1,980 research outputs found
Version Spaces and Generalized Monotone Boolean Functions
We consider generalized monotone functions f: X --> {0,1}defined for an arbitrary binary relationoperations research;ordinal classification;artificial intelligence;machine learning;partially defined Boolean functions
Minimal representations of some classes of dynamic programming
It is known that various discrete optimization problems can be represented by finite state models called sequential decision processes (sdp's). A subclass of sdp's, the class of monotone sdp's (msdp's), is particularly important since the method of dynamic programming is applicable to obtain optimal policies. Several subclasses of msdp's have also been introduced from the viewpoint of computational complexity for obtaining optimal policies. For each of these classes of sdp's, optimal policies are usually obtained (if possible at all) in fewer steps if a given optimization problem is represented by a model with fewer states.Thus we are naturally led to the problem of finding a minimal (with the fewest states) representation of a given optimization problem by an sdp of a specified class. This paper investigates the existence or nonexistence of such minimization algorithms (in the sense of the theory of computation) for various classes of sdp's. It is shown that there exist minimization algorithms for some classes of sdp's, but there exist no algorithms for others.The nonuniqueness of a minimal representation is also proved for each class of sdp's
Theoretical approach to obtaining dynamic characteristics of noncontacting spiral-grooved seals
The dynamic characteristics of spiral-grooved seals are theoretically obtained by using the Navier-Stokes equation. First, with the inertia term of the fluid considered, the flow and pressure in the steady state are obtained for the directions parallel to and perpendicular to the groove. Next, the dynamic character is obtained by analyzing the steady state and by analyzing the labyrinth seal. As a result, the following conclusions were drawn: (1) As the land width becomes shorter or the helix angle decreases, the cross-coupling stiffness, direct and cross-coupling damping, and add mass coefficients decrease; (2) As the axial Reynolds number increases, the stiffness and damping coefficients increase. But the add mass coefficient is not influenced by the axial Reynolds number; (3) The rotational Reynolds number influences greatly the direct and cross-coupling stiffness and direct damping coefficients; and (4) As the journal rotating frequency increases, the leakage flow decreases. Therefore zero net leakage flow is possible at a particular rotating frequency
Static and dynamic characteristics of parallel-grooved seals
Presented is an analytical method to determine static and dynamic characteristics of annular parallel-grooved seals. The governing equations were derived by using the turbulent lubrication theory based on the law of fluid friction. Linear zero- and first-order perturbation equations of the governing equations were developed, and these equations were analytically investigated to obtain the reaction force of the seals. An analysis is presented that calculates the leakage flow rate, the torque loss, and the rotordynamic coefficients for parallel-grooved seals. To demonstrate this analysis, we show the effect of changing number of stages, land and groove width, and inlet swirl on stability of the boiler feed water pump seals. Generally, as the number of stages increased or the grooves became wider, the leakage flow rate and rotor-dynamic coefficients decreased and the torque loss increased
Suzaku observations of the low surface brightness cluster A76
Context: We present results of Suzaku observations of a nearby galaxy cluster
A76 at z=0.0395. This cluster is characterized by extremely low X-ray surface
brightness and is hereafter referred to as the LSB cluster. Aims: To understand
the nature and thermodynamic evolution of the LSB cluster by studying the
physical properties of the hot intracluster medium in A76. Methods: We
conducted two-pointed Suzaku observations of A76 and examined the global gas
properties of the cluster by XIS spectral analysis. We also performed
deprojection analysis of annular spectra and derived radial profiles of gas
temperature, density and entropy out to approximately 850 kpc (~ 0.6 r_200) and
560 kpc (~0.4 r_200) in A76 East and A76 West, respectively. Results: The
measured global temperature and metal abundance are approximately 3.3 keV and
0.24 solar, respectively. From the deprojection analysis, the entropy profile
is found to be flat with respect to radius. The entropy within the central
region (r < 0.2r_200) is exceptionally high (~400 keV cm^2). This phenomenon is
not readily explained by either gravitational heating or preheating. The X-ray
morphology is clumped and irregular, and the electron density is extremely low
(1e-4 -- 1e-3 cm^-3) for the observed high temperature, suggesting that A76 is
in the early phase of cluster formation and the gas compression due to
gravitational potential confinement is lagging behind the gas heating.Comment: 7 pages, 5 figures, A&A accepte
Suzaku study of gas properties along filaments of A2744
Context: We present the results of Suzaku observations of a massive galaxy
cluster A2744, which is an active merger at . Aims: By using long
X-ray observations of A2744, we aim to understand the growth of the cluster and
the gas heating process through mass accretion along the surrounding filaments.
Methods: We analyzed data from two-pointed Suzaku observations of A2744 to
derive the temperature distribution out to the virial radius in three different
directions. We also performed a deprojection analysis to study radial profiles
of gas temperature, density, and entropy and compared the X-ray results with
multi-wavelength data to investigate correlations with the surface density of
galaxies and with radio relics. Results: The gas temperature was measured out
to the virial radius in the north-east region and to about
in the north-west and south regions. The radial profile of the gas
temperature is rather flat and the temperature is very high (even near
); it is comparable to the mean temperature of this cluster (
keV). These characteristics have not been reported in any other cluster. We
find a hint of temperature jump in the northeast region whose location
coincides with a large radio relic, indicating that the cluster experienced gas
heating because of merger or mass accretion onto the main cluster. The
temperature distribution is anisotropic and shows no clear positive correlation
with the galaxy density, which suggests an inhomogeneous mass structure and a
complex merger history in A2744.Comment: 8 pages, 8 figures, A&A accepte
Research Trends toward Cooperation and Collaboration in School Support Systems of Pupil and Student : Through the Perspective of School Psychology and Pedagogy
This study is an overview of the developments in interdepartmental cooperation and
interdisciplinary collaboration between school systems and also between counselors
and non-teaching staff at the elementary, junior high and high school levels from a
psychological and pedagogical perspective. Strategies under examination will include
cooperation between management and also between technical and non-teaching staff,
school system development, establishing and maintaining a cooperative mood and
building a communicative spirit at school. In addition, we will look at majors and
specializations of non-teaching staff and leadership qualitative of principals (and head
masters).Few researchers have emphasized the combined study of school management
and psychology. In this paper, I hope to highlight more ideas related to the specializations
of staff as a parameter of systematized cooperation
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