基于信息生态理论的政法事件微博舆情传播规律研究

[目的/意义]在以政务微博为代表的新媒体技术不断发展的背景下,政法事件微博舆情传播成为政法机关面临的新问题。对政法微博舆情传播进行研究,有助于剖析微博舆情传播的信息生态学规律。[方法/过程]基于信息生态理论构建政法微博舆情生态系统,以聊城于欢案政法事件为研究实例,将新浪微博舆情信息作为研究对象,对系统内的信息主体、信息环境、信息3个因子的传播和演化过程进行分析。[结果/结论]研究结果表明,主体因子中用户粉丝数和关注数均符合幂率分布且呈断尾分布特征;信息因子特征量符合指数分布;环境因子特征量具有长尾分布特征,政法微博舆情传播符合信息生态学的互生再生规律、动态平衡、协同进化规律。文章的研究对政法机关舆情监管部门把握微博舆情传播规律及舆情控制具有一定的参考性作用。     

Influence of hydrodynamics on the growth kinetics of glass-adhering Pseudomonas putida cells through a parallel plate flow chamber

The objective of this work was to investigate the influence of hydrodynamics on the growth kinetics of surface-adhering Pseudomonas putida cells. The results showed in particular that under non substrate-limiting conditions, the early step of bacterial apparent growth rate is lower than those measured with suspended cells. Contrary to previously cited authors which explain this behavior to the different adhesive properties of the “daughter”-cells (which makes more probable the detachment of these daughter-cells), in our experimental conditions, that explanation does not hold and we show a clear dependence of growth kinetics with flow conditions, due to the formation of boundary layer concentration at low Reynolds number. These results revealed that using Monod law in the modeling of biofilm growth in fixed-biomass processes should be performed with care.     

基于HDL的PPM调制系统的设计

本文用VHDL语言设计了PPM的传输系统,实现了传输速率为512kb／s的数字信号调制。结果表明,PPM基带调制系统正确工作。     

移动社交APP用户转移行为的影响因素研究

[目的/意义] 移动社交APP发展迅速,但各类产品之间的功能较为相似,相互之间替代性较高,因此防止用户转移对于社交APP来说至关重要。基于PPM（推-拉-锚）模型,研究了社交APP用户的转移行为。[方法/过程] 对收集的322份有效问卷采用SEM进行分析。[结果/结论] 研究结果表明,系统质量不满意度、服务质量不满意度、社会认同和社会交互等因素正向影响用户的转移意向,转移成本负向影响转移意向。研究结果启示社交APP需要采取措施阻止用户转移,从而实现用户保持,获取竞争优势。     

Theory for incompressible fluid turbulence

The functional integral representation for the space-time Hopf characteristic functional associated with boundary-free incompressible fluid turbulence is evaluated accurately to order R^-2, where R is the dimensionless Reynolds number in the theory. This work extends the results obtained previously for C-dominant turbulence to the regime of experimentally accessible large Reynolds numbers. We obtain a characteristic functional of non-Gaussian form as an asymptotically exact solution to the theory for large values of R. Two-point and three-point velocity correlation tensors of physical interest are derived from the characteristic functional.     

学术微信公众号用户持续使用意愿影响因素研究

[目的/意义] 探讨学术微信公众号用户持续使用意愿的影响因素,期望促进学术微信公众号的健康和可持续发展。[方法/过程] 基于期望确认模型（ECM）和PPM模型,构建了学术微信公众号用户持续使用意愿的影响因素模型,并通过问卷搜集300份有效样本数据,采用结构方程模型分析数据。[结果/结论] 结果表明,用户对学术微信公众号的满意度是影响用户持续使用意愿的主要因素;感知有用性正向影响满意度,间接影响用户持续使用意愿;期望确认正向显著影响感知有用性和满意感,间接影响用户持续使用意愿。与此同时,感知娱乐、信息质量和服务质量正向显著影响期望确认,间接影响感知有用、满意度、持续使用意愿。此外,转换成本、替代者吸引对持续使用意愿影响不显著。最后提出了相应的建议。     

