Showing papers by "Chiba Institute of Technology published in 1991"

Interstitial hyperthermia of malignant brain tumors by implant heating system: Clinical experience

Abstract: An implant heating system using a ferromagnetic implant with low Curie temperature has been developed for treating human brain tumors. Safe and repeated hyperthermia was possible over periods averaging ten weeks in 23 out of 25 patients with malignant brain tumors without development of major side effects. Evaluation of the effects of this new treatment is still preliminary. Overall response rate was 34.8%. However, five of thirteen cases of malignant glioma and two of five cases of brain metastasis were responded well to interstitial hyperthermia given with or without irradiation. Pathological findings common to the treated tumors were circumscribed, ellipsoid shape of coagulation necrosis around the implant. Degeneration of tumor cells, hemorrhage, vascular stasis and thrombosis were found adjacent to the necrosis. In the future, a combination of interstitial hyperthermia with brachytherapy and chemotherapy may offer improved local control of brain tumor.

Encapsulating polymerization of titanium dioxide

Abstract: Titanium dioxide was encapsulated in polymethyl methacrylate and polystyrene by the emulsion polymerization process, and the influence of various polymerization conditions such as the monomer and initiator concentrations and amounts of titanium oxide on the polymerization behavior was investigated. In the polymerization mixture where the end of the polymer chain and the metal oxide surface are oppositely charged, unextractable polymer is formed well. The encapsulating polymers show special structures with high molecular weight and high density. Titandioxid wurde durch Emulsionspolymerisation mit Polymethylmethacrylat und Polystyrol verkapselt. Der Einflus der Monomer-, Initiator-und TiO2-Konzentration und des pH-Wertes der Emulsion wurde untersucht. In den Emulsionen, in denen die Kettenenden und die Metalloxidoberflache entgegengesetzt geladen sind, bildet sich nichtextrahierbares Polymers. Die Kapselpolymeren haben ein hohes Molekulargewicht und eine hohe Dichte, was auf spezielle Strukturen der Polymeren hinweist.

Ergonomic study of automatic teller machine operability

Abstract: In recent years, the most favorable interaction between information systems and people has drawn deep interest. An experimental study was conducted on the adaptation of computer‐based communication to people at the automatic teller machines (ATMs) that are used by the general public. Forty‐two subjects (24 young people, 6 housewives, and 12 elderly people) operated an automatic teller machine in the experiments.

Strong stabilization of systems with time-delays

Abstract: The author presents a design procedure for an internally stable stabilizing compensator (i.e. strongly stabilizing compensator) for scalar time-delay systems with the parity interlacing property. It can be applied to a certain class of the systems with a finite number of unstable zeros. Such a class shows the limitation of the strong stabilization presented using a unit over proper stable rational functions. >

Synthesis and Properties of Non-Hammerhead RNA Using 1-(2-Chloroethoxy)-ethyl Group for the Protection of 2′-Hydroxyl Function

Abstract: The new type protecting group, 1- (2-chloroethoxy)ethyl (Cee) group has been employed for the protection of the 2′-hydroxyl functions of ribonucleoside residues in the synthesis of oligoribonucleotides by the phosphoramidite approach on a solid support, using an acid-labile 5′-dimethoxytrityl group. This group is completely stable under the acidic conditions required to remove the 5′-terminal protecting groups in oligonucleotide synthesis on a solid support, and yet is easily removable under the similar conditions to that of the tetrahydropyranyl (Thp) in the region of pH 2-3 for the final unblocking step. The synthesis of the Cee-protected ribonucleoside 3′-phosphoramidite units proceed smoothly. The Cee-protected ribnucleoside 3′-phosphoramidite units were evaluated in the synthesis of oligoribonucleotides of up to 20 mer residues. The autocleavage of a precursor RNA from bacteriophage T4 (p2Sp1 RNA; precursor of species 1) does not contain the “hammerhead” sequence required for the authocleava...

Compact and high-precision range finder with wide dynamic range using one sensor head

Abstract: A range finder that uses a self-mixing laser diode is described. The range finder has an accuracy of +or-0.13% and a dynamic range of 0.2 m to 1 m and uses only one sensor head. Unlike ultrasonic range finders, the light beam of this laser range finder can be focused and scanned. The feasibility study shows a possible application of the range finder to the visual sensor of a robot. The finder has been successfully applied as an IR active-type range finder of a single-lens reflex camera. >

A car detection system using the neocognitron

Abstract: A car image detection system using the neocognitron is described. The system can recognize car images successfully without regard to influences of the differences of kinds of cars and shifts in position. The number of cell planes can be reduced by actively introducing features of patterns to be recognized by the neocognitron. The neocognitron uses vertical and horizontal lines and combinations as training patterns. The increase of the number of cell planes can thus be held down. Although car images are not directly used in the training process except in the output layer, the system can detect cars skilfully. Thus, using appropriate features of input patterns, the neocognitron obtains sufficient recognition capability. >

