Okumura Hata Propagation Model Optimization in 400 MHz Band Based on Differential Evolution Algorithm: Application to the City of Bertoua

Propagation models are the foundation for radio planning in mobile networks. They are widely used during feasibility studies and initial network deployment, or during network extensions, particularly in new cities. They can be used to calculate the power of the signal received by a mobile terminal, evaluate the coverage radius, and calculate the number of cells required to cover a given area. This paper takes into account the standard k factors model and then uses the differential evolution algorithm to set up a propagation model adapted to the physical environment of the Cameroonian cities of Bertoua. Drive tests were made on the LTE TDD network in the city of Bertoua. Differential evolution algorithm is used as the optimization algorithm to deduct a propagation model which fits the environment of the considered town. The calculation of the root mean square error between the actual data from the drive tests and the prediction data from the implemented model allows the validation of the obtained results. A comparative study made between the RMSE value obtained by the new model and those obtained by the Okumura Hata and free space models, allowed us to conclude that the new model obtained is better and more representative of our local environment than the Okumura Hata currently used. The implementation shows that Differential evolution can perform well and solve this kind of optimization problem;the newly obtained models can be used for radio planning in the city of Bertoua in Cameroon.

THE MODULATIONAL THEORY OF NONLINEAR GRAVITY-WAVE IN FLUID WITH VARYING DEPTH AND NONUNIFORM CURRENT

By means of WKB expansions, new fourth order evolution equations are derived for two-dimensional Stokes waves over the bottom with arbitrary depth. The effects of slowly varying depth h= h (ε~2 x) and current U=U(ε~2x, ε~2t, ε~4z) on the evolution of a packet of Stokes waves are considered as well. In addition, numerical simulation is performed for the evolution of single envelope by finite-difference method.

ON EXPONENTIAL STABILITY OF NON-AUTONOMOUS STOCHASTIC SEMILINEAR EVOLUTION EQUATIONS

Sufficient conditions for the exponential stability of a class of nonlinear, non-autonomous stochastic differential equations in infinite dimensions are studied. The analysis consists of introducing a suitable approximating solution systems and usig a limiting argument to pass on stability of strong solutions to mild ones. Consequently, under these conditions the random attractors of given stochastic systems are reduced to zero with exponential decay. Lastly, two examples are investigated to illustrate the theory.

Theoretical Study on N=126 Shell Evolution

The nuclei around magic number N=126 are investigated in the deformed relativistic mean field (RMF)model with effective interactions TMA.We focus investigations on the N=126 isotonic chain.The N=126 shellevolution is studied by analyzing the variations of two-neutron (proton) separation energies,quadruple deformations,single particle levels etc.The good agreement of two-neutron separation energies between experimental data and calculatedvalues is reached.The RMF theory predicts that the sizes of N=126 shell become smaller and smaller withthe increasing of proton number Z.However,the N=126 shell exists in our calculated region all along.According tothe calculated two-proton separation energies,the RMF theory suggests ^(220)Pu is a two-proton drip-line nucleus in theN=126 isotonic chain.

Animation of Chinese Characters： Evolution of Shapes and Styles

Hanzi （Chinese characters） has a long history and affluent contents. To promote the popularity of historical and cultural knowledge of Chinese characters, an online program has been launched by Beihang University and Beijing Normal University to explain Chinese characters＇ original meanings and evolution processes with vivid and expressive animation videos. Currently, More than 1,000 videos can be accessed through the website “http：//www.chinesecharacter.org/”. Besides these online resources, a human-computer interaction system is also proposed to simulate clerical changes of Chinese characters through computer morphing technology. What we want is to make the teaching and learning of Chinese characters more reasonable, more easily understandable and more interesting.

The New Detection and the Basic Characteristics of the Structural System of Taiwan Region of China—Using the Earth Satellite's Remote-sensing Images to Explain the Structural System of Taiwan Region of China

This text uses the regional geological investigation data and the remote sensing image data of earth-satellite remote sensing to synthetically analyze the structural system of Taiwan region of China. Authors detection-marked and assurance-marked and divided 5 kinds of structural system of the Taiwan region: (1) the wreath-shaped structural system, (2) the N-N-E oriented structural system, (3) the S-N oriented structural system, (4) the N-E oriented structural system, (5) the arc-shaped structural system. Combination of the texture faces and associated method were adopted to recover and reconstruct the structural evolution sequences and the formation periods. In this paper, problems such as the development process in geology etc. are also discussed, contributing new information to research the structural field of the East Asia and its tectonic plate movements and structural actions inside the land plate .

