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Efficient cutting path planning for a non-spherical tool based on an iso-scallop height distance field

Chinese Journal of Aeronautics 2024年第7期37卷 496-510页

作者： Jiancheng HAO Dong HE Zhaoyu LI Pengcheng HU Yuanzhi CHEN Kai TANG Department of Mechanical and aerospace Engineering Hong Kong University of Science and TechnologyHong Kong 999077China The Hong Kong University of Science and Technology(Guangzhou) Smart Manufacturing ThrustNanshaGuangzhou 511400China HKUST Shenzhen-Hong Kong Collaborative innovation Research institute Shenzhen 518057China HKUST Shenzhen Research institute Shenzhen 518057China

Iso-scallop height machining means,when machining a freeform surface,the scallop height between any two neighboring tool paths on the surface will be a constant(i.e.,the given threshold),which is preferable among various freeform surface machining strategies due to its high machining efficiency as well as better machine tool’s ***,all the existing iso-scallop height path planning methods pertain to only the ball-end or flat-end types of *** recent years,the non-spherical cutting tool has become more and more popular,especially for five-axis machining of complex freeform surfaces,majorly owing to its non-constant curvature which can be utilized to adaptively fit the tool to the surface to both avoid the local gouging and enlarge the cutting ***,there have been no reported works on iso-scallop height five-axis tool path generation for a non-spherical tool,and,in this paper,we present ***,we first define and construct two fields on the surface to be machined-the collision-free tool orientation field(vector)and the iso-scallop height distance field(scalar).The iso-lines of the scalar field and their associated tool orientation field vectors then naturally serve as potential iso-scallop height five-axis tool paths,and we present a propagation-based algorithm to construct the desired tool path from the *** computer simulation and physical cutting experiments confirm that everywhere on the surface,except maybe near the saddle curves of the scalar filed,the scallop height is exactly the given *** adding the saddle curves as extra tool paths,the final machined surface then is assured of the required scallop height requirement.

关键词： Freeform surface machining Iso-scallop tool path Customized tool Five-axis tool path Computer aided manufacturing

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Low-rank matrix recovery with total generalized variation for defending adversarial examples

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Frontiers of information Technology & Electronic Engineering 2024年第3期25卷 432-445页

作者： Wen LI Hengyou WANG Lianzhi HUO Qiang HE Linlin CHEN Zhiquan HE Wing W.Y.Ng School of Science Beijing University of Civil Engineering and ArchitectureBeijing 100044China School of Computer Science and Engineering South China University of TechnologyGuangzhou 510006China aerospace information Research institute Chinese Academy of SciencesBeijing 100094China Guangdong Key Laboratory of Intelligent information Processing Shenzhen 518060China institute of Big Data Modeling and Technology Beijing University of Civil Engineering and ArchitectureBeijing 100044China

Low-rank matrix decomposition with first-order total variation(TV)regularization exhibits excellent performance in exploration of image *** advantage of its excellent performance in image denoising,we apply it to improve the robustness of deep neural ***,although TV regularization can improve the robustness of the model,it reduces the accuracy of normal samples due to its *** our work,we develop a new low-rank matrix recovery model,called LRTGV,which incorporates total generalized variation(TGV)regularization into the reweighted low-rank matrix recovery *** the proposed model,TGV is used to better reconstruct texture information without *** reweighted nuclear norm and Li-norm can enhance the global structure ***,the proposed LRTGV can destroy the structure of adversarial noise while re-enhancing the global structure and local texture of the *** solve the challenging optimal model issue,we propose an algorithm based on the alternating direction method of *** results show that the proposed algorithm has a certain defense capability against black-box attacks,and outperforms state-of-the-art low-rank matrix recovery methods in image restoration.

关键词： Total generalized variation Low-rank matrix Alternating direction method of multipliers Adversarial example

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High-performance,low-power,and flexible ultraviolet photodetector based on crossed ZnO microwires p-n homojunction

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Photonics Research 2024年第4期12卷 648-662页

作者： SHULIN SHA KAI TANG MAOSHENG LIU PENG WAN CHENYANG ZHU DANING SHI CAIXIA KAN MINGMING JIANG College of Physics MIIT Key Laboratory of Aerospace Information Materials and PhysicsKey Laboratory for Intelligent Nano Materials and DevicesNanjing University of Aeronautics and AstronauticsNanjing 211106China

Low-power, flexible, and integrated photodetectors have attracted increasing attention due to their potential applications of photosensing, astronomy, communications, wearable electronics, etc. Herein, the samples of ZnO microwires having p-type(Sb-doped ZnO, ZnO:Sb) and n-type(Ga-doped ZnO, ZnO:Ga) conduction properties were synthesized individually. Sequentially, a p-n homojunction vertical structure photodiode involving a single ZnO:Sb microwire crossed with a ZnO:Ga microwire, which can detect ultraviolet light signals, was constructed.