Thermal behaviour of TiO2‐encapsulating polymers

Abstract: Comparing the thermal properties of TiO2 encapsulating polystyrene and poly(methyl methacrylate) with those of TiO2 dispersion polymers it was found that the encapsulating polymers have two thermal relaxation regions. The activation energy of those thermal relaxation regions was determined using the Wunderlich method and it was found that the values are similar to the activation energy for the dynamic dispersion. It is suggested that the low-temperature thermal relaxation is caused by the local change of conformation of molecular chains, while the high-temperature thermal relaxation is similar to that of the normal glass transition temperature including the interaction with TiO2. In addition, the thermal behaviour near the degradation point in different atmospheres indicates that the encapsulating polymer has a specific structure for adsorbing a large amount of oxygen. Die thermischen Eigenschaften von Polystyrol and Poly(methylmethacrylat) mit verkapseltem und dispergiertem TiO2 wurden verglichen. Die verkapselnden Polymeren zeigen zwei thermische Relaxationsbereiche, deren nach Wunderlich ermittelte Aktivierungsenergien denen von dynamischen Dispersionen ahnlich sind. Es wird vorgeschlagen, das die Niedertemperaturrelaxation durch lokale Anderungen der Konformation der Makromolekule hervorgerufen wird, wahrend die Hochtemperaturrelaxation dem normalen Glasubergang einschlieslich der Wechselwirkung mit TiO2 vergleichbar ist. Das thermische Verhalten nahe der Zersetzungstemperatur in verschiedenen Atmospharen deutet darauf hin, das in den verkapselnden Polymeren spezifische Strukturen vorhanden sind, die eine grose Menge Sauerstoff adsorbieren konnen.

Electroweak interactions at an infinite sublayer quark level

Abstract: In a previous paper, we proposed the infinite sublayer quark model, in which there exists an infinite number of quarksu ∞ and antiquarksu ∞ at an infinite sublayer level. By applying the standard model of the electroweak interactions to the weak isospin doublet (u ∞,u ∞ ) T it is shown that there exists only one gauge fieldW µ 3 , from which the electromagnetic fieldA µ=W µ 3 cos θ w and the neutral vector boson fieldZ µ 0 =W µ 3 sin θ w are derived.

Wave impedance in the near field around the fundamental electromagnetic radiating elements

Abstract: Standards for electromagnetic protection taking into account human health have been established in a number of countries. Most of the present standards are expressed in terms of the intensities of electric and magnetic fields or the power density of the irradiating electromagnetic field. Usually, for conversion among these quantities, the relationship in the electromagnetic field at a distance far away (far field, plane wave) is used. However, near the electromagnetic source where the electromagnetic wave is the strongest, the relationship among the forementioned quantities varies depending on the location of the observation point or the type of the source. Therefore, there are recommendations to reconsider the standard values. The purpose of this paper is to provide fundamental references for modeling the electromagnetic sources in various electromagnetic equipment to reconsider the protection standard of the near field, and to develop the electromagnetic shielding theory in the near field. In this paper, the distance characteristics and the spatial distribution of the electromagnetic wave impedance characterizing the nature of the electromagnetic wave are studied near the elementary radiating elements such as the electric dipole, magnetic dipole, half-wave dipole antenna, small current loop and small helical antenna.

Two-dimensional computer modeling of discharge-excited CO gas flow

Abstract: In order to simulate and predict the complex mechanism of the high power CO laser excited by transverse dc discharge, a two-dimensional gas flow model has been developed from the authors' one-dimensional model. Based on the control volume method for two-dimensional Cartesian coordinates, the fundamental equations deal with state, continuity, momentum, energy, and reactions. The similar discharge power distribution can be given as the experiment, where the power density is higher around the hollow-cathode array than around the plane anode. Although the speed of the CO gas mixture is in the sub-sonic region, the effect of compression is taken into account. The integration is repeated by SIMPLEST method and the matrices are solved by MICCG method for the pressure equation and by MILUCR method for the other equations. The computation is carried out by a HITAC S820 supercomputer and a Sun-4 workstation. As a result of the simulation, non-uniform distribution of the gas parameters was made clear.

The technologies for active noise control

Abstract: This paper reviews the progress in the technology of active noise control (ANC) with some examples and discusses what are the key points in this technology. In the first place, the principle of the ANC is briefly explained and it is shown that the cancellation of noise by the sound wave radiated by the additional sound source can be considered to be equivalent to the control of the internal impedance of additional sound source. And an example of the noise control by the adaptive directivity control is explained. Then, some method to decrease the closed loop gain are shown as the instability is usually fatal in the ANC system. Next, the FIR filter to synthesize the signal to drive the additional source is introduced as an indispensable equipment. It is finally pointed out that the adaptive control of the coefficients of FIR filter is the most important technology in the active noise control because the optimum values of the coefficients vary with the changes in the noise transmission path.

