电压稳定剂改善聚乙烯共混材料绝缘性能的研究

为了开发新一代可回收电缆材料,提升其绝缘性能,选取间氨基苯硼酸、2-甲氧基-5-吡啶硼酸和间氨基苯甲酸3种新型电压稳定剂添加入聚乙烯共混物中,分析其对聚乙烯共混物绝缘性能的改善作用及机理。采用溶液法将质量分数为1%的电压稳定剂添加入含质量分数为10%高密度聚乙烯(HDPE)的低密度聚乙烯(LDPE)共混材料,通过热压法制备试样,利用红外光谱、差式扫描量热法、X射线衍射、电树枝起始实验、直流电导率和空间电荷测量对材料进行物理化学分析和电气性能测试。研究结果表明,聚乙烯共混提升了热稳定性和结晶度,添加电压稳定剂后进一步提升了共混物的结晶度,对共混物的熔融特性无明显影响。添加了电压稳定剂的共混物的电树枝起始电压均明显提高,间氨基苯甲酸共混物的电树枝起始电压比LDPE/HDPE共混物提高了47%。电压稳定剂对共混物的直流电导率作用明显,间氨基苯甲酸能够明显降低共混物的直流电导率。3种电压稳定剂对共混物的空间电荷积累具有明显的抑制作用,且添加了间氨基苯硼酸的共混物具有最少的空间电荷积累。陷阱能级和视在迁移率计算发现,添加了电压稳定剂的共混物中浅陷阱密度增加,视在电荷迁移率增大,有利于抑制材料中空间电荷的积累。实验结果可为新一代环保电缆的开发提供一定参考。     

用陷阱参数作为聚合物电老化特性参数的试验研究

本文以高分子聚丙烯薄膜材料为试样,在真空与均匀电场中进行加速电老化试验。试验结果表明,试样的老化场强与老化时间呈指数关系。在电老化过程中,用红外光谱分析了试样的内在化学结构变化,用电子顺磁共振测量了老化生成的自由基,用光电导谱和表面电位的测量技术测量了陷阱深度与陷阱密度的变化。试样在电老化过程中,短分子链随时间而增加,陷阱的深度与密度也随时间而增长,都与电老化寿命的经验公式有类似的形式。通过讨论电老化的化学过程,提出陷阱参数可以作为表征材料电老化特性的新参数。本文的结论将为建立新的电老化理论提供了试验依据,并为非损伤性电老化试验创造了前景。     

液态聚硫橡胶对环氧树脂介电性能的影响

为了研究环氧增韧剂液态聚硫橡胶(PSR)对环氧树脂介电性能的影响,采用直接共混法制备了PSR/环氧树脂复合材料试样(PSR的质量分数分别为0%、5%、10%、15%和20%),通过扫描电子显微镜和差示扫描量热法对试样的微观形貌和玻璃化转变温度进行分析,测试了试样的直流击穿场强、频域介电谱和表面电位衰减特性。测试结果表明:PSR的添加会导致环氧树脂玻璃化转变温度降低;添加PSR能够有效提升环氧树脂的直流击穿场强;环氧树脂介电常数和介质损耗随着PSR质量分数的增大先增大后减小;PSR会使环氧树脂的表面电位衰减速度减慢。通过等温表面电位衰减模型提取陷阱参数发现,添加PSR后,深、浅陷阱中心的深度增大,深陷阱电荷的密度随着PSR浓度的增大先减小后增大,除了PSR质量分数为20%外,其余含量PSR的添加均会导致浅陷阱电荷密度减小。基于电荷输运过程以及空间电荷击穿理论,认为陷阱深度的增大使陷阱捕获效应增强,导致碰撞电离和空间电荷的累积受到抑制,从而提高了直流击穿场强。     

新型压电共聚物P(VDF-HFP)薄膜驻极体

通过正负电晕极化、热刺激放电电流谱(TSD)、激光振动测量与分析等方法,研究了用流延法制备的经过机械热拉伸前后的两种不同HFP含量(HFP含量分别为4.7%和5.9%)新型共聚物薄膜的驻极体特性.实验结果说明,拉伸前后的这类共聚物薄膜均是极性材料,即充电极化后的材料内部同时存在取向偶极子和俘获空间电荷.正电晕极化较负电晕极化更能提高偶极电荷和空间电荷的热稳定性.对样品实施的机械热拉伸工艺能显著增强材料的极化强度,即不仅增加了取向偶极子的浓度,而且空间电荷的储存密度也大大上升;同时在一定程度上改善了空间电荷的热稳定性.但HFP含量的上升则显著降低了偶极子取向强度和空间电荷的俘获能力.HFP含量为4.7%的共聚物薄膜具有高达133pm/V的逆压电d33系数.     

液氮环境下电老化对聚丙烯层压纸交流击穿及陷阱分布特性的影响

为了研究高温超导电缆绝缘材料聚丙烯层压纸(PPLP)在实际服役过程中的老化规律及机理,对PPLP绝缘材料进行了不同程度的电老化,通过交流击穿及等温表面电位衰减研究了电老化对PPLP绝缘材料击穿特性及陷阱分布特性的影响,并结合红外光谱、显微形貌观测和热重实验分析其老化机理。实验结果表明:随着电老化程度的增大,PPLP绝缘材料的交流击穿场强由113.3kV/mm降低至92.3kV/mm,浅陷阱密度逐渐增大,深陷阱密度逐渐减小;PPLP外层绝缘纸结构趋于松散,部分纤维素断裂,表面出现大量孔隙,绝缘纸内部氢键及糖苷键对应的红外吸收峰强度降低;同时,绝缘纸的最快热失重温度降低,而中层聚丙烯的热失重过程未发生明显变化,说明在老化过程中PPLP绝缘性能下降的主要原因在于外层绝缘纸的劣化。分析认为:纤维素分子主链上的糖苷键以及分子间的氢键在高能电子的撞击下发生断裂,分子间作用力减弱,结构致密性降低;绝缘纸内部自由体积增大,纤维素分子链段对电荷的束缚能力减弱,电荷更容易在分子链间进行迁移,进而导致PPLP绝缘深陷阱密度和交流击穿场强降低。     

