191 research outputs found
PIV measurement of internal flow in mini centrifugal pump
The diameter of the ventricular assist pump and cooling pump for electrical devices like servers is about a dozen millimetres and these kinds of pumps belong to the mini pump. The internal flow condition of the mini centrifugal pump has to be clarified because there are so many types of mini pumps according to special specifications and shapes. Therefore, in this research, an open impeller was adopted as a mini centrifugal pump with 55mm impeller diameter in consideration of reduction in impeller manufacturing cost and its internal flow was investigated. Since the outlet angle of the test impeller is large, the maximum efficiency flow rate moves to a large flow rate and the relatively high head and efficiency were obtained in large flow rate region. In the present paper, the velocity and vorticity distribution near the volute tongue are shown and the internal flow in the mini centrifugal pump is clarified based on the PIV measurement results
Precise charm to strange mass ratio and light quark masses from full lattice QCD
By using a single formalism to handle charm, strange and light valence quarks
in full lattice QCD for the first time, we are able to determine ratios of
quark masses to 1%. For we obtain 11.85(16), an order of magnitude
more precise than the current PDG average. Combined with 1% determinations of
the charm quark mass now possible this gives
92.4(1.5) MeV. The MILC result for yields = 3.40(7) MeV for the average of and quark masses.Comment: 4 pages, 2 figures. Version accepted by Physical Review Letters.
Changes include modifying the title, using the MILC value for m_s/m_l which
changes slightly the resulting up and down quark masses and their average,
adding some references and making other small adjustments to the text for
space reasons
A Prediction of the B*_c mass in full lattice QCD
By using the Highly Improved Staggered Quark formalism to handle charm,
strange and light valence quarks in full lattice QCD, and NRQCD to handle
bottom valence quarks we are able to determine accurately ratios of the B meson
vector-pseudoscalar mass splittings, in particular,
(m(B*_c)-m(B_c))/(m(B*_s)-m(B_s)). We find this ratio to be 1.15(15), showing
the `light' quark mass dependence of this splitting to be very small. Hence we
predict m(B_c*) = 6.330(7)(2)(6) GeV where the first two errors are from the
lattice calculation and the third from existing experiment. This is the most
accurate prediction of a gold-plated hadron mass from lattice QCD to date.Comment: 4 pages, 2 figure
Two dimensional SU(N) x SU(N) chiral models on the lattice
Lattice chiral models are analyzed by strong and weak
coupling expansions and by numerical simulations. order strong
coupling series for the free and internal energy are obtained for all . Three loop contributions to the internal energy and to the lattice
-function are evaluated for all and non-universal corrections to the
asymptotic parameter are computed in the ``temperature'' and the
``energy'' scheme. Numerical simulations confirm a faster approach to
asymptopia of the energy scheme. A phenomenological correlation between the
peak in the specific heat and the dip of the -function is observed.
Tests of scaling are performed for various physical quantities, finding
substantial scaling at . In particular, at three different
mass ratios are determined numerically and found in agreement, within
statistical errors of about 1\%, with the theoretical predictions from the
exact S-matrix theory.Comment: pre-print IFUP 29/93, revised version, 12 pages, 10 figures avaliable
on request by FAX or by mail. REVTE
One-Loop Matching of the Heavy-Light A_0 and V_0 Currents with NRQCD Heavy and Improved Naive Light Quarks
One-loop matching of heavy-light currents is carried out for a highly
improved lattice action, including the effects of dimension 4 O(1/M) and O(a)
operators. We use the NRQCD action for heavy quarks, the Asqtad improved naive
action for light quarks, and the Symanzik improved glue action. As part of the
matching procedure we also present results for the NRQCD self energy and for
massless Asqtad quark wavefunction renormalization with improved glue.Comment: 25 pages, 3 eps-figure
Spatial variability in iron nutritional status of large diatoms in the Sea of Okhotsk with special reference to the Amur River discharge
The Sea of Okhotsk is known as one of the most biologically productive
regions among the world's oceans, and its productivity is supported in part
by the discharge of iron (Fe)-rich water from the Amur River. However, little
is known about the effect of riverine-derived Fe input on the physiology of
the large diatoms which often flourish in surface waters of the productive
continental shelf region. We conducted diatom-specific immunochemical
ferredoxin (Fd) and flavodoxin (Fld) assays in order to investigate the
spatial variability of Fe nutritional status in the microplankton-sized
(20–200 μm; hereafter micro-sized) diatoms. The Fd index, defined
as the proportion of Fd to the sum of Fd plus Fld accumulations in the cells,
was used to assess their Fe nutritional status. Additionally, active
chlorophyll fluorescence measurements using pulse–amplitude-modulated (PAM)
fluorometry were carried out to obtain the maximum photochemical quantum
efficiency (<i>F</i><sub>v</sub>/<i>F</i><sub>m</sub>) of photosystem II for the
total micro-sized phytoplankton assemblages including diatoms. During our
observations in the summer of 2006, the micro-sized diatoms were relatively
abundant (> 10 μg C L<sup>−1</sup>) in the neritic region, and
formed a massive bloom in Sakhalin Bay near the mouth of the Amur River.
Values of the Fd index and <i>F</i><sub>v</sub>/<i>F</i><sub>m</sub> were high
(>0.9 and >0.65, respectively) near the river mouth, indicating that
Fe was sufficient for growth of the diatoms. However, in oceanic waters of
the Sea of Okhotsk, the diatom Fd index declined as cellular Fld accumulation
increased. These results suggest that there was a distinct gradient in Fe
nutritional status in the micro-sized diatoms from near the Amur River mouth
to open waters in the Sea of Okhotsk. A significant correlation between
dissolved Fe (D-Fe) concentration and the Fd index was found in waters off
Sakhalin Island, indicating that D-Fe was a key factor for the
photophysiology of this diatom size class. In the vicinity of the Kuril
Islands between the Sea of Okhotsk and the Pacific Ocean, micro-sized diatoms
only accumulated Fld (i.e., Fd index = 0), despite strong vertical mixing
consistent with elevated surface D-Fe levels (>0.4 nM). Since higher Fe
quotas are generally required for diatoms growing under low-light conditions,
the micro-sized diatoms off the Kuril Islands possibly encountered Fe and
light co-limitations. The differential expressions of Fd and Fld in
micro-sized diatoms helped us to understand how these organisms respond to Fe
availability in the Sea of Okhotsk in connection with the Amur River
discharge
One-Loop Self Energy and Renormalization of the Speed of Light for some Anisotropic Improved Quark Actions
One-loop corrections to the fermion rest mass M_1, wave function
renormalization Z_2 and speed of light renormalization C_0 are presented for
lattice actions that combine improved glue with clover or D234 quark actions
and keep the temporal and spatial lattice spacings, a_t and a_s, distinct. We
explore a range of values for the anisotropy parameter \chi = a_s/a_t and treat
both massive and massless fermions.Comment: 45 LaTeX pages with 4 postscript figure
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