REDUCING THE PEAK-TO-AVERAGE POWER RATIO OF OFDM SYSTEM WITH LOW COMPLEXITY

This paper proposes a companding scheme, where small signals are enlarged and large signals are reduced, to reduce the Peak-to-Average Power Ratio(PAPR). Computer simulation results show that the proposed technique has two advantages at least when compared with the conventional methods such as partial transmit sequence, selective mapping and the previous companding. First, it gets better PAPR performances with a lower complexity. Second, the scheme achieves greater performances gain with hardly any damnification of OFDM signals in some degree.

A Novel Peak-to-Average Power Ratio Reduction Scheme via Tone Reservation in OFDM Systems

In this paper, a novel signal-to-clipping noise ratio and least squares approximation tone reservation scheme(SCR-LSA TR) is proposed to reduce the peak-to-average power ratio for orthogonal frequency division multiplexing systems. During the SCR procedure, only the element with the maximal amplitude is picked for processing, which not only decreases the algorithm complexity, but also helps to overcome the BER deterioration. With the LSA method, the amplitude of the peak-cancelling signals can approximate to that of the original clipping noise as much as possible. Through the combination of the optimization factor in the LSA method, the classic SCR method can achieve better PAPR reduction with faster convergence. Simulation results show that the proposed SCR-LSA TR scheme has less in-band distortion and smaller out-of-band spectral radiation. The BER of the proposed scheme shows a better performance especially under the 16-QAM over the additive white Gaussian noise channel.

Simulation on Peak-to-Average Power Ratio for Orthogonal Frequency Division Multiplexing

Clipping is a simple and convenient PAPR （peak-to-average power ratio） reduction method for high speed OFDM （orthogonal frequency division multiplexing） communication system. In this paper, we propose a new PAPR reduction method for Wireless-MAN（metropolitan area network）-OFDM system based on IEEE 802.16, which is over-sampling clipping arithmetic. Simulation and performance of the over-samples clipping＇s PAPR reduction capability, BER effect is given. The simulation indicates that the PAPR of at least 99.9% OFDM symbol is below 6dB after 2 Nyquist rate clipping, and the performance of BER has 1dB SNR（signal noise ratio） loss. The results prove that this method has better capacity to reducing PAPR. So it can be well used in WMAN-OFDM system.

COMPLEMENT BLOCK CODING SCHEME FOR REDUCING PEAK-TO-AVERAGE POWER RATIO OF OFDM SYSTEMS

A new scheme termed as Complement Block Coding (CBC) technique is proposed to reduce the Peak-to-Average Power Ratio (PAPR) of OFDM signals. Utilizing the complement bits which are added to the original information bits,this method can effectively reduce the PAPR of OFDM systems with random frame size N and the coding rate R ≤ (N - k)/N, where kis a positive integer and k ≤ N/2. The performance results obtained with CBC are given and compared with that of some well known schemes, such as Simple Block Coding (SBC), Modified Simple Block Coding (MSBC) and Simple Odd Parity Code (SOPC) for the same purpose. The results show that, at the same coding rate 3/4, the CBC can achieve almost the same performance as SBC, MSBC, but with lower complexity, and that the same performance can be obtained with higher coding rate by using CBC. At the same coding rate (N - 1)/N, the PAPR reduction of CBC is almost the twice as that of SOPC when N ≥ 16. Further more, the PAPR reductions with coding rate (N - 1)/N are almost the same as that with coding rate less than (N - 1)/N,so the proposed scheme CBC is more suitable for the large frame size with high coding rate and can provide error detection.

Peak-to-average power ratio reduction using selective mapping with unequal power distribution

A new approach for peak-to-average power ratio (PAPR) reduction in orthogonal frequency division multiplexing (OFDM) systems was proposed.This approach is based on assigning powers to the different subcarriers of OFDM using an unequal power distribution strategy.In addition,a reduced complexity selective mapping (RC-SLM) scheme was proposed.The proposed scheme is based on partitioning the frequency domain symbol sequence into several sub-blocks,and then each sub-block is multiplied by different phase sequences whose length is shorter than that used in the conventional SLM scheme.Then,a kind of low complexity conversions is used to replace the IFFT blocks.The performance of the proposed RC-SLM scheme along with the new approach was studied with computer simulation.The obtained results show that the proposed RC-SLM scheme is able to achieve the lowest computational complexity when compared with other low complexity schemes proposed in the literature while at the same time improves the PAPR reduction performance by about 0.3 dB.

