Discrete element modelling of the dynamic behaviour of non-spherical particulate materials

PhD ThesisA numerical model based on the discrete element (DE) method, for modelling the flow