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1.
We use Canvas Application Framework to analyze e-business models of Realestate.yahoo.com, Yahoo.com, Redfin.com, Realtor.com, Trulia.com, Zillow.com, and Craigslist.com. We investigate the similarities and differences among e-business models and how e-business model differentiation affects company success. We looked at which business model components, such as distribution channels, business partnerships, attracting customers, revenue streams, etc., are important. We further investigate whether the web-advertising, brokerage, virtual value-chain, or the diversified internet business model is used by each company, and which ones are more successful. We discover similarities and differences among e-business models. Differences include the use of revenue streams for generating revenue, the extent of partnerships, and the role they play in a company’s success. 相似文献
2.
Cherif M. Azzaz Luiz H. C. Mattoso Nicole R. Demarquette Ricardo J. Zednik 《应用聚合物科学杂志》2021,138(10):49959
Considerable effort has been devoted to improving the properties of PVDF (polyvinylidene fluoride), arguably the most technologically important piezoelectric polymer. Electrospinning has been found to be a particularly effective method of producing PVDF nanofibers with superior piezoelectric properties due to the resulting exceptionally high fraction of the piezoelectrically active crystalline β-phase. It is typically assumed that the high external electric fields applied during electrospinning enhance the formation of this β-phase, with the confused literature offering various unsatisfactory mechanistic explanations. However, by comparing PVDF nanofibers produced by two different processes (electrospinning and blowspinning), we show that the electric field is entirely unnecessary; indeed, the crystallization dynamics are principally driven by the applied mechanical stress, as evidenced by structurally identical 200 nm diameter PVDF fibers produced with and without external electric fields. 相似文献
3.
M. Hübner J.-E. Rocher S. Allaoui G. Hivet T. Gereke C. Cherif 《International Journal of Material Forming》2016,9(5):591-599
Composites based on 3D woven fabrics offer excellent mechanical properties due to the nearly non-crimp reinforcement fibers. Additionally, a reduced number of process steps results from the 3D nature of the reinforcement. Their in-plane and out-of-plane behaviors are purposefully adjustable to the expected loading conditions. A previously introduced modelling approach is extended to the simulation of 3D woven fabrics. The tensile, shear and bending behaviors of the fabric are considered in a material formulation for large deformations using shell elements. The model is successfully validated and parameter studies show the significant influence of shear and bending parameters on forming results. Furthermore, it is shown that also the forming process parameters have a significant influence on the draping results. It is concluded that the shearing and wrinkling can be reduced to a minimum with adapted material and process parameters. 相似文献
4.
The liquid phase of acetylation of 1,2-dimethoxybenzene with acetic anhydride has been investigated over a series of acid iron-mesoporous materials (Fe-MCM-41) synthesized by microwave irradiation method with different Si/Fe ratios (Si/Fe?=?80, 50, 10) and characterized by several spectroscopic techniques such as: N2 physical adsorption, ICP, XRD, TEM, FT-IR, and a temperature?Cprogrammed?Cdesorption (TPD) of pyridine. In fact, the catalyst Fe-MCM-41 (10) showed bigger performance in the acid-catalyzed acetylation of 1,2-dimethoxybenzene employing acetic anhydride as an acylating agent. Furthermore, the kinetics of the acetylation of 1,2-dimethoxybenzene over these catalysts have also been investigated. 相似文献
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Martin Kirsten Juliane Meinl Katrin Schönfeld Alexander Michaelis Chokri Cherif 《应用聚合物科学杂志》2016,133(29)
The performance of carbon fibers depends on the quality of the precursor and the conditions of the thermal treatment. In detail, for a PAN precursor fiber the viscosity of a spinning dope and the draw ratio during the spinning process needs to be considered. Through wet spinning, different types of PAN precursor fibers with defined spinning parameters, including solid content, solvent content in a bath, and especially draw ratio resulting in defined cross section diameters, were fabricated and analyzed with tensile tests, density investigations, SEM, TGA‐MS, FTIR, and XRD. The results show that the mechanical properties of the fibers correlate to crystallinity. The cross section diameter is strongly related to the morphology of the fibers after thermal treatment. By extending the postdrawing of PAN fibers high tenacities were obtained at the cost of the cross section shape. In addition, TGA measurements reveal trapped residues of the wet spinning process as well as show several chemical reactions takes place at the same time at different temperatures. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43698. 相似文献
7.
