双线式螺线管型磨粒传感器设计及其实验研究

为提高螺线管型磨粒传感器的信噪比和检测能力,实现更小金属颗粒的检测,根据并联电感原理设计并制作基于微流道的双线式螺线管型磨粒传感器.对双线式螺线管型磨粒传感器的检测原理进行理论分析,并对相互并联的双线圈等效电感值进行公式推导.使用本文设计制作的双线圈磨粒传感器与传统的单线圈传感器,分别对不同粒径梯度的铁颗粒进行检测与计数,并将检测数据进行对比.实验结果显示,双线圈磨粒传感器可实现5μm铁颗粒的检测;双线式螺线管型磨粒传感器检测信号的信噪比高于单线圈磨粒传感器,最大可达3倍.本文研制的双线式螺线管型磨粒传感器可用于油液中微米级金属颗粒的检测,且具有较高的检测精度.     

微流控芯片上润滑油中微金属颗粒快速分离

润滑油中金属磨粒在线检测是实现船舶机械设备润滑状态监测和故障预判的重要方法之一。为了检测润滑油中不同类型金属磨粒,设计并搭建了微流控芯片上基于离心力作用的金属颗粒分离系统。该系统以微流控芯片为平台,设计了圆弧形流道结构,利用ANSYS CFX软件对微颗粒运动进行仿真模拟。实验操纵金属颗粒在离心力作用下实现分离,并进入不同种类金属颗粒通道。仿真和实验研究结果表明,所设计的金属颗粒分离系统可实现润滑油液中直径为15μm的铜、铝颗粒的有效分离。     

颗粒速度对电磁式磨粒监测结果一致性的影响机制

随着机械系统复杂程度及运行可靠性要求的逐渐提高，电磁式磨粒在线监测传感器被广泛研究并逐步应用于机械设备磨损状态监测领域.针对润滑油液中金属磨损颗粒运动速度的随机性导致电磁式磨损颗粒检测传感器检测结果一致性差的问题，建立了交变磁场中金属球体磨损颗粒磁特性模型，研究磨损颗粒局部磁感应强度分布规律以及磁能扰动计算方法；同时提出并实验测得了非铁磁性磨损颗粒的磁能损耗系数，进而对传感器输出的颗粒信号进行补偿.实验表明该方法可以消除磨损颗粒运动速度对传感器输出信号幅值的影响，极大地提高传感器对非铁磁性磨损颗粒检测结果的一致性.     

气-液-固三相磨粒流旋流流场分析及加工实验研究

针对现有流体加工方法中加工效率低、易出现工件表面各区域加工纹理不均匀的问题,提出一种气-液-固三相磨粒流抛光加工新方法.基于Realizable k-ε湍流模型和Mixture模型,建立气-液-固三相磨粒流抛光加工数值模拟模型.数值模拟结果揭示了气-液-固三相磨粒流形成的高速湍流涡旋流场动力学特性,同时也发现了磨粒流流场中磨粒和微气泡的运动及分布规律,得到较优适用于气-液-固三相磨粒流抛光加工磨粒流入射角度设计参数,并设计出实验抛光工具.经过1h的实验加工后,与无微气泡条件的液固两相流抛光加工对比,气-液-固三相磨粒流抛光加工的工件表面相同区域的粗糙度值更低,纹理也更为均匀.上述研究结果表明:气-液-固三相磨粒流的流场特性提高了磨粒和微气泡运动的无序性及微气泡溃灭的概率,且磨粒流中的微气泡溃灭所释放的能量提高了磨粒的抛光加工效率.     

高梯度静磁场的多通道磨粒检测传感技术研究

针对机械设备磨损在线检测系统存在的大流量和高灵敏度难以同时满足的问题，提出了基于对向布置环形磁铁的多通道磨粒在线检测传感器结构. 通过建立传感器磁特性及铁磁性磨粒磁化的数学模型，推导得到了磨粒通过传感器时磁场扰动的解析解；进而采用仿真与实验的方法验证了传感器结构参数对传感器性能的影响规律. 研究表明，铁磁性球体磨粒通过传感器时，其内部磁感应强度约为背景磁感应强度的3倍，且传感器感应线圈布置于磁铁外边缘比布置于磁铁内边缘时的检测灵敏度高约10.1%；同时，随着磁铁外径及两磁铁轴向间距的增加，传感器输出感应电压呈现先增加后下降的趋势.采用优化后结构参数的传感器可实现直径80 μm铁磁性磨粒的有效检测.     

