Analysis and Simulation of S-shaped Waveguide in Silicon-on-insulator

The simulation and analysis of S-shaped waveguide bend are presented.Bend radius larger than 30 mm assures less than 0.5 dB radiation loss for a 4-μm-wide silicon-on-insulator waveguide bend with 2-μm etch depth.Intersection angle greater than 20° provides negligible crosstalk (<-30 dB) and very low insertion loss.Any reduction in bend radius and intersection angle is at the cost of the degradation of characteristics of bent waveguide and intersecting waveguide, respectively.     

Experimental Research on Erbium-doped Superfluorescent Fiber Source

The effects of the variations in fiber length, fiber mirror reflectance on efficiency and output power are experimentally investigated for erbium-doped double pass backward superfluorescent fiber sources (SFSs). The influence of fiber length on mean wavelength stability (MWS) has also been demonstrated. By incorporating a short section of un-pumped erbium-doped fiber (EDF) at the output port, the pump power dependent on MWS becomes independent of pumped EDF length. This is a novel phenomenon that hasn‘t been reported up to now,and should be helpful to SFS fabrication and theory analysis. By using a fiber Michelson interferometer as spectrum slicing component,a multi-wavelength fiber source (MWFS) with ～20 channels (from 1542nm to 1559nm) is got. The MWFS has a channel spacing of ～0. 8 nm which satisfies ITUstandard. The intensity fluctuation among channels is less than 0.5dB,and the extinction ratio of all channels is above 14dB. This kind of MWFS should be useful to wavelength division multiplexing systems.     

会计政策选择的效率性分析

会计政策选择类型在理论上大体可分为机会主义型和效率(或有效契约)型。会计政策选择具有效率性,但也为经理人员的机会主义行为打开了大门。在我国,由于企业缺乏一系列有效的激励约束机制,会计政策选择的机会主义仍然严重。为此,必须建立适合我国企业有效的激励约束机制。     

油管电热清防蜡技术在强水敏油田的应用

江苏油田的庄 2、韦 2油田属强水敏油田 ,采用热 (水 )洗油井和化学清防蜡效果较差 ,两油田每年因洗井造成地层污染影响的产量损失在 5 0 0 0t以上 ,约占油田产量的 4 5 %。根据集肤效应 ,采用油管电热清蜡技术 ,在含水小于 6 0 %、井斜小于 4 0°的油井上可正常使用 ,一般通电加热 4 0～ 80min后 ,油井井口温度能达到 5 0℃左右 ,最高可达到 6 5℃以上 ,连续加热 5～ 6h即可达到清蜡目的 ,电热清蜡为周期 6 0～ 90d。影响电热清蜡主要指标因素是油井的产液量 ,产液量越小 ,所需要的加热电流和加热电压也越小 ,井口温度达到最高值越低 ,清蜡效果越差。试验的 7口井平均年度投入产出比达到 1∶5 ,经济效益和社会效益十分明显。     

Stem cells in prostatic epithelia

The normal prostate is, structurally and functionally, a highly complex glandular tissue in which populations of epithelial and stromal cells interact, one with the other, and are under a constant state of proliferation, differentiation, elimination and selective secondary replenishment so that functional integrity of the tissue is maintained. The ability of normal prostatic tissue to maintain its structure and function is dependent upon retention of cells, generally regarded as 'stem cells', which are able to respond by proliferation and selective differentiation within a wide range of phenotypic alternatives. With respect to cells in the epithelial compartment, replenishment is possible at several levels from within distinct pathways of normal cellular differentiation. It is now appreciated that fully differentiated prostatic epithelial cells retain a far greater degree of phenotypic 'plasticity' than was earlier apparent from morphological examination of the intact tissue. This inherent plasticity, coupled with the ability of the intact tissue to respond to diverse environmental (particularly humoral) stimuli by regenerating a wide and divergent spectrum of functional prostatic epithelial phenotypes is its strength--but also its weakness. Disturbance and distortion of the homeostatic regulatory mechanisms, whether physical or humoral, which control the normal sequence of epithelial proliferation, differentiation and elimination exposes these cells, particularly multipotent 'stem cells', to an increased probability of genetic change, thus resulting in either transient, or permanent, neoplastic transformation.     

