Search

Raman scattering spectra of the ferroelectric KDP (KH2PO4) have been observed under hydrostatic pressure up to 52.0 kbar using a diamond anvil cell at room temperature. A curious dispersion relation of the soft mode at the Γ point of the Brillouin zone is derived from the low-frequency components of the B2(z) spectra in z(yx)z + δ and x(yx)y geometries after numerical fitting based on the coupled phonon model. The dispersion relation suggests breakdown of the soft-mode model of KDP. Each of the frequencies of the internal v1, v2 and v3 modes of the PO4 ion show a linear dependence on pressure with the mode Gruneisen parameter, 0.32, 0.31 and a small value of 2.5 × 10−2, respectively. Increase of the frequencies of the v1 and v2 modes corresponds to pressure dependence of the P–O distance. A new pressure-induced phase transition appears at 40.0 kbar with a growing relaxational central peak in the spectra.

It is very useful to control fluid actuator by means of various inputs to apply for wide applications. Especially if we can control the actuator by optical method, wide application of that is considered in optical micro-machine. Fluidic device controlled by light have investigated, however these are dealt in micro- or nano- world. This investigation pioneers control method of normal size fluidic actuator by means of radiation pressure of light as inputs.

A fuzzy c-means (FCM) classifier derived from a generalized FCM clustering is proposed. The classifier design is based on FCM. The classifier is not initialized with random numbers, hence being deterministic. The parameters are optimized by cross validation (CV) protocol and golden section search method. A method for dealing with missing values without eliminating them but with estimating them is also proposed. Instead of using the terminology "conditional expectation", the imputation is done by the least square method of Mahalanobis distances between the datum with missing values and cluster centers. The FCM classifier outperforms well established methods such as support vector machine, k-nearest neighbor and Gaussian mixture classifiers for datasets with and without missing values

In this research, a dialog environment between human and virtual agent has been constructed. With the commercial off-the-shelf VR technologies, special devices such as data glove have to be used for the interaction. But this is difficult to manipulate objects. If there is a helper who has direct access to objects in a virtual space, we may ask him. The question, however, is how to communicate with the helper. This paper presents a solution to the question. The basic idea is to utilize speech recognition and gesture recognition systems. Experimental results have proved the effectiveness of the approach in terms of facilitating man-machine interaction and communication. The environment constructed in this research allows a user to communicate by talking and showing gestures to a personified agent in virtual environment. A user can use his/her finger to point at a virtual object and ask the agent to manipulate the virtual object.

We investigated preferable way of decrease of vertical leakage current in GaN-based high-electron-mobility-transistor structure on Si(111) substrate. It is found that the leakage current is much improved as the dislocation density in thin A1N buffer layer decreases. It has been successfully obtained the leakage current less than 10-4 A/cm2 at 200 V although the total epitaxial layer thickness is about only 1 mum.

The rigid bodies-spring model (RBSM) has been developed as a numerical model to generalize limit analysis in plasticity, in which the structure to be analyzed is idealized as an assemblage of rigid bodies connected by normal and tangential springs. Originally, this approach was a discrete model for handling static problem. In this paper, we illustrate the formulation of an explicit dynamic method for each element using the principle of hybrid-type virtual work. Additionally, we propose a new RBSM approach for contact mechanism and friction characteristics. Finally, we verify the accuracy of dynamic analysis by RBSM with some numerical examples.

Unexpected trauma is a one of the most major causes of death for children in the world. However, pediatric severe trauma patients are rare and scattered. Although there is a strong association between patient's volume of trauma center volume and outcomes in adults, such a report is less in children. In this study, we aimed to clarify the relationship of the amount of registration and outcome in pediatric trauma patients.

We successfully fabricated high-quality InAlN/GaN heterostructures for high electron mobility transistors (HEMTs) on Si (111) substrate by metalorganic chemical vapor deposition (MOCVD). X-ray diffraction measurements revealed that InAlN/GaN heterostructures grown under optimal conditions have a flat surface and an abrupt heterointerface. The surface roughness evaluated from atomic force microscopy (AFM) is improved, compared with previous reports. Electron mobility of about 1,200 and over 1,800 cm2/V·s are obtained for InAlN/GaN heterostructures without and with an AlN interlayer, respectively. These mobility values are the highest ones ever reported for InAlN/GaN heterostructures grown on Si substrates.

In this research, a dialog environment between human and virtual environment has been constructed. At preset, if a person wants to interact with virtual environment, special device such a data glove is required, but it makes difficult for general users to manipulate virtual objects. When we cannot manipulate objects directly, it is natural that we ask someone with a privilege to do the operation in place of us. In the case, it is convenient if methods used in daily life are allowed. That is, the method to be proposed here is based on the integration between verbal information through the utterances and non-verbal information by the gestures such as finger pointing. The experimental results have proved the effectiveness of this approach in terms of facilitating man-machine interaction and communication. The environment constructed in this research allows a user to communicate by talking and showing gestures to a personified agent in virtual environment. A user can use his/her finger to point at a virtual object and ask him to manipulate it

We report the measurement and calculation results of a laser beam spot distortion caused by dynamic deformation of a MEMS scanning mirror. The laser beam spot distortion is measured by using the CCD camera located on focal point when an emission timing of the laser beam is synchronized with a motion of the scanning mirror. The calculated distortion is simulated by using the Fresnel-Kirchhoff diffraction formula. A dynamic deformation of the mirror is calculated by FEM. Their results have showed good agreement. Therefore we have proved our calculation method available

We review our recent results on optical short pulse generation based on "comb-like profiled fiber (CPF)". Various types of CPF are summarized, where we show that the CPF technologies are suitable for truly practical, externally synchronous, and flexible short pulse generation.

The ${E}_{u}$ mode of the isotope-induced ferroelectric strontium titanate ${\mathrm{SrTi}}^{18}{\mathrm{O}}_{3}$ shows a perfect softening at the ferroelectric phase transition temperature ${T}_{c}$, where the frequency of the underdamped mode approaches completely to zero within the instrumental resolution. The spectra of the Raman inactive soft ${E}_{u}$ mode have been successfully observed owing to local symmetry breaking and by long-term accumulation of the spectral intensity with a high resolution technique. The mechanism of the phase transition is concluded to be an ideal displacive-type accompanied with perfect softening of the Slater-type polar ${E}_{u}$ mode. The difference between the soft mode behavior of $\mathrm{SrTi}^{16}\mathrm{O}_{3}$ and $\mathrm{SrTi}^{18}\mathrm{O}_{3}$ indicates that the origin of the quantum paraelectric state of $\mathrm{SrTi}^{16}\mathrm{O}_{3}$ lies in the quantum fluctuation of the oxide octahedron in the perovskite structure.