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Upper bounds on the capacity for optical intensity channels with AWGN

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Science China(Information Sciences) 2017年第2期60卷 165-176页

作者： Yingying YU Zaichen ZHANG Liang WU jian dang National Mobile Communications Research Laboratory Southeast University

The channel capacity of the optical wireless communication(OWC) systems is still a problem that has not an optimal and close-form expression, in spite of OWC can be used to achieve high data rates. This paper presents novel upper bounds on the channel capacity of an optical intensity modulated and directed detection(IM/DD) system under peak-power and average-power constraints. The channel is modeled as an additive white Gaussian noise(AWGN) optical channel. The bounds are derived based on sphere-based signal space argument. Simulation results show the proposed bounds are tight at both high and low signal-to-noise ratios(SNRs). Compared to those reported bounds, the derived bounds are better at high SNRs region in particular, and the expressions are simpler and unique for the whole range of average-to-peak-power ratio.

关键词： channel capacity optical communication AWGN sphere-based signal space high signal-to-noise ratios(SNRs)

Enhanced Power Choice Barring Scheme For Massive MTCs With Grant-Free NOMA

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China Communications 2021年第10期18卷 135-147页

作者： Liang Wu Xiaorui Tang Zaichen Zhang jian dang National Mobile Communications Research Laboratory Southeast UniversityNanjing 210096China Purple Mountain Laboratories Nanjing 211111China

Massive machine-type communication(m MTC)is a typical application scenario of the fifth generation(5G)mobile *** keep the m MTC reliable and minimize the energy consumption of the m MTC devices,this paper proposes an enhanced power choice barring(EPCB)scheme based on the distributed layered grant-free non-orthogonal multiple access(NOMA)framework,where the cell is divided into different layers according to a predetermined power *** proposed EPCB scheme not only combines the grant-free strategy with the sleep mode to reduce the energy consumption,but also designs a power level choosing strategy to increase the access success *** results show that when compared with existing schemes,the proposed EPCB scheme has better performance in the aspects of the access success probability and energy efficiency.

关键词： grant-free massive machine-type communication NOMA power level choosing

Fast Single-phase Fault Location Method Based on Community Graph Depth-first Traversal for Distribution Network

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CSEE Journal of Power and Energy Systems 2023年第2期9卷 612-622页

作者： jian dang Yunjiang Yan Rong Jia Xiaowei Wang Hui Wei Xi’an Key Laboratory of Intelligent Energy Xi’an University of TechnologyShaanxi 710048China

With the increasing complexity of distribution network structures originating from the high penetration of renewable energy and responsive loads,fast and accurate fault location technology for distribution networks is a prerequisite for rapid isolation of faults and restoration of the power *** this paper,a fault location method based on community graph depth-first traversal is proposed for fast location of single-phase ground faults in distribution ***,this paper defines the fault graph weight of the vertices in the distribution network graph model,which can be used to reflect the topology of the vertices and fault points as well as the fluctuation of the vertices’***,the vertices on the graph model are clustered by using an improved parallel louvain method(IPLM).Finally,the community formed by IPLM is used as the smallest unit for depth-first traversal to achieve fast and accurate location of the fault *** paper develops a distribution network graph model of IEEE 33-bus system on the graph database for *** three other methods are selected for comparison with *** test results show that IPLMDF can achieve fast and accurate fault location when half of the nodes in the distribution network are equipped with *** some of the D-PMUs lose time synchronization,it is still possible to locate the fault section,and at the same time,the locating results can be avoided by falling into local optimal solutions.

关键词： Depth-first traversal fault location graph computation single-phase fault

Fault Information Recognition for On-board Equipment of High-speed Railway Based on Multi-neural Network Collaboration

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International Journal of Automation and computing 2021年第6期18卷 935-946页

作者： Lu-Jie Zhou jian-Wu dang Zhen-Hai Zhang School of Automation and Electrical Engineering Lanzhou Jiaotong UniversityLanzhou 730070China Gansu Provincial Engineering Research Center for Artificial Intelligence and Graphic&Image Processing Lanzhou 730070China

It is of great significance to guarantee the efficient statistics of high-speed railway on-board equipment fault information,which also improves the efficiency of fault analysis. Considering this background, this paper presents an empirical exploration of named entity recognition(NER) of on-board equipment fault information. Based on the historical fault records of on-board equipment, a fault information recognition model based on multi-neural network collaboration is proposed. First, considering Chinese recorded data characteristics, a method of constructing semantic features and additional features based on character granularity is proposed. Then, the two feature representations are concatenated and passed into the gated convolutional layer to extract the dependencies from multiple different subspaces and adjacent characters in parallel. Next, the local features are transmitted to the bidirectional long short-term memory(BiLSTM) to learn long-term dependency information. On top of BiLSTM, the sequential conditional random field(CRF) is used to jointly decode the optimized tag sequence of the whole sentence. The model is tested and compared with other representative baseline models. The results show that the proposed model not only considers the language characteristics of on-board fault records, but also has obvious advantages on the performance of fault information recognition.

