Parametric cost analysis for web-based e-commerce of layer manufactured objects

Web-based e-commerce of rapid prototyping services is going to be a widely diffused methodology used to compete in a global market. A competitive market imposes a very accurate estimation of prototyping price. Prototype costs depend on many factors, some of which may be easily deduced, while some others consist in a complex function of the geometric model properties and of the specific technology employed to build a physical model. Build time, which affects some components of the prototype's build cost, is a critical factor to deduce. Build time depends not only on the prototype dimensions but also on the complexity of the shape that, in turn, affects the movement of the tool to form the object. A parametric approach to build cost estimation, suited for web-based e-commerce, is presented in this paper. Significant cost driving factors of layer manufactured objects are identified and instruments to evaluate them are proposed. Special attention has been paid to define a parametric approach to build time estimation. The proposed parametric approach analyses the geometrical features, which typically affect the build time of the main layer manufacturing technologies. The method is verified in some test cases related to FDM technology.     

当代法国风景园林行业中的女性

女性一直在风景园林行业发展中占有一席之地。欧洲以及法国的主要风景园林协会、联盟,都有女性积极参与,虽然并未官居要职,但数量上占有较大比例。对法国风景园林教育研究、设计实践的发展,女性都起到了重要的推动作用。对具有代表性的法国女风景园林师做了梳理与介绍,总结法国当代风景园林行业内女性的发展状况特征。未来,女性将在风景园林领域内持续发挥重要作用。     

Comparison of different uncertainty techniques in urban stormwater quantity and quality modelling

Urban drainage models are important tools used by both practitioners and scientists in the field of stormwater management. These models are often conceptual and usually require calibration using local datasets. The quantification of the uncertainty associated with the models is a must, although it is rarely practiced. The International Working Group on Data and Models, which works under the IWA/IAHR Joint Committee on Urban Drainage, has been working on the development of a framework for defining and assessing uncertainties in the field of urban drainage modelling. A part of that work is the assessment and comparison of different techniques generally used in the uncertainty assessment of the parameters of water models. This paper compares a number of these techniques: the Generalized Likelihood Uncertainty Estimation (GLUE), the Shuffled Complex Evolution Metropolis algorithm (SCEM-UA), an approach based on a multi-objective auto-calibration (a multialgorithm, genetically adaptive multi-objective method, AMALGAM) and a Bayesian approach based on a simplified Markov Chain Monte Carlo method (implemented in the software MICA). To allow a meaningful comparison among the different uncertainty techniques, common criteria have been set for the likelihood formulation, defining the number of simulations, and the measure of uncertainty bounds. Moreover, all the uncertainty techniques were implemented for the same case study, in which the same stormwater quantity and quality model was used alongside the same dataset. The comparison results for a well-posed rainfall/runoff model showed that the four methods provide similar probability distributions of model parameters, and model prediction intervals. For ill-posed water quality model the differences between the results were much wider; and the paper provides the specific advantages and disadvantages of each method. In relation to computational efficiency (i.e. number of iterations required to generate the probability distribution of parameters), it was found that SCEM-UA and AMALGAM produce results quicker than GLUE in terms of required number of simulations. However, GLUE requires the lowest modelling skills and is easy to implement. All non-Bayesian methods have problems with the way they accept behavioural parameter sets, e.g. GLUE, SCEM-UA and AMALGAM have subjective acceptance thresholds, while MICA has usually problem with its hypothesis on normality of residuals. It is concluded that modellers should select the method which is most suitable for the system they are modelling (e.g. complexity of the model’s structure including the number of parameters), their skill/knowledge level, the available information, and the purpose of their study.     

Correlations between jointing and seismic velocities in highly fractured rock masses

The paper presents the results of a study of heavily fractured calcareous rock masses outcropping in southern Italy based on both the unidimensional joint frequency (Nl) and rock quality designation (RQD) of rock cores and seismic velocity data from laboratory and down-hole tests. The in situ longitudinal wave velocities (v) were always very low and were correlated with both Nl and RQD. Between 1 and 2 km/s, small increases in velocity were associated with a considerable decrease in Nl and significant increase in RQD value. A velocity of 1.22 km/s corresponded to an RQD value of 0. The study indicated that the simple correlation proposed by the International Society for Rock Mechanics to evaluate the RQD from the unidimensional joint frequency can underestimate the results for heavily fractured rock masses, but that good correlations can be obtained between RQD and seismic velocity. Electronic Publication     

Molybdate doping of networks in epoxy–silica hybrids: Domain structuring and corrosion inhibition

Epoxy–silica hybrids were prepared from a silane-functionalized resin mixture of two diglycidyl ether bis-phenol A oligomers with different molecular weights, using molybdate anions as dopants for the siloxane domains.     

Modifications of proteoglycans secreted into the growth medium by young and senescent human skin fibroblasts

The properties of proteoglycans (PGs) secreted into the growth medium by normal young and senescent human skin fibroblasts (HFs) were investigated. In both cases, the incorporation per cell of radioactive precursors into total PGs was similar. The polysaccharide chains of PGs from young and senescent HFs were mainly represented by galactosaminoglycuronans and showed a similar range of size distribution. However, galactosaminoglycuronans of PGs secreted by senescent HFs had a lower content of unsulphated disaccharides and a lower proportion of D-glucuronosyl residues. Moreover, senescent HFs released into the growth medium higher relative amounts of small PGs with chondroitin sulphate, dermatan sulphate chains, such as decorin.