Analysis on unit maximum capacity of orthogonal multiple watermarking for multimedia signals in B5G wireless communications

Beyond-5G(B5G)aims to meet the growing demands of mobile traffic and expand the communication space.Considering that intelligent applications to B5G wireless communications will involve security issues regarding user data and operational data,this paper analyzes the maximum capacity of the multi-watermarking method for multimedia signal hiding as a means of alleviating the information security problem of B5G.The multiwatermarking process employs spread transform dither modulation.During the watermarking procedure,Gram-Schmidt orthogonalization is used to obtain the multiple spreading vectors.Consequently,multiple watermarks can be simultaneously embedded into the same position of a multimedia signal.Moreover,the multiple watermarks can be extracted without affecting one another during the extraction process.We analyze the effect of the size of the spreading vector on the unit maximum capacity,and consequently derive the theoretical relationship between the size of the spreading vector and the unit maximum capacity.A number of experiments are conducted to determine the optimal parameter values for maximum robustness on the premise of high capacity and good imperceptibility.

融合多项式特征扩展与CNN-Transformer模型的锂电池SOH估计

为了提高锂离子电池健康状态(state of health,SOH)估计的精确度,本研究结合卷积神经网络(convolutional neural networks,CNN)强大的局部特征提取能力和Transformer的序列处理能力,提出了基于多项式特征扩展的CNN-Transformer融合模型。该方法提取了与电池容量高度相关的增量容量(incremental capacity,IC)曲线峰值、IC曲线对应电压、面积及充电时间作为健康因子,然后将其进行多项式扩展,增加融合模型对输入特征的非线性处理能力。引入主成分分析法(principal component analysis,PCA)对特征空间进行降维,有利于捕获数据有效信息,减少模型训练时间。采用美国国家宇航局(National Aeronautics and Space Administration,NASA)数据集和马里兰大学数据集,通过加入多项式特征前后的CNN-Transformer模型对比、加入多项式特征的CNN-Transformer模型和单一模型算法对比,验证了加入多项式特征的CNN-Transformer融合算法的有效性和精确度,结果表明提出模型的SOH估计精度相较于未加入多项式特征的CNN-Transformer模型,对于B0005、B0006、B0007、B0018数据集分别提高了38.71%、50.28%、4.71%、17.58%。

Review on Capacity Optimization of Traction Transformer for High-Speed Railway

In electrified railways,traction load not only fluctuates between peaks and valleys,but also has a situation of low utilization rate of average load throughout the day and short overload.The traction transformer selects the capacity with the peak load as the demand boundary,which will cause the capacity utilization rate to be low and even lead to the economic decline of the traction power supply system.This article summarizes the existing configuration methods for capacity optimization of traction transformer.Then under the conditions of energy storage and new energy access to traction power supply system,the three aspects are described as follows.Firstly,the energy storage device is connected to the system,which can pull the capacity of traction transformer to achieve peak shifting and valley filling.Then,the possibility of integrated configuration of new energy and traction power supply system to optimize the capacity of traction transformer and the methods of optimal configuration of traction transformer capacity by using new energy such as wind and light are summarized.Finally,this paper discusses the current structure of new energy access to traction power supply system,and it looks forward to the feasibility of new energy access to traction power supply system cooperating with energy storage devices to optimize the capacity of traction transformer.

Capacity Openness Boosts Digitization Transformation of Telecom Operators

With the emergence of digital transformation success stories,more and more enterprises are launching digital solutions to improve business efficiency or achieve optimal revenue growth.The traditional communication market tends to be saturated,and the digital transformation of telecom operators is imminent.This article combining the development trend of telecom operators’product business and the application situation of the pilot summarizes the innovative application categories that telecom operators continue to launch based on their own advantages and in response to the needs of the industry.This article focuses on the transformation of security capabilities in communication services,big data,Internet of Things,artificial intelligence,unified authentication and network information security,and deeply analyzes the business characteristics and application modes from the aspects of resource integration,open platform construction,new connection construction,and innovative business development.This article puts forward suggestions for the security development of telecom operators,and provides basic research content for the subsequent research on the innovative application of telecom operators’capability openness.

