Maximum Overload Research Articles

A novel evasion guidance for hypersonic morphing vehicle via intelligent maneuver strategy

This paper presents a novel evasion guidance law for hypersonic morphing vehicles, focusing on determining the optimized wing's unfolded angle to promote maneuverability based on an intelligent algorithm. First, the pursuit-evasion problem is modeled as a Markov decision process. And the agent's action consists of maneuver overload and the unfolded angle of wings, which is different from the conventional evasion guidance designed for fixed-shape vehicles. The reward function is formulated to ensure that the miss distances satisfy the prescribed bounds while minimizing energy consumption. Then, to maximize the expected cumulative reward, a residual learning method is proposed based on proximal policy optimization, which integrates the optimal evasion for linear cases as the baseline and trains to optimize the performance for nonlinear engagement with multiple pursuers. Therefore, offline training guarantees improvement of the constructed evasion guidance law over conventional ones. Ultimately, the guidance law for online implementation includes only analytical calculations. It maps from the confrontation state to the expected angle of attack and the unfolded angle while retaining high computational efficiency. Simulations show that the proposed evasion guidance law can utilize the change of unfolded angle to extend the maximum overload capability. And it surpasses conventional maneuver strategies by ensuring better evasion efficacy and higher energy efficiency.

Multi-Objective Optimization Design of an Origami-Inspired Combined Cushion Airbag

To improve the cushioning performance of soft-landing systems, a novel origami-inspired combined cushion airbag is proposed. The geometry size, initial pressure, and exhaust vent area of the cushion airbags are designed preliminarily using a theoretical model. The finite element models, including the returnable spacecraft and cushion airbags, are established via the control volume method (CVM) to analyze the impact dynamic behavior and cushioning performance during the landing attenuation process. The cushioning performance of the cushion airbags in complex landing environments are studied to investigate the influence of horizontal velocity, lateral velocity and nonhorizontal landing surfaces. Four design parameters of the cushion airbags, including the initial pressure, venting threshold pressure, exhaust vent area and polygon edge number, are employed to study their influence on the cushioning performance. A multi-objective optimization model of the cushion airbags based on the neural network and multi-objective water cycle algorithm is established to realize the rapid optimization design. The Pareto front of the maximum overload and specific energy absorption is obtained. The analysis results show that the maximum overload of the proposed combined cushion airbags is 7.30 g. The system with the anti-rollover design can avoid rollover and achieve outstanding cushioning performance in complex landing environments. The maximum overload of the returning spacecraft is decreased by 16.4% from 7.30 g to 6.10 g after multi-objective optimizations. This study could provide the technical support for the soft-landing system design of returnable spacecrafts.

Four-Dimensional Trajectory Planning Algorithm for Fixed-Wing Aircraft Formation Based on Improved Hunter—Prey Optimization

The aircraft four-dimensional trajectory planning is an important technology for multiple aircraft to achieve cooperation. However, the current four-dimensional trajectory planning technology is mainly used for civil aviation and helicopters and is difficult to meet the requirements of fixed-wing aircraft. This paper proposed a four-dimensional trajectory planning algorithm for a fixed-wing aircraft formation, considering the speed range, turning radius and maximum overload. The improved tau-J strategy (ITJS) is used to generate the four-dimensional trajectory of the aircraft. This strategy is a bio-inspired trajectory planning algorithm that can generate a four-dimensional trajectory with continuous acceleration. Furthermore, the improved hunter–prey optimization (IHPO) algorithm is used to optimize the trajectory to make the generated trajectory meet the constraints and speed up the algorithm convergence. This algorithm improves the updated strategy and initialization strategy based on the hunter–prey optimization (HPO) algorithm, which prevents the algorithm from falling into local optima. The results of the benchmark test function show that the optimization result of the algorithm is improved by more than 10% compared with the original HPO algorithm. The simulation results show that the proposed algorithm jumps out of local optima and generates a trajectory that meets the constraints.

