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A high power density and a long pulse negative ion beam accelerator has been developed in QST to realize the ITER neutral beam accelerator. A main target was the H− ion beam acceleration up to 1 MeV with 200 A/m2 for 60 s. After the achievement of 1 MeV at a short pulse, the pulse length has been gradually extended by modifications of grid configurations to suppress grid heat loads due to negative ions and electrons. However, the beam energy was limited up to 0.7 MeV at 60 s operation. One issue was an unstable negative ion production for a long time due to arcing and excess temperature rise of a plasma grid for optimum negative ion production. To suppress arcing, a cathode filament shape was modified. The plasma grid was modified to have a large heat capacitance in order to suppress temperature rise for 60 s operation at high discharge power required for 1 MeV operation. Another issue is to optimize beam optics more precisely. Fine tuning of the 1st acceleration stage was carried to improve beam optics f...

The optical propagation property of a planar waveguide with a periodic nanoparticle grating layer is characterized by using sliding prism method. Here, Cu nanoparticle grating was fabricated on a-SiO 2 substrate by periodic heavy-ion irradiation technique. The pitch of these gratings was 2 μm and 3 μm, respectively. The flux and fluence were at the range of 6–10 μA/cm 2 and 6 × 10 16 –1 × 10 17 ions/cm 2 , respectively. The grating effect, mainly including the mode selection effect, is observed. The effect depends on the pitch of the grating and the morphology of nanoparticles. The propagation loss of the waveguide induced by nanoparticle layer is evaluated.

症例1は44歳女性．人間ドックにて肝腫瘍を指摘され，精査目的に入院．HBV, HCVなどウイルスマーカー陰性で肝機能異常は認めず，各種画像診断から肝血管筋脂肪腫（AML）を考え，経皮的腫瘍生検にて診断確定した．経過観察中にて腫瘍径の増大は認めていない．症例2は40歳女性．健診にて肝腫瘍を指摘され，各種画像診断でも肝細胞癌が否定できず，短期間に腫瘍径が増大したため左葉外側切除術を施行した．病理組織より肝血管筋脂肪腫と診断された．症例1, 2は最終診断では肝血管筋脂肪腫であったが，症例1では脂肪成分に富み典型的なAML所見であったのに対し，症例2は脂肪成分に乏しく診断困難であった．両者ともに肝静脈が流出血管として描出され，造影超音波検査が有用であった．

A precise grating profile evaluation method for distributed-feedback (DFB) laser diodes was achieved using a simple optical metrology. Spectroscopic scatterometry, an optical-wavelength light-diffraction technique, is emerging as a fast, accurate, and nondestructive means of monitoring profiles. A photoresist grating pattern on an InP substrate and an etched InP grating with periods of 0.2 and 0.24 mum were successfully evaluated by using unpolarized simple optical metrology. A precise grating profile evaluation technique with an accuracy of nanometers enabled us to obtain an accurate coupling coefficient (kappaL) for DFB laser diodes. DFB laser diodes with well-controlled kappaL are very promising for practical use in cost-effective optical networks.

This study investigated the molecular and pharmacokinetic mechanisms of the enhanced antiviral efficacy associated with pegylated interferon (PEG-IFN) alpha-2b and ribavirin. The study involved comparing the expression of serial double-stranded RNA-activated protein kinase (PKR) before and during treatment in 26 PEG-IFN alpha-2b and 26 conventional IFN alpha-2b recipients matched for age, body weight and dose of ribavirin. The pharmacokinetics of PEG-IFN alpha-2b and ribavirin was analysed in 15 of the 26 PEG-IFN recipients. There was a rapid increase in PKR expression in both treatment groups, although expression from day 2 onwards was maintained at a significantly higher level in the PEG-IFN recipients (P < 0.05). C(max) of PEG-IFN occurred 12-48 h after the initial administration, with t(1/2) and C(min) being 49 h and 190 pg/mL, respectively. In contrast to ribavirin, accumulation of PEG-IFN was minimal. There was no association between serum PEG-IFN and ribavirin levels and virological response. Although baseline expression of PKR before treatment was marginally higher in nonresponders (NRs), from day 2 onwards, sequential PKR expression in response to PEG-IFN was higher in sustained viral responders compared with the NRs (P < 0.05). Significant correlations were found between kinetics of PKR expression and viral decline rates in each phase of hepatitis C virus dynamics (first phase, r = 0.67, P = 0.0006; second phase, r = 0.67, P = 0.001). In conclusion, improvement in pharmacokinetics following pegylation led to higher intracellular PKR expression, which was associated with enhanced virological efficacy of PEG-IFN-based combination therapy. The concentrations of both ribavirin and PEG-IFN alpha-2b were not associated with viral response and PKR expression.

