Picosecond semiconductor laser radar with optical amplifier

An optical range finder, which uses the same semiconductor laser as both an optical pulse source and an optical preamplifier of the reflected pulse, is reported. This method has the advantage of reducing the number of optical components that must be aligned, which makes it suitable as a picosecond laser radar in aerospace applications. The device showed a maximum optical gain of 17 dB with a dynamic range of 33 dB, and the obtained resolution was of the order of 1 mm.     

RPTS中的并行与可视化技术

研制了一个进化型快速原型工具系统ＲＰＴＳ，提出了伪函数技术和分割图技术。前者使应用系统的界面原型和内部功能原型的开发工作完全并行化，后者提高了内部功能描述的可视化程度。详细讨论了伪函数、分割图及相关算法。     

Molecular genetic diagnosis of von Hippel-Lindau disease in familial phaeochromocytoma

Inherited predisposition to phaeochromocytoma is seen in multiple endocrine neoplasia type 2 syndromes, von Hippel-Lindau (VHL) disease, and neuro-fibromatosis type 1. In addition familial phaeochromocytoma alone has been reported. To investigate the genetic basis for familial phaeochromocytoma alone, we screened three affected kindreds for mutations in the RET proto-oncogene and the VHL tumour suppressor gene. We did not detect MEN 2 associated RET mutations in any family, but missense VHL gene mutations (V155L and R238W) were identified in two kindreds with no clinical evidence of VHL disease. Patients with familial, multiple, or early onset phaeochromocytoma should be investigated for germline VHL and RET gene mutations as the molecular diagnosis of multisystem familial cancer syndromes enables appropriate counselling and screening to be provided.     

用于结构光分布图采集的图像帧存贮器设计

设计了一种用于结构光分布图采集的图像帧存贮器（ＲＡＭ）电路。由于预先对结构光分布进行了硬件细化处理以及大容量存贮芯片的使用，电路设计十分简单。该系统带可作为数字化仪用于各种二值图像的数字化，并可作为计算机和其它外设的输入／输出缓冲设备。     

Geometric foundations for surface-generating machining: Tool calculations and computer generation of the surface

The main content of this paper is a new general method for cutting tool calculations. The general method takes into account all known specific cases and can also be used for any new machining methods not known hitherto. In order to derive relationships between the shape of the workpiece surface to be machined and the shape of the cutting tool working surface, the theory of contact surfaces has been used employing matrix calculus. Matrix calculus uses a short and clear algorithm which is especially useful while using computers. The paper demonstrates the way to work out difficult, spatial problems using the generation method. The paper will be very useful for tool designers and researchers.     

1H nuclear magnetic resonance characterization of Portland cement: molecular diffusion of water studied by spin relaxation and relaxation time-weighted imaging

Water molecular dynamics in a hardened Portland cement were characterized by proton Fourier transform nuclear magnetic resonance (NMR) at 400 MHz. Three different types of water molecule (physically bound, chemically bound and porous trapped) were observed. When the hardened cement sample was heated at 105 °C, the physically bound water diffused out of the sample as a function of the heating time while the chemically bound water remained in a stable form. A trace amount of the porously trapped water was also detected to remain in the cavities of the hardened cement even after heating for up to 20 h at this temperature. The loss of the physically bound water proved to be a diffusion-controlled process as evidenced from the NMR data and from a gravimetric technique. A Pake doublet was observed in the NMR spectra. This is a result of the oscillation of the water molecules with hindered molecular motions due to their entrapment in the cement pores. Soaking the dried samples in water resulted in the diffusion of water back into the hardened cement as physically bound water. Nuclear spin–spin relaxation time, T2-weighted imaging showed that the distribution of the physically bound water inside the cylindrical sample formed a doughnut shape after overnight soaking. The residual air in the cement pores may have slowed down the diffusion rate of the water molecules back into the dried cement. © 1998 Kluwer Academic Publishers     

Polymernetzwerke zum Einschluß von Mikroorganismen

Different network formation processes, applicable to obtain biocatalytic systems by entrapment of whole microbial cells are described. Properly chosen suspension techniques can be used to prepare copolymer beads from water soluble or water insoluble monovinyl divinylmonomer systems. Inclusion of small NaCI crystallites during the curing process leads to epoxy resins which possess a macroporous as well as a highly microporous structure. Crosslinking of natural, seminatural and synthetic polyelectrolytes with multivalent cations (?ionotropic gels”?) proves to be a very gentle entrapment procedure. Networks of nonspecific bonding character are obtained by precipitation of linear water insoluble or poorly water-soluble polymers.     

8 Gbit/s optical transmission with t.j.s. GaAlAs laser and p-i-n detection

Optical transmission at 8 Gbit/s has been performed with a t.j.s. laser and a low-impedance microstripline-mounted p-i-n diode. The laser was modulated with 100 ps wide pulses and no intersymbol interference was observed.