We address the global asymptotic stability of FAST TCP, especially considering cross traffics, time-varying network feedback delay, and queuing delay dynamics at link. Exploiting the inherent dynamic property of FAST TCP, we construct two sequences that represent the lower and upper bound variations of the congestion window in time. By showing that the sequences converge to the equilibrium point of the congestion window, we establish that FAST TCP in itself is globally asymptotically stable without any specific conditions on the tuning parameter α or the update gain γ.

This paper presents a novel decision feedback equalizer (DFE) with block delay detection for the joint transceiver design that uses channel state information (CSI). The block delay detection in the proposed DFE offers a degree of freedom for optimizing the precoder of the transmitter, provided the transmission power is constrained. In the proposed DFE, the feedforward matrix is devised to enable a block-based equalizer that can be cooperated with an intrablock decision feedback equalizer for suppressing the intersymbol interference (ISI) for the transmitted block with a certain block delay. In this design, the interblock interference (IBI) for the delay block is eliminated in advance by applying the recently developed oblique projection framework to the implementation of the feedforward matrix. With knowledge of full CSI, the block delay and the associated block-based precoder are jointly designed such that the average bit-error-rate (BER) is minimized, subject to the transmission power constraint. Separate algorithms are derived for directly determining the BER-minimized block delays for intrablock minimum mean-squared error (MMSE) and zero-forcing (ZF) equalization criteria. Theoretical derivations indicate that the proposed MMSE design simultaneously maximize the Gaussian mutual information of a transceiver, even under the cases of existing IBI. Simulation results validate the proposed DFE for devising an optimum transceiver with CSI, and show the superior BER performance of the optimized transceiver using proposed DFE. Relying on analytic results and simulation cases also builds a sub-optimum MMSE design of the proposed DFE using the BER-minimized block delay for ZF criterion, which exhibits almost identical BER performance as the proposed MMSE design in most of the signal-to-noise ratio (SNR) range.

This paper presents an approach based on character recognition to searching for keywords in on-line handwritten Japanese text. It employs an on-line character classifier and an off-line classifier or a combined classifier, which produce recognition candidates, and it searches for keywords in the lattice of candidates. It integrates scores to individually recognize characters and their geometric context. We use quadratic discriminant function(QDF) or support vector machines(SVM) models to evaluate the geometric features of individual characters and the relationships between characters. This paper also presents an approach based on feature matching that employs on-line or off-line features. We evaluate three recognition-based methods, two feature-matching-based methods, as well as ideal cases of the latter and concluded that the approach based on character recognition outperformed that based on feature matching.

In this paper, we investigate the impact of different sub-band spreading bandwidth (SSBW) on a direct sequence (DS) multiband (MB) ultra wideband (UWB) system in multipath and narrowband interference over realistic UWB channel models based on actual measurements. As an approach to effectively mitigate multipath and narrowband interference, the DS-MB-UWB system employs multiple sub-bands instead of a wide single band for data transmission. By using spreading chips with different duration settings, the SSBW can be manipulated. As a result, it is observed that increasing SSBW does not always improve system performance. Optimum SSBW values exist and are found to vary in accordance to different operating parameters such as the number of sub-bands and types of propagation channel model. Additionally, we have also found that system performance in the presence of narrowband interference is heavily dependent on the number of employed sub-bands.

Magnetospinography (MSG) is one of the most promising techniques to detect the nerve activity of spinal cords thanks to its noninvasiveness and high spatial/temporal resolutions. Multichannel superconducting quantum interference device (SQUID) MSG measurement systems optimized for supine subjects have been developed previously and employed in clinical applications in hospitals. Magnetic source analyses of MSG data based on spatial filter techniques reveal the transition of reconstructed current distributions adjacent to the spinal cord. The propagation of the neural signals was noninvasively visualized. The MSG measurements provide significant diagnostic information such as irregularities in the transitions of the reconstructed current distribution and/or considerable decreases in the current intensity at the lesion. Such functional imaging of the spinal cord in addition to conventional neurologic examinations and morphological imaging will be fairly effective in presurgical lesion localizations of the spinal cord.

We investigated oxidation time dependence of graphene oxide employing modified Hummer method by dynamic light scattering. Oxidation reaction proceeded rapidly within about 24 hours, and was saturated. It is suggested that graphene oxides were not able to freely fragment. This implies that the oxidation reactions occur at the limited sites.

