关于《在求解指派问题的匈牙利法中划最少覆盖线的一种新方法》一文的错误

东南大学张淮中同志对我院宁宣熙同志的《在求解指派问题的匈牙利法中划最少覆盖线的一种新方法》(载本刊第20卷第4(Ⅰ)期,1988年12月)一文提出了批评,指出按该经验方法并不能给出一般指派问题的最少覆盖线,并提供了反例。现除发表张文外,发表了宁宣熙同志的答复,以便使读者有一个正确的了解。

蜂窝无线通信系统中的数学建模和优化技术

蜂窝无线通信系统中的数学建模和优化技术是实现高效、可靠和可扩展的无线通信系统的关键技术之一。文章主要研究蜂窝无线通信系统中的数学建模和优化技术,介绍了蜂窝网络的基本架构和通信模型,并使用数学方法来描述和优化无线通信系统。在空间信号链路损失的条件下,文章结合最小保护场强度、重复系统强度和余量等合理参数的分析和确定,推导了重复覆盖线的表达式,并对移动通信系统的中心提取器模型进行修正,得到顶点中心激励模型。与传统中心激励模型相比,文章改进的模型能够将覆盖区域增加4%,覆盖用户增加22%。

处理Non-LTE谱线覆盖效应的有效方法——近似A算子法

本文在分析完全线性化方法不能很好地处理Non-LTE谱线覆盖效应的基础上,介绍了一种由Werner(1986年)引进的能有效的处理Non-LTE谱线覆盖效应的计算Non-LTE恒星大气模型的方法——近似A算子法。并对这种方法的优缺点和可能的应用作了分析和讨论。

山区铁路GSM-R交织单网冗余覆盖设计

正我国山区铁路多处于崇山峻岭中,大量隧道群连续出现,地形复杂,使无线电波的传播情况更为复杂多变。在复杂的地形条件下采用GSM-R交织单网覆盖方案,实现网络的高性能和高可靠性是GSM-R网络无线覆盖设计面临的难题和巨大挑战。

单纱棉盖丝织物的设计及覆盖形式分析

普通棉盖丝织物都是将添纱组织或双面空气层变化组织作为地组织来进行花型变换和结构设计,但是织物手感厚实,成衣克质量偏高,不宜用来制作夏季服装,为此介绍了几款选用单纱和单丝经过适当的工艺变化和纱线配置后,织造的仿单面棉盖丝织物的编织工艺,如网眼覆盖型、毛圈覆盖型、竖条覆盖型、浮线覆盖型棉盖丝织物等。

基于手机信令数据的地铁站点线站位人口岗位统计系统研究

为更加方便、快捷、准确地统计城市轨道交通线站位选址过程中站点缓冲区范围覆盖人口岗位数,文章结合联通手机信令数据,基于百度地图API平台开发了求解线站位覆盖区域内所覆盖人口岗位数的系统,然后结合广州地铁11号线利用该系统对地铁站点覆盖接驳进行了实例研究。实践证明,此系统相较其他方法更加快速,分析结果更为准确,只需得到相关的手机信令数据,就可直接进行各种深入分析研究,可以直接根据相关结果确定线站位优化的方向,如站间距、车站位置等,可为优化决策提供重要参考。

对张淮中同志的答复

张淮中同志对拙文《在求解指派问题的匈牙利法中划最少覆盖线的一种新方法》的批评,由《南京航空学院学报》编辑部转给了我,我十分感激张淮中同志钻研了我的文章,并提出了反例。 首先应当肯定张淮中同志的反例是正确的,这说明我的经验方法尚有不足之处。 张文的反例是一类不连通的二部图。而我的经验规则是从研究连通的二部图得出的,后来推广到非连通的二部图。现在看起来,原规则在连通的二部图中是适用的,但在推广到非连通的二部图中尚有不足之处,很感谢张淮中同志发现了这个问题。

工作分配的方法数量与最优解探析

工作分配是人力资源管理的一项重要职能,而实际生活中的工作分配问题总会受到很多约束条件的.本文根据实际情况,用组合数学中的车多项式计算了在约束务件下的工作分配的方法数量并且应用匈牙利算法给出了两种最优工作分配方案.

Modified particle swarm optimization-based antenna tilt angle adjusting scheme for LTE coverage optimization

In order to solve the challenging coverage problem that the long term evolution（ LTE） networks are facing, a coverage optimization scheme by adjusting the antenna tilt angle（ ATA） of evolved Node B（ e NB） is proposed based on the modified particle swarm optimization（ MPSO） algorithm.The number of mobile stations（ MSs） served by e NBs, which is obtained based on the reference signal received power（RSRP） measured from the MS, is used as the metric for coverage optimization, and the coverage problem is optimized by maximizing the number of served MSs. In the MPSO algorithm, a swarm of particles known as the set of ATAs is available; the fitness function is defined as the total number of the served MSs; and the evolution velocity corresponds to the ATAs adjustment scale for each iteration cycle. Simulation results showthat compared with the fixed ATA, the number of served MSs by e NBs is significantly increased by 7. 2%, the quality of the received signal is considerably improved by 20 d Bm, and, particularly, the system throughput is also effectively increased by 55 Mbit / s.

