In the environment of smart examination rooms, it is important to quickly and accurately detect abnormal behavior(human standing) for the construction of a smart campus. Based on deep learning, we propose an intellige...In the environment of smart examination rooms, it is important to quickly and accurately detect abnormal behavior(human standing) for the construction of a smart campus. Based on deep learning, we propose an intelligentstanding human detection (ISHD) method based on an improved single shot multibox detector to detect thetarget of standing human posture in the scene frame of exam room video surveillance at a specific examinationstage. ISHD combines the MobileNet network in a single shot multibox detector network, improves the posturefeature extractor of a standing person, merges prior knowledge, and introduces transfer learning in the trainingstrategy, which greatly reduces the computation amount, improves the detection accuracy, and reduces the trainingdifficulty. The experiment proves that the model proposed in this paper has a better detection ability for the smalland medium-sized standing human body posture in video test scenes on the EMV-2 dataset.展开更多
Delay Tolerant Network (DTN) is a class of networks that experience frequent and long-duration partitions due to sparse distribution of nodes. It has a broad prospect to new network applications for a better seal...Delay Tolerant Network (DTN) is a class of networks that experience frequent and long-duration partitions due to sparse distribution of nodes. It has a broad prospect to new network applications for a better sealability, fault-tolerant, and high performance. In DTNs, path failure occurs frequently, so message transfer is not reliable. Sometimes it is required to change routing even in a very short period, resulting in transmission delay and reception delay. However, some well-known assumptions of traditional networks are no longer true in DTNs. In this paper, we study the problem of path failures in DTNs. The path failure process in DTNs is described when the path appears completely normal, completely failed and partially failed. Traditional approaches based on using precisely known network dynamics have not accounted for message losses. A new fault tolerant scheme to generate redundancy is to use erasure coding and full replication. This can greatly decrease the path failure rate. At last, a traffic DTN model is analyzed. Results reveal the superiority of our scheme in comparison to other present schemes.展开更多
We propose a new type of dispersion flattening technology, which can generate an ultra-flat group velocity dispersion profile with five and six zero-dispersion wavelengths(ZDWs). The dispersion value varies from-0.15 ...We propose a new type of dispersion flattening technology, which can generate an ultra-flat group velocity dispersion profile with five and six zero-dispersion wavelengths(ZDWs). The dispersion value varies from-0.15 to 0.35 ps/(nm·km) from 4 to 8 μm, which to the best of our knowledge is the flattest one reported so far, and the dispersion flatness is improved by more than an order of magnitude. We explain the principle of producing six ZDWs. Mode distribution in this waveguide is made stable over a wide bandwidth. General guidelines to systematically control the dispersion value, sign, and slope are provided, and one can achieve the desired dispersion by properly adjusting the structural parameters. Fabrication tolerance of this waveguide is also examined.展开更多
基金supported by the Natural Science Foundation of China 62102147National Science Foundation of Hunan Province 2022JJ30424,2022JJ50253,and 2022JJ30275+2 种基金Scientific Research Project of Hunan Provincial Department of Education 21B0616 and 21B0738Hunan University of Arts and Sciences Ph.D.Start-Up Project BSQD02,20BSQD13the Construct Program of Applied Characteristic Discipline in Hunan University of Science and Engineering.
文摘In the environment of smart examination rooms, it is important to quickly and accurately detect abnormal behavior(human standing) for the construction of a smart campus. Based on deep learning, we propose an intelligentstanding human detection (ISHD) method based on an improved single shot multibox detector to detect thetarget of standing human posture in the scene frame of exam room video surveillance at a specific examinationstage. ISHD combines the MobileNet network in a single shot multibox detector network, improves the posturefeature extractor of a standing person, merges prior knowledge, and introduces transfer learning in the trainingstrategy, which greatly reduces the computation amount, improves the detection accuracy, and reduces the trainingdifficulty. The experiment proves that the model proposed in this paper has a better detection ability for the smalland medium-sized standing human body posture in video test scenes on the EMV-2 dataset.
基金National Nature Science Foundation of China (No.60534020)Cultivation Fund of the Key Scientific and Technical Innovation Project from Ministry of Education of China(No.706024)+1 种基金International Science Cooperation Foundation of Shanghai,China(No.061307041)Shanghai Talent Developing Foundation,China(No.010)
文摘Delay Tolerant Network (DTN) is a class of networks that experience frequent and long-duration partitions due to sparse distribution of nodes. It has a broad prospect to new network applications for a better sealability, fault-tolerant, and high performance. In DTNs, path failure occurs frequently, so message transfer is not reliable. Sometimes it is required to change routing even in a very short period, resulting in transmission delay and reception delay. However, some well-known assumptions of traditional networks are no longer true in DTNs. In this paper, we study the problem of path failures in DTNs. The path failure process in DTNs is described when the path appears completely normal, completely failed and partially failed. Traditional approaches based on using precisely known network dynamics have not accounted for message losses. A new fault tolerant scheme to generate redundancy is to use erasure coding and full replication. This can greatly decrease the path failure rate. At last, a traffic DTN model is analyzed. Results reveal the superiority of our scheme in comparison to other present schemes.
基金National Natural Science Foundation of China(61775164,61225005,61775165)
文摘We propose a new type of dispersion flattening technology, which can generate an ultra-flat group velocity dispersion profile with five and six zero-dispersion wavelengths(ZDWs). The dispersion value varies from-0.15 to 0.35 ps/(nm·km) from 4 to 8 μm, which to the best of our knowledge is the flattest one reported so far, and the dispersion flatness is improved by more than an order of magnitude. We explain the principle of producing six ZDWs. Mode distribution in this waveguide is made stable over a wide bandwidth. General guidelines to systematically control the dispersion value, sign, and slope are provided, and one can achieve the desired dispersion by properly adjusting the structural parameters. Fabrication tolerance of this waveguide is also examined.