In order to obtain the uniform film having well-defined lead halide-based layer perovskite structure, we proposed squeezed out method. It is found that the optimized condition with respect to docosylammonium bromide is revealed by employing hexadecylammonium bromide among tetradecylammonium bromide, hexadecylammonium bromide and octadecylammonium bromide.

In precoded TDD MIMO systems, precoding is done based on the downlink CSI, which can be predicted according to the outdated uplink CSI. This letter proposes a double-scale channel prediction scheme where frame-scale Kalman filters and pilot-symbol-scale AR predictors jointly predict the needed downlink CSI.

This paper presents a basic investigation of the power imbalance problem with regard to maximum ratio combining (MRC) array antennas for digital TV broadcast reception. First, the relationship between the decrease in the diversity gain and reduction in the received power was investigated using two-element and four-element dipole array antennas by means of a Monte Carlo simulation. The relationship between the decrease in the diversity gain and the number of branches imposed to reduce the received power was also investigated. Then, a simple method of predicting the reduction in the diversity gain under imbalanced power conditions is given using the simulation results. The objective is to determine a criterion associated with the gain reduction that allows us to achieve the required system performance. Finally, the proposed method is confirmed by analysis using a model representing a typical portable digital broadcasting TV set held with both hands that simulates the power imbalance condition.

In order to improve user's privacy in multi-authority Attribute-Based Encryption (ABE), we propose a solution which hides user's attributes by privacy homomorphism, such that not only the “external” adversary fails to access the private attribute of one user by eavesdropping on communications, but also the “internal” Attribute Authorities (AA), who are responsible for issuing attribute keys, are unable to build a full profile with all of the user's attributes by pooling their information on the user's ID. Meanwhile, the use of ID is essential to defend against collusion attack on ABE. Benefiting from privacy homomorphism, by which we distribute the part of the interpolation for the shares abstracted by the hidden attributes into each AA, the performance of the proposed scheme is higher than those of existing ABE schemes.

We propose a novel network traffic matrix decomposition method named Stable Principal Component Pursuit with Frequency-Domain Regularization (SPCP-FDR), which improves the Stable Principal Component Pursuit (SPCP) method by using a frequency-domain noise regularization function. An experiment demonstrates the feasibility of this new decomposition method.

Fluoropolymer thin films were prepared by the ion-assisted vapor deposition polymerization (IAD) of 2-(perfluorohexyl)ethylacrylate (Rf-6). The adhesion strength of the film to substrates was estimated by sonicating the films in water and by immersing the films into dichloro-pentafluoro propane (HCFC225). The Rf-6 polymer films by IAD showed stronger adhesion to glass compared to a spin-coated Teflon AF film. The adhesion strength was improved with increasing ion energy Eion of IAD. The IAD films showed superior adhesion to PET surface compared to the glass substrate. The Rf-6 polymer film was effective as a single-layer antireflective coating. The refractive index of the film was 1.368 (λ = 546 nm), which increased slightly with increasing Eion. IAD can be a promising method to prepare fluoropolymer thin films due to the solvent-less process and the flexibility in controlling the film characteristics by the ion energy.

The Start-frame-delimiter (SFD) is crucial in packet-based communications system since it indicates the end of preamble and the start of a frame. In 802.15 smart utility network system, the function of SFD is extended. Two different SFDs are used for achieving frame synchronization and at the same time, to differentiate coded and uncoded packets. This paper proposes a systematic method for the selection of SFD pair for FSK based systems. The design method is adopted by 802.15.4g Task Group with the backward compatibility to IEEE 802.15.4d systems taken into account. Four selection criteria are specified and discussed to determine the pair of sequences providing least packet error detection rate with the consideration of eliminating the adjacent channel image signal commonly occurred in the low IF receiver. The probability of false alarm and miss detection is analyzed to verify the effectiveness of the proposed selection method. The simulation results confirm that error frame detection rate of 1e-3 can be achieved with selected SFD sequences. The proposed method for selection of SFD pairs ensures a robust packet header and thus better payload protection. The SFD design approach is applicable to other packet-based wireless communication FSK systems with the support of more than one SFD sequence.

