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ABSTRACT: Thick (>50μm) piezoelectric films have been deposited directly on top of steel and aluminum substrates as integrated ultrasonic
transducer (IUT) receivers to detect laser generated ultrasound. The film fabrication is based on a sol-gel spray technique.
In this study IUTs intrinsically acting as bulk longitudinal wave receivers use various mode conversion approaches and serve
as longitudinal, shear, symmetric, anti-symmetric and shear horizontal plate wave receivers. Different laser generation conditions
such as point and line sources of different sizes are also applied to investigate the capabilities of IUT receivers. Ultrasonic
measurements on metal substrates with planar and curved surfaces at temperature up to 400°C using laser generated and IUT
ultrasound receiver are demonstrated.
KeywordsIntegrated ultrasonic transducers–Laser ultrasound–High temperature–Longitudinal and shear waves–Plate acoustic waves–Non-destructive testing
Journal of Nondestructive Evaluation 04/2012; 30(1):1-8. · 1.17 Impact Factor
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S. Kobayashi,
N. Hasebe,
E. Shibamura,
O. Okudaira, M. Kobayashi,
N. Yamashita,
Y. Karouji,
M. Hareyama,
K. Hayatsu,
C. d’Uston,
S. Maurice,
O. Gasnault,
O. Forni,
B. Diez,
R. C. Reedy,
K. J. Kim
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ABSTRACT: The Kaguya gamma-ray spectrometer (KGRS) has great potential to precisely determine the absolute abundances of natural radioactive
elements K, Th and U on the lunar surface because of its excellent spectroscopic performance. In order to achieve the best
performance of the KGRS, it is important to know the spatial response function (SRF) that describes the directional sensitivity
of the KGRS. The SRF is derived by a series of Monte Carlo simulations of gamma-ray transport in the sensor of the KGRS using
the full-fledged simulation model of the KGRS, and is studied in detail. In this paper, the method for deriving absolute abundance
of natural radioactive elements based on the SRF is described for the analysis of KGRS data, which is also applicable to any
gamma-ray remote sensings. In the preliminary analysis of KGRS data, we determined the absolute abundances of K and Th on
the lunar surface without using any previous knowledge of chemical information gained from Apollo samples, lunar meteorites
and/or previous lunar remote sensings. The results are compared with the previous measurements and the difference and the
correspondence are discussed. Future detailed analysis of KGRS data will provide new and more precise maps of K, Th and U
on the lunar surface.
KeywordsMoon-SELENE (Kaguya)-Gamma-ray spectrometer-Spatial response function-Natural radioactive elements-K-Th-U
Space Science Reviews 04/2012; 154(1):193-218. · 3.61 Impact Factor
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ABSTRACT: We consider a practical scenario of the Gaussian multiantenna wiretap channel where a transmitter with no channel state information wishes to send a confidential message to its legitimate receiver in the presence of an eavesdropper. It has been known that the secrecy capacity of such a channel does not scale with signal-to-noise ratio under general conditions. Taking into account the different temporal fading structures at the legitimate receiver and the eavesdropper, we characterize lower and upper bounds on the secrecy degrees of freedom (s.d.o.f.) of the channel at hand. Our results show that a positive s.d.o.f. can be ensured whenever two receivers experience the asynchronous variation. Remarkably, simple linear precoding schemes provide the optimal s.d.o.f. in most cases of interest by aligning either the confidential signal at the eavesdropper or the artificial noise at the legitimate receiver.
IEEE Transactions on Information Forensics and Security 10/2011; · 1.34 Impact Factor
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ABSTRACT: The secrecy degrees of freedom (SDoF) of the Gaussian multiple-input and single-output (MISO) wiretap channel is studied under the assumption that delayed channel state information (CSI) is available at the transmitter and each receiver knows its own instantaneous channel. Such scenario is of practical interest since the legitimate receiver may send its channel states to the transmitter which is overheard by the eavesdropper. We first show that a strictly positive SDoF can be guaranteed whenever the transmitter has delayed CSI (either on the legitimate channel or/and the eavesdropper channel). In particular, in the case with delayed CSI on both channels, it is shown that the optimal SDoF is 2=3. We then generalize the result to the two-user Gaussian MISO broadcast channel with confidential messages and characterize the SDoF region when the transmitter has delayed CSI of both receivers. Interestingly, the artificial noise schemes are shown to provide the optimal SDoF region by masking the confidential message to the unintended receiver while aligning the interference at each receiver.
