An action-chain model for the design of hazard-control systems forrobots

The authors establish a hazard-control design methodology based on a categorization of action changes and the dissociation of action chains. In this methodology, the damage process is modeled by propagation of actions among system elements, the actions are put into two groups (state-failure and function-failure), the concept of action-linkage dissociation is developed for damage prevention, application rules for information-processing systems are defined, and a systematic procedure to identify hazards and to conceptualize hazard-control systems is developed. It is postulated that dissociations involving paths or sources lead to fail-safe systems, while those involving substitution-of-function lead to fault-tolerant systems. Examples involving robot systems are given to demonstrate the new technology     

Flexible System LSI for Embedded Systems and Its Optimization Techniques

In this paper, we propose a chip architecture and design techniques to simultaneously reduce both the chip cost and power consumption of system-on-a-chip (SOCs). The chip cost of SOCs consists of the design cost, the mask cost, the fabrication cost, the package cost, and the test cost. In case that the production volume of one design is large, the fabrication cost becomes relatively larger than other costs. The minimization of the fabrication cost by shrinking the chip area has been the main problem to reduce the chip cost. SOCs are not always mass-produced and their design and the mask costs are dominant. We need new design criteria and a new design methodology for SOCs whose production volume is small. Our major contribution is a proposal of a design methodology based on new criteria suitable for SOC design. In our methodology, system designers use a pre-fabricated chip, called Flexible System LSI (FlexSys) chip, which consists of a processor, memories, and other cores specific to an application domain. At the fabrication phase, the power supply for unused parts of the FlexSys chip is cut off using a few additional masks which are designed for a specific application. This leads the reduction of wasteful power consumed by circuits which do not essentially contribute to the computation of the application. Since the basic die of the FlexSys is fabricated as a general purpose product, we can reduce the cost of the dies drastically. Experimental results show that about 30% power reduction can be achieved without performance loss by reducing the wasteful power consumption.     

斜入射液晶空间光调制器的特性

用读出光斜入射到液晶空间光调制器(LC-SLM)的读出面,是一种有效的提高空间光调制器(SLM)读出效率的方法。测量了读出光以不同角度入射到液晶空间光调制器的读出面上时,相位调制深度与写入光强的关系、衍射效率与二值光栅对比度的关系。得到随着入射角度的增加,最大相位调制深度减小,而衍射效率变化并不明显。在45°时有最大相位调制深度2.0936π和35.4%的正一级衍射效率。     

High-efficiency bipolar transconductors composed of hyperbolic function circuits with an intermediate voltage terminal and a triple-tail cell

Relatively high transconductance in bipolar devices contributes to the economy of power dissipation on analog integrated circuits. Recently, a high-speed transistor, such as the HBT attracts attention of researchers and developers in electronic communication industries and is expected to be applied to RF circuits. In this paper, high-efficiency bipolar transconductors are presented. The proposed circuits are composed of a hyperbolic function circuit with an intermediate voltage terminal and a triple-tail cell. The parameter values for linearisation are all integers. The values can be realised precisely. The linearity of the proposed transconductors is superior to the triple-tail cell. The linear input range is 1.5 times as wide as that of the conventional triple-tail cell. Nevertheless, the power dissipation is lower than the triple-tail cell. Further, sensitivity analysis shows that the proposed transconductors have lower sensitivity than the triple-tail cell. These properties are confirmed by SPICE simulation.     

Compact and low-loss arrayed waveguide grating module with tolerance-relaxed spot-size converter

A compact, low-loss arrayed waveguide grating (AWG) module was achieved by adopting a novel optical spot-size converter (SSC) to planar lightwave circuits (PLCs). The SSC is a laterally tapered waveguide that can be fabricated simply by the conventional fabrication process. The structure is composed of a core width converting region where the spot-size is converted efficiently, and a core width fine-tuning region where the cut-position tolerance is relaxed. We have applied this structure to a 1.5%-/spl Delta/ silica-based waveguides and reduced the single-mode fiber coupling loss to less than 0.5 dB/point. The SSC provides a large cut-position tolerance that enables angle polishing of the PLC endfaces to prevent reflection and low-loss connection of pigtail fibers. The center channel insertion loss of the AWG module was reduced from 4.2 to 2.2 dB, and the reflection was less than -60 dB.     

