Process development on the monolithic fabrication of an ultra-compact 4×4 optical switch matrix on InP/InGaAsP material

We have fabricated an ultra-compact 4×4 optical matrix on InP/InGaAsP material. 1×4 MMI couplers and TIR mirrors are employed to produce a compact 1×2 mm2 device. A CH4/H2/O2 RIE dry etch process has been used to realize two-level dry etching: deep-etch for both the MMI couplers and the mirrors and shallow-etch for the rest of the routing waveguides. It was found that a metal/dielectric bilayer mask is essential for multi-dry-etch processes and high profile verticality. We have found a Ti intermediate mask for the deep-etch process which is removable by SF6 dry-etch before the following shallow process. Dry-etch removal of the intermediate mask is necessary to protect the deep-etched mirror sidewall.

Influence of voltage and frequency dimming on power losses in HF electronic ballasts for compact fluorescent lamps

Compact Fluorescent Lamps (CFL) incorporating electronic ballasts are widely used in lighting. In many cases the ability to dim the lamp is a requirement Dimming can be achieved by varying the voltage supplied to the inverter or by changing the switching frequency of the inverter. The effect of dimming by both approaches on the power losses in the inverter is studied in this work. The lamp and associated inverter has been modeled in PSPICE, using a behavioral model for the CFL. Predicted losses are in good agreement with experimental data obtained from calorimetry. The model was then used to determine the distribution of losses within the inverter, enabling a comparison of the effects of the two dimming methods to be made. © 2006 IEEE.

A normal force distance regulation scheme for near-field optical microscopy

A near-field optical microscope (NFOM) has been developed that combines the features of a near-field optical microscope and an atomic force microscope. Improved control over tip-sample separation has led to improved optical imaging and independent surface topography information. The tip oscillation is normal to the sample plane thereby reducing lateral forces - important for nonperturbative imaging of soft samples. Both topographic images and reflection near-field optical images are presented which demonstrate the capability of the system. © 1996 American Institute of Physics.

High-quality pulse compressor for WDM/OTDM applications

The paper reports the results of a high-quality pulse source incorporating a gain-switched laser diode followed by a novel compact two-cascade fibre compression scheme. The pulse compression scheme incorporates a dispersive delay line and a nonlinear pulse compressor based on a dispersion-imbalanced fibre loop mirror (DILM). We analyse and demonstrate for the first time significant improvement of the loop performance by means of the chirped pulse switching. As a result, the DILM provides high-quality nonlinear pulse compression as well as rejection of the nonsoliton component. In the experiment, 20ps pulses from a gain switched laser diode are compressed to a duration of 300fs at a repetition rate in range 70MHz-10GHz. The pulses are pedestal free and transform-limited. Spectral filtering of the output signal by means of a bandpass filter results in generation of wavelength-tuneable picosecond pulses with a duration defined by the filter bandwidth. Alternatively, signal filtering by an arrayed waveguide grating (AWG) results in multichannel picosecond pulse generation for WDM and OTDM applications. The pulse source is built of standard components and is of compact and potentially robust design.

Losses in inductor-less piezoelectric transformer ballast for compact fluorescent lamps

In this study an inductor-less piezoelectric transformer (PT) based ballast for a 5 W CFL has been designed and simulated. The predictions of circuit currents and losses closely match experimentally measured values. The total simulated loss figure was confirmed against practically determined losses using a precision mini-calorimeter. Using simulation to disaggregate the total loss figure, it is seen that the PT makes the largest contribution to the total losses in such ballast.

Fast and compact simulation models for a variety of FET nano devices by the CMOS EKV equations

In this paper we explore the possibility of using the equations of a well known compact model for CMOS transistors as a parameterized compact model for a variety of FET based nano-technology devices. This can turn out to be a practical preliminary solution for system level architectural researchers, who could simulate behaviourally large scale systems, while more physically based models become available for each new device. We have used a four parameter version of the EKV model equations and verified that fitting errors are similar to those when using them for standard CMOS FET transistors. The model has been used for fitting measured data from three types of FET nano-technology devices obeying different physics, for different fabrication steps, and under different programming conditions. © 2009 IEEE NANO Organizers.

