Phase transition of DNA compaction in confined space: Effects of macromolecular crowding are dominant

With a view of detecting the effects of macromolecular crowding on the phase transition of DNA compaction confined in spherical space,Monte Carlo simulations of DNA compaction in free space,in confined spherical space without crowders and in confined spherical space with crowders were performed separately.The simulation results indicate that macromolecular crowding effects on DNA compaction are dominant over the roles of multivalent counterions.In addition,effects of temperature on the phase transition of DNA compaction have been identified in confined spherical space with different radii.In confined spherical space without crowders,the temperature corresponding to phase transition depends on the radius of the confined spherical space linearly.In contrast,with the addition of crowders to the confined spherical space,effects of temperature on the phase transition of DNA compaction become insignificant,whereas the phase transition at different temperatures strongly depends on the size of crowder,and the critical volume fraction of crowders pertains to the diameter of crowder linearly.

Implementation of Phase Generated Carrier Technique for FBG Laser Sensor Multiplexed System Based on Compact RIO

This paper presents the fundamental technique of phase generated carrier （PGC） and its realization on compact reconfigurable input and output （RIO） which adopts real-time and field programmable grate array （FPGA） techniques. Improvement of the PGC technique is also introduced by using peak-to-peak value detection method to reduce the influence of variation of the light intensity. A four-element fibre Bragg gratings （FBG） laser sensor system is conducted in the experiment and the demodulated results demonstrate correlation coefficient as high as 0.995 with the reference signal and the dynamic range to be 120dB@63Hz.

A review of compact modeling for phase change memory

Phase change memory(PCM)attracts wide attention for the memory-centric computing and neuromorphic comput-ing.For circuit and system designs,PCM compact models are mandatory and their status are reviewed in this work.Macro mod-els and physics-based models have been proposed in different stages of the PCM technology developments.Compact model-ing of PCM is indeed more complex than the transistor modeling due to their multi-physics nature including electrical,thermal and phase transition dynamics as well as their interactions.Realizations of the PCM operations including threshold switching,set and reset programming in these models are diverse,which also differs from the perspective of circuit simulations.For the purpose of efficient and reliable designs of the PCM technology,open issues and challenges of the compact modeling are also discussed.

Compact passing algorithm for signalized intersection management based on vehicular network

To improve the traffic efficiency at signalized intersections, a compact passing algorithm is proposed based on a vehicular network. Its basic principle is that several waiting vehicles after the stop line of the considered intersection should simultaneously start in green periods. Thus, more vehicles can pass the intersection in a green period. Then, the having passed vehicles should follow the planned trajectories to enlarge their longitudinal clearances. Phase timing is not considered in the compact passing algorithm, and therefore, the proposed compact passing algorithm can be combined with other algorithms on phase timing to further improve their performances. Several simulations were designed and performed to verify the performance of the proposed algorithm. The simulation results show that the proposed algorithm can increase the number of completed vehicles and decrease the travel time in the signalized intersections managed by fixed-time and vehicle actuated algorithms, which indicates that the proposed algorithm is effective for improving the traffic efficiency at common signalized intersections.

The Formula of Dependence of Mechanical Characteristics of Materials on Crystalline Phase Composition in the Matrix

Objective: For materials science and generally, for long-term operation of work-pieces in industry the significant role is attributed to dependence of macro-mechanical properties of consolidated body on crystalline phase composition, its dimensions, form, distribution in matrix and the form factor. While working in responsible fields of technology of ceramics and ceramic composites the above referred properties are attributed extremely great role with the view of durability and endurance at the terms of heavy mechanical loads. For description of the resistance of any concrete type work-piece, the crystalline phase plays the greatest role in mechanical strength or deformation of any material. It plays the important role in correlative explanation of materials mechanics and matrix properties. In our case, in the process of destruction of ceramic materials and composites, which will give us exhaustive response to the role of macro- and micro-mechanical properties of materials, the role of a macro- and micro-structural component, that is, of crystalline phase in the process of transition of stable state of materials into meta-stable state is extremely big. Our study aims to develop a formula of dependence of macro-mechanical properties of ceramic and ceramic composites on crystalline phase, the most powerful component of their structure, which will enable theorists and practitioners to select and develop technologies and technological processes correctly. Method: On the basis of the study of micro- and macro-mechanical properties of ceramics and ceramic composites and the morphology of crystalline phase and the analysis of the study we determined and created parameters of the formula. Results: The formula covers macro-mechanical properties, that is when the work-piece is thoroughly destructed: mechanic at bending at three and four-point load, mechanic at contraction;among morphological characteristics: composition of crystalline phase and their spreading in matrix, their sizes, form factor;correlative dependence of the above listed properties. Absolutely new definition of a factor of spreading of crystalline phase in matrix is offered. Conclusion: The created formula is of consolidated nature and it can be used in technology of any ceramic material and ceramic composites. The formula will help practitioners to plan correctly and fulfill accurately all positions of technology of production of work-pieces, to carry out the most responsible thermal treatment process of technology of manufacture of work-pieces;to determine correlation between mechanical and matrix properties of materials.