Optical properties of Au nanoparticle composites and a grid structure of Cu nanoparticle composite were studied. Negative ion implantation was applied to synthesize Au and Cu nanoparticles in amorphous SiO2 and Al2O3. Au nanoparticles were embedded within a depth of 30 nm by 60keV Au− implantation. The surface plasmon resonance (SPR) of Au:SiO2 and Au: Al2O3 composites shifted to red and to blue, respectively, compared to calculated ones by the Mie theory. Optical nonlinearity was measured with pump-probe femtosecond spectroscopy and the transient spectrum of Au: Al2O3 composite presented a large red shift from the SPR peak. Image mapping of far-field transmitted intensity of Cu-implanted SiO2 with a fine grid structure drawn by laser-lithography was observed by a scanning near-field optical microscopy (SNOM) system.

The injection performance of the negative-ion based NBI (N-NBI) system for JT-60U has been improved by correcting beamlet deflection and improving spatial uniformity of negative ion production. Beamlet deflection at the peripheral region of the grid segment due to the distorted electric field at the bottom of the extractor has been observed. This was corrected by modifying the surface geometry at the extractor to form a flat electric field. Moreover, beamlet deflection due to beamlet–beamlet repulsion caused by space charge was also compensated for by extruding the edge of the bottom extractor. This resulted in a reduction of the heat loading on the NBI port limiter. As a result of the improvement above, continuous injection of a 2.6 MW H0 beam at 355 keV has been achieved for 10 s. Thus, long pulse injection up to the nominal pulse duration of JT-60U was demonstrated. This has opened up the prospect of long pulse operation of the negative-ion based NBI system for a steady-state tokamak reactor. So far, a maximum injection power of 5.8 MW at 400 keV, with a deuterium beam, and 6.2 MW at 381 keV, with a hydrogen beam, have been achieved in the JT-60U N-NBI. Uniformity of negative ion production was improved by tuning the filament emission current so as to direct more arc power into the region where less negative ion current was extracted.

Objective The objective of this paper is to identify predictors for the response to treatment of acute lupus hemophagocytic syndrome (ALHS). Methods We reviewed seven cases with ALHS admitted to our hospital and published ALHS cases identified in the 2001–2014 Medline database, and then conducted univariate and multivariate analyses to identify predictors for the response to treatment. Results Review of our cases showed a significant and negative correlation between serum ferritin and anti-DNA antibody ( p = 0.0025). All three patients treated with cyclosporine A (CsA) were considered responders despite high serum ferritin and corticosteroid resistance. We also reviewed 93 patients with ALHS identified in 46 articles. Multiple logistic regression analysis identified C-reactive protein (CRP) (OR 0.83, p = 0.042) and hemoglobin (OR 1.53, p = 0.026) measured at diagnosis of ALHS as significant predictors of the response to corticosteroid monotherapy. Moreover, among 32 patients treated with CsA, serum ferritin was significantly higher in CsA responders (12163 ± 16864 µg/l, n = 22) than in non-responders (3456 ± 6267/µg/l, p = 0.020, n = 10). Leukocyte count was significantly lower in the CsA responders (1940.0 ± 972.3/µl) than in the non-responders (3253 ± 2198/µl, p = 0.034). Conclusion Low CRP and high hemoglobin can predict a positive response to corticosteroid monotherapy while high serum ferritin and low leukocyte count can predict a positive response to CsA in patients with ALHS and therefore, when corticosteroid monotherapy is not effective in such cases, CsA could be the first choice of an additional immunosuppressive agent.

The several hundred keV neutral beamline which is now operating on JT-60U marks the first usage of negative ion sources to produce high power neutral beams. Because this was such a large advance in the state of the art with respect to all system parameters, many new physical processes appeared during the earlier phases of the beam injection experiments. The physical mechanisms responsible for these processes have been explored, and solutions have been implemented for some of them, in particular excessive beam stripping, the secular dependence of the arc and beam parameters, and the non-uniformity of the plasma illuminating the beam extraction grid. This has reduced the percentage of beam heat loading on the downstream grids by roughly a third and has permitted longer beam pulses at higher powers. Progress is being made in improving the negative ion current density and in coping with the sensitivity of the caesium in the ion sources to oxidation by tiny air or water leaks, and the cathode operation is being altered.

