熔融温度对IBC合金性能的影响

采用阳极极化、恒流放电和析气等方法,研究熔融温度对IBC系锌合金电极和锌合金粉电化学性能的影响;采用扫描电子显微镜(SEM)对不同熔融温度条件下制备的IBC系锌合金粉进行形貌观察。结果表明:熔锌温度影响合金的分布状态、电化学活性等性能,当熔融温度为500℃时,IBC锌合金粉具有较均匀的粒度分布且表面形态一致,在150mA恒流连续放电时,锌负极活性物质的利用率为66.34%。     

锂离子电芯一致性对电池组影响的研究

通过对锂离子串并联组合电池中单体电芯的不一致性研究,分析并联电池组中的主要影响因素DCR对电池组造成的影响程度和串联电池组的主要影响因素容量对电池组造成的影响程度,为组合电池包提供必要的依据。     

BaO掺杂对高频MnZn功率铁氧体性能的影响

采用氧化物陶瓷工艺制备Mn Zn铁氧体,研究了Ba O掺杂量对高频Mn Zn功率铁氧体微观结构和磁性能的影响。结果表明,少量的Ba O掺杂可以使铁氧体烧结样品的晶粒尺寸增大,密度和饱和磁感应强度提高,功耗降低,而过量加入后会出现过烧现象,功耗增加,饱和磁通密度和密度有所下降。烧结样品的起始磁导率随Ba O掺杂量的增加单调下降。在1260℃烧结温度下,当Ba O掺杂量为0.025wt%时,样品具有最低功耗值,且其他磁性能也较好。另外,与不掺杂Ba O的最佳烧结条件下铁氧体样品相比,1260℃烧结掺杂量为0.025wt%的材料起始磁导率降低,但功耗的温度特性更优。     

烧结温度对超低损耗锰锌铁氧体性能的影响

使用同一配方制备得到的锰锌铁氧体坯件分别在1360℃、1330℃、1300℃下采用平衡气氛法烧结,制备得到致密的锰锌铁氧体磁环。SEM结果表明,降低烧结温度有效地减小了晶粒尺寸,消除了晶粒内部气孔,改善了晶粒均匀程度,使晶界更为清晰。电磁性能测试表明,在三种温度烧结得到的锰锌铁氧体材料的起始磁导率μi没有显著差异;饱和磁感应强度Bs随烧结温度降低有小幅上升;总功率损耗随烧结温度的降低而下降;并且在1300℃烧结的铁氧体材料的功率损耗(100k Hz/200m T,100℃)很低,约为255k W/m~3。通过损耗分离证实,总功率损耗的改善主要是涡流损耗大幅降低所致。     

Number and density of states in quantum semiconductor structures

Pushed by the semiconductor industry to achieve greater speed and functionality, device dimensions are becoming sufficiently small to exhibit prominent quantum mechanical effects. In addition, devices are now being developed that utilize these quantum effects. The number and density of states are fundamentally important in the operation of any quantum device. Traditionally in a classroom setting, one-dimensional (1-D), two-dimensional (2-D), and three-dimensional (3-D) continuum approximations are presented to analyze the quantum wire, well, and box, respectively. As shown in this paper, the exact number and density of states can be straightforwardly calculated by students for real semiconductor quantum structures. These results clearly illustrate the overall true 3-D form of each of these structures. These correct calculations also reveal an overestimation in the number of states when using the continuum approximations     

Effects of compression on soft tissue optical properties

Tissue optical properties are necessary parameters for prescribing light dosimetry in photomedicine. In many diagnostic or therapeutic applications where optical fiber probes are used, pressure is often applied to the tissue to reduce index mismatch and increase light transmittance. In this paper, we have measured in vitro optical properties as a function of pressure with a visible-IR spectrophotometer. A spectral range of 400-1800 mm with a spectral resolution of 5 nm was used for all measurements. Skin specimens of a Hispanic donor and two Caucasian donors were obtained from the tissue bank. Bovine aorta and sclera, and porcine sclera came from a local slaughter house. Each specimen, sandwiched between microscope slides, was compressed by a spring-loaded apparatus. Then diffuse reflectance and transmittance of each sample were measured at no load and at approximately 0.1, 1, and 2 kgf/cm². Under compression, tissue thicknesses were reduced up to 78%. Generally speaking, the reflectance decreased while the overall transmittance increased under compression. The absorption and reduced scattering coefficients were calculated using the inverse adding doubling method. Compared with the no-load controls, there was an increase in absorption and scattering coefficients among most of the compressed specimens     