Coordinate-free k-coverage hole detection algorithm in wireless sensor networks

For wireless sensor networks, a simple and accurate coordinate-free k-coverage hole detection scheme is proposed. First, an algorithm is presented to detect boundary cycles of 1-coverage holes. The algorithm consists of two components, named boundary edge detection and boundary cycle detection. Then, the 1-coverage hole detection algorithm is extended to k-coverage hole scenarios. A coverage degree reduction scheme is proposed to find an independent covering set of nodes in the covered region of the target field and to reduce the coverage degree by one through sleeping those nodes. Repeat the 1-coverage hole detection algorithm and the higher order of coverage holes can be found. By iterating the above steps for k-1 times, the boundary edges and boundary cycles of all k-coverage holes can be discovered. Finally, the proposed algorithm is compared with a location-based coverage hole detection algorithm. Simulation results indicate that the proposed algorithm can accurately detect over 99% coverage holes.

A new patch antenna with metamaterial cover

A metamaterial was introduced into the cover of a patch antenna and its band structure was analyzed. The metama- terial cover with correct selection of the working frequency increases by 9.14 dB the patch antenna’s directivity. The mechanism of metamaterial cover is completely different from that of a photonic bandgap cover. The mechanism of the metamaterial cover, the number of the cover’s layers, and the distance between the layers, were analyzed in detail. The results showed that the metamaterial cover, which works like a lens, could effectively improve the patch antenna’s directivity. The physical reasons for the improvement are also given.

Efficient Algorithm for K-Barrier Coverage Based on Integer Linear Programming

Barrier coverage of wireless sensor networks is an important issue in the detection of intruders who are attempting to cross a region of interest.However,in certain applications,barrier coverage cannot be satisfied after random deployment.In this paper,we study how mobile sensors can be efficiently relocated to achieve k-barrier coverage.In particular,two problems are studied:relocation of sensors with minimum number of mobile sensors and formation of k-barrier coverage with minimum energy cost.These two problems were formulated as 0–1 integer linear programming(ILP).The formulation is computationally intractable because of integrality and complicated constraints.Therefore,we relax the integrality and complicated constraints of the formulation and construct a special model known as RELAX-RSMN with a totally unimodular constraint coefficient matrix to solve the relaxed 0–1 ILP rapidly through linear programming.Theoretical analysis and simulation were performed to verify the effectiveness of our approach.

Degradation of Wetlands on the Qinghai-Tibet Plateau:A Comparison of the Effectiveness of Three Indicators

The Qinghai-Tibet Plateau encompasses a large quantity of wetlands, some of which have been degraded to varying severity levels. In the literature, a number of degradation indicators have been proposed to evaluate ecological health of wetlands, but their effectiveness in the plateau environment remains unknown. In this study, we assessed the effectiveness of three degradation indicators, soil moisture content at lo em deep, vegetative cover, and density of pika burrows. The degradation severity of wetlands in Maduo County on the Qinghai-Tibet Plateau is enumerated at four levels, intact, slight, moderate and severe. Analysis of xo6 samples collected in the field demonstrates that the density of pika burrows is the least reliable indicator. By comparison, vegetative cover and underlying soil moisture content are more reliable, even though neither is a perfect indicator as the difference among adjacent levels of severity as revealed by t-test is not always statistically significant. The imperfection of vegetative cover as an indicator is due to its variation among different types of wetlands. The limitation of moisture content is attributed to its non-linear relationship with wetland degradation. Above the threshold of about 50% in moisture content wetlands are unlikely to be degraded. It is recommended that moisture be measured at the point near the surface and vegetative cover be further differentiated by species in order to improve their effectiveness.

Determination of minimum cover depth for shallow tunnel subjected to water pressure

Prediction of the state of roof collapse is a big challenge in tunnel engineering, while the limit analysis theory makes it possible to derive the analytical solutions of the collapse mechanisms. In this work, an exact solution of collapsing shape in shallow underwater tunnel is obtained by using the variation principle and the upper bound theorem based on nonlinear failure criterion. Numerical results under the effect of river water and supporting pressure are derived and discussed. The maximum water depth above the river bottom surface is determined under a given buried depth of shallow cavities and the critical depth of roof collapse is obtained under a constant river depth. In comparison with the previous results, the present solution shows a good agreement with the practical results.