关于磨粒在磁场探测器中沉降运动的研究

将含有铁磁性磨粒的油流看作具有铁磁流体性质的多相流,通过直接测量及数据拟合得到了电磁场场强及梯度分布的解析式;研究了非均匀磁场中特定条件下的粘度表达式、铁磁性磨粒沉降运动规律及磨粒直径Ｄ、颗粒容积率及含气泡的多相流对磨粒沉积的影响．研究结果认为：铁磁性磨粒在整个沉降过程中速度与加速度均在变化,达不到恒定的沉降速度;磨粒直径、颗粒容积率对靡磨粒沉积位置有影响,而气泡对其影响不大,所得结论对在线铁谱技术研究具有重要的指导作用     

电感式磨粒在线监测传感器灵敏度提高方法

电感式磨损颗粒在线监测传感器的研究所面临的主要瓶颈是传感器灵敏度与孔径之间存在矛盾,灵敏度较高的传感器一般采用微流道结构(孔径1mm),最大允许流量小;而大孔径的传感器其灵敏度较低.为满足重型机械磨损状态在线监测的需求,研究了大孔径(7mm)的电感式磨粒监测传感器灵敏度提高方法.提出使传感器工作于全谐振状态,其中激励线圈工作于并联谐振状态,感应线圈工作于串联谐振状态,共同增强颗粒引起的传感器输出感应电动势.检测机理上建立了交变磁场中金属颗粒对磁场的扰动模型,考虑了颗粒在交变磁场中的涡流效应,提高了模型的实用性.实验表明谐振原理极大地提高了传感器的灵敏度,实现了直径75μm铁磁性颗粒和220μm非铁磁性颗粒的有效检测,初步满足了重型机械设备初期异常磨损阶段的在线监测需求.     

低微水的体积分数对SF_6局部放电及分解特性的影响

为了研究交流电压、低体积分数(1 350×10-6)条件下水分对SF6气体局部放电及分解特性的影响,搭建了SF6绝缘电力设备实验及检测平台,详细描述了金属突出物缺陷下局部放电量及SOF2、SO2F2、SO2、CO2等4种气体分解产物随微水的体积分数的变化规律。结果表明,平均局部放电量和总体放电量都随微水的体积分数呈现先下降后上升的趋势;微水的体积分数的增加对几种产物均有促进作用,且对3种含硫产物的促进作用强于对CO2的促进作用。气体产物体积分数比值φ(SOF2+SO2)/φ(SO2F2)随微水的体积分数的变化表现出较好的稳定性,最终稳定在3~4之间;φ(SOF2+SO2+SO2F2)/φ(CO2)则随着φ(H2O)的增加呈现总体增长的趋势,其低微水的体积分数下的值在2.5~3之间。因此,SF6气体分解检测法应用过程中需要充分考虑微水的体积分数的影响。     

裂缝深度对磁记忆信号影响的研究

磁记忆检测方法是利用工件中地球磁场变化信息研究铁磁性材料的应力集中、裂纹萌生等问题。以预置裂纹标准块为研究对象,研究裂纹深度与磁记忆信号的关系。研究发现,裂缝深度与漏磁场梯度变化呈非线性关系,与磁场强度最大值、过零点无映射关系,且表面漏磁场的分布区域愈宽,漏磁场的变化幅度越小。研究结果对磁记忆的磁性金属的裂纹识别具有重要指导意义。     

块体金属玻璃微磨削加工的温度场仿真

建立单颗磨粒微磨削的正交切削模型和玻璃金属的本构关系方程,采用有限元工艺仿真系统对块体金属玻璃进行微磨削加工的温度场仿真,从而得到块体金属玻璃在微磨削过程中的温度以及温度变化趋势,进而观察其磨削温度是否达到块体金属玻璃的玻璃转变温度.因此,对玻璃金属磨削加工过程的温度仿真可以有效预测非晶表面是否有晶化现象的发生.改变微磨削加工参数,对块体金属玻璃的各个磨削区的温度变化趋势进行观察.通过仿真实验发现,块体金属玻璃的最高磨削温度发生在磨粒前刀面与磨屑接触的区域,即第二变形区.     

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.     

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.     

An Analysis of Catherine＇s Character——Wuthering Heights

Wuthering Heights, Emily Bronte＇s only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.     

Lower Paleozoic oil relationships within Williston Basin, Canada

The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.     

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.     

Design and analysis of generic LBS application developing platform

Location based services is promising due to its novel working style and contents.A software platform is proposed to provide application programs of typical location based services and support new applications developing efficiently. The analysis shows that this scheme is easy implemented, low cost and adapt to all kinds of mobile nework system.     

Achieving Unusual States of Matter Under High Pressure

正The periodicity of the elements and the non-reactivity of the inner-shell electrons are two related principles of chemistry,rooted in the atomic shell structure.Within compounds,Group I elements,for example,invariably assume the+1 oxidation state,and their chemical properties differ completely from those of the p-block elements.These general rules govern our understanding of chemical structures and reactions.Using first principles calcula-     

Exchange-Correlation and Electronic Excitation Energies from Pairing Matrix Fluctuations

We have developed an adiabatic connection to formulate the ground-state exchange-correlation energy in terms of pairing matrix linear fluctuations.This formulation of the exchange-correlation energy opens a new channel for density functional approximations based on the many-body perturbation theory.We illustrate the potential of such approaches with an approximation based on the particle-particle Random Phase Approximation(pp-RPA).This re-     

Density Functional Theory for the Response of Periodic Systems to Electric Fields Based on the Vector Potential Approach

正The electronic and nuclear(structural/vibrational)response of 1D-3D nanoscale systems to electric fields gives rise to a host of optical,mechanical,spectral,etc.properties that are of high theoretical and applied interest.Due to the computational difficulty of treating such large systems it is convenient to model them as infinite and periodic(at least,in first approximation).The fundamental theoretical/computational problem in doing so is that