外电场下氨分子光谱与激发特性研究

利用筛选的B3PW91密度泛函方法在CC-PVQZ基组下优化出氨分子的基态稳定构型,并考察了不同外电场对NH₃分子的特性及红外光谱(IR)的影响,在此基础上利用TD-DFT考察了不同外电场对NH₃分子前9个激发态的影响.结果表明：电场由0 a.u.增加至0.04 a.u.时,NH₃的构型参数与电场强度有明显的依赖关系;总能量(E_T)呈下降的趋势;偶极矩(μ)呈增加的趋势;最高占据分子轨道(HOMO)的能级呈降低的趋势,最低空分子轨道(LUMO)的能级呈增加的趋势;能隙(E_G)呈增加的趋势,即外电场会影响NH₃参与化学反应的能力;IR在电场考察范围内的特征峰位置及强度均会受到电场的影响,即可利用电场对分子的IR进行调控,从而便于对相关谱图信息的捕捉;外电场对NH₃分子的激发能及振子强度均有影响,因此,可以利用外电场来调控NH₃的激发特性.     

泉州湾滨海退化湿地红树林修复工程对土壤酶活性的影响

以泉州湾滨海退化湿地为对象，通过野外调查、采样、实验室分析，初步研究红树林修复工程对土壤酶活性的影响。结果表明，退化湿地修复前土壤磷酸酶和脲酶活性分别为8.78~17.72 μg/(g?24 h)和45.86~80.12 μg/(g?24 h)，修复后土壤磷酸酶和脲酶活性分别为10.21~14.22 μg/(g?24 h)和85.83~102.22 μg/(g?24 h)。在秋茄+桐花树+红海榄修复模式下，土壤磷酸酶和脲酶活性均明显增高；在秋茄+桐花树+白骨壤修复模式下，土壤磷酸酶活性明显降低，脲酶活性有一定增高；在秋茄+桐花树+木榄修复模式下，土壤磷酸酶和脲酶活性变化均不明显。     

外电场下甲醛的分子光谱与解离特性研究

摘要：以CC-PVQZ为基组,采用筛选的B3LYP研究了不同外电场对CH2O分子基态结构、电荷分布、总能量、电偶极距、最高占据轨道(HOMO)能级、最低占据轨道(LUMO)能级、能隙、红外光谱、拉曼光谱及CH2O分子中1C-2H键解离的影响。研究表明：电场由-0.04 a.u.变化至0.04 a.u.时,CH2O的结构参数与电场有明显依赖关系;体系总能量呈下降趋势;偶极矩呈增加趋势;HOMO能级与LUMO能级均逐步降低;能隙则呈增加趋势,即CH2O参与化学反应的能力会受到电场的影响;红外与拉曼光谱在电场考察范围内均出现红移现象,且光谱强度还会受到电场的影响,即可利用电场对分子的红外及拉曼光谱进行调控,从而便于对相关谱图信息的捕捉;CH2O分子中的1C-2H键的束缚情况会受不同电场的影响,且1C-2H键解离势垒与电场具有极高相关性,研究结果为电场降解甲醛提供了重要的理论依据。     

Two-Dimensional Electron Gas with High Mobility Forming at BaO/SrTiO3 Interface

Two-dimensional electron gas （2DEG） with high electron mobility is highly desired to study the emergent properties and to enhance future device performance.Here we report the formation of 2DEG with high mobility at the interface between rock-salt Ba O and perovskite Sr Ti O₃.The interface consists of the ionically compensated Ba O_1-δlayer and the electronically compensated Ti O₂ layer,which is demonstrated as a perfect interface without lattice mismatch.The so-fo...     

Observation of large in-plane anisotropic transport in van der Waals semiconductor Nb2SiTe4

Two-dimensional (2D) van der Waals material is a focus of research for its widespread application in optoelectronics, memories, and spintronics. The ternary compound Nb₂SiTe₄ is a van der Waals semiconductor with excellent air stability and small cleavage energy, which is suitable for preparing a few layers counterpart to explore novel properties. Here, properties of bulk Nb₂SiTe₄ with large in-plane electrical anisotropy are demonstrated. It is found that hole carriers dominate at a temperature above 45 K with a carrier active energy of 31.3 meV. The carrier mobility measured at 100 K is about 213 cm²·V^-1·s^-1 in bulk Nb₂SiTe₄, higher than the reported results. In a thin flake Nb₂SiTe₄, the resistivity ratio between the crystalline axes of a and b is reaching about 47.3 at 2.5 K, indicating that there exists a large anisotropic transport behavior in their basal plane. These novel transport properties provide accurate information for modulating or utilizing Nb₂SiTe₄ for electronic device applications.     

维吾尔文研究与Android维文阅读器的实现

在研究Android平台文本排版显示引擎和维吾尔文特点的基础上，通过分析维吾尔文本在多款阅读器上显示时出现的问题，找出不支持显示维文文本的原因。最后根据维吾尔文特点进行分析并设计维文阅读器架构，该架构的核心是在阅读器应用层进行维文显示渲染引擎的设计。     

New Type of Nitrides with High Electrical and Thermal Conductivities

The nitrogen dimer as both a fundamental building unit in designing a new type of nitrides, and a material gene associated with high electrical and thermal conductivities is investigated by first principles calculations.The results indicate that the predicted Si N4 is structurally stable and reasonably energy-favored with a striking feature in its band structure that exhibits free electron-like energy dispersions. It possesses a high electrical conductivity(5.07 × 10~5 S/cm) and a high thermal conductivity(371 W/m·K) comparable to copper. The validity is tested by isostructural Al N4 and Si C_4. It is demonstrated that the nitrogen dimers can supply a high density of delocalized electrons in this new type of nitrides.     

基于wMPS和模糊控制的AGV路径规划控制

针对大空间自动导引车(AGV)的高精度路径规划控制应用,提出一种基于工作空间测量定位系统(wMPS)和模糊控制算法相结合的应用模式。事先规划好AGV路径,采用wMPS对AGV实时位姿进行精确测量,通过模糊控制算法输出实时调整AGV的前进速度和旋转角速度。算法仿真与实验结果表明,AGV的定位精度优于2.5 mm,能够保证AGV的动态导航和定位精度。     

喷水温度对内燃兰金循环燃烧过程影响的试验研究

内燃兰金循环发动机采用氧气代替空气作为助燃剂,规避了氮排放物,可以以较低成本通过冷凝过程分离废气中的水蒸气和二氧化碳,随后对二氧化碳进行回收,实现了采用化石燃料的超低排放循环.本文利用自主开发的内燃兰金循环发动机试验台架对喷水温度对燃烧过程的影响进行了试验研究。研究结果表明,在燃烧过程中喷入循环水可控制燃烧速率,使最大爆发压力后移。相同的喷水脉宽及喷射压力下,高喷水温度时发动机的IMEP显著高于低温喷水工况,较高的喷水温度可增加上止点附近进入缸内的焓值,故可通过提高喷水温度增加IMEP,进而提高循环热效率。