Study of the Ejection Process of Cold Ejection System with Flexible Cylinder by Corpuscular Method

Cold ejection is widely used in the realm of ejection, but conventional ejection systems can’t adapt to the modern war due to obvious infrared characteristics and high energy consumption, so new ejection system is desired. This work demonstrates a new way of flexible ejection, which is based on control method and corpuscular Method. Firstly, a finite element model of the flexible cylinder ejection system is established. Then, the corpuscular method is applied to study the influence of length and cross-section diameters of the cylinder on the dynamic of ejection process. It is found that the length of flexible cylinder will prolong the time of ejection from 0.72s to 1.01s with length increase from 7.2m to 10.4m. However, the diameter decreases the ejection time. Meanwhile, the velocity increases from 14.37m/s to 15.46m/s with cross-section diameter of cylinder increases from 0.60m to 0.75m. And the maximum overload is bigger 25.9 % than minimum.

Internal Ballistic Modeling and Simulation Analysis of High-low Pressure Low-overload Launch of Unmanned Aircraft

The low-overload launch is an important research direction in weapon launch. In this paper, a new low-overload launch method is designed by using the piston-type high-low pressure launch principle combined with the secondary launch principle. Based on the classical internal ballistic equations and multi-body dynamics equations, the internal ballistic model of this low overload launch system is established. A joint simulation model based on MATLAB and RecurDyn is constructed to simulate the internal ballistic state during the launch process. The sensitivity of each parameter change of the high-low pressure system to the launch overload is also studied. The results show that the maximum low-pressure chamber pressure of the low overload launcher in this paper is reduced by 62% compared to the conventional internal ballistic pressure, the saturation of the pressure curve is also improved, and the muzzle velocity is accelerated; the maximum overload is reduced by 65%, which can meet the requirements of muzzle initial velocity and low overload when launching unmanned aircraft.

Optimal Cooperative Guidance Strategies for Aircraft Defense with Impact Angle Constraints

Given the limitations of escape maneuvers and decoy deployment of combat aircraft under missile attacks; active defense dramatically improves the survival chances by launching active defense missiles to intercept incoming missiles. Different from previous work, this paper implemented impact angle constraints on the defense missile to achieve a better defense effect. The low-cost active defense missile with limited maneuverability is considered to cooperate with the aircraft through three mechanisms, namely two-way cooperation without any predetermined strategy, one-way cooperation with the defense missile employing a linear guidance strategy, and one-way cooperation with independent evasion maneuver for the target. Three optimal cooperative guidance strategies with impact angle constraints were investigated. Finally, a nonlinear two-dimensional model for agents with first-order autopilot dynamics was simulated to verify the performance of the proposed strategies. The simulation results indicated that the cooperative mechanism directly affects the available range of impact angles, and the constraints of a big impact angle can be realized by introducing the nonlinear model parameters and considering the angle variation between the velocity vector and the initial line-of-sight. Furthermore, the two-way cooperative mechanism achieves the best performance and more flexible solutions to accommodate different vehicle maximum overload limits.

Численный анализ проникания в бетонную преграду макетов ударников с учетом влияния отделяемого поддона

Numerical simulation within the framework of two-dimensional axisymmetric problem of continuum mechanics made it possible to analyze penetration into a semi-infinite concrete barrier with impactor models having diameter of 14 and 18 mm and initial speed of 1200 m/s. Influence of the detachable pallet used to accelerate the models in the ballistic installation barrel was both taken into account and not taken into account. Within the penetration process, the impactor models and the pallets were considered to be the absolutely rigid non-deformable bodies. The impactor model head was conical with or without a nasal blunt. Positive effect of blunting the head was established on the dynamics of penetration of the impactor models, which resulted in the increase in their penetration depth and the decrease in the maximum overload caused by the cavitation effect manifestation with the presence of blunting. When simulating penetration of the impactor models installed in a detachable pallet, a decrease was registered in the penetration depth by slightly more than 10% with an increase in the maximum overload compared to the case of penetration with a missing pallet. The negative influence reason of the pallet on the impactor models penetration was revealed. It consists in an increase in the shear stresses acting on the model contact surfaces with the adjacent layer of the destroyed concrete caused by compression of this layer by the pallet, until the pallet is completely separated from the impactor model.

