Analysis of the flowability of cohesive powders using Distinct Element Method

Computer simulations using Distinct Element Method (DEM) have been carried out to investigate the effect of cohesion on the flowability of polydisperse particulate systems. For this purpose, two assemblies with different values of surface energy and made of 3000 spheres with the mechanical properties of glass beads were considered. The analysis of the flowability of the powders is presented in terms of the unconfined yield stress as a function of strain rate for different pre-consolidation loads. For values of the surface energy of 1.0 J/m2 and strain rates lower than 6 s− 1, the unconfined yield stress does not change significantly indicating a quasi-static behaviour of the particulate assemblies during the compression process. For larger strain rates, the unconfined yield stress varies with the power index of 1.2 of the strain rate. The influence of the pre-consolidating stress on the powder behaviour has also been investigated and a flow factor was obtained from the linear relationship between the unconfined yield stress and pre-consolidation stress. The computer simulations show qualitatively a good agreement with the experimental trends on highly cohesive powder flow behaviour

Analysis of the effect of cohesion and gravity on the bulk behaviour of powders using Discrete Element Method

Computer simulations using Distinct Element Method have been carried out to analyse the bulk behaviour of a polydisperse assembly of glass beads. For this purpose an assembly made of 3000 spheres were generated to which the mechanical properties of glass beads were assigned. The system was initially compressed isotropically at a strain rate of 1 s-1 in the absence of gravity and surface energy. Once the assembly reached a packing fraction of about 0.62, the effects of cohesion and gravity on the bulk behaviour were analysed for two different cases. In the first case only gravity was applied, whilst in the second case both gravity and surface energy were acting on the particles. The evolution of the components of the stress tensor for the case in which only gravity was applied indicated that the gravity did not appreciably affect the isotropy of the system. In contrast, the system in which surface energy was introduced became anisotropic. The concept of unconfined yield stress of bulk cohesive powders was used to analyse the effect of surface energy and strain rate. For values of surface energy of 1.0 J/m2 and of strain rate lower than 1 s-1 the unconfined yield strength did not change significantly indicating a quasi-static behaviour for the compression process. However, for values of strain rates larger than 1 s-1 the unconfined yield strength increased with the strain rate, following a power law trend with an index of 1.7

Simulation of the effect of bond strength on the breakage pattern of agglomerates by Distinct Element Method

Chemical, pharmaceutical and food industries amongst many others use agglomerates either as intermediate or manufactured products. The mechanical strength of agglomerates under impact or shear deformation during handling and processing is of great interest to these industries for optimising product specification and functionality. The effect of surface energy on agglomerate behaviour under impact has been investigated using Distinct Element Method (DEM). Four different agglomerates were formed and impacted against a target along the direction of gravity for three different values of the surface energy (0.35, 3.5 and 35.0 J/m²). The agglomerate breakage pattern was influenced by the surface energy and a transition in the mode of failure of agglomerates was observed when the surface energy was varied. Based on the previous work, the surface energy is expressed in terms of Weber Number, We=(V-V0²)ρD/γ. Agglomerates showed extensive deformation under impact at the lowest value of surface energy (0.35 J/m²) and no evidence of fragmentation was found for any value of impact velocity. In this case the agglomerates behaved macroscopically in a ductile mode. At values of surface energy larger than 3.5 J/m² the agglomerates fragmented at the same time as local damage around the impact site occurred. This type of behaviour is typical of semi-brittle material failure. Therefore, the breakage pattern of agglomerates is influenced by the surface energy

Receptores tirosina quinasa en cáncer

Máster Universitario en Biología y Clínica del Cáncer: Programa, Objetivos y Metodología.Peer Reviewe

Aguas azoadas, Valladolid : agua, duchas, pulverizaciones, inhalaciones

Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-201

I\u27ll Know It When I See It...I Think : United States v. Newman and Insider Trading Legislation

The Second Circuit\u27s decision in United States v. Newman has reinvigorated an important and longstanding debate about insider trading-whether insider trading should be explicitly prohibited by statute. In response to the Second Circuit\u27s decision, Congress introduced three bills to codify insider trading liability. Each bill takes a different approach to codifying insider trading liability. Between the three bills, two general approaches emerged. One approach is to impose a broad prohibition on insider trading that arguably leaves the existing insider trading regime untouched. The second approach develops a narrower, carefully delineated standard of liability that departs from the current insider trading regime in important ways. Both approaches deserve careful scrutiny if Congress decides to move forward with codifying insider trading liability by statute. First, to provide a foundation, this Comment briefly traces the judicial development of insider trading liability through the U.S. Supreme Court\u27s previous decisions on insider trading. Next, this Comment discusses United States v. Newman and the executive and judicial responses to that decision. This Comment then discusses the need for codifying insider trading liability by statute and the potential benefits of codification. Next, a careful analysis of each bill identifies its strengths and weaknesses. Even small differences between bills impose vastly different standards of liability and provide varying levels of guidance for market actors, prosecutors, and the courts. Finally, this Comment proposes changes to the bills\u27 established frameworks and outlines other considerations Congress should consider if it decides to codify insider trading liability by statute

Five signs you might be in a corporate cult

Organisational culture plays a role in firm performance and can help improve employee satisfaction, engagement and commitment. But sometimes corporations can behave more like a cult, a phenomenon that can lead to employee exploitation and harmful or unethical behaviour. Teresa Almeida lists five signs to help you tell the difference between an organisation with a strong culture and one that is a bit too “cultish”

Language diversity in the workplace can spur creativity and innovation

Our first language shapes how we think. Each one of us carries unique knowledge and different ways of dealing with complex problems. Bringing together people from diverse language backgrounds can spur creativity and innovation in the workplace. Teresa Almeida presents four actions to create a more inclusive work environment for people of all mother tongues