OFDM系统中导频信号的设计方法

从系统设计的角度研究了正交频分复用(OFDM)系统中的信道估计技术,提出一种最优导频图样的设计方法.该方法首先根据信道的最大多径时延和最大多普勒频移来确定导频符号的时域和频域间隔,并利用穷举法列举所有可能的导频图样,然后根据估计信道和实际信道的均方误差得到最优的导频图样.为了验证该设计方法的正确性和有效性,将其应用到长期演进(LTE)系统中,利用曲线验证最优导频的优越性.在车载测试A信道下的仿真结果表明,与应用原始LTE导频图样的系统相比,应用所设计的最优导频图样的系统具有更好的误码率性能.

A model for the mean velocity of debris flow movement based on the minimum energy dissipation principle

The geomorphic minimum energy dissipation principle is important in the development of gully evolutionary theory.The impact of debris flows on channels during movement also adheres to this theory.A minimum energy dissipation model for debris flows has been obtained from previous studies,which is derived from the flow rules of runoff along a channel under rainfall or ice-snow meltwater conditions.However,the lack of consideration for erosion characteristics has hindered a comprehensive understanding of the movement characteristics of debris flow.In this paper,the phenomenon of volume increase resulting from the entrainment along debris flow movement is considered in order to derive a model for the mean velocity,reflecting the minimum energy dissipation principle.The entire expression of the mean velocity model is determined through 38 typical glacial and rainstorm debris flow cases.To evaluate the reliability of the proposed model,we employed 164 monitoring data from 1995 to 2000 in the Jiangjia gully,Yunnan,China.The results show that the velocity calculated by the proposed model are highly correlated with those obtained from the monitoring data.Additionally,a comparison is made between the mean velocities calculated by the proposed model and those obtained from previous studies,highlighting the exceptional applicability of the proposed model.This study will contribute to reveal the movement laws of debris flow along the channel.

Quality of experience based scheduling algorithm in LTE network with various traffics

Quality of experience （ QoE ） based scheduling algorithm of long term evalution （ LTE ） network with various traffics is studied. Utility functions are adopted to estimate mean opinion score （MOS） for different traffics and a new MOS metric called normalized MOS is defined. A scheduling algorithm based on normalized MOS and greedy algorithm is proposed, aiming at maximizing the entirety MOS level of the whole users in the cell. We compare the performance of the proposed algorithm with other typical scheduling algorithms and the simulation results show that the algorithm pro- posed outperform other ones in term of QoE and fairness.

现代汉语贬抑性评价构式“破NP”研究

现代汉语中的“破NP”构式是主观性强的贬抑性评价构式,其构式义丰富,可分为直接贬抑、间接贬抑、假性贬抑、自我贬抑、反预期贬抑五种不同情况,这五种构式义与构素“NP”之间是互相选择的关系,从历时角度来看,“破NP”经过重新分析从动宾结构演变为定中结构,引发了“破”从动词到形容词的词性演变过程,最终“破”虚化为泛义形容词,“破NP”构式由此产生。在东北官话中,“破NP”构式常与方言特征鲜明的程度副词“老”结合成强贬抑性评价构式“老破NP”,“老破NP”构式又派生出“老NP”构式,属于纯粹的强贬抑性评价构式。“破NP”作为现代汉语中最常用的强贬抑性构式之一,其深层的构式义、词义演变过程及其在方言中的派生形式对于接受国际中文教育的留学生来说是很难理解的,因此我们希望通过对以上三个方面的探究修正留学生对“破NP”构式理解上的偏误,并激发留学生对中文当中其他语言现象含义及其演变过程的主动理解和探索。