数据库设计工具的选择——Erwin,Power Designer,Rational Rose

随着数据库设计的需要,越来越多的CASE工具出现在我们的视野里,如何选择适合自己的工具就成了当务之急,下面对几种常用的工具Erwin,Power Designer,Rational Rose做以下对比。

Asymmetry Is Itself Symmetry： The Dilemma of Rationality-Power Relationship

Bent Flyvbjerg＇s research reveals a context dependent asymmetrical relationship between rationality and power, causing the so-called illegitimate rationalization to affect the decision-making process. This paper explores the nature of relationship between rationality and power by following Russell＇s philosophy and logic. The paper demonstrates how a symmetrical relationship may be transformed into an asymmetrical relation. Any study suggesting asymmetrical relationship between rationality and power may not be able to explain the relational dynamics of the two terms, By questioning the rationality-power asymmetrical relationship, the paper stresses the need to define the degree of asymmetry between rationality and power. The paper suggests a need for better interpretation and relational understanding of rationality-power relations for effective decision-making.

Cold wave caused power supply reducing and rationing

Because of the amalgamation of coal resourcesin Shanxi Province in 2009, coal production centermoved westward in China. The coal outputs of InnerMongolia and Shaanxi got higher. From January

中国式现代化理论的标识性范畴与体系化构建

中国式现代化范畴既有从探索提出到形成确立的逻辑演进过程,也有从简单范畴到范畴体系的逻辑展开过程。中国式现代化是新时代党的理论创新的标识性范畴,但作为一个科学理论体系,中国式现代化理论自身也包含着一系列标识性范畴,这些范畴揭示了中国式现代化的内涵、特征和本质,使中国式现代化更加清晰、科学、可感可行。中国式现代化理论的标识性范畴为构建中国式现代化理论的科学体系,提炼中国式现代化理论的基本原理,提升中国式现代化理论的话语说服力和影响力,进而推进中国式现代化理论的体系化、学理化,奠定了坚实的概念基石和理论基础。提炼并阐明中国式现代化理论的标识性范畴,是构建具有学理性的中国式现代化理论体系的基础工作和必要环节。

在“行政效率”与“地方文化网络”之间:乡镇基层治理的综合情理与实践智慧

“情理”在中国基层社会治理中有着举足轻重的结构位置,但其具体实践依然有进一步研究的空间。浙北W镇综合行政执法分局的基层实践,根据基层行政执法部门的行动指向和实际控制权两个维度,采取了秉持人文关怀、外借权威、联合避责等行动策略,以应对治理场景下的工作压力和提高治理效果。执法部门的“情理”运作有着深刻的实践逻辑,即在提升政府治理效能、符合社会期待、维持部门组织自主性、降低治理风险性等多维的情理维度之间寻求平衡,这是“行政效率”与“地方文化网络”动态交互而成的实践智慧。

经济法的立法路径审视及其改革

立法是法治的基础,这对以立法主体主动建构规则为重要特征的经济法尤为重要。经过多年改革,当前我国的经济立法在立法动因上体现出政策驱动性和实践回应性,在立法体系上体现出横向协同性和纵向续造性,在立法模式上体现出授权性和试验性,促进了经济立法的发展和进步。但同时,也存在对多元立法目标平衡不足、立法权配置的整合与统筹不力、对立法合理性和立法效果评估不够重视等问题。对此,应以规则合理性为标准,进一步深化经济法立法路径的改革,重点加强立法主体的说明解释机制,促进经济立法权的合理分配与整合,致力于立法合理性最大化,并构建和完善立法后评估制度。

资源保存理论视域下我国职业足球发展的理性审视

中国职业足球发展30年,出现了诸多社会性问题,给中国体育和中国足球带来破坏性影响。为积极探索新发展阶段我国职业足球面临的新问题与新挑战,运用文献研究、逻辑分析、案例研究等方法对我国职业足球发展问题进行分析。研究发现:现阶段,我国职业足球发展存在职业足球管理主体权限不清、责任不明,职业足球发展监管缺位,职业足球从业者道德迷失,职业俱乐部价值目标迷离等失范问题。在资源保存理论视域下审视这些问题,结合加快建设体育强国的背景,提出全面振兴策略:厘清我国职业足球现有资源存量,推动不同资源间的交互作用;结合我国职业足球资源动态过程,形成资源波动上的螺旋机制;合理促进职业足球资源人际流动,实现振兴发展上的群体效能。

数字时代下的算法理性与算法权力——对算法权力中人的处境的再思考

在霍克海默与阿多诺的笔下,作为一种“工具一般”的理性成为符合资本主义异化逻辑中对主体的压制性力量。伴随着人工智能、元宇宙等数字技术的飞速发展,需要对数字时代下的“工具一般”进行重新思考。从历史唯物主义的角度出发,在马克思所处的产业资本主义时期,工人被当作机器的有机形式围绕着机器的逻辑运转;而在鲍德里亚的“物体系”当中,人们进行消费的不再是商品的功能性,而是一种符号价值。也就是说,所有人都被商品物的符号—象征法则所支配;算法成为数字资本主义的权力载体,在算法理性的支配下,所有人都以一种数字的“非人”状态被裹挟进数字资本的生产之中。从无意识的工具、无主体的统治以及再划分的边界这三个层面重新理解人与算法权力的关系具有较强的现实意义。