Towards a generalized TLM algorithm for solving arbitraryreciprocal and nonreciprocal planar structures

A generalized transmission line matrix (TLM) algorithm is developed in the frequency domain to tackle arbitrary both reciprocal and nonreciprocal anisotropic waveguiding problems. In particular, the modeling issue for arbitrary planar structures is stressed in this work. A new three-dimensional (3-D) condensed node is used to consider the effect of both electric and magnetic constitutive tensors. Various results indicate how the modal dispersive behavior can be manipulated by changing not only the anisotropic characteristics of the substrate, but also the strip/slot geometry as well as the magnitude and orientation of the applied static magnetic field. The present algorithm is useful for CAD and simulation of a large class of gyrotropic waveguide-based microwave and millimeter-wave circuits     

直流电动机参数测定

根据直流电机的可逆原理并利用常规的实验仪表，可以简便、准确地测出直流电动机的主要参数－电磁转矩、输出转矩和效率．     

Tracking Control and Synchronization for Two-Dimension Discrete Chaotic Systems

1　ＩｎｔｒｏｄｕｃｔｉｏｎＳｉｎｃｅ 1 990 ,ｃｈａｏｔｉｃｓｙｎｃｈｒｏｎｉｚａｔｉｏｎ[1～ 4] ａｎｄｃｈａｏｔｉｃｃｏｎｔｒｏｌｌｉｎｇ[5～6] ｈａｖｅｒｅｃｅｉｖｅｄａｇｒｅａｔｄｅａｌｏｆａｔｔｅｎｔｉｏｎ[7～1 1 ] ,ａｎｄｃｈａｏｔｉｃｓｙｎｃｈｒｏｎｉｚａｔｉｏｎｉｓａｐｈｅｎｏｍｅｎｏｎｏｆｉｎｔｅｒｅｓｔｉｎｆｉｅｌｄｓｆｒｏｍｅｌｅｃｔｒｏｎｉｃｓｔｏｃｏｍｍｕｎｉｃａｔｉｏｎ[1 2 ] ,ａｎｄｆｒｏｍｂｉｏｐｈｙｓｉｃｓｔｏｎｅｕｒｏ ｓｃｉｅｎｃｅ[1 3] .Ｉｆｃｈａｏｔｉｃｓｙｎｃ…     

通用串行总线(USB)数据传输模型

USB作为一种数据传输接口，了解它的通信传输机制是正确利用USB利用数据传输的基础，分层次结构对USB数据传输模型加以分析，可以使读者建立起USB体系结构、通信模型和总线事务的框架和概念，并最终对USB传输工作流程有一个清晰的认识。     

HIPS-g-MA共聚物对HIPS/PC共混物相容性、形态和拉伸性能的影响

研究了HIPS／PC共混物的相容性及HIPS－MA对HIPS（30）／PC（70）共混物的相容性、形态和拉伸性能的影响。DSC研究结果表明，HIPS／PC共混物中PS的玻璃化转变温度（Tg)不随组成而变化，而PC的Tg随其质量分数的降低逐渐向低温移动，说明HIPS／PC是部分相容体系。通过DSC、扫描电镜形态观察和拉伸性能测试结果发现，当HIPS－g-MA的含量低于7．5％时，共混物的相容性改善不明显，当其含量达到7．5％时，对共混物有明显的乳化作用，说明饱和的界面浓度在7．5％左右。HIPS－g-MA接枝共聚物在HIPS（30）／PC（70）共混物中的增容作用可能是酯交换反应原位生成的嵌段共聚物所致。