A Configurable Enhanced TTRAM Macro for System-Level Power Management Unified Memory

A twin-transistor random access memory (TTRAM) can provide high speed, low power and high density with CMOS compatible SOI process. However it is difficult to handle as the unified memory required for advanced SoC because it needs the simple control sensing operation for memory compiler, higher cell efficiency, and lower voltage operation for dynamic frequency and voltage control. Enhanced TTRAM (ET²RAM) applies the actively body-bias control technique to realize the low voltage array operation, and never require the negative voltage source. The ET2RAM can realize both 263 MHz at 0.8 V and 10.2 mW at 0.5 V random-cycle operation, higher cell efficiency, and process scalability. It also provides the simple control method suitable for the unified macro for system-level power management SoC with keeping the merits of TTRAM as CMOS compatibility     

Dependence of Seebeck coefficient on a load resistance and energy conversion efficiency in a thermoelectric composite

The thermo-emf ΔV and current ΔI generated by imposing the alternating temperature gradients (ATG) at a period of T and the steady temperature gradient (STG) on a thermoelectric (TE) composite were measured as a function of t, where t is the lapsed time and T was varied from 60 to or ∞ s. The STG and ATG were produced by imposing steadily and alternatively a source voltage V in the range from 1.0 to 4.0 V on two Peltier modules sandwiching a composite. ΔT, ΔV, ΔI and V_P oscillate at a period T and their waveforms vary significantly with a change of T, where ΔV and V_P are the voltage drops in a load resistance R_L and in resistance R_P of two modules. The resultant Seebeck coefficient |α| = |ΔV|/ΔT of a composite under the STG was found to be expressed as |α| = |α₀|(1 − R_comp/R_T), where R_T is the total resistance of a circuit for measuring the output signals and R_comp is the resistance of a composite. The effective generating power ΔW_eff has a local maximum at T = 960 s for the p-type composite and at T = 480 s for the n-type one. The maximum energy conversion efficiency η of the p- and n-type composites under the ATG produced by imposing a voltage of 4.0 V at an optimum period were 0.22 and 0.23% at ΔT_eff = 50 K, respectively, which are 42 and 43% higher than those at ΔT = 42 K under the STG. These maximum η for a TE composite sandwiched between two Peltier modules, were found to be expressed theoretically in terms of R_P, R_T, R_L, α_P and α, where α_P and α are the resultant Seebeck coefficients of Peltier modules and a TE composite.     

Retardation‐controlling color filter with two directly stacked retardation layers

Abstract— A polymerizable liquid crystal (PLC), the orientation of which can be frozen, is useful for making retardation layers. In this paper, a new color filter (CF) with retardation‐controlling layers made of PLC is reported. It has a positive A‐plate and a negative C‐plate, both directly stacked on a color‐filter layer. These two retardation layers exhibit good orientation ability, and function well as retarders, even when they are only 1/10 or less as thick as ordinary retardation films. The new CF also has excellent thermal stability. The change in retardation after heat treatment at 200°C for 30 min is around 5%, and there is no observable peeling. A prototype VA‐LCD made with our new CF provides good optical compensation, with the light leakage being extremely low in all azimuthal directions. This technology is very useful for making thin, highly reliable color filters for LCDs, even with other modes.     

Land surface phenology dynamics and climate variations in the North East China Transect (NECT), 1982–2000

Land surface phenology dynamics reflect the response of the Earth's biosphere to inter‐ and intra‐annual dynamics of the Earth's climate and hydrologic regimes. Investigations of land surface phenology dynamics and its relation to long‐term climate variation could help us to detect the response of regional vegetation to climate variation. The present study developed a new algorithm for detecting regional land surface phenology dynamics (ARLSPD) and demonstrated it in detecting the vegetation response to inter‐annual climate variability in the North East China Transect (NECT), a mid‐latitude semi‐arid terrestrial transect with strong gradients in environmental conditions and vegetation formations. The spatial–temporal patterns of greenup‐onset date, maturity date, and senescence date during the period of 1982–2000 are presented. The resultant spatial–temporal patterns of land surface phenology were quite consistent with the land‐cover characteristics, moisture, and temperature gradients. The relations between inter‐annual variations in phenology and seasonal climate were investigated. It was found that besides human disturbance, land surface phenology depended primarily on the combined effects of preseason temperature and precipitation. The relative influence of preseason temperature and precipitation on land surface phenology was changing, which led to the different responses of land surface dynamics to climate variation along the moisture gradient in the NECT. In the arid and semi‐arid region of NECT, the dates of onset for phonological events in temperate typical grassland were most significantly related to the precipitation during the preceding 2–4 months. Temperature‐induced drought stress during the preceding months could delay greenup onset in cropland/grassland mosaic, and advance senescence in temporal typical grassland, and in cropland/grassland mosaic. The regional phenology algorithm, theoretically also applicable for complex ecosystems characterized by annual multiple growth cycles, is expected to couple with large‐scale biogeochemical models to regulate dynamically land surface phenology.     

