基于正确解码率的ADS-B天线配置模型分析

提出一种广播式自动相关监视(ADS-B)天线配置分析模型,该模型可实现基于本地具体情况获得满足空管管制要求的ADS-B天线部署方案,为后续ADS-B站点部署实施时选择定向/全向天线提供决策工具。本文以报文正确解码率作为评估定向/全向天线效果的直接指标,从飞机数量、雷达/TCAS部署情况、飞机应答/广播速率等3个角度出发,获得空域单目标每秒发送报文的数量,分析其与定向/全向ADS-B接收设备报文解码率的关联性,从而得到定向天线与全向天线配置下报文解码率分析模型,然后设置模型相关参数,通过模型解算获得相应的正确解码率。通过实际录取数据对该模型正确性进行相关验证,结果与理论模型基本保持一致,证明ADS-B天线配置分析模型是正确有效的。

基于IMMKF算法的ADS-B监视应用目标跟踪

目标跟踪是机载广播式自动相关监视(ADS-B)应用的基础功能,对提升航空器周边的弱机动民航飞机目标跟踪性能具有重要意义。提出一种基于交互式多模型卡尔曼滤波(IMMKF)算法的ADS-B监视应用目标跟踪方法。首先,针对弱机动背景下的民航飞机的飞行特点,建立包含匀速模型和标准协同转弯模型的运动模型集,并对模型进行线性化近似;然后,将模型预测和ADS-B状态矢量量测数据作为IMMKF算法中多个并行卡尔曼滤波器的输入,进行并行滤波;最后,计算得到目标状态矢量的估计和模型近似概率,并作为下一次迭代的输入。结果表明:相比于基于匀速模型的卡尔曼滤波目标跟踪方法,IMMKF算法的位置跟踪误差降低了59%,速度跟踪误差降低了77%,显著提升了状态估计性能,具备较高的跟踪精度、稳健性与计算效率,在ADS-B监视应用中具有实际应用价值与借鉴意义。

Multilevel security model for ad hoc networks

Modern battlefield doctrine is based on mobility, flexibility, and rapid response to changing situations. As is well known, mobile ad hoc network systems are among the best utilities for battlefield activity. Although much research has been done on secure routing, security issues have largely been ignored in applying mobile ad hoc network theory to computer technology. An ad hoc network is usually assumed to be homogeneous, which is an irrational assumption for armies. It is clear that soldiers, commanders, and commanders-in-chief should have different security levels and computation powers as they have access to asymmetric resources. Imitating basic military rank levels in battlefield situations, how multilevel security can be introduced into ad hoc networks is indicated, thereby controlling restricted classified information flows among nodes that have different security levels.

基于AD-RF模型的互联网金融信用风险评估

基于互联网金融平台非平衡交易记录数据样本,利用“软信息”特征构建评估指标体系,结合ADASYN算法和随机森林模型,提出改进后的AD-RF信用风险评估模型。该信用风险评估模型优于传统随机森林模型。互联网金融面临的信用风险主要源于对借款人的道德水平高低、还款能力大小、违约成本大小的未知和借款利率的变化。

Adding-Point Strategy for Reduced-Order Hypersonic Aerothermodynamics Modeling Based on Fuzzy Clustering

Reduced order models（ROMs） based on the snapshots on the CFD high-fidelity simulations have been paid great attention recently due to their capability of capturing the features of the complex geometries and flow configurations. To improve the efficiency and precision of the ROMs, it is indispensable to add extra sampling points to the initial snapshots, since the number of sampling points to achieve an adequately accurate ROM is generally unknown in prior, but a large number of initial sampling points reduces the parsimony of the ROMs. A fuzzy-clustering-based adding-point strategy is proposed and the fuzzy clustering acts an indicator of the region in which the precision of ROMs is relatively low. The proposed method is applied to construct the ROMs for the benchmark mathematical examples and a numerical example of hypersonic aerothermodynamics prediction for a typical control surface. The proposed method can achieve a 34.5% improvement on the efficiency than the estimated mean squared error prediction algorithm and shows same-level prediction accuracy.

