457 research outputs found
Diversification-driven tabu search for unconstrained binary quadratic problems
This paper describes a Diversification-Driven Tabu Search (D²TS) algorithm for solving unconstrained binary quadratic problems. D²TS is distinguished by the introduction of a perturbation-based diversification strategy guided by long-term memory. The performance of the proposed algorithm is assessed on the largest instances from the ORLIB library (up to 2500 variables) as well as still larger instances from the literature (up to 7000 variables). The computational results show that D²TS is highly competitive in terms of both solution quality and computational efficiency relative to some of the best performing heuristics in the literature
The Financial Constraints and the Value of Cash Holdings: An Empirical Investigation of US Firms
Abstract
Financial constraint is an important problem when assessing the companies’ financial behaviours. This study investigates the cash flow sensitivity of cash, which is used for measuring the financial constraints; in addition, the impacts of cash holdings for both financially constrained and unconstrained firms are investigated; three proxies are used to classify the companies as constrained and unconstrained, which are dividend payout ratio, firm size and KZ index, respectively. By examining the US public firms during the period of 2005 to 2015, through utilizing the fixed effect model and GMM model, we conclude that the financially constrained firms hoard more cash reserves than the unconstrained firms; furthermore, the financially constrained firms have higher marginal value compared with the unconstrained firms, which means the firms face financial constraints will create more value with every extra dollar reserved
Effect of cooling rate on microstructure of B2-NiSc intermetallics
Ni-50at%Sc alloy was prepared by centrifugal
casting method. Volume fraction, the actual
content of B2-NiSc and second phase Ni2Sc in
alloy were analyzed with an Image-Pro Plus
software. The cooling rates for the solidified thin
plate with thickness of 2.65mm, 1.2mm, 0.75mm
and 0.35 mm are 1164, 2570, 4112 and 8811 K·s-
1, respectively. It is found that d=0.5 mm was an
critical dimension which corresponds to an abrupt
change in the solidification rate. It is also found
that (Ni2Sc+NiSc)eutectic was dispersed at grain
boundary or between dendritic arms due to the loss
of Sc element during melting. While d> 0.5mm
(corresponding to the thin plate with thickness of
0.75mm, 1.20mm and 2.65 mm), the solidification
structure consists of primary phase B2-NiSc and
(Ni2Sc+NiSc)eutectic. While d < 0.5mm
(corresponding to the thin plate with thickness of
0.35 mm), the solidification structure is composed
of fine globular B2-NiSc and relatively small
amounts of (Ni2Sc+NiSc)eutectic. Based on the phase
volumetric analyzing of the microstructure with an
Image-Pro Plus software, the loss of Sc element
during melting was about 3.01~3.10 at%. The
eutectic NiSc in the lamellar eutectic structure
together with the primary phase B2-NiSc form a
larger single phase NiSc, while Ni2Sc with the form
of particles is distributed on the grain boundaries
after (970 ℃, 72 h) homogenization heat
treatment
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