Shenyang Institute of Automation,Chinese Academy Of Sciences
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Brain-Inspired Fast Saliency-Based Filtering Algorithm for Ship Detection in High-Resolution SAR Images
No full textIn this article, we aim to improve the performance of synthetic aperture radar (SAR) ship detection under complex conditions. The complex backgrounds are commonly encountered for high-resolution (HR) SAR ship detection data set, and they greatly influence the detection performance of ships. In recent years, deep neural networks (DNNs) have made substantial improvements on detection by adopting data augmentation. However, the improvement is limited since the models are sensitive to noise. To address this problem, a Fast Saliency-based Filtering algorithm (FSF) is proposed to filter out interference information. The FSF method is inspired by the filtering mechanisms of the human brain, which help people filter out target-irrelevant information fast to better extract target-relevant information. The FSF includes two parts of the bottom-up process and the top-down process. The bottom-up process is used to extract a saliency map of an input image, and the other one is used to filter out target-irrelevant information based on the saliency map. The FSF can be a front-end preprocessing module of DNNs to fast filter out target-irrelevant information and obtain a primary priority map of an input image. Experimental results demonstrate that our brain-inspired FSF method obtains obvious improvement of detection performance on AIR-SARShip-1.0.</p
AMF-Net: An adaptive multisequence fusing neural network for multi-modality brain tumor diagnosis
No full textTo precisely diagnose the brain tumor types and grades, magnetic resonance imaging (MRI), which is a kind of multisequence imaging technology, is usually applied. However, with the limitations of databases, most current computer-aided brain tumor diagnosis methods employ only a single MRI sequence, and the generalizability of these methods is not ideal. To improve the brain tumor diagnosis performance, an adaptive multisequence fusing neural network (AMF-Net), which can merge the characteristics of different MRI sequences with adaptive weights, is proposed. Inspired by the approximate horizontal symmetry of brains and manual diagnosis process, normalized horizontal differential images are adopted as the spatial attention mechanism, and dense skip connections from T2-weighted (T2-W) sequences are implemented to emphasize the importance of the T2-W sequences. Moreover, to adaptively combine different MRI sequences, an innovative self-learning mechanism, namely adaptive sequence fusion (ASF) module, is proposed. The experimental results show that the average accuracies of the AMF-Net on two databases reach 98.1% and 92.1%, respectively, and the application of the proposed spatial attention mechanism and the ASF module can improve the average accuracy on two databases by 1.7%/1.7% and 1.3%/2.1%, respectively, which indicates that the proposed spatial attention mechanism and the ASF module can improve the performance for brain tumor diagnosis tasks
Research on Air-ground Cooperative Navigation Based on VSLAM
No full text针对机器人同步定位与导航系统中,空中无人机执行地面任务灵活性差、地面无人车视野易被遮挡等问题,采用基于视觉同步定位与地图构建（SLAM）的空地协同导航方法;针对现有空地协同导航系统中无人机多视角下的视差问题,提出了3D-2D线特征匹配方法;针对图像轮廓还原程度较差的问题,将无人机关键帧拼接后的边缘图像与SLAM地图进行基于轮廓相似度的融合。地面无人车通过视觉标靶对自身定位,并融合激光雷达局部地图的方法实时修正地图,完成路径规划。通过仿真进行测试,证明了方案的可行性和方法的有效性。</p
A Quality-Related Fault Detection Method Based on the Dynamic Data-Driven Algorithm for Industrial Systems
No full textFor nearly a decade, quality-related fault detection algorithms have been widely used in industrial systems. However, the majority of these detection strategies rely on static assumptions of the operating environment. In this paper, taking the time series of variables into consideration, a dynamic kernel entropy component regression (DKECR) framework is proposed to address the instability of quality-related fault detection due to the existing dynamic characteristics. Compared with the typical kernel entropy component analysis method, the proposed method constructs the relationship between process states and quality states to further interpret the direct effect on the product taken by the fault. In the proposed approach, process measurements are converted to a lower-dimensional subspace with a specific angular structure that is more comprehensive than traditional subspace approaches. In addition, the angular statistics and their relevant thresholds are exploited to enhance the quality-related fault detection performance. Finally, the proposed method will be compared with three methods by means of a numerical example and two industrial scenarios to demonstrate its practicality and effectiveness.</p
Bubble-based microrobots enable digital assembly of heterogeneous microtissue modules
No full textThe specific spatial distribution of tissue generates a heterogeneous micromechanical environment that provides ideal conditions for diverse functions such as regeneration and angiogenesis. However, to manufacture microscale multicellular heterogeneous tissue modules in vitro and then assemble them into specific functional units is still a challenging task. In this study, a novel method for the digital assembly of heterogeneous microtissue modules is proposed. This technique utilizes the flexibility of digital micromirror device-based optical projection lithography and the manipulability of bubble-based microrobots in a liquid environment. The results indicate that multicellular microstructures can be fabricated by increasing the inlets of the microfluidic chip. Upon altering the exposure time, the Young's modulus of the entire module and different regions of each module can be fine-tuned to mimic normal tissue. The surface morphology, mechanical properties, and internal structure of the constructed bionic peritoneum were similar to those of the real peritoneum. Overall, this work demonstrates the potential of this system to produce and control the posture of modules and simulate peritoneal metastasis using reconfigurable manipulation