Development for enhancing the beam characteristics in the N-NBI system for JT-60U has been continued since 1996. In order to increase beam power and duration time, a few countermeasures for improvement of source plasma non-uniformity have been tried. The first is changing arc current limiting resistors for changing arc current distribution, the second is regulating filament temperature for altering arc discharge mode, the third is optimizing a magnetic barrier in arc chamber, and the fourth is blocking the beam acceleration at a strongly non-uniform source plasma area by masking both upper and lower edge of plasma grid. All of these countermeasures have been confirmed to be effective.

The positive-ion based NB1 system for JT-60 began operation in 1986 with hydrogen beam, and had injected the neutral beam power of 27 MW at 75 keV. The beam species has been changed to deuterium through changing the ion sources and beam-line components in 1991. The NBI has injected a deuterium beam of 40 MW at 96 keV in 1996. In 2000, the computer control system for the beam operation has been changed from a mini-computer to a workstation system in order to match a great variety of beam injection parameters, and the operation capability has greatly improved.

This article describes a suitable network architecture for the mobile communications system beyond IMT-2000. The rapid developments in mobile communication services have significantly altered the lifestyles of many people. With the increasing demand for access to the Internet, the amount of data traffic in mobile communication networks has significantly increased and will dominate these networks. Therefore, mobile networks beyond IMT-2000 should offer higher bit rate channels and adapt to multimedia traffic more efficiently. This article first forecasts market trends in mobile communications in order to identify requirements of the mobile communications system beyond IMT-2000. Then the article considers the network architecture of the mobile communications system beyond IMT-2000 that will satisfy those requirements.

Optical properties of negative Cu ion-implanted silica glasses were measured over a photon energy range 0.5–6.5 eV. The implantation was conducted at high beam fluxes of 60 keV energy up to a total fluence of 3.0 × 1016 ions/cm2. From the transmission and reflection data, dielectric constants, eeff for the Cu implanted layer and em for the Cu nanoparticles, were self-consistently determined. In the dielectric spectra, bands due to the Cu particles were evidently present below 4.2 eV. An absorption band of the irradiated silica screened that of the Cu particles in the higher photon region. In the imaginary em spectrum, the intraband contribution disappeared owing to the nano-size effect and the interband contribution at 3.8 eV became smaller than that of bulk Cu. Third-order susceptibility χm(3) was also evaluated with the degenerate four-wave mixing and was of the order of 10−8–10−9 esu.

Head-attached interface device (HIDE) has been developed as a new type of human interface device in an actual work environment. The HIDE has flexible integrated functions which consist of speech recognition and view direction detection as hand-free input channels, direct presentation of audio/visual information as output channels, and mobile system configuration. In this paper, the design concept of the HIDE was first introduced, and individual functions to configure the design concept were developed by their separate testing. An integrated prototype system HIDE was then produced, and its functional evaluation test was made to examine the individual functions as the whole system. It was confirmed that the HIDE would be feasible enough to introduce in practical use.

Since code-division multiple-access (CDMA) capacity is interference limited, call admission control (CAC) must guarantee both a grade of service (GoS), i.e., the blocking rate, and a quality of service (QoS), i.e., the loss probability of communication quality. This paper describes the development of a new capacity design method based on these two concepts. Theoretical expressions for GoS and QoS as functions of traffic intensity and CAC thresholds are first derived from the traffic theory viewpoint, and then a design method using these expressions is presented. At that time, two strategies for CAC are assumed. One is based on the number of users, and the other is based on the interference level. Computer simulation results are presented that strongly support the proposed design method. Furthermore, numerical examples and a performance comparison of the two strategies considering various propagation parameters, nonuniform traffic distributions, and various transmission rates are shown.

