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ABSTRACT: The connected dominating set (CDS) has been extensively used for routing and broadcast in wireless ad hoc networks. While existing CDS protocols are successful in constructing CDS of small size, they either require localized information beyond immediate neighbors, lack the mechanism to properly handle nodal mobility, or involve lengthy recovery procedure when CDS becomes corrupted. In this paper, we introduce the timer-based CDS protocols, which first elect a number of initiators distributively and then utilize timers to construct a CDS from initiators with the minimum localized information. We demonstrate that our CDS protocols are capable of maintaining CDS in the presence of changes of network topology. Depending on the number of initiators, there are two versions of our timer-based CDS protocols. The Single-Initiator (SI) generates the smallest CDS among protocols with mobility handling capability. Built on top of SI, the Multi-Initiator (MI) version removes the single point of failure at single-initiator and possesses most advantages of SI. We evaluate our protocols by both the ns-2 simulation and an analytical model. Compared with the other known CDS protocols, the simulation results demonstrate that both SI and MI produce and maintain CDS of very competitive size. The analytical model shows the expected convergence time and the number of messages required by SI and MI in the construction of CDS, which match closely to our simulation results. This helps to establish the validity of our simulation.
IEEE Transactions on Mobile Computing 11/2011; · 2.28 Impact Factor
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ABSTRACT: An algorithm is proposed for improving the robustness of an ear biometric system with the aim of developing a surveillance-system based on ear biometrics. To deal with pose variations that are rotated in depth, the Gabor jets of different poses are estimated and used as training data for a discriminant analysis-based classifier. Experimental evaluations show the effectiveness of the proposed algorithm, and the potential for improving the robustness of a single-view-based ear surveillance-system.
Biometrics and Kansei Engineering (ICBAKE), 2011 International Conference on; 10/2011
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ABSTRACT: The design and implementation of an on-demand DC grid in home is proposed. This paper is one of the research of informatization of energy that purposing to realize a highly efficient power distribution systems which does not impair quality of human life. Based on the idea of the informatization of energy, we propose the energy routing switches and peripherals that realize coloring of energy by circuit switching in this paper, and by using this, an on-demand energy network is designed and implemented based on PoE as the physical and data-link layer protocol. The prototype has compatibility with PoE type A, which uses two pairs of a UTP cable, and uses the rest two pairs for our own extension. In an on-demand energy network which we propose, power is not supplied until a powered device sends an explicit request presenting the required quantity and quality of electric power and the request is accepted by the energy network. By this we can suppress the power consumption within the specified target even when the demands from devices are too much. The network itself chooses best matching of a source and a device, and makes reservation of a path. This system allows the network to be on-demand multi sources energy routing and snatching other devices' energy by considering precedence on the proposed architecture with implemented routing switches. In addition to that DC transmission in home can help more highly efficient use of energy. Numbers of home electronics appliances consume DC energy at the final stage. Solar panels, self-generated electricity and most of other dispersed power sources also generate DC. However, power provide from an electric power company are AC, which makes it necessary for electronic devices to convert from AC to DC. Use of AC to DC converter is not only low efficient but also use much of materials when manufacturing. By transmitting the electricity in DC, it can lessen these losses which occur from the conversion.