Development of Tailored Structure and Tensile Properties of Thermomechanical Treated Micro Alloyed Low Carbon Dual Phase Steel

Direct hot rolled dual phase steel production represents a challenging route, compared with cold rolled and intercritical annealing process, due to complex and sophisticated control of the hot strip mill processing parameters. Instead, high technology compact slab production plant offers economic advantages, adequate control and prompt use of the advanced thermomechanical controlled rolling. The current work aims to obtain different structures and tensile properties by physical simulation of direct hot rolled niobium micro alloyed dual phase low carbon steel by varying the metallurgical temperatures of hot strip mill plant. This starts with adaptation of the chemical analysis of a low carbon content to fall far from the undesired peritectic region to avoid slab cracking during casting. Thermodynamic and kinetics calculations by Thermo-Calc 2020 and JMat pro software are used to define the transformation’s temperatures Ae1 and Ae3 as well as processing temperatures;namely of reheating, finishing rolling, step cooling and coiling temperatures. The results show that the increase of finishing rolling temperature from 780°C to 840°C or decreasing either of step cooling duration at ferrite bay from 7 to 4 seconds, enhances yield and tensile strengths, all due to more martensite volume fraction formation. The yield and tensile strengths also increase with decreasing coiling temperature from 330°C to 180°C, which is explained due to the increase of dislocation densities resulted from the sudden shape change during martensite formation at the lower coiling temperature in additional to the self-tempering of martensite formed at higher coiling temperatures which soften the dual phase steel.

Microstructure of explosively compacted Nd-Fe-B magnet by TEM

The microstructure of an explosively compacted Nd-Fe-B permanent magnet（Nd-Fe-B） was investigated by means of TEM and XRD. It is shown that there are three kinds of phases: Nd2Fe14B matrix phase, O-rich phases and Nd-rich phase with different structures and compositions in the magnet. The hard magnetic phase Nd2Fe14B is tetragonal, which lattice parameters are determined to be a=0.88 nm and c=1.22 nm. The O-rich phase locates at the grain boundaries and the triple junctions has fcc structure whose lattice parameter is a=0.559 nm. A dislocation is observed in this phase. It is also found that a large number of the block-shaped Nd-rich phases with hcp structure are embedded in the Nd2Fe14B matrix or at grain boundary. Their lattice parameters are determined to be a=0.395 nm and c=0.628 nm.

紧凑型混合励磁三相饱和铁芯型故障限流器

加装饱和铁芯型故障限流器是限制高压系统短路电流的有效方法,但其需要与外加的限流空心电抗器配合,导致整个限流系统占地面积和体积很大。因此,基于非正交解耦原理提出了一种紧凑型混合励磁三相饱和铁芯型故障限流器(compact hybrid-biased three-phase saturated core fault current limiter,CTFCL),其具有占地面积和体积小的优点。首先,提出了含非正交解耦绕组的CTFCL拓扑。其次,建立了CTFCL的等效电磁路模型,分析了其工作原理。然后,给出CTFCL的参数设计准则,搭建了220 kV的有限元模型,仿真验证了CTFCL的限流效果和电磁特性。最后,设计并研制出小容量样机,开展了实验研究。仿真和实验结果均证明了该文所提CTFCL的有效性,CTFCL对各种短路均有良好的限制效果,且对比得到CTFCL限流系统占地面积和体积较传统三相SCFCL限流系统分别减少了44%和26%,适合实际高压系统的安装与应用。

高压作用下水泥基粉末材料的接触硬化研究综述

在高压作用下,一些具有无定型相的水泥基粉末材料会发生接触硬化现象,粉末颗粒在压力作用下发生缩聚运动,并在粉末颗粒间形成结构键,进而快速形成具有一定强度及耐水性的人造石材。本文综述了压力作用下水泥基粉末材料接触硬化的成键机理以及粉末水分含量、干燥条件、钙硅比、压制过程对其接触硬化性能影响的研究进展。相关研究结果表明,压力作用下粉末颗粒间会形成氢键、范德华力、固体桥键等结构键;粉末水分含量是影响接触硬化性能的重要因素,在压力作用下,水分可以改变粉末颗粒的表面性质并影响颗粒之间的结合,进而改变压制成品的力学性能;钙硅比对接触硬化性能的影响显著,不同粉末材料在压制时的最佳钙硅比亦是不同;摩擦力的存在降低了压制效率,造成压制成品密度、强度分布不均匀,润滑剂的加入可以有效降低摩擦力的影响;此外,降低压制模具高径比并使用双面压制可有效提升压制成品的质量。

