基于GAIN-LSTM网络的雷达PRI序列还原及识别方法

开展脉冲重复间隔(Pulse Repetition Interval,PRI)模式识别工作是电子支援系统的一项重要任务。现代复杂电磁环境下,受雷达辐射源部署和接收设备本身影响,雷达脉冲丢失率极高,导致分选后PRI序列调制规律被破坏,现有的PRI模式识别方法准确率不足。针对上述问题,从PRI序列还原角度出发,并结合PRI序列本质是时序序列的特点,提出GAIN-LSTM(Generative Adversarial Imputation Nets and Long Short Term Memory)网络架构,其先对丢失脉冲位置进行补全操作,恢复PRI调制规律,然后对还原后PRI序列进行调制模式识别。仿真结果表明,提出的GAIN-LSTM网络架构在脉冲丢失率70%时仍保持95%的正确识别率。

基于改进模板匹配的多跳频信号参数估计

为解决复杂环境下,同一频段、同一采样时间内多跳频信号分离困难与特征参数估计精度较低的问题,提出了一种改进模板匹配算法。首先,根据干扰信号和噪声的时频特征进行滤波。然后,采用K-means算法对连通域进行预分类,对于可能存在跳频信号混叠的连通域,由跳频信号簇生成相应的模板并进行改进模板匹配,将成功分离的跳频信号归类入相应的簇。最后,对每一个簇的跳频信号参数进行估计,并通过最小二乘法进行修正。实验结果表明,与连通域标记算法相比,所提方法在信噪比高于-3 dB的情况下,平均相对误差低于0.01,鲁棒性较好,有较高的工程价值。

Nonlinear coupling modeling and dynamics analysis of rotating flexible beams with stretching deformation effect

Dynamic coupling modeling and analysis of rotating beams based on the nonlinear Green-Lagrangian strain are introduced in this work.With the reservation of the axial nonlinear strain,there are more coupling terms for axial and transverse deformations.The discretized dynamic governing equations are obtained by using the finite element method and Lagrange’s equations of the second kind.Time responses are conducted to compare the proposed model with other previous models.The stretching deformation due to rotating motion is observed and calculated by special formulations under dynamic equilibrium.The stretching deformation and the change of the associated equilibrium position are taken into account to analyze the free vibration and frequency response of the rotating beams.Analytical and numerical comparisons show that the proposed model can provide reliable results,while the previous models may lead to imprecise results,especially in high-speed conditions.

融合北斗技术的铁路工程线铺轨施工安全管理关键技术

针对铁路长大深埋隧道群工程,研究工程线铺轨施工安全预警关键技术。介绍铺轨施工安全管控总体需求、关键技术、技术创新点、试点及应用情况。融合北斗技术研发长大深埋隧道群内外通信组网、车辆及人员实时定位、终端报警装备、调度指挥中心监控系统,实现车车、车人接近预警,运用技防手段有效降低碰撞发生风险。成套技术采用先试点后推广方式应用于成昆铁路峨冕段铺轨工程,与管理手段相结合,保障工程线铺轨施工安全。

成渝地区双城经济圈发展水平分析与提升对策

成渝地区双城经济圈作为西部地区的重要发展引擎,对西部地区乃至全国都具有重要意义。文章选取2020-2021年成渝地区双城经济圈16个城市的面板数据,通过构建评价指标体系,运用熵值法,全面客观评价成渝地区双城经济圈建设成效。结果显示:两年来,成渝地区双城经济圈综合发展水平不断提升,城市经济联系更加活跃,具有全国影响力的重要经济中心、科技创新中心、改革开放新高地、高品质生活宜居地建设不断夯实,但与长三角、粤港澳大湾区和京津冀城市群相比,还有提升空间。最后,文章提出从构建跨区域产业生态圈、打造协同创新共同体、携手共促改革开放、合力提升生活宜居水平等方面推动成渝地区双城经济圈建设迈向更高能级。

成渝地区双城经济圈创新网络演变及优化策略

建设创新网络是推动成渝地区加快建设科技创新中心的重要手段。文章以成渝地区双城经济圈16个城市2006—2020年合作发明专利为原始数据,利用核心边缘模型、块模型等方法,分析成渝地区双城经济圈城市间创新网络结构,研判城市创新模式。结果表明:成渝地区双城经济圈城市间创新网络核心边缘结构明显,网络权力高度集中于成都,不平衡现象突出,但在逐渐改善;研究期间,成渝地区双城经济圈城市本地创新合作不断增多但总体仍不强,跨界创新联系增长迅速,但“双核独大,中部塌陷”现象突出;网络视角下,成渝地区双城经济圈绝大部分城市创新模式属于内向型创新,获取外部异质性知识困难,存在创新锁定的风险。根据研究结论,对优化成渝地区双城经济圈创新网络提出相关建议。

