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The formability of deep drawn ultra-high strength steel sheets in dies coated with either titanium nitride (TiN) or Vanadium carbide (VC) at different drawing speeds and ironing ratios was investigated. TiN was deposited via chemical vapour deposition and physical vapour deposition (PVD) while thermal diffusion was used for VC deposition. In non-coated dies, seizure occurred on both surfaces of the die and the side wall of the drawn cup irrespective of the deep drawing conditions. The deep drawability is improved with coating of die. Whereas in coated dies, seizure became significant only during deep drawing extreme conditions of 120 mm/s for TiN-coated dies; and this was prevented in VC-coated dies across all drawing conditions. The VC-coated die was suitable for deep drawing of ultra-high strength steel sheets. The delayed fractured observed in the ultra-high strength steel cups occurred for a large amount of ironing ratio and drawing speeds; and this can be prevented by appropriate heat treatment.

Interplanetary scintillation (IPS) measurements of the solar wind speed for the distance range between 13 and 37 R S were carried out during the solar conjunction of the Nozomi spacecraft in 2000 – 2001 using the X-band radio signal. Two large-aperture antennas were employed in this study, and the baseline between the two antennas was several times longer than the Fresnel scale for the X-band. We successfully detected a positive correlation of IPS from the cross-correlation analysis of received signal data during ingress, and estimated the solar wind speed from the time lag corresponding to the maximum correlation by assuming that the solar wind flows radially. The speed estimates range between 200 and 540 km s−1 with the majority below 400 km s−1. We examined the radial variation in the solar wind speed along the same streamline by comparing the Nozomi data with data obtained at larger distances. Here, we used solar wind speed data taken from 327 MHz IPS observations of the Solar-Terrestrial Environment Laboratory (STEL), Nagoya University, and in situ measurements by the Advanced Composition Explorer (ACE) for the comparison, and we considered the effect of the line-of-sight integration inherent to IPS observations for the comparison. As a result, Nozomi speed data were proven to belong to the slow component of the solar wind. Speed estimates within 30 R S were found to be systematically slower by 10 – 15 % than the terminal speeds, suggesting that the slow solar wind is accelerated between 13 and 30 R S.

The L/sub 2/-norm pyramid has already been investigated as a promising data structure for the fast search of vector quantization (VQ) encoding in the previous work. Because the distortion at the top level is always tested first when using such a conventional L/sub 2/-norm pyramid, the top level is most important. In order to enhance the capability of achieving a rejection decision at the top level, a modification is introduced into the conventional L/sub 2/-norm pyramid in this letter by using both the mean and the variance of a vector simultaneously to replace the L/sub 2/-norm of the vector for distortion computation at the top level. Two issues are made clear as 1) why this modification is beneficial to the distortion test is proved and 2) why only the top level of a conventional L/sub 2/-norm pyramid should be modified is interpreted as well. Experimental results confirmed that the performance of VQ encoding by using the modified L/sub 2/-norm pyramid can be improved obviously.

Thirteen synoptic maps of expansion rate of the coronal magnetic field (CMF; RBR) calculated by the so-called ‘potential model’ are constructed for 13 Carrington rotations from the maximum phase of solar activity cycle 22 through the maximum phase of cycle 23. Similar 13 synoptic maps of solar wind speed (SWS) estimated by interplanetary scintillation observations are constructed for the same 13 Carrington rotations as the ones for the RBR. The correlation diagrams between the RBR and the SWS are plotted with the data of these 13 synoptic maps. It is found that the correlation is negative and high in this time period. It is further found that the linear correlation is improved if the data are classified into two groups by the magnitude of radial component of photospheric magnetic field, |Bphor|; group 1, 0.0 G ≦ |Brpho| < 17.8 G and group 2, 17.8 G ≦ |Brpho|. There exists a strong negative correlation between the RBR and the SWS for the group 1 in contrast with a weak negative correlation for the group 2. Group 1 has a double peak in the density distribution of data points in the correlation diagram; a sharp peak for high-speed solar wind and a low peak for low-speed solar wind. These two peaks are located just on the axis of maximum variance of data points in the correlation diagram. This result suggests that the solar wind consists of two major components and both the high-speed and the low-speed winds emanating from weak photospheric magnetic regions are accelerated by the same mechanism in the course of solar activity cycle. It is also pointed out that the SWS can be estimated by the RBR of group 1 with an empirical formula obtained in this paper during the entire solar activity cycle.

Vector quantization (VQ) is a famous asymmetric signal compression method. In VQ, the search process to find the winner for an input vector is extremely time consuming due to a lot of k-dimensional Euclidean distance computations. This property of VQ constrains its practical applications to some extent. In order to speed up the search process of VQ, a unified projection method is proposed in this letter to reject a candidate code vector by a lighter computational burden. This method is universal because it can unify several types of previous works through suitably selecting a projection axis. Furthermore, two criteria for how to select an optimal projection axis for a code vector are proven mathematically, which are most important because they demonstrate the direction for a potential improvement to the search efficiency of VQ. Experimental results of VQ encoding show that the proposed method is very search effective.