Total Pairwise Quantum Correlation and Entanglement in a Mixed-Three-Spin Ising-XY Model with Added Dzyaloshinskii-Moriya Interaction under Decoherence

We investigate the behavior of geometric global quantum discord （GGQD） and concurrence （C） between half- spins of a mixed-three-spin （1/2, 1, 1/2） system with the Ising-XY model for which spins （1, 1/2） have the Ising interaction and half-spins （1/2, 1/2） have both XY and the Dzyaloshinskii Moriya interactions together, under the decoherence action. A single-ion anisotropy property with coefficient ζ is assumed for the spin-integer. This system which includes an analytical Hamiltonian is considered at the front of an external homogeneous magnetic field B in thermal equilibrium. Finally, we compare GGQD and C and express some interesting phase flip reactions of the total quantum correlation and pairwise entanglement between spins （1/2, 1/2）. Generally, we conclude that the concurrence and GGQD have different behaviors under the phase flip channel.

基于ADE的IFC到CityGML层次转换模型

新型城市化建设和管理过程中,借助建筑信息模型(building information modeling,BIM)与地理信息系统(geographic information system,GIS)的数据集成,不但能实现建筑物的精细化表达,而且室外信息得以兼顾,实现空间分析及室内外一体化表达。但BIM与GIS两种不同的数据格式无法直接实现数据的互通。为此,首先分析了模型IFC和CityGML在文档形式等方面的差异,并实现了多个简单建筑物IFC模型到CityGML3.0 LOD2、LOD3的转换。其次,针对上述数据集成实验中语义丢失问题,扩展GIS的CityGML3.0数据格式,提出CityGML B-Con扩展模型,完善IFC到CityGML3.0的一对一映射关系。最后,实现多个不同复杂程度建筑物IFC模型到CityGML B-Con扩展模型的转换。实验结果表明,利用CityGML B-Con模型能实现BIM与GIS的数据集成。宏观层面来说,能够增强转换后建筑物外观的细节程度,微观层面而言,BuildingConstructiveElement和BuildingInstallation的子类得以区分,IfcStair、IfcRamp和IfcBeam等建筑构件都能通过一对一映射的方式转换至CityGML中,克服了CityGML原有标准在建筑物构件表达方面的缺陷,有效减少了BIM源数据语义信息的丢失。

The Research on QoS Model Design in Mobile Ad Hoc Networks

Wireless Ad Hoc Networks is a special kind of wireless communication network. With the great development of multimedia applications, how to provide QoS guarantee in the MAC layer is the hot topic in wireless ad hoc network (MANET). This paper designed a QoS model in MANET. The feasibility and reliability of this model is analyzed and verified. Compared with the traditional model, the proposed approach is improved in MAC layer in order to achieve high control rate of low-priority transactions.

Analysis of reactive routing protocols for mobile ad hoc networks in Markov models

Mobile ad hoc networks （MANETs） have become a hot issue in the area of wireless networks for their non-infrastructure and mobile features. In this paper, a MANET is modeled so that the length of each link in the network is considered as a birthdeath process and the space is reused for n times in the flooding process, which is named as an n-spatiai reuse birth-death model （n-SRBDM）. We analyze the performance of the network under the dynamic source routing protocol （DSR） which is a famous reactive routing protocol. Some performance parameters of the route discovery are studied such as the probability distribution and the expectation of the flooding distance, the probability that a route is discovered by a query packet with a hop limit, the probability that a request packet finds a τ-time-valid route or a symmetric-valid route, and the average time needed to discover a valid route. For the route maintenance, some parameters are introduced and studied such as the average frequency of route recovery and the average time of a route to be valid. We compare the two models with spatial reuse and without spatial reuse by evaluating these parameters. It is shown that the spatial reuse model is much more effective in routing.

Added Mass Effect and an Extended Unsteady Blade Element Model of Insect Hovering

During the insect flight, the force peak at the start of each stroke contributes a lot to the total aerodynamic force. Yet how this force is generated is still controversial. Two current explanations to this are wake capture and Added Mass Effect （AME） mechanisms. To study the AME, we present an extended unsteady blade element model which takes both the added mass of fluid and rotational effect of the wing into account. Simulation results show a high force peak at the start of each stroke and are quite similar to the measured forces on the physical wing model. We found that although the Added Mass Force （AMF） of the medium contributes a lot to this force peak, the wake capture effect further augments this force and may play a more important role in delayed mode. Furthermore, we also found that there might be an unknown mechanism which may augment the AME during acceleration period at the start of each stroke, and diminish the AME during deceleration at the end of each stroke.

Virtual reality mobility model for wireless ad hoc networks

For wireless ad hoc networks simulation, node＇s mobility pattern and traffic pattern are two key elements. A new simulation model is presented based on the virtual reality collision detection algorithm in obstacle environment, and the model uses the path planning method to avoid obstacles and to compute the node＇s moving path. Obstacles also affect node＇s signal propagation. Considering these factors, this study implements the mobility model for wireless ad hoc networks. Simulation results show that the model has a significant impact on the performance of protocols.