Continuous synthesis of Zn2SiO4:Mn fine particles in supercritical water at temperatures of 400-500 °C and pressures of 30-35 MPa

Sub-micron sized Zn₂SiO₄:Mn²⁺ phosphors particles were continuously synthesized in supercritical water with a flow reactor. Colloidal silica or sodium silicate was used as the Si source. Zn and Mn sources were chosen from their nitrates, sulfates, and acetates. The syntheses were carried out at temperatures from 400 to 500 °C, at pressures from 30 to 35 MPa, at NaOH concentrations from 0.014 to 0.025 M, and for residence times from 0.025 to 0.18 s. Sodium silicate formed α- and β-Zn₂SiO₄:Mn²⁺ phases regardless of the Zn and Mn sources, while colloidal silica formed phases dependent on the type of Zn and Mn sources used in addition to the use of alkali. As the reaction temperature increased, the crystallinity of α-Zn₂SiO₄:Mn²⁺ phase increased and the Mn substitution into the Zn sites of the α-Zn₂SiO₄ phase decreased. Of the conditions studied, the most highly crystalline α-Zn₂SiO₄:Mn²⁺ was produced at a temperature of 400 °C, a pressure of 30 MPa, a NaOH concentration of 0.14 M, and a residence time of 0.13 s with Zn and Mn sulfates and colloidal silica as starting materials. The α-Zn₂SiO₄:Mn²⁺ fine particles synthesized were round in shape, had an average diameter of 268 nm, and exhibited a green-emission with a peak wavelength of 524 nm.     

Incorporation of Dust Particles into a Growing Film During Silicon Dioxide Deposition from a TEOS/O2 Plasma

The effects of gas flow rate on particle formation and film deposition during the preparation of silica thin film using a TEOS/O₂ plasma were investigated. Particle formation and growth are suppressed with increasing gas flow rates. The film deposition rate increases with increasing gas flow rate, reaches a maximum value, and eventually decreases again. However, the uniformity of the film tends to degrade at high gas flow rates. At a high gas flow rate, some particles trapped in the sheath near the grounded electrode pass through the sheath to reach the substrate and are then embedded in the growing film. A self-consistent sheath model combined with particle force balance based on charge fluctuation was developed to explain these experimental findings qualitatively. The model reveals that charge fluctuation is a key factor for the particle to overcome the potential barrier of the negatively charged particles to pass through the sheath, eventually reaching the substrate. The model further shows that the probability of a particle being deposited on the substrate is higher for increased gas flow rates, which correctly predicts the experimentally observed trend.     

Highly photostable distributed-feedback polymer waveguide blue laser using spirobifluorene derivatives

In this study, we synthesized the new spirobifluorene derivatives; hexylbiphenyl-spirobifluorene (HBP-Spiro) and triphenylamine-spirobifluorene (TPA-Spiro) and demonstrated the operation of a distributed-feedback polymer waveguide blue laser. In addition, we investigated the optical and lasing properties of spirobifluorene derivatives including photostability. The experimental slope efficiency and the energy threshold of a HBP-Spiro-doped waveguide laser were 3.6% and 1.9 μJ, respectively. An operation lifetime of 27,000 shots was obtained for a pump-pulse duration of 1.2 ns and energy of 3.0 μJ at a wavelength of 355 nm.     

Radiation distribution sensing with normal optical fiber

The purpose of this study is to develop a radiation distribution monitor using a normal plastic optical fiber. The monitor has a long operating length and can obtain continuous radiation distributions. A principle of the position sensing is based on a time-of-flight technique. The monitor is sensitive to beta rays or charged particles, gamma rays, and fast neutrons. The spatial resolutions for beta-rays ( ⁹⁰Sr-⁹⁰Y), gamma-rays (¹³⁷Cs), and D-T neutrons are 30, 37, and 13 cm, respectively. The detection efficiencies for the beta-rays, gamma-rays, and D-T neutrons are 0.11%, 1.6×10 ^-5% and 1.2×10^-4%, respectively. The effective attenuation length of the detection efficiency is 18 m. In this paper, we describe the basic characteristics of this monitor     

Fast Labelling of Natural Scenes Using Enhanced Knowledge

A new technique for labelling natural scenes is proposed. This technique labels disjoint regions on an image of a natural scene on the basis of knowledge about the relationship among objects. The proposed technique consists of three stages: (1) segmentation, (2) initial labelling, and (3) label improvement. One of the most promising previous techniques uses simulated annealing to find the solution, while our technique uses local hill-climbing with enhanced knowledge for speeding up the processing. Local hill-climbing is known to be easy to be captured by a local minimum. We solved this problem by enhancing the knowledge being used as constraints for the search. Our knowledge represents 1-to-n relationships among regions, pair-wise relationships of regions, and relative locations of the regions to the image. In addition, we introduced two region features: an entropy in intensity; and a linearity of contours of each region. The linearity evaluation aims to distinguish artificial objects from natural objects. The validity of the technique is supported by some experiments. These experiments showed that the proposed technique is much faster with the almost same accurate.     

Solution properties of polymacromonomers consisting of polystyrene

Summary Dynamic light scattering measurements have been made on 14 samples of a polymacromonomer consisting of polystyrene with 15 styrene side-chain units in cyclohexane at 34.5°C (the theta point) to determine the translational diffusion coefficient D as a function of molecular weight. The dependence of D on the main-chain length is analyzed on the basis of the wormlike chain by taking into account the end effect arising from side chains near the main-chain ends. The model parameters describing this dependence, i.e., the Kuhn segment length (11.5 ± 1.5 nm), the linear mass density (5600 ± 700 nm⁻¹), the diameter (5.2 ± 0.5 nm), and the end-effect parameter δ (2.5 ± 0.3 nm), are close to those determined previously from <S ²>_z (the z-average mean-square radius of gyration) and [η] (the intrinsic viscosity), leading to the conclusion that the wormlike chain model is capable of consistently explaining <S ²>_z, [η], and D of the polymacromonomer in the Θ solvent. Received: 8 February 2000/Accepted: 18 February 2000