177 research outputs found
New possibility of the ground state of quarter-filled one-dimensional strongly correlated electronic system interacting with localized spins
We study numerically the ground state properties of the one-dimensional
quarter-filled strongly correlated electronic system interacting
antiferromagnetically with localized spins. It is shown that the
charge-ordered state is significantly stabilized by the introduction of
relatively small coupling with the localized spins. When the coupling becomes
large the spin and charge degrees of freedom behave quite independently and the
ferromagnetism is realized. Moreover, the coexistence of ferromagnetism with
charge order is seen under strong electronic interaction. Our results suggest
that such charge order can be easily controlled by the magnetic field, which
possibly give rise to the giant negative magnetoresistance, and its relation to
phthalocyanine compounds is discussed.Comment: 5pages, 4figure
Synthesis of Adaptive Robust Controllers for a Class of Nonlinear Systems with Input Saturations
This paper deals with a design problem of an adaptive robust controller for a class of nonlinear systems with specified input saturations. For the nonlinear system under consideration, the nonlinearity means unknown perturbations and satisfies the matching condition. In this paper, we show that sufficient conditions for the existence of the proposed adaptive robust controller giving consideration to input saturations are given in terms of linearmatrix inequalities (LMIs). Finally, simple illustrative examples are shown
Performance of the TPC with Micro Pixel Chamber Readout: micro-TPC
Micro-TPC, a time projection chamber(TPC) with micro pixel chamber(-PIC)
readout was developed for the detection of the three-dimensional fine(sub-m
illimeter) tracks of charged particles. We developed a two-dimensional position
sensitive gaseous detector, or the -PIC, with the detection area of
1010 cm and 65536 anode electrodes of 400 m pitch. We
achieved the gas gain of over 10000 without any other multipliers. With the
pipe-line readout system specially developed for the -PIC, we detected
X-rays at the rate as high as 7.7 Mcps. We attached a drift cage with an 8 cm
drift length to the -PIC and developed a micro-TPC. We measured the basic
performances of the micro-TPC and took three-dimensional tracks of electrons.
We also developed a prototype of the MeV gamma-ray imaging detector which is a
hybrid of the micro-TPC and NaI(Tl) scintillators and confirmed its concept by
reconstructing the obtained data.Comment: 6 pages 16 figures, submitted for IEEE/TNS 200
Performance of a micro-TPC for a time-resolved neutron PSD
We report on the performance of a micro-TPC with a micro pixel
chamber(-PIC) readout for a time-resolved neutron position-sensitive
detector(PSD). Three-dimensional tracks and the Bragg curves of protons with
energies of around 1 MeV were clearly detected by the micro-TPC. More than 95%
of gamma-rays of 511 keV were found to be discriminated by simple analysis.
Simulation studies showed that the total track length of proton and triton
emitted from the (n,p(573 keV)) reaction is
about 1.2 cm, and that both particles have large energy losses () in 1 atm Ar++He(). These values
suit the current performance of the micro-TPC, and we conclude that a
time-resolved neutron PSD with spatial resolution of sub-millimeters shall be
developed as an application of the micro-TPC.Comment: 13 pages, 10 figures, to appear in NIM
Robot arm system for automatic satellite capture and berthing
Load control is one of the most important technologies for capturing and berthing free flying satellites by a space robot arm because free flying satellites have different motion rates. The performance of active compliance control techniques depend on the location of the force sensor and the arm's structural compliance. A compliance control technique for the robot arm's structural elasticity and a consideration for an end-effector appropriate for it are presented in this paper
Dirac Electrons in Molecular Solids
Electrons in solids are characterized by the energy bands, which indicate
that electrons are considered to be "elementary particles" with specific
effective masses and g-factors reflecting features of each solid. There are
cases where these particles obey dispersion relationship similar to those of
Dirac electrons. Examples include graphite and bismuth both of which are known
for many years, together with graphene, a single layer of graphite, recently
addressed intensively after its realization. Another recent example is a
molecular solid, alpha-ET2I3, which is described by an equation similar to Weyl
equation with massless Dirac cones but the coordinate axis is tilted because of
the location of cones at off-symmetry points. Orbital susceptibility of such
Dirac electrons in graphite and bismuth has been known to have striking
features not present in ordinary band electrons but resulting from the
inter-band matrix elements of magnetic field. Results of theoretical studies on
not only orbital susceptibility but also Hall effect of such Dirac electrons in
molecular solids with tilting are introduced in this paper.Comment: 6 pages, 3 figure
Histological characteristics of incidentally-found growing meningiomas
Object. With the wider use of CT and MRI, many meningiomas are discovered as incidental findings during diagnostic work-up for unrelated symptoms. The majority shows no or minimal growth. The purpose of this study was to distinguish pathological features of incidentally-found growing meningiomas by comparing incidentally-found with symptomatic meningiomas. Methods. One hundred and thirty two consecutive nonrecurrent surgically-treated meningiomas treated between 2005 and 2007 were divided into three categories : 19 incidentally-found growing meningiomas (IG), 50 incidentallyfound meningiomas (I), and 63 symptomatic (S) meningiomas. The average follow-up period for the IG meningiomas was 3.7 years. Six out of 19 patients of the IG meningiomas became symptomatic during observation. Results. There is a significant difference of the incidence of WHO grades I, II, and III between all three groups (p=0.035). The incidence of WHO grades II and III in groups IG, I, and S were 26%, 2%, and 10%, respectively. We compare MIB-1 staining index between three groups : an average was 3.8% in IG, 1.3% in I, and 2.4% in S meningiomas. Conclusions. Incidentally-found meningiomas need careful follow-up. One fourth of the meningiomas that showed signs of growing belonged to the atypical or malignant grade
Synthesis of Adaptive Robust Controllers for a Class of Nonlinear Systems with Input Saturations
This paper deals with a design problem of an adaptive robust controller for a class of nonlinear systems with specified input saturations. For the nonlinear system under consideration, the nonlinearity means unknown perturbations and satisfies the matching condition. In this paper, we show that sufficient conditions for the existence of the proposed adaptive robust controller giving consideration to input saturations are given in terms of linear matrix inequalities (LMIs). Finally, simple illustrative examples are shown
A Quantum Deformation of the Virasoro Algebra and the Macdonald Symmetric Functions
A quantum deformation of the Virasoro algebra is defined. The Kac
determinants at arbitrary levels are conjectured. We construct a bosonic
realization of the quantum deformed Virasoro algebra. Singular vectors are
expressed by the Macdonald symmetric functions. This is proved by constructing
screening currents acting on the bosonic Fock space.Comment: 15 pages, latex fil
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