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1.
RE1—xTxMnO3氧化物的结构,电磁特性和巨磁电阻   总被引:37,自引:0,他引:37  
REMnO3(RE=La,Pr,Nd,Cd等)具有钙钛矿结构。如用二价碱土金属部分替代稀土元素,可形成掺杂锰氧化物RE1-xTxMnO3(T=Ca,Sr,Ba,Pb)。随掺杂量的增加,样品的结构和电磁性能都有很大变化。近年来在这类氧化物中还发现巨大的负磁电阻效应,其值可达106%。这类材料显示的复杂物理现象和可能的应用前景引起人们很大的兴趣。本文将概括的介绍这类氧化物的晶格结构,电子结构,电磁性能及其巨磁电阻随掺杂变化的实验结果,并对其可能的机理进行探讨。  相似文献   

2.
通过SCC-DV-Xα方法对M4S6+电子结构和光谱性质的计算研究得出Clusters的第一吸收峰;同时,对M4S6+的稳定性、电荷转移及轨道成分对LUMO和HOMO的影响进行了讨论。  相似文献   

3.
通过SCC-DV-Xα方法对M4S^6+电子结构和光谱性质的计算研究得出Clusters的第一吸收峰;同时,对M4S^6+的稳定性,电荷转移及轨道成分对LUMO和HOMO的影响进行了讨论。  相似文献   

4.
万国宾  万伟  沈喆  周其忠 《计算物理》2000,17(6):619-624
应用物理光学法(PO)对天线-罩系统的散射特性进行了分析。通过对罩壁的局部平板等效,导出了天线表面的感应电流和罩表面的等效电、磁流分布的计算公式。以口径天线-多层介质结构雷达罩为例,计算了天线、雷达罩及天线-罩系统的单、双站雷达散射截面(RCS),并研究了当照射波频率和天线扫描角变化时RCS的变化规律。  相似文献   

5.
应用LAS-2000辐照设备、射频离子源设备及HL-1M装置对等离子体与石墨及其涂层的相互作用进行了系统研究,为进一步优化HL-1M装置原位处理工艺、杂质控制以及HL-2A装置第一壁的选材和第一壁处理、杂质控制等提供依据。  相似文献   

6.
动用BISON,FDKR和DOSE程序,计算了实验混合堆FEB在额定功率下运行一年后装置的第一壁,包层和屏蔽层的远距离维修指标RMR值和有关结果。结果表明,需在现有屏蔽设计基础上适当增加铅屏蔽层厚度,才能满足美国核管理委员会的10CFR20法规规定的辐射安全要求。计算结果可供实验混合堆的工程设计,安全运行及维修操作设计参考。  相似文献   

7.
SERS活性体系中光吸收带电磁和化学增强机制归属的认证研究方炎王四海(首都师范大学综合技术研究所,北京100037)AssignmentofEMandCTEnhancementsonOpticalAbsorptionSpectraofColoidal...  相似文献   

8.
PdO引入对CuO/γ—Al2O3催化剂结构与性能的影响   总被引:1,自引:0,他引:1  
运用PTR,SEM,XRD阶梯扫描及CO和CH4氧化活性测定表征技术研究了CuO/γ-Al2O3催化剂及负载PdO对催化剂性能的影响。结果表明,CuO/γ-Al2O3催化剂上引入不同含量的PdO,使TPR还原峰温欠下降。对载体上CuO平均晶粒大小的测定表明随PdO含量的增加,CuO平均晶粒逐渐减小;SEM对PdO-CuO/γ-Al2O3催化剂上Cu元素分布的面扫描测定亦证实了随PdO含量的增加,催  相似文献   

9.
用精确控制法计算复杂区域的二维电磁散射场   总被引:1,自引:1,他引:0  
陈红全  黄明恪 《计算物理》2000,17(4):414-420
描述二维电磁场的Maxwell方程(TM模态)可转化为等价的波动方程采用精确控制法计算该波动方程的时间周期角,数值模拟了包括外挂、鼓包以及舱体干扰的复杂气动外形电磁散射场,并计算给出了对应的雷达散射截面(RCS)。由于采用了非结构的三角形网格,特别适合计算复杂的实用气动外形。  相似文献   