Расширение возможных областей посадки на поверхности Венеры с использованием гравитационного маневра

In the framework of the project "Venera-D" a problem of landing the descent module in a given area of the surface of Venus is considered. With the standard approach to selection of the launch window and with limitations on the value of the re-entry angle into the atmosphere, as well as on the maximum allowable overload for lander during descent, a significant part of the planet’s surface is inaccessible for landing. The simplest way to expand the landing area could be to increase the launch window by moderate reducing the payload mass. However, the potential for such an increase is significantly limited, primarily by the required characteristic velocity cost. In this study a new approach is proposed to ensure landing of the descent module at any point on the surface of Venus. The basis of the proposed approach is the use of the gravitational field of the planet to transfer the spacecraft to the heliocentric orbit, resonant at a ratio of 1:1 with the orbit of Venus, and the subsequent return to its original position in one Venusian year, when another part of the surface will be available for landing. In the presented paper it is shown that application of new approach allows to provide radical expansion of achievable landing areas, and also to provide access to any point on the surface of Venus due to increase of duration of flight and small increase of characteristic velocity costs

Optimal Weighted Load Balancing in TCAMs

Traffic splitting is a required functionality in networks, for example for load balancing over multiple paths or among different servers. The capacities of the servers determine the partition by which traffic should be split. A recent approach implements traffic splitting within the ternary content addressable memory (TCAM), which is often available in switches. It is important to reduce the amount of memory allocated for this task since TCAMs are power consuming and are often also required for other tasks such as classification and routing. Previous work showed how to compute the smallest prefix-matching TCAM necessary to implement a given partition exactly. In this paper we solve the more practical case, where at most <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n$ </tex-math></inline-formula> prefix-matching TCAM rules are available, restricting the ability to implement exactly the desired partition. We give simple and efficient algorithms to find <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$n$ </tex-math></inline-formula> rules that generate a partition closest in <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L_\infty $ </tex-math></inline-formula> to the desired one. We do the same for a one-sided version of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$L_\infty $ </tex-math></inline-formula> which equals to the maximum overload on a server and for a relative version of it. We use our algorithms to evaluate how the expected error changes as a function of the number of rules, the number of servers, and the width of the TCAM.

Test and Improvement of a Fuze MEMS Setback Arming Device Based on the EDM Process.

This paper introduces the working principle of a MEMS safety and arming (S&A) device for a fuze that is installed perpendicular to the axis of the projectile. Additionally, the application of low-speed wire electrical discharge machining (EDM) in the fabrication of the device is proposed. Microsprings are susceptible to flexural deformation and secondary deformation in the EDM process, a problem that is solved by designing the auxiliary support beam, using multiple cuts, destress annealing and optimizing the processing parameters. The difficult problem of setback slider deformation in the principle prototype test is properly solved by establishing V-shaped grooves at both ends of the setback slider. The connection mode between the microspring and the frame is changed to a clearance fit connection. The improved setback arming device can guarantee service process safety and launch reliability. The maximum overload that can be withstood in service processing is 20,000 g, and the minimum overload for safety release during launch is 12,000 g. The results show that the EDM process can greatly reduce the machining cost while improving the machining precision and machining speed, which can compensate for the defects of the current manufacturing technology.

Overload performance study and fabrication of the capacitive pressure-sensitive chip with linkage film.

In order to satisfy the demands of pressure measurement under high overload conditions, the overload characteristics of the capacitive pressure-sensitive chip with linkage film are studied. Through the simulation and analysis for the stress distribution of this sensitive structure and in light of the dimension effect of the tensile strength of monocrystalline silicon, the influence of sizes of the sensitive structure on the overload pressure is expounded. The simulated results illustrate that the maximum overload pressure can exceed 200 times the full-scale (FS) when appropriately adjusting the sizes of the sensitive structure. The proposed chip is fabricated using SOI wafers combined with bonding technology. Our experimental results show that the sample chip has a linear response in the pressure range of 25-100kPa, and its overload pressure is 4.5 MPa, reaching 45 times the full-scale.

Time-dependent reliability of concrete bridges considering climate change and overload

Increased temperature and carbon dioxide concentration caused by climate change will aggravate the creep shrinkage and structural durability of concrete bridges. Overloading also has a great impact on the time-dependent reliability of existing bridges. This research paper analyses the time-dependent reliability of bridges based on climate change and overload. By improving the concrete carbonation model and referring to the B4 model of concrete creep, the effects of ambient temperature and humidity on concrete under different emission-reduction scenarios were considered. At the same time, given the serious problems of vehicle overload in China, combining different overload scenarios with climate change led to the establishment of a time-dependent reliability model for precast-concrete bridges. The results showed that as the overload rate increased, the time-dependent reliability degradation rate of a case study bridge accelerated. Under the scenario considering both high greenhouse gas emissions and the maximum overload rate, the service life of the case study bridge decreased to 50% of its design life.