Applications and the Internet (SAINT), 2011 IEEE/IPSJ 11th International Symposium on; 08/2011
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T Shimizu,
K Yamanoi, K Sakai,
M Cadatal-Raduban,
T Nakazato,
N Sarukura,
M Kano,
A Wakamiya,
D Ehrentraut,
T Fukuda,
M Nagasono,
T Togashi,
S Matsubara,
K Tono,
A Higashiya,
M Yabashi,
H Kimura,
H Ohashi,
T Ishikawa
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ABSTRACT: We report an over one-order-of magnitude improvement in the response time of conventional hydrothermal method-grown zinc oxide (ZnO) scintillator by introducing additional quenching channels via intentional indium ion doping. A 3-ps fluorescence decay time constant is achieved, therefore making it the fastest scintillator operating below 100 nm to date. Using this indium-doped ZnO, relative jitter between extreme ultraviolet free electron laser (EUV-FEL) probe and optical pump pulses is evaluated to be less than 3 ps. Moreover, pulses from these sources can be synchronized with 3-ps accuracy through in-situ observation of relative time difference in single-shot base. (C) 2011 The Japan Society of Applied Physics
Applied Physics Express 01/2011; 4(6). · 3.01 Impact Factor
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ABSTRACT: We demonstrate a high-current back-illuminated InGaAs/InP p-i-n photodiode (PD), whose depleted region comprises partially depleted-absorbing, depleted-absorbing, and depleted-nonabsorbing layers to increase RF power output. The back-illuminated PD has an advantage of small thermal resistance between a photoabsorber and a heat sink for avoiding catastrophic thermal failure. The thermal resistance decreases with an increase in the detecting area; however, it simultaneously increases the capacitance, imposing a limitation on the RF response. To reduce the capacitance, we have incorporated a depleted-nonabsorbing layer into a partially depleted absorber PD structure that photogenerated electrons can drift trough. We have fabricated two samples, one with a detecting area of 50 μm, and the other with a detecting area of 70 μm in diameter. Both PDs show high RF power outputs of 28.7 and 29.0 dBm at a frequency of 5 GHz, and 25.7 and 26.7 dBm at each -3-dB frequency of 10.5 and 7 GHz, respectively.
IEEE Transactions on Microwave Theory and Techniques 12/2010; · 1.85 Impact Factor
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ABSTRACT: We have proposed the new micro column electron beam microscope fabricated with multi-gated field emitter array based on the first result that a crossover successfully observed with quintuple-gated FEA. In order to realize the fine focused electron beam less than several ten nm in diameter, the initial emission angle after emitting from tip surface has to be controlled narrowly. In this report, it was described that we have introduced a suppressor gate which was located below tip and fabricated double-gated field emitter array with extractor. It was demonstrated that the suppressor gate had an emission angle narrowed successfully.
Vacuum Nanoelectronics Conference (IVNC), 2010 23rd International; 08/2010
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T. Shimizu,
K. Yamamoi,
E. Estacio,
T. Nakazato, K. Sakai,
N. Sarukura,
D. Ehrentraut,
T. Fukuda,
M. Nagasono,
T. Togashi,
A. Higashiya,
M. Yabashi,
T. Ishikawa,
H. Ohashi,
H. Kimura
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ABSTRACT: A hydrothermal method-grown, Fe-doped ZnO crystal, was excited by the XFEL prototype at Spring-8 facility. The scintillation signal exhibited <;10-ps rise time and <;100-ps decay time; making it the fastest scintillator for XFEL timing studies.
Lasers and Electro-Optics (CLEO) and Quantum Electronics and Laser Science Conference (QELS), 2010 Conference on; 06/2010
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ABSTRACT: We present a coupled-wave analysis for square-lattice photonic crystal lasers with transverse electric polarization. A model consisting of eight plane waves coupled by Bragg diffraction is used to describe two-dimensional optical coupling. The resonant frequencies and threshold criteria for the modes of oscillation have been determined for the case of index periodicity with a lattice of circular holes. The spatial intensity distributions of these resonant modes have also been calculated. For the fundamental modes, we have investigated how the intensity distribution varies as a function of coupling strength. The dependence of the threshold gain of these modes on hole size has also been elucidated. This semianalytical approach provides a comprehensive understanding of square-lattice photonic crystal lasers and allows more effective optimization of their cavity design.
IEEE Journal of Quantum Electronics 06/2010; · 1.88 Impact Factor
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ABSTRACT: Distributed Denial of Service (DDoS) attacks are one of the most damaging threats against Internet based applications. Many of the DDoS defense mechanisms may unintentionally deny a certain portion of legitimate user accesses by mistaking them as attackers or may simply not block enough traffic to adequately protect the victim. Other better performing systems have not yet to reach adoption because of designs that require a substantial investment into the Internet infrastructure before offering much effectiveness. This paper proposes Heimdall, a novel traffic verification based framework to protect legitimate traffic from bilateral damages. Based on a proof-of-work technique and application of distributed hash ID, aside from protecting established connections, our system can validate new initial request for communication and open valid channels between users and the protected server. Through intensive simulation experiments on the ns-2 network simulator, we verified that Heimdall scheme can effectively protect legitimate communications and filter out malicious flows with very high accuracy.