10.
SHOCKCOMPRESSIONBEHAVIOROFBROMOFORMPengShangqianga,b,cJingFuqiana,bHuJinbiaoa,bGouQingquanba.LabforShockWaveandDetonationPhy...  相似文献   

11.
Ku波段光子晶体加载曲折波导慢波结构   总被引:2,自引:2,他引:0       下载免费PDF全文
研究了Ku波段光子晶体加载曲折波导慢波结构的色散特性和耦合阻抗。用电磁仿真软件CST MWS进行了仿真, 讨论了慢波结构外光子晶体对慢波通道内电磁波的选择通过性。对具有相同结构尺寸慢波结构的研究结果表明:光子晶体加载慢波结构的色散比传统曲折波导慢波结构的色散低;和传统曲折波导慢波结构相比,光子晶体加载曲折波导慢波结构的耦合阻抗略高。  相似文献   

12.
In this paper, a 1D nonlinear plasma photonic crystal (NPPC) structure composed of polarized ferroelectric crystals and nonlinear plasma periodic alternation is proposed. The transfer matrix method is employed to analyze the second harmonic generation (SHG) problem of this structure. In the designed NPPCs, the fundamental wave (FW) operates in the gigahertz (GHz) band and the nonlinear plasma is controlled by an external high-intensity control wave (CW). Numerical simulations are performed to investigate the effects of different incident angles and external CW intensities on the total conversion efficiency (T-con) of the second harmonic wave (SHW). Additionally, the internal electric field distribution and incident light intensity within the nonlinear structure are analyzed. The importance of the relationship between the FW frequency and photonic band gap (PBG) in enhancing SHG is summarized. The results demonstrate that the optimal structure can be obtained by changing the structural parameters, such that the FW and SHW are tuned to the edge of the PBG. At this point, the electromagnetic field density is large, the group velocity is small, the local field is enhanced, and the nonlinear optical interaction is increased, resulting in a significant increase in the T-con of the SHW.  相似文献   

13.
When the Foldy-Wouthuysen (FW) transformation is exact and the particle energy is positive, upper spinors in the Dirac and FW representations differ only by a constant factor, and lower spinors in the FW representation are zero. Deducing FW wave eigenfunctions directly from Dirac wave eigenfunctions allows one to use the FW representation to calculate expectation values of needed operators and to derive quantum and semiclassical equations of motion. The text was submitted by the author in English.  相似文献   

14.
应用ICP-MS测定不同种类蜂蜜中的微量元素和重金属   总被引:5,自引:0,他引:5  
蜂蜜含有丰富的人体必需的微量元素,但是不同品种蜂蜜间微量元素的含量差别研究较少。应用ICP-MS分析了不同蜂蜜种类中微量元素和重金属的含量。结果表明蜂蜜中含有丰富的Ca,Fe,Zn,Mn,Cu,Se和Mo等微量元素,不同品种间差别较大。所测定的六种蜂蜜中Ca,Fe,Zn,Mn,Cu,Se和Mo含量最高的分别是枣花蜜、枸杞蜜、苦瓜蜜、苦瓜蜜、荔枝蜜、荔枝蜜和枸杞蜜,达到了132.79,24.38,4.60μg.g-1.FW,2 930.10,480.02,29.39和3.45 ng.g-1.FW。各种蜂蜜中重金属的含量较少,As和Pb的含量在30 ng.g-1.FW以下,Hg,Cd和Cr的含量更低,在10 ng.g-1.FW以下,且品种间差别不大。说明蜂蜜营养丰富,食用安全性高,但是不同人群应当根据需要选择适合自己的品种。  相似文献   