S. Gourdin L. Marcin M. Podgorski M. Cherif L. Carroz 《Journal of Materials Science》2017,52(24):13736-13747
Effective elastic properties and residual stresses were assessed in directionally solidified ternary eutectic ceramic, Al2O3/YAG/ZrO2, by finite element analyses. A 3D finite element model was generated from a CT scan, representative of the microstructure and with a similar volume fraction. Effective elastic properties were calculated by numerical homogenisation. They highlight a quasi-isotropic behaviour of the ternary eutectic ceramics. Despite the difficulties to measure the strain, the dispersion observed in the results and the limited reliability of the materials properties, the results constitute a step towards a better understanding of the material behaviour. Thermal residual stresses induced by the manufacturing were also evaluated. Tensile residual stresses in yttria-stabilised zirconia and compressive residual stresses in YAG and alumina were highlighted. This evaluation also shed light on the influence of the phase morphology in the microstructure. Indeed, the computed spatial distribution of the residual stresses showed that they are different from one position to another due to the variation in phase morphology and also to material properties variability. Therefore, it is important when numerically assessing the thermomechanical properties to take into account the microstructure morphology as well as the variability of material properties. 相似文献
8.
R. Böhm E. Hufnagl R. Kupfer T. Engler J. Hausding C. Cherif W. Hufenbach 《Applied Composite Materials》2013,20(6):1077-1096
A significant improvement in the properties of plastic components can be achieved by introducing flexible multiaxial textile grids as reinforcement. This reinforcing concept is based on the layerwise bonding of biaxially or multiaxially oriented, completely stretched filaments of high-performance fibers, e.g. glass or carbon, and thermoplastic components, using modified warp knitting techniques. Such pre-consolidated grid-like textiles are particularly suitable for use in injection moulding, since the grid geometry is very robust with respect to flow pressure and temperature on the one hand and possesses an adjustable spacing to enable a complete filling of the mould cavity on the other hand. The development of pre-consolidated textile grids and their further processing into composites form the basis for providing tailored parts with a large number of additional integrated functions like fibrous sensors or electroconductive fibres. Composites reinforced in that way allow new product groups for promising lightweight structures to be opened up in future. The article describes the manufacturing process of this new composite class and their variability regarding reinforcement and function integration. An experimentally based study of the mechanical properties is performed. For this purpose, quasi-static and highly dynamic tensile tests have been carried out as well as impact penetration experiments. The reinforcing potential of the multiaxial grids is demonstrated by means of evaluating drop tower experiments on automotive components. It has been shown that the load-adapted reinforcement enables a significant local or global improvement of the properties of plastic components depending on industrial requirements. 相似文献
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Tarek Hattab Cedric Jamet Cherif Sammari Soumaya Lahbib 《International journal of remote sensing》2013,34(20):7163-7177
Few studies have focused on the use of ocean colour remote sensors in the Gulf of Gabes (southeastern Tunisia). This work is the first study to evaluate the ocean colour chlorophyll-a product in this area. Chlorophyll-a concentrations were measured during oceanographic cruises performed off the Gulf of Gabes. These measurements were used to validate satellite data acquired from the Moderate Resolution Imaging Spectroradiometer (MODIS) on the Aqua satellite. First, two atmospheric correction procedures (standard and shortwave infrared) were tested to derive the remote-sensing reflectance, and then a comparison between two bio-optical (OC3M and MedOC3) algorithms were realized using the in situ measurements. Both atmospheric correction procedures gave similar results when applied to our study area indicating that most pixels were non-turbid. The comparison between bio-optical algorithms shows that using the regional bio-optical algorithm MedOC3 improves chlorophyll-a estimation in the Gulf of Gabes for the low values of this parameter. 相似文献