Information Theory Proceedings (ISIT), 2011 IEEE International Symposium on; 09/2011
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ABSTRACT: We consider a multicell frequency-selective fading uplink channel (network MIMO) from K single-antenna user terminals (UTs) to B cooperative base stations (BSs) with M antennas each. The BSs, assumed to be oblivious of the applied codebooks, forward compressed versions of their observations to a central station (CS) via capacity limited backhaul links. The CS jointly decodes the messages from all UTs. Since the BSs and the CS are assumed to have no prior channel state information (CSI), the channel needs to be estimated during its coherence time. Based on a lower bound of the ergodic mutual information, we determine the optimal fraction of the coherence time used for channel training, taking different path losses between the UTs and the BSs into account. We then study how the optimal training length is impacted by the backhaul capacity. Although our analytical results are based on a large system limit, we show by simulations that they provide very accurate approximations for even small system dimensions.
IEEE Transactions on Signal Processing 07/2011; · 2.63 Impact Factor
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ABSTRACT: We propose a technology for manipulating the position and orientation of an object in a contactless manner over an extended range. This technology involves multiple ejectors that stream jets of compressed air onto an object from various directions. By regulating the air jet directions and flow rates, the object can be actively "force closured" and its position and orientation can be manipulated freely. As the first step of this research, in this paper, we discuss technological challenges for this method. Next we provide a preliminary investigation with one degree-of-freedom planar experimental system using a continuous and a PWM air jet ejection method. Based on this investigation, we examine problems relating to the use of three air nozzles to control the position of a cylindrical object in two degrees of planar freedom.
Robotics and Automation (ICRA), 2011 IEEE International Conference on; 06/2011
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ABSTRACT: The damage detection capability of a flexible ultrasonic transducer (FUT) array bonded onto a planar and a curved surface are presented. The piezoelectric lead zirconate titanate composite (PZT-c) film FUT arrays are fabricated on a 75 m titanium membrane substrate using a sol-gel spray technique. The test article was a complex aluminium component that is representative of aircraft structural complexity. Room temperature curable adhesive is used as the bonding material and ultrasonic couplant between the FUT and the test article. The glue has been successfully tested in the temperature range of 80C to 100C, which covers the sensor operating temperatures commonly required for aircraft structures. For a planar surface, the selected FUT arrays were able to detect the fasteners and the 2.54 mm-long electrical discharge machining (EDM) notch up to a distance of 176 mm with sufficient signal-to-noise ratio. The pulse-echo measurements obtained by the FUT array were compared with those of a commercial 10 MHz ultrasonic transducer (UT). The results showed that the performance of the FUT array was as good as the commercial UT. Another FUT array was bonded onto a curved surface of the test article using the same adhesive. No measurement using commercial UTs was taken on the curved surface because restricted access around this area did not allow such measurement. The pulse-echo measurements confirmed the detection of EDM notches of 2.54 mm and 1.27 mm in length. The experimental results demonstrated the potential of FUT arrays for aircraft structural health monitoring.
Insight - Non-Destructive Testing and Condition Monitoring 05/2011; 53(6):316-320. · 0.57 Impact Factor
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H. Saitoh,
Z. Yoshida,
J. Morikawa,
Y. Yano,
T. Mizushima,
Y. Ogawa,
M. Furukawa,
Y. Kawai,
K. Harima,
Y. Kawazura,
Y. Kaneko,
K. Tadachi,
S. Emoto, M. Kobayashi,
T. Sugiura,
G. Vogel
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ABSTRACT: High-β ECH plasma is generated and stably sustained in a magnetospheric configuration, the Ring Trap 1 (RT-1) device, generated by a levitated dipole field magnet. Geomagnetic-field compensation and optimized operation have realized drastic improvements in plasma properties. The maximum local β value has reached 70% and the pressure profiles have a rather steep gradient near the superconducting magnet. Electrons of the high-β plasma typically consist of 70% hot (~50 keV) and the rest of cold populations. Confinement time of the hot component plasma is 0.5 s with the optimized neutral gas pressure. By removing the coil support structure, the peaked density profile is observed in the strong field region.
Nuclear Fusion 05/2011; 51(6):063034. · 4.09 Impact Factor
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Physics of Plasmas 04/2011; 18(5):056102-056102-9. · 2.15 Impact Factor
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ABSTRACT: The exponentially increasing demand for wireless data services requires a massive network densification that is neither economically nor ecologically viable with the current cellular system architectures. A promising solution to this problem is the concept of small-cell networks (SCNs), which is founded by the idea of a very dense deployment of self-organizing, low-cost, low-power, base stations (BSs). Although SCNs have the potential to significantly increase the capacity of cellular networks while reducing their energy consumption, they pose many new challenges to the optimal system design. We show in this article how a large system analysis based on random matrix theory (RMT) can provide tight and tractable approximations of key performance measures of SCNs.