The authors developed an automated 6-row rice transplanter. It has RTKGPS to locate precise position, FOG sensors to measures direction and actuators to control steering, engine throttle, clutch, brake and so on. RTKGPS has 3cm precision at 10Hz data output rate and FOG sensors are issued to restore the inclination of the vehicle. Main computer synchronizes RTKGPS position data with FOG data then it corrects the position error caused by the vehicle inclination. All actuators are controlled by a programmable logic controller (PLC). All control data is sent form main computer to PLC through RS232C. The drift of the FOG sensor was corrected by the using position data. To eliminate the influence of the drift, first, the deviation from the desired path calculated by the yaw angle and vehicle speed was compared with the deviation calculated by GPS data. Then the drift of the heading angle was calculated. The influence of the FOG drift can be eliminated, the authors can correct the FOG drift and the initial error of heading angle and can make long time operation continuously. The experiment was conducted 4 days after puddling. The deviation from the desired straight path was less than 10cm at 0.8m/s of travel velocity. During the rice transplanter went forward and back in a 30m*100m square field 5 times, we obtained satisfactory results.

Acceleration of a 500 keV beam up to 2.8 A has been achieved on a JT‐60U negative ion source with a three‐stage accelerator by overcoming low voltage holding which is one of the critical issues for realization of the JT‐60SA ion source. In order to improve the voltage holding, preliminary voltage holding tests with small‐size grids with uniform and locally intense electric fields were carried out, and suggested that the voltage holding was degraded by both the size and local electric field effects. Therefore, the local electric field was reduced by tuning gap lengths between the large size grids and grid support structures of the accelerator. Moreover, a beam radiation shield which limited extension of the minimum gap length was also optimized so as to reduce the local electric field while maintaining the shielding effect. These modifications were based on the experiment results, and significantly increased the voltage holding from

Excess heat loads to accelerator grids limit extension of pulse length in operation of the large negative ion sources with multi aperture accelerator. Part of the heat loads is caused by interception of deflected beamlets due to their space charge repulsion. In this paper, a beamlet steering technique using aperture offset was examined for compensation of the beamlet deflections utilizing a three dimensional beam analysis simulating the D− negative ion source of JT‐60 U. The beamlet deflection was analyzed in detail using fifty beamlets, which were extracted from apertures arranged in a lattice pattern of 10×5. The simulation showed successful compensation of the beamlet deflection by aperture offsets defined according to the thin lens theory. Even if the beam energy was changed, the necessary aperture offset would not be changed maintaining the perveance and a ratio of extraction and acceleration voltage. In JT‐60 U, it was shown that the aperture offset of less than 1.0 mm would be enough to compensate ...

The occurrence of antibodies against recombinant human interferon-alpha 2a (IFN-alpha 2a) in patients with acute viral hepatitis (AVH) was examined by ELISA. Naturally occurring IgG anti-IFN-alpha 2a were found in 50% of patients with type A, 50% of those with type B and in 8.3% of those with non-A, non-B AVH. The corresponding frequencies of IgM antibodies were 80%, 30% and 33.3%, respectively. IgM anti-IFN-alpha 2a were found more frequently in patients with AVH type A than in normal control subjects (P less than 0.01). Anti-IFN-alpha 2a were detectable at the highest frequency 3 weeks after acute onset and then became negative. An absorption experiment revealed that IgM anti-IFN-alpha 2a did not cross-react with recombinant human IFN-alpha 2b. Immunoblotting analysis confirmed the binding of antibodies to IFN-alpha 2a. Sera positive for IgG and/or IgM anti-IFN-alpha 2a were unable to neutralize IFN-alpha 2a. The appearance of anti-IFN-alpha 2a was not correlated with disease severity. There was no evidence to suggest that anti-IFN-alpha 2a impaired the elimination of hepatitis virus. This is the first study to demonstrate the occurrence of anti-IFN-alpha 2a in patients with AVH. Detection of anti-IFN-alpha 2a may be useful for clarifying any underlying immune events in various diseases.

Background/Aims Interferon (IFN) therapy leads to regression of hepatic fibrosis in chronic hepatitis C patients who achieve a sustained virologic response (SVR), while the beneficial effect is limited in those who fail to do so. The aim of the present study was to define factors associated with progression of fibrosis in patients who do not achieve a SVR. Methods Fibrosis staging scores were compared between paired liver biopsies before and after IFN in 97 chronic hepatitis C patients who failed therapy. The mean interval between biopsies was 5.9 years. Factors associated with progression of fibrosis were analyzed. Results Fibrosis progressed in 23%, remained unchanged in 47% and regressed in 29%. Steatosis and a high average alanine aminotransferase (ALT) between biopsies were independent factors for progression of fibrosis with risk ratios of 5.53 and 4.48, respectively. Incidence and yearly rate of progression of fibrosis was 64% and 0.22±0.29 fibrosis units per year in those with both risk factors compared to 8% and −0.04±0.17 fibrosis units per year in those negative for both factors. Conclusions Hepatic steatosis and elevated ALT levels are risk factors for progression of fibrosis in chronic hepatitis C patients who fail to achieve a SVR to IFN therapy and therefore may be therapeutic targets to halt the potentially progressive disease.