Vector quantization (VQ) is a well-known signal compression method. In VQ, the search process to find the winner for an input vector either at the codebook generation stage or the VQ encoding stage is extremely time consuming. By using the law of cosines to estimate the Euclidean distance first, Mielikainen has developed a highly efficient full-search-equivalent algorithm. However, some computational redundancies still exist in it. In this letter, we introduce an additional new estimation for the Euclidean distance and then optimize the computing way given by Mielikainen. Mathematical analyses show that our proposed search method can improve Mielikainen's method. And experimental results of VQ encoding demonstrate that the proposed method is very search effective.

The origin and location of the slow wind are interesting subjects on their own and also they are important in the matter of the origin of the fast wind especially if the slow wind originates directly from a coronal hole. We have been studying the solar wind whose speed is comparative to or a little slower than that measured in the heliospheric plasma sheet. We derived solar wind velocity distribution maps on the source surface using an interplanetary scintillation tomography analysis, and low speed regions in them were investigated in relation to a coronal hole using potential field magnetic field lines. Slow solar wind was found to originate from an equatorial coronal hole located in the vicinity of active regions and also from a polar coronal hole which was about to disappear at solar activity maximum. The properties of the slow solar wind from an equatorial coronal hole were investigated using spacecraft in situ measurements. Magnetic polarity in this wind was uniform, as expected from a potential field analysis. The helium relative abundance was as large as the fast wind, and variances of density, velocity, and helium abundance were as small as the fast wind from a large coronal hole. In spite of the small equatorial coronal hole origin, the density and ion freeze-in temperature were as large as observed for the slow wind in the heliospheric plasma sheet.

Relationships between solar wind speed and expansion rate of the coronal magnetic field have been studied mainly by in-ecliptic observations of artificial satellites and some off-ecliptic data by Ulysses. In this paper, we use the solar wind speed estimated by interplanetary scintillation (IPS) observations in the whole heliosphere. Two synoptic maps of SWS estimated by IPS observations are constructed for two Carrington rotations CR 1830 and 1901; CR 1830 starting on the 11th of June, 1990 is in the maximum phase of solar activity cycle and CR 1901 starting on the 29th of September, 1995 is in the minimum phase. Each of the maps consist of 64800 (360×180) data points. Similar synoptic maps of expansion rate of the coronal magnetic field (RBR) calculated by the so-called ‘potential model’ are also constructed under a radial field assumption for CR 1830 and CR1901. Highly significant correlation (r=−0.66) is found between the SWS and the RBR during CR1901 in the solar minimum phase; that is, high-speed winds emanate from photospheric areas corresponding to low expansion rate of the coronal magnetic field and low speed winds emanate from photospheric areas of high expansion rate. A similar result is found during CR 1830 in solar maximum phase, though the correlation is relatively low (r=−0.29). The correlation is improved when both the data during CR 1830 and CR 1901 are used together; the correlation coefficient becomes −0.67 in this case. These results suggest that the correlation analysis between the SWS and the RBR can be applied to estimate the solar wind speed from the expansion rate of the coronal magnetic field, though the correlation between them may depend on the solar activity cycle. We need further study of correlation analysis for the entire solar cycle to get an accurate empirical equation for the estimation of solar wind speed. If the solar wind speed is estimated successfully by an empirical equation, it can be used as an initial condition of a solar wind model for space weather forecasts.

The tomographic analysis of interplanetary scintillation (IPS) showed that low-speed winds (< 370 km s -1 ) emanated out from the polar region at the last solar activity maximum. In order to investigate the origin of those low-speed winds, we compared the velocity distribution derived from the IPS tomographic analysis to the magnetic field structure derived from the potential field analysis. We found that the polar low-speed winds appeared for a short period just before and after the disappearance of polar open fields. When the polar coronal hole shrank very small before its disappearance, the coronal polar open field was encircled by large-scale closed loops and became super radially diverging field into the interplanetary space. A low-speed region appeared in this diverging polar magnetic field region. This situation is a condition very similar to the compact low-speed streams associated with equatorial active regions, which were found by Kojima et al. [1999]. After the open field regions had disappeared from the pole, the polar regions were occupied with closed loops. These closed loops were overlapped by the magnetic field which fanned out from the midlatitudes. A low-speed streamer located above these closed loops even after the polar open field had disappeared. The velocities of polar low-speed streams before polar hole disappearance were much lower than those after disappearance. This result suggests that the physical conditions to generate much lower speed streams are closely associated with large expansion from small open field regions encireled by large-scale closed loops. Finally, a reliability of the IPS measurement of polar low-speed wind was examined by simulating synthetic IPS observations in hypothetical model polar streams.

