In this paper, we investigate the transitional dynamics and quasi-periodic solution appearing after the Saddle-Node (SN) bifurcation of a periodic solution in an inductor-coupled asymmetrical van der Pol oscillators with hard-type nonlinearity. In particular, we elucidate, by investigating global bifurcation of unstable manifold (UM) of saddles, that transitional dynamics and quasi-periodic solution after the SN bifurcation appear based on different structure of UM.

In this paper, a multiplication algorithm in extension field Fpm is proposed. Different from the previous works, the proposed algorithm can be applied for an arbitrary pair of characteristic p and extension degree m only except for the case when 4p divides m(p-1) and m is an even number. As written in the title, when p>m, 4p does not divide m(p-1). The proposed algorithm is derived by modifying cyclic vector multiplication algorithm (CVMA). We adopt a special class of Gauss period normal bases. At first in this paper, it is formulated as an algorithm and the calculation cost of the modified algorithm is evaluated. Then, compared to those of the previous works, some experimental results are shown. Finally, it is shown that the proposed algorithm is sufficient practical when extension degree m is small.

In this paper, active frequency selective surfaces (FSS) having a squared aperture with a metal plate loading are described. Active FSS elements using switched PIN diodes are discussed with an equivalent circuit model. A unit cell consists of a square aperture element with metal island loading and one PIN diode placed at the upper gap, considering the vertical polarization. The electromagnetic properties of the active FSS structure are changed by applying dc bias to the substrate, and they can be estimated by the equivalent circuit model of the FSS structure and PIN diode. This active FSS design enables transmission to be switched on or off at 2.3 GHz, providing high transmission when the diodes are in an off state and high isolation when the diodes are on. The equivalent circuit model in the structure is investigated by analyzing transmission and reflection spectra. Measurements on active FSS are compared with numerical calculations. The experimentally observed frequency responses are also scrutinized.

Many applications in wireless sensor networks (WSNs) require the energy efficiency and scalability. Although IEEE 802.15.4/Zigbee which is being considered as general technology for WSNs enables the low duty-cycling with time synchronization of all the nodes in network, it still suffer from its low scalability due to the beacon frame collision. Recently, various algorithms to resolve this problem are proposed. However, their manners to implement are somewhat ambiguous and the degradation of energy/communication efficiency is serious by the additional overhead. This paper describes an Energy-efficient BOP-based Beacon transmission Scheduling (EBBS) algorithm. EBBS is the centralized approach, in which a resource-sufficient node called as Topology Management Center (TMC) allocates the time slots to transmit a beacon frame to the nodes and manages the active/sleep schedules of them. We also propose EBBS with Adaptive BOPL (EBBS-AB), to adjust the duration to transmit beacon frames in every beacon interval, adaptively. Simulation results show that by using the proposed algorithm, the energy efficiency and the throughput of whole network can be significantly improved. EBBS-AB is also more effective for the network performance when the nodes are uniformly deployed on the sensor field rather than the case of random topologies.

A silicon lateral photodiode is fabricated by standard 0.18 µm CMOS process, and the optical detection property is characterized. The photodiode has interdigital electrode structure with the electrode width of 0.22 µm and the electrode spacing of 0.6 µm. At 830 nm wavelength, the responsivity is 0.12 A/W at low bias voltage, and is increased to 0.6 A/W due to avalanche amplification. The bandwidth is also enhanced from 12 MHz at low bias voltage to 100 MHz at the bias voltage close to the breakdown voltage.

This paper represents a novel second harmonic power combining oscillator using mutually synchronized Gunn diodes embedded on slot line resonators. A both-sided MIC technology is adopted in the oscillator. The oscillator consists of Gunn diodes, slot line resonators and microstrip lines. By embedding Gunn diodes on the slot line resonators, the harmonic RF signal can be generated very easily. The microstrip lines are used for the power combining output circuit. This oscillator has advantages such as easy circuit design, simple circuit configuration and miniaturization of the circuit size. The second harmonic oscillator is designed and fabricated in K-Band. The output power is +5.75 dBm at the design frequency of 19.0 GHz (2f0) with the phase noise of -111.7 dBc/Hz at the offset frequency of 1 MHz. Excellent suppression of the undesired fundamental frequency signal (f0) of -39 dBc is achieved.