基于DEA模型的网络舆情政府应对效果研究

【目的/意义】当前网络舆情事件日渐增多,能否有效应对成为评价政府执政能力的新指标。为了探究网络 舆情事件内在差异,总结我国网络舆情传播的客观规律,为政府在网络舆情中及时准确地采取合理的应对措施提 供科学的参考依据。【目的/意义】本文选取2017至2020年间的15件热点网络舆情事件,结合DEA模型建立了舆情 事件政府应对评价指标体系,并进行了实证研究。【结果/结论】研究发现,模型可以给出舆情事件中政府应对的效 率值,直观反映了政府舆情应对的有效性,还可以进一步明确政府应对不当的环节,政府据此可以设置改进的意 见。【创新/局限】本文拟定的下一步研究工作是建立更加精确的指标体系,以期对舆情事件中政府应对的影响因素 作出更加深入的思考。局限性在于评价体系中的某些指标只能采用德尔菲法进行赋值,考虑到主观因素难以进行 精确量化,受到时间与条件的限制较大。     

光伏系统典型MPPT控制方法比较研究

太阳能光伏组件是非稳定电源,为有效利用太阳能,必须对其进行最大功率点跟踪（MPPT）。论文分析了光伏发电MPPT原理,提出一种基于占空比扰动的MPPT控制方法,在Matlab中建立扰动观察法和增量电导法仿真模型,仿真结果显示两者均能实现最大功率点跟踪,增量电导法性能要明显优于扰动观察法,但其硬件要求高。研究为光伏发电MPPT算法选择提供了参考,当系统精度要求高,硬件能够满足控制要求,可以选择增量电导法,否则应考虑扰动观察法。     

Re及Ma对边界层的影响分析

本文分析了跨音速流中Ma及Re对边界层的影响,结论为Ma的增加使得激波强度增加,流向逆压梯度增加,边界层厚度增加较快,容易分离;Re的增加有两个效应：一是使得转捩提前,二是使得边界层变薄。R e增加使得激波后机翼表面压力降低,升力损失减小。跨音速范围内,Re对边界层与外流的干扰十分显著。     

The coefficient of resistance as a function of Reynolds number for solids of various shapes

The purpose of the present article is twofold. First it is an attempt to show the usefulness of the degree of true sphericity as an expression for shape of rock particles. Second it is intended as a background for a new, analytical, sedimentographic method to be given in a forthcoming paper. Any radical variation in shape influences the numerical value of the degree of true sphericity and affects the size of the surface area, the size of the largest cross-sectional area and the degree of circularity of a great number of cross-sections of a solid. These factors determine to a large extent the settling velocity of that solid. The resistance of wholly submerged bodies, as a theoretical foundation for determining the coefficient of resistance as a function of Reynolds number for solids of different degree of sphericity, is discussed. The influence of the degree of circularity on the resistance is then shown by graphs constructed on the basis of available data. Formulæ for calculating the coefficient of resistance and Reynolds number are introduced and their practical value demonstrated by graphic illustrations. The sedimentological significance and usefulness of the results are discussed.     

An effective splitting-and-recombination micromixer with self-rotated contact surface for wide Reynolds number range applications

It is difficult to mix two liquids on a microfluidic chip because the small dimensions and velocities effectively prevent the turbulence. This paper describes two 2-layer PDMS passive micromixers based on the concept of splitting and recombining the flow that exploits a self-rotated contact surface to increase the concentration gradients to obtain fast and efficient mixing. The designed micromixers were simulated and the mixing performance was assessed. The mixers have shown excellent mixing efficiency over a wide range of Reynolds number. The mixers were reasonably fabricated by multilayer soft lithography, and the experimental measurements were performed to qualify the mixing performance of the realized mixer. The results show that the mixing efficiency for one realized mixer is from 91.8% to 87.7% when the Reynolds number increases from 0.3 to 60, while the corresponding value for another mixer is from 89.4% to 72.9%. It is rather interesting that the main mechanism for the rapid mixing is from diffusion to chaotic advection when the flow rate increases, but the mixing efficiency has not obvious decline. The smart geometry of the mixers with total length of 10.25 mm makes it possible to be integrated with many microfluidic devices for various applications in μ-TAS and Lab-on-a-chip systems.     

具有钝化和激活效应的合作超网络演化机制研究

［目的/意义］合作网络研究是近年来学者关注的一个热点问题,然而传统的网络分析方法只适合刻画两两合作者之间的合作关系,深入分析现实世界中的多人合作关系及其网络发展、演化机制,具有重要的现实意义。［方法/过程］引入超网络理论,构建节点具有钝化和激活状态的演化模型,探讨随机和择优两种驱动机制对合作网络演化过程的影响。仿真发现,择优机制驱动下点超度分布呈幂律分布;随机机制驱动下点超度分布呈指数分布。［结果/结论］选取现实合作网络的数据进行实证分析,实证结果与仿真结果相吻合。说明理论模型对于刻画现实合作网络具有一定的参考价值。     

Study of the rank- and size-frequency functions in the case of power law growth of sources and items and proof of Heaps’ law

Supposing that the number of sources and the number of items in sources grow in time according to power laws, we present explicit formulae for the size- and rank-frequency functions in such systems. Size-frequency functions can decrease or increase while rank-frequency functions only decrease. The latter can be convex, concave, S-shaped (first convex, then concave) or reverse S-shaped (first concave, then convex). We also prove that, in such systems, Heaps’ law on the relation between the number of sources and items is valid.     

