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991.
This paper explores whether the recognition of asset impairments provides an opportunity for earnings management by examining changes in the performance. First, we apply a dynamic data envelopment analysis model to evaluate the operating performance of Taiwanese electronics firms for the period from 2004 to 2013. Statistical tests are next applied to assess the average efficiency variation between the periods before and after firms recognise asset impairments. Several empirical findings are as follows: managers recognise asset impairments when their firms have poor performance as compared to other firms that do not record any asset impairments recognition, and that their performance keeps on improving in both the year of recognising asset impairments and the year after asset impairments recognition. That is, managers tend to recognise asset impairments to improve operating performance, while the firms are performing poorly, supporting the opportunistic behaviour theory. 相似文献
992.
Abstract The problem of trajectory sensitivity considered in the literature was restricted to the continuous‐time systems. Some of the criteria provided in previous work (9, 10) are extended to the discrete‐time control systems. Two methods based on the Z‐domain design technique are developed to overcome the difficulty of obtaining the variations of control due to the changes of system parameters. The obtained Z‐domain controllers are particularly suitable for implementation on a microprocessor or digital computer. 相似文献
993.
994.
Kun-Jung Hsieh Eugene Yee 《Journal of Wind Engineering & Industrial Aerodynamics》2007,95(12):1611-1636
A turbulent dispersion model describing the dispersion of a passive scalar from a localized source released in a built-up environment (urban area) is presented. The proposed model simulates both the flow field in the urban complex using the ensemble-averaged, three-dimensional Navier-Stokes equations with a standard k-ε turbulence closure model and the turbulent diffusion using transport equations for the mean concentration and concentration variance of the scalar. Two models for the scalar dissipation rate, required to close the transport equation for concentration variance, are investigated. Results of a detailed comparison of the flow and turbulent dispersion between a comprehensive water channel experiment and the model predictions are presented. The water channel experiment is unique in the sense that it includes data obtained from the dispersion of both continuous and nearly instantaneous releases of a tracer from a point source located within a regular array of building-like obstacles, and this data include measurements of both the mean concentration and concentration variance. 相似文献
995.
This paper treats energy and cost performance of a cooling source system with indirect seawater utilization for air conditioning in a commercial complex. Seawater utilization has merits as a cooling source, because seawater temperature is lower than outdoor air in summer and it is cost effective because there is no water monetary cost. Actual operating data has been measured for about 2 years and the chiller and system co-efficient of performance (COP) have indicated about 4.77 and 2.93, respectively, even in summer season and the mean efficiency of the thermal storage system was about 89.9% taking into account heat loss of pumps. In addition, we have constructed simulation models for cooling tower systems, air cooling chiller systems and direct seawater utilization systems then compared them to this system. The electric power consumption of the indirect seawater utilization system was almost the same as the other systems except the air cooling chiller system, because using lower seawater temperature made the chiller efficiency higher. In conclusion, our results showed the indirect seawater utilization system was able to improve the system COP compared to air cooling chiller system, and cancel water consumption compared with the cooling tower system, and cut down an initial and maintenance costs compared with the direct seawater utilization system. 相似文献
996.
Several hypotheses regarding the importance of gender and relationships were tested by combining a large survey dataset with unobtrusive behavioral data from 1 year of play. Consistent with expectations, males played for achievement‐oriented reasons and were more aggressive, especially within romantic relationships where both partners played. Female players in such relationships had higher general happiness than their male counterparts. Contrary to stereotypes and current hypotheses, it was the female players who played the most. Female players were also healthier than male players or females in the general population. The findings have implications for gender theory and communication‐oriented methods in games and online research—most notably for the use of self‐reported time spent, which was systematically incorrect and different by gender. 相似文献
997.
A dynamic regularized radial basis function network for nonlinear,nonstationary time series prediction 总被引:1,自引:0,他引:1
In this paper, constructive approximation theorems are given which show that under certain conditions, the standard Nadaraya-Watson (1964) regression estimate (NWRE) can be considered a specially regularized form of radial basis function networks (RBFNs). From this and another related result, we deduce that regularized RBFNs are m.s., consistent, like the NWRE for the one-step-ahead prediction of Markovian nonstationary, nonlinear autoregressive time series generated by an i.i.d. noise processes. Additionally, choosing the regularization parameter to be asymptotically optimal gives regularized RBFNs the advantage of asymptotically realizing minimum m.s. prediction error. Two update algorithms (one with augmented networks/infinite memory and the other with fixed-size networks/finite memory) are then proposed to deal with nonstationarity induced by time-varying regression functions. For the latter algorithm, tests on several phonetically balanced male and female speech samples show an average 2.2-dB improvement in the predicted signal/noise (error) ratio over corresponding adaptive linear predictors using the exponentially-weighted RLS algorithm. Further RLS filtering of the predictions from an ensemble of three such RBFNs combined with the usual autoregressive inputs increases the improvement to 4.2 dB, on average, over the linear predictors 相似文献
998.
The morphology, polymorphism behavior and molecular orientation of electrospun poly(vinylidene fluoride) (PVDF) fibers have been investigated. We found that electrospinning of PVDF from its N,N-dimethylformamide/acetone solutions led to the formation of β-phase. In contrast, only α- and γ-phase was detected in the spin-coated samples from the same solutions. In the aligned electrospun PVDF fibers obtained using a rotating disk collector, the β-phase crystallites had a preferred orientation along the fiber axis. The degree of orientation did not, however, vary significantly with the speed of the rotation disk collector, and the β-phase was also not significantly enhanced with the increase in the rotation speed or the decrease in the size of spinnerets. These facts indicated that the orientation was likely to be caused by Columbic force rather than the mechanical and shear forces exerted by the rotating disk collector and spinnerets. The Columbic force may induce local conformational change to straighter TTTT conformation, and hence promote the β-phase. The addition of 3 wt.% of tetrabutylammonium chloride (TBAC) into the polymer solutions effectively improved the morphology of the electrospun fibers, and led to almost pure β-phase in the fibers. With spin coating, PVDF-TBAC did not, however, show any strong β-phase diffraction peak. The synergistic β-enhancement effect of TBAC and electrospinning is possibly due to the fact that while TBAC could induce more trans conformers, electrospinning promotes parallel packing, and hence inter-chain registration. 相似文献
999.
This paper evaluates the performance of our recently proposed automatic machine translation evaluation metric MaxSim and examines the impact of translation fluency on the metric. MaxSim calculates a similarity score between a pair of English system-reference sentences by comparing information items such as n-grams across the sentence pair. Unlike most metrics which perform binary matching, MaxSim also computes similarity scores between items and models them as nodes in a bipartite graph to select a maximum weight matching. Our experiments show that MaxSim is competitive with state-of-the-art metrics on benchmark datasets. 相似文献
1000.