Hasil untuk "Motor vehicles. Aeronautics. Astronautics"

QUAN Jingge, LI Hongjun, FENG Xiaoqiang et al.

The inlet/engine matching principle of target drone propulsion system is important to evaluate the engine working characteristics. To obtain the inlet/engine matching performance of a target drone, the investigation of the S-shaped inlet and small turbojet engine matching characteristic is carried out in this paper, by combining inlet/engine matching ground test with inlet suction experiment. It concentrates the influence of the S-shaped inlet on the engine characteristics. And an engineering method is produced to evaluate the small engine characteristics on ground running, by building the connections between the inlet/engine matching ground test and inlet suction experiment. It is shown that the performance of engine in matching ground test is mainly affected by the S-shaped inlet characteristic parameters. When the full scale S-shaped inlet installed, the engine performance is no longer as good as the craft inlet installed, but falls. As the engine rotating speed enhanced, the mass flow increases, and the inlet performance gets worse. The total pressure recovery coefficient at the inlet exit decreases and the distortion index rises, which has a negative effect on the engine performance, resulting in the thrust smaller and the fuel consumption larger.

Qinxin Xiao, Jiaojiao Gao

Urban logistics in smart cities are increasingly challenged by congestion, sustainability pressures, and the growing demand for resilient delivery systems. To address these challenges, this study introduces the Multi-Visit Time-Dependent Truck–Drone Routing Problem with simultaneous Pickup and Delivery (MTTRP-PD), a novel framework that integrates three realistic features: (i) drones serving multiple customers per sortie, (ii) time-dependent truck speeds reflecting dynamic traffic conditions, and (iii) synchronized pickup and delivery between trucks and drones. By incorporating these elements, the proposed model provides a more realistic and comprehensive representation of urban air-ground collaborative logistics in the last mile. An optimization framework and an efficient solution approach are developed and validated through computational experiments. The results demonstrate that enabling multi-visit sortie and simultaneous pickup–delivery operations can significantly reduce logistics costs compared with conventional single-visit or delivery-only strategies. Sensitivity analyses further reveal the critical influence of dynamic traffic conditions on fleet configuration and operational decision making. The findings offer actionable insights for logistics operators and policymakers, illustrating how coordinated UAV–truck collaboration can enhance efficiency, resilience, and environmental sustainability in next-generation urban logistics systems.

Qiangqiang Chen, Baisheng Liu, Changdong Yu et al.

In modern marine warfare, unmanned underwater vehicles (UUVs) have fast and efficient attack capabilities. However, existing research on UUV attack strategies is relatively limited, often ignoring the requirement for the effective allocation of different strategic value areas, which restricts its performance in the marine combat environment. To this end, this paper proposes an innovative UUV task allocation and saturation attack strategy. The strategy first divides the area according to the distribution density of enemy UUVs, and then reasonably allocates tasks according to the enemy’s regional value and the attack capability of our UUVs. Our UUVs then sail to the enemy area and are evenly distributed in the encirclement to ensure accurate saturation attacks. In the task allocation link, the grey wolf optimizer is improved by introducing Logistic chaos mapping and differential evolution mechanism, which improves the search efficiency and allocation accuracy. At the same time, the combination of the optimal matching algorithm and Bezier curve dynamic path control ensures the accuracy and flexibility of a coordinated attack. The simulation experimental results show that the strategy shows high attack efficiency and practicality in marine combat scenarios, providing an effective solution for UUV attack tasks in complex marine environments.

Duowen Chen, Liqi Zhou, Chi Guo

Existing RGB image-based object detection methods achieve high accuracy when objects are static or in quasi-static conditions but demonstrate degraded performance with fast-moving objects due to motion blur artifacts. Moreover, state-of-the-art deep learning methods, which rely on RGB images as input, necessitate training and inference on high-performance graphics cards. These cards are not only bulky and power-hungry but also challenging to deploy on compact robotic platforms. Fortunately, the emergence of event cameras, inspired by biological vision, provides a promising solution to these limitations. These cameras offer low latency, minimal motion blur, and non-redundant outputs, making them well suited for dynamic obstacle detection. Building on these advantages, a novel methodology was developed through the fusion of events with depth to address the challenge of dynamic object detection. Initially, an adaptive temporal sampling window was implemented to selectively acquire event data and supplementary information, contingent upon the presence of objects within the visual field. Subsequently, a warping transformation was applied to the event data, effectively eliminating artifacts induced by ego-motion while preserving signals originating from moving objects. Following this preprocessing stage, the transformed event data were converted into an event queue representation, upon which denoising operations were performed. Ultimately, object detection was achieved through the application of image moment analysis to the processed event queue representation. The experimental results show that, compared with the current state-of-the-art methods, the proposed method has improved the detection speed by approximately 20% and the accuracy by approximately 5%. To substantiate real-world applicability, the authors implemented a complete obstacle avoidance pipeline, integrating our detector with planning modules and successfully deploying it on a custom-built quadrotor platform. Field tests confirm reliable avoidance of an obstacle approaching at approximately 8 m/s, thereby validating practical deployment potential.