The GPS trajectory databases serve as bases for many intelligent applications that need to extract some trajectories for future processing or mining. When doing such tasks, spatio-temporal range queries based methods, which find all sub-trajectories within the given spatial extent and time interval, are commonly used. However, the history trajectory indexes of such methods suffer from two problems. First, temporal and spatial factors are not considered simutaneously, resulting in low performance when processing spatio-temporal queries. Second, the efficiency of indexes is sensitive to query size. The query performance changes dramatically as the query size changed. This paper proposes workload-aware Adaptive OcTree based Trajectory clustering Index (ATTI) aiming at optimizing trajectory storage and index performance. The contributions are three-folds. First, the distribution and time delay of the trajectory storage are introduced into the cost model of spatio-temporal range query; Second, the distribution of spatial division is dynamically adjusted based on GPS update workload; Third, the query workload adaptive mechanism is proposed based on virtual OcTree forest. A wide range of experiments are carried out over Microsoft GeoLife project dataset, and the results show that query delay of ATTI could be about 50% shorter than that of the nested index.

We evaluate the rich-club property of the Internet topology at the autonomous system (AS) level by comparing the Internet AS graphs of traceroute and BGP, and the synthetic graphs of PFP model. The results indicate that, for rich-club coefficient, PFP model can exactly match traceroute AS graphs in the early years around 2002, but it has significantly deviated from the grown AS graphs since about 2010.

BLOCKSUM, also known as KEISANBLOCK in Japanese, is a Latin square filling type puzzle, such as Sudoku. In this paper, we prove that the decision problem whether a given instance of BLOCKSUM has a solution or not is NP-complete.

This survey provides a brief introduction to compressed sensing as well as several major algorithms to solve it and its various applications to communications systems. We firstly review linear simultaneous equations as ill-posed inverse problems, since the idea of compressed sensing could be best understood in the context of the linear equations. Then, we consider the problem of compressed sensing as an underdetermined linear system with a prior information that the true solution is sparse, and explain the sparse signal recovery based on 1 optimization, which plays the central role in compressed sensing, with some intuitive explanations on the optimization problem. Moreover, we introduce some important properties of the sensing matrix in order to establish the guarantee of the exact recovery of sparse signals from the underdetermined system. After summarizing several major algorithms to obtain a sparse solution focusing on the 1 optimization and the greedy approaches, we introduce applications of compressed sensing to communications systems, such as wireless channel estimation, wireless sensor network, network tomography, cognitive radio, array signal processing, multiple access scheme, and networked control.

A self-assembled monolayer having a benzophenone unit as a photoreactive terminal group (BP-SAM) was prepared on an indium-tin oxide (ITO) electrode, on which a hole-transport layer of a phenoxazine-dioctylfluorene copolymer (H5) was spin-coated and irradiated with UV light. After washing the physisorbed H5 molecules, contact angle measurement and ellipsometry showed that the H5 molecules can be tethered to the ITO surface via the BP-SAM. Organic light-emitting diodes (OLEDs) were prepared in the structure of ITO/H5 hole transport layer/tris(8-hydroxyquinolato) aluminum/bathocuproin/LiF/Al electrode with and without the BP-SAM layer on the surface of ITO. The device with the BP-SAM showed higher current density and higher luminance due to the improvement of contact at the ITO/H5 interface by forming covalent bonds via the BP-SAM.

By using electric-field-induced optical second-harmonic generation (EFISHG) measurement, we investigated interfacial carrier behavior in organic solar cells (OSCs) with a blocking layer of bathocuproine (BCP). Results evidently showed that the Maxwell-Wagner type excess charges accumulate on both pentacene/C60 and C60/BCP interfaces. Also, the measurement under short-circuit and open-circuit conditions clearly showed the different photo-induced carrier behaviors in the OSCs devices. Our work proved that the dielectric nature of OSCs dominates the operation of our OSCs and the EFISHG technique is very effective to characterize the dielectric performance of the OSCs.

We outline a number of high temperature superconducting Josephson junction-based devices including superconducting quantum interference devices (SQUIDs) developed for a wide range of applications including geophysical exploration, magnetic anomaly detection, terahertz (THz) imaging and microwave communications. All these devices are based on our patented technology for fabricating YBCO step-edge junction on MgO substrates. A key feature to the successful application of devices based on this technology is good stability, long term reliability, low noise and inherent flexibility of locating junctions anywhere on a substrate.