Tuning characteristics of monolithic passively mode-lockeddistributed Bragg reflector semiconductor lasers

Tuning characteristics of multicontact passively mode-locked distributed Bragg reflector (DBR) semiconductor lasers are investigated in terms of center wavelengths and pulse repetition frequencies. It is shown that the center wavelength of the pulses can be tuned over a wide range by changing the refractive index of the Bragg reflector section either by means of carrier injection or by thermal effects while maintaining the pulses to be nearly transform-limited. Tuning of the pulse repetition rates is realized by using four different approaches, i.e., current injection to a passive phase-control section, varying of the reverse bias to the absorber, varying of the injection current to the gain region, and thermal effects. Injecting current into the phase-control region results in a tuning range of more than 400 MHz while maintaining the pulses at transform-limited condition. Varying the reverse bias voltage to the absorber is shown to be an alternative to achieve large repetition rate tuning, by which a tuning range of 600 MHz is obtained. By combining these tuning schemes, a total tuning range of more than 1 GHz is realized     

Nucleation, growth and retrogrowth of oxidation induced stacking faults in thin silicon-on-insulator

The nucleation, growth, and retrogrowth of stacking faults were investigated for thermally oxidized silicon-on-insulator substrates formed by the separation by implanted oxygen (SIMOX) method. It has been observed that for high oxidation temperatures (T >1150°C) oxidation induced stacking faults (OISFs) undergo a retrogrowth (shrinkage) process at noticeably lower temperatures than in bulk silicon. The retrogrowth process in thin film SIMOX substrates starts at approximately 1190°C for the 2 h thermal oxidations. In this paper, a model for the retrogrowth process is proposed based on the assumption that at high oxidation temperatures vacancies may be injected from the thermal oxide/top silicon interface. We suggest that the vacancy injection reduces the self-interstitial supersaturation and as a direct consequence, attenuates the OISF growth. We also propose that the self-interstitial supersaturation is reduced through point defect recombination inside the silicon overlayer and at the top-silicon/buried-oxide interface where a high density of steps and kink sites are found.     

Line Loss Minimization Control in a Loop Distribution System Using Circulating Current Compensation and Reactive Current Suppression by a Unified Power Flow Controller

This paper describes line loss minimization control using the shunt and series converters of a UPFC (unified power flow controller) in a loop distribution system. The line losses in a loop distribution system are caused by the circulating current flowing in the loop and the mesh currents flowing to the loads. The authors have previously proposed a compensation method for circulating current using a series converter. In this paper, the authors propose a suppression method for reactive currents using a shunt converter. In the prototype model of a loop distribution system, a theoretical loss reduction ratio of 92% without line loss caused by active currents is obtained. Similar line loss reduction characteristics are obtained in experiments using the prototype distribution system.     

Fast collision detection between complex solids using rasterizing graphics hardware

We present an efficient method for detecting collisions between complex solid objects. The method features a stable processing time and low sensitivity to the complexity of contact between objects. The algorithm handles both concave and convex objects; however, the best performance is achieved when at least one object is convex in the proximity of the collision zone (our techniques check the required convexity property as a byproduct of the calculations). The method achieves real-time performance when calculations are supported by the standard functionality of graphics hardware available on high-end workstations.     

Postoperative chemotherapy including intraperitoneal and intradermal administration of the streptococcal preparation OK-432 for patients with gastric cancer and peritoneal dissemination: a prospective randomized study

We studied the effects on survival time of postoperative immuno-chemotherapy, including the streptococcal preparation OK-432, in patients with gastric cancer and synchronous peritoneal dissemination. The patients were prospectively randomized and a valid statistical assessment could be made for 109. Patients randomized to group B received therapy that is widely used in Japan to treat patients with gastric cancer: mitomycin C (MMC) and UFT, a combination of tegafur and uracil in a molar ratio of 1:4, for 1 year. Patients randomized to group A received the same drugs as were given to group B patients plus OK-432 i.p. for 7 days, beginning on postoperative day 0, and OK-432 by intradermal injection for 1 year, at 2-week intervals. There were no differences between the two groups in any known prognostic factor or in the dose of any drug administered except for OK-432. There was no difference in the toxicity rate between the groups. In this negative trial, there was no improvement in survival time with the addition of OK-432 to MMC and UFT for patients with gastric cancer and peritoneal dissemination.     

Function Representation of Solids Reconstructed from Scattered Surface Points and Contours

This paper presents a novel approach to the reconstruction of geometric models and surfaces from given sets of points using volume splines. It results in the representation of a solid by the inequality f(x,y,z) ≥ 0. The volume spline is based on use of the Green's function for interpolation of scalar function values of a chosen “carrier” solid. Our algorithm is capable of generating highly concave and branching objects automatically. The particular case where the surface is reconstructed from cross-sections is discussed too. Potential applications of this algorithm are in tomography, image processing, animation and CAD for bodies with complex surfaces.     

Narrow energy distribution of output electrons from a modified single channel electron multiplier

New methods which reduce the unfavorable energy spread of output electrons from a single channel electron multiplier are presented. A modified output electrode produces a pronounced narrowing effect on the energy distribution without much affect on the gain. A simplified analysis of the field inside the channel shows that the fixed channel wall potential near the output end is responsible for the narrow energy distributions obtainable.     

CrossoverNet: A computer graphics/ video crossover LAN system

A new type of local area network operating system namedCrossover Net is developed for effective control of digital devices and audio visual devices such as video cameras, TV displays, video discs and video cassette recorders. A remarkable feature ofCrossoverNet is that it can handle and transfer both digital and analog information, including data, video and voice, in an integrated manner. To ensure secure operations of the entire network, we formalizeCrossoverNet in a precise mathematical way by defining object, job, task and process as data types belonging toCrossoverNet. We also present a practical installation example of theCrossoverNet system.