飞机移动装配线——脉动与续动

针对飞机总装生产过程的保质量、提速度、降成本、增效益的迫切需要,查阅了国内外有关飞机整机及其关键部件装配线的大量文献资料,分析总结了脉动线和续动线的特性及其国内外应用情况,归纳综述了移动装配线在优化规划设计、装配工序平衡优化调度、物料供应优化管理、装配线智能管控等方面的研究现状,分析建立了移动装配线分析设计的霍尔三维模型,综合提出了移动装配线研究开发的几个建议;最后通过典型飞机移动线案例计算分析,对比了脉动装配线和续动装配线的装配效能,验证了续动线比脉动线具有更高的人时利用率以及更高的飞机装配效率。

多传感器跑道积冰预警无线数据采集系统设计（英文）

针对机场跑道结冰检测与预警问题,开发了一套基于组态软件的模拟机场跑道积冰气象参数无线采集系统。系统利用道面冰点传感器检测模拟跑道内部不同深度的温度和冰点温度,采用Vaisala气象传感器测量道面附近环境温度、风速和湿度等气象数据。重点开发了道面冰点传感器的组态软件驱动程序,实现了道面冰点数据的组态和集成。基于组态软件虚拟串口技术和公共网络通信平台,开发了多通道数据采集与传输模块,解决了飞行区内道面数据无线采集和传输问题。采用组态软件开发了数据中心,实现了道面积冰数据的存储、处理和人机界面。实验结果显示:该系统实现了道面多点积冰数据无线通信,能够采集和记录道面温度、环境温度和风速等积冰数据,为后续道面积冰预警系统建立实验平台和数据分析中心。该系统避开了飞行区内线路敷设和通信频段干扰等问题,为机场飞行区内道面积冰预警问题提供了一种新思路。

考虑跨数影响的单线铁路简支梁桥桥墩地震响应

针对8 m和25 m 2种墩高的单线铁路简支梁桥,研究跨数对中间桥墩地震响应的影响程度。采用OpenSEES程序,分别建立2跨,4跨,6跨和8跨共4种不同跨数的桥梁有限元模型。通过不同方向、不同烈度的地震动作用下地震响应的对比分析,确定跨数对中间桥墩地震响应的影响程度。研究结果表明:在纵向地震动作用下,中间桥墩地震响应随跨数的增加而增加,并在跨数多于4跨时增加趋势变缓;在横向地震动作用下,中间桥墩地震响应随跨数的增加而先增加后减小,并在跨数为4跨时达到最大值。以上趋势随着墩高和地震烈度的增加而减小,但在桥墩屈服前后略有波动。因此,在进行单线铁路简支梁桥的普通高度桥墩地震响应分析时,为了同时提高计算精度和计算效率,建模跨数以4跨为宜。

Study on the Complete Mitochondrial Genome of Qaidam Cattle(Bos taurus)

Qaidam cattle(Bos taurus) is an important endemic breed in Northwest China, which is mainly distributed in the northwest of Qinghai-Tibet Plateau. It has strong adaptive ability to plateau and swamp conditions, such as cold tolerance and insect resistance. In this study, the first complete mitochondrial genome of Qaidam cattle was reported. The circular double-stranded genome is 16 340 bp in size, and contains 13 protein-coding genes, 22 transfer RNA genes, two ribosomal RNA genes, and a D-loop region. The overall nucleotide composition is 33.4% A, 27.2% T, 26.0% C and 13.4% G, with a total A +T content of60.6%. The gene order and composition are similar to those of other B. taurus breeds. Molecular phylogenetic analysis indicated that Qaidam cattle was split as an independent clade and nested within Asian cattle breeds.

A Receiver-Forwarding Decision Scheme Based on Bayesian for NDN-VANET

Named Data Network(NDN) has caused wide concerns in VANET community because NDN uses a content-centric mechanism that naming content rather than the host. However, integrating NDN into VANET(NDN-VANET) also faces several challenges including consumer/provider mobile, broadcast storm problem and so on. In this paper, we propose a Bayesian-based Receiver Forwarding Decision(BRFD) scheme to mitigate the broadcast storm problem incurred by interest packets in NDN-VANET. In the BRFD, vehicles received an interest packet are required to make forwarding decisions based on Bayesian decision theory according to current network conditions obtained by neighbor interaction. However, the receiver-forwarding decision in BRFD can also cause a conflict issue because multiple vehicles forward copies of the same packet at the same time. So a back-off mechanism is introduced in BRFD. Experimental results show that the BRFD algorithm has better performance in several aspects in contrast to probability-based forwarding scheme and "bread crumb" routing.

