25Hz交流计数电码机车信号数字滤波器的研究

介绍25Hz 交流计数电码信号数字滤波器的研究设计.机车信号设备接收钢轨中的25Hz 交流计数电码信号时受到了严重的干扰信号的干扰,其中最严重的是50Hz 不平衡钢轨牵引电流的干扰.作者设计了 FIR型的数字滤波器,它应用在新型的全数字化的机车信号中.通过实验验证了所设计的 FIR 型25Hz 交流计数电码信号数字滤波器的性能可以满足机车信号的特殊要求.     

ZL201合金低频电磁铸造与二次加热的合金组织

采用低频电磁铸造技术制备ZL201合金半固态坯料,研究了电磁场频率以及二次加热温度和保温时间对合金微观组织的影响.结果表明,随着电磁场频率从10 Hz增大到30 Hz,组织的枝晶化趋势逐渐减弱,当电磁场频率为30 Hz时,可以获得均匀、细小的蔷薇状和等轴晶组织.对电磁场频率为30 Hz时铸造的半固态坯料进行二次加热表明,当二次加热温度为630℃,保温20 min后,铸造组织逐渐转变为均匀的近球形组织,具有良好的触变成形性.     

大客车降噪的研究

运用噪声分离、频谱分析等技术手段,找出了GZ6921型后置柴油机大客车噪声超过国家标准的原因,并对主要噪声源及其频谱分布进行了分析对各主要噪声源－排气系统、冷却系统和发动机舱采取相应的降噪措施,如降低风扇转速,改善抗性消声器的降噪能力,修改冷却风进风道,平衡车两侧的噪声源,在发动机舱中粘贴吸音材料等。改进后GZ6921型大客车最大加速度时的车外噪声由91．5dB(A)降到86dB（A)以下,达到国际GB1495－75“机动车允许噪声”的规定。     

二冷区辊式电磁搅拌的模拟研究

利用ANSYS和CFX商业软件,对304不锈钢板坯连铸二冷区辊式电磁搅拌进行了模拟研究。结果表明,单向流动型搅拌时,板坯中心点磁感应强度最大,且频率每增加1 Hz,磁感应强度减小约2.92 m T;对于相向流动型搅拌,板坯断面中心线两端磁感应强度较大,中心点处最小;频率增加,板坯断面中心线上电磁力增大,且从3 Hz增加到7 Hz时,改变频率对电磁力的影响逐渐减弱;单向流动型搅拌时,板坯宽面中心截面形成两个对称分布的漩涡流场,对于板坯中心附近钢液,频率从3 Hz增加到7 Hz,流速增大约150 mm·s-1,坯壳厚度从30mm增加到50 mm,流速减小约60 mm·s~(-1);相向流动型搅拌时,板坯宽面中心截面形成四个漩涡流场,搅拌区域较小,强度较弱,对于板坯长度方向1/4附近钢液,频率从3 Hz增加到7 Hz,流速增大约180 mm·s-1;坯壳厚度从30 mm增加到50 mm,流速减小约70 mm·s~(-1)。     

污泥热解和气化过程中NO_x前驱物的释放特性

利用固定床反应器对3种取自广州和武汉城市污水处理厂的污泥(GZ,LWZ和NTZH)进行了系统的热解和气化试验,采用傅里叶变换红外光谱仪(FT-IR)在线检测热解气体产物中的含氮组分,分析各种气相含N组分的释放规律.实验结果表明:GZ,LWZ和NTZH污泥热解释放大部分NO,NH3和HCN的温度范围分别为320～600,200～700和300～800℃;LWZ污泥热解过程中生成的NH3,HCN和NO量最多;Ar和O2混合气(O2体积分数为4%)气氛下气化时,GZ,LWZ和NTZH污泥NO开始快速生成的温度比热解时分别提高约200,400和250℃,NO的生成量分别为热解时的4.30,2.34和3.93倍;NH3开始快速生成的温度与热解时基本相同,NH3的生成量分别为热解时的67%,1.37倍和95%;HCN生成完成时的温度比热解时分别低约400,100和200℃,HCN的生成量分别为热解时的1.10倍,1.21倍和95%.     

自然通风条件下热舒适性的模拟分析

采用基于CFD理论的Airpak软件对自然通风(正弦周期性波动的风速)条件下的热舒适性进行模拟分析,通过预测平均热感觉(PMV)指标和不满意率(PD)指标对热舒适性进行评价,比较人体对低频(0.3、 0.4、0.5 Hz)变化风速的满意度.结果表明,在室内温度、相对湿度等条件不变时,PMV值与风速呈现出相同的变化规律,人体对变化频率为0.3 Hz的风速最满意.     

