Wheat bran-based biorefinery 2: Valorization of products

Wheat bran is multi-layered and consists of different cell types with different chemical compositions. The relatively high content of protein as well as the small amount of lignin is the key differentiator to other lignocellulose containing biomasses. Following the classical route of a biorefinery, bran may be disintegrated to a high extent and separated into fractions of high purity in order to build up new chemicals which serve as precursors for higher polymerized compounds. Secondly, bran contains substances that are per se valuables, but need to be further separated and purified.     

Mesh objective continuum damage models for ductile fracture

During machining processes, the work piece material is subjected to high deformation rates, increased temperature, large plastic deformations, damage evolution and fracture. In this context the Johnson‐Cook failure model is often used even though it exhibits pathological mesh size dependence. To remove the mesh size sensitivity, a set of mesh objective damage models is proposed based on a local continuum damage formulation combined with the concept of a scalar damage phase field. The first model represents a mesh objective augmentation of the well‐established element removal model, whereas the second one degrades the continuum stress in a smooth fashion. Plane strain plate and hat specimens are used in the finite element simulations, with the restriction to the temperature and rate independent cases. To investigate the influence of mesh distortion, a structured and an unstructured meshes were used for the respective specimen. For structured meshes, the results clearly show that the pathological mesh size sensitivity is removed for both models. When considering unstructured meshes, the mesh size sensitivity is more complex as revealed by the considered hat‐specimen shear test. Nevertheless, the present work indicates that the proposed models can predict realistic ductile failure behaviors in a mesh objective fashion. Copyright © 2015 John Wiley & Sons, Ltd.     

Restricted energy loss of ultrarelativistic particles in thin targets - A search for deviations from constancy

Experimental results for the restricted energy loss of ultrarelativistic electrons, with Lorentz factors up to 3×10⁵, in a thin silicon detector are presented. The combination of high Lorentz factors and thin targets, opens for the possibility to study two mutually excluding effects, both based upon theory and on scarce experimental observations. One is a disappearance of the density effect when the transit time becomes so short that the effect of plasma-oscillations becomes negligible. This would result in an increased energy loss as the Lorentz factor increases. The other is an effect based on the existence of a coherence length over which there are contributions to the energy loss. This effect leads to a substantially decreased energy loss for thin targets as the Lorentz factor increases. The latter is shown to be incompatible with our measurements, whereas the former may be present with a correction of a few percent to an otherwise constant energy loss. Furthermore, we point to significant effects related to synchrotron and transition radiation, that must be carefully considered in a possible future experiment, and may as well have been of significance for the conclusion in earlier experiments.     

Polymer-derived ceramic molten metal filters

Journal of Materials Science - This paper reports the synthesis and the performance of polymer-derived ceramic filters for molten metal filtration. Two different filter types were studied: foam...     

Comparative study of European tunnel emergency-stop-area-wall protection measures

Due to the increasing number of traffic accidents involving the collisions of vehicles with the emergency-stop-area head walls in tunnels, a comparative numerical analysis in accordance with the EN 1317 standard has been performed in order to assess the quality of the available protective safety barriers. Based on the simulation results, the values of the relevant injury criteria – the acceleration severity index (ASI), the theoretical head impact velocity (THIV) and the post-impact head deceleration (PHD) – were computed for several collision scenarios involving two different passenger vehicles colliding with two different safety barriers in various ways. The results show that due to the geometrical restrictions in the tunnel's emergency stop area none of the barriers can provide total protection for the occupants of the vehicle in the event of a collision. The installation of a steel-sheet-tube crash cushion was, however, found to provide the best possible protection within the given limitations. The results of the analysis were the basis for selecting a safety-barrier design for existing tunnel installations and for the proposed changes in regulations governing the geometry of the tunnel's emergency stop area.     

Influence of wire mesh characteristics on reinforced soil model wall failure mechanisms-physical and numerical modelling

This paper presents the details of experimental and numerical analysis performed on three 0.8?m-high reinforced earth model walls with strip footing surcharge near the wall facing. The study investigates how wire mesh strength and geometry affect the failure mechanism. All three walls were nominally identical, except for reinforcement strength and geometry. The displacement field of the entire cross section was captured by high-resolution digital camera through transparent sidewall. The resulting images were analyzed using digital image correlation software. The results indicate that both reinforcement strength and aperture size influence the type of failure mechanism. Numerical modelling was also applied to assess the influence of sidewall friction (3D model) and reinforcement stiffness and strength (2D model) on the failure mechanism of the walls. The parameters for the numerical models were derived from independent tests and results, which were compared with the experimental observations. A good level of agreement with measurements was confirmed, even for the 2D model that excluded sidewall friction.     

Friction and wear characterization of sintered low alloyed chromium steels for structural components

Sintered and sintered/gas nitrided cylinders made of low alloyed chromium steel Astaloy CrL + 0.45 C at 7.25 g/cm³ density, have been tested for scuffing resistance and wear rate in a crossed cylinders test setup lubricated with a commercial SAE 10W40 engine oil at 90 °C. The results show large potential of 1 h gas nitriding of the sintered chromium steel cylinders. The nitrided cylinders experienced safe wear at 1000 MPa and scuffing at 1100 MPa at 2.5 m/s. At 0.5 and 0.1 m/s at least up to 800 MPa the wear was mild, as sintered chromium cylinders showed scuffing at pressure lower than 320 MPa and limited wear at 0.5 and 0.1 m/s.