirectional grating coupler based optical modulator for low-loss Integration and low-cost fiber packaging

We proposed and demonstrated a novel optical modulator based on a bidirectional grating coupler designed for perfectly vertical fiber coupling. The grating functions as the fiber coupler and 3-dB splitter. To observe the interference, an arm difference of 30μm is introduced. As a result of the high coupling efficiency and near perfect split ratio of the grating coupler, this device exhibits a low on-chip insertion loss of 5.4dB (coupling loss included) and high on-off extinction ratio more than 20dB. The modulation efficiency is estimated to be within 3-3.84V•cm. In order to investigate the fiber misalignment tolerance of this modulator, misalignment influence of the static characteristics is analyzed. 10Gb/s Data transmission experiments of this device are performed with different fiber launch positions. The energy efficiency is estimated to be 8.1pJ/bit.

Assessment of the impact of TS assimilation from ARGO floats in the Mediterranean Sea

Abstract. In this paper, the impact of assimilating Temperature (T) and Salinity (S) profiles from Argo floats in the Mediterranean Sea is quantitatively investigated using the Observing System Simulation Experiments (OSSE) approach. The impact of varying the number of floats and their launch positions is considered, using numerical simulations with a MOM model and a reduced-order multivariate Optimal Interpolation scheme (SOFA) for assimilation. Realistic float coverage and launch positions used during the first MFSTEP phase are considered, as well as "ideal" density coverage that can be envisioned for the future, corresponding to a double coverage with respect to MFSTEP and with floats released along the VOS tracks. The most effective float trajectories are identified, showing that frontal regions play a major role, and that it is crucial to maintain a sufficient coverage of them. In addition to this, a comparison is also performed between the results obtained from MEDARGO floats in ideal conditions and results from "ideal" profiles taken at fixed points along the VOS tracks, as for the XBT data. For consistency the coverage considered is double the actual XBT coverage during MFSTEP, resulting in a threefold increase in the number of profiles compared to the MEDARGO experiment. The maximum error reduction is of approximately 10%, suggesting that spatially coarser profiles from floats can be more efficient since they follow flow features.

MULTIBLOCK EULER COMPUTATION OF TRANSONIC FLOW ABOUT A GENERIC AIRCRAFT CONFIGURATION

SUMMARY An implicit, upwind numerical scheme is presented for computing the unsteady transonic flowfield around complex aircraft configurations. This scheme solves the time-dependent Euler equations with a finite volume method that incorporates a high resolution Riemann solver to define the interface fluxes. A multiblock domain decomposition appproach is used to partition the computational domain into a completely arbitrary arrangement of blocks. However, this work is restricted to C1-continuous grid lines across block boundaries. Consequently, block-block interfaces are treated such as to mimic interior block communication, thus introducing no additional spatial differencing error. Computational results have been obtained for a complete wing-pylon-store configuration with the store in the captive and vertical launch positions. The numerical results for both stationary and dynamic grids have shown favorable agreement with experimental data.

Complex differential games of pursuit-evasion type with state constraints, part 2: Numerical computation of optimal open-loop strategies

In Part 1 of this paper (Ref. 1), necessary conditions for optimal open-loop strategies in differential games of pursuit-evasion type have been developed for problems which involve state variable inequality constraints and nonsmooth data. These necessary conditions lead to multipoint boundary-value problems with jump conditions. These problems can be solved very efficiently and accurately by the well-known multiple-shooting method. By this approach, optimal open-loop strategies and their associated saddle-point trajectories can be computed for the entire capture zone of the game. This also includes the computation of optimal open-loop strategies and saddle-point trajectories on the barrier of the pursuit-evasion game. The open-loop strategies provide an open-loop representation of the optimal feedback strategies. Numerical results are obtained for a special air combat scenario between one medium-range air-to-air missile and one high-performance aircraft in a vertical plane. A dynamic pressure limit for the aircraft imposes a state variable inequality constraint of the first order. Special emphasis is laid on realistic approximations of the lift, drag, and thrust of both vehicles and the atmospheric data. In particular, saddle-point trajectories on the barrier are computed and discussed. Submanifolds of the barrier which separate the initial values of the capture zone from those of the escape zone are computed for two representative launch positions of the missible. By this way, the firing range of the pursuing missile is determined and visualized.

The absorption of electron cyclotron waves in the vicinity of an extremum of the equilibrium magnetic field

Local extrema in the equilibrium magnetic field strength can occur in tokamak plasmas when the plasma beta is increased. Furthermore, the magnetic field strength experienced by an electromagnetic wave propagating along a vertical chord in lower-beta tokamak plasmas may also pass through an extremum. For both these reasons, it is of interest to calculate the absorption of electron cyclotron waves in configurations where a harmonic of the cyclotron resonance lies near an extremum of the equilibrium magnetic field strength. It is shown that strong absorption can occur for both the O mode at second harmonic resonance and the X mode at third harmonic resonance, whereas absorption at these resonances is relatively weak when the gradient in magnetic field strength is linear. The optical depth in a magnetic field with parabolic scale length L is typically enhanced with respect to that in a field with linear scale length R by a factor cL/5vTR, where vT is the electron thermal velocity and c the velocity of light. Since electron cyclotron waves can reach these resonances in high-density plasma from launch positions on the low-field side of the tokamak, the number of effective and convenient electron cyclotron heating configurations is increased when the equilibrium magnetic field strength has local extrema.