Economic Transformation Capacities and Developmental Countermeasures of Coal-resource-based Counties of China

In China,the economic systems of many small-scale resource-based regions are confronted with realizing sustainable development through economic transformation. This paper,taking 37 coal-resource-based counties in China as objects,evaluates the economic transformation capacities of the counties by principal component analysis (PCA). Based on the comprehensive principal component values of >1,0–1 and <0,the economic transformation capacities of the counties are classified into strong,common and weak grades. Then,the paper proposes the developmental countermeasures according to different transformation capacities. For the counties with strong transformation capacities,it is crucial to make scientific positioning and rationally exploite resources in view of the developing characteristics and modes of those counties; as for the counties with common transformation capacities,the preparation and perfection of basic transformation conditions are still important aspects; as for the counties with weak transformation capacities,shifting from ″passive transfromation″ to ″active transformation″ in light of resources conditions is necessary.

Key Techniques of High-voltage and Large-capacity Series Hybrid Active Power Filters

基于基波磁通补偿的串联混合型有源电力滤波器（active power filter,APF）应用于高电压、大容量的谐波抑制场合时,受变压器励磁支路谐波电压的影响,逆变器不能等效为基波电流源,其输出电流将含有大量的谐波,从而影响滤波效果。以逆变器为核心,推导出在励磁支路谐波压降影响下的串联变压器的谐波等效阻抗。并以此为基础,从理论上分析励磁电感和变比对串联变压器谐波等效阻抗和APF滤波效果的影响。仿真结果验证了理论分析的正确性。最后,针对广东某厂10kV、1MVA电力负荷,研制一套基于基波磁通补偿的串联混合型有源滤波器工程样机,取得非常好的滤波效果。

Characteristic of specific heat capacity of NiTi alloy phases

The specific heat capacity of NiTi alloy at constant pressure using MDSC (Modulated differential scanning calorimeter) was determined. It was found that the variation tendencies of the specific heat capacity for different phases are different. The fitting equations of the specific heat capacity for martensite and austenite phases were presented. Then, a reason, based on thermodynamic point of view, was proposed to explain the difference of the specific heat capacity between martensitic and austenitic phases. Finally, compared with the specific heat capacity of pure Ni and Ti, it was found that the specific heat capacity of NiTi alloy is inherent to that of pure Ti. When the specific heat capacity of NiTi alloy is calculated by Neuman Kopp, in the temperature region of phase transformation and the temperature higher than 400 K, the results are not desirable.[

Non-Euclidean Geometry and Regulated Characteristics of Limited Capacity Power Supply

The restriction of load power, two-valued regulation characteristic, and interference of several loads are observed in power supply systems with a limited capacity of voltage sources. In this paper, the definition of regime in an invariant form through different parameters, of changes of transformation ratio and voltage load is grounded for these circuits with two loads. The approach for interpretation of changes or ＂kinematics＂ of load regime is presented by using the conformal and hyperbolic plane. To simplify the task and reveal the basic moments of influence of the limited source power, the static regulation characteristics and idealized models of voltage converters are considered. Geometrical interpretation of a simplified model of multichannel power supply system allows basing the definition of operating regime parameters. Results can be useful for electric circuit theory education and for voltage coordinated control of given loads. Non-Euclidean geometry is a new mathematical apparatus in the electric circuit theory, adequately interprets ＂kinematics＂ of circuit, and provides a validation for the introduction and definition of the proposed concepts. From the methodological point, the presented approach is applied for a long time in other scientific domains, as mechanics and biology.