关键词： Train control system Chinese named entity recognition(NER) character feature gating mechanism bidirectional long short-term memory(BiLSTM)

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Fault Classification for On-board Equipment of High-speed Railway Based on Attention Capsule Network

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International Journal of Automation and computing 2021年第5期18卷 814-825页

The conventional troubleshooting methods for high-speed railway on-board equipment, with over-reliance on personnel experience, is characterized by one-sidedness and low efficiency. In the process of high-speed train operation, numerous text-based onboard logs are recorded by on-board computers. Machine learning methods can help technicians make a correct judgment of fault types using the on-board log reasonably. Therefore, a fault classification model of on-board equipment based on attention capsule networks is proposed. This paper presents an empirical exploration of the application of a capsule network with dynamic routing in fault classification. A capsule network can encode the internal spatial part-whole relationship between various entities to identify the fault types. As the importance of each word in the on-board log and the dependencies between them have a significant impact on fault classification, an attention mechanism is incorporated into the capsule network to distill important information. Considering the imbalanced distribution of normal data and fault data in the on-board log, the focal loss function is introduced into the model to adjust the imbalanced data. The experiments are conducted on the on-board log of a railway bureau and compared with other baseline models. The experimental results demonstrate that our model outperforms the compared baseline methods, proving the superiority and competitiveness of our model.

关键词： On-board equipment fault classification capsule network attention mechanism focal loss

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Effect of Counterface Material on Friction and Wear Behavior of Ni-Cr-W-Al-Ti-MoS_2 Composites

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Chinese Journal of Aeronautics 2006年第B12期19卷 74-77页

作者： LI jian-liang XIONG dang-sheng WAN Yi Department of Materials Science and Engineering Nanfing University of Science and Technology Nanjing 210094 China

Ni-Cr-W-Al-Ti-MoS2 self-lubricating composites were prepared through the powder metallurgy （P/M） method. Their friction properties were investigated by a pin-on-disk tribometer in the range from the room temperature to 600 ℃. Alumina, silicon nitride and nickel-iron-sulfide alloys were selected as the counterface materials. Results indicate that the lowest friction coefficients under 0.22 can be obtained at 600℃ when rubbed against alumina. When rubbed against nickel-iron-sulfide alloys, are presented the lowest wear rates in the magnitude of 10^-6 mm^3/N-m, one order of magnitude lower than those when rubbed against ceramics. In the case of three rubbing pairs, the wear rates of the composite containing MoS2 present themselves inversely proportional to friction coefficients. With alumina ceramics used as a counterface, transfer films and glaze layers will form on the contact surface playing a main role in lubrication at high temperatures. However, when silicon nitride and nickel-iron-sulfide alloy are used, the lubricating transfer films appear not to be prominent.

关键词： powder metallurgy (P/M) high temperature solid lubrication Ni-based composite

Clinical characteristics of coronavirus disease 2019 in patients aged 80 years and older

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Journal of Integrative Medicine 2020年第5期18卷 395-400页

作者： jian-zhong dang Gang yan Zhu Ying jie Yang Fang Zheng Department of Critris Renrmin Haspital of Wuhan UniversilyWuhan 430060Hubei ProvinceChina Departmemt of Peiarics.Union Hospital.Tongi Medical Cllege.Huazhong Univrsity of Science and Technology.Wuhan 430022 Hubei Province China

