Output feedback decoupling of multivariable systems

Necessary and sufficient conditions for output feedback decoupilng of linear time-invariant multivariable systems into single input-multioutput subsystems are derived in frequency domain. The conditions imply a new constructive method for determining a constant gain output feedback matrix and some of its elements can be freely chosen to reassign the closed-loop poles.     

Effects of diffuser shape and back pressure on the performance of disk MHD generators

The effects of diffuser shape and back pressure on the performance of closed‐cycle disk MHD generators are investigated with two‐dimensional numerical simulations taking account of the boundary layer. The enthalpy extraction ratio decreases and fluctuates periodically with increase in the back pressure. The amplitude of power output fluctuation and the period depend on the volume of the inverse flow region. For the reduced height diffuser, the inverse flow region is suppressed and the fluctuation becomes smaller than that for the constant height diffuser. When operated with a back pressure lower than an optimum value, the diffuser does not work because of reacceleration in the diffuser. For the higher back pressure, on the contrary, the inverse flow region propagates into the MHD channel, then the enthalpy extraction ratio is reduced and the Mach number at the exit of the MHD channel becomes lower than unity. For the optimum back pressure, high enthalpy extraction ratio is achieved and the adiabatic efficiency at the diffuser exit is decreased by several percent from that evaluated at the MHD channel exit. © 2000 Scripta Technica, Electr Eng Jpn, 133(2): 11–19, 2000     

Rule Construction and Execution for Root Cause Analysis

We developed a root cause analysis (RCA) system for an enterprise IT system environment. In this paper, we propose a rule‐construction method that builds analysis rule data objects from general analysis rules and the topology information of the actual target IT environment. Using this method, the IT administrator can use the RCA system without any manual rule modifications. For the execution of the analysis, we introduce the certainty factor to realize robust analysis when the order and reachability of a fault event cannot be guaranteed.     

Morphological and Genetic Diversities of Habenaria radiata (Orchidaceae) in the Kinki Area,Japan

Floral organs have evolved from leaves for reproduction, and the morphological analyses help to understand the plant diversity and evolution. Habenaria radiata (syn. Pecteilis radiata) is a terrestrial orchid living in wetlands in Japan, Russia, South Korea, and China. The habitats of this plant in Japan have been reduced because of environmental destruction and overexploitation, and thus it is on the Red List of Japan as a Near Threatened species. One of the three petals of the H. radiata flower is called a lip or labellum, which resembles a flying white bird, egret, or white heron, with its proposed function being to attract pollinators. To understand the diversity of H. radiata plants in different areas, we examined the lip morphology and phylogeny of populations from eight habitats in the Kinki area, Japan. The complex shapes of the lips were quantified and presented as a radar chart, enabling characterization of the morphological difference among populations. Phylogenetic analysis with microsatellite markers that we generated showed the variation of genetic diversity among populations, suggesting the different degrees of inbreeding, outbreeding, and vegetative propagation. Our approach offers a basic method to characterize the morphological and genetic diversity in natural populations.     

Inversion domain network stabilization and spinel phase suppression in ZnO

The development of inversion domain networks consisting of basal‐plane and pyramidal‐plane inversion domain boundary (b‐IDB and p‐IDB) interfaces within grains in Sn‐Al dual‐doped ZnO (Zn_0.98Sn_0.01Al_0.01O) polycrystalline ceramics has been confirmed using transmission electron microscopy. The atomic structure of the b‐IDB and p‐IDB interfaces has been analyzed using atomic‐resolution scanning transmission electron microscopy. The localization of Sn and Al at the respective sites of the b‐IDBs and p‐IDBs was confirmed by energy‐dispersive X‐ray spectroscopy. In contrast to Sn or Al single‐dopant addition to ZnO, which results in the formation of spinel phase precipitates without the development of inversion domain networks, Sn‐Al dual‐doping caused the suppression of spinel phase formation and the formation of monophasic inversion domain networks composed of RMO₃(ZnO)_n homologous phase compound members, where R and M represent dopants substituting at the b‐IDB and p‐IDB sites, with a general formula of SnAlO₃(ZnO)_n. The results of this study demonstrate that the formation of inversion domain networks in ZnO‐based ceramics can be stabilized via multiple‐dopant addition. This finding has potential implications for the modification of the bulk or nanoscale properties based on the choice of the specific dopants, R and M, the control of the ratio R:M and the value of n in the RMO₃(ZnO)_n homologous phase compound members constituting the inversion domain networks.     

Electronic Structures of Two-Phase Microstructures in Pb-doped Bi2Sr2CaCu2O y

We have performed scanning tunneling microscopy/spectroscopy (STM/STS) on single crystals of heavily Pb-doped Bi ₂ Sr ₂ CaCu ₂ O _y (Pb-Bi2212). The obtained STM images clearly demonstrated phase separation into the and phases with lamella-type and new zigzag-like microstructures. From the site-specified tunneling measurements, it was directly confirmed that the phase possesses higher T _c . This suggests that the phase boundaries act as strong pinning sites especially at higher temperatures.     

Numerical Verifications of Solutions for Nonlinear Parabolic Equations in One-Space Dimensional Case

In this paper, we describe a numerical method to verify the solutions with guaranteed error bounds for nonlinear parabolic problems in one dimensional case. It is based on Plum's method for formulating the problem and weak formulation for estimating explicitly the inverse norm of the linearized operator. We introduce some weighted norms on time-dependent Sobolev spaces, which play an important role in the application of our method. We present detailed verification procedures by using this weighted norm and show some numerical examples.     

Socially inspired search and ranking in mobile social networking: concepts and challenges

In this paper, we provide an overview of challenges in mobile search and ranking, and envision the fundamental features that should be satisfied. We argue that two principles will help improve the relevance and quality of mobile search and ranking: the first one is to examine both intrinsic content features and context of items (usage statistics and social features, etc.); and the second one lies in that no algorithms can replace the objectivity of a human being—let users define the sites that they feel are relevant, leverage their social networks, and over time see their results become highly personalized. Specifically, wireless-virtualcommunity-based mobile search and ranking architecture is proposed in this paper, in which communities act as a first class abstraction for information sharing. Then, we introduce briefly the potential procedures of achieving high relevance and quality in mobile search and ranking based on wireless virtual community.     

Curvature continuous path generation for autonomous vehicle using B-spline curves

In this paper we introduce a roadmap algorithm for generating collision-free paths in terms of cubic B-spline curves for unmanned vehicles used in mining operations. The algorithm automatically generates collision-free paths that are curvature continuous with an upper bounded curvature and a small slope discontinuity of curvature at knots, when we are given the locations of the obstacles, the boundary geometry of the working area, positions and directions of the vehicle at the start, loading, and the goal points. Our algorithm also allows us to find a switch back point where the vehicle reverses its direction to enter the loading area. Examples are provided to demonstrate the effectiveness of the proposed algorithms.