IEEE Vehicular Technology Magazine 04/2011; · 1.23 Impact Factor
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ABSTRACT: Ge is one of the promising candidates for high-mobility channel material in future complementary metal-oxide-semiconductor technology. High-field transport in short-channel Ge p-channel field-effect transistors (PFETs) needs to be examined since device performance is determined by high-field velocity in quasi-ballistic transport regime. In this paper, ballisticity and the relationship between carrier velocity and mobility in short-channel (70-nm) Ge PFETs were thoroughly investigated. A 1.6 × -2× higher velocity was confirmed in Ge PFETs than that in Si PFETs. Uniaxial stress is also a strong performance booster besides high-mobility substrate. The effectiveness of the uniaxial stress to velocity enhancement in Ge PFETs was experimentally demonstrated in short channel regime. A 1.4× higher drive current can be achievable by uniaxially strained Ge PFET in ballistic transport regime as compared with strained Si PFET.
IEEE Transactions on Electron Devices 03/2011; · 2.32 Impact Factor
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ABSTRACT: We propose a new gesture interface based on unicursal figures for TV control via touch-screen personal devices. The interface is a powerful but simple way of accessing the multiple functions of modern TVs. Unicursal figures are made without lifting the thumb from the screen and sequences of commands can be issued without needing to confirm the thumb's position. Trial use confirms the feasibility of this interface.
Consumer Electronics (ICCE), 2011 IEEE International Conference on; 02/2011
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ABSTRACT: The chain dimensions of free and immobilized polysulfobetaine in aqueous solution at various salt concentrations were investigated by size-exclusion chromatography with multiangle light scattering and neutron reflectivity measurement, respectively. The dependence of the z-average mean square radius of gyration ( z1/2) on the weight-average molecular weight (Mw) of free poly(3-(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfo-nate) (MAPS) in aqueous solution at salt concentrations of 74, 100, 200, and 500 mM was described by the perturbed wormlike chain model using the chain stiffness parameter λ−1 the molar mass per unit contour length ML, and the excluded volume effect B. B increased from 0 to 1.8 nm with increasing salt concentration to 500 mM due to the screening of attractive electrostatic interaction between ammonium cations and sulfonyl anions by salt ions. The swollen structure of the poly(MAPS) brush in D2O changed from a shrunken state to a relatively extended state with increasing salt concentration from 0 to 500 mM NaCl/D2O solution. The thickness of the swollen poly(MAPS) brush in 500 mM NaCl/D2O was 9.0 times greater than 2 z1/2 of free poly(MAPS) due to high osmotic pressure generated by the excluded volume effect of densely grafted polymer chains.
Journal of Physics Conference Series 02/2011; 272(1):012010.
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S. Koike,
S. Asakawa, M. Kobayashi,
R. Nagase,
J. Kobayashi,
K. Uesugi,
K. Kajiwara,
A. Takeuchi,
Y. Suzuki,
I. Hirosawa,
Y. Watanabe
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ABSTRACT: Laser fusion splicing has been realized for the simple splicing of optical fibers in a small board area, and for accommodating the increasing number of optical fibers that must be mounted on a board. For the splicing, zirconia ceramics are conventionally used to fabricate V-groove substrates because of their high machining performance. In this study, the existence of zirconium inclusions between the spliced optical fibers could be clarified with SPring-8 micro-computed tomography (SP-μCT) for the first time. The large inclusion size was found to increase the splicing loss. Moreover, the average splicing loss could be reduced from 0.18 dB to 0.15 dB by the adoption of a cleaning process to remove the zirconium inclusions that originate from the V-groove substrate used for the fiber.
IEEE Transactions on Components, Packaging, and Manufacturing Technology 02/2011; · 0.98 Impact Factor
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ABSTRACT: In this study, the effects of chelating ligands on iron movement in growth medium, iron bioavailability, and growth of radish sprouts (Raphanus sativus) were investigated. Iron is an important nutrient for plant growth, yet the insoluble state of iron hydroxides in alkaline conditions decreases its bioavailability. Iron chelates increase iron uptake and have been used in agriculture to correct iron chlorosis. While previous studies have reported the effects of chelating ligands on iron solubility and bioavailability, the present study elucidates the pattern of iron movement by chelating ligands in plant growth medium. The apparent mobility of iron in growth medium was calculated using a [`]4-box' model. Ethylenediaminedisuccinic acid (EDDS) and hydroxy-iminodisuccinic acid (HIDS) produced the highest apparent mobility of iron from the bottom layer of the medium (initially 10-4 M Fe(III)) to the upper layer (no iron), followed by glutamatediacetic acid (GLDA), ethylenediaminetetraacetic acid (EDTA), methylglycinediacetic acid (MGDA), and iminodisuccinic acid (IDS). Iron movement in the growth medium was influenced by the chelating ligand species, pH, and ligand exposure time. The iron uptake and growth of radish sprouts were related to the iron mobility produced by the chelating ligands. These results suggest that, in alkaline media, chelating ligands dissolve the hardly soluble iron hydroxide species, thus increasing iron mobility, iron uptake, and plant growth. HIDS, which is biodegradable, was one of the most effective ligands studied; therefore, this compound would be a good alternative to other environmentally persistent chelating ligands.