基于温升特性的强迫导向油循环风冷结构变压器负荷能力评估

针对强迫导向油循环风冷(oir directrd air forced,ODAF)结构变压器负荷能力受温升约束影响的问题,提出了3种负荷类型情况下变压器负荷能力评估方法。首先,考虑风扇与油泵的运行状态以及油粘度变化对热阻的影响等因素,基于热电类比法建立了变压器热路模型,以计算绕组热点与顶部油温度;其次,采用粒子群优化(particle swarm optimization,PSO)算法拟合热路模型参数,并基于2台不同型号变压器的运行数据,对热路模型的计算精度与拟合参数适用性进行有效性验证;最后,参考GB/T1094.7负载导则给出的温升限值,基于温升特性提出了负荷能力评估模型。分析结果表明,该研究所提热路模型计算热点温度的误差不大于2.35℃,在工程允许范围内;正常周期性负荷下当环境温度低于1℃时,关闭1组子散热器后仍满足温升约束。

数字经济发展降低了企业财务风险吗?——基于吸收能力与生命周期的视角分析

使用2011—2020年沪深两市A股上市公司的数据,在运用熵权法构建数字经济指数的基础上,实证检验数字经济发展对企业财务风险的影响以及内在机制。研究发现:(1)数字经济对企业财务风险具有显著的抑制作用,吸收能力在数字经济抑制企业财务风险的过程中具有部分中介效应。(2)处在生命周期不同阶段的企业,数字经济的发展对企业财务风险的影响也不相同。对于成长型和成熟型企业,数字经济的发展对抑制企业财务风险具有显著作用,且吸收能力具有中介效应;对于陷入衰退期的企业,数字经济的发展对降低公司的财务风险没有显著影响,且吸收能力不具有中介效应。(3)数字经济的有效性需要企业内部基本条件的支持。当企业的数字转型良好时,数字经济在遏制企业财务风险方面的作用更加明显。总的来说,数字经济的发展有利于企业提高吸收能力,降低财务风险。研究揭示了财务风险产生的原因,以及数字经济在降低财务风险方面各种差异的作用和机制,为缓解企业财务风险提供了可靠的实证依据和政策启示,具有重要的现实意义。

基于自适应小波变换与HHT的混合储能容量配置

混合储能系统能有效缓解风电输出功率强波动性与随机性造成电网频率不稳定问题。本文以蓄电池和超级电容组成的混合储能系统为研究对象,提出了一种混合储能容量配置方法。该方法首先采用自适应小波变换对风电输出功率进行功率一次分配,得到满足条件的并网功率和储能功率。然后采用HHT变换对储能功率进行分解,得到一系列波动功率分量以及各分量的瞬时频率。再根据瞬时频率确定分界频率,将高于分界频率的功率分量分配给超级电容,剩余的功率分量分配给蓄电池。最后根据蓄电池与超级电容各自的储能功率,对储能系统的额定容量与额定功率进行配置。该仿真结果表明,本文采用自适应小波变换与HHT变换能够有效地将风电输出功率进行分解,实现风电输出功率的平抑与混合储能系统的容量与功率配置。

能源转型及“双碳”目标背景下全球炼油行业发展新态势与前景展望

2023年,全球炼化项目建设稳步推进,炼油重心继续东移;全球新增炼油能力8617.5万吨/年,高于上年新增量,总炼油能力提升至51.8亿吨/年。全球原油加工量合计约8240万桶/日,恢复至疫情前水平,装置开工率持续回升,炼油毛利继续保持历史较高水平。炼油行业加快结构调整和转型升级,欧美炼油商加快投资生物燃料生产,中东非洲地区以新建项目推动炼油业转型升级。炼油技术在劣质重油加工、清洁燃料生产、炼油向化工转型等方面取得持续进展,原油直接制化学品技术成为重点方向。2024年全球有望新增炼油能力近1亿吨,全球炼化项目在2030年前仍将继续保持增长,增长中心集中在亚太和中东地区;2024年全球炼厂原油加工量同比增长约100万桶/日,增量主要来自中国、中东、非洲地区,世界炼油毛利有望维持较好水平;2030年前炼油结构调整和转型升级仍是炼油业发展的主基调,新兴经济体炼油行业将继续加快转型升级和绿色智能化发展进程。