The Ulysses spacecraft observed high-speed wind at high latitudes up to 80° and found that the high-speed solar wind increased in velocity gradually with latitude and that the velocity had asymmetry between Northern and Southern Hemispheres. We have investigated the velocity increase up to the polar regions for the Carrington rotations of 1908-1915 in the year 1996. For this purpose we have made tomographic analyses of the latitudinal structure of the solar wind speed using interplanetary scintillation data obtained at heliocentric distances of 0.1-0.9 AU and latitudes up to 90°. The tomographic analysis method was modified from its previous version [Kojima et al., 1998] so that it could obtain more reliable solutions with better sensitivity in the polar region than the previous method. The results from the observations in 1996 showed that the velocity increased with latitude and had the N-S asymmetry as observed by Ulysses. These features persisted during the period analyzed. Since the asymmetry was found in rather short period observations of several Carrington rotations and at distances within 0.9 AU, it is caused neither by temporal evolution of the solar wind structures nor by interactions in the solar wind in interplanetary space. These global latitudinal velocity structures agree qualitatively with the magnetic flux expansion factor.

We demonstrated that the organic carbon contaminants influenced the J-E characteristics of a gate oxide. Molecular-contamination-free clean dry air (CDA) is a choice for the atmosphere control in a closed manufacturing system. The adsorption and desorption characteristics, which are important items for the design and operation of CDA production plants, were confirmed with both a dynamic simulation and a pilot column. Based on the results, we built a CDA plant with a capacity of 4000 m/sup 3//h, and confirmed that each contamination concentration was less than 10 ppb. We also proposed the economical CDA system using a power recycle device which has been newly developed. Using this CDA system, it is possible to reduce the power consumption in the CDA plant. Also, it is possible to realize the circulation of the used CDA without generating more contamination or power consumption.

Interplanetary scintillation measurements at 327MHz taken in 1997 are used to study the large-scale heliospheric structure near the solar activity minimum. Our data show that density fluctuations in the fast polar wind is much less than those of the slow wind around the equator. The reduction ratio of the fast wind turbulence is estimated to be about 0.53 from the model calculation. While an inverse relation between wind speed and density fluctuations appears to exist, the correlation is weak, and there are significant discrepancies in the locations of high turbulence and slow wind speed. This discrepancy might come from the integration effect along the line-of-sight and/or the effect of the stream-stream interaction.

Solar wind velocity distributions were derived on the source surface from interplanetary scintillation observations using a tomographic analysis method to investigate the positional relation of compact low-speed regions with active regions and large-flux-expansion regions. It is shown that the compact low-speed regions are better associated with large-flux-expansion regions, and they are found near active regions.

Alumina films have been successfully formed on austenitic stainless steels containing 4 and 5 wt % Al by selective oxidation of Al in a H2O/H2 environment. γ-alumina films have been formed by oxidation at 800 °C and δ-alumina films at 900 °C. Satisfactory corrosion resistance performance for ozone gas has been obtained for both γ- and δ-alumina films. For ozonized water, δ-alumina films formed with pH2O/pH2⩽1×10−4 have good corrosion resistance while δ-alumina films formed with pH2O/pH2⩾3×10−4 or γ-alumina films do not. Holes of a characteristic triangular shape are observed on the oxidized surface of stainless steels containing 4 wt % Al, probably caused by the habitual formation of precipitated β-(Fe,Ni)Al. No such hole has been observed on the oxidized surface of stainless steels containing 5 wt % Al.

We investigated the deposition condition of the plasma processing for the formation of as-grown poly-Si thin film on the SiO2 substrate with low temperature (300 °C) processing. We intended to compensate the thermal energy loss due to the low temperature processing with the low kinetic energy ion bombardment assist. We adopted both plasma enhanced chemical vapor deposition (PECVD) (SiH4/Ar/H2) and sputtering (Si-target/Ar/H2) processes. Plasma parameters were measured by the advanced Langmuir probe method tuned for 182.5 MHz rf plasma. Crystallinity of the film was estimated mainly by x-ray diffraction. Crystallization occurred by in situ hydrogenation during the deposition. In our experiment, ion bombardment energy was approximately 23 eV. We define the normalized ion (ni) flux number and investigated the correlation between the ni and the film crystallinity. The result is as follows, the crystal size enlarges with the increasing ni up to ∼20 but it diminishes as the ni increases over ∼20. Under the same...

A CMOS operational amplifier employing the multiple-input-terminal transistor called neuron MOSFET (or /spl nu/MOS) as pair transistors has been developed. The circuit can perform a variety of analog voltage summation/subtraction operations in a very simple circuitry. The self-offset-cancellation capability has been implemented by a clocked /spl nu/MOS technique. As a result, high-accuracy voltage-mode signed-digit computation has become possible. The /spl nu/MOS operational amplifier has been applied to build a carry-propagation-free multivalued full adder circuit based on the radix-4 seven-valued signed-digit number system. The circuit operation has been verified by test circuits fabricated by Tohoku University standard double-polysilicon CMOS process with a 3 /spl mu/m rule.