This paper reports on the development of compact surface plasmon resonance (SPR) sensors to be used for mobile robot olfaction. The proposed sensor uses a periodic metal structure formed on top of the self-assembled layer of polystyrene particles of 200 nm in diameter. With the grating of this size, SPR can be excited even with an LED light source. The change in the absorbance is simply measured using a photodiode. The experimental results are presented on a silver nanostructure sensor and a gold nanostructure sensor to show the potential of these sensors.

In order to satisfy the expectation of the users to have more advanced wireless access even in the mobile environments, research and development efforts for realizing the fourth-generation (4G) mobile communication system has been discussed. This paper outlines the requirements for the system, technical challenges to be solved, and finally describes the activities related to the standardization of the 4G mobile communication system

The pulse duration of the negative ion based NBI system has been extended from 10 s to 25 s to study long pulse plasmas on JT-60U. A feedback control technique has been demonstrated to keep the arc power constant by controlling the filament voltage for long pulse operation. Thus it was clearly observed that the negative ion beam current increased with the temperature of the plasma grid at constant arc power. A tapered filament is employed to improve its durability for the next operational campaign. Moreover, a high voltage holding test indicates that the reduction in the outgassing from the FRP (fiberglass-reinforced plastic) insulator may be a key to suppress the breakdowns in the ion source

Demand for mobile ad hoc networks (MANET) is increasing. In a MANET, mobile stations communicate with each other by autonomous distributed control. Although flooding is used for discovering a route from a source to a destination, there is the broadcast storm problem when traffic increases rapidly. Besides, there is the hidden terminal problem that packet collisions may be caused in wireless communication. For solving these problems, we propose M-DSMA (MAC protocol using dynamic state transition of mobile stations in ad hoc networks). We define two kinds of states (active state and non-active state) at the mobile station. During the active state, a busy tone is sent as the active state station detects that the channel is busy, and a stop tone is sent as the active state station detects packet collisions. By using two tones, the reachability can be improved.

Broadband CDMA packet access is one of the most promising air interfaces for future 4G mobile communication systems. In this study, a novel reservation-based access protocol with prioritized resource allocation (PRA) is proposed as a reverse channel MAC protocol, which enables various rate real-time communications on such a system. In this protocol, a low-rate temporal dedicated control channel (TDCCH) is momentarily assigned between a base station (BS) and mobile station (MS). A TDCCH is used to transmit not only access control signals including a reservation signal, but also transmission control signals such as transmission power control (TPC) commands. This protocol prevents a packet-by-packet setup delay and provides contention-free packet reservation so long as a TDCCH is established. The duration of the TDCCH can be controlled according to the quality of service (QoS) requirement. PRA is based on such a reservation scheme, and two different resource allocation areas are defined in time slots that correspond to real-time and best-effort classes. The real-time packets have a wider allocation area so that they can acquire radio resources prior to best-effort packets. Thus, resources are assigned to real-time packets first, and the remaining resources can be used for best-effort packet transmission. By combining admission control and flow control with PRA, real-time packet communication can be achieved in the reverse channel. The performance of the proposed protocol is evaluated by computer simulation and through an experimental system.

A novel wireless QoS architecture suitable for broadband CDMA packet cellular systems is proposed and its characteristics are described. The proposed QoS architecture is composed of several control factors laid on MAC and RRC layers, and can be harmonized with IP-QoS. Two important control factors, i.e., radio condition aware admission control and resource allocation reflected hybrid scheduling, are proposed. Computer simulations and testbed experiments indicate that by using radio condition aware admission control, stable and guaranteed service can be provided to realtime users regardless of interference and location variation of the mobile station. Moreover, resource allocation reflected hybrid scheduling maintains guaranteed rates for realtime users and provides high resource utilization efficiency for best effort users. Consequently, by using the proposed wireless QoS architecture, it is possible to provide users with high quality and diversified realtime services, on a packet based radio network for 3.5G and 4G.