关键词： power ultraviolet conduction

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Synaptic a-Si:H/a-Ga_(2)O_(3)phototransistor inspired by the phototaxis behavior of organisms with all-optical and all-electrical stimulation modes

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Nano Research 2024年第8期17卷 7631-7642页

作者： Youngbin Yoon Youngki Kim Soowon Choi Jungdae Kwon Myunghun Shin School of Electronics and information Engineering Korea Aerospace UniversityGoyang10540Republic of Korea Nano Materials Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea Department of Materials Science and Engineering Pusan National UniversityBusan 46241Republic of Korea

To improve neuromorphic computing performance,neuromorphic system components should mimic the behaviors of organic *** this study,a synaptic a-Si:H/a-Ga_(2)O_(3)phototransistor featuring all-optical and-electrical emulation is fabricated in a manner advantageous for complementary metal-oxide-semiconductor process *** phototransistor exhibits excitatory and inhibitory synaptic behaviors under stimulation by both optical and electrical *** mimics several essential synaptic functions,including excitatory postsynaptic current,inhibitory postsynaptic current,short-term memory,long-term memory,pairedpulse facilitation,and spike-timing-dependent *** optical and electrical modulation mechanisms are confirmed to arise from the a-Si:H/a-Ga_(2)O_(3)heterojunction structure and interface effects,and the device is shown to operate at low power in both optical and electrical *** all-optical weight modulation function is applied to the wavelength-differential behavior response of zebrafish,successfully mimicking the color perception process of the ***,to verify the translation of the optoelectrical-derived synaptic behaviors of the phototransistor into artificial neuromorphic computation,handwritten digit image recognition of the Modified National institute of Standards and Technology dataset is performed by a convolutional neural network,with a demonstrated average learning accuracy of 98.46%.These findings verify the applicability of the synaptic a-Si:H/a-Ga_(2)O_(3)phototransistor in neuromorphic computing.

关键词： synaptic phototransistor artificial synapse phototaxis neuromorphic computing interface charge state optoelectronic synaptic device

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Bioinspired Closed-loop CPG-based Control of a Robotic Manta for Autonomous Swimming

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Journal of Bionic Engineering 2024年第1期21卷 177-191页

作者： Yiwei Hao Yonghui Cao Yingzhuo Cao Xiong Mo Qiaogao Huang Lei Gong Guang Pan Yong Cao School of Marine Science and Technology Northwestern Polytechnical UniversityXi'an 710072China Unmanned Vehicle innovation Center Ningbo Institute of NPUNingbo 315103China Key Laboratory of Unmanned Underwater Vehicle Technology of Ministry of Industry and information Technology Xi'an 710072China

Fish in nature exhibit a variety of swimming modes such as forward swimming,backward swimming,turning,pitching,etc.,enabling them to swim in complex scenes such as coral *** is still difficult for a robotic fish to swim autonomously in a confined area as a real ***,we develop an untethered robotic manta as an experimental platform,which consists of two flexible pectoral fins and a tail fin,with three infrared sensors installed on the front,left,and right sides of the head to sense the surrounding *** generate multiple swimming modes of the robotic manta and online switching of different modes,we design a closed-loop Central Pattern Generator(CPG)controller based on distance information and use a combination of phase difference and amplitude of the CPG model to achieve stable and rapid adjustment of yaw *** verify the autonomous swimming ability of the robotic manta in complex scenes,we design an experimental scenario with a concave *** experimental results show that the robotic manta can achieve forward swimming,backward swimming,in situ turning within the concave obstacle,and finally exit from the area safely while relying on the perception of external obstacles,which can provide insight into the autonomous exploration of complex scenes by the biomimetic robotic ***,the swimming ability of the robotic manta is verified by field tests.