Polycrystalline silicon thin films have been deposited on silicon oxide at 300°C by very high frequency (182.5 MHz) sputtering using an Ar and H 2 gas mixture and an arsenic-doped Si wafer target. Characteristics of films are affected by the hydrogen partial pressure, and polysilicon of lowest resistivity is obtained at 20 to 30% hydrogen partial pressure ratio. We found that as the hydrogen content of the film is reduced, resistivity decreases. This is attributed to reduction of amorphous grain boundary regions due to better crystallization. It is also found that the normalized ion flux incident on the growing surface varies with hydrogen partial pressure, an important parameter for determining the properties of as-deposited polysilicon.

We have measured magnetic field distortion of the order parameter and the longitudinal resonance frequency of superfluid {sup 3}He-{ital B} using pulsed nuclear magnetic resonance. The experiments were guided by numerical solutions of Leggett{close_quote}s equations which we have generalized to include gap distortion. We have found stable regions for the nonlinear spin dynamics and taken advantage of this to obtain the first measurements of the temperature dependence of the distortion of the energy gap in the {ital B} phase. At low temperatures and pressures the results agree with theoretical predictions of Fishman and Sauls. {copyright} {ital 1996 The American Physical Society.}

Quantitative estimation of non-repeatable runout (NRRO) in head tracking mode on the hard disk drive was performed by an experimental investigation of ball-bearing spindle motor NRRO. The characteristic difference between the spindle motor NRRO and the head tracking error is discussed. This head tracking error is caused by the NRRO in tracking mode and NRRO in servo track writing, taking head tracking control into account. The amplitude of spindle motor NRRO is 130 nm peak-to-peak in this experiment. While the low frequency components of NRRO caused by bearing geometry are compressed, rotor resonance frequency vibrations are predominantly enhanced by the characteristics of the sensitivity function of the head positioning system. The amplitude of the error caused by the motor NRRO is twice as large as that of the motor NRRO itself. Neither of the probability density functions, namely motor NRRO and tracking error caused by NRRO, is Gaussian distribution.

The technology for neutralizing static electricity by soft X-ray radiation and vacuum UV radiation has been newly developed. This technology involves ionization of gas molecules in the vicinity of a charged substrate to generate ions and electrons to reduce electrostatic potential. The ULSI device substrate and the liquid crystal display substrate tend to get charged instantly to a high electric potential level (of several kVs) when they are handled in the manufacturing process. The amount of electric charge induced on their surface when they get charged, however, is small. This means the concentration of ions and electrons required for neutralization is considerably low. The wavelength of electromagnetic radiation to be utilized in neutralization is varied, depending on the neutralization atmosphere. Soft X-ray radiation is adequate in air or O2 gas at atmospheric pressure while vacuum UV radiation is effective in N2 gas, Ar gas, or at reduced pressure. This newly developed neutralization method is found to be superior to the conventional technique, i.e., an ionizer by using corona discharge, in every aspect. The new method features excellent neutralization capability and is able to completely reduce electrostatic potential to 0V within a short time. Moreover, this is a very clean antistatic technology free from particle generation, ozone generation, and electromagnetic noise, which are problems in using the corona discharge ionizer.

It is shown that the anomalous negative cw-NMR frequency shift observed in U2D2 solid 3He is a manifestation of thermal fluctuations of the spin and the antiferromagnetic vector. The limits of the hydrodynamic description are discussed, and a formula for the anomalous shift is obtained for a specific orientation of the magnetic field where the hydrodynamic shift vanishes.

The adhesion and removal behavior of metallic impurities on a PFA sheet surface was examined with TRXRF analysis. Metals such as Fe and Cu are strongly adhered, and they can be removed to some extent by SPM or FPM cleaning. The surface metallic concentration of PFA sheets did not increase when they were dipped into UPW or chemicals contaminated with metals, therefore it is assumed that metallic impurities do not adhere to the PFA surface from liquids. Moreover the metallic transfer tests showed that a cleaned PFA sheet did not contaminate Si wafers but an uncleaned sheet polluted the wafer strongly with metallic impurities. Therefore, when PFA molded parts such as wafer carriers and tubes are used in wet processing in semiconductor manufacturing, they must be cleaned by SPM or FPM cleaning

Thin polyoxide films grown at 400/spl deg/C on n/sup +/-poly-Si films, used as gate insulators in MOS capacitors, are shown to exhibit superior performance, with respect to conventional, thermally grown polyoxide films at 900/spl deg/C, i.e., they possess lower leakage currents and can sustain higher electrical fields. They are also shown to be superior to, either polyoxide films grown at 980/spl deg/C on substrates treated by chemical mechanical polishing (CMP) or polyoxide films grown by electron cyclotron resonance (ECR) nitrous oxide plasma at 400/spl deg/C. The present film growth techniques utilize oxygen radicals (O*), rather than oxygen molecules (O/sub 2/), which are used in conventional processing. The oxygen radicals are generated by microwave (2.45 GHz) excited high-density plasma of Kr/O/sub 2/ gas mixture.