Field of experts regularized nonlocal low rank matrix approximation for image denoising
No full textThe restoration of image degraded by noise is an essential preprocessing step for various imaging technologies. Nonlocal low rank matrix approximation has been successfully applied to image denoising due to the capability of recovering the underlying low rank structures. Unfortunately, existing rank minimization models ignore the correlation among image patches and their performance is degraded when encountering the heavy noise. To address this, we propose a field of experts regularized nonlocal low rank matrix approximation (RFoE) denoising model, which integrates a global field of experts (FoE) regularization, a fidelity term, and a nonlocal low rank constraint into a unified framework. The weighted nuclear norm is adopted as the low rank constraint while the FoE prior is utilized to capture the global structure information. An alternating direction minimization algorithm based on half quadratic splitting can effectively solve this model. Extensive experimental results demonstrate that the proposed RFoE model has a superior performance.</p
Burdening optimization of special aluminum alloy with melting loss and storage costs
No full text配料计算是特种铝合金熔炼的重要准备工序，直接影响产品最终性能。为提高产品质量和配料效率，降低原料和仓储物流成本，建立考虑元素烧损和旧料循环利用等因素的特种铝合金配料优化模型。针对该模型的目标多样性和非线性等特点，设计以投料量和投料时间为决策变量的实数编码规则，提出一种基于第III代非支配遗传算法并融入分布式估计策略的多目标优化算法用于求解该模型。通过基于真实生产数据的仿真实验进行模型和算法验证。实验结果表明，该模型能够有效地解决特种铝合金配料优化问题；与传统的多目标优化算法相比，所提出的求解算法能够获得更优的结果。</p
Residual Stress Distribution and Dynamic Stress Variation in Aluminum Alloy Round Rods after Laser Shock Peening
No full textLaser shock peening is an advanced surface treatment technology that can significantly improve the performance of metallic components. To study the residual stress distribution and the propagation law of the dynamic stress in a round rod structure after laser shock peening, a laser shock peening finite element model was established for aluminum alloy round rod fatigue test samples. The residual stress distribution of the sample after laser shock peening with different spot sizes was analyzed in three directions. The propagation law of the dynamic stress was analyzed by a simulation of the dynamic stress change process. The accuracy of the model was experimentally verified. The results showed that as the spot size increased, the range of surface residual stress gradually increased in the axial direction. The degree of residual stress range increase in the circumference direction was smaller than the increase in the axial direction. The convergence of the unloaded tensile stress wave and the reflected tensile stress wave led to the formation of tensile residual stress in the round rod center. The compressive stress generated at the impact edge increased the final compressive residual stress. As the spot size decreased, the fatigue life of the samples increased. These conclusions can not only guide the selection of process parameters for a curved surface structure but also provide a reference for the analysis of the laser-induced shock wave propagation mechanism for specific structures.</p
Amplitude of undulating fin in the vicinity of a wall: Influence of unsteady wall effect on marine propulsion
No full textTo investigate the role of the amplitude of an object under the unsteady wall effect in fluid dynamics, we modelled an undulating fin near a wall in a two-dimensional Cartesian coordinate system. The fin was tethered in a uniform flow and controlled by a user-defined function program. The unsteady wall effect improved the propulsion force and propulsion efficiency at different amplitudes, but the lift force behaved differently. We determined the critical amplitude for the model, below which the lift force is positive within an appropriate off wall distance range. At amplitudes larger than the critical amplitude and as the off-wall distance decreases, the average lift force is, however, always negative, causing the undulating fin to overturn towards the wall and lose stability. The essence of propulsion and lift variation lies in the change in the shape of the space between the wall and the fin, which affects the fluid flow structure and pressure distribution. In addition, some interesting phenomena related to the vortex core arrangement and pressure distribution were introduced at different amplitudes caused by the unsteady wall effect. The present results may provide new insights into the behaviours of benthic fish, reducing their undulating amplitudes and pitch angles near walls
一种全海深载人潜水器控制系统仿真平台
No full text本发明属于潜水器仿真系统领域，具体说是一种全海深载人潜水器控制系统仿真平台，包括：实体单元、虚拟仿真单元以及三维视景单元；实体单元，用于发送操作信号至虚拟仿真单元，同时接收虚拟仿真单元产生的模拟仿真信号；虚拟仿真单元，用于接收并处理实体单元发送的操作信号，对接收到操作信号进行仿真，并对操作信号仿真后得到的仿真运动状态数据进行显示，以对实体单元对应功能进行验证；并将仿真运动状态数据发送至三维视景单元，还产生模拟仿真信号输出至实体单元；本发明的仿真控制电路针对实体单元的每一路接口信号均进行功能性及通断性检测，保证控制系统功能检测的全面性，同时结合电子负载，在仿真平台上对控制系统的真正负载能力测试