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61.
The elastic constantsC
11,C
12 andC
44 of sodium chlorate single crystal have been evaluated using 10 MHz ultrasonic pulse echo superposition technique. The values
areC
11=4.90,C
12=1.39,C
44=1.17 (× 1010
N/m
2) at 298 K and 6.15, 2.16, 1.32 (×1010
N/m
2) at 77 K. The data agree well with the values measured earlier up to 223 K. Brief mention is also made of the low temperature
bonding problems in these soft crystals. 相似文献
62.
The elastic constants of NaBrO3 and NaClO3 are evaluated from ultrasonic velocity measurements using pulse superposition techniques. The values of C11, C12 and C44 for NaBrO3 at 298°K are 5.578, 1.705, 1.510 (x 1010 N/m2) and for NaClO3 the values are 4.897, 1.389, 1.174. The values at 77°K are respectively 6.35, 1.98 and 1.65 for NaBrO3 and 6.15, 2.16 and 1.32 for NaClO3. 相似文献
63.
The electric field gradients at27Al and63Cu nuclei which are nearest neighbors to the muon in the face-centered cubic metals aluminum and copper, with muon at an octahedral
interstitial site, are studied. The electron density fluctuations needed for the evaluation of the electronic, or valence,
contributions to field gradients are taken from earlier investigations involving the spherical solid approximation. The enhancement
factors a that have to be applied to the electric field-gradients obtained from these approximations, due to the departures
of the electronic wave-functions from plane-wave character, and the incorporation of antishielding effects, have been obtained
for both APW and OPW approaches to the conduction electron wave-functions and good agreement is found between the results
by the two approaches. Size effects due to the lattice distortion associated with the presence of the muon are included through
actual point ion summations using available calculated displacements of the ions surrounding the muon. The valence contributions
are the dominant ones but the size effect contributions are also significant. The net field-gradient obtained for the27Al site is significantly smaller than experiment while that for63Cu is substantially larger than experiment. Possible sources that could lead to better agreement with experiment are discussed
and it is concluded that major improvement is needed in the valence effect contributions in both metals. 相似文献
64.
We extend the method of path integrals to obtain the solution of the chiral Schwinger model in curved space-time and compare it with the flat space-time solution. 相似文献
65.
The k‐th power of a graph G, denoted by , is a graph with the same set of vertices as G such that two vertices are adjacent in if and only if their distance in G is at most k. In this paper, we give the bounds on the spectral radius of and . The Nordhaus–Gaddum‐type inequality for the spectral radius of the graph is also presented. Moreover, we obtain an upper bound on the energy of the second power of graphs. 相似文献
66.
67.
68.
Kinkar Ch. Das 《Applied mathematics and computation》2011,217(18):7420-7426
We consider weighted graphs, where the edge weights are positive definite matrices. The eigenvalues of a graph are the eigenvalues of its adjacency matrix. We obtain a lower bound and an upper bound on the spectral radius of the adjacency matrix of weighted graphs and characterize graphs for which the bounds are attained. 相似文献
69.
The time-resolved multistage reservoir model well-known for semiconductor optical amplifier (SOA) is extended to analyze the behavior of a bulk homogeneous InP-InGaAsP buried heterostructure reflective semiconductor optical amplifier (RSOA). Parameters for simulation have been extracted from the experimental RSOA characteristics. We have employed the model to explain the steady-state and re-modulation dynamics in the RSOA. Electrical modulation bandwidth and intermodulation distortion in the RSOA have been derived from the model and close agreement is obtained with the reported data. It is found out that the ripples in the upstream output from the RSOA for incomplete modulation erase of downstream modulated data follow Gaussian distribution, which simplifies the calculation of upstream SNR and bit error rate. It is explained in detail that amplitude ripples in the upstream data can be reduced by judicious choice of optical and electrical parameters of the RSOA. In particular, for an average low downstream power level (<−20 dBm) a good downstream modulation erase factor about 89% and 23 dB extinction ratio in the upstream modulated signal can be achieved. 相似文献
70.
Rotational diffusion of two organic solutes, coumarin153 (C153) and 4-aminophthalimide (AP) has been investigated in four ionic liquids (ILs), viz. 1-ethyl-3-methylimidazolium trifluoroacetate (EMIMTFA), 1-ethyl-3-methylimidazolium ethylsulfate (EMIMESU), 1-ethyl-3-methylimidazolium tetrafluoroborate (EMIMTFB) and 1-ethyl-3-methylimidazolium tetracyanoborate (EMIMTCB), as a function of temperature. Between the two probes, AP can act as hydrogen-bond-donor to the solvents having hydrogen bond acceptor ability. The results indicate that the rotational dynamics of C153 is mainly governed by the viscosity of the medium. On the other hand, the rotational motion of AP is found to be significantly hindered in the ILs depending on the nature of anions of the ILs. Rotational coupling constant values for AP in the ILs follow the order TFA?>?ESU?>?TCB?>?TFB. The slower rotational motion of AP in these ILs has been attributed to the specific hydrogen bonding interaction between AP and anions of ILs. Figure
Rotational diffusion of two organic solutes, coumarin153 (C153) and 4-aminophthalimide (AP) has been investigated in four different ionic liquids (ILs) so as to monitor the effects of anions on the rotational dynamics of the solutes exclusively. Figure showing the anisotropy decay profile of AP at 293 K in two isoviscous room temperature ionic liquids having different hydrogen bond acceptors ability 相似文献