55,013 research outputs found
Proton modified Pt zeolite fuel cell electrocatalysts
NaY Zeolite is selected as a suitable material to host 1.5 wt% Platinum (Pt) loading on zeolite using ion exchange method (a) Pt(NH3)4(NO3)2 without excess NH4NO3 nitrate and (b) Pt(NH3)4(NO3)2 with excess NH4NO3 nitrate. The structure/reactivity relationship of Pt nanoparticle has been experimentally studied via Nafion@ bound electrodes to investigate the interaction nature of Pt with zeolite and electron transfer using the extended X-ray adsorption fine structure (EXAFS) and Pt particle was predicted at 0.7 – 1.5 (nm). Pt oxides can be electrochemically reduced via a hydrogen ‘spillover’ phenomenon. A highly dispersed small Pt particle distribution can be achieved with excessive H+ ions on zeolite acidic sites
Systematic study of the symmetry energy coefficient in finite nuclei
The symmetry energy coefficients in finite nuclei have been studied
systematically with a covariant density functional theory (DFT) and compared
with the values calculated using several available mass tables. Due to the
contamination of shell effect, the nuclear symmetry energy coefficients
extracted from the binding energies have large fluctuations around the nuclei
with double magic numbers. The size of this contamination is shown to be
smaller for the nuclei with larger isospin value. After subtracting the shell
effect with the Strutinsky method, the obtained nuclear symmetry energy
coefficients with different isospin values are shown to decrease smoothly with
the mass number and are subsequently fitted to the relation . The resultant volume and
surface coefficients from axially deformed covariant DFT calculations are
and MeV respectively. The ratio is in good
agreement with the value derived from the previous calculations with the
non-relativistic Skyrme energy functionals. The coefficients and
corresponding to several available mass tables are also extracted. It is shown
that there is a strong linear correlation between the volume and surface
coefficients and the ratios are in between for all
the cases.Comment: 16 pages, 6 figure
Cross-Correlation-Function-Based Multipath Mitigation Method for Sine-BOC Signals
Global Navigation Satellite Systems (GNSS) positioning accuracy indoor and urban canyons environments are greatly affected by multipath due to distortions in its autocorrelation function. In this paper, a cross-correlation function between the received sine phased Binary Offset Carrier (sine-BOC) modulation signal and the local signal is studied firstly, and a new multipath mitigation method based on cross-correlation function for sine-BOC signal is proposed. This method is implemented to create a cross-correlation function by designing the modulated symbols of the local signal. The theoretical analysis and simulation results indicate that the proposed method exhibits better multipath mitigation performance compared with the traditional Double Delta Correlator (DDC) techniques, especially the medium/long delay multipath signals, and it is also convenient and flexible to implement by using only one correlator, which is the case of low-cost mass-market receivers
Monotone Linear Relations: Maximality and Fitzpatrick Functions
We analyze and characterize maximal monotonicity of linear relations
(set-valued operators with linear graphs). An important tool in our study are
Fitzpatrick functions. The results obtained partially extend work on linear and
at most single-valued operators by Phelps and Simons and by Bauschke, Borwein
and Wang. Furthermore, a description of skew linear relations in terms of the
Fitzpatrick family is obtained. We also answer one of Simons problems by
showing that if a maximal monotone operator has a convex graph, then this graph
must actually be affine
Rectangularity and paramonotonicity of maximally monotone operators
Maximally monotone operators play a key role in modern optimization and
variational analysis. Two useful subclasses are rectangular (also known as star
monotone) and paramonotone operators, which were introduced by Brezis and
Haraux, and by Censor, Iusem and Zenios, respectively. The former class has
useful range properties while the latter class is of importance for interior
point methods and duality theory. Both notions are automatic for
subdifferential operators and known to coincide for certain matrices; however,
more precise relationships between rectangularity and paramonotonicity were not
known.
Our aim is to provide new results and examples concerning these notions. It
is shown that rectangularity and paramonotonicity are actually independent.
Moreover, for linear relations, rectangularity implies paramonotonicity but the
converse implication requires additional assumptions. We also consider
continuous linear monotone operators, and we point out that in Hilbert space
both notions are automatic for certain displacement mappings
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