石墨粉的嵌锂性能及颗粒结构研究

研究了若干种通过不同制备方法获得的石墨粉的电化学嵌锂性能 ,得到一种高比容量的锂离子蓄电池负极材料 ,组装成扣式电池以 0 .32mA·cm-2 充放电时 ,前 10次平均放电比容量可达 35 5mAh·g-1。对各种石墨粉做了XRD、SEM和BET比表面积等结构测试 ,讨论了石墨颗粒的结构与其嵌锂性能的关系 ,认为石墨化度高、微晶尺寸小、颗粒内有大量微裂缝且粒径分布合理的石墨粉具有更高的可逆嵌锂容量。     

浆料酸值对钛酸钡电容器介电性能的影响

通过水煮溶液pH值及其电导率、电气强度、介电性能-温度特性、化学组成、陶瓷片表面显微结构等的测试分析．研究了固相反应合成钛酸钡(BaTiO3)粉体中．用氨水调高浆料的pH值对BaTiO3基电子陶瓷电容器的介电性能的影响。结果表明：pH值提高明显改善BaTiO3粉体的性能。在pH=10．3时,合成的BaTiO3中BaO含量降低了92．86％,电气强度提高了29．50％,介电常数峰值提高了15．41％。     

Boundary effects on the optical properties of InGaN multiple quantum wells

We examine the issues of spontaneous and piezoelectric polarization discontinuity on the optical properties of 3.0-nm-thick indium gallium nitride (InGaN) multiple quantum wells (MQWs). A quench of band-edge emission from the cap GaN layer is observed when the photoexcitation source is changed from a 355- to a 248-nm laser. The interband transitions from the InGaN wells exhibit a linear dependence on the 1) spectral blue shift of /spl sim/8.5/spl times/10/sup -18/ meV /spl middot/ cm/sup 3/ and 2) change of the internal field of /spl sim/3/spl times/10/sup -14/ meV /spl middot/ cm/sup 2/ with the injected carrier density up to N/sub inj//spl sim/10/sup 19/ cm/sup -3/ at 77 K. These observations are attributed to the redistribution of photogenerated carriers in the InGaN wells due to the polarization discontinuity at the QW interface and the surface band bending effect. By incorporating an additional boundary condition of surface Fermi-level pinning into the Poisson equation and the band-structure analysis, it is shown the emission from the InGaN-GaN MQWs is dominant by the recombination between the high-lying subbands and the screening of internal field effects.     

Exploring the optical properties of exposed-core-based photonic-crystal fibers

Journal of Computational Electronics - A photonic-crystal fiber (PCF) based on the surface plasmon resonance (SPR) effect with low confinement loss and high sensitivity response is designed and its...     

The electronic structures for the optical absorption of Hf-O-N thin films

The local structures of Hf-O-N thin films were analyzed using an extended X-ray absorption fine structure (EXAFS) study on Hf L _III-edge and first-principles calculations. Depending on their composition and atomic configurations, Hf₄O₈ (CN: 7.0), Hf₄O₅N₂ (CN: 6.25) and Hf₄O₂N₄(CN: 5.5) were suggested as the local structures of Hf-O-N thin films. The optical band gaps of Hf-O-N thin films were compared with the calculated band gap. And to investigate the optical absorption, the effects of film compositions on the valence bands of Hf-O-N thin films were analyzed by comparing the experimental valence band with the valence band.     

溶剂含水量对二苯甲烷双马来酰亚胺合成和性能的影响

用含水量不同的丙酮作溶剂,合成了二苯甲烷双马来酰亚胺(BDM)。用IR、DSC和测量副产物(BP)含量及凝胶化时间(GT)等方法,研究了合成物的结构和性能。结果表明,当溶剂中含水量<6%时,BDM产物随含水量增加而收率缓慢下降,但性能未明显变坏;而当含水量>6%时,在BDM收率显著下降的同时,有害的BP含量明显增加,BDM反应活性大大下降,质量严重下降。因此当用丙酮法生产BDM时,使用含水量低的丙酮是保证BDM质量的必要条件。     

热处理对Al-Mg-Sn-Ga-X合金阳极组织与电化学性能的影响

研究了Al-Mg-Sn-Ga-X五元铝合金阳极材料热处理对其在4mol/LNaOH+10g/LNa2SnO3介质中的微观组织和电化学性能的影响。利用金相显微镜、透射电镜、扫描电镜观察了显微组织和表面形貌,利用IM6ex型电化学综合测试仪和排水法测试了材料的电化学性能和腐蚀速率。结果表明:在4mol/LNaOH+10g/LNa2SnO3介质中,冷轧后的Al-Mg-Sn-Ga-X五元铝合金阳极板材经回复退火,可以降低其腐蚀速率,并且稳定工作电位负移,有效改善其综合电化学性能;再结晶退火,板材立方织构增多,其腐蚀速率增大,稳定工作电位负移。     

