The Volterra filter is one of the digital filters that can describe nonlinearity. In this paper, we analyze the dynamic behaviors of an adaptive signal processing system with the Volterra filter for nonwhite input signals by a statistical-mechanical method. Assuming the self-averaging property with an infinitely long tapped-delay line, we derive simultaneous differential equations that describe the behaviors of macroscopic variables in a deterministic and closed form. We analytically solve the derived equations to reveal the effect of the nonwhiteness of the input signal on the adaptation process. The results for the second-order Volterra filter show that the nonwhiteness decreases the mean-square error (MSE) in the early stages of the adaptation process and increases the MSE in the later stages.

Incorporating a tool for administering medication, such as a syringe, is required in microneedles (MNs) for medical use. This renders it easier for non-medical personnel to administer medication. Because it is difficult to fabricate a hollow MN, we fabricated a capillary groove on an MN and its substrate to enable the administration of a higher dosage. MN grooving is difficult to accomplish via the conventional injection molding method used for polylactic acid. Therefore, biodegradable polyacid anhydride was selected as the material for the MN. Because polyacid anhydride is a low-viscosity liquid at room temperature, an MN can be grooved using a processing method similar to vacuum casting. This study investigated the performance of the capillary force of the MN and the optimum shape and size of the MN by a puncture test.

The Volterra filter is one of the digital filters that can describe nonlinearity. In this paper, we analyze the dynamic behaviors of an adaptive signal-processing system including the Volterra filter by a statistical-mechanical method. On the basis of the self-averaging property that holds when the tapped delay line is assumed to be infinitely long, we derive simultaneous differential equations in a deterministic and closed form, which describe the behaviors of macroscopic variables. We obtain the exact solution by solving the equations analytically. In addition, the validity of the theory derived is confirmed by comparison with numerical simulations.

The interval in ℕ composed of finite states of the stream version of asymmetric binary systems (ABS) is irreducible if it admits an irreducible finite-state Markov chain. We say that the stream version of ABS is irreducible if its interval is irreducible. Duda gave a necessary condition for the interval to be irreducible. For a probability vector (p,1-p), we assume that p is irrational. Then, we give a necessary and sufficient condition for the interval to be irreducible. The obtained conditions imply that, for a sufficiently small ε, if p∈(1/2,1/2+ε), then the stream version of ABS could not be practically irreducible.

In this study, we examined the mechanical durability and self-recovery characterization of liquid crystal gel films with lysine-based gelator. The results indicated that the structural destruction in liquid crystal gel films is attributed to dissociation among network structure. The cracked LC gel films can be recovered by formation of sol-sate films.

The electric properties of a field-effect transistor not only depend on gate surface sidewall but also on channel orientation when applying channel stain engineering. The change of the gate surface and channel orientation through the rotated FinFETs provides the capability to compare the orientation dependence of performance and reliability. This study characterized the <100> and <110> channels of FinFETs on the same wafer under tensile and compressive stresses by cutting the wafer into rectangular silicon pieces and evaluated their piezoresistance coefficients. The piezoresistance coefficients of the <100> and <110> silicon under tensile and compressive stresses were first evaluated based on the current setup. Tensile stresses enhance the mobilities of both <100> and <110> channels, whereas compressive stresses degrade them. Electrical characterization revealed that the threshold voltage variation and drive current degradation of the {100} surface were significantly higher than those of {110} for positive bias temperature instability and hot carrier injection with equal gate and drain voltage (VG=VD). By contrast, insignificant difference is noted for the subthreshold slope degradation. These findings imply that a higher ratio of bulk defect trapping is generated by gate voltage on the <100> surface than that on the <110> surface.

We analyze the behaviors of the FXLMS algorithm using a statistical-mechanical method. The cross-correlation between a primary path and an adaptive filter and the autocorrelation of the adaptive filter are treated as macroscopic variables. We obtain simultaneous differential equations that describe the dynamical behaviors of the macroscopic variables under the condition that the tapped-delay line is sufficiently long. The obtained equations are deterministic and closed-form. We analytically solve the equations to obtain the correlations and finally compute the mean-square error. The obtained theory can quantitatively predict the behaviors of computer simulations including the cases of both not only white but also nonwhite reference signals. The theory also gives the upper limit of the step size in the FXLMS algorithm.

We experimentally investigate and analyze faults in optical fiber connections with refractive index matching material that have incorrectly cleaved fiber ends. We explain that incorrectly cleaved fiber ends, which are not ideal because they are uneven and not perpendicular to the fiber axis, are caused by defective optical fiber cleavers. We discover that the optical performance of field installable connections using incorrectly cleaved fiber ends might change greatly. We also infer that the significant change in insertion and return losses might be attributed to partially air-filled gaps by using scatter diagrams of measured insertion and return losses. Our experiment results reveal that the optical performance might deteriorate to more than 40dB in terms of insertion loss and less than 30dB in terms of return loss.