Losses in self-oscillating ballasts for electrode-type compact fluorescent lamps

Commercially available integrated compact fluorescent lamps (CFLs) use self-resonant ballasts on grounds of simplicity and cost. To understand how to improve ballast efficiency, it is necessary to quantify the losses. The losses occurring in these ballasts have been directly measured using a precision mini-calorimeter. In addition, a Pspice model has been used to simulate the performance of an 18 W integrated CFL. The lamp has been represented by a behavioural model and Jiles-Atherton equations were used to model the current transformer core. The total loss is in close agreement with measurements from the mini-calorimeter, confirming the accuracy of the model. The total loss was then disaggregated into component losses by simulation, showing that the output inductor is the primary source of loss, followed by the inverter switches. © 2011 The Institution of Engineering and Technology.

The intraspecific difference of the triose phosphate isomerase ( tim) gene from Giardia lamblia

目的　探讨蓝氏贾第鞭毛虫 (Giardialamblia)磷酸丙糖异构酶基因种内差异。方法　提取虫体总DNA ,对所有虫株磷酸丙糖异构酶 (tim)基因部分片段进行PCR扩增。测定序列后 ,用简约法和NJ法构建系统树进行系统发育分析。结果　共有 12 4个位点存在变异 (占所有测定序列中的 2 3% ) ,且大多数为发生在密码子的同义突变。两种构树方法所得二树的分枝结构相似 ,均将受试的 16株蓝氏贾第虫分为明显的两组。结论　宿主及地理因素对蓝氏贾第虫群体的遗传多样性影响不大。在DNA分子进化水平上 ,自然选择的影响十分显著。可将tim基因作为蓝氏贾第虫群体遗传结构一个十分有效的遗传标记。

Preliminary chemical and physical evaluation of some formulated feeds for P. monodon

The culture of Penaeus monodon has explicitly defined the need for diet formulations or supplementary feeds that would promote optimum growth and survival of the animal. A total of 28 feed combinations were developed for P. monodon. Fish meal, shrimp head meal, squid head meal, Ascetes spp. rice bran, and soybean cake were used as primary ingredients in these feeds. The commercial vitamin mix No. 22 was added to the dry ingredients. Gelatinized corn starch and wheat flour were used as binders. The pellets were extruded using a portable kitchen grinder with a diameter of 4 mm. The products were either sun-dried for 8 hours or oven-dried overnight at 50 degree C to stabilize moisture at 8-10%. The pellets were then kept in covered glass bottles and stored in the laboratory at room temperature. The cost of the feeds excluding labour were also computed. The pellets were analyzed for protein, fat, carbohydrate, crude fiber, ash, and moisture contents using standard procedures. They were also analyzed for water stability. To test the stability of pellets in water, 2-g samples were placed in plankton nets (mesh #40) and suspended in water for two, and six hours. The undissolved samples were then vacuum-dried and the moisture determined. Cost of the feeds ranged from P1.10 to P2.60 per kg depending on the feed ingredient. Squid and Ascetes spp. were rather expensive for use as basic ingredients. Proximate analysis of dry weight showed percentage protein content ranged from 20-63 g; fat, 8-20 g; carbohydrate (by difference), 11-36 g; ash, 8-28 g; moisture, 6-11 g; and crude fiber, 5 . 13 g. Stability tests showed that after two hours, 35-88% of solids remained intact and after 6 hours, 20-55% of the pellets remained undissolved. When a pellet disintegrates easily, pollution of the water occurs. Chances for the shrimp to feed on the pellet is minimized when the pellet is unstable. Thus, the search for a more compact feed pellet has to be continued.