Objective: Coronavirus disease 2019(COVID-19) has raised concern around the world as an epidemic or pandemic. As data on COVID-19 has grown, it has become clear that older adults have a disproportionately high rate of death from COVID-19. This study describes the early clinical characteristics of COVID-19 in patients with more than 80 years of ***: Epidemiological, clinical, laboratory, radiological, and treatment data from 17 patients diagnosed with COVID-19 between January 20 and February 20, 2020 were collected and analyzed retrospectively. Treatment outcomes among subgroups of patients with non-severe and severe symptoms of COVID-19 were ***: Of the 17 hospitalized patients with COVID-19, the median age was 88.0 years(interquartile range, 86.6–90.0 years;range, 80.0–100.0 years) and 12(70.6%) were men. The age distribution of patients was not significantly different between non-severe group and severe group. All patients had chronic pre-existing conditions. Hypertension and cardiovascular diseases were the most common chronic conditions in both subgroups. The most common symptoms at the onset of COVID-19 were fever(n = 13;76.5%), fatigue(n = 11;64.7%), and cough(n = 5;29.4%). Lymphopenia was observed in all patients, and lymphopenia was significantly more severe in the severe group than that in non-severe group(0.4×10~9/L vs 1.2×10~9/L, P = 0.014). The level of serum creatinine was higher in the severe group than in the non-severe group(99.0 lmol/L vs 62.5 lmol/L, P = 0.038). The most common features of chest computed tomography images were nodular foci in 10(58.8%) patients and pleural thickening in 7(41.2%) patients. All patients received antiviral therapy, while some patients also received intravenous antibiotics therapy(76.5%), Chinese medicinal preparation therapy(Lianhuaqingwen capsule, 64.7%), corticosteroids(35.3%) or immunoglobin(29.4%). Eight patients(47.1%) were transferred to the intensive care unit because of complications. Ten

关键词： Coronavirus 2019-nCoV SARS-CoV-2 COVID-19 Older patients

Vector Approximate Message Passing with Sparse Bayesian Learning for Gaussian Mixture Prior

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China Communications 2023年第5期20卷 57-69页

作者： Chengyao Ruan Zaichen Zhang Hao jiang jian dang Liang Wu Hongming Zhang National Mobile Communications Research Laboratory Frontiers Science Center for Mobile Information Communication and SecuritySoutheast UniversityNanjing 210096China Purple Mountain Laboratories No.9 Mozhou East RoadNanjing 211111China School of Artificial Intelligence Nanjing University of Information Science and TechnologyNanjing 210044China School of Information and Communication Engineering Beijing University of Posts and TelecommunicationsBeijing 100876China

Compressed sensing(CS)aims for seeking appropriate algorithms to recover a sparse vector from noisy linear ***,various Bayesian-based algorithms such as sparse Bayesian learning(SBL)and approximate message passing(AMP)based algorithms have been *** SBL,it has accurate performance with robustness while its computational complexity is high due to matrix *** AMP,its performance is guaranteed by the severe restriction of the measurement matrix,which limits its application in solving CS *** overcome the drawbacks of the above algorithms,in this paper,we present a low complexity algorithm for the single linear model that incorporates the vector AMP(VAMP)into the SBL structure with expectation maximization(EM).Specifically,we apply the variance auto-tuning into the VAMP to implement the E step in SBL,which decrease the iterations that require to converge compared with VAMP-EM algorithm when using a Gaussian mixture(GM)*** results show that the proposed algorithm has better performance with high robustness under various cases of difficult measurement matrices.

关键词： sparse Bayesian learning approximate message passing compressed sensing expectation propagation

Carbamylated Erythropoietin Alleviates Kidney Damage in Diabetic Rats by Suppressing Oxidative Stress

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Current Medical Science 2021年第3期41卷 513-521页

作者： jian-zhong dang Ya-fang TU Juan WANG Ying-jie YANG Department of Geriatrics Rerunin Hospital of Wuhan UniversityWuhan 430060China Department of Nephrology Renmin Hospital of Wuhan UniversityWuhan 430060China

The oxidative stress response plays an important role in the occurrence and development of diabetic kidney disease(DKD).It has become a new treatment target for *** the current study,the effects of carbamylated erythropoietin(CEPO)on renal oxidative stress and damage in diabetic rats were *** Sprague Dawley rats were intraperitoneally administered with 60 mg/kg streptozotocin to establish the diabetes *** diabetic rats were randomly allocated into 4 groups(n=6 each):diabetes model group(DM group),DM+CEPO treatment group(DC group),DM+CEPO+EPO receptor(EPOR)blocking peptide treatment group(DCEB group),and DM+CEPO+CD131 blocking peptide treatment group(DCCB group).Meanwhile,a normal control group(NC group,n=6)was set *** tissues and blood samples were obtained for evaluation of oxidative stress and renal *** results showed that diabetic rats exhibited increased oxidative stress in the kidney and early pathological changes associated with *** with CEPO reduced oxidative stress and attenuated renal ***,diabetic rats treated with the combination of CEPO and EPOR blocking peptide or CD131 blocking peptide showed increased oxidative stress and reduced renal function when compared with CEPO treatment alone *** results suggested that CEPO can protect against kidney damage in DKD by inhibiting oxidative stress injury via EPOR-CD131 heterodimers.

关键词： diabetic kidney disease oxidative stress carbamylated erythropoietin erythropoietin receptor