The impact of hidden node on model of ad hoc network

To deal with hidden nodes in ad hoc network, we take throughput as the metric to evaluate the performance of network. Firstly, we modeled the MAC layer of ad hoc network based on 802.11 DCF without the existence of hidden nodes. By means of the proposed model, we evaluated the throughput performance of DCF in multi-hop wireless networks. Secondly, we performed simulations to validate this model. The outcome of comparison is that there exists much difference in throughput between the model and the simulation. For reducing this difference, we modified the model by involving hidden nodes under the condition that the AODV route protocol was chosen, and analytically analyzed the influence of hidden nodes on theoretical throughput. At last, we validated the accuracy of this model by comparing the analytical results with simulation results.

分形界面吸附行为初探

煤层气吸附解吸机理研究是揭示煤层气成藏机理及高效开发煤层气的基础。已有研究表明,煤储层孔隙结构非常复杂且具有分形特征,煤层气在孔-固界面的吸附行为明显受到煤孔隙结构特征的影响。对比分析几种常用气-固界面上的吸附模型,总结这些模型的特点和适用条件,指出当前吸附模型在分形界面吸附行为的描述和应用上均未摆脱吸附选择性的平稳假设,尚未考虑吸附厚度的尺度不变特征。而分形拓扑理论可以有效标定分形对象的尺度不变属性,为分形界面的等效表征提供了理论支撑。因此,结合上述模型对气-固界面吸附行为的描述,借助分形拓扑理论提出煤储层孔-固界面上分形吸附行为的相关假设及其控制机理,构建基于吸附拓扑的单层吸附模型。在此基础上,通过设置不同的吸附拓扑参数组合获取其等温吸附曲线,分析得出,随着吸附压力的升高,吸附覆盖率表现出指数、线性和对数3种不同的增长趋势,而吸附热表现为对数减小趋势。结果显示,不同的吸附拓扑参数组合会得到不同类型的等温吸附曲线,在一定程度上弥补了Langmuir方程只能描述单一类型等温吸附线的不足。为了验证吸附模型的适用性,结合沁水盆地武乡区块富有机质泥页岩的液氮吸附实验数据,对比了实际等温吸附曲线与模拟吸附曲线的差异。结果表明,通过调整各吸附拓扑参数之间的组合关系,可以使等温吸附模拟曲线与实际吸附曲线的趋势始终保持一致。最后,探讨了吸附解吸机理的研究方向,类比电子层提出了吸附层的概念,指出发展分形动力学描述模型是解释煤层气吸附解吸规律的关键。

紫外光非直视通信研究进展

紫外光技术在军事和民用领域有着广泛的应用,如空间探测、紫外光制导、紫外干扰、电晕放电检测和军事通信等领域。文章从紫外光的单次和多次散射出发,介绍了紫外光通信的国内外进展,分析了紫外光通信中的不同链路情况,针对非直视链路紫外通信的脉冲展宽效应和大气湍流影响进行了探讨,总结了紫外光Ad Hoc网络,最后对紫外光通信的发展进行了展望。

中国经济国内国际双循环测度——基于三种GDP分解的比较分析

依据单一GDP分解方法测度双循环存在多种缺陷。本文从增加值流转视角比较分析三种GDP分解方法下的直接指标,构建一种以间接指标测度双循环的新框架,并将其应用于中国经济双循环格局演化分析和国际比较分析。研究表明,1995—2018年,中国制造业国内循环比例呈逐渐下降又大幅回调过程,本质上是对中国双循环格局“大内循环倾向”特征的回归,并不代表“国内大循环为主”经济发展格局已经形成;不同经济体双循环格局具有明显异质性,即具有“大内循环倾向”或“小内循环倾向”。这种异质性相对稳定,经济体双循环格局的演变进程主要表现为国内外市场关联和上下游产业关联两种结构力量作用下,在双循环类型空间的局部调整。从构建以国内大循环为主体,国内国际双循环相互促进的新发展格局出发,反映国内国际循环比例的直接指标不是合适的政策目标,中国应根据不同行业特点,根据间接指标所反映的双循环格局类型和结构特征,聚焦产业链整合和治理挖掘增长潜力。