As part of an effort to produce a static-free wafer spin-dryer the authors developed an ionizer for use with spin-dryers and evaluated its charge removing and particle rejecting effects. Particle generation due to sputtering of the discharge electrodes themselves was prevented. The protection of the discharge electrodes with quartz glass completely prevents particle generation by ion and electron sputters, and the concentration of ozone generated is reduced to less than 1/10 of the usual level. This ionizer is excellent in its charge-removing performance taking only about 1 s to reduce the wafer potential from +or-5 kV to +or-0.1 kV. The residual potential due to the imbalance of ion polarity is extremely low, only 10 V at the maximum. The ionizer's charge removing effect to prevent particle deposition was also evaluated, and almost complete success is reported in preventing the statically induced deposition of particles to wafers while they are being dried by a spin-dryer. >

A design methodology for a bipolar imaging device, the base-stored image sensor (BASIS), has been established by theoretical analysis and experimental verification for random noise. The random noise in BASIS is dominated by the shot noise in readout and transient reset operation. The theoretical analysis has been carried out by introducing the probability density functions for these operations. The readout noise depends on the base-to-collector junction capacitance C/sub bc/, the emitter common current gain h/sub FE/, the storage capacitor C/sub T/, and the emitter voltage V/sub E/. The reset noise has been confirmed to be given by thermal noise. The theoretical results coincide well with the experimental results obtained by TEG devices. An expression for the S/N ratio has been derived theoretically. It is found that h/sub FE/ should be made as large as possible and (C/sub bc/+C/sub be/) as small as possible to improve the S/N ratio for random noise, where C/sub be/ is the base-to-emitter junction capacitance. >

In this paper, a new approach to reduce the 1/f noise levels in the MOSFETs on varied silicon orientations, such as Si(100) and (110) surfaces, has been carried out. We focus on the Accumulation‐mode (AM) FD‐SOI device structure and demonstrate that the 1/f noise levels in this AM FD‐SOI MOSFETs are obviously reduced on both the Si(100) and (110) surfaces.

Evidence for the emission of slow muonium atoms from a 3.0-nm-thick SiO2 layer covered on an n-type Si is reported. Also, upon applying an rf-resonance technique at the muon frequency, a time-differential observation of a delayed state-change from muonium to diamagnetic muon at room temperature was observed. Combining results obtained by use of longitudinal field decoupling and transverse spin rotation methods, the conversion rate was estimated to be 5 to 10 μs−1. Both of the above results, namely the observation of the emission and state-change of muonium, suggest a process in which μ+ initially captures an electron from Si, then quickly converts to μ+ again during thermal diffusion in the Si towards the SiO2 layer. Within the oxide layer, muonium is again formed and subsequently is emitted from the SiO2 surface.

VQ is a famous signal compression method. The encoding speed of VQ is a key problem for its practical application. In principle, the high dimension of a vector makes it very expensive computationally to find the best-matched template in a codebook for an input vector by Euclidean distance. As a result, many fast search methods have been developed in previous works based on statistical features (i.e. mean, variance or L/sub 2/ norm) or multi-resolution representation (i.e. various pyramid data structures) of a vector to deal with this computational complexity problem. Therefore, how to use them optimally in terms of a small memory requirement and a little computational overhead becomes very important. This paper proposes to combine both the 2-PM sum pyramid and (n/spl times/n)-PM variance pyramid of a vector to construct a new mixed pyramid data structure, which only requires (k+1) memories for a k-dimensional vector. Experimental results confirmed that the encoding efficiency by using this mixed pyramid outperforms the previous works significantly.

The encoding process of image vector quantization (VQ) is very heavy due to it performing a lot of k-dimensional Euclidean distance computations. In order to speed up VQ encoding, it is most important to avoid unnecessary exact Euclidean distance computations as many as possible by using features of a vector to estimate how large it is first so as to reject most of unlikely codewords. The mean, the variance, L 2 norm and partial sum of a vector have been proposed as effective features in previous works for fast VQ encoding. Recently, in the previous work (Z. Lu et al., 2003), three features of the mean, the variance and L2 norm are used together to derive an EEENNS search method, which is very search efficient but still has obvious computational redundancy. This paper aims at modifying the results of EEENNS method further by introducing another feature of partial sum to replace L2 norm feature so as to reduce more search space. Mathematical analysis and experimental results confirmed that the proposed method is more search efficient compared to (Z. Lu et al., 2003)

It is demonstrated that ultra clean technology is a crucial factor in developing high quality processing technology for future ULSI fabrication. Simultaneous establishment of three principles, i.e., ultra clean processing environment, ultra clean wafer surf ace, and perfect processparameter control, only makes it possible to realize high quality processing. Such high quality processing technologies are recognized to be essentially required for deep submicron ULSI and advanced power device manufacturing. In accordance with the development of advanced microfabrications based on the ultra clean technology, temperatures of key processings are lowered less than 50OoC. so that buried metal structures becomes practical to be introduced to power devices in order to improve the speed performance due to the decrease of the electrode resistance.