稀土La掺杂和退火温度对非晶磁芯软磁性能的影响

首先制备La掺杂Fe_(78)Si_9B_(13)合金(Fe Si B-La)非晶带材,然后绕制成环型磁芯,在不同温度下进行退火处理,研究La含量和退火温度对其软磁性能的影响。结果表明,随着La含量的增加,Fe Si B-La非晶磁芯的相对起始磁导率μ_i和饱和磁感应强度B_s呈先增大后减小的趋势,而矫顽力H_c呈先减小后增大的趋势。随着退火温度的升高,Fe Si B-La非晶磁芯的μ_i、B_s、H_c、电感L_s和品质因数Q呈先增大后减小的趋势。     

MoO_3掺杂对锰锌铁氧体显微结构与磁性能的影响

以Fe_2O_3、MnO、ZnO粉体为原料,采用固相烧结法,通过一次球磨,850℃预烧并掺杂,二次球磨,1200℃烧结最后压制成型制得不同MoO_3掺杂量的锰锌铁氧体,运用SEM、XRD、VSM等手段研究该材料的组织与性能。结果表明,无论是否掺杂MoO_3,均生成了典型的尖晶石铁氧体相和Fe_2O_3相。材料的饱和磁化强度和磁导率随掺杂量增加先增大后减小,矫顽力和剩余磁化强度先减小后增大。表现为掺杂0.06wt% MoO_3的锰锌铁氧块体组织最为致密,磁性能达到最优,矫顽力及剩余磁化强度最小,磁导率和饱和磁化强度最大。     

三维复杂无压渗流场求解方法研究

本文针对三维无压渗流问题提出了固定网格虚域迭代法 ,在此基础上引入加速迭代求解的不变网格丢单元法 ,该方法能在不变网格的基础上很好地适应强非线性问题自由面振荡及不易收敛的特点 ,同时研制了相应的算法和程序 ,算例计算对比表明 ,本文提出的方法在理论和算法上是正确的。将之应用于某双曲拱坝坝基渗流场分析 ,成功分析了坝基的渗流特性。     

不同结构光学电压互感器抗电场干扰的探讨

外电场对光学电压互感器(Optical Voltage Transformer,OVT)的干扰与OVT的结构有关系,通光方向和电压方向不同,外电场对OVT的影响也不同.该文详细分析了外电场对OVT的横向调制和纵向调制两种基本结构的影响.针对这两种结构抗电场干扰的特点,兼顾实际高电压测量中的信号处理,提出了一种OVT传感头结构的改进措施.     

不同结构光学电压互感器抗电场干扰的探讨

外电场对光学电压互感器(OpticalVoltageTransformer,OVT)的干扰与OVT的结构有关系,通光方向和电压方向不同,外电场对OVT的影响也不同。该文详细分析了外电场对OVT的横向调制和纵向调制两种基本结构的影响。针对这两种结构抗电场干扰的特点,兼顾实际高电压测量中的信号处理,提出了一种OVT传感头结构的改进措施。     

Modeling the optical properties of twisted bilayer photonic crystals

We demonstrate a photonic analog of twisted bilayer graphene that has ultra-flat photonic bands and exhibits extreme slow-light behavior. Our twisted bilayer ph...     

人工砂岩性和石粉含量对混凝土性能的影响

本文研究人工砂岩和石粉含量对混凝土性能的影响。研究发现,当配合比相同时,岩性对混凝土坍落度的影响轻微,但对含气量和抗压强度影响大。花岗岩人工砂混凝土的含气量最大,比石灰岩平均大1.4%;砂岩次之,比石灰岩平均大0.5%;石灰岩最小。石灰岩人工砂混凝土的抗压强度最大;砂岩次之,7d和28d龄期平均为灰岩人工砂混凝土的0.96倍和0.84倍;花岗岩最小,7d和28d龄期平均为灰岩人工砂混凝土的0.88倍和0.80倍。当配合比相同时,人工砂石粉含量增大,混凝土的含气量和坍落度线性减小,抗压强度线性增大,与岩性无关。石粉含量增大10%,含气量减小2.5%,坍落度平均减小5.5cm,抗压强度平均增大15.8%。