Searchable Encryption Cloud Storage with Dynamic Data Update to Support Efficient Policy Hiding

Ciphertext policy attribute based encryption(CP-ABE)can provide high finegrained access control for cloud storage.However,it needs to solve problems such as property privacy protection,ciphertext search and data update in the application process.Therefore,based on CP-ABE scheme,this paper proposes a dynamically updatable searchable encryption cloud storage(DUSECS)scheme.Using the characteristics of homomorphic encryption,the encrypted data is compared to achieve efficient hiding policy.Meanwhile,adopting linked list structure,the DUSECS scheme realizes the dynamic data update and integrity detection,and the search encryption against keyword guessing attacks is achieved by combining homomorphic encryption with aggregation algorithm.The analysis of security and performance shows that the scheme is secure and efficient.

成渝地区双城经济圈县域经济时空格局分析

本文选取成渝地区双城经济圈142个县域作为研究样本,基于2001—2019年人均GDP面板数据,利用标准差、变异系数、NICH指数和探索性时空分析(ESDA)分析方法,从时间和空间两个维度深入刻画和研究了成渝地区双城经济圈县域经济空间格局动态演化过程。结果表明,2001—2019年,成渝地区双城经济圈县域经济发展不均衡性的绝对差异不断扩大,相对差异持续缩小;县域经济发展水平和经济增长的分布格局较为一致,但“马太效应”十分显著,绝大多数县域经济增长速度偏慢;2001—2019年的19年间,人均GDP的Moran's I指数均为正值,县域经济呈现明显空间集聚现象,且伴有不断强化趋势;县域经济空间异质性突出,成渝“双核”极化现象明显,不发达地区集中连片分布,“中部孱弱”现象突出。最后,为优化成渝地区双城经济圈县域经济空间格局,本文提出建立健全区域协同规划建设及分享机制、构建“双核”引领的县域经济协调发展格局等政策建议。

Design and Implementation of NOLSR for NDNMANET Routing

Named Data Network(NDN)is an important instance of future internet architectures.NDN-MANET routing is a hot research area.Link State Advertisements(LSAs)flooding is a common method to obtain network topology during routes establishment.However,LSAs flooding often causes a broadcast storm in high-density MANET.Using a MultiPoint Relay(MPR)set proposed in the Optimized Link State Routing protocol(OLSR)can effectively reduce the number of LSAs in the process of route establishment.So,this solution can solve the broadcast storm.Based on OLSR,we design and implement a novel routing Named-data Optimized Link State Routing protocol(NOLSR)for NDN-MANET.In NOLSR,a new neighbor discovery protocol to establish the MPR set is proposed.Only nodes in the MPR set will forward LSAs so that other nodes can obtain a network topology and further establish the routing table.The neighbor discovery protocol can also avoid the problem of unidirectional links which impacts the performance of a network.Finally,we make a comparative analysis between classic flooding and NOLSR by simulation experiment in an NDN emulator mini-NDN.

Study on Complete Mitochondrial Genome of Oula Sheep(Ovis aries)

Mitochondrial genome has been widely used in species identification and gene conservation.In the present study,the complete mitochondrial genome of Oula sheep(Ovis aries)was determined using next-generation sequencing.This genome was16 618 bp(NCBI accession number:KU575248)and contained 13 protein coding genes,22 transfer RNA genes,two ribosomal RNA genes,and a typical control region.The overall nucleotide composition was 33.7%A,27.4%T,25.8%C,and 13.1%G,with a total A+T content of 61.1%.The phylogenetic analysis of selected sheep breeds showed that Oula sheep were clustered within branch A and originated from approximately 6 ka.This mitochondrial genome will provide valuable information for molecular genetic research of Oula sheep.

Investigation on Active and Reactive Combined Spot Price Integrated with Wind Farm

An active and reactive combined spot price model and the corresponding algorithm are introduced in this paper based on the theory of optimal power flow. Different from the traditional economic dispatch in the field of spot price, the objective function is to minimize generation costs based on pricing reactive power. Then considering the characteristics of wind turbines, processing methods of wind farms in optimal power flow is discussed. Finally, the feasibility of the model and the algorithm is verified through the simulation results of IEEE 30 system.