A 100-MHz 2-D discrete cosine transform core processor

A 100-MHz two-dimensional discrete cosine transform (DCT) core processor applicable to the real-time processing of HDTV signals is described. An excellent architecture utilizing a fast DCT algorithm and multiplier accumulators based on distributed arithmetic have contributed to reducing the hardware amount and to enhancing the speed performance. A layout scheme with a column-interleaved memory and a new ROM circuit are introduced for the efficient implementation of memory-based signal processing circuits. Furthermore, mean values of errors generated in the core were minimized to enhance the computational accuracy with the word-length constraints. Consequently, it features the fastest operating speed and the smallest area with sufficient accuracy to satisfy the specifications in CCITT recommendation H.261. The core integrates about 102 K transistors and occupies 21 mm² using 0.8-μm double-metal CMOS technology     

Wavelength conversion using a light injected DFB-LD and aMach-Zehnder filter with a ring resonator

Wavelength conversion using a light injected DFB-LD and a Mach-Zehnder filter with a ring resonator (r-MZ) is described. It utilizes frequency modulation of the DFB-LD induced by an external light and the FM/IM conversion function of the r-MZ filter. Owing to a unique characteristic of the r-MZ filter, the converter has good tolerance for input signal level and an effect of suppressing signal fluctuation, compared with a conversion scheme using a conventional MZ filter     

Variations in anatomy and ultraviolet microspectrometry between normal and brown midrib mutant maizes possessing different rumen degradabilities

Normal and brown midrib mutant (bmr) maize (Zea mays L) were examined for variations in their morphological composition. The degradability of the leaf blade, leaf sheath and stem, proportional area of specific tissues in leaf blade, and the ultraviolet (UV) absorption spectra of cell walls were measured and related to variations in cell wall degradability by rumen microorganisms. The UV and infrared (IR) absorption spectra of the lignins isolated from leaf blades of both types, before and after reduction with sodium borohydride, were recorded. The bmr3 maize had higher dry matter (DM) and neutral detergent fibre (NDF) degradabilities for leaf blade, leaf sheath, and stem than the normal counterpart. Approximately 35% and 26% of the observed difference in DM degradability was attributed to the difference in DM degradability of stem and leaf blade, respectively, and 39% to the difference in DM composition of stem. Distinct differences in tissue degradation of the leaf blades were observed for mesophyll cell walls in the midrib portion, which were thinner and of greater number in the bmr3 maize. Sclerenchyma cells were present only in the vascular bundles in the bmr3 leaf blade, while in the normal type those cells were underneath the epidermis tissue. The bmr3 plant also had large epidermal cells. UV microspectrometry of mesophyll cell walls of the bmr3 maize showed their lower UV absorbance around 320 nm compared to that of the normal, but not at 280 nm. Considerable increase in the UV absorbance at 280 nm was observed for the isolated lignins after reduction, suggesting a lesser degree of lignification in the bmr3 maize tissues. Lowered UV absorbance of the isolated lignin around 320 nm after reduction was associated with the removal of the IR bands at 1730, 1660, 1600, and 1250 cm^?1.     

A subnanosecond clock cryogenic system for Josephson computers

Using Josephson chips maintained at 4.4 K by a closed-cycle 3-W desk-size refrigerator, the authors verified the correct operation of a 4-b Josephson microprocessor up to 1.1 GHz. Room temperature and liquid He temperature regions are connected with a 130-ps delay using I/O cables passing through sidewalls of a vacuum vessel. It is proposed that both semiconductor and Josephson devices can coexist on circuit boards that constitute the equivalent of a single board