Impurity back diffusion through a UHV pump in reduced-gas-processing chambers has been experimentally studied. A large throughput of process gases severely degrades the main UHV pump capability in dragging impurities, resulting in the back diffusion of impurities to the processing chamber. Such degradation is greatly influenced by the pumping speed of the backing pump. However, we have found for the first time that the impurity level in the chamber can be made even lower than that for the best performance under UHV when the gas flow rate is optimized for the system. The scenario to the gas pumping system optimization is presented.

The encoding process of vector quantization (VQ) is a time bottleneck to its practical application. In order to speed up the process of VQ encoding, it is possible to estimate the Euclidean distance first with just a lighter computation to try to reject a candidate codeword. In order to estimate the Euclidean distance, appropriate features of a vector become necessary. By using the famous statistical features of the sum and variance for a k-dimensional vector and furthermore for its two corresponding (k/2)-dimensional subvectors, it is easy to estimate the Euclidean distance so as to reject most of the unlikely codewords for a certain input vector (Guan, L and Kamel, M., 1992; Lec, C.H. and Chen, L H., 1994; Baek, S. et al., 1997; Pan, J.S. et al., 2003). Because it is very heavy to compute the variance of a k-dimensional vector online, a new feature, which is based on the variances of two subvectors, is constructed to estimate the Euclidean distance. Meanwhile, a modified more memory-efficient data structure is proposed for storing all features of a vector to reduce extra memory requirement compared to the latest previous work (Pan, J.S. et al., 2003). Experimental results confirmed that the proposed method is more search efficient.

In a framework of vector quantization (VQ), the fast search method for finding the best-matched codeword (winner) is a key issue because it is the time bottleneck for practical applications. To speed up VQ encoding process, some fast search methods that are based on the concept of projection axes or Walsh transform have already been proposed in previous works (L. Guan and M. Kamel, Oct 1992)-(S. Baek and K. Sung 2001). However, there still exist two serious problems in them because they use both spatial domain and partial Walsh domain simultaneously. First, they need extra memories for storing projected values on selected projection axes or the first several elements in partial Walsh domain, which becomes an overhead of memory. Second, once all rejection tests fail finally, they completely discard the obtained distortion that has already been computed in partial Walsh domain and return to spatial domain to compute real Euclidean distance again from the very beginning, which is certainly a waste and becomes an overhead of computation. In order to solve the overhead problems of both memory and computation as described above, firstly a memory-efficient storing way for a vector is proposed by completely mapping a vector into Walsh domain but NOT using-the original spatial domain any more, which can avoid extra memory requirement Secondly, the discarded distortion in partial Walsh domain is reused so as to avoid any waste to the executed computation. In addition, a more efficient rejection test is suggested to reduce more search space. Experimental results confirmed that the proposed method outperforms the previous works obviously.

Vector quantization (VQ) is a well-known signal compression method. The encoding process of VQ is extremely time-consuming so that it limits the practical applications of VQ method to a great extent. In order to speed up the process of VQ encoding, the previous works (J.Z.C. Lai, et al, IEEE Trans. Image Processing, Vol. 13, No. 12, pp.1554-1558, 2004; S.J. Back, et al, Signal Processing, Vol.75, pp.89-92,1999) have reported that the projection concept of a vector is very effective for rejecting most of unlikely candidate codewords to speed up VQ encoding process. In both of these two previous works, they used a set of three symmetric projection axes or generalized central axes like p/sub 1/ = [111111111111111]/sup T/, P/sub 2/ = [11111111-1-1-1-1-1-1-1-1]/sup T/ and p/sub 3/ = [11-1-111-1-111-1-111-1 -1]/sup T/ for rejection tests in the case of 4/spl times/4 block size. In addition, they reported that if and only if these three axes of (p/sub 1/, p/sub 2/, p/sub 3/) can experimentally guarantee the best search performance of VQ encoding. However, both of these two previous works did not give out the reasons to show why this set of (p/sub 1/, p/sub 2/, p/sub 3/) axes is the best choice for projection axes. It is a remaining important problem in the two previous works. This paper aims at providing a verification and an explanation to the best choice of (p/sub 1/, p/sub 2/, p/sub 3/) set and meanwhile proposing a criterion on how to choose the projection axes optimally based on the concept of Walsh transform. Experimental results confirmed the effectiveness of the proposed criterion.