技术生命周期视域下专利技术主题演化分析方法研究——以视频图像处理技术领域为例

[目的/意义]专利技术主题演化分析可以深刻揭示主题领域的技术发展脉络,如何对其进行准确挖掘对企业提高技术创新能力至关重要。[方法/过程]沿着“技术演化理论构架”→“技术生命周期划分”→“技术主题提取”→“技术主题演化分析”这一研究主线,以自建数据库为数据来源,首先,基于Logistics模型进行技术生命周期划分;然后,分别利用LDA主题模型和PCA+K-means模型进行技术主题提取,并从技术主题强度和技术主题内容两个维度进行技术主题演化分析;最后,以视频图形处理技术领域为例,验证模型的有效性和适用性。[结果/结论]研究结果表明,文章构建的智能模型可以挖掘出主题领域的热门和新兴主题,该分析方法对于认识和追溯技术主题演化规律进而厘清关键技术的发展脉络具有实际应用价值。

一种基于改进差分进化的K-Means聚类算法研究

为改进传统K-Means聚类算法中因随机选取初始聚类中心而导致聚类结果不稳定且效率低的缺点,提出一种基于改进差分进化的K-Means聚类算法(AGDE-KM)。首先,设计自适应操作算子来提升算法前期的全局搜索能力和后期的收敛速度;其次,设计多变异策略并引入权重系数,在算法的不同进化阶段发挥不同变异策略的优势,平衡算法的全局和局部搜索能力,加快算法的收敛速度;最后,提出一种基于当前种群最佳个体的高斯扰动交叉操作,为个体提供更优进化方向的同时保持种群在“维”上的多样性,避免算法陷入局部最优。将算法停止执行时输出的最优解作为初始聚类中心替代传统K-Means随机选取的聚类中心。将提出算法在UCI公共数据库中的Vowel、Iris、Glass数据集和合成数据集Jcdx上进行对比实验,误差平方和(SSE)相对于传统K-Means分别减小5.65%、19.59%、13.31%、6.1%,聚类时间分别减少83.03%、81.33%、77.47%、92.63%。实验结果表明,提出的改进算法具有更快的收敛速度和更好的寻优能力,显著提升了聚类的效果、效率和稳定性。

基于FCM和DE-GPR的指纹库构建方法

针对室内定位中指纹库构建存在人力成本高、构建效率低的问题,提出一种基于模糊均值聚类(FCM)和差分进化算法(DE)优化高斯过程回归(GPR)的指纹库构建方法。FCM-DE-GPR算法通过模糊均值聚类和隶属度阈值划分指纹库局部模型,以挖掘无线信号的局部分布特征,并采用差分进化算法对GPR的超参数寻优过程进行改进,提高GPR的拟合精度。预测阶段根据K近邻原则确定扩展点的簇归属,使用相应的局部GPR模型进行预测,完成指纹库扩展。通过仿真与实验验证,所提算法将指纹库扩展至147%的情况下,平均预测误差相较于全局GPR降低了8.1%,具有良好的指纹库扩展精度。

基于多源数据的重庆市产业功能区识别及变迁分析

基于POI数据,通过TF-IDF算法、K-means聚类算法精确识别产业功能区,深入探究重庆市中心城区2014—2021年产业功能区时空演化。结果表明:(1)重庆市中心城区休闲娱乐产业区与生活服务产业区呈集中分布;商业产业区与公共服务产业区由离散分布变为集中分布;其余产业功能区呈零散分布。(2)2014—2021年,重庆市中心城区休闲娱乐产业区、商业产业区、科教文化产业区、生活服务产业区、公共服务产业区变化较明显;房地产业区变化较小;医疗产业区变化呈先增加后减少趋势;商务服务产业区无明显变化。(3)运用混淆矩阵法对产业功能区识别结果进行精度评价,得到重庆市中心城区产业功能区总体分类精度为82.50%,Kappa系数为0.80。总体上,TF-IDF算法能够较精确地识别出产业功能区,识别结果可为研究产业功能区空间演化提供参考。

“踢蹬”考释

采用汉语史和方言词汇相结合的方法,对“踢蹬”一词进行考释。“踢”的语义演变以核心义“变化”为统领,这一核心义也贯穿“踢蹬”的语义演变过程中。在现代汉语中,“踢蹬”的使用频率虽然有所降低,但在方言中仍有保留。同时,不同方言中的词形与读音均存在一定差异。在此基础上,对方言中“踢蹬”的语义、句法、语用进行分析,并指出方言词典中存在“踢”的释义混淆等问题。