4个不同地区十字花科根肿病菌生理小种鉴定及甘蓝新组合的抗性鉴定

采用Willimas鉴别系统对采自重庆市涪陵区、四川省成都市新都区、云南省昆明市嵩明县、四川省攀枝花市盐边县的4份根肿病菌菌样进行生理小种鉴定,结果表明：4个地区生理小种分别为4号,11号,7号,7号。利用田间自然鉴定法在4号为优势小种的重庆市涪陵区发病区对79个甘蓝新组合进行了抗性鉴定,其中表现高抗、抗病、耐病和感病的分别有8,20,20,31个。从中选择8个具有抗性且经济性状较优良的组合进行室内接种鉴定,结果表明：甘蓝新组合GZ04,GZ09,GZ40,GZ76和GZ80为耐病杂种组合,GZ03,GZ19和GZ78为抗病杂种组合,其中GZ78表现为高抗。     

不同硬段型水性聚氨酯胶黏剂的合成和性能比较

 用异佛尔酮二异氰酸酯（IPDI）/甲苯二异氰酸酯（TDI）、聚醚二元醇（N210）、二羟甲基丙酸（DMPA）为原料,采用两步法合成了不同硬段型聚氨酯预聚体,并用含三乙胺的去离子水中和乳化,乙二胺扩链,得TDI型和IPDI型水性聚氨酯（WPU）胶黏剂。通过红外、黏度、热重等分析方法,对不同硬段型WPU乳液、胶膜进行了结构和性能考查,对异氰酸酯基（NCO）含量进行定量、定性分析。结果表明,随着反应的进行NCO含量逐渐减少,至200min时基本达到理论值。当DMPA含量分别为3.0%（W/W）和8.0%（W/W）时,得到的TDI型和IPDI型WPU稳定、透明、耐溶剂性相对较好;此条件下的黏度分别为2000和6950mPa·s;两者的热稳定性都较好,起始分解温度分别达到350.8和295.0℃;IPDI型WPU机械强度高,拉伸强度为3.37MPa。综合比较各种性能,IPDI型WPU胶黏剂相对较佳。     

安徽高校高水平运动员听觉能力特征及差异性研究

采用BD-II-116型听觉实验仪,对32名不同专项和性别的安徽高校高水平运动员的听觉能力进行测试,对不同频率乐音的听觉能力特点和差异性进行分析.结果表明:(1)田径和体育舞蹈、田径和球类、球类和武术高水平运动员在512 Hz和2000 Hz,响度绝对阈限值差异性显著;(2)田径和武术、体育舞蹈和武术高水平运动员在512 Hz、1000 Hz、2000 Hz、4000 Hz和8000 Hz,响度绝对阈限值差异性不显著;(3)体育舞蹈和球类高水平运动员在512 Hz、4000 Hz,响度绝对阈限值差异性显著,而在1000 Hz、2000 Hz和8000 Hz,响度绝对阈限值差异性不显著.     

多曲盘旋转雾化装置设计及振动试验

旋转圆盘雾化器广泛用于工业领域.设计了一种多曲盘旋转雾化装置,介绍了装置的整体设计方案和主要结构参数的确定,并对电机不同工作频率下装置的振动特性进行了试验.结果表明:装置的最大振动位移在装置水平方向,为10 Hz时的0.308 mm;最大振动速度在装置垂直方向,为35 Hz时的11.9 m/s;最大振动加速度在装置垂直方向,为40 Hz时的10.5 m/s2.装置在10 Hz以及35～50 Hz范围内运行时存在较大振动;在15～30 Hz范围内运行相对较为平稳,建议装置在此范围内运行;装置在垂直方向上振动较为明显,应增添垂直方向上约束以实现装置的减振.     

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.     

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.     

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     

On the Thermodynamic Limit for Responses to Static Electromagnetic Fields

For molecular systems,the quantum-mechanical treatment of their responses to static electromagnetic fields usually employs a scalar-potential treatment of the electric field and a vector-potential treatment of the magnetic field.Although the potential for each field separately is associated with the choice of an(unphysical)origin,the precise choice of the origin for the electrostatic field has little consequences for the results.This is different for the     

An affordable accurate evaluation of the binding conformations predicted by molecular docking studies in bio-system

Franck-Condon factors bridge the gap between theoretical modeling and experimental observations for molecular electronic spectroscopy and electron transfer.Under the displaced harmonic oscillator approximation,multidimensional Franck-Condon factors are decomposed into a product of many one-dimensional(1D)Franck-Condon(FC)factors,and each 1D-FC factor is associated with one Huang-Rhys factor that determines the leading contribution of     

Call for Papers

<正>"The Journal of Shanghai Normal University:Mathematics"is published by Shanghai Normal University as regular issues of The Journal of Shanghai Normal University each year from 2014 in English.The editors-in-chief of the issues are professors Yuhao Cong and Maoan Han.The Journal of Shanghai Normal University was started in 1958 with     

Journal of Donghua University ( English Edition) Contents of Volume 31

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