Shantanu S. Bhat, Sreenatha G. Anavatti, Matthew Garratt et al.

Autonomous blimps have potential applications in surveillance, monitoring, and advertising. Due to their lower payload capacities and possible unstable flight profile, small blimps have been mostly used in indoor applications. However, recent advancements in their design and control have increased the prospects of deploying them for outdoor applications. This study presents a literature review of various aspects that encompass the unique elements of blimps’ design and operations followed by a discussion on the modern applications. The review focuses on advancements made in the fundamental attributes of blimps, including design, propulsion, navigation, and control. The review reveals that recent successes in using blimps for various missions, where heavier-than-air platforms have been usually used, highlight the potential for blimps to offer a lightweight and low-risk alternative. The relatively stable operation of blimps in low winds and longer-duration hovering capability can make them a preferred platform for rescue, source localization, and space applications. However, their stability in extreme environments is a challenge, in addition to their lower mobility and problems in accurately predicting control parameters. Thus, this review concludes with an overview of blimps’ futuristic applications of miniature blimps and recommendations to address the challenges in using them in real-world missions.

YI Shanshan, FENG Jiawen, LIU Qiang et al.

The as-cast microstructure of 2024 high-strength aluminum alloy has an important effect on its thermal workability and end-use performance.The effects of Cu/Mg ratio and solidification rate on as-cast microstructure were investigated by regulating the Cu and Mg content and solidification rate of 2024 alloy. The results show that with the mass ratio of Cu/Mg increases from 2.1 to 4.1，the type of second phase in the alloy is not changed. However，the content of Al2CuMg gradually decreases，while the content of Al2Cu and Al23Cu（Fe，Mn） 4 gradually increases.When the solidification rate increases from 0.2 ℃/s to 2.4 ℃/s，the grain size is obviously refined，the average grain size decreases from 293.0 μm to 77.0 μm. Moreover，the dendrites become developed，and the dendrite arm spacing decreases，and the second phase becomes smaller and distributes more homogeneous in the matrix，and the content of Al23Cu（Fe，Mn） 4 insoluble phase obviously reduces. The formation of iron-rich insoluble phase can be reduced by reducing the Cu/Mg ratio and increasing the solidification rate，so as that the machining and mechanical properties of the alloy can be improved.

Shihang Yang, Xin Jin, Baichun Gong et al.

Orbital maneuver detection for non-cooperative targets in space is a key task in space situational awareness. This study develops a passive maneuver detection algorithm using line-of-sight angles measured by a space-based optical sensor, especially for targets in high-altitude orbit. Emphasis is placed on constructing a new characterization for maneuvers as well as the corresponding detection method. First, the concept of relative angular momentum is introduced to characterize the orbital maneuver of the target quantitatively, and the sensitivity of the proposed characterization is analyzed mathematically. Second, a maneuver detection algorithm based on the new characterization is designed in which sliding windows and correlations are utilized to determine the mutation of the maneuver characterization. Subsequently, a numerical simulation system composed of error models, reference missions and trajectories, and computation models for estimating errors is established. Then, the proposed algorithm is verified through numerical simulations for both long-range and close-range targets. The results indicate that the proposed algorithm is effective. Additionally, the sensitivity of the proposed algorithm to the width of the sliding window, accuracy of the optical sensor, magnitude and number of maneuvers, and different relative orbit types is analyzed, and the sensitivity of the new characterization is verified using simulations.

Yan Xiaowei, Chen Dong

With the rapid development and application of computer technology and machine vision technology, the exploration of unexploded submunition search technology based on “artificial intelligence +” model has received extensive attention. However, due to the danger of unexploded submunitions and the particularity of military applications, data set construction is a bottleneck problem that needs to be solved urgently. Based on this, the paper discusses the construction methods and processes of real physical image data sets and three-dimensional reconstruction data sets using physical images. It focuses on the analysis of the key technologies and their advantages and disadvantages in the construction process of the two data sets. A multi-camera is used to collect the target image and geographic coordinate information, and then the deep learning algorithm is used to extract the target feature, generate the three-dimensional point cloud and fuse the three-dimensional image. The experimental results show that the three-dimensional data set constructed by this method can effectively solve the problem of insufficient data volume of the existing data set of unexploded submunitions. Finally, the future development direction of the data set construction method is prospected.

