旋转式伽玛刀的辐射剂量学

旋转式伽玛刀的辐射剂量学指标的物理测试在放射性医疗设备投放医院正式临床使用前是必不可少的，是对设备及其附件的设计、加工制造、安装以及电气控制系统等的全面综合性检定。用电离室作辐射剂量学的绝对测量，用胶片法进行相对测量，给出了测量结果并进行了讨论。     

丙烯酸接枝聚丙烯纤维的结构与性能

本文研究了用化学引发剂引发丙烯酸接枝聚丙烯纤维的某些影响因素。红外光谱分析表明，丙烯酸接枝在聚丙烯大分子链的叔碳原子上。Ｘ－射线衍射和ＤＳＣ分析指出，纤维接枝后结晶度有所增加，接枝前纤维存在的β－变体转化成了α－变体，接枝纤维的吸湿性、离子交换容量和染色性随接枝率增加而增大。接枝纤维的力学性能有所下降。     

空拉铜管“缩径”现象研究

揭示了空拉铜管时的“缩径”现象,分析了产生这种现象的原因以及各种工艺条件对其影响的规律。     

单液晶光阀彩色大屏幕投影显示

设计一电路,将彩色图象信息编码到黑白CRT的亮度之中,并将其写入液晶光阀,用白光读出,当编码合适时,读出的象颜色可与原图像一致。本文讨论了这一技术原理并进行了单液晶光阀彩色大屏幕投影的实验验证。     

Structural and gas-sensing properties of nanometre tin oxide prepared by PECVD

A low-temperature plasma-enhanced chemical vapour deposition (PECVD) technique has been employed to produce ultrafine tin oxide powders. The structural features and phase transition of this material have been characterized using differential thermal analysis (DTA), thermogravimetric analysis (TGA), X-ray diffraction, infrared spectroscopy (IR) and transmission electron microscopy (TEM). The oxygen absorption behaviour and gassensing properties have been investigated by electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS) and electrical measurements. Thick film gas sensors made from such ultrafine SnO₂ powders yield better sensitivities than those of normal undoped SnO₂ gas sensors. A gas-sensing reaction mechanism is also proposed.     

Multiresolution learning paradigm and signal prediction

Current neural network learning processes, regardless of the learning algorithm and preprocessing used, are sometimes inadequate for difficult problems. We present a new learning concept and paradigm for neural networks, called multiresolution learning, based on multiresolution analysis in wavelet theory. The multiresolution learning paradigm can significantly improve the generalization performance of neural networks     

Rejection of narrowband interference in DS spread spectrum systemsemploying minimum redundant nonlinear filters

A new nonlinear filter structure, the minimum redundant nonlinear filter (MRNF), for combating narrowband interference in direct sequence spread spectrum systems is proposed. Analytical expressions for the signal-to-noise ratio improvement factors are derived under the condition of single tone interference. The results show that the MRNF provides significantly better performance than the minimum redundant transversal filter     

High-speed Modulation of InGaAs: Sb-GaAs-GaAsP quantum-well vertical-cavity surface-emitting lasers with 1.27-/spl mu/m emission wavelength

1.27-/spl mu/m InGaAs: Sb-GaAs-GaAsP vertical-cavity surface-emitting lasers (VCSELs) were grown by metal-organic chemical vapor deposition and exhibited excellent performance and temperature stability. The threshold current changes from 1.8 to 1.1 mA and the slope efficiency falls less than /spl sim/35% as the temperature raised from room temperature to 70/spl deg/C. With a bias current of only 5 mA, the 3-dB modulation frequency response was measured to be 8.36 GHz, which is appropriate for 10-Gb/s operation. The maximal bandwidth is measured to be 10.7 GHz with modulation current efficiency factor (MCEF) of /spl sim/5.25 GHz/(mA)/sup 1/2/. These VCSELs also demonstrate high-speed modulation up to 10 Gb/s from 25/spl deg/C to 70/spl deg/C.     

连续运转的掺钛蓝宝石激光器

本文报导一种连续波氩离子激光泵浦的掺钛蓝宝石激光器。在氩离子激光功率(全谱线)为10.45瓦且仅用一组腔镜时,获得最大平均功率超过1000mW、调谐范围750～850nm的掺钛蓝宝石激光输出。