基于改进ARIMA的新能源发电短期动态调度模型

针对地区电网因运行方式变更导致新能源上网通道受限,而采取等比例限电方法造成新能源利用率较低的问题,文章提出一种基于改进ARIMA算法的新能源电厂上网负荷短期动态调度模型。该模型首先根据光伏发电的不连续性、风力新能源发电的季节性、随机性、间歇性等特点,利用改进的维纳滤波算法通过自适应阈值变化从历史负荷中提取有效的负荷规律;再利用伊藤过程和乘积方法对ARIMA进行改进,即通过改进时序的方法提高新能源负荷不连续时的准确性;最后通过ADMM对新能源电厂上网负荷进行动态调度。实验结果表明:文章的方法预测光伏准确率相比于ARIMA、LSTM平均提高了29.1%、22%,风电预测准确率提高了17.3%、5.6%;新能源利用率相比于传统方法提高了10%。

学术权威的失范与纠偏

“权威”这种原本在规则下的产物在当下学术资本主义的逻辑下已经存在凌驾于规则之上的情况,其逐步构建了一种以学术权威为核心的秩序体。这种“失范”的学术权威已经不再能够以一种学术共同体的规范呈现,其对学术的正常发展构成了威胁,如造成了学术权威的垄断、导致了学术理性的压抑、影响了学术秩序的运转。为此探究当下学术权威的“失范”行为并进行纠偏,使学术权威能够规范地运行、理性地运行,找回学术权威失落的“本真”是应有之义。

Rational统一过程在开发电网仿真系统中的应用

阐述了Rational统一过程的基本特征和工作流,且将RUP引入电网仿真系统的开发过程,建立了电网仿真系统基于RUP的用例模型和系统构架,给出了电网仿真系统的迭代实现过程,并对RUP进行了总结。

如何形成有价值的课程知识

在课程研究领域,与“什么知识最有价值”“谁的知识最有价值”不同,“有价值的知识如何形成”这一提问方式摒弃了传统课程知识观对知识建构主体的理性或权力身份的探讨,强调“主体去中心化”,即将课程知识和权力放到历史的脉络中检视,追溯主体所在的论述空间的构建路径。“有价值的知识如何形成”这一问题旨在揭示课程知识的实质、课程知识的建构以及课程知识的自然化与常态化过程,描述了课程知识作为限定并传达社会规则的物质性实践的本质属性、由社会和历史双重建构的生成过程以及课程知识所构筑的话语空间对儿童的区隔与规训。积极探索有价值的课程知识形成的多元理路,可借助“碎片化”的思考工具、“当下历史”的研究范式、“社会知识论”的研究方法论,在强化人们对课程知识的警惕与反思的基础上,为人们提供突破课程知识圈围的合法性依据与具体研究方法论,使教育研究者乃至师生有意识,也有能力主动探寻课程知识的多种可能。

基于VMD-TCN-LSTM模型的短期光伏功率预测

针对光伏发电易受气象因素影响导致发电功率不稳定问题,提出了一种基于变分模态分解(Variational Modal Decomposition, VMD)、时域卷积网络(Temporal Convolutional Network, TCN)和长短期记忆神经网络(Long Short Term Memory Network, LSTM)的短期光伏功率预测模型,以准确预测其发电功率,给电力系统的调度规划提供参考。上述模型首先使用VMD对光伏发电功率数据进行分解,得到多个不同频率的分量,再将光伏发电功率数据、分量数据以及气象数据输入TCN-LSTM,以对数据特征进行深度挖掘,经多次迭代最终输出预测结果。通过实验验证,上述模型的均方误差、平均绝对误差等指标有所提升,具有更高的预测精度。

家朋抽水蓄能电站取水影响及用水合理性分析

家朋抽水蓄能电站是国家能源局批复的安徽省新建抽水蓄能电站推荐站点之一,建成后可显著提升安徽电网的供电质量,而对其取用水方案进行水资源论证是建设过程中的必要环节之一。本文通过分析该电站在施工期、蓄水期及运行期的取水过程对区域水资源量、坝下河道及其他用水户的影响,论证了其取水合理性;通过计算其单位装机取水量及补水率等指标,并与地区水文气候条件及装机容量相近的同类电站进行对比,进一步分析了其用水合理性。结果表明:在落实必要的水资源保护及经济补偿措施后,电站取水对于区域水资源的影响可以得到有效控制,其各项用水指标也与同类工程基本相当。综上,该电站的取用水方案是合理且可行的。

新能源合理利用率研究

加快构建新型电力系统,是电力领域服务“双碳”目标、推动生态文明建设的重要举措。新能源合理消纳利用是构建新型电力系统的关键,本文提出以新能源合理收益、消纳责任权重、调节能力提升措施发展潜力等为约束,以综合考虑新能源开发运行成本和系统消纳成本等因素的系统综合成本最小为目标的新能源合理利用率优化方法,可以得到新能源合理利用率及相应的新能源规模和调节能力提升措施。以云南省为例,通过算例分析,验证了方法的合理性和可行性。