数字化转型、动态能力与企业全要素生产率——基于中国制造业上市公司的经验证据

数字技术与传统产业的深度融合已逐渐成为推动中国经济可持续发展的新动能,企业作为宏观经济中的微观主体,其创新发展水平与宏观经济结构优化、经济发展方式转型升级密切相关,企业如何利用数字技术进行转型升级来进一步提升自身全要素生产率,具有较为深刻的现实意义和实用价值。基于动态能力理论,以2016-2021年沪深A股上市制造企业为样本,实证考察数字化转型对企业全要素生产率的影响及其作用机制。研究发现:其一,数字化转型与企业全要素生产率显著正相关,在考虑内生性问题和稳定性检验后,研究结论依旧成立。其二,作用机制结果表明,实施数字化转型提高了企业的吸收能力、创新能力和适应能力,进而提升了企业全要素生产率,在对中介变量进行Sobel检验后,研究结论依旧稳健。其中,吸收能力的作用效应最强,创新能力次之,适应能力最弱。其三,通过对企业所有制、规模大小及企业所处地区进行异质性分析后发现,相比较于非国有企业、中小企业及中西部地区企业而言,数字化转型对国有企业、大型企业及东部地区企业全要素生产率的提升效应更强。本研究拓展了数字化转型相关理论,对加快数字经济发展、深化供给侧结构性改革、加快新旧动能转换、助力企业早日实现高质量发展具有重要启示。

基于多通道的彩色图像多重水印算法

针对多重水印技术如何确定最优的嵌入区域,以实现多个水印之间的权衡问题,提出一种基于多通道嵌入的彩色图像多重水印算法。当嵌入水印时,选择在彩色图像R、G、B 3个通道嵌入不同的水印图像,目的是嵌入更多的水印信息。通过提升小波变换(LWT)和非下采样剪切波变换(NSST)提取宿主图像每个通道中的方向性特征,确定水印的嵌入位置,以提高对常规攻击和几何攻击的鲁棒性。通过将加密的水印有效信息嵌入到具有良好稳定性的奇异值矩阵中,保证水印的提取效果。实验结果表明,嵌入水印后的图像峰值信噪比(PSNR)在43 dB以上,所提算法具备良好的不可见性,对嵌入水印后的图像进行高强度的旋转、滤波、剪切等攻击,提取水印的归一化系数(NC)值在0.95以上,其中,滤波攻击对应的NC值可以达到0.99以上,水印信息提取完整、清晰可辨,表现出较强的鲁棒性。同时,该算法可以1次嵌入3个水印图像,具有更高的嵌入容量。因此,与现有的多重水印算法相比,该算法的不可见性、鲁棒性和嵌入容量均有较大的提升。

环境承载力中介下森林转型赋能区域生态宜居——作用路径与效应识别

基于中国1999—2018年4次森林资源清查结果及相关统计数据,对中国31个省域(不含港澳台地区)的森林转型指数、环境承载力和生态宜居水平进行测评,然后借助中介效应模型探索森林转型赋能区域生态宜居的作用路径,并测度环境承载力对森林转型赋能区域生态宜居水平的中介效应。结果显示:1999—2018年中国森林转型指数整体呈现稳中有升的发展态势,但不同地区之间水平差异比较明显,西南、东北地区森林转型效果最为显著;中国环境承载力的“U型”曲线演变特征明显,其中西南、华南、华东地区环境承载力较强,华东、华中、华南、华北地区环境承载力在回升阶段表现突出,东北、西南和西北地区在经济快速发展时期,环境承载力呈现下降趋势,突显出资源环境系统脆弱性;中国生态宜居水平总体呈现波动上升态势,其中西南、华北、华东地区上升态势最为明显;环境承载力在森林转型对区域生态宜居水平影响中具有中介作用,森林转型通过提升环境承载力部分解释了其对区域生态宜居水平的促进作用。