低温下聚合物电介质中的空间电荷及其对介电性能的影响

聚合物电介质材料在低温(接近或低于液氮沸点)下比室温下能俘获更多由电极注入的带电粒子并形成空间电菏,将影响聚合物电介质在低温下的介电性能.本文用电声脉冲法和热刺激电流法(TSC)测量了空间电荷的分布及陷阱能级,表明该现象与聚合物电介质中存在的浅能级局部态有关.本文的研究为选用低温电气绝缘聚合物材料提供了新的依椐.     

对 a-SiC∶H膜平面电极结构样品的空间电荷限制电流的测量

对平面电极结构样品用测量空间电荷限制电流(SCLC)的方法测 GD—a—SiC∶H 膜的隙态密度 N(E),通过测量临界电压与电极间距的关系 Vc～d 从而确认 SCLC 的存在;按隙态的指数分布由超线性 I～V 曲线确定出描述隙态的特征温度 Tt 和陷阱参量 Nt 从而测得 N(E),我们得到 N(E_F)约为2×10~(15)/Cm~3·ev.     

电老化与加速水树老化对交联聚乙烯绝缘理化特性的影响

为了研究电老化(ETA)和加速水树老化(AWTT)对交联聚乙烯(XLPE)绝缘理化特性的影响,分别对ETA和AWTT的实际电缆试样进行红外光谱(FTIR)、X射线衍射(XRD)和热质量分析(TG)测试,分析其理化特性随着老化的变化规律。建立了AWTT的微观模型,从微观形态变化、陷阱的形成角度对老化机理进行了深入分析。结果发现:ETA和AWTT试样绝缘内R1R2CCH2、—OH键均出现上升趋势,AWTT试样羟基增长速率大于ETA试样,而两种老化过程中双键的增加速率相当;ETA试样电缆绝缘结晶度先上升后下降,AWTT试样电缆绝缘结晶度呈下降趋势;ETA与AWTT都使得绝缘热稳定性下降,ETA试样的微分热质量(DTG)曲线未出现分峰现象,AWTT试样DTG曲线在老化后分裂出多个峰,老化时间越长分裂的峰越多。对试验结果进行分析,在老化过程中,理化特性的变化规律可以由微观模型结合陷阱的变化进行合理解释,老化过程中产生的陷阱对绝缘性能产生重要影响。     

电子陷阱对卤化银微晶感光过程的影响

根据成核-生长模型详细阐述了卤化银微晶中电子陷阱与空穴陷阱的概念以及电子陷阱在感光过程中的作用,着重于介绍如何优化电子陷阱密度和深度来降低复合以及成核点数目,从而达到提高潜影形成效率的目的.     

用空间电荷限制电流方法研究非晶硅中的隙态密度

1 引言非晶硅能带中的隙态密度分布N(E)对材料的光电性能有着重大影响,因而对它的准确无误的测试是相当重要的。目前,人们对非晶硅隙态密度的分布形貌仍存在着不同程度的分歧。我们用空间电荷限制电流方法较系统并且细致地测试了非晶硅的隙态密度分布。除此还     

Markedness and its Interpretation in Language Use

Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.     

Characterization of Ordovician carbonate reservoirs, southeastern Saskatchewan, Canada

The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3～4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰～ -7.8‰, PDB) and matrix dolomites (-6.6‰～ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084～0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078～0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.     

Features of Women's language

Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women＇s language from these perspectives： pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women＇s language, more attention should be paid to language use in social context. What＇s more, the linguistic phenomena in a speaking community can be understood more thoroughly.     

A computer generator for randomly layered structures

AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…     

低渗透非均质砂岩油藏启动压力梯度研究

理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。     

On Tragic Consciousness In The Works By Ernest Hemingway

As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.     

海南岛地体及其毗邻陆缘晚中生代—新生代古地磁研究和构造演化

本文叙述了对海南岛及其毗邻大陆边缘白垩纪到第四纪地层岩石进行古地磁研究的全部工作过程。通过分析岩石中剩余磁矢量的磁偏角及磁倾角的变化,提出海南岛白垩纪以来经历的构造演化模式如下:早期伴随顺时针旋转而向南迁移,后期伴随逆时针转动并向北运移。联系该地区及邻区的地质、地球物理资料,对海南岛上述的构造地体运动提出以下认识:北部湾内早期有一拉张作用,主要是该作用使湾内地壳显著伸长减薄,形成北部湾盆地。从而导致了海南岛的早期构造运动,而海南岛后期的构造运动则主要是受南海海底扩张的影响。海南地体运动规律的阐明对于了解北部湾油气盆地的形成演化有重要的理论和实际意义。     

An Index mechanism for multi-scale view in spatial databases

There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.     

《Chinese Science Bulletin》SUBJECT INDEX TO VOLUME 59(2014)

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Achieving Unusual States of Matter Under High Pressure

The elongation method,originally proposed by Imamura was further developed for many years in our group.As a method towards O(N)with high efficiency and high accuracy for any dimensional systems.This treatment designed for one-dimensional(ID)polymers is now available for three-dimensional(3D)systems,but geometry optimization is now possible only for 1D-systems.As an approach toward post-Hartree-Fock,it was also extended to