RCEP生效对国际服务贸易影响作用研究——基于增加值贸易视角

RCEP作为当前世界范围内规模最大、影响范围最广的区域自由贸易体系,在服务贸易方面做出了高水平的开放承诺,它是中国构建高标准自由贸易区网络进程中的重要抓手。以1995-2018年全球范围内66个国家服务部门的双边出口数据为样本,运用结构引力模型和泊松拟极大似然估计方法,实证研究了RCEP对服务部门增加值贸易以及福利的影响作用。反事实模拟分析结果表明,RCEP对成员国服务部门总出口和国内增加值出口均有显著的促进作用,而非成员国将在整体上受损;RCEP对一国福利的影响较小,对一国出口的影响较大;对中国而言,RCEP将大幅提高中国对日本的服务部门总出口和国内增加值出口。此外,将RCEP与CPTPP进行比较发现,RCEP对我国服务部门增加值贸易的正向影响幅度小于CPTPP。

BDNF、NGF对AD模型鼠脑移植区胚胆碱能神经元发育生长的调控

目的探讨脑源性神经营养因子（ＢＤＮＦ）、神经生长因子（ＮＧＦ）对ＡＤ模型鼠脑植入胚基底前脑后行为改善和移植区胚胆碱能神经元发育生长的影响。方法用使君子酸损毁ＳＤ大鼠基底大细胞核制成ＡＤ模型，分成ＢＤＮＦ、ＮＧＦ、ＢＤＮＦ＋ＮＧＦ及单纯移植对照４组。在额、顶叶皮质植入同种胚基底前脑细胞悬液，前３组含相应神经营养因子，移植后每２ｄ向侧脑室灌注相应神经营养因子共７次。移植后１、２．５和４个月时行避暗回避试验和跳台试验，最后脑切片经ＡＣｈＥ组织化学、ＣｈＡＴ和ＬＮＧＦＲ免疫组织化学等染色，对移植区中的神经元及纤维作定量分析和图像处理。结果移植后应用神经营养因子的动物较对照组行为改善明显迅速，ＢＤＮＦ＋ＮＧＦ组行为改善又较ＢＤＮＦ组或ＮＧＦ组明显。形态学证实，应用神经营养因子动物移植区中ＡＣｈＥ阳性神经元数、１６９００μｍ２网格中ＡＣｈＥ阳性纤维交点数及ＡＣｈＥ阳性神经元面积均优于对照组，ＢＤＮＦ＋ＮＧＦ组的结果又好于ＢＤＮＦ组或ＮＧＦ组。结论ＢＤＮＦ与ＮＧＦ一样能促进植入胚基底前脑的ＡＤ模型鼠行为改善和移植区胚胆碱能神经元的发育生长，ＢＤＮＦ和ＮＧＦ联合使用比单独使用一种因子更为有效。

Experimental and Numerical Investigations on Vibration Characteristics of a Loaded Ship Model

在这篇论文，在有限液体领域的结构的颤动特征用 a coupled 被分析有限元素方法。增加的集体矩阵与有限元素方法被计算(女性) 由 8 节点声学的液体元素。在有限液体领域的结构的颤动特征被计算联合结构女性的集体矩阵。由写相关程序，沉没伸臂的颤动特征上的数字分析在有限液体领域和装载轮船模型的矩形的板被执行。为在空中并且在水里的装载轮船模型的一个形式的鉴定实验被进行，实验结果验证数字分析的可靠性。数字方法能在有限液体领域在颤动特征和结构的声学的放射问题上被用于进一步的研究。

川芎嗪对AD模型小鼠海马胆碱能系统的影响

目的探讨川芎嗪对D-半乳糖(D-gal)所致AD模型小鼠海马胆碱能系统功能的影响。方法C57BL/6J小鼠颈背部皮下注射2%D-gal100mg.Kg-1.d-1,连续40d造模。第3周起各组分别灌胃生理盐水(正常对照组、模型组)、川芎嗪(高、低剂量组)和哈伯因(阳性对照组)。给药结束后进行水迷宫训练,24h后进行学习记忆功能测试和海马胆碱乙酰基转移酶(chAT)与乙酰胆碱酯酶(AchE)活性测定以及M受体放射性配基结合分析。结果与正常对照组相比,D-gal模型组小鼠学习记忆能力和M受体含量均明显下降(P<0.05～0.01)。模型组chAT和AchE活性也有轻微下降,但与对照组比较差异无统计学意义。给予川芎嗪可明显改善AD模型小鼠的学习记忆功能,增强海马chAT活性(P<0.01)和AchE活性(P<0.05),上调M受体数目(P<0.005)。结论川芎嗪可明显提高模型小鼠的学习记忆能力,改善海马胆碱能系统功能。