数字化转型对农业企业可持续绩效影响研究——来自中国农业上市公司的实证

本文从资源基础观出发,基于2008~2021年沪深A股农业上市公司数据,利用SAS构建农业企业数字化转型指标,采用企业经济绩效和环境绩效相结合的方式更加全面地衡量农业企业可持续绩效,实证检验了数字化转型对农业企业可持续绩效的影响。研究发现,数字化转型可以显著提升农业企业可持续绩效,正向影响农业企业经济绩效,负向影响环境绩效,经过稳健性检验后,实证结果仍然保持一致;吸收能力并不能强化数字化转型对农业企业可持续绩效的正向影响,这可能与目前农业企业吸收能力普遍较低相关。进一步分析发现,国有农业企业和中西部地区农业企业进行数字化转型对可持续绩效的提升更显著,大型农业企业实施数字化转型更能带来可持续绩效的提升,处于成长期的农业企业进行数字化转型对可持续绩效的提升更明显。本文研究结果丰富了资源基础观,对农业企业在数字经济背景下实现可持续发展具有重要的现实指导意义。

中小制造企业数字平台能力对其数字化转型的影响研究

为探索中小制造企业如何依托数字平台能力提升数字化转型绩效,基于动态能力理论,以398家制造业中小企业为研究样本,运用层次回归方法,探究数字平台能力对其数字化转型绩效的影响机制,并揭示吸收能力和组织敏捷性在此过程中的链式中介作用。研究表明:中小制造企业的平台整合能力与平台重构能力作为其数字平台能力的两个维度,均对数字化转型绩效具有显著正向影响;吸收能力和组织敏捷性分别在中小制造企业平台整合能力、平台重构能力与其数字化转型绩效的关系中起到部分中介效应,并共同发挥链式中介作用。

领军企业数字化转型提升同行非领军企业的创新产出了吗?

基于2012—2021年沪深A股市场各行业中非领军企业数据,考察行业领军企业数字化转型的溢出效应及其对同行非领军企业高质量发展的赋能效应。研究发现:(1)领军企业数字化转型显著提升了同行非领军企业的创新产出,这一效果主要通过“引领带动效应”和“资源溢出效应”两条路径实现;(2)企业特质及行业特征差异均会显著调节领军企业数字化转型溢出效应的强度;(3)领军企业数字化转型在提升同行非领军企业的创新产出后,进一步赋能同行非领军企业的高质量发展。结论为我国政府创新驱动发展战略的落地以及通过数字化转型推动企业创新和行业高质量发展提供了理论指导和实践启示。

降低青海油田尕北、英东区块供配电系统能耗方法研究

根据国家节能降碳的要求,青海油田公司对所属尕北、英东区块供配电线路运行情况进行测试,测试中发现供配电系统存在变压器能效等级及负载率低、线路功率因数及网损率不合格等问题,造成供配电系统能耗较高。通过对线路及变压器运行进行现场数据采集,分析原因,对各线路存在问题提出整改方案、确定改造方向,通过采用无功补偿、优化运行等措施,预计年可实现节约电量185.06×10^(4) kWh,折合226.88 tce,减少二氧化碳排放557.38 t。

应急物资生产企业产能优化策略研究

公共卫生事件对社会和企业生产经营带来了巨大挑战。企业在突发公共卫生事件后应急物资的提供中占有举足轻重的地位,高效的政企协同有利于快速维护社会稳定,而危机后过剩产能的转型更值得被关注。企业层面应致力于创新的需求分析、人才培养与匹配、精准的供应链培养等方面,顺利熨平产能波动曲线。政府层面应致力于建立完备的“24小时经济圈”内产业链,并建立数字化供应链、信息链,协助企业获取准确产销信息。