虚拟群体与动态视频场景的在线实时融合

将虚拟人群与实拍视频场景融合实现虚拟人群对现实场景中动态目标的合理避让,是增强现实技术有待解决的一个新问题.文中首先对实拍视频流进行分析,获取真实动态目标在三维空间中的运动信息;然后将动态目标的运动转化为每个虚拟角色的约束条件,实时更新虚拟角色的运动决策,实现其对现实场景中动态目标的避让以及虚拟角色之间的避让.为了清晰地展示现实世界中多个目标的空间位置关系,还对视频画面中的目标体做了精确的实时分割,以产生正确的遮挡关系和目标定位.最后通过实验结果表明了该算法的有效性.     

Case Study: Retrofitting Large Bridge Piers on the Nakdong River, South Korea

The Gupo Bridge crosses the Nakdong River near the city of Busan, South Korea. During Typhoon Maemi in 2003, the old Gupo Bridge collapsed due to excessive pier scour. More recently, the highway construction on the left-bank floodplain required right-bank channel widening to restore the channel flood-carrying capacity. This 7?m deep floodplain excavation is expected to cause significant local scour around the 8–10?m wide and 3?m thick spread footings of Piers 11 and 12 of the Subway Bridge and Piers 15 and 16 of the Gupo Bridge. Three design options are examined for retrofitting floodplain bridge piers with massive spread footings. A solution with sheet piles and riprap was recommended in 2006 as the most appropriate design, but Plan III with a conical riprap structure around the footings was ultimately constructed in 2007 for economic reasons. Laboratory experiments also highlight the need to place gravel and synthetic filters under the designed riprap.     

Real-space tight-binding approach to electronic structure and stability in substitutional alloys

A real-space approach based on the tight-binding approximation is proposed for studying electronic structure properties, stability and order in substitutional multi-component chemically random alloy based on periodic as well as topological disordered lattices. We show that the coherent potential approximation (CPA) equations including Shiba's off-diagonal disorder can be solved self-consistently in real-space with the same accuracy currently achieved in reciprocal space. An effective one-electron Green function is given by a continued fraction expansion, and the associated effective medium is used to determine the effective cluster interactions which enter the expression of the configurationl part of the total energy for describing order-disorder phenomena in alloys. Some applications will be presented.     

Phase correlation between longitudinal modes in semiconductor self-pulsating DBR lasers

Phase correlation leading to self-pulsation (SP) in semiconductor distributed Bragg reflector (DBR) lasers is investigated experimentally and theoretically. Under proper biasing conditions, the laser oscillates with three main modes and we observe that each two-modes beating provides SP with identical spectral linewidth. Under the same operating conditions, the measured spectral linewidths of the beating modes are much larger than the linewidth of the self-pulsating signal. These results demonstrate the natural occurrence of passive mode-locking (PML) and phase correlation in semiconductor DBR lasers. A model based on multimode coupled-wave rate equations, including four-wave mixing (FWM), is developed to describe PML and SP in the gain region of the laser cavity. This model demonstrates that the existence of phase correlation between longitudinal modes is due to FWM.     

The in Vitro Pfnetration of Hydrophilic and Lipophilic Drugs from Transparent Oil-Water Gels Through Excised Human Epidermis: A Comparative Study with Other Dermatological Vehicles

Within the scope OF evaluating transparent oil-water gels as dermatological vehicles, the percutaneous absorption of both a hydrophilic drug, tetracaine hydrochloride, and a lipophilic drug, benzyl nicotinate, is studied using excised human epidermis. From a comparison of the results with those of release experiments, it appears that in most cases the penetration of both drugs through the epidermis occurs at a much lower rate than their release from the vehicles. This indicates that the penetration process constitutes the rate limiting step.

For both drugs the penetration rate from the transparent oil-water gel through human epidermis is comparable to those from other commonly used vehicles. Due to the higher lipophilicity of benzyl nicotinate, however, its penetration occurs faster than for tetracaine hydrochloride. As to the influence OF drug concentration in the vehicle on penetration rate, the results do not provide a decisive answer.     

Influence of moisture content on the specific methanogenic activity of dry mesophilic municipal solid waste digestate

The objective of this study was to evaluate the influence of moisture content on the specific methanogenic activity (SMA) of a fresh dry mesophilic digestate from a municipal solid waste digester plant. For this purpose, SMA tests were performed under mesophilic conditions in 500 mL glass bottles of volume used as batch reactors, during a period of 20–25 days. Cellulose, propionate and acetate were used as substrates (5 g_COD kg^?1 digestate) at four different moisture contents, ranging from 65 to 82%. The moisture content strongly influenced the specific methanogenic activity. The highest SMA values were observed at a moisture content of 82% (11.1, 7.8 and 6.0 mg_COD g_VS^?1 d^?1 for cellulose, propionate and acetate spikes, respectively). SMA and moisture content were found to be linearly linked. Dry digestion at low water content is thus detrimental to the biological activity, probably due to physical limitations. Copyright © 2011 Society of Chemical Industry     

Nonparametric modeling of carbon prices

This paper constitutes the first exercise of nonparametric modeling applied to carbon markets. The framework of analysis is carefully detailed, and the empirical application unfolds in the case of BlueNext spot and ECX futures prices. The data is gathered in daily frequency from April 2005 to April 2010. First, we document the presence of strong nonlinearities in the conditional mean functions. Second, the conditional volatility functions reveal an asymmetric and heteroskedastic behavior which is dramatically different between carbon spot and futures logreturns. The results for spot prices are also robust to subsamples' decomposition. Third, we show in an out-of-sample forecasting exercise that nonparametric modeling allows reducing the prediction error by almost 15% compared to linear AR models. This latter result is confirmed by the Diebold–Mariano pairwise test statistic.     

Modelling elasticity of a hydrating cement paste

Concrete is a complex multi-scale composite involving multi-physics processes. As it is the only evolving component of concrete, the cement paste has a major influence on the mechanical properties of concrete at early age. This paper focuses on the increase of the elastic properties of a cement paste during its hydration. The homogenization theory for disordered media is used in order to estimate the evolution of the effective elastic moduli of the hydrating paste. The morphological model refers to two types of C-S-H (calcium silicate hydrates, main hydration products of Portland cements) distinguished by many authors: inner products or high density C-S-H build up layers surrounding the anhydrous particles, while the outer products or low density C-S-H play the role of a porous matrix.The simulations of the effective Young's modulus at late age during hydration and at the end of hydration prove to be in excellent agreement with the experimental results available in the literature.     

Modelling and estimating the reliability of stochastic dynamical systems with Markovian switching

In this paper, a general framework for the modelling of physical phenomena with stochastic dynamical systems switched by jump Markov processes is given. A methodology of the associated estimation procedures is provided. A particular attention is paid to the estimation of the underlying jump process, which is not observable.As an application, a stochastic model is proposed for the fatigue crack growth problem. The estimation of the model parameters is made on a real crack growth data set. We are thus able to simulate some crack growth paths which are used for reliability analysis through Monte Carlo techniques.