A modified modeling of residue effect on nano-electro-mechanical nonvolatile memory (NEMory) is presented for considering wet etching process. The effect of a residue under the cantilever is investigated for the optimization. The feasibility of the proposed model is investigated by finite element analysis simulations.

The fringe field effects of nano-electromechanical (NEM) nonvolatile memory cells have been investigated analytically for the accurate evaluation of NEM memory cells. As the beam width is scaled down, fringe field effect becomes more severe. It has been observed that pull-in, release and hysteresis voltage decrease more than our prediction. Also, the fringe field on cell characteristics has been discussed.

This paper presents a highly efficient multi-band power amplifier (PA) with a novel reconfigurable configuration. It consists of band-switchable matching networks (BS-MNs) and a biasing network (BS-BN) that are available for multi-band operation. BS-MNs with a susceptance block (SB) require a shorter transmission line (TL) than those without the SB at some target impedances. This paper theoretically derives the relationships of the required TL lengths for the BS-MN with or without the SB and the target impedances. The required TL lengths at the target impedances are evaluated numerically in order to discuss the advantages of the proposed configuration. The BS-BN employing switches for band switching can supply DC power to an amplification device without additional DC power dissipation because the DC bias current does not flow through the switches. Numerical analyses confirm that a BS-BN can be configured with low loss in multiple bands. Based on the proposed configuration, a 1/1.5/1.9/2.5-GHz quad-band reconfigurable PA is designed and fabricated employing RF microelectro mechanical systems switches and partitioned low temperature co-fired ceramics substrates. The fabricated 1 W-class PA achieves a high output power of greater than 30 dBm and a maximum power added efficiency of over 40% in all operating modes.

We show that simultaneous perturbation can be used as an algorithm for on-line learning, and we report our theoretical investigation on generalization performance obtained with a statistical mechanical method. Asymptotic behavior of generalization error using this algorithm is on the order of t to the minus one-third power, where t is the learning time or the number of learning examples. This order is the same as that using well-known perceptron learning.

A new in vitro experimental tool was developed to study the mechanism of the ultrasonic closing clicks' genesis of mechanical heart valves. Since the newly developed tester adopted compressed air flow directly instead of the blood analog fluid to drive the mechanical heart valve, it is not possibe to generate any cavitation. Closing clicks were measured with a small accelerometer at the surface of the valve holder made of silicone rubber. Ultrasonic closing clicks as well as audible closing clicks, similar to those measured clinically, could be observed using this setup. Thus, it was confirmed that the ultrasonic closing clicks can be generated without the existence of cavitation. Simultaneous measurements of the valve motion were made with a high-speed video camera, and the analysis of the video frames and clicks showed that higher frequency signal components of more than 50 kHz could be generated only at the instant of the closure, which means the collision of the occluder with the housing. Eighteen miniature accelerometers with an area of one square millimeter were developed and stuck on the housing to monitor the distribution of the housing vibrations in detail, and it was found that the vibrations correspond to the ultrasonic closing clicks propagated from the valve stop: the collision point of the occluder with the housing. This fact indicated that the generation of ultrasonic closing clicks are limited to the small area of the collision. From those results, it was concluded that the major origin of the ultrasonic closing clicks' genesis should be the collision of the occluder with the housing.

The electrostatic force required for the driving of liquid droplet injected in a microchannel was studied to obtain the guiding principle to reduce the driving voltage of waveguide optical switch based on the movement of droplet. We analytically calculated the relation between the threshold voltage and velocity of droplet and the surface roughness of microchannel, and clarified some unconfirmed parameters by comparing experimental results and aeromechanical analysis. The driving of droplet in a microchannel was best analyzed using the Hagen-Poiseuille flow theory, taking into account the movement of both ends of the droplet. When the droplet is driven by some external force, a threshold of the external force occurs in the starting of movement, and hysteresis occurs in the contact angle of the droplet to the side wall of the microchannel. The hysteresis of contact angle is caused by the roughness of side wall. In our experiment, the threshold voltage ranged from 200 to 350 V and the switching time from 34 to 36 ms. The velocity of droplet was evaluated to be 0.3-0.4 mm/s from these experimental results. On the other hand, the measured angle distribution of side wall roughness ranged from 30 to 110 degrees, and the threshold voltage was evaluated to be 100-320 V, showing a good agreement with experimental results. The reduction of threshold voltage can be realized by smoothing the side wall roughness of microchannel. The switching time of 10 ms, which is required for the optical stream switch, can be obtained by shortening the horizontal spot size down to 1.5 µm.