关键词： Biomimetic robotic manta Central Pattern Generator Closed-loop control Backward swimming

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Ultra-high sensitivity fiber optic microphone with corrugated graphene-oxide diaphragm for voice recognition

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Nano Research 2024年第8期17卷 7593-7602页

作者： Yang Liu Cheng Li Lingxiao Yu Zhengwei Wu Shangchun Fan Ruitao Lv School of Instrumentation and Optoelectronic Engineering Beihang UniversityBeijing 100191China Shenzhen institute of Beihang University Shenzhen 518063China Key Laboratory of Advanced Materials(MOE) School of Materials Science and EngineeringTsinghua UniversityBeijing 100084China aerospace information Research institute Chinese Academy of SciencesBeijing 100190China

To avoid interference from unexpected background noises and obtain high fidelity voice signal,acoustic sensors with high sensitivity,flat frequency response,and high signal-to-noise ratio(SNR)are urgently needed for voice ***(GO)has received extensive attention due to its advantages of controllable thickness and high fracture ***,low mechanical sensitivity(SM)introduced by undesirable initial stress limits the performance of GO material in the field of voice *** alleviate the aforementioned issue,GO diaphragm with annular corrugations is *** means of the reusable copper mold machined by picosecond laser,the fabrication and transfer of corrugated GO diaphragm are realized,thus achieving a Fabry–Perot(F–P)acoustic *** from the structural advantage of the corrugated GO diaphragm,our F–P acoustic sensor exhibits high S_(M)(43.70 nm/Pa@17 kHz),flat frequency response(−3.2 to 3.7 dB within 300–3500 Hz),and high SNR(76.66 dB@1 kHz).In addition,further acoustic measurements also demonstrate other merits,including an excellent frequency detection resolution(0.01 Hz)and high time stability(output relative variation less than 6.7%for 90 min).Given the merits presented before,the fabricated F–P acoustic sensor with corrugated GO diaphragm can serve as a high-fidelity platform for acoustic detection and voice *** conjunction with the deep residual learning framework,high recognition accuracy of 98.4%is achieved by training and testing the data recorded by the fabricated F–P acoustic sensor.

关键词： corrugated graphene-oxide(GO)diaphragm Fabry-Perot(F-P)acoustic sensor mechanical sensitivity voice recognition

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Development of Spectral Features for Monitoring Rice Bacterial Leaf Blight Disease Using Broad-Band Remote Sensing Systems

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Phyton-International Journal of Experimental Botany 2024年第4期93卷 745-762页

作者： Jingcheng Zhang Xingjian Zhou Dong Shen Qimeng Yu Lin Yuan Yingying Dong College of Artificial Intelligence Hangzhou Dianzi UniversityHangzhou310018China School of information Engineering Zhejiang University of Water Resources and Electric PowerHangzhou310018China Key Laboratory of Digital Earth Science Aerospace Information Research InstituteChinese Academy of SciencesBeijing100094China

As an important rice disease, rice bacterial leaf blight (RBLB, caused by the bacterium Xanthomonas oryzae ***), has become widespread in east China in recent years. Significant losses in rice yield occurred as a result ofthe disease’s epidemic, making it imperative to monitor RBLB at a large scale. With the development of remotesensing technology, the broad-band sensors equipped with red-edge channels over multiple spatial resolutionsoffer numerous available data for large-scale monitoring of rice diseases. However, RBLB is characterized by rapiddispersal under suitable conditions, making it difficult to track the disease at a regional scale with a single sensorin practice. Therefore, it is necessary to identify or construct features that are effective across different sensors formonitoring RBLB. To achieve this goal, the spectral response of RBLB was first analyzed based on the canopyhyperspectral data. Using the relative spectral response (RSR) functions of four representative satellite or UAVsensors (i.e., Sentinel-2, GF-6, Planet, and Rededge-M) and the hyperspectral data, the corresponding broad-bandspectral data was simulated. According to a thorough band combination and sensitivity analysis, two novel spectralindices for monitoring RBLB that can be effective across multiple sensors (i.e., RBBRI and RBBDI) weredeveloped. An optimal feature set that includes the two novel indices and a classical vegetation index was *** capability of such a feature set in monitoring RBLB was assessed via FLDA and SVM algorithms. The resultdemonstrated that both constructed novel indices exhibited high sensitivity to the disease across multiple ***, the feature set yielded an overall accuracy above 90% for all sensors, which indicates its cross-sensorgenerality in monitoring RBLB. The outcome of this research permits disease monitoring with different remotesensing data over a large scale.