A 4 × 10 Gb/s Adaptive Optical Receiver Utilizing Current-Reuse and Crosstalk-Remove

This article presents a $4 \times 10$ Gb/s low-noise adaptive optical receiver, utilizing a current-reuse architecture and channel crosstalk-remove techniques in 65-nm CMOS process. The receiver integrates a transimpedance amplifier (TIA), a continuous-time linear equalizer (EQ), high-gain and high-bandwidth limiting amplifiers, and a 50- $\Omega $ output driver into a single die. The TIA employs a common-source-based pseudo-differential topology with input series inductive peaking and $g_{m}$ -enhancement to improve bandwidth and noise performance. An automatic-gain-control loop scheme is presented which solves the bandwidth variation issue caused by variation of the TIA input impedance, across a large dynamic range of a small input to a maximum overload current. Multiple crosstalk reduction techniques are adopted to improve the channel isolation performance. The 850-nm vertical cavity surface emitting laser (VCSEL)-based full-link measurement results show that the optical receiver achieves $20.4~\mu \text{A}_{\mathrm {pp}}$ sensitivity bit-error-rate (BER $ -12) with a 200-fF photodiode, competitive with other prior CMOS-based TIAs. The crosstalk over different channels is also measured, demonstrating only a sensitivity penalty of 1 dB.

Temperature rise simulation model of RMU with switchfuse combinations for future load profiles

The load profiles on distribution networks have known an amplification and fluctuation of their peaks due to the raise of consumption and the expansion of the electric vehicles market. From a temperature rise point of view, the load increase has a direct impact on the heat dissipation of the fuses used within the RMU. The aim of this study is to provide, based on a defined experimental protocol, a simulation model that allows to determine the temperature rise at the most critical locations inside the RMU and accordingly to define the corresponding distribution transformer load and maximum overload duration.

Scientific basis for the trainer aircraft anti-g equipment requirements

The design process of a new aircraft (AC) is always associated with the issue of choosing its basic technical parameters, or, in other words, the formation of its conceptual design. In case of a civil aircraft, the choice of these parameters is defined by the requirements for operational safety, market conditions, norms that specify the tolerable harmful impact of the aircraft on the environment, etc. In case of a military aircraft, its outlay mostly depends on the concept of potential military threats, ways of using the military aircraft in military conflicts. Some of these requirements are formulated in regulatory documents – the Aviation Requirements for Civil Aircraft and the General Tactical and Technical Requirements of the Air Force for Military Aircraft. For example, Part 25 of the Aviation Requirements for Civil Aircraft defines the Airworthiness Standards for transport aircraft. It should be noted that the stated above requirements are often a tool of competition, for example, when tightening the aircraft noise abatement procedures provides advantages for particular manufacturers, not admitting other manufacturers to enter the market, whose aircraft do not conform to the new standards. Thus, complying with the requirements virtually involves additional costs both in the aircraft development and during its operation. In addition, the implementation of the requirements stated above can lead to the deterioration of the aircraft’s performance, and hence, to the decrease of its competiveness and combat effectiveness. Therefore, each requirement of the regulatory documents should have a profound scientific rationale. This article analyzes one of the regulatory documents requirements referring to the necessity of anti-g system on board aircraft. The authors propose the approach to specify the existing criterion to provide the scientific basis for the anti-g system on board aircraft by assessing the actual level of pilot load when maneuvering. The subject under study is of particular importance for the Yak-152 trainer aircraft. The actual level of loads during pilotage of the Yak-152 trainer aircraft does not require the use of the anti-g system but if to be based on a formal criterion, namely, in terms of the maximum operational overload value, the aircraft should be fitted out with such a system.

Research on Oblique Penetration of Projectiles into Targets of Different Materials

In order to study the trajectory deflection of projectile penetrating obliquely into different materials, the Lagrange algorithm of LS-DYNA was used to simulate the three-dimensional model. The impact angle of projectile is 70°, the concrete target and the soil target are penetrated respectively. The state of the target, the strain nephogram and the stress nephogram of the target under the maximum overload are obtained. The curves of penetration depth, penetration velocity, overload and energy are analyzed. The results show that: in oblique penetration, the projectile’s trajectory deflects more in the process of entering the concrete target, and then deflects less; the trajectory deflection of the projectile is small in the process of entering the soil target and a certain distance after it, but it becomes larger when it is fast out of the target.