Characterization of the Complete Mitochondrial Genome of Przewalski's Gazelle Procapra przewalskii in Bovidae Family of Artiodactyla

The Przewalski's gazelle,Procapra przewalskii,is one of the most endangered species in China,and is now found only in a single small area around the Lake Qinghai.In this study,the complete mitochondrial genome of P.przewalskii was determined and annotated.The circular genome is 16 547-bp long,containing13 protein-coding genes,22 transfer RNA genes,2 ribosomal RNA genes,and a predicted control region.The overall base composition was 34.0% A,24.7% C,28.3% T,and 13.0% G,with a total A + T content of 62.3%.Phylogenetic analysis of all 19 Bovidae species indicated that P.przewalskii showed a close relationship to Procapra gutturosa.Our results provide a great deal of useful information on further studies for conservation biology of Przewalski's gazelle.

The lysine methyltransferase SMYD2 facilitates neointimal hyperplasia by regulating the HDAC3-SRF axis

Coronary restenosis is an important cause of poor long-term prognosis in patients with coronary heart disease.Here,we show that lysine methyltransferase SMYD2 expression in the nucleus is significantly elevated in serum-and PDGF-BB-induced vascular smooth muscle cells(VSMCs),and in tissues of carotid artery injury-induced neointimal hyperplasia.Smyd2 overexpression in VSMCs(Smyd2-vTg)facilitates,but treatment with its specific inhibitor LLY-507 or SMYD2 knockdown significantly inhibits VSMC phenotypic switching and carotid artery injury-induced neointima formation in mice.Transcriptome sequencing revealed that SMYD2 knockdown represses the expression of serum response factor(SRF)target genes and that SRF overexpression largely reverses the inhibitory effect of SMYD2 knockdown on VSMC proliferation.HDAC3 directly interacts with and deacetylates SRF,which enhances SRF transcriptional activity in VSMCs.Moreover,SMYD2 promotes HDAC3 expression via tri-methylation of H3K36 at its promoter.RGFP966,a specific inhibitor of HDAC3,not only counteracts the pro-proliferation effect of SMYD2 overexpression on VSMCs,but also inhibits carotid artery injury-induced neointima formation in mice.HDAC3 partially abolishes the inhibitory effect of SMYD2 knockdown on VSMC proliferation in a deacetylase activity-dependent manner.Our results reveal that the SMYD2-HDAC3-SRF axis constitutes a novel and critical epigenetic mechanism that regulates VSMC phenotypic switching and neointimal hyperplasia.

Hybrid vibration isolation optimization of a flexible manipulator based on neural network agent model

Segmented Active Constrained Layer Damping(SACLD)is an intelligent vibration-damping structure,which could be applied to the sectors of aviation,aerospace,and transportation engineering to reduce the vibration of flexible structures.Moreover,machine learning technology is widely used in the engineering field because of its efficient multi-objective optimization.The dynamic simulation of a rotational segmental flexible manipulator system is presented,in which enhanced active constrained layer damping is carried out,and the neural network model of Genetic Algorithm-Back Propagation(GA-BP)algorithm is investigated.Vibration suppression and structural optimization of the SACLD manipulator model are studied based on vibration mode and damping prediction.The modal responses of the SACLD manipulator model at rest and rotation are obtained.In addition,the four model indices are optimized using the GA-BP neural network:axial incision size,axial incision position,circumferential incision size,and circumferential incision position.Finally,the best model for vibration suppression is obtained.

Quantitative characterization of filamentous fungal promoters on a single-cell resolution to discover cryptic natural products

Characterization of filamentous fungal regulatory elements remains challenging because of time-consuming transformation technologies and limited quantitative methods.Here we established a method for quantitative assessment of filamentous fungal promoters based on flow cytometry detection of the superfolder green fluorescent protein at single-cell resolution.Using this quantitative method,we acquired a library of 93 native promoter elements from Aspergillus nidulans in a high-throughput format.The strengths of identified promoters covered a 37-fold range by flow cytometry.P_(zipA) and P_(sltA)were identified as the strongest promoters,which were 2.9-and 1.5-fold higher than that of the commonly used constitutive promoter P_(gpdA).Thus,we applied P_(zipA)and P_(sltA)to activate the silent nonribosomal peptide synthetase gene Afpes1 from Aspergillus fumigatus in its native host and the heterologous host A.nidulans.The metabolic products of Afpes1 were identified as new cyclic tetrapeptide derivatives,namely,fumiganins A and B.Our method provides an innovative strategy for natural product discovery in fungi.