5G数字光纤直放站及工程设计方案的探究

国内已建成了超115.9万座5G基站,占到了全球已建成5G基站数量的70%,三大运营商的对高价值区域的室外5G无线信号覆盖已基本完成,5G无线信号覆盖将逐步从高价值区域走向中低价值区域,中低价值区域面积广,人员分布稀疏,5G无线信号覆盖成本将大幅上升,5G基站的利用率将大幅下降,成本上升,利用率下降将导致回收期延长,采用5G数字光纤直放站进行5G无线信号覆盖将是大的趋势,5G数字光纤直放站在应用时产生的重叠覆盖问题需在勘察设计时就进行规避,文章探究了数字光纤直放站的基本概况应用。

Hot-corrosion mechanism of Ni-Cr coatings at 650℃ under different simulated corrosion conditions

The oxidation and lower temperature hot corrosion (LTHC) processes occurring on the surface of Ni-Cr coatings pro-duced by high velocity arc spray (HVAS) were studied. Several different conditions were studied under simulated boiler conditions at 650 ℃. The protection effect of an Al coating deposited by HVAS onto the Ni-Cr coating was also investigated. Microscope, X-ray diffraction and corrosion rate curves have been used to analyze corrosion mechanisms. The experimental results show that: 1) The oxidation rates are almost superposed in both air (no SO3) and in simulated coal-fired gas (containing SO3) as long as no salt was present on the surface. These rate curves show a logarithmic relationship. 2) When the surface is coated with salt (75%K2SO3 + 25%Na2SO3) the rate curve for LTHC of the Ni-Cr coated surface shows a parabolic shape in the simulated coal-fire flue gas. In air only the oxidation reaction takes place, the second type of LTHC was not seen. And 3) the Al over coating on the Ni-Cr enhances resistance to LTHC because an inter-metallic compound, Al3Ni2, forms at the Al/Ni-Cr interface and because of the increase in coating thickness.

NEW METHOD OF MINING INCOMPLETE DATA

The data used in the process of knowledge discovery often includes noise and incomplete information. The boundaries of different classes of these data are blur and unobvious. When these data are clustered or classified, we often get the coverings instead of the partitions, and it usually makes our information system insecure. In this paper, optimal partitioning of incomplete data is researched. Firstly, the relationship of set cover and set partition is discussed, and the distance between set cover and set partition is defined. Secondly, the optimal partitioning of given cover is researched by the combing and parting method, acquiring the optimal partition from three different partitions set family is discussed. Finally, the corresponding optimal algorithm is given. The real wireless signals offten contain a lot of noise, and there are many errors in boundaries when these data is clustered based on the tradional method. In our experimant, the proposed method improves correct rate greatly, and the experimental results demonstrate the method's validity.

基于互联网OTT数据的5G网络规划分析

5G网络是国家新型基础设施建设的重要组成部分,未来的5G网络正朝着网络多元化、综合化、智能化的方向演进,5G网络的总体规划的优劣直接影响信息网络基础设施的覆盖广度、深度和用户感知,是关系智慧城市、车联网、工业互联网等信息通信产业发展的重要基础。因此,本文从铁塔公司和运营商5G网络规划存在的困难和问题入手,提出基于互联网OTT数据的5G无线网络规划策略。

A Mechanism for Biological Control-Tempo-Spatial Synchronization of Natural Enemy and Insect Pest Population Dynamics at the Peak by Increase of Biodiversity

To reveal the mechanism of control of the Woolly Apple Aphid （Eriosoma lanigerum Hausm, WAA） by increase of biodiversity in the apple orchard, a consecutive two-year field trials were conducted in Yurman province, China. The results showed that the peak of natural enemy density curve in the cover cropping orchard was well temporally synchronized with that of the WAA density on trees, but did not synchronize with that of WAA density on trees in clean orchard. In addition, the frequency of natural enemies and WAA within a same sample in cover cropping orchard was obviously higher than that in clean cultivated orchard during the peak of population curves, indicating that natural enemies spatially synchronized with aphids. The density of WAA for the whole growing season in cover cropping orchard was much less than that in clean orchard. Therefore, the temporal-spatial synchrony of natural enemy and aphid populations was proposed as one of the mechanisms for aphid control in cover cropped orchards.

A Coverage-Aware Unequal Clustering Protocol with Load Separation for Ambient Assisted Living Based on Wireless Sensor Networks

Ambient Assisted Living(AAL) is becoming an important research field. Many technologies have emerged related with pervasive computing vision, which can give support for AAL. One of the most reliable approaches is based on wireless sensor networks(WSNs). In this paper, we propose a coverage-aware unequal clustering protocol with load separation(CUCPLS) for data gathering of AAL applications based on WSNs. Firstly, the coverage overlap factor for nodes is introduced that accounts for the degree of target nodes covered. In addition, to balance the intra-cluster and inter-cluster energy consumptions, different competition radiuses of CHs are computed theoretically in different rings, and smaller clusters are formed near the sink. Moreover, two CHs are selected in each cluster for load separation to alleviate the substantial energy consumption difference between a single CH and its member nodes. Furthermore, a backoff waiting time is adopted during the selection of the two CHs to reduce the number of control messages employed. Simulation results demonstrate that the CUCPLS not only can achieve better coverage performance, but also balance the energy consumption of a network and prolong network lifetime.