一种无线语音传输系统设计

利用锁相环技术,通过调频方式,实现音频信号的调制、解调,设计一种可以选择使用耳机或扬声器的无线语音传输系统.系统利用电路实现语音的通信和信息转发,可实现对语音实时无失真传输,系统实现对音频信号的无线通信的功能.     

机载大规模复杂软件开发及验证技术

针对航空电子系统结构综合化、硬件共享化、功能软件化引发软件规模、复杂度指数级上升的趋势,分析了软件开发、软件综合以及软件测试的困难和挑战,并从开发技术、测试验证技术和项目管理3个维度,结合模型驱动开发、软件复用、虚拟仿真验证、DO-297规范、CMMI等技术和管理方法,为机载大规模复杂软件开发及验证提供了解决方案,提高软件的可靠性,缩短软件的研发周期。     

面向航空电子系统的网络文件系统设计

针对IMA的多个应用模块的文件共享问题,基于具有自主知识产权的机载多分区实时OS平台,提出了一种网络文件系统NFS的设计方案。文中采用网络文件锁,通过对文件的上锁和解锁,实现多个分区互斥访问文件;使用权限验证机制验证用户对文件的访问权限,用户通过验证后方可对文件执行相应的操作;日志文件保存整个NFS的运行情况,用于对NFS性能的分析。文中阐述了NFS客户端、服务器端的设计和网络封装格式,并给出了NFS运行的原理图。     

铝-RIE刻蚀工艺

干法刻铝中 ,BCl3添加 Cl2 、CHCl3和 N2 ,可改变 Al的刻蚀速率、Al对 Si O2 和胶的选择性、线宽和胶膜质量 ,其中 Cl2 流量影响最大。此外 ,本文还给出 RF功率和气压的影响。采用适当的气体组合、不太高的功率和不太低的气压 (BCl3∶ Cl2 ∶ CHCl3∶ N2 =70 sccm∶ 1 5 sccm∶ 1 0 sccm∶ 0～ 5 0 sccm,2 0 0 m Torr,2 0 0 W)可以实现细线条 (0 .6μm) Al的刻蚀。     

LD泵浦的声光调Q腔内倍频固体激光器

应用国产的８０８ｎｍ激光二极管（ＬＤ）研制了声光调Ｑ的Ｎｄ：ＹＶＯ４－ＫＴＰ腔内倍频的准连续、单脉冲激光器,得到了ＴＥＭ００模、频率为２０ｋＨｚ的准连续稳定的５３２ｎｍ原绿光输出,阈值泵浦功率为３００ｍＷ。在连续２Ｗ的泵浦功率下,准连续绿光输出为１２０ｍＷ,脉冲宽度为４０ｎｓ,单脉冲能量为５０μＪ,通过对声光Ｑ开关的驱动电源改造,得到了单脉冲激光输出。在分析计算的基础上,建立了２Ｗ、８０８ｎｍＬＤ     

A direct digital frequency synthesizer with high-speed current-steering DAC

A high-speed SiGe BiCMOS direct digital frequency synthesizer (DDS) is presented. The design in tegrates a high-speed digital DDS core, a high-speed differential current-steering mode 10-bit D/A converter, a serial/parallel interface, and clock control logic. The DDS design is processed in 0.35 μm SiGe BiCMOS standard process technology and worked at 1 GHz system frequency. The measured results show that the DDS is capable of generating a frequency-agile analog output sine wave up to 400+ MHz.     

Efficiency Roll‐Off in Blue Emitting Phosphorescent Organic Light Emitting Diodes with Carbazole Host Materials

The efficiency roll‐off in blue phosphorescent organic light emitting diodes (OLEDs) using different carbazole compounds as the host is systematically studied. While there is no significant difference in device efficiency, OLEDs using ter‐carbazole as the host show a reduction in efficiency roll‐off at high luminance. Data from transient photoluminescence and electroluminescence measurements show that the lower triplet–triplet annihilation (TTA) and triplet–polaron quenching (TPQ) rates in devices with the ter‐carbazole host compared with other carbazole hosts are the reasons for this reduced efficiency roll‐off. It is also found that the host materials with low glass transition temperatures are more susceptible to the efficiency roll‐off problem.     

Well‐Defined Protein‐Based Supramolecular Nanoparticles with Excellent MRI Abilities for Multifunctional Delivery Systems

Protein‐based nanoparticles are widely used for effective biomedical applications. The objective of this work is to design series of magnetic resonance imaging (MRI)‐visible cationic supramolecular nanoparticles (PGEA@BSA‐Ad/Gd³⁺) based on bovine serum albumin (BSA) and β‐cyclodextrin‐cored star ethanolamine‐functionalized poly(glycidyl methacrylate) (CD‐PGEA) in the presence of Gd³⁺ ions for multifunctional delivery systems. CD‐PGEA is prepared via atom transfer radical polymerization and ring‐opening reaction. It is found that in the absence of Gd³⁺ ions, CD‐PGEA does not well interact with adamantine‐modified BSA (BSA‐Ad). The well‐defined PGEA@BSA‐Ad/Gd³⁺ supramolecular nanoparticles could be produced through the synergistic actions of the host–guest and electrostatic self‐assemblies by mixing aqueous solutions of CD‐PGEA, BSA‐Ad, and Gd³⁺. In comparison with CD‐PGEA assembly units, such kinds of uniform PGEA@BSA‐Ad/Gd³⁺ supramolecular nanoparticles exhibit better pDNA condensation ability, lower cytotoxicity, higher gene transfection, and easier cellular uptake. In addition, PGEA@BSA‐Ad/Gd³⁺ also produces outstanding MRI abilities, much better than Magnevist (Gd‐diethylenetriaminepentacetate acid). The present design of protein–polymer supramolecular nanoparticles with MRI contrast agents would provide a new way for multifunctional gene/drug delivery systems.     

Controlled Growth and Reliable Thickness‐Dependent Properties of Organic–Inorganic Perovskite Platelet Crystal

Organolead halide perovskites (e.g., CH₃NH₃PbI₃) have caught tremendous attention for their excellent optoelectronic properties and applications, especially as the active material for solar cells. Perovskite crystal quality and dimension is crucial for the fabrication of high‐performance optoelectronic and photovoltaic devices. Herein the controlled synthesis of organolead halide perovskite CH₃NH₃PbI₃ nanoplatelets on SiO₂/Si substrates is investigated via a convenient two‐step vapor transport deposition technique. The thickness and size of the perovskite can be well‐controlled from few‐layers to hundred nanometers by altering the synthesis time and temperature. Raman characterizations reveal that the evolutions of Raman peaks are sensitive to the thickness. Furthermore, from the time‐resolved photoluminescence measurements, the best optoelectronic performance of the perovskite platelet is attributed with thickness of ≈30 nm to its dominant longest lifetime (≈4.5 ns) of perovskite excitons, which means lower surface traps or defects. This work supplies an alternative to the synthesis of high‐quality organic perovskite and their possible optoelectronic applications with the most suitable materials.     

激光金属直接制造中载气流量对薄壁零件成形质量的研究

对载气式激光金属直接制造中承载粉末的载气参数进行了实验研究,用316L不锈钢粉末进行了不同载气流量的薄壁零件的成型试验.实验结果表明,在送粉量一定时,随载气流量增大,薄壁零件的表面成形质量先增大后减小.通过选择适当的载气流量能够制造出薄壁零件顶端表面平整程度达到53.7μm,对于提高薄壁零件表面的成形精度具有指导意义.