268 research outputs found
Exergetic performance and comparative assessment of bottoming power cycles operating with carbon dioxideâbased binary mixture as working fluid
This paper presents CO2-toluene (CO2-C7H8) binary mixture as working fluid to enhance the energetic and exergetic performance of CO2 bottoming power cycles in warm ambient conditions. A criterion for selection of CO2-based binary mixture is defined, and 0.9 CO2/0.1 C7H8 composition is decided based on the required minimum cycle temperature compatible with ambient conditions. Bottoming simple regenerative cycle (BSRC) and bottoming preheating cycle (BPHC) configurations are selected, and their realistic operating conditions are determined based on sensitivity analysis. The performance of bottoming cycles using CO2-C7H8 binary mixture is compared with the bottoming cycles using pure CO2 as working fluid at different ambient temperatures. It is observed that the cycles operating with pure CO2 can only perform better at lower ambient temperature conditions, whereas, at the increased ambient temperatures, bottoming cycles with CO2-C7H8 binary mixture outperform and produce significant gains in exergetic and energetic performance compared with pure CO2 bottoming cycles. A maximum gain of exergetic efficiency for BSRC and BPHC observed is 26.83% and 18.71%, respectively, at an operating ambient temperature of 313 K, whereas an overall gain in energetic efficiencies for BSRC and BPHC observed is 28.92% and 10.12%, respectively. Taking into consideration thermodynamic performance, overall UA (product of overall heat transfer coefficient and heat transfer area for the heat exchanger) and specific investment cost, BPHC configuration is suggested as reasonable choice for higher ambient temperature conditions
Hadronic Mass Moments in Inclusive Semileptonic B Meson Decays
We have measured the first and second moments of the hadronic mass-squared
distribution in B -> X_c l nu, for P(lepton) > 1.5 GeV/c. We find <M_X^2 -
M_D[Bar]^2> = 0.251 +- 0.066 GeV^2, )^2 > = 0.576 +- 0.170
GeV^4, where M_D[Bar] is the spin-averaged D meson mass.
From that first moment and the first moment of the photon energy spectrum in
b -> s gamma, we find the HQET parameter lambda_1 (MS[Bar], to order 1/M^3 and
beta_0 alpha_s^2) to be -0.24 +- 0.11 GeV^2. Using these first moments and the
B semileptonic width, and assuming parton-hadron duality, we obtain |V_cb| =
0.0404 +- 0.0013.Comment: 11 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLNS, submitted to PR
Observation of the Charmed Baryon at CLEO
The CLEO experiment at the CESR collider has used 13.7 fb of data to
search for the production of the (css-ground state) in
collisions at {\rm GeV}. The modes used to
study the are ,
, , , and
. We observe a signal of 40.49.0(stat) events
at a mass of 2694.62.6(stat)1.9(syst) {\rm MeV/}, for all modes
combined.Comment: 10 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
Observation of and
We have studied two-body charmless hadronic decays of mesons into the
final states phi K and phi K^*. Using 9.7 million pairs collected
with the CLEO II detector, we observe the decays B- -> phi K- and B0 -> phi K*0
with the following branching fractions: BR(B- -> phi K-)=(5.5 +2.1-1.8 +- 0.6)
x 10^{-6} and BR(B0 -> phi K*0)=(11.5 +4.5-3.7 +1.8-1.7) x 10^{-6}. We also see
evidence for the decays B0 -> phi K0 and B- -> phi K*-. However, since the
statistical significance is not overwhelming for these modes we determine upper
limits of <12.3 x 10^{-6} and <22.5 x 10^{-6} (90% C.L.) respectively.Comment: 9 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
Evidence of New States Decaying into
Using 13.7 of data recorded by the CLEO detector at CESR, we report
evidence for two new charmed baryons: one decaying into
with the subsequent decay , and its
isospin partner decaying into followed by
. We measure the following mass differences
for the two states: =318.2+-1.3+-2.9 MeV,
and =324.0+-1.3+-3.0 MeV. We interpret
these new states as the particles, the charmed-strange
analogs of the .Comment: 10 pages postscript, also available through
http://w4.lns.cornell.edu/public/CLN
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