Oleg Vishnyakov, Pavel Polivanov, Andrey Sidorenko

The paper focuses on the investigation of unsteady effects in shock wave/boundary layer interaction. The study was carried out using a flat plate model subjected to a free stream Mach number of 1.43 and a unit Reynolds number (Re₁) of 11.5 × 10⁶ 1/m. To generate two-dimensional disturbances in the laminar boundary layer upstream of the separation region, a dielectric barrier discharge was employed. The disturbances were generated within the frequency range of 500 to 1700 Hz. The Strouhal numbers based on the length of the separation bubble ranged from 0.04 to 0.13. The measurements were carried out using a hot-wire anemometer. Analysis of the data shows that disturbances in this frequency range mostly decay. The maximum amplitudes of perturbations were observed at frequencies of 1250 Hz and 1700 Hz.

Lu Zhang, Hongyu Yang, Xiping Wu

Air traffic management (ATM) relies on the running condition of the air traffic control sector (ATCS), and assessing whether it is overloaded is crucial for efficiency and safety for the entire aviation industry. Previous approaches to evaluating air traffic complexity in a sector were mostly based on aircraft operational status and lacked comprehensiveness of characterization and were less adaptable in real situations. To settle these issues, a deep learning technique grounded on complex networks was proposed, employing the flight conflict network (FCN) to generate an air traffic situation graph (ATSG), with the air traffic control instruction (ATCOI) received by each aircraft included as an extra node attribute to increase the accuracy of the evaluation. A pooling method with a graph neural network (GNN) was used to analyze the graph-structured air traffic information and produce the sector complexity rank automatically. The model Hierarchical Graph Representing Learning (HGRL) was created to build comprehensive feature representations which involve two parts: graph structure coarsening and graph attribute learning. Structure coarsening reduced the feature map size by choosing an adaptive selection of nodes, while attribute coarsening selected key nodes in the graph-level representation. The experimental findings of a real dataset from the Chinese aviation industry reveal that our proposed model exceeds prior methods in its ability to extract critical information from an ATSG. Moreover, our work could be applied in the two main types of sectors and without extra factor calculations to determine the complexity of the airspace.

William R. Koski, Brent G. Young

Effective management of animal populations requires knowledge of life history parameters and estimates of population abundance. One method commonly used to estimate abundance is capture–recapture analyses of photographs. Small, relatively inexpensive, rotary-wing drones have become an effective platform for obtaining high-quality aerial photographs of whales. To conduct capture–recapture analyses the animal needs to be defined as marked or unmarked and the photographs must be of high quality. While a system for scoring quality and markedness has previously been developed for bowhead whales (Balaena mysticetus Linnaeus, 1758) (Rugh et al. 1998. Rep. int. Whal. Commn. 48: 501–512), a revised scoring system was needed to incorporate increased information in photographs taken by drones. We present a revised scoring system that enlarges two of the previously defined areas of the whale examined for markings and incorporates smaller markings into the definition of marked whales. We scored 30 whales using the previous criteria and the revised criteria developed in this paper. More whales were identified as marked (23%) and mark scores were higher for 30% of the zones scored using the new system. Increasing the number of marked whales during capture–recapture studies increases the precision of estimated parameters and permits us to make those estimates with smaller samples of photographs.

Wanqing Zhang, Wanchun Chen, Wenbin Yu

A new, highly constrained guidance law is proposed against a maneuvering target while satisfying both impact angle and terminal acceleration constraints. Here, the impact angle constraint is addressed by solving an optimal guidance problem in which the target’s maneuvering acceleration is time-varying. To deal with the terminal acceleration constraint, the closed-form solutions of the new guidance are needed. Thus, a novel engagement system based on the guidance considering the target maneuvers is put forward by choosing two angles associated with the relative velocity vector and line of sight (<i>LOS</i>) as the state variables, and then the system is linearized using small angle assumptions, which yields a special linear time-varying (LTV) system that can be solved analytically by the spectral-decomposition-based method. For the general case where the closing speed, which is the speed of approach of the missile and target, is allowed to change with time arbitrarily, the solutions obtained are semi-analytical. In particular, when the closing speed changes linearly with time, the completely closed-form solutions are derived successfully. By analyzing the generalized solutions, the stability domain of the guidance coefficients is obtained, in which the maneuvering acceleration of the missile can converge to zero finally. Here, the key to investigating the stability domain is to find the limits of some complicated integral terms of the generalized solutions by skillfully using the squeeze theorem. The advantages of the proposed guidance are demonstrated by conducting trajectory simulations.

