新型反应性改性沥青改性剂技术性能研究

对不同种类改性沥青混合料进行了动态模量试验、小梁弯曲疲劳试验、动态蠕变拉伸试验和无侧限拉伸试验,通过对这四种试验结果进行分析研究,对比了不同种类改性沥青混合料的技术性能,评价了RET改性剂对沥青混合料路用性能的改善效果。     

卡塞格伦天线副反射面运动扫描研究

星载大口径反射面天线运动扫描中会产生较大干扰力矩,对卫星平台姿态稳定造成较大影响。研究了天线副反射面运动扫描技术,在卡塞格伦天线系统中固定主反射面和馈源系统,通过运动副反射面实现波束扫描。卡塞格伦天线副反射面扫描运动中,每个特定扫描角度存在方向图性能恶化程度最低的最佳副面位置,运用射线优化法对各扫描 角度对应的最佳副面位置进行求解。文中给出了设计流程,通过软件进行仿真设计,加工了天线测试系统并进行方向图测试,验证了设计方法的正确性。     

新一代STE分子束外延系统(英文)

Method of Molecular Beam Epitaxy (MBE) is based on the growth of semiconductor layers by effusion source components evaporation under ultrahigh vacuum (10～11 Torr), so the flow of growth components in space occurs in the molecular beam mode. To ensure UHV and the required purity of the process (besides oil-free pumping system: turbo molecular pumps, ion pumps, cryopumps), cryopanels built into the growth reactor and filled with liquid nitrogen are used. Sources and wafer strong heating, integrated research methods, necessity of precision wafer mechanical movement between chambers in UHV conditions mean the complexity of equipment. As a result, MBE systems are produced only by a few companies in USA and Europe. In Russia, serial production of such equipment begun in 80's but in mid 90's was widely discontinued.     

MIMO技术及在3G中的应用

介绍MIMO技术的定义和历史,从空间复用、传输分集技术、波束成型等方面对MIMO技术进行说明,并对MIMO在3G(HSPA+)中的应用做了简单的描述。     

D3-1000型整经机部分机构的改造实践

针对金丸D3-1000型整经机生产过程中存在的问题,进行了以下改造:用光电式断经自停装置取代触点式断经自停装置;改进了导纱钩形状,减少了经纱绞头疵点;对经轴夹盘磨损部位采取更换局部部件的方法,节约了维修费用;设计并加装了机前安全防护装置,实现了对生产人员的安全防护.     

JSSJ-83型小样浆纱机的改造

为解决JSSJ-83型小样浆纱机浆纱速度、烘燥温度、织轴卷绕张力控制不准确的问题,进行了技术改造.通过采用交流变频电机取代原直流电机、加装烘筒智能温控装置和织轴卷绕张力控制装置,并对无级变速器进行改造,提高了JSSJ-83型小样浆纱机的自动化程度.试验结果表明,改造后浆纱质量得到改善,卷装形式更利于取样操作.     

Statistical treatment of misalignments in particle accelerators

To know how much misalignment is tolerable for a particle accelerator is an important input for the design of these machines. In particle accelerators the beam must be guided and focused using bending magnets and magnetic lenses, respectively. The alignment of the lenses along a transport line aims to ensure that the beam passes through their optical axes and represents a critical point in the assembly of the machine. There are more and more accelerators in the world, many of which are very small machines. Because the existing literature and programs are mostly targeted for large machines, in this work we describe a method suitable for small machines. This method consists in determining statistically the alignment tolerance in a set of lenses. Differently from the methods used in standard simulation codes for particle accelerators, the statistical method we propose makes it possible to evaluate particle losses as a function of the alignment accuracy of the optical elements in a transport line. Results for 100 keV electrons, on the 3.5-m long conforming beam stage of the IFUSP Microtron are presented as an example of use.     

A Large Range Flexure-Based Servo System Supporting Precision Additive Manufacturing

This paper presents the design, development, and control of a large range beam flexure-based nano servo system for the micro-stereolithography (MSL) process. As a key enabler of high accuracy in this process, a compact desktop-size beam flexure-based nanopositioner was designed with millimeter range and nanometric motion quality. This beam flexure-based motion system is highly suitable for harsh operation conditions, as no assembly or maintenance is required during the operation. From a mechanism design viewpoint, a mirror-symmetric arrangement and appropriate redundant constraints are crucial to reduce undesired parasitic motion. Detailed finite element analysis (FEA) was conducted and showed satisfactory mechanical features. With the identified dynamic models of the nanopositioner, real-time control strategies were designed and implemented into the monolithically fabricated prototype system, demonstrating the enhanced tracking capability of the MSL process. The servo system has both a millimeter operating range and a root mean square (RMS) tracking error of about 80 nm for a circular trajectory.     

用积分变换法计算梁的弯曲变形

将积分变换方法与奇异函数相结合，用于计算各种等截面梁的弯曲弯形，计算过程简单，在工程设计中有一定的实用价值。     

HIGH RESOLUTION REAL-TIME MEDICAL IMAGING BASED ON PARALLEL BEAMFORMING TECHNIQUE

Improvement of frame-rate is very important for high quality ultrasound imaging of fast-moving structures.It is also one of the key technologies of Three-Dimension (3-D) real-time medical imaging.In th...