A DEM study of silo discharge of a cohesive solid

Bulk handling of powders and granular solids is common in many industries and often gives rise to handling difficulties especially when the material exhibits complex cohesive behaviour. For example, high storage stresses in a silo can lead to high cohesive strength of the stored solid, which may in turn cause blockages such as ratholing or arching near the outlet during discharge. This paper presents a Discrete Element Method study of discharge of a granular solid with varying levels of cohesion from a flat-bottomed silo. The DEM simulations were conducted using the commercial EDEM code with a recently developed DEM contact model for cohesive solids implemented through an API. The contact model is based on an elasto-plastic contact with adhesion and uses hysteretic non-linear loading and unloading paths to model the elastic-plastic contact deformation. The adhesion parameter is a function of the maximum contact overlap. The model has been shown to be able to predict the stress history dependent behaviour depicted by a flow function of the material. The effects of cohesion on the discharge rate and flow pattern in the silo are investigated. The predicted discharge rates are compared for the varying levels of cohesion and the effect of adhesion is evaluated. The ability of the contact model to qualitatively predict the phenomena that are present in the discharge of a silo has been shown with the salient feature of mixed flow from a flat bottomed hopper identified in the simulation.

An analytical solution for solid stresses in a silo with an inner tube

This paper presents an analytical solution for the solid stresses in a silo with an internal tube. The research was conducted to support the design of a group of full scale silos with large inner concrete tubes. The silos were blasted and formed out of solid rock underground for storing iron ore pellets. Each of these silos is 40m in diameter and has a 10m diameter concrete tube with five levels of openings constructed at the centre of each rock silo. A large scale model was constructed to investigate the stress regime for the stored pellets and to evaluate the solids flow pattern and the loading on the concrete tube. This paper focuses on the development of an analytical solution for stresses in the iron ore pellets in the silo and the effect of the central tube on the stress regimes. The solution is verified using finite element analysis before being applied to analyse stresses in the solid in the full scale silo and the effect of the size of the tube.

Undergraduate interprofessional education using high-fidelity paediatric simulation

BACKGROUND: High-fidelity simulation is becoming increasingly important in the delivery of teaching and learning to health care professionals within a safe environment. Its use in an interprofessional context and at undergraduate level has the potential to facilitate the learning of good communication and teamworking, in addition to clinical knowledge and skills.

METHODS: Interprofessional teaching and learning workshops using high-fidelity paediatric simulation were developed and delivered to undergraduate medical and nursing students at Queen's University Belfast. Learning outcomes common to both professions, and essential in the clinical management of sick children, included basic competencies, communication and teamworking skills. Quantitative and qualitative evaluation was undertaken using published questionnaires.

RESULTS: Quantitative results - the 32-item questionnaire was analysed for reliability using spss. Responses were positive for both groups of students across four domains - acquisition of knowledge and skills, communication and teamworking, professional identity and role awareness, and attitudes to shared learning. Qualitative results - thematic content analysis was used to analyse open-ended responses. Students from both groups commented that an interprofessional education (IPE) approach to paediatric simulation improved clinical and practice-based skills, and provided a safe learning environment. Students commented that there should be more interprofessional and simulation learning opportunities.

DISCUSSION: High-fidelity paediatric simulation, used in an interprofessional context, has the potential to meet the requirements of undergraduate medical and nursing curricula. Further research is needed into the long-term benefits for patient care, and its generalisability to other areas within health care teaching and learning.

Acute care teaching in the undergraduate nursing curriculum

AIM: To incorporate basic aspects of acute care into the undergraduate nursing programme by providing an opportunity for the development of knowledge and skills in the early recognition and assessment of deteriorating patients on general hospital wards.
BACKGROUND: Acute care initiatives implemented in the hospital setting to improve the identification and management of 'at risk' patients have focused on the provision of education for trained or qualified staff. However, to ensure student nurses are 'fit to practice' at the point of registration, it has been recommended that acute care theory and skills are incorporated into the undergraduate nursing curriculum.
PRACTICE DEVELOPMENT INITIATIVE: An 'Integrated Nursing Care' module was incorporated into year 3 of the undergraduate nursing programme to introduce students to acute care theory and practice. Module content focuses on the early detection and management of acute deterioration in patients with respiratory, cardiac, neurological or renal insufficiencies. We used a competency-based framework to ensure the application of theory to practice through the use of group seminars. High-fidelity patient-simulated clinical scenarios were a key feature. The United Kingdom Resuscitation Council Intermediate Life Support course is also an important component of the module.
CONCLUSIONS: Incorporating the Integrated Nursing Care module into the undergraduate nursing curriculum provides pre-registration students the opportunity to develop their knowledge and skills in acute care.
RELEVANCE TO CLINICAL PRACTICE: The provision of undergraduate education in care of the acutely ill patient in hospital is essential to improve nurses' competence and confidence in assessing and managing deteriorating patients in general wards at the point of registration.