15.
ITER TBM第一壁制造方法与样件试制   总被引:2,自引:0,他引:2  
介绍了ITER实验包层模块(TBM)第一壁(FW)的四种加工方式,并且采用其中一种铣槽—电子束焊接—折弯法,用304不锈钢加工了一个FW验证件.对制成的FW样件沿流道切割开,测得弯曲处最小流道面积为弯曲前的85%,弯曲处流道外侧壁厚的减薄较明显,但可以通过机械加工的方法来控制.为了进一步证实这种加工方式的可行性,下一步...  相似文献   

16.
In this paper,the basic equations of beam-wave interaction for designing the 220 GHz folded waveguide(FW)backward wave oscillator(BWO) are described.On the whole,these equations are mainly classified into small signal model(SSM),large signal model(LSM),and simplified small signal model(SSSM).Using these linear and nonlinear one-dimensional(1D) models,the oscillation characteristics of the FW BWO of a given configuration of slow wave structure(SWS) can be calculated by numerical iteration algorithm,which is more time efficient than three-dimensional(3D)particle-in-cell(PIC) simulation.The SSSM expressed by analytical formulas is innovatively derived for determining the initial values of the FW SWS conveniently.The dispersion characteristics of the FW are obtained by equivalent circuit analysis.The space charge effect,the end reflection effect,the lossy wall effect,and the relativistic effect are all considered in our models to offer more accurate results.The design process of the FW BWO tube with output power of watt scale in a frequency range between 215 GHz and 225 GHz based on these 1D models is demonstrated.The 3D PIC method is adopted to verify the theoretical design results,which shows that they are in good agreement with each other.  相似文献   

17.
The aim of this study was to evaluate the changes of ultrasound-assisted thawing on lamb meat quality and differential metabolite profiles during refrigerated storage. Compared with flow water thawing (FW), pH, a*, C*, and sulfhydryl content of lamb were significantly increased, while L*, drip loss and cooking loss were significantly decreased after ultrasound-assisted thawing (UT). On day 1 (UT1 and FW1) and day 7 (UT7 and FW7) in the UT and FW groups, principal component analysis explained 42.22% and 39.25% of the total variance. In this study, 44 (UT1 and FW1) and 47 (UT7 and FW7) differentially expressed metabolites were identified, including amino acids, carbohydrates and their conjugates, nucleic acids, carbonyl compounds and others. The results of this study provide data to clarify the differences between UT and FW, and lay a foundation for the application of ultrasound-assisted thawing in the meat industry.  相似文献   

18.
5FW 软X光胶片响应在同步辐射源上的实验标定   总被引:4,自引:2,他引:2       下载免费PDF全文
 介绍了5FW 软X-光胶片在同步辐射源上进行响应标定的一种实验方法, 得到了5FW 软X-光胶片对波长为1. 47nm 和4. 59nm 软X 光的相对响应实验曲线, 并与用理论模型计算的结果进行了比较。  相似文献   

19.
A novel Ka-band folded waveguide (FW) amplifier for traveling wave tubes (TWT) is investigated. The dispersion curve and interaction impedance are obtained and compared to the normal FW circuit by numerical simulation. The interaction impedance is higher than a normal circuit through the whole band. We also study the beamwave interaction in this novel circuit, and the nonlinear large-signal performance is analyzed by a 3-D particlein-cell code MAGIC3D. A much higher continuous-wave (CW) output power with a considerably shorter circuit compared to a normal circuit is predicted by our simulation. Moreover, the novel FW even has a broader 3-dB bandwidth. It therefore will be useful in designing a miniature but high-power and broadband millimeter-wave TWT.  相似文献   

20.
Based on the CH HCCB TBM design, the detail of the new modified first wall (FW) was described, and a series related analysis was conducted to compare with former design. In the preliminary analysis, the modified FW design shows much more advantages in comparison with the former design. The working conditions of the analysis have been set to ITER design condition. The performances and the results obtained from thermo-hydraulics and stress analysis are presented.  相似文献   

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