In this paper we analytically investigate the generalization performance of learning using correlated inputs in the framework of on-line learning with a statistical mechanical method. We consider a model composed of linear perceptrons with Gaussian noise. First, we analyze the case of the gradient method. We analytically clarify that the larger the correlation among inputs is or the larger the number of inputs is, the stricter the condition the learning rate should satisfy is, and the slower the learning speed is. Second, we treat the block orthogonal projection learning as an alternative learning rule and derive the theory. In a noiseless case, the learning speed does not depend on the correlation and is proportional to the number of inputs used in an update. The learning speed is identical to that of the gradient method with uncorrelated inputs. On the other hand, when there is noise, the larger the correlation among inputs is, the slower the learning speed is and the larger the residual generalization error is.

A new type of algorithm for predicting the mechanical faults of a vacuum circuit breaker (VCB) based on an artificial neural network (ANN) is proposed in this paper. There are two types of mechanical faults in a VCB: operation mechanism faults and tripping circuit faults. An angle displacement sensor is used to measure the main axle angle displacement which reflects the displacement of the moving contact, to obtain the state of the operation mechanism in the VCB, while a Hall current sensor is used to measure the trip coil current, which reflects the operation state of the tripping circuit. Then an ANN prediction algorithm based on a sliding time window is proposed in this paper and successfully used to predict mechanical faults in a VCB. The research results in this paper provide a theoretical basis for the realization of online monitoring and fault diagnosis of a VCB.

This paper describes a beam scanning antenna that consists of a movable dielectric plate loaded onto a microstrip comb-line antenna. This type of antenna uses a mechanical system and so offers a simple structure and low cost. The main beam direction of the proposed antenna is changed by moving the dielectric plate. The guide wavelength of the microstrip line was measured at the quasi-millimeter wave band (20 GHz) when moving the dielectric plate to investigate the possibility of beam scanning. The proposed antenna was fabricated to experimentally demonstrate its principle operation. A possible beam scanning angle of 20 degrees was confirmed.

We propose and demonstrate a new fabrication process of a microchannel using the Damascene process. This process aims to integrate photonic circuits with microchannels fabricated in a glass film. The microchannel is fabricated by the removal of the sacrificial layer after a sacrificial layer is formed by the Damascene process and the cover is formed by sputter deposition. A thin cover layer can be formed by the sacrificial method, because the cover layer is supported by the sacrificial layer during film formation. The cover layer is hermetically sealed, since it is formed by radio frequency (RF) sputtering deposition. The thickness is 1 µm and the width ranges from 3.5 to 8 µm. Using the proposed microchannel fabrication method, we prepared a microelectromechanical system (MEMS) optical switch using microfluidics, and we confirmed its functional operation. This optical switch actuates a minute droplet of liquid injected into the microchannel using Maxwell's stresses. Light propagates straight through the waveguide so that the light passes through the microchannel when the droplet is in the microchannel, but the light rays are completely reflected into a crossed waveguide when the droplet is not in the microchannel. Since this fabrication method uses techniques common to those in the formation of copper wiring in an IC chip, it can be used in the microchannel process.

Our investigation of diamond-like carbon (DLC) nano-springs with a 130 nm spring-section diameter, which were fabricated by focused-ion-beam chemical vapor deposition (FIB-CVD), showed for the first time that nanosprings can be stretched. We observed large displacements of the FIB-CVD nanosprings using in situ optical microscopy; in other words, the nanosprings showed behavior similar to that of macroscale springs. In addition, we investigated the dependence of the spring constant of DLC nanosprings on spring diameter. The spring constants, measured using commercially available cantilevers, ranged from 0.47 to 0.07 N/m. The diameter dependence of spring constant can be accurately expressed by the conventional formula for a coil spring. The estimated shear modulus of the DLC nano-springs was about 70 GPa. This value is very close to the value of conventional coil springs made of steel. Furthermore, we measured the stiffness of a DLC nanospring annealed at 1000 in vacuum. The stiffness was decreased to approximately half of the stiffness of the nanospring without annealing.

The main factor determining for both friction and contact resistance is the true contact area in the contact interface. Contact resistance depends on the size of the true contact area and contaminant films interposed between the contact areas of the interface. Moreover, friction force also depends on the true contact area. In particular, the formation of metallic junctions in the true contact area strongly effects the friction force. Therefore, since both electrical contact and friction force are related to the size of the true contact area, the contact resistance and friction force are considered to be interrelated through true contact areas. For electromechanical devices with sliding contacts such as connector and sliding switches, the contact resistance and friction are important characteristics. In order to obtain low contact resistance, contact load should be higher, but the friction force increases. These are opposite-side problems. In this study, as the contact resistance and friction occur in the same true contact area, the relationship between the contact resistance and friction was expressed in an equation. Moreover, this relationship was examined experimentally on a variety of contact surfaces under different surface conditions.