A multihop connection scheme, where one or more mobile terminals relay transmission signals using the same access scheme between an end user terminal and its destination base station, is a promising approach to overcome reduction in cell size caused by high bit-rate data transmission. In a general radio communication system, coverage area and system throughput are closely interrelated. In this paper, the performance of a multihop cellular network employing a CDMA access scheme, which is a promising candidate for beyond the third generation, is studied in terms of coverage area and system throughput by conducting a link level simulation. The results show that a multihop connection expands a coverage area, especially in a light traffic case, and also has an advantage in system throughput.

In the operation of hierarchical mobile IPv6 (HMIP) (H. Soliman, et al., 2003), a mobile node (MN) is supposed to send binding updates (BUs) to the home agent (HA) and a mobility anchor point (MAP); therefore, a MAP discovery protocol is needed to facilitate MN discovery of MAPs. Two protocols were previously proposed in (H. Soliman, et al., 2003) for MAP discovery, however, in both protocols, all access routers (ARs) must issue router advertisements (RAs) with MAP information option fields in order for the MNs to receive them. In such MAP discovery protocols, ARs must be aware of HMIP operation for the advertising of MAP information. In this paper, we introduce a new MAP discovery protocol that is transparent to ARs. Such transparency would bring about wider applicability for HMIP than previously achieved, which is important from industrial and commercial viewpoints. In addition, we confirm that the proposed protocol meets the requirements, and we evaluate its performance by computer simulation.

Mobility support for mobile networks will be more important as the mobile Internet becomes increasingly popular. To support mobile networks, the concept of prefix scope binding (PSB) is being discussed in IETF; however, by only applying this concept to Mobile IPv6 (MIP), the problem of packet loss still remains. In this paper, we apply the PSB concept to our proposed protocol, the hierarchical Mobile IPv6 extension with buffering function (HMIP-B), in which mobility anchor points buffer packets destined to the mobile hosts during handoff. We compare MIP and HMIP-B based on the handoff performance related to mobile networks by computer simulation. The simulation results indicate that our proposal improves the handoff performance in both TCP and UDP communications.

This paper proposes an adaptive battery conservation management (ABCM) method that controls the battery consumption without deteriorating the quality of service (QoS) in connection-less packet radio systems. The ABCM method has three states: active mode, idle mode, and battery saving mode (BSM). The BSM is a battery conservation state in which each mobile terminal (MT) awakens periodically to conserve its battery and to receive packet arrival notifications sent by a base station. In this method, a sleep-timer is predetermined and if no packet is transmitted or received within the duration of the sleep-timer, an NIT transits to the BSM. In addition, the sleep-timer and a paging interval are set according to the QoS classes of each packet. For the packets in the real-time class, a longer period is selected for the sleep-timer to refrain from entering the BSM. While in the non-real-time class, a shorter period is chosen for effective battery conservation. This paper evaluates the battery conservation effect by theoretical analysis and computer simulation. Numerical evaluations show that the ABCM method is suitable for connection-less packet radio systems. In the real-time class, the wake up delay is controlled by employing the ABCM even if it is done by connection-less packets. Meanwhile in the non-real-time class, an NIT exhibits more effective battery conservation than does the conventional method.

It is expected that as the integration proceeds between mobile communication systems and the Internet, the amount of data traffic will drastically increase in the IMT-2000 (3G) and beyond (4G) mobile communications systems. With the demand for high-speed mobile multimedia and that for supporting diverse user requirements, wireless QoS (quality of service) will play an important role and becomes a challenging issue, due to the dynamic fluctuating nature in wireless channel conditions and the limited availability of radio resources. Especially in the CDMA cellular system where radio resource is shared among cells, the dynamic fluctuating nature in the wireless channel may more-profoundly affect the user QoS. From these perspectives, this paper focuses on packet-scheduling aimed at utilizing radio resources efficiently while supporting user's QoS. Novel packet-scheduling schemes proposed here, STPD and STPD-SPF, cannot only utilize radio resource efficiently by considering required transmission power, but also support QoS of each user by monitoring buffering delay. Simulation results indicate that these schemes can improve traffic performance and QoS satisfaction rate.