相间间隔棒对紧凑型输电线路脱冰跳跃响应影响研究

紧凑型输电线路穿过覆冰区容易因导线脱冰跳跃而引起放电跳闸及金具破坏事故。揭示紧凑型输电线路脱冰后的动力响应规律,对线路工程的抗冰设计及加固改造具有重要的指导意义。以某500kV紧凑型线路脱冰跳跃跳闸故障为例,通过数值模拟仿真,考察了在实际覆冰厚度下,不同相导线脱冰时,线路的相间间隙以及相间间隔棒受力变化;继而针对最不利安全间隙工况,通过参数分析,提出该线路相间间隔棒布置的优化策略。研究结果表明:1)尽管设置相间间隔棒可以有效抑制脱冰相的竖向跳跃高度,增大导线与地线之间间隙,但对于倒三角形分布的紧凑型线路而言,布置相间间隔棒会减少脱冰后相间间隙。2)下相导线脱冰较上相导线脱冰更容易导致相间间隙不足;且由于上-下相相间间隔棒对下相导线跃起时的侧推作用,容易造成相间间隔棒附近处非连接相间间隔棒一侧的上下相相间间隙不足。3)紧凑型线路相间间隔棒数量和布置位置对脱冰后相间间隙均有影响,其中将相间间隔棒布置远离档距中央可有效增加相间间隙。4)上相脱冰和下相脱冰中与脱冰相有连接的上下相之间的相间间隔棒张力最大;下相脱冰相间间隔棒张力比上相脱冰相间间隔棒张力大,易造成金具损坏,设计中需重点关注。5)由于相邻档对脱冰档的张力作用会增加脱冰跳跃高度进而减少相间间隙,采用耐张串替代V型串有效减少相邻档的负面影响。

紧凑空间下大规模数字相控阵混合ADC接收机性能分析

针对紧凑空间互耦效应影响下的大规模数字相控阵混合ADC接收机性能评估问题,提出一种混合ADC接收机性能分析方法。首先,通过联合考虑三维信道模型、互耦效应模型和ADC量化噪声模型,对互耦效应影响下的传播信道进行建模;然后,采用线性最大比合并接收机,基于随机矩阵理论,推导给定天线阵列拓扑结构下系统可达速率的闭式表达式;最后,分别对均匀线性阵列、均匀平面阵列在不同混合ADC配置方案下的可达速率进行理论计算和数值仿真。计算与仿真结果均表明优化混合ADC配置方案可以有效提升系统可达速率,该结论可以为紧凑空间下高可达速率的混合ADC接收机设计提供理论支撑。

多通道平行流扁管-紧凑式翅片相变蓄热器蓄/放热性能

工业余热浪费严重、利用率较低且实际应用过程中受到时间和空间的限制,需要高效蓄热技术和装置来解决此类问题。提出一种将多通道平行流扁管与紧凑式翅片相结合的新型相变蓄热器,以水为载热流体,月桂酸为相变材料。实验研究了载热流体注入方式、流量、入口温度对蓄热器蓄/放热性能的影响,并分析小温差下蓄热器的传热特性。结果显示,该蓄热器相变材料填充率为82.5%,紧凑式翅片的采用极大强化了相变材料侧换热过程,蓄/放热性能优良。当载热流体入口温度分别为45℃和41℃时,相变材料约在270 min和75 min完成相变,最小蓄/放热温差可达2℃,最小温差时的平均蓄热比功率为25.18 W/kg,平均取热比功率为20.23 W/kg。

镁合金微弧氧化陶瓷层生长过程及微观结构的研究

利用扫描电镜 (SEM)、X射线衍射 (XRD)等分析手段 ,研究了MB8镁合金微弧氧化陶瓷膜层的生长规律 ,分析了微弧氧化条件下氧化镁膜层致密性和相结构与处理时间的关系。结果表明 ,在微弧氧化初期膜层致密 ,几乎观察不到疏松层 ;随着处理时间的延长及膜层的增厚 ,其外侧开始出现疏松层 ,最终可达到膜层总厚度的 90 %左右。膜层相结构主要由MgO、MgSiO3、MgAl2 O4和无定形相组成。随着膜层厚度的增加 ,膜层中MgO、MgAl2 O4的含量不断地增加 ,MgSiO3 的含量基本不变 。

