The Carnot efficiency enabled by complete degeneracies

Quantum-size effects unavoidably produce imperfect-regeneration heat losses in irreversible isothermal expansion/compression cycles, leading to the less efficiency of micro engines. Here, we design a smallest quantum Stirling-like heat engine using a single trapped electron as the working substance. The quantum probabilities to determine the electronic position are constructed from the incoherent mixed ensemble. When the quantum well expands isothermally to double its size and an infinite delta-function potential barrier is inserted in the middle, the complete degeneracies enable the heat engine to work reversibly and achieve the Carnot efficiency. The proposed theoretical model can open up new avenues for building practical nano-energy devices.     

基于CouchDB和Elastic Search的高性能化学结构搜索引擎与数据库的构建

计算机辅助的化学结构搜索在化学信息学中地位十分重要,本文设计了一套高性能的化学结构和化学数据搜索系统,称为DCAIKU.DCAIKU基于CouchDB无模式数据库和ElasticSearch基础架构构建,通过将结构相似性搜索变换为文字搜索实现了高性能和高灵活性的检索引擎：在满足化学信息存储的高灵活性条件下,仍然可以做到低延迟和高准确性,同时拥有良好的伸缩性,可以大规模并行化和集群化.     

基于设备结构分解的可视化故障推理与诊断技术研究

通过定义热区和热区索引,将故障推理与诊断同设备结构分解相对应,在诊断的过程中构建了故障自动推理编码规则,可将故障树转换成一系列可操作的且具有一定逻辑关系的编码,实现可视化故障自动推理和诊断。通过某型电子装备进行故障推理实例验证,表明该方法层次结构清晰,推理简单有效,能够实现装备可视化的LRU级分层故障诊断和故障的快速定位。     

柴油机轴系扭振系统的强非线性主共振

研究柴油机轴系扭振系统强非线性问题.根据拉格朗日方程建立柴油机轴系扭振系统的动力学模型,通过参数变换,应用Modified Lindstedt-Poincaré方法得到柴油机轴系扭振系统强非线性主共振的幅频响应方程,分析系统不同参数对主共振幅频响应的影响.结果表明,系统的幅频响应曲线存在跳跃,随着简谐力矩的减小和阻尼的增大,系统的非线性跳跃减弱,系统的振幅减小,系统主共振的区域也随之减小;随着调谐参数的变化,系统的主共振力幅响应曲线存在两种拓扑结构.MLP方法得出的近似解析解与龙格库塔法得出的数值解吻合.     

Theoretical and experimental investigation of onset characteristics of standing-wave thermoacoustic engines based on thermodynamic analysis

A simplified physical model for calculating the onset temperature ratio and the frequency of a standing wave thermoacoustic engine (SWTE) in the time domain is built based on thermodynamic analysis. Coefficients of transient pressure drop and heat transfer are first deduced from linear thermoacoustic theory. By numerical computation, the evolutions of the pressure amplitude and the spectrum characteristics during the onset process are presented. Furthermore, the effects of stack spacing, charge pressure, and resonator length on the onset temperature ratio and the frequency are calculated. Relatively good agreement between the computational and the experimental results has been achieved, which validates the model for calculating the onset characteristics.     

Design of fly's-eye lens for LCOS laser display

Design of optical system in laser display has always been an important research topic. From the aspect of decreasing the system volume and improving the light efficiency, it can be found that when the size of fly's-eye lens and the value of f/# are definite, the more fly's-eye arrays there are, the more useful it will be to the decrease of the optical engine size, which means that more honeycombs on fly's-eye lens and better dodging effect can be more beneficial for the decrease of the system size. After the optimal design for the rectangular elements on sub-fly's-eye lens and then doing 4000 ray tracing, the light transmittance turns out to be good with little parasitic light and scattering light.     

一种云环境下的发动机健康管理系统及其应用

针对航空公司对大量飞机发动机进行健康管理的需求,通过建立发动机健康管理云端数据中心,建立了一种云环境下的民航发动机健康管理系统,该系统对于验证发动机故障诊断方法的有效性具有突出优势,并且对于实现多种方法协同进行发动机故障诊断具有重要价值;提出了一种基于灰色关联分析的灰色故障识别方法,通过在云端平台使用灰色故障识别方法实现JT9D-7R4发动机的典型气路性能故障诊断为例,表明云环境下的发动机健康管理系统可以有效地进行航空发动机故障诊断。     

激光投影显示中光棒匀光的照明光路设计

在方棒照明系统的基础上,根据激光光源的发光特性和准直性,设计了一款用于激光投影显示的,基于光棒匀光的照明光路系统。此系统具有结构简单、开发周期短、加工成本低的优点。仿真结果表明:设计的激光投影机光能量利用率达到78%,均匀度达到85%,满足激光投影显示中对集光和照明的设计要求。     

Influence of an indefinite causal order on an Otto heat engine

The quantum effect plays an important role in quantum thermodynamics, and recently the application of an indefinite causal order to quantum thermodynamics has attracted much attention. Based on two trapped ions, we propose a scheme to add an indefinite causal order to the isochoric cooling stroke of an Otto engine through reservoir engineering. Then, we observe that the quasi-static efficiency of this heat engine is far beyond the efficiency of a normal Otto heat engine and may reach one. When the power is its maximum, the efficiency is also much higher than that of a normal Otto heat engine. This enhancement may originate from the non-equilibrium of the reservoir and the measurement on the control qubit.     

Online characterization of regulated and unregulated gaseous and particulate exhaust emissions from two-stroke mopeds: A chemometric approach

Two-stroke mopeds are a popular and convenient mean of transport in particular in the highly populated cities. These vehicles can emit potentially toxic gaseous and aerosol pollutants due to their engine technology. The legislative measurements of moped emissions are based on offline methods; however, the online characterization of gas and particulate phases offers great possibilities to understand aerosol formation mechanism and to adapt future emission standards. The purpose of this work was to study the emission behavior of two mopeds complying with different European emission standards (EURO-1 and EURO-2). A sophisticated set of online analyzers was applied to simultaneously monitor the gas phase and particulate phase of exhaust on a real time basis. The gaseous emission was analyzed with a high resolution Fourier transform infrared spectrometer (FTIR; nitrogen species) and a resonance-enhanced multiphoton ionization time-of-flight mass spectrometer (REMPI-ToF-MS; polycyclic aromatic hydrocarbons: PAH), whereas the particulate phase was chemically characterized by a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS; organic, nitrate and chloride aerosol) and a multiangle absorption photometer (MAAP; black carbon). The physical characterization of the aerosol was carried out with a condensation particle counter (CPC; particle number concentration) and a fast mobility particle sizer (FMPS; size distribution in real time). In order to extract underlying correlation between gas and solid emissions, principal component analysis was applied to the comprehensive online dataset. Multivariate analysis highlighted the considerable effect of the exhaust temperature on the particles and heavy PAH emissions. The results showed that the after-treatment used to comply with the latest EURO-2 emission standard may be responsible for the production of more potentially harmful particles compared to the EURO-1 moped emissions.