Environmental and Experimental Botany 01/2011; 71(3):345--351. · 2.98 Impact Factor
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ABSTRACT: journal published by Elsevier. The attached copy is furnished to the author for internal non-commercial research and education use, including for instruction at the authors institution and sharing with colleagues. Other uses, including reproduction and distribution, or selling or licensing copies, or posting to personal, institutional or third party websites are prohibited. In most cases authors are permitted to post their version of the article (e.g. in Word or Tex form) to their personal website or institutional repository. Authors requiring further information regarding Elsevier's archiving and manuscript policies are encouraged to visit:
Environmental and Experimental Botany 01/2011; 71(3):345--351. · 2.98 Impact Factor
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ABSTRACT: Recently developed video editing techniques have enabled us to create realistic synthesized videos. Therefore, using video data as evidence in places such as courts of law requires a method to detect forged videos. In this study, we developed an approach to detect suspicious regions in a video of a static scene on the basis of the noise characteristics. The image signal contains irradiance-dependent noise the variance of which is described by a noise level function (NLF) as a function of irradiance. We introduce a probabilistic model providing the inference of an NLF that controls the characteristics of the noise at each pixel. Forged pixels in the regions clipped from another video camera can be differentiated by using maximum a posteriori estimation for the noise model when the NLFs of the regions are inconsistent with the rest of the video. We demonstrate the effectiveness of our proposed method by adapting it to videos recorded indoors and outdoors. The proposed method enables us to highly accurately evaluate the per-pixel authenticity of the given video, which achieves denser estimation than prior work based on block-level validation. In addition, the proposed method can be applied to various kinds of videos such as those contaminated by large noise and recorded with any scan formats, which limits the applicability of the existing methods.
IEEE Transactions on Information Forensics and Security 01/2011; · 1.34 Impact Factor
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ABSTRACT: We consider the asymptotic performance of a class of linear receivers in multiple-input multiple-output (MIMO) multiple access channels (MAC). Under the assumption that the number of transmitters K and the number of receive antennas N grow large at the same rate and that the receiver has only an imperfect estimate of the channel matrix, we derive deterministic equivalents for the signal-to-interference-plus-noise-ratio (SINR) at the receiver output. Since we assume that the channel matrix has a variance profile, i.e., different matrix entries exhibit different variances, the results are useful for the analysis of network MIMO systems where a user terminal (UT) sees a different path loss to different cooperative base stations (BSs). Our simulation results show that the asymptotic performance predictions are accurate for even small values of N and K.
Signals, Systems and Computers (ASILOMAR), 2010 Conference Record of the Forty Fourth Asilomar Conference on; 12/2010
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ABSTRACT: In various cancer cells, over-expression or mutation of epidermal growth factor (EGF) receptors is experimentally observed, and induces abnormal activation of intracellular signaling proteins, followed by continuous cell proliferation via dysfunctional gene regulatory networks. Since the activation process of EGF receptors on cell membrane is complicated and not fully understood, it is still a challenging work to develop the mathematical model from the viewpoint of cancer therapy such as drug discovery. In this paper, we develop a particle simulator on EGF-induced activation of EGF receptors on cell membrane. The engine of our simulator is based on the Hybrid Null-event Monte Carlo algorithm. The advantage is that our simulator is capable of evaluating ”lateral signaling” of EGF receptors, and directly comparing to the corresponding experimental data that shows a distribution of activated EGF receptors.
Control Automation and Systems (ICCAS), 2010 International Conference on; 11/2010
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T. Ito,
M. Osakabe,
K. Ida,
M. Yoshinuma, M. Kobayashi,
M. Goto,
S. Murakami,
M. Isobe,
S. Kobayashi,
K. Toi,
K. Ogawa,
Y. Takeiri,
S. Okamura
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ABSTRACT: A tangential Fast Ion Charge eXchange Spectroscopy is newly applied on a Large Helical Device (LHD) for co/countercirculating fast ions, which are produced by high energy tangential negative-ion based neutral beam injection. With this new observation geometry, both the tangential-neutral beam (NB) and a low-energy radial-NB based on positive ions can be utilized as probe beams of the measurement. We have successfully observed Doppler-shifted H-alpha lights due to the charge exchange process between the probing NB and circulating hydrogen ions of around 100 keV in LHD plasmas.
Review of Scientific Instruments 11/2010; · 1.37 Impact Factor