The encoding speed of vector quantization (VQ) is an important problem for VQ's practical applications. Because a k-dimensional (k-D) vector can also be mathematically viewed as a k-element set so that the statistical analysis methods can be directly applied to k-D vectors. In order to approximately measure the difference between two k-D vectors, by using the well-known statistical features of the sum and the variance of a k-D vector first, the IEENNS method (S. Baek, et al., IEEE Signal Processing Letters, vol.4, pp.325-327, 1997) has been proposed to reject most of unlikely codewords for a certain input vector. Then, by dividing a k-D vector in half to generate its two corresponding (k/2)-D subvectors and then apply the IEENNS method again to each of the subvectors, a complete-version SIEENNS method (J.S. Pan, et al., IEEE Trans. Image Processing, voL12. pp.265-270, 2003) has been proposed as well. Because the SIEENNS method still has a large memory and computational redundancy, a simplified-version enhanced ESIEENNS method (Z. Pan et al., 2005 International Symposium on Circuits and Systems, pp.6332-6335, 2005) is reported recently. However, all of these subvector-based previous works just fixedly constructed its two subvectors for simplicity, which cannot guarantee a very high search performance. Instead, this paper proposes to dynamically construct the two subvectors more efficiently based on a criterion of |S/sub y,j/ - S/sub y,j/| /spl rArr/ max by offline analyzing the property of a codeword y/sub i/. Experimental results confirmed that the proposed DESIEENNS method can improve the total search efficiency to 79.9% /spl sim/ 88.7% compared to the latest ESIEENNS method for various input images.

The encoding process of vector quantization (VQ) is a time bottleneck to its practical applications due to it performing a lot of k-dimensional Euclidean distance computations. In order to speed up the process of VQ encoding, it is most important to avoid unnecessary exact Euclidean distance computations as many as possible. This purpose can be realized by first estimating how large Euclidean distance is with just a lighter computation, which requires the estimation for Euclidean distance must be less or equal to Euclidean distance itself. Then, if this estimation is sufficiently large, it can lead to a rejection to current candidate codeword. In order to make an estimation for Euclidean distance, appropriate features of vectors are necessary. By using famous statistical features (i.e. the sum and the variance) of a k-dimensional vector and its two corresponding (k/2)-dimensional subvectors to estimate Euclidean distance first, it is possible to reject most of unlikely codewords for a certain input vector as proposed in the previous works. Under the consideration of using the sum and the variance information as features of vectors, a new feature based on the variances of two subvectors is constructed in this paper to set up a new estimation for Euclidean distance. Meanwhile, a memory-efficiency data structure is proposed for storing all features of a vector to avoid any extra memory requirement compared to the latest previous work. Experimental results confirmed that the proposed search method in this paper is more search efficient.

We have investigated pinning effects on texture and vortices of the B-like phase of superfluid (3)He in a rotating aerogel up to +/-2pi rad/s by cw-NMR. We observed deformation of the NMR spectra in rotation, due to counterflow between the superflow and the normal flow. The average intensity of the counterflow was calculated from the change of NMR spectra. The rotation dependence of the counterflow intensity is similar to the magnetization curve of hard type II superconductors or the counterflow response of (4)He-II in packed powders. This counterflow behavior is in qualitative agreement with a model that vortices are pinned unless the counterflow exceeds a critical velocity v(c). The temperature independence of v(c) suggests that v(c) is associated with the expansion of primordial vortices.

[1] We have studied the radial dependence of the velocity of high-latitude fast solar wind in the heliocentric distance range of 0.13–0.9 AU. For this study a new tomographic analysis method which can evaluate uncertainties was developed to obtain velocity distribution maps on two reference spheres at 0.13 and 0.3 AU using interplanetary scintillation (IPS) observations. First of all, it is tested that this tomographic method has enough sensitivity and reliability to investigate the radial dependence of the wind velocity. The analysis was made for the IPS observations during 3 years, from 1995 to 1997, when solar activity was minimum. From this analysis, average velocities of 770–780 km s−1 were obtained at distances of 0.13–0.3 AU, which were 19 ± 17 km s−1 lower than those at 0.3–0.9 AU. The results from this work, taken together with measurements of SOHO/LASCO, EISCAT and MERLIN [Breen et al., 2002], Helios [Schwenn et al., 1978], and Ulysses [McComas et al., 2000], indicate that the fast wind is accelerated almost to its final flow velocity within 20 Rs and a small but not negligible acceleration exists beyond 30 Rs which tends to become smaller at farther heliocentric distances.

Since Hewish et al. (1964) discovered the interplanetary scintillation (IPS) phenomena, the IPS method has been used as one of the few devices which can be used to observe solar wind in three-dimensional space. However because of the line-of-sight integration effect of IPS, solar wind had to be studied with blurred images. In the late 1990s new methods of IPS observation and analysis which can deconvolve the line-of-sight integration effect were developed independently by a group at University California at San Diego (Grall et al., 1996) and a group at the Solar-Terrestrial Environment Laboratory, Nagoya University (Asai et al., 1998; Kojima et al., 1998; Jackson et al., 1998) . Today we can obtain unbiased solar wind images with high spatial resolution from IPS observations. The Ulysses spacecraft has been observing detailed structures of solar wind in three dimensions since its launch in 1990. However, Ulysses takes ten months even to make a rapid latitudinal scan from the south to north poles. IPS measurements have several advantages in comparison with spacecraft measurements. It can observe three-dimensional solar wind in a short time, and the observations can be carried out consistently over a solar cycle. Making use of these advantages of IPS, we have been studying several interesting solar wind features observed by Ulysses; namely, whether they are stable structures and how they depend on the solar cycle. We introduce these studies and propose a model to determine the solar wind velocity structure.