The authors describe two methods to enhance the performance of digital mobile cellular systems. First, micro/macro overlay cell structures are proposed and investigated from the aspects of capacity and link control. Increased capacity is realized and control channel structures are detailed. Next, an effective channel assignment procedure is proposed and evaluated for a system overlay structure from the aspects of loss probability and control load. >

A high-efficiency common control channel structure for digital mobile radio systems is described. It is spectrum efficient and is suitable for providing a variety of services, such as ISDN (integrated services digital network) services. A layered signaling structure and call-control sequences using a layered protocol are presented. The common control channel structure for a digital mobile radio system is proposed. It can handle any traffic distribution and can realize economical base stations. >

A control channel structure for time-division multiple access (TDMA) mobile radio systems that must offer high system capacity and ISDN services is described. This structure overcomes the difficulties in random access efficiency and the application of a layered protocol. A functional channel definition and layered signaling frame format are described. Functional channel mapping on physical channels is then described. Several methods for the frequency assignment of control channels are compared from the points of radio channel efficiency and functional ability. The optimum method is determined. Mapping information is broadcast to realize the control channel structure needed. An improved random access scheme for the common control channel is proposed. This scheme obtains good throughput performance, and realizes the application of data link layer protocols. Thus, efficient and flexible signaling for radio link control and data services is achieved. >

Diversity handover (DHO), which can reduce the transmit power and interference through the site diversity effect, is essential for high capacity DS-CDMA cellular systems. System capacity depends on how diversity handover is applied. This paper describes reverse and forward link system capacity for several typical handover schemes under transmit power control (TPC) based on SIR as determined by computer simulations. First, both link system capacities are shown under perfect TPC. These results give an ideal upper limit of capacity. We examine the increase in system capacity achieved by maximal-ratio-combining (MRC) and sectorization. Next, we consider TPC error, which leads to more realistic capacity values. This shows that system capacity with DHO is larger than with hard handover (HHO) in both links. Especially with MRC-DHO in the forward link, there is an optimum threshold for DHO that maximizes the capacity.

Mobile IPv6 supports packet routing for hosts moving on the Internet, but lacks support for networks moving on the Internet. For example, a network comprising a set of hosts and routers in a train can be a mobile network. While the mobile network is moving, a router in the network changes its point of connection to the Internet. This paper proposes an architecture and Mobile IPv6 extensions that support packet routing for mobile networks. The proposed scheme enables any host on a mobile network to communicate with any host connected to the Internet.

This paper presents a system architecture for mobile communications systems beyond IMT-2000 (4G system). Considering the growth of data communications through mobile networks, the 4G system should offer higher bit rate channels and accommodate a significantly larger amount of traffic. To meet these requirements, the 4G system may use higher frequency bands. This paper first considers objectives of the 4G system and it proposes a system architecture that meets the objectives. The architecture proposed in this paper comprises core networks that will accommodate multiple types of radio access networks (RAN). The 4G RAN is constructed by distributed controlled base stations that are connected to each other by a multi-hop wireless network.

With the rapidly increasing demand for providing highspeed mobile multimedia and supporting diversified requirements of users, wireless quality of service (QoS) resource management becomes more and more indispensable, especially for the upcoming IMT-2000 system and beyond. In this paper, a wireless QoS architecture and two QoS resource allocation algorithms for CDMA cellular systems are proposed to meet these requirements. Based on the proposed QoS architecture, an adaptive QoS resource management is proposed to assign radio resource corresponding to its availability and the users' maximum and minimum QoS requirements. A service-rank-based QoS resource management is further proposed to satisfy more high-rank users as much as possible while maintaining the minimum requirement of low-rank users. Computer simulations indicate that the proposed QoS resource management algorithms exhibit superior performance with respect to dropping probability, rate of satisfied users and necessary transmission time, which indicate higher satisfaction rate of users and better performance.

In this paper, the authors consider a one-link robot arm, and the purpose of this study is to realize a frictionless joint of the arm of a robot. In order to do so, compensation of not only friction but also spring effect in harmonic gear which is set on the motor shaft is required. For their compensation, the authors consider a nonlinear sliding mode disturbance observer, and removing the effect of the disturbance by the observer, the parameters of the system are identified by a GA (genetic algorithm). The disturbance observer is also implemented in a controller in an online manner, so that frictionless jointing of the arm of the robot is realized. In order to verify the frictionless joint by compensation of the disturbance, the authors try to set the spring characteristics for the joint by a control design. The effectiveness of their proposal is verified by simulation and experimental results.