Consumer Communications and Networking Conference (CCNC), 2010 7th IEEE; 02/2010
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ABSTRACT: We develop a one hand drive wheelchair with original manipulation mechanism and power assist mechanism. In this investigation, first, we improve the transfer mechanism of this wheelchair. As a result, using an improved mechanism, the running resistance of the wheelchair decreased with about 1/2 to the previous one. The effects of this improvement are verified by long distance drive experiment using some one hand drive type wheelchairs. Secondly, we develop the assist unit, which has a new on/off mechanism constructed by link and sliding mechanism, in order to realize the sure assist torque transformation. During assist, improved unit surely keeps the distance of two rollers, which transfer assist torque to tires. Therefore, assist torques, provided by DC motor, are surely transfer to tires.
Robotics and Biomimetics (ROBIO), 2009 IEEE International Conference on; 01/2010
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ABSTRACT: Electrical appliances and electric vehicles (EV) require reduction of electrical consumption. Then, we have developed a novel permanent magnet motor for energy saving. In this paper, we propose the novel motor that can change magnetic flux by a new method magnetizing a permanent magnet and clarify the principle and unique characteristics. Furthermore, the results of analysis and experiments prove that the novel motor can change the flux of permanent magnet on load and has realization for a variable speed drive with high performance.
Electrical Machines and Systems, 2009. ICEMS 2009. International Conference on; 12/2009
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ABSTRACT: Humans are subjected to large amounts of stress during daily life. Mental health and stress management in daily life are essential to prevent mental illness. We investigate whether or not mental stress shows recognizable displacements of measurable physiological signals. We have therefore been developing new physiological signal sensors for measurement of daily stress. The present study focused on ¿body-sound¿, as the sounds generated inside the human body and included large amounts of information about physiological and mental conditions. We then developed a prototype of body-sound sensor, and measured heart rate and respiratory rate simultaneously from body-sound at the neck using continuous wavelet transformation. Finally, we compared the body-sound with electrocardiogram and respiratory waveform to evaluate the performance of proposed method.
Information Technology and Applications in Biomedicine, 2009. ITAB 2009. 9th International Conference on; 12/2009
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ABSTRACT: We propose an optically controlled multiple-beam phased array antenna employing spatial and wavelength multiplexing. We have developed the prototype of the optical beam-former, which enables control of 10 beams individually, and demonstrated at 18 GHz.
Microwave Photonics, 2009. MWP '09. International Topical Meeting on; 11/2009
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ABSTRACT: We proposed a high-current backside-illuminated InGaAs/InP p-i-n photodiode (PD) with a non-absorbing drift region, and demonstrated an RF power output of 29.0 dBm at 5 GHz, a 3-dB bandwidth of 7 GHz, and a third order intercept point of 31 dBm at 2 GHz using a 70-mum-diameter PD.
Microwave Photonics, 2009. MWP '09. International Topical Meeting on; 11/2009
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K. Kosuge,
Y. Hirata,
Jina Lee,
A. Kawamura,
K. Hashimoto,
S. Kagami,
Yu. Hayashi,
N. Yokoshima,
H. Miyazawa,
R. Teranaka,
Y. Natsuizaka, K. Sakai,
M. Koizumi,
J. Koyama,
N. Kanayama,
S. Tezuka,
H. Torimitsu
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ABSTRACT: In this paper, we introduce an automatic dishwashing robot system, which consists of two 7-DOF manipulators, novel grasping system with hook structure, sensing system and the controller. We introduce each component of the system and experiments are performed to illustrate the effectiveness of the developed robot system.
Mechatronics and Automation, 2009. ICMA 2009. International Conference on; 09/2009
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ABSTRACT: We designed a tapered unstable-resonator laser diode consisting of a 3-mm-long tapered amplifier and a fiber-Bragg-grating reflector, both of which were coupled with a biconical microlens at the fiber end. The amplifier was composed of an InGaAs single quantum well inside a waveguide, which had an optical confinement factor of 1.2%, a tapered current constriction of 6<sup>deg</sup> in full angle, and an input width of 10 mum. The grating reflector was fabricated in a polarization-maintaining fiber with a reflectivity of 99% and a reflection bandwidth of 0.19 nm. A biconical microlens with vertical and horizontal radii of 3.5 and 11 mum, respectively, was fabricated at the fiber end to increase the coupling efficiency between the tapered amplifier and the grating reflector. An output power of 3.2 W was obtained at a wavelength of 1064 nm in multimode operation for the grating reflection bandwidth.
IEEE Photonics Technology Letters 09/2009; · 2.19 Impact Factor
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ABSTRACT: The connected dominating set (CDS) has been commonly used for routing and broadcast in mobile ad hoc networks (MANETs). Considering the applications of MANETs, it is generally preferred that the CDS protocol not only creates CDS of small size, incurs less communication and computational overheads, adapts to the nodal mobility, but also generates CDS as quickly as possible. Unfortunately, none of the existing CDS protocols possesses all of these desirable properties. In this paper, we propose an algorithm to rapidly grow a CDS tree from an initiator. By incorporating this algorithm with the Multi-Initiator CDS protocol, we have created the CDS protocol for MANETs which enjoys all the aforementioned desirable properties. The simulation results validate that our proposed protocol achieves its design goals. In addition, an analytical model is provided that can accurately estimate the convergence time required by our proposed CDS protocol.
Communications, 2009. ICC '09. IEEE International Conference on; 07/2009
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Y. Makida,
A. Yamamoto,
K. Yoshimura,
K.-i. Tanaka,
J. Suzuki,
S. Matsuda,
M. Hasegawa,
A. Horikoshi,
R. Shinoda, K. Sakai,
S. Mizumaki,
R. Orito,
Y. Matsukawa,
A. Kusumoto,
J.W. Mitchell,
R.E. Streitmatter,
T. Hams,
M. Sasaki,
N. Thakur
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ABSTRACT: An ultra-thin superconducting solenoid has been developed for a cosmic-ray spectrometer ballooning over Antarctica, which is named BESS-Polar II. The coil with a diameter of 0.9 m, a length of 1.4 m and a thickness of 3.5 mm, is wound with high-strength aluminum stabilized superconductor and provides 0.8 T in the spectrometer. Based on the experience at the BESS-Polar-I solenoid flight for nine days in 2004, the BESS-Polar-II solenoid, which was cryogenically improved, realized a persistent current mode operation for 25 days in the second flight campaign in December 2007 though January 2008. It has contributed to accumulate the cosmic-ray observation data with 4700 million events and 16 terabyte in a hard disk unit. This report will describe the second solenoid performance during the flight.
IEEE Transactions on Appiled Superconductivity 07/2009; · 1.04 Impact Factor
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Hao Wang,
H.P.E. Xu,
Wai Tung Ng,
K. Fukumoto,
K. Abe,
A. Ishikawa,
Y. Furukawa,
H. Imai,
T. Naito,
N. Sato, K. Sakai,
S. Tamura,
K. Takasuka
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ABSTRACT: A transistor with an orthogonal gate (OG) electrode is proposed to improve dv / dt capability, reduce the gate-to-drain overlap capacitance ( C <sub>gd</sub>), and improve figure of merit (FOM). The OG has both a horizontal section and a vertical section for MOS gate control. This 30-V device is implemented in a 0.18-mum CMOS-compatible process. Comparing to a conventional extended drain MOSFET transistor with the same voltage rating and device size, four times higher dv / dt capability and 53% improvement in FOM are observed.
IEEE Electron Device Letters 01/2009; · 2.85 Impact Factor
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ABSTRACT: The effect of surgical procedure on breathing movement and the effect of characteristics of breathing movement on changes
in heart rate and blood pressure during actual endoscopic nasal surgery were analyzed using analysis of variance and Bayesian
network modeling. As the result, the probabilistic causal relationship between respiratory irregularities, increasing blood
pressure and patients’ complaint of pain was found. This result is expected to be used as patient pain and stress detection
method without discomfort during actual surgery under local anesthesia.
12/2008: pages 2048-2051;