关键词： Rice bacterial leaf blight analysis of spectral response multispectral data simulation vegetation indices cross-sensor disease monitoring

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Layered Coded Cache Placement and Cooperative Delivery with Sharing Links in Satellite-Terrestrial Integrated Networks

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China Communications 2024年第3期21卷 217-229页

作者： Gu Shushi Chen Zihan Wu Yaonan Zhang Qinyu Wang Ye School of Electronic and information Engineering Harbin Institute of Technology(Shenzhen)Shenzhen 518055China Guangdong Provincial Key Laboratory of aerospace Communication and Networking Technology Shenzhen 518055China Broadband Communications Research Department Pengcheng LaboratoryShenzhen 518052China

Cooperative utilization of multidimensional resources including cache, power and spectrum in satellite-terrestrial integrated networks(STINs) can provide a feasible approach for massive streaming media content delivery over the seamless global coverage area. However, the on-board supportable resources of a single satellite are extremely limited and lack of interaction with others. In this paper, we design a network model with two-layered cache deployment, i.e., satellite layer and ground base station layer, and two types of sharing links, i.e., terrestrial-satellite sharing(TSS) links and inter-satellite sharing(ISS) links, to enhance the capability of cooperative delivery over STINs. Thus, we use rateless codes for the content divided-packet transmission, and derive the total energy efficiency(EE) in the whole transmission procedure, which is defined as the ratio of traffic offloading and energy consumption. We formulate two optimization problems about maximizing EE in different sharing scenarios(only TSS and TSS-ISS),and propose two optimized algorithms to obtain the optimal content placement matrixes, *** results demonstrate that, enabling sharing links with optimized cache placement have more than 2 times improvement of EE performance than other traditional placement schemes. Particularly, TSS-ISS schemes have the higher EE performance than only TSS schemes under the conditions of enough number of satellites and smaller inter-satellite distances.

关键词： coded content placement cooperative delivery energy efficiency sharing links STINs

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A path planning algorithm for a crop monitoring fixed-wing unmanned aerial system

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Science China(information Sciences) 2024年第8期67卷 5-23页

作者： Longhao QIAN Yi Lok LO Hugh Hong-tao LIU institute of aerospace Studies University of Toronto Department of Mechanical Engineering The University of Hong Kong

With the growing demand for automation in agriculture, industries increasingly rely on drones to perform crop monitoring and surveillance. In this regard, fixed-wing unmanned aerial systems(UASs)are viable platforms for scanning a large crop field, given their payload capacity and range. To achieve maximum coverage without landing for battery replacement, an algorithm for producing a minimal required energy survey path is essential. Hence, an energy-aware coverage path planning algorithm is proposed *** constraints for a fixed-wing UAS to fly at low altitudes while achieving full coverage of the crop field are first analyzed. Then, the full path is decomposed into straight-line and U-turn primitives. Finally, an algorithm to calculate a combination of straight-line segments and U-turns is proposed to obtain the path with minimum required energy consumption. The genetic algorithm is used to efficiently determine the order of the straight-line paths to traverse. Case studies show that the proposed algorithm can produce planning results for a convex-polygon-shaped crop field.

关键词： aerial survey energy minimization fixed-wing UAS genetic algorithm path planning

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Recorded recurrent deep reinforcement learning guidance laws for intercepting endoatmospheric maneuvering missiles

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Defence Technology（防务技术） 2024年第1期31卷 457-470页

作者： Xiaoqi Qiu Peng Lai Changsheng Gao Wuxing Jing Department of aerospace Engineering Harbin Institute of TechnologyHarbin150001China Shanghai Electro-Mechanical Engineering institute Shanghai Academy of Spaceflight TechnologyShanghai201100China

This work proposes a recorded recurrent twin delayed deep deterministic(RRTD3)policy gradient algorithm to solve the challenge of constructing guidance laws for intercepting endoatmospheric maneuvering missiles with uncertainties and observation *** attack-defense engagement scenario is modeled as a partially observable Markov decision process(POMDP).Given the benefits of recurrent neural networks(RNNs)in processing sequence information,an RNN layer is incorporated into the agent’s policy network to alleviate the bottleneck of traditional deep reinforcement learning methods while dealing with *** measurements from the interceptor’s seeker during each guidance cycle are combined into one sequence as the input to the policy network since the detection frequency of an interceptor is usually higher than its guidance *** training,the hidden states of the RNN layer in the policy network are recorded to overcome the partially observable problem that this RNN layer causes inside the *** training curves show that the proposed RRTD3 successfully enhances data efficiency,training speed,and training *** test results confirm the advantages of the RRTD3-based guidance laws over some conventional guidance laws.

关键词： Endoatmospheric interception Missile guidance Reinforcement learning Markov decision process Recurrent neural networks

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