Numerical Simulation Study on Propellant Stability of Penetration Warhead

For the problem of charge stability of penetration warhead with a booster device. The process of projectile penetrating concrete is simulated by ANSYS/LS-DYNA with two different algorithms (FEM and FEM-SPH), the calculation results of numerical simulation and experience formula were contrasted with the experimental data. The results show that the FEM-SPH coupling algorithm can overcome the shortage of traditional finite element algorithm for dealing with large deformation issue. and the calculation result of FEM-SPH is most closely with the experimental data. The propellant structure can withstand the maximum overload is 29134g. It can provide a reference for the design of the booster warhead.

Effects of artificial gravity on perimetry results

To study the effects of artificial gravity on the perimetry measurements of the eye. The study included 9 volunteers (men) aged 31.2±6 years (from 25 to 40 years). Each man was subjected to three rotations on SRC. The operative factor in the tests was overloads in the «head-pelvis» direction. Rotations were carried out in three different modes with varying maximum overload value at the feet level of up to 2.0; 2.4; 2.9 G. Pulsar-perimetry was carried out before and 1-2 hours after the rotations estimating the mean threshold of retinal photosensitivity Mean Sensitivity (MS), mean loss of sensitivity Mean Defect (MD), square root of Loss Variance (sLV); the Bebie curve; additionally, cluster analysis was performed. Mean threshold of retinal photosensitivity, mean loss of photosensitivity, square root of Loss Variance by Pulsar-perimetry before (MS=22.75 dB; MD= -0.6 dB; sLV=1.5) and after rotations on SRC (in Mode 1: 23.4; -0.2; 1.5, Mode 2: 23.2; -0.4; 1.4 and Mode 3: 23.5; -0.8; 1.4 respectively) did not change significantly. No adverse phenomena were detected in the eyes. There were no significant changes in the visual fields of the test subjects after rotations in three different modes according to Pulsar-perimetry data, which gives reason to tentatively conclude that using SCR in these modes is safe for the visual sensory system. According to preliminary data, this method can be successfully used to reduce the risk of long-term space flights and prevent unwanted phenomena caused by weightlessness.

Influence of overloaded vehicles on pavement life based on WIM data

In this paper, the weight distribution characteristics of overloaded vehicles and the influence of overloaded vehicles on pavement service life are studied based on WIM data. Based on the vehicle weight data collected from weight in motion station, the vehicle weight distribution function of different axle type trucks and the weight overload ratio distribution function of different axle types are obtained by fitting. Equivalent single axle loads of the pavement under different weight limits are calculated based on the vehicle weight distribution function, and finally the pavement life growth factors under different weight limits are determined. The calculation results show that: the maximum overload ratio of two-axle vehicle can reach 340%; the number of six-axle overloaded vehicle accounts for more than 50% of the total number of overloaded vehicles, which is the largest proportion. Pavement life can be improved effectively by limiting load, and the road life growth factor shows a quadratic parabolic trend to increase with the decrease of load limit value. For two axle trucks with serious overload, the pavement life can be increased by more than 15 times with a strict load limit value.

Study on the Composite Structure of Aluminum Foam-Filled Thin-Walled Metal Tube to Reduce the Charge Overload inside the Projectile during the Penetration Process

When a projectile penetrates a target at high speed, the charge loaded inside the projectile usually bears a high overload, which will consequently severely affect its performance. In order to reduce the overload of the charge during the penetration process, the structure of the projectile was improved by adding two buffers at both ends of the charge. In this study, the mathematical expressions were first gained about the axial buffering force generated by the thin-walled metal tube, aluminum foam, and the composite structure of aluminum foam-filled thin-walled metal tube when they were impacted by the high-speed mass block through reasonable assumptions and stress analysis. During the experiment on the high-speed projectile penetrating reinforced concrete target, the acceleration curve of the charge and the projectile body were obtained. The results show that the maximum overload that the charge was subjected to during the launch and penetration process was significantly reduced, and the change in overload, which the charge was subjected to during the penetration process, was also less obvious.