Micromixer based on viscoelastic flow instability at low Reynolds number

We exploited the viscoelasticity of biocompatible dilute polymeric solutions, namely, dilute poly(ethylene oxide) solutions, to significantly enhance mixing in microfluidic devices at a very small Reynolds number, i.e., Re≈0.023, but large Peclet and elasticity numbers. With an abrupt contraction microgeometry (8:1 contraction ratio), two different dilute poly(ethylene oxide) solutions were successfully mixed with a short flow length at a relatively fast mixing time of <10 μs. Microparticle image velocimetry was employed in our investigations to characterize the flow fields. The increase in velocity fluctuation with an increase in flow rate and Deborah number indicates the increase in viscoelastic flow instability. Mixing efficiency was characterized by fluorescent concentration measurements. Our results showed that enhanced mixing can be achieved through viscoelastic flow instability under situations where molecular-diffusion and inertia effects are negligible. This approach bypasses the laminar flow limitation, usually associated with a low Reynolds number, which is not conducive to mixing.     

多脉冲位置调制系统中定时误差的误码影响分析

MPPM与PPM相比具有能量信息效率高和带宽低的优点,是激光通信系统中一种有效的通信方式.文章通过理论计算提出了当有定时误差时,(m,2)MPPM具有最小误符号概率的映射列表的设计方法,并且在相同的传输带宽和传输速率下,比较了(m,2)MPPM和PPM的误比特概率.结果表明(m,2)MPPM的性能优于PPM.     

宁波市发明专利的计量分析

以中国专利数据库(知网版)收录的发明专利为数据源,对1986-2011年宁波市9 387件发明专利进行了计量分析,结果显示专利数量增长符合普赖斯指数规律、专利发明人分布符合洛特卡定律、专利权申请人分布符合布拉德福定律的集中与分散规律,并且可用正幂函数进行曲线拟合。     

专利技术范围与专利价值 ——基于生物技术领域专利的分析

[目的/意义]通过计量分析模型探讨专利技术范围是否适合作为专利价值的指标,对专利范围与价值的关系作出新的解释,有助于专利范围指标的合理使用。[方法/过程]通过1985-2014年中国生物技术领域专利数据,构建基于专利IPC分类号的专利范围指标以及技术、法律、经济三个维度的专利价值指标,运用Probit和Poisson回归模型研究专利价值与专利技术范围的关系。[结果/结论]专利技术范围与不同维度专利价值之间的关系存在明显差异,技术范围与专利技术价值之间存在显著正相关,与专利的法律价值显著负相关,但是对专利的经济价值没有影响。因此,在生物技术领域,专利技术范围不是合适的专利价值指标。     

一种基于引文的情感分析方法及其对论文排名指数的影响

[目的/意义]旨在研究引文分析中引入情感分析后对论文排名的影响。[方法/过程]提出一种引文情感分析方法,确定引文文本中的情绪,并使用监督分类器为每个文本句分配一个分数来确定其情感倾向,利用C4.5决策树对引文的极性进行分类;提出一个考虑定量(引用次数)和定性(情感分析)因素的论文评价指数pc指数,并基于该指数对论文进行了排名。[结果/结论]C4.5决策树对引文的极性进行分类,获得了较为准确的结果;pc指数对朴素算法进行改进后获得了对被引论文的影响力新的排名,排名对于较小的语料库影响不大(只有4篇论文排名发生了变化),而对于更大的语料库,预计影响会更大。     

中韩供电企业创新模式与创新能力比较研究

【目的/意义】供电企业作为国民经济的核心部门之一,其科技创新能力在国民科技创新体系中的地位非常重要,创新能力已经成为电力行业持续发展的保证。【方法/过程】通过对中韩两国供电企业创新模式的研究,以创新能力对比研究为基础建立了中韩两国供电企业创新能力指标体系,运用AHP方法和模糊综合评价法对中韩两国供电企业创新能力进行评估,阐述两国供电企业科技创新模式的典型特征和优缺点。【结果/结论】通过横向对比研究提出了我国供电企业科技创新发展的具体建议,为我国供电企业的创新能力水平的提高指明了方向。