This paper proposes an agglomerating radio resource control method for wireless packet access systems that makes effective use of limited radio resources to provide users with their desired bandwidths. In the proposed method, each mobile station (MS) communicates with multiple base stations (BSs) simultaneously, and gathers from the neighboring BSs, as well as from the BS currently communicating with the MS, information about radio resources that have not been allocated to other MSs. The MS then sums up the bandwidths supported by the vacant resources, and if the total bandwidth is found to be larger than the MS's requirement, it keeps the connections with the multiple BSs to ensure communication continuity. This method is especially effective when traffic load is heavy in the cell hosting the mobile user. This paper evaluates the performance of the proposed method in various aspects such as throughput efficiency, resource allocation and successful packet transmission probabilities, as well as resource utilization ratio, under interference-limited environments.

The growth in mobile multimedia services will accelerate over the next decade. This paper discusses service aspects and system requirements for the fourth generation mobile communication (4G) system that will allow us to provide higher-speed communications and deal with user demand in the next decade. This paper also proposes a new radio access network (RAN) structure suited to the 4G system. The principles of the proposed cluster-cellular RAN are localized handover processing and horizontal structure. The advantages of the proposed RAN are also discussed.

High-energy ion implantation is one of the unique methods to fabricate nano-scale structures, taking advantage of the spatial controllability and the non-equilibrium atomic injection. Metal-ion implantation into a transparent insulator creates a metal nanoparticle composite, which is promising as a nonlinear optical material with ultrafast response. Radiation damage of substrates and/or nanoparticles, which is inherent in ion implantation, is a drawback for optical performance of the nanoparticle composites. It is desired to annihilate radiation damage without melting the matrix. We have applied laser irradiation of sub-gap energy during heavy-ion implantation. Copper ions of 3 MeV and laser of a sub-gap energy (2.3 eV) irradiated insulators of a-SiO2 and spinel MgO"2.4(Al2O3). The dose rate varied up to 10 (mu) A/cm2 for Cu ions of 3 MeV and up to 0.2 J/cm2"pulse at 10 Hz for YAG-SHG laser. Only when ions and photons were simultaneously irradiated at the higher photon intensity (> 0.1 J/cm2"pulse), the insulators were effectively bleached in the optical absorption spectra. As well as the bleaching, precipitation enhancement and atomic desorption took place. The results indicate importance of dynamical electronic excitation during ion irradiation and that the photon irradiation enhances atomic displacements either at the surface or in the bulk.© (2002) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

In this chapter, the following five topics are selected within various applications using near field optics. First, we describe the principle and equipment of the birefringent-contrast near-field optical microscope and observations of samples in Sect. 10.1 The observation of birefringent distribution is important in view of the evaluation of liquid crystal or polymer materials by molecular orientation. In Sect. 10.2, the development of a simple low-temperature near-field optical microscope is explained. Low-temperature near-field optical microscopes are necessary for semiconductor spectral analysis, e.g., quantum dot, because conventional microscopes are difficult to handle and change samples. In Sect. 10.3, a near-field microscope system is developed that can detect tunneling light emission from the probe tip of the scanning tunneling microscope. The feature of this microscope is observing the optical emission characteristic distribution of a sample with lateral resolution on the nanometer scale. In Sect. 10.4, a new method for detecting an evanecent wave is proposed that uses an electron beam as a probe; it has succeeded in observing an evanescent wave in the infrared region experimentally. In Sect. 10.5, we describe a method and features for driving Mie particles by an evanescent photon force formed in an optical channeled wave-guide. The driving performance of a multimode waveguide has been especially clarified.

Voltage holding capability of JT-60 negative ion source that has a large electrostatic negative ion accelerator with 45 cm x 1.1 m acceleration grids was experimentally examined and improved to realize 500 keV, 22 A, and 100 s D- ion beams for JT-60 Super Advanced. The gap lengths in the acceleration stages were extended to reduce electric fields in a gap between the large grids and at the corner of the support flanges from the original 4-5 to 3-4 kV/mm. As a result, the voltage holding capability without beam acceleration has been successfully improved from 400 to 500 kV. The pulse duration to hold 500 kV reached 40 s of the power supply limitation.