Advanced TFT SRAM cell technology using a phase-shift lithography

An advanced TFT memory cell technology has been developed for making high-density and high-speed SRAM cells. The cell is fabricated using a phase-shift lithography that enables patterns with spaces of less than 0.25 μm to be made using the conventional stepper. Cell area is also reduced by using a small cell-ratio and a parallel layout for the transistor. Despite the small cell-ratio, stable operation is assured by using advanced polysilicon PMOS TFT's for load devices. The effect of the Si₃N₄ multilayer gate insulator on the on-current and the influence of the channel implantation are also investigated. To obtain stable operation and extremely low stand-by power dissipation, a self-aligned offset structure for the polysilicon PMOS TFT is proposed and demonstrated. A leakage current of only 2 fA/cell and an on-/off-current ratio of 4.6×10⁶ are achieved with this polysilicon PMOS TFT in a memory cell, which is demonstrated in a experimental 1-Mbit CMOS SRAM chip that has an access time of only 7 ns     

Accuracy assessment of a noninvasive device for monitoring beat-by-beat blood pressure in the radial artery using the volume-compensation method

For the noninvasive and accurate measurement of instantaneous blood pressure (BP) in the radial artery, the performance of a device based on the principle of volume-compensation was assessed by comparison with simultaneous measurement of direct (invasive) radial artery pressure in nine healthy subjects. Bias and precision of systolic BP (SBP) and diastolic BP (DBP) derived from Bland-Altman plots of data from the present system and the direct method averaged -0.5 +/- 2.1 mmHg and 0.6 +/- 1.8 mmHg respectively, over a wide range of SBP and DBP. These results clearly indicate that, using this system, instantaneous radial artery pressure can be measured noninvasively with high accuracy.     

Proposal of a multi-core model for polymer nanocomposite dielectrics

A multi-core model, i.e. a simplified term of a multi-layered core model, is proposed as a working hypothesis to understand various properties and phenomena that polymer nanocomposites exhibit as dielectrics and electrical insulation. It gives fine structures to what are called "interaction zones". An interfacial layer of several tens nm is multi-layered, which consists of a bonded layer, a bound layer, and a loose layer. In addition, the Gouy-Chapman diffuse layer with the Debye shielding length of several tens to 100 nm is superimposed in the interfacial layer to cause a far-field effect. Nano-particles may interact electrically with the nearest neighbors each other due to this effect, resulting in possible collaborative effect. Such a multi-core model with the far-field effect is discussed, for example, to explain partial discharge (PD) resistance of polyamide layered silicate nanocomposites, and is verified to demonstrate its effectiveness.     

500-kV long-distance cable completed in Japan

The first 500-kV long-distance cable line is described. This oil filled self-contained cable has been installed along the Seto-Ohashi bridge connecting Shikoku, the fourth largest of the four major islands that constitute Japan with Honshu, the main island. The power flow will generally be from Shikoku where there is a surplus of power to Honshu, the main island. The technical features of the cable and its installation are described. Polypropylene laminated paper (PPLP), a low-loss insulation paper with high dielectric performance, was adopted, allowing the cable to carry the required transmission capacity of 1200 MW per circuit without forced cooling. The number of splices is also reduced by approximately 40%, resulting in further economy     

Seismic response analysis of full-scale boiling water reactor using three-dimensional finite element method

This paper presents the three-dimensional finite element seismic response analysis of full-scale boiling water reactor BWR5 at Kashiwazaki-Kariwa Nuclear Power Station subjected to the Niigata-ken Chuetsu-Oki earthquake that occurred on 16 July 2007. During the earthquake, the automatic shutdown system of the reactors was activated successfully. Although the monitored seismic acceleration significantly exceeded the design level, it was found that there were no significant damages of the reactor cores or other important systems, structures and components through in-depth investigation. In the seismic design commonly used in Japan, a lumped mass model is employed to evaluate the seismic response of structures and components. Although the lumped mass model has worked well so far for a seismic proof design, it is still needed to develop more precise methods for the visual understanding of response behaviors. In the present study, we propose the three-dimensional finite element seismic response analysis of the full-scale and precise BWR model in order to directly visualize its dynamic behaviors. Through the comparison between both analysis results, we discuss the characteristics of both models. The stress values were also found to be generally under the design value.     