Electric field-assisted and field-depressed segregation of reactive metals to the bonding interface in braze alloy joining

Abstract: Segregation of reactive metals at the bonding interface has been observed in various ceramic and/or metal joints bonded with reactive metal-bearing braze alloys. When a d.c. of 20 mAcm−2 is applied to the ceramic/braze/ceramic system at a brazing temperature of, say, 1373 K, the electric field assists the segregation at the braze-ceramic interface on the cathode side and suppresses the segregation at the interface on the anode side. This may imply that reactive metal atoms in the braze can migrate as a cation. E.m.f. measurement on the ceramic (AIN or ZrB2)-metal foil systems with increasing temperature shows that a negative e.m.f. to the ceramic pole appears from about 900 K for AIN and from 500 K for ZrB2, as does the thermally stimulated current in polymers. These temperatures coincide well with those where the electrical conductivity of AIN and ZrB2, respectively, begins to increase with increasing temperature. Therefore, it is considered that the polarization of the ceramics may take place and assist the migration, and consequently segregation, of reactive metals in braze alloys to the braze-ceramic interface during brazing.

A variable step gain algorithm with fuzzy control

Abstract: Numerous methods for a parameter estimation in adaptive signal processing have been proposed. LMS, learning identification method, etc., for example, often are used due to easiness of their hardware construction, but their estimation speed and estimation accuracy vary by contrast depending on the magnitude of the coefficient called step gain. As a method for resolving it, a variable step (VS) algorithm in which the step gain is changed according to the parameter estimation condition has been proposed. However, since the variables in these algorithms that are intended to express the estimation conditions do not fully do so, it remains difficult to control the step gain appropriately. This paper defines anew variables to detect the change of parameters and disturbance and to comprehend the parameter estimating condition, and proposes a variable step algorithm for controlling the step gain by fuzzy controller with these variables as fuzzy input. Furthermore, computer simulation is implemented by applying this method to the learning identification method to show its effectiveness. In particular, with this algorithm we do not need to change the algorithm to deal with variations of the statistical properties of the input signal, and the computational complexity does not depend on the order of the filter; thus it is advantageous for higher-order identification. Moreover, we have observed that it can cope with observation of noise, rapid change of unknown parameter, and it improves estimation speed by about 15 percent and estimation accuracy by about 20 percent compared with those of existing VS algorithms.

Transport Rate of Gaseous Phosphorus into Solid Iron under Reducing Atmosphere

Abstract: Transport rate of gaseous phosphorus into solid iron under reducing atmosphere was observed by a gravimetric procedure to obtain fundamental data to discuss transport mechanism of phosphorus into reduced iron in a blast furnace.A kind of killed and rolled steel sheet and non worked electrolytic iron sheet were used as samples. Partial pressure of phosphorus vapor was controlled by using equilibrium relation between PP2, Ca3 (PO4)2, SiO2, C, CaSiO3 and CO. Phosphorus partial pressure and temperature were every one order between 4×10–6 and 4×10–2 atm, and every 50°C between 900 and 1050°C, respectively.Experimental results are as follows:(1) Transport rate obeyed a parabolic rate law.(2) Relations between the rate constants of the parabolic rate law, k, the phosphorus partial pressure, PP2, and the temperature, T, are as follows:In the case of killed steel, log k=0.14 log PP2+5.68–15.6 ×103/TIn the case of the electrolytic iron, log k=0.14 log PP2+4.94–15.6×103/T(3) Reaction product on a surface of solid iron was Fe2P.

One-D and two-D computer models of industrial CO laser

Abstract: Computer models have been developed for the industrial CO lasers, those are oparated by transverse dc discharge in the temperature region 1 50-200 K. The 1D (dimensional) model has been developed to analyze and predict the output performance characteristics, mainly the laser power. The flow equations are coupled with the kinetic equations of the direct excitation by electron impact in discharge, V-V (vibration to vibration) and V-R/T (vibration to rotation and translation) energy transfer by collision, and spontaneous and stimulated emission. The 2D model to analyze the spatial distribution of the gas temperature and excited molecules is now under development. The flow equations, based on the control volume method for the 2D Cartesian coordinates, are described. The time integration is performed by the SIMPLEST method.

A robust adaptive algorithm, for block signal processing

Abstract: An analysis is made of the behavior of a block orthogonal projection algorithm (BOPA) applied to a practical system in which the input signal is smooth-colored and additive noise is observed at the output of an unknown filter. Using this result, a block adaptive algorithm is presented. This algorithm is based on singular-value decomposition and obtained by truncating several smaller singular values. >