排序方式: 共有107条查询结果,搜索用时 15 毫秒
101.
Artur Alho 《Physics letters. [Part B]》2011,703(5):537-542
We consider the evolution of covariant and gauge invariant linear density perturbations of scalar field cosmologies using a dynamical systems? approach. We find conditions for which the perturbations decay in time, so that the spacetime approaches a homogeneous solution which inflates, for quadratic and exponential potentials. This pre-inflationary homogenization is found to be stable in the potentials? parameter spaces. Furthermore, in each case, we determine the minimum size of the resultant homogeneous patch and show that, for quadratic potentials, the resulting inflationary solutions include those with the necessary number of e-folds. 相似文献
102.
An inventory control problem for deteriorating items with back-ordering and financial considerations
This paper investigates the effects of time value of money and inflation on the optimal ordering policy in an inventory control system. We proposed an economic order quantity model to manage a perishable item over the finite horizon planning under which back-ordering and delayed payment are assumed. The demand and deterioration rates are constant. The present value of total cost during the planning horizon in this inventory system is modeled first, then a three phases solution procedure is proposed to derive the optimal order and shortage quantities, and the number of replenishment during the planning horizon. Finally, the proposed model is illustrated through numerical examples and the sensitivity analysis is reported to find some managerial insights. 相似文献
103.
高明辉 《数学的实践与认识》2014,(20)
通过分析利用连续复利解释费雪效应公式中存在的问题,利用单位变化率概念给出了费雪效应关系新的表达式,并证明了所给公式与通常教材中的费雪效应公式等价. 相似文献
104.
105.
Here we investigate whether the deformation observed in an experiment in which the porcine circumflex coronary artery is subjected
to inflation at constant length included in the class,
,
,
. We find that this is not the case and discuss its implications in the study of the mechanics of this artery. Moreover, we
identify and quantify the uncertainty in the value of the invariants of the left Cauchy–Green tensor inferred from the 2D
motion of markers affixed to the surface of the test specimen, and suggest that 3D tracking of markers is needed due to inherent
bending and twisting induced by pressurization in vitro. 相似文献
106.
107.
We present a scalar triplet extension of the standard model to unify the origin of inflation with neutrino mass, asymmetric dark matter and leptogenesis. In presence of non-minimal couplings to gravity the scalar triplet, mixed with the standard model Higgs, plays the role of inflaton in the early Universe, while its decay to SM Higgs, lepton and dark matter simultaneously generate an asymmetry in the visible and dark matter sectors. On the other hand, in the low energy effective theory the induced vacuum expectation value of the triplet gives sub-eV Majorana masses to active neutrinos. We investigate the model parameter space leading to successful inflation as well as the observed dark matter to baryon abundance. Assuming the standard model like Higgs mass to be at 125–126 GeV, we found that the mass scale of the scalar triplet to be ?O(109) GeV and its trilinear coupling to doublet Higgs is ?0.09 so that it not only evades the possibility of having a metastable vacuum in the standard model, but also lead to a rich phenomenological consequences as stated above. Moreover, we found that the scalar triplet inflation strongly constrains the quartic couplings, while allowing for a wide range of Yukawa couplings which generate the CP asymmetries in the visible and dark matter sectors. 相似文献