The ultrastructure of Trichophyton mentagrophytes cells stained with neutral red was investigated using electron microscopy and X-ray microanalysis. Fixatives containing molybdenum and chromium were used to prevent the outflow of neutral red. Electron-dense particles composed of metals and dye were observed exclusively in the vacuoles, which were increased in number and size, but not near the cell wall. Results indicate that neutral red passes directly through the fungal cell wall and is incorporated into the vacuoles.

In conventional vector quantization (VQ) method, the reachable best PSNR is implemented by full search or its equivalent method when the codebook is fixed. To achieve an even higher PSNR by fixed codebook, a post-processing VQ method is proposed . This method firstly checks how well the VQ matching is for a whole image and locates some bad matching image blocks definitely. Then it partitions a bad matching image block into two partial blocks further by a certain pattern and encodes them once again using the same fixed codebook but two different codes partially. It makes total distortion for current bad matching image block smaller. At the receiving end, the current bad matching image block is synthesized by two codes partially according to the adopted partitioning pattern so as to realize a better representation. For 10 gray-level standard images of size 512/spl times/512 with different detail, a 0.3 dB 1.2 dB PSNR improvement can be reached individually by just partitioning 5% worst matching image blocks at the cost of less than 1 bit degradation of equivalent code length. Moreover this improvement is basically for the edge portion of an image. Therefore, subject assessment can be made much better at the same time.

It is demonstrated that the dependence of the reverse breakdown voltage (V/sub B/) on the ambient temperature (T) of modern shallow and ultra-shallow Si pn junctions, required for future ULSI scaled down devices, is drastically changed, with respect to that of the deeper, conventional Si pn junctions reported so far. In this work it is shown that unlike the conventional junctions in which the dV/sub B//dT sign was determined by the dopant concentrations, in the present ultrashallow Si junctions, dVB/dT cm have positive, negative and zero slopes, in the same junction, almost independent of the dopant concentration.

[1] The heliospheric tomography of the interplanetary scintillation (IPS) showed that low-speed (≤350 km s−1) solar wind reappeared at the polar regions during the solar activity maximum of cycle 23. Comparing the distribution of solar wind velocity with the computed coronal magnetic structures, we found that the polar-low speed streams at the north polar regions appeared just before the polar open fields were about to disappear. The actual existence of the calculated polar open fields was confirmed in the coronal hole maps from the He I 10830 A absorption line, 195 A Fe XII emission line, and white-light images. This situation is very similar to the polar low-speed streams observed at the previous solar activity maximum of cycle 22.

Textures, textural transformation, and formation and annihilation of a single vortex were investigated in narrow cylinders with 100 microm radius in A-phase under rotation up to 6.28 rad/sec. Three textures were found, depending on the cooling conditions of the sample through the superfluid transition temperature T(c). We found the gyromagnetic effect of textures; that is, two textures (A or B) could be selected either by applying a magnetic field in parallel or anti-parallel to the rotation axis. The critical angular speed of a single vortex formation Omega(f) and that of annihilation Omega(a) for each texture were measured. The textural transformation in type A texture was induced by rotation. Both type A and B textures held macroscopic angular momentum along the rotation axis. We identified the texture for type A, B, and C as Mermin-Ho, radial disgyration, and a soliton type of defect along the axis, respectively.

The interplanetary scintillation (IPS) method can observe the dynamics and structure of the solar wind in three dimensions with a relatively short time cadence ( in situ measurements, we have been conducting multi-station 327 MHz IPS observations at the Solar-Terrestrial Environment Laboratory. The IPS measurement is a line-of-sight integration which is a convolution of the solar wind structures, the distance of these from the Earth and other diffraction effects present along the line of sight. We have recently succeeded in developing a method to deconvolve the line-of-sight integration effects using a computer-assisted-tomography (CAT) technique to obtain solar wind speed and electron density fluctuations. The CAT analysis not only retrieves three-dimensional solar wind parameters, but also provides better spatial resolutions than previous analysis techniques. The present IPS system at STELab observes several tens of IPS sources a day. To make solar wind observations with higher spatial and temporal resolution using the CAT method, we need more perspective views of the solar wind. Therefore, we are planning a new UHF antenna with an effective collecting area of 5500m^2 that will observe more than 100 IPS sources per day. The antenna is designed with a tolerance for radio noise interference and high aperture efficiency. Based on the successful development of the IPS CAT analysis, we are presently continuing a US-Japan cooperative project for space weather research between UCSD/CASS and STELab. This project with the new antenna will enhance IPS/US cooperation including future comparative analyses of data from the Solar Mass Ejection Imager (SMEI) and from STEREO.