Haoyu Chen, Emir Yilmaz, Koki Asano et al.

To improve the thermal efficiency of ICEs, effective control of in-cylinder temperature is important. Utilization of nucleate boiling phenomenon to model the heat transfer is one of the measures that can be used for this purpose. Surface heat flux and bubble departure frequency measurements were done under the different wall superheat, coolant flow-rate, and temperature conditions. Subsequently, dimensional analyses were done to investigate the necessary dimensionless numbers acting on the heat flux model. The addition of power and exponential function of Jakob number was found to be effective, resulting in an average and minimum errors of 11.2% and 6.5%, respectively.

Emre Arabacı

In this study, displacement, velocity and acceleration equations were obtained for the mechanism created by modifying the long-stroke reciprocating mechanism. Thus, a novel mechanism has been created. In addition, the effects of the design parameters were examined and the results obtained were compared with the conventional crank-connecting rod mechanism. While the crank radius (r) and connecting rod length (L), which are the main design parameters of the conventional crank-connecting rod mechanism, are fixed, the design parameters of the novel mechanism are changed and the effects of these design parameters on the velocity and acceleration characteristics are examined. For the novel mechanism, the ratio of the inner gear radius to the pinion gear radius (r2/r1=k) and the ratio of the output gear radius to the pinion gear radius (r0/r1=m) are determined as the basic design parameters. Accordingly, by decreasing k and increasing m, it was seen that the connecting rod angle, mean piston velocity, and mean piston acceleration were decreased. The correct choice of k and m shows that the novel mecha-nism can be made more advantageous compared to the conventional crank-connecting rod mechanism. The results are predicted to be promising for engine designers.

İbrahim Can Güleryüz

Reducing vehicle weight without compromising performance becomes an area which is important to improve fuel economy and reduce vehicle emissions. The possibility of reducing unsprung mass in a vehicle has led to many investigations of weight optimization studies of axle and wheel-end components. Therefore, structural design of a torque plate, which is one of the main parts of a Z-cam drum brake used in heavy-duty vehicles, is carried out by using topology optimization and finite element analyses. Firstly, finite element analysis of the original torque plate is conducted to determine critical stress levels and locations. Secondly, topology optimization is carried out on the original torque plate for specified loading conditions. Taking redundant volume and manufacturability constraints into account a new torque plate design is composed. Finally, finite element analysis is repeated to verify the final design. A significant decrease in stress level is accompanied by considerable reduction in casting and machined part masses by 11.9% and 12.2% respectively.

Black David, Calverley Stuart, Birchall Jeff

This paper will describe the journey of magnetic powersplit powertrain technology from its origins in new technology discovery through to packaged, design intent vehicle applications, describing the obstacles overcome and opportunities realised in the journey that delivered magnetic powersplit technology to Global Automotive OEM's. Aspects of technology development, design for manufacture, capability proving and production feasibility will be described in order to demonstrate a credible, world class next generation hybrid powertrain.

E. A. Kuklev, Yu. Yu. Mihalchevskiy, M. Yu. Smurov

The ways of constructing the processes of change in discreet states of the «Crew-Aircraft-Medium-ATC» system in modeling the technology of operating the aircraft after the crew have taken the decision «Go around» as recommended by a controller.

Paulo Cesar de Carvalho Faria, Koshun Iha, José Atílio Fritz Fidel Rocco

Electro-explosive devices (an electric resistance encapsulated by a primary explosive) fundamentally convert electrical energy into thermal energy, to start off an explosive chemical reaction. Obviously, the activation of those devices shall not happen by accident or, even worse, by intentional exogenous influence. From an ordinary differential equation, which describes the electro-explosive thermal behavior, a remarkable, but certainly not intuitive, dependence of the temperature response on the time constant of the heat transfer process is verified: the temperature profile dramatically changes as the time constant spans a wide range of values, from much lesser than the pulse width to much greater than the pulse period. Based on this dependence, important recommendations, concerning the efficient and safety operation of electro-explosive devices, are proposed.

David A. Peters, Xi Rong

A set of systematical optimum operational parameters for wind turbines under various wind directions is derived by using combined momentum-energy and blade-element-energy concepts. The derivations are solved numerically by fixing some parameters at practical values. Then, the interactions between the produced power and the influential factors of it are generated in the figures. It is shown that the maximum power produced is strongly affected by the wind direction, the tip speed, the pitch angle of the rotor, and the drag coefficient, which are specifically indicated by figures. It also turns out that the maximum power can take place at two different optimum tip speeds in some cases. The equations derived herein can also be used in the modeling of tethered wind turbines which can keep aloft and deliver energy.

V. Jones, K. Shukla