Realization of anti-slip/skid re-adhesion control for electric commuter train based on disturbance observer

Recently, disturbance observer has been used in many system and industry applications. This paper focus on the fine motion control technology based on disturbance observer for electric commuter train. The improvement of adhesion characteristics is important in electric commuter train. We propose the anti-slip/skid re-adhesion control system based on disturbance observer and sensor-less vector control. The effectiveness of the proposed method is confirmed by the experiment based on the actual electric commuter train, which is Series 205-5000 of East Japan Railway Company. Moreover, in order to extend the anti-slip/skid re-adhesion control considering the bogie vibration phenomenon, we propose a new anti-slip re-adhesion control based on the high order disturbance observer considering the resonant frequency of bogie system. Copyright © 2009 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.     

A human‐like numerical technique for design of engineering systems

Because of the necessity for considering various creative and engineering design criteria, optimal design of an engineering system results in a highly‐constrained multi‐objective optimization problem. Major numerical approaches to such optimal design are to force the problem into a single objective function by introducing unjustifiable additional parameters and solve it using a single‐objective optimization method. Due to its difference from human design in process, the resulting design often becomes completely different from that by a human designer. This paper presents a novel numerical design approach, which resembles the human design process. Similar to the human design process, the approach consists of two steps: (1) search for the solution space of the highly‐constrained multi‐objective optimization problem and (2) derivation of a final design solution from the solution space. Multi‐objective gradient‐based method with Lagrangian multipliers (MOGM‐LM) and centre‐of‐gravity method (CoGM) are further proposed as numerical methods for each step. The proposed approach was first applied to problems with test functions where the exact solutions are known, and results demonstrate that the proposed approach can find robust solutions, which cannot be found by conventional numerical design approaches. The approach was then applied to two practical design problems. Successful design in both the examples concludes that the proposed approach can be used for various design problems that involve both the creative and engineering design criteria. Copyright © 2005 John Wiley & Sons, Ltd.     

Electrochemical DNA analysis with a supramolecular assembly of naphthalene diimide, ferrocene, and β-cyclodextrin

Naphthalene diimide 1 bearing ferrocene and β-cyclodextrin (β-CD) was prepared. Its half-wave potential at 420 mV shifted 40-50 mV upon addition of an excess of adamantylamine, suggesting that the ferrocene of 1 is included in the cavity of β-CD intramolecularly to form a pseudocyclic structure. This unique architecture is retained even where 1 is bound to calf thymus DNA to give rise to a catenane-like structure. Morphology of the DNA complex with 1 was further explored by atomic force microscopy to reveal that the DNA strand tends to bend as the amount of 1 on it increases. Presumably, intermolecular, yet intrastrand, inclusion of ferrocene into β-CD is responsible for this phenomenon. The resulting globular structure reverted partially by the addition of adamantylamine. At a low ratio of 1 to DNA, a novel reduction peak appeared at 320 mV in the differential pulse voltammograms of 1 at the expense of the 420 mV peak. The peak current of the former was proportional to the DNA concentration, thereby enabling quantitation of DNA in a signal-on way. Likewise, a polymerase chain reaction (PCR) product of 754 bp was analyzed successfully with a detection limit of 13 nM.     

Analysis of bis(trifluoromethylsulfonyl)imide-doped paramagnetic graphite intercalation compound using F very fast magic angle spinning nuclear magnetic resonance

F atoms bonding to paramagnetic/conductive graphene layers in accepter-type graphite intercalation compounds (GICs) are analyzed using very fast magic angle spinning nuclear magnetic resonance, which is applied for the first time on ¹⁹F nuclei to investigate paramagnetic materials. In the bis(trifluoromethylsulfonyl)imide(TFSI)-doped GIC, C–F bonds between fluorine atoms and graphene layers conform to a weak bonding of F to the graphene sheets. TFSI anions intercalated in the GIC do not show overall molecular motion; even at room temperature only the CF₃ groups rotate.