FFDEZOA优化的SCARA机器人故障数据聚类分析

针对现有聚类方法对机器人故障数据聚类时对初始点选取依赖性大、收敛速度慢且精度低等问题,提出了一种FFDEZOA算法来对KMC聚类算法进行优化。ZOA算法具有寻优能力较强,收敛速度快,且在聚类时对初始点选取依赖性小,但其有几率会陷入到局部最优解。首先针对ZOA算法的缺点,提出了自由觅食策略、非线性收敛因子及斑马进化策略等来对其进行改进,能够有效提高算法搜索范围,从而避免局部最优;进而结合FFDEZOA和KMC算法的互补迭代,既加快了算法的搜索速度,也提升了精度。在多个公开数据集上的实验表明,FFDEZOA KMC在精确度和归一化互信息的指标上均优于ZOA KMC、AO KMC、KMC和MFO KMC,具有更好的收敛性能和聚类效果。最后依据各故障特征的主成分不同,利用FFDEZOA KMC对故障数据进行了聚类,可在多种工况下对机器人进行针对性的保养和维护。

《淮南子》成语的源流演变

文章从历史维度剖析《淮南子》成语的源流演变过程,有助于汉语成语史的深入研究。以习用性、定型性、完整性和表意的双层性为成语的判定依据,统计得《淮南子》成语331条,其中源自先秦或同时期更早文献的成语211条,源于《淮南子》的成语120条。引申沿用类《淮南子》成语经直接引用、换字法、减字法、凝缩法、节录合并法、捏合法、调序法或综合法等八种方法构成,原创类则通过截取语句、改换语素或语序、添加语素、简括故事或浓缩语句等五种方式在后世被改造为成语。《淮南子》成语的演变以形式演变和语义演变为主,前者包括成语内部语素和语序上的变化,后者包括理性意义的演变和色彩意义的演变。

基于改进沙猫群算法优化CNN-BiLSTM的热负荷预测

针对传统热负荷预测精度不高、无法满足换热站及热网优化调控需求的问题,提出一种VMD-ISCSO-CNN-BiLSTM的热负荷预测模型。首先,利用变分模态分解(VMD)对原始供热负荷数据进行降噪处理,降低数据的不稳定性;其次,由K-means算法改进种群初始化,由演变机制改进寻优能力和由变异机制改进跳出局部最优能力,利用改进沙猫群算法(ISCSO)对卷积神经网络、双向长短期记忆神经网络(CNN-BiLSTM)超参数进行寻优,建立热负荷预测模型;最后通过实例进行分析。结果表明,数据降噪后模型预测精度更高,R^(2)提升1.1%;由ISCSO优化的模型比其他算法优化的模型预测效果更好,拟合度达到99.4%;VMD-ISCSO-CNN-BiLSTM的组合预测模型相较于单一模型,RMSE降低18.5%,MAE降低13.8%,R^(2)提升15.8%,并有更好的拟合度,泛化性强,满足工程实际要求。

“背书”之词义演变及其动因探析

近年来,随着社会发展,“背书”一词被赋予新的含义,使用范围扩大,使用率逐渐提高。基于词义引申等相关理论,文章探讨“背书”的词义演变情况和演变机制,认为“背书”在隐喻机制下发生两次词义演变。同时,对“背书”在语音、语法和语用等语言内部因素和大众心理、传播机制、社会环境等语言外部因素的演变动因进行探究。

“作风”源流考

现代汉语“作风”源于日语,其最初词义是“作品风格”,后来由于电影行业的发展和社会政治的变化,逐渐转移为“(思想上、工作上和生活上)表现出来的态度、行为”。“作”的词素义由原来的“作品”转为“做事”,“风”的构词能力得到提升。一些辞书中的“作风”词条释义尚有不足之处,需进一步完善,《现代汉语规范词典》应适时补充“作风”词条的示例,《近现代辞源》和《汉语大词典》应调整义项顺序,使用时间更早的书证。另外,《辞海》应补充“作风”词条,并准确释义。