紧凑而可靠的新型126kV三相共筒型GIS

笔者介绍了一种紧凑而可靠的新型126 kV三相共筒型GIS,同时对产品的成本进行了分析。分析结果表明,新设计在基础材料成本、运输、运行、维护成本上均有一定的优势。

750kV紧凑型线路相间间隔棒力学分析与计算

750kV同塔双回紧凑型线路在国内外尚无先例,因此在杆塔型式选择,绝缘子串及相间合成间隔棒设计上需要进行很多开创性的工作。为了给我国第1条750kV同塔双回紧凑型输电线路的相间合成间隔棒提供设计依据,对750kV同塔双回紧凑型输电线路相间间隔棒力学特性进行了深入研究。首先引用大挠度理论介绍了750kV同塔双回紧凑型线路的相间合成间隔棒的稳定后屈曲特性,然后又采用一种相间间隔棒的精确受力模型通过计算机仿真计算了相间合成间隔棒所承受的压力与轴向压缩量的关系,并且通过它的大屈曲试验验证了这种精确受力模型的正确性,通过比较34和40mm两种不同芯棒直径的相间间隔棒的试验与仿真数据,最后给出了750kV同塔双回紧凑型线路相间合成间隔棒的芯棒直径的推荐值为40mm。

220kV紧凑型输电线路相间合成绝缘间隔棒的研究

介绍了我国第一条220kV安-廊线紧凑型线路相间合成绝缘间隔棒研究成果及设计经验．特别通过对相间合成绝缘间隔棒后屈曲性态、绝缘水平的综合研究和分析，提出了相间合成绝缘间隔棒新的设计概念，并在国内首次研制成220kV紧凑型线路用的相间合成绝缘间隔棒．研制的间隔棒已全部通过按技术条件要求的机电综合试验，为紧凑型线路的工程实施解决了一个技术难题．也为研究更高电压500kV紧凑型线路用的相间合成绝缘间隔棒创造了条件．

一种蜜胺树脂为壁材的相变储热微胶囊致密性研究

采用原位聚合法用蜜胺树脂包覆了一种相变点为24℃,相变热为225 5J/g的有机复合相变材料,并对所制备的相变储热微胶囊的致密性进行了研究。利用扫描电子显微镜对微胶囊的表面形态进行了观察;用722型分光光度计对不同工艺条件下所得微胶囊在密度为0.79g/mL乙醇中的渗透性进行了研究;采用压力法观察微胶囊在受压后的表面形貌,对其强度进行了评价。结果表明:相变储热微胶囊呈均匀的球形,表面光滑且致密,平均粒径110μm;由于蜜胺树脂有大的交联密度,微胶囊在乙醇中渗透缓慢,证明芯材包覆效果好,同时发现双层壁材微胶囊的致密性优于单层壁材的微胶囊;平均粒径为10μm的优于平均粒径为1μm的;随着壁材用量的增大,渗透性减弱,但为了保证相变储热微胶囊的储热效果,芯材与壁材质量比以3为好。所制备的微胶囊可以承受1 96×105Pa的压力而不破损。

振荡压实度计的试验与研究

通过试验验证了振荡轮的轮心水平运动和轮缘切线运动之间的相位差与土壤压实度之间具有稳定的线性关系，从而确定了相位差振荡压实度计的测量原理。

新型718合金的元素强化作用及组织稳定性研究

通过对718合金中沉淀强化元素Al,Ti以及固溶强化元素W含量的调整,研究了δ相形成规律及合金中γ′′/γ′复合析出组织的形成条件,同时分析了合金的微观组织与力学性能之间的关系。结果表明,维持理想的(Al+Ti+Nb)含量(at%)及(Al+Ti)/Nb原子分数比可以显著减少针状δ相的析出,得到稳定的γ′′/γ′复合析出组织并提高合金的拉伸强度、持久及硬度等多项力学性能。而在718合金基础上,采用W强化的合金与原型718合金相比也显现出了更为优异的力学性能。

Al含量对GH4169镍基合金组织及其稳定性的影响

GH4169合金中当Al含量处于合金标准范围内(0.45%)时,其晶内强化相γ″和γ′分开析出,晶界主要析出相为δ相;当Al含量为1.24%以上时,合金晶内析出γ″/γ′"包覆组织",晶界δ相显著减少,而析出了大量的Laves相和少量的M_7C_3相及σ相.680℃,1000h长期时效后,高Al合金中"包覆组织"长大缓慢,但晶界相数量显著增加,尺寸明显长大,而且析出了α-Cr相.随Al含量增加,这种趋势更加明显.Al含量增加显著地降低合金的室温冲击韧性,680℃长期时效后,冲击值更低.