In this paper, we propose a multi-environment, multi-LiDAR, multi-task dataset to promote the grid map-based navigation capability for autonomous vehicles. The dataset comprises structured and unstructured environmental data captured by different types of LiDAR and contains various challenging scenarios, including moving objects, negative obstacles, steep slopes, cliffs, overhangs, etc. Further, we have devised an innovative method for generating ground truth, facilitating the creation of dense, accurate, and stable grid maps with a minimal requirement for human annotation efforts. A new baseline method and two existing approaches are evaluated on this dataset. Results indicate that existing approaches perform much worse than the proposed baseline. The dataset will be made publicly available at https://github.com/guanglei96/M3-GMN.

It's challenging to balance the networks stability and plasticity in continual learning scenarios, considering stability suffers from the update of model and plasticity benefits from it. Existing works usually focus more on the stability and restrict the learning plasticity of later tasks to avoid catastrophic forgetting of learned knowledge. Differently, we propose a continual learning method named Split2MetaFusion which can achieve better trade-off by employing a two-stage strategy: splitting and meta-weighted fusion. In this strategy, a slow model with better stability, and a fast model with better plasticity are learned sequentially at the splitting stage. Then stability and plasticity are both kept by fusing the two models in an adaptive manner. Towards this end, we design an optimizer named Task-Preferred Null Space Projector(TPNSP) to the slow learning process for narrowing the fusion gap. To achieve better model fusion, we further design a Dreaming-Meta-Weighted fusion policy for better maintaining the old and new knowledge simultaneously, which doesn't require to use the previous datasets. Experimental results and analysis reported in this work demonstrate the superiority of the proposed method for maintaining networks stability and keeping its plasticity. Our code will be released.

Aim to improve the power density of the electromagnetic ejection system of UAV, the finite control set model prediction is adopted as the control strategy from the perspective of improving the efficiency. The semi-active control of hybrid energy storage system and the drive control of ejection motor are considered together. According to the different requirements of commutation and non-commutation, the finite control set of the electromagnetic ejection system is designed, control optimization is carried out from the system. Simulation results show that the proposed control strategy can effectively reduce thrust fluctuation, stabilize bus voltage, reduce switching loss and improve the efficiency of electromagnetic ejection system.

从5G视角出发阐释智慧阅读的演变优势和服务特点,基于5G+多元智能技术打造智慧阅读空间、阅读游戏开发、智慧阅读营销、阅读资源导航、阅读素养教育的服务体验.为完善5G模式下图书馆智慧阅读的发展格局,论文从维系阅读媒介生态、用户数据的规范与增效、融入情感交互、多样举措融合4个层面对智慧阅读的开展提出参考意见.

Three-dimensional (3D) point cloud maps are widely used in autonomous driving scenarios. These maps are usually generated by accumulating sequential LiDAR scans. When generating a map, moving objects (such as vehicles or moving pedestrians) will leave long trails on the assembled map. This is undesirable and reduces the map quality. In this paper, we propose MapCleaner, an approach that can effectively remove the moving objects from the map. MapCleaner first estimates a dense and continuous terrain surface, based on which the map point cloud is then divided into a noisy part below the terrain, the terrain, and the object part above the terrain. Next, a specifically designed moving points identification algorithm is performed on the object part to find moving objects. Experiments are performed on the SemanticKITTI dataset. Results show that the proposed MapCleaner outperforms state-of-the-art approaches on all five tested SemanticKITTI sequences. MapCleaner is a learning-free method and has few parameters to tune. It is also successfully evaluated on our own dataset collected with a different type of LiDAR.

A sensorless commutation control method based on the zero crossing principle of line back EMF is proposed for permanent magnet DC linear motor with distortion of opposite EMF. Through qualitative analysis of waveform and quantitative derivation of series theory formula, it is proved that even if the opposite potential is distorted, the zero point of line back potential is still consistent with the actual electronic commutation point of the system. At the same time, in order to avoid missing the zero point of line back EMF, a commutation control method based on s function is constructed. The simulation results show that the method meets the system requirements.

"以文促旅,以旅彰文"已经成为推动文化和旅游业发展的重要手段,公共图书馆作为重要的文化事业单位,需在推动文旅融合发展中发挥应有作用.文章分析了公共图书馆与旅游业融合发展的意义,研究了公共图书馆应对旅游业六要素差异化需求的不同服务方法,探讨了图书馆五要素融入旅游业发展的可行性路径,以期通过要素融合协同实现公共图书馆文旅融合发展的目的.

In order to meet the needs of the battlefield, a double-sided moving armature permanent magnet linear ejection motor with high maneuverability is proposed. The structure of the permanent magnet linear ejection motor with moving armature is optimized. By designing the self-alignment guide structure, the air gap can automatically tend to be symmetrical and the normal force caused by the asymmetry of the actuator can be weakened. The eddy current resistance in the process of launch can be effectively reduced by replacing supporting frame materials and applying stiffeners. In addition, the braking effect of the brake segment can be improved and the impact force can be reduced by changing the brake structure to hydraulic damping brake.

In order to solve the problem of large normal force of bilateral moving armature permanent magnet linear DC motor, Fourier expansion method was used to obtain the analytical expression of normal force on permanent magnet, considering the cogging effect. The research shows that the armature current can inhibit the normal force on the permanent magnet, but at the same time it increases the fluctuation of the normal force. The no-load normal force of the permanent magnet can be reduced by 440N by decreasing the pole arc coefficient and tooth width. Although part of the thrust performance is lost, the thrust of the linear motor can be compensated under the condition of higher current, and the thrust fluctuation is basically unchanged. The simulation results are basically consistent with the analytical results, which verifies the correctness of the analytical analysis method of normal force fluctuation.

为了对图书馆智能服务与智慧服务的本质进行区别,文章从概念鉴别、性质、功能和元素组件等方面对二者展开研究,指出图书馆智能服务的劣势、图书馆智慧服务的优势以及转型智慧化服务的必然性,最后从馆员素养提升、智慧化服务走向以及用户体验规划方面进行整合研究,为图书馆智慧服务的转型和定位提供借鉴.

High-speed maglev train speed measurement and positioning system is the basis of train traction and operation control. The existing relative position based on the principle of electromagnetic induction is vulnerable to electromagnetic interference and suspension gap fluctuations, which requires a lot of time to solve electromagnetic compatibility and other issues. In this paper, a data-driven relative position detection scheme based on laser displacement sensor combination is proposed for the high-speed maglev train speed measurement and positioning system. It uses a combination of laser displacement sensors to collect the vertical displacement signal and establishes the relative position detection model of one coggle cycle by designing a neural network to sense the periodic change of vertical displacement signal, which effectively overcomes the influence of suspension gap fluctuation. In order to improve the modeling accuracy, an adaptive fault-tolerant filtering algorithm is proposed, which can effectively overcome the effects of inconsistent width of the long stator surface, inconsistent depth of the stator cable depression, and foreign bodies on the stator surface. At the same time, the proposed scheme can determine the rail gap in real time, through the two detection signal switching mode can eliminate the influence of rail gap. The analysis and experimental results show that the proposed solution can effectively adapt to various conditions of vehicle operation, overcome the influence of electromagnetic interference and suspension fluctuations, and realize the high-precision positioning requirements of high-speed Maglev trains.

探讨未成年人阅读推广活动分类,阐述建立个人图书馆对于未成人阅读推广的意义,以扬州市少年儿童图书馆“个人图书馆计划”为例,介绍该馆个人图书馆服务实践及成效,分析服务中存在的问题,据此提出个人图书馆服务完善措施,以保障该服务在未成年人阅读推广中持续发挥作用.