The frequency of a pattern may not be a sufficient criterion for identifying meaningful patterns in a database. The temporal regularity of a pattern can be another key criterion for assessing the importance of a pattern in several applications. A pattern can be said regular if it appears at a regular user-defined interval in the database. Even though there have been some efforts to discover periodic patterns in time-series and sequential data, none of the existing studies have provided an appropriate method for discovering the patterns that occur regularly in a transactional database. Therefore, in this paper, we introduce a novel concept of mining regular patterns from transactional databases. We also devise an efficient tree-based data structure, called a Regular Pattern tree (RP-tree in short), that captures the database contents in a highly compact manner and enables a pattern growth-based mining technique to generate the complete set of regular patterns in a database for a user-defined regularity threshold. Our performance study shows that mining regular patterns with an RP-tree is time and memory efficient, as well as highly scalable.

We propose to integrate a single lens on top of multiple OLEDs. Angular distribution of the light emitted from the lens surface is altered by turning on the OLEDs selectively. We can use such a light source as a backlight for a liquid crystal display to switch its viewing angle range and/or to display multiple images in different directions. Pixel-level integration would allow one to construct an OLED display with a similar emission angle control.

Simulation and fabrication results on back-illuminated 4-channel photodiode (PD) array with a self-aligned micro ball lens are described. The channel pitch and diameter of each photosensitive area are 250 µm and 40 µm, respectively. Measured photocurrent is 1.92 times larger than that without a lens. Alignment tolerance between the single mode fiber (SMF) optical axis and the photodiode is improved from 21.2 µm to 42.7 µm. Moreover, the separation tolerance between the fiber and the lens is 210.5 µm. These large tolerances agree with simulation results, demonstrating that the device configuration is suitable for receivers for multi-channel inter-connection. Frequency response and inter-channel cross talk are also discussed.

This paper studies the rotation map with a controlling segment. As a parameter varies, the map exhibits superstable periodic orbits, chaos and rich bifurcation phenomena. The map is applicable to an A/D converter having efficient resolution characteristics. The converter can be realized as a circuit model based on a spiking neuron and the rate-coding. Presenting a test circuit, basic operation is confirmed experimentally.

Monolithic gyrators are proposed on the basis of integrating resonant tunneling diodes (RTDs) and HEMT toward realization of broadband and high-Q passives. Feasibility of millimeter-wave active inductors using the gyrator are described with equivalent circuit analysis and numerical calculations assuming InP based RTDs and a HEMT to be integrated.

An exact computable expression is obtained for the electromagnetic field of a three-dimensional partially finite periodic array of lossless or lossy magnetodielectric spheres illuminated by a plane wave propagating parallel to the array axis. The array is finite in the direction of the array axis and is of infinite extent in the directions transverse to the array axis. Illustrative numerical examples are presented.

This paper presents a new quarter-wavelength microstrip coupler compensated with a periodic sequence of floating metallic strips in the slots on the inner edges. After describing the characteristics of the coupled-line, as an example, a 15-dB coupler is designed and a high directivity of 30 dB or more in theory is obtained over a full band of a single-section coupler. Next, couplers with various coupling factors are designed, and the usefulness for very loose coupling is demonstrated. Furthermore, a three-section coupler is designed to show the effectiveness in a wide frequency range. The validity of the design concept and procedure is confirmed by electromagnetic simulations and experiments.

We studied planar graded-gap injector GaAs Gunn diodes designed for operation at 94 GHz. Two types of planar Gunn diodes were designed and fabricated. In the first diode, a cathode was situated inside a circular anode with a diameter of 190 µm. The distance between the anode and cathode varied from 60 µm to 68 µm depending on the cathode size. Also, we designed a structure with a constant distance between the anode and cathode of 10 µm. In the second diode, the anode was situated inside the cathode for the flip-chip mounting on the oscillator circuits. The fabrication of the Gunn diode was based on ohmic contact metallization, mesa etching, and air-bridge and overlay metallization. DC measurements were carried out, and the nature of the negative differential resistance, the operating voltage, and the peak current in the graded-gap injector GaAs Gunn diodes are discussed for different device structures. It is shown that the structure with the shorter distance between the cathode and anode has a higher peak current, higher breakdown voltage, and lower threshold voltage than those of the structure with the larger distance between the cathode and anode.

This paper considers numerical methods for stability analyses of periodic solutions of ordinary differential equations. Stability of a periodic solution can be determined by the corresponding monodromy matrix and its eigenvalues. Some commonly used numerical methods can produce inaccurate results of them in some cases, for example, near bifurcation points or when one of the eigenvalues is very large or very small. This work proposes a numerical method using a periodic boundary condition for vector fields, which preserves a critical property of the monodromy matrix. Numerical examples demonstrate effectiveness and a drawback of this method.

This paper shows a necessary condition for type- and Gauss period normal bases in Fpm to be the same normal basis by using their traces.

Space-time block codes (STBCs) from coordinate interleaved orthogonal designs (CIODs) have attracted a great deal of attention due to their full-diversity and linear maximum likelihood (ML) decodability. In this letter, we propose a simple detection technique, particularly for full-rate STBCs from CIODs to overcome the performance degradation caused by time-selective fading channels. Furthermore, we evaluate the effects of time-selective fading channels and imperfect channel estimation on STBCs from CIODs by using a newly-introduced index, the results of which demonstrate that full-rate STBCs from CIODs are more robust against time-selective fading channels than conventional full-rate STBCs.

This study proposes a method to decompose a signal into a set of periodic signals. The proposed decomposition method imposes a penalty on the resultant periodic subsignals in order to improve the sparsity of decomposition and avoid the overestimation of periods. This penalty is defined as the weighted sum of the l2 norms of the resultant periodic subsignals. This decomposition is approximated by an unconstrained minimization problem. In order to solve this problem, a relaxation algorithm is applied. In the experiments, decomposition results are presented to demonstrate the simultaneous detection of periods and waveforms hidden in signal mixtures.

A radio-on-dense-wavelength-division-multiplexing (DWDM) transport system based on injection-locked Fabry-Perot laser diodes (FP LDs) with four microwave carriers and large effective area fiber (LEAF) transmission was proposed and demonstrated. Good performance of bit error rate (BER) and intermodulation distortion to carrier ratio (IMD/C) over a-50 km of LEAF was obtained. Signal quality meets the demands of personal handy system (PHS)/vehicle information and communication system (VICS)/electronic toll collection (ETC)/satellite broadcasting (SB).

Si-based photonic materials and devices, including SiGe/Si quantum structures, SOI and InGaAs bonded on Si, PL of Si nanocrystals, SOI photonic crystal filter, Si based RCE (Resonant Cavity Enhanced) photodiodes, SOI TO (thermai-optical) switch matrix were investigated in Institute of Semiconductors, Chinese Academy of Sciences. The main results in recent years are presented in the paper. The mechanism of PL from Si NCs embedded in SiO2 matrix was studied, a greater contribution of the interface state recombination (PL peak in 850~900 nm) is associated with larger Si NCs and higher interface state density. Ge dots with density of order of 1011 cm-2 were obtained by UHV/CVD growth and 193 nm excimer laser annealing. SOI photonic crystal filter with resonant wavelength of 1598 nm and Q factor of 1140 was designed and made. Si based hybrid InGaAs RCE PD with η of 34.4% and FWHM of 27 nm were achieved by MOCVD growth and bonding technology between InGaAs epitaxial and Si wafers. A 1616 SOI optical switch matrix were designed and made. A new current driving circuit was used to improve the response speed of a 44 SOI rearrangeable nonblocking TO switch matrix, rising and falling time is 970 and 750 ns, respectively.