A multilevel soliton communication system

A multilevel soliton communication system is proposed and assessed. In this system, at the transmitter end each channel transmits its data via fundamental solitons with a pre-specified amplitude (i.e., soliton width). At the receiver end we take advantage of the sensitive relationship between the amount or fundamental soliton self-wavelength shift and the width of the soliton in the subpicosecond region. We first compress the incoming soliton noises to the subpicosecond level and pass them through a short length of fiber at the end of which the pulses have become separated in the wavelength domain since each soliton, corresponding to a data channel, has experienced a different Raman self-wavelength shift. The channels are then easily separated by optical filters. We have derived the design constraint relations for such a system. We have then heuristically designed a 40 Gbs (four channels) system for a 1000 km propagation distance (total data-rate distance product of 40 Tb/km). Numerical simulations and noise analyses have verified the feasibility and practicality of the proposed system with very good design margins. The wavelength jitter is found to be much smaller than the desired filter spacing, and thus its contribution to the bit error rate is negligible. We also argue that the system is more tolerant to Gordon-Haus timing jitter than conventional TDM soliton systems. The system is all fiber and is, therefore very cost effective as it does not require sophisticated electro-optic and microwave circuits for demultiplexing. The system can potentially operate at much higher speeds than those achievable in conventional soliton systems and it can be used in parallel with WDM soliton system     

传输线衰减常数与柱形谐振器Q值的关系

文中严格地讨论了任意截面形状，任意模式的柱形谐振腔Ｑ值与构成该谐振器的传输线衰减常数间的关系，给出了更一般的公式，推广了Ｄａｖｉｄｓｏｎ和Ｓｉｍ－ｍｏｎｄｓ＾［１］、Ｂａｒｌｏｗ和Ｃｕｌｌｅｎ＾［２］以及Ｙｅｈ和Ｓｈｉｍａｂｕｋｕｒｏ＾［３，４］的结果。     

Growth And Industrial Organisation

The bicycle industry is an interesting case where East Asian firms have made a considerable impact, but where Taiwan has outperformed Korea. In the Korean sector, none of the well-known chaebol such as Samsung have become involved, and the incumbent firms experienced slow growth until there was government intervention in the 1980s. In Taiwan, small dynamic firms responded to large export orders in the early 1970s, and established a lasting lead which has been regenerated through technological upgrading. The paper argues that both countries’ bicycle industries have a vertically non-integrated structure, with extensive internal sub-contracting, and that the differences between the countries can be attributed to the timing and effcacy of industrial policy interventions.     

Endothelin-1 concentrations and optimisation of arterial oxygenation and venous admixture by selective pulmonary artery infusion of prostaglandin E1 during thoracotomy

PURPOSE: To demonstrate a superselective intraarterial chemotherapy as a therapeutic alternative in the treatment of previously treated recurrent lymph node metastases in breast cancer. METHODS: 14 patients with recurrent lymph node metastases in cases of breast cancer were presented to be treated by intraarterial chemotherapy of 25 mg mitoxantrone/m2 over a period of 24 hours. In two patients with superclavicular lymph node involvement an intraarterial therapy could not be carried out because of a vascular connection to the anterior spinal artery. Involved lymph stations could be reached in superselective technique by side branches of the subclavian artery. Heparin coverage was given intravenously. Every patient had had surgery, radiation, systemic chemo- and hormonal therapy before and was now graded as inoperable. Therapy indication was given by local tumour-induced symptoms. RESULTS: In the 12 treated cases complete remission was seen in three, partial remission in 4, a steady state in two and a progressive disease in three. There were no complications or severe side effects. CONCLUSION: Intraarterial chemotherapy is an effective and well tolerated treatment in recurrent lymph node metastases in cases of breast cancer even if conventional therapies can no longer be used.     

淀积条件对GDa—SiNx薄膜电学特性的影响

本文讨论了用辉光放电法制备氮化硅薄膜时衬底温度、射频功率和气体流量比对薄膜的电导率、介电常数和击穿强度的影响。通过优化生长条件，制备了优质非晶氮化硅薄膜，其介电常数为７．５、击穿强度为５．５ＭＶ／ｃｍ、电导率为１０－１３（Ωｃｍ）－１。     

极尖断面为折线的四极透镜磁性能研究

对传统双曲线极尖的四极透镜进行了磁性能分析。在此基础上，提出了极尖断面为折线的四极透镜结构。磁场的数值分析以及测量结果表明：该结构产生的场梯度均匀，且具有磁场集中、磁场梯度高、便于加工和安装的对称性控制等优点。该结构的四极透镜已用于ＣＹＣＩＡＥ－３０回旋加速器和ＨＩ－１３串列加速器束流输运线之中     

Effects of substrate temperature and texturing on the magnetic properties and crystallographic structures of CoCrTa/Cr thin film

Bi-layer CoCrTa/Cr films were deposited on textured aluminium or textured NiP-plated aluminium substrate by d.c. magnetron sputtering. The crystal anisotropy and thereby magnetic properties depending on substrate material, substrate temperature and texturing, were investigated. The magnetic crystal anisotropy induced by the mechanical texture on aluminium or NiP/Al substrates along the texture lines for the film deposited at high temperature, were clearly observed, while the film deposited at low temperature shows less prominent anisotropic behaviour. X-ray diffraction analysis indicates a change in the preferred orientation of the chromium and CoCrTa films sputtered on different substrates at different temperatures. It was found that a high substrate temperature was beneficial to the formation of Cr(002) and therefore epitaxial growth of Co(11¯20) on Cr(002) for either aluminium or NiP/Al substrates.     

Temperature Dependence of Ultra-Low-Frequency Dielectric Relaxation of Barium Titanate Ceramic

Based on a linear voltage ramp method, ultraslow dielectric relaxation of undoped BaTiO₃ ceramic has been carefully measured over the temperature range between − 180° and +120°C. Temperature dependence of the dielectric constant in the frequency range from 10 ⁻⁵ to 10⁻¹ Hz can be obtained using Kramers–Kronig equations. Close to the Curie temperature, the dielectric constant increases so rapidly that the Curie peak is overwhelmed. Two kinds of relaxation processes were observed in this experiment. Ferroelectric domain and mobile charge are proposed to be responsible for the relaxation over the temperature range. With temperature increasing, Maxwell–Wagner relaxation associated with mobile charge gradually dominates. From relaxation time constants at various temperatures, relaxation activation energies about 0.06 and 0.09 eV are identified.     

Magnetism in SiC implanted with high doses of Fe and Mn

High concentrations (0.1–5 at.%) of Mn or Fe were introduced into the near-surface region (≤2000 Å) of 6H-SiC substrates by direct implantation at ～300°C. After annealing at temperatures up to 1000°C, the structural properties were examined by transmission electron microscopy (TEM) and selected-area diffraction pattern (SADP) analysis. The magnetic properties were examined by SQUID magnetometry. While the Mn-implanted samples were paramagnetic over the entire dose range investigated, the Fe-implanted material displayed a ferromagnetic contribution present at <175 K for the highest dose conditions. No secondary phases were detected, at least not to the sensitivity of TEM or SADP.