Hiroshi YAMAUCHI Shigekazu KUNIYOSHI Masatoshi SAKAI Kazuhiro KUDO
Step-edge vertical channel organic field-effect transistors (SVC-OFETs) with a very short channel have been fabricated by a novel selective electrospray deposition (SESD) method. We propose the SESD method for the fabrication of SVC-OFETs based on a 6,13-bis(triisopropyl-silylethynyl) pentacene (TIPS-pentacene) semiconductor layer formed by SESD. In the SESD method, an electric field is applied between the nozzle and selective patterned electrodes on a substrate. We demonstrated that the solution accumulates on the selected electrode pattern by controlling the voltage applied to the electrode.
Asami OHTAKE Seiko UCHINO Kunio AKEDO Masanao ERA Koichi SAKAGUCHI
The numerical dispersibility measurement system was fabricated based on optical transparency to objectively evaluate undetectable dispersibility by naked eyes. The small deference of dispersibility and the dispersibility behaviors were simultaneously elucidated by the system. The abundance of octadecyl groups was also discussed from the result of dispersibility behaviors. The objective numerical evaluation is needed for precise analysis of dispersibility with respect to graphene, graphene derivatives and graphene related materials.
A transmission ellipsometric method without an aperture was recently developed to characterize the electro-optic (EO) performance of EO polymers. The method permits much simpler optical setup compared to the reflection method, and allows easy performance of the incident angle dependence measurements using a conventional glass substrate and uncollimated beam. This paper shows the usefulness of this method for a simple and reliable evaluation of the EO coefficient both for organic and inorganic EO materials, as well as analysis for uniaxial anisotropic materials.
In recent years, there has been a significant growth in the importance of data mining of graph-structured data due to this technology's rapid increase in both scale and application areas. Many previous studies have investigated decision tree learning on Semantic Web-based linked data to uncover implicit knowledge. In the present paper, we suggest a new random forest algorithm for linked data to overcome the underlying limitations of the decision tree algorithm, such as local optimal decisions and generalization error. Moreover, we designed a parallel processing environment for random forest learning to manage large-size linked data and increase the efficiency of multiple tree generation. For this purpose, we modified the previous candidate feature searching method of the decision tree algorithm for linked data to reduce the feature searching space of random forest learning and developed feature selection methods that are adjusted to linked data. Using a distributed index-based search engine, we designed a parallel random forest learning system for linked data to generate random forests in parallel. Our proposed system enables users to simultaneously generate multiple decision trees from distributed stored linked data. To evaluate the performance of the proposed algorithm, we performed experiments to compare the classification accuracy when using the single decision tree algorithm. The experimental results revealed that our random forest algorithm is more accurate than the single decision tree algorithm.
Ryosuke KIKUCHI Satoshi USUI Kuniaki TANAKA Hiroaki USUI
Polyimide thin films were prepared by vapor-deposition polymerization. Naphthalene carboxylic dianhydride (NTCDA) was coevaporated with either diamino naphthalene (DAN) or diamino benzophenone (DAB). Coevaporation of dianhydride and diamines yielded thin films of polyamic acids. A polyimide thin film was obtained by annealing the codeposited film of NTCDA-DAB. On the other hand, the codeposited film of NTCDA-DAN was not imidized by annealing. In both cases, chemical structures of the products were not largely influenced by the molar ratio of depositing monomers if sufficient amount of diamine molecules are supplied in the coevaporation process.
Takeshi FUKUDA Tomokazu KURABAYASHI Hikari UDAKA Nayuta FUNAKI Miho SUZUKI Donghyun YOON Asahi NAKAHARA Tetsushi SEKIGUCHI Shuichi SHOJI
We report a real time method to monitor the chemical reaction in microdroplets, which contain an organic dye, 5(6)-carboxynaphthofluorescein and a CdSe/ZnS quantum dot using fluorescence spectra. Especially, the relationship between the droplet size and the reaction rate of the two reagents was investigated by changing an injection speed.
Nobuo SATOH Shigetaka KATORI Kei KOBAYASHI Kazumi MATSUSHIGE Hirofumi YAMADA
We have investigated both the film thickness and surface potential of organic semiconductors deposited on two kinds of electrodes by the simultaneous observation with the dynamic force microscopy (DFM)/Kelvin-probe force microscope (KFM). To clarify the interfacial properties of organic semiconductor, we fabricated samples that imitated the organic light emitting diode (OLED) structure by depositing bis [$N,N '$-(1-naphthyl)-$N,N '$-phenyl] benzidine ($alpha$-NPD) and tris (8-hydroxyquinolinato) aluminum (Alq$_{3}$), respectively, on indium-tin-oxide (ITO) as anode and aluminum (Al) as cathode by the vacuum evaporation deposition using intersecting metal shadow masks. This deposition technique enables us to fabricate four different areas in the same substrate. The crossover area of the deposited thin films were measured by the DFM/KFM, the energy band diagrams were depicted and we considered that the charge behavior of the organic semiconductor depended on the material and the structure.
Nagayoshi YAMASHITA Masayuki NUMAO Ryutaro ICHISE
Since it is difficult to understand or predict research trends, we proposed methodologies for understanding and predicting research trends in the sciences, focusing on the structures of grants in the Japan Society for the Promotion of Science (JSPS), a Japanese funding agency. Grant applications are suitable for predicting research trends because these are research plans for the future, different from papers, which report research outcomes in the past. We investigated research trends in science focusing on research histories identified in grant application data of JSPS. Then we proposed a model for predicting research trends, assuming that breakthrough research encourages researchers to change from their current research field to an entirely new research field. Using breakthrough research, we aim to obtain higher precision in the prediction results. In our experimental results, we found that research fields in Informatics correlate well with actual scientific research trends. We also demonstrated that our prediction models are effective in actively interacting research areas, which include Informatics and Social Sciences.
Xiaoming HU Yinchun YANG Jian WANG Huajie XU Wenan TAN
Presently, many identity-based proxy signature (IBPS) schemes have been proposed, but most of them require high computational costs and the proposed security model for IBPS is not enough complete. To overcome this weakness, Gu et al. recently proposed a framework and a detailed security model for IBPS. They also proposed an efficient IBPS scheme and proved the unforgeability of their scheme in the standard model. However, in this letter, we demonstrate that Gu et al.'s scheme fails to satisfy the property of unforgeability because it can not resist the following attacks: after getting a private key, an adversary behaving as a malicious signer can forge a private key on any identity without the help of the private key generator (PKG); after getting a delegation, an adversary behaving as a malicious proxy signer can forge a proxy signing key on any delegation without the agreement of the original signer; after getting a signature, an adversary behaving as a malicious user can forge a signature on any identity without the private key or forge a proxy signature on any warrant without the proxy signing key.
Chen CHEN Kai LU Xiaoping WANG Xu ZHOU Zhendong WU
Most existing deterministic multithreading systems are costly on pipeline parallel programs due to load imbalance. In this letter, we propose a Load-Balanced Deterministic Runtime (LBDR) for pipeline parallelism. LBDR deterministically takes some tokens from non-synchronization-intensive threads to synchronization-intensive threads. Experimental results show that LBDR outperforms the state-of-the-art design by an average of 22.5%.
Hao ZHANG Mengtian RONG Tao LIU
In this letter, we propose a new intra-field deinterlacing algorithm based on an edge dependent weighted filter (EDWF). The proposed algorithm consists of three steps: 1) calculating the gradients of three directions (45°, 90°, and 135°) in the local working window; 2) achieving the weights of the neighboring pixels by exploiting the edge information in the pixel gradients; 3) interpolating the missing pixel using the proposed EDWF interpolator. Compared with existing deinterlacing methods on different images and video sequences, the proposed algorithm improves the peak signal-to-noise-ratio (PSNR) while achieving better subjective quality.
Shuta KAKO Osamu TAKYU Takeo FUJII
In this paper, we propose a secondary user (SU) resource assignment algorithm for a multi-hop (MH) cognitive radio network to improve the end-to-end throughput. In the MH networks used for spectrum sharing, each SU needs to improve the throughput by taking the primary user (PU) protection into account. For overcoming this problem, we estimate the PU acceptable received power, which is determined by the acknowledgment packet (ACK) power from the PU receiver at each SU. With this estimation, we propose an SU optimal transmit power control algorithm to not only maximize the end-to-end throughput of the SU MH flow but also maintain the considered PU acceptable interference power. In this study, a distributed joint allocation algorithm has been used to solve the optimization problem and to effectively allocate the power of each SU.
In Recent years, a paradigm of optimization algorithms referred to as “meta-heuristics” have been gaining attention as a means of obtaining approximate solutions to optimization problems quickly without any special prior knowledge of the problems. Meta-heuristics are characterized by flexibility in implementation. In practical applications, we can make use of not only existing algorithms but also revised algorithms that reflect the prior knowledge of the problems. Most meta-heuristic algorithms lack mathematical grounds, however, and therefore generally require a process of trial and error for the algorithm design and its parameter adjustment. For one of the resolution of the problem, we propose an approach to design algorithms with mathematical grounds. The approach consists of first constructing a “framework” of which dynamic characteristics can be derived theoretically and then designing concrete algorithms within the framework. In this paper, we propose such a framework that employs two following basic strategies commonly used in existing meta-heuristic algorithms, namely, (1) multipoint searching, and (2) stochastic searching with pseudo-random numbers. In the framework, the update-formula of search point positions is given by a linear combination of normally distributed random numbers and a fixed input term. We also present a stability theory of the search point distribution for the proposed framework, using the variance of the search point positions as the index of stability. This theory can be applied to any algorithm that is designed within the proposed framework, and the results can be used to obtain a control rule for the search point distribution of each algorithm. We also verify the stability theory and the optimization capability of an algorithm based on the proposed framework by numerical simulation.
To immobilize cytochrome $c$ (cyt.,$c$) on ITO electrode with keeping its direct electron transfer (DET) activity, 10-carboxydecylphosphonic acid (10-CDPA) self-assembled monolayer (SAM) film was formed on ITO electrode. After 100 times washing process with exchanging phosphate buffer saline solution in the cell to fresh one, extit{in situ} slab optical waveguide (SOWG) absorption spectral measurement proved that about 80% of cyt.,$c$ immobilized on 10-CDPA modified ITO electrode was adsorbed on ITO electrode. Additionally SOWG spectral change of cyt.,$c$ between oxidized and reduced forms was observed with setting the ITO electrode potential at 0.3 and $-$0.3,V vs. Ag/AgCl, respectively showing DET reaction between cyt.,$c$ and ITO electrode occurred. About 30% of a monolayer coverage was estimated from the coulomb amount in the surface area of oxidation and reduction peaks on cyclic voltammetry (CV) data. CV peak current maintained 84% for ITO electrode modified with 10-CDPA SAM film after 60,min continuous scan with 0.1,V/sec from 0.3 and $-$0.3,V vs. Ag/AgCl.
This paper proposes a novel scheme for sequential orthogonal frequency division multiplexing channel estimation on the receiver side.The scheme comprises two methods: one improves estimation accuracy and the other reduces computational complexity. Based on a state-space model, the first method appropriately considers frequency correlation in an approach that derives a narrow-band channel gain for multiple pilot subcarriers; such consideration of frequency correlation leads to an averaging effect in the frequency domain. The second method is based on the first one and forces the observation matrix into a sparse bidiagonal matrix in order to decrease the number of mathematical processes. The proposed scheme is verified by numerical analysis.
Least squares error (LSE) method adopted recursively can be used to track the frequency and amplitude of signals in steady states and kinds of non-steady ones in power system. Taylor expansion is used to give another version of this recursive LSE method. Aided by variable-windowed short-time discrete Fourier transform, recursive LSEs with and without Taylor expansion converge faster than the original ones in the circumstance of off-nominal input singles. Different versions of recursive LSE were analyzed under various states, such as signals of off-nominal frequency with harmonics, signals with step changes, signals modulated by a sine signal, signals with decaying DC offset and additive Gaussian white noise. Sampling rate and data window size are two main factors influencing the performance of method recursive LSE in transient states. Recursive LSE is sensitive to step changes of signals, but it is in-sensitive to signals' modulation and singles with decaying DC offset and noise.
Yan Shen DU Ping WEI Hua Guo ZHANG Hong Shu LIAO
In this work, the differential received signal strength based localization problem is addressed. Based on the measurement model, we present the constrained weighted least squares (CWLS) approach, which is difficult to be solved directly due to its nonconvex nature. However, by performing the semidefinite relaxation (SDR) technique, the CWLS problem can be relaxed into a semidefinite programming problem (SDP), which can be efficiently solved using modern convex optimization algorithms. Moreover, the SDR is proved to be tight, and hence ensures the corresponding SDP find the optimal solution of the original CWLS problem. Numerical simulations are included to corroborate the theoretical results and promising performance.
Takashi YAMAMOTO Shigemasa TAKAI
In this paper, we consider a decentralized failure diagnosis problem for discrete event systems. For a conjunctively codiagnosable system, there exists a conjunctive decentralized diagnoser that can detect the occurrence of any failure within a uniformly bounded number of steps. We present a method for synthesizing such a conjunctive decentralized diagnoser as an online diagnoser.
Taishi NOMA Dai TAGUCHI Takaaki MANAKA Mitsumasa IWAMOTO
Displacement current measurement (DCM) is widely used as a method for analyzing carrier behaviors of organic devices. Carrier behaviors are analyzed using transient currents. On the other hand, electric-field-induced optical second-harmonic generation (EFISHG) measurement is capable of directly probing carrier motions in organic devices, where the migration of electric field stemmed from carriers is measured. In this study, we employed the DCM and EFISHG measurements for analyzing interfacial carrier behaviors in Au/pentacene/polyimide (PI)/indium-tin-oxide (ITO) double layer organic devices, where interfacial accumulated charges and electric fields formed in the pentacene layer were explored.
The mammalian cochlear consists of highly nonlinear components: lymph (viscous fluid), a basilar membrane (vibrating membrane in the viscous fluid), outer hair cells (active dumpers for the basilar membrane), inner hair cells (neural transducers), and spiral ganglion cells (parallel spikes density modulators). In this paper, a novel spiral ganglion cell model, the dynamics of which is described by an asynchronous cellular automaton, is presented. It is shown that the model can reproduce typical nonlinear responses of the spiral ganglion cell in the mammalian cochlea, e.g., spontaneous spiking, parallel spike density modulation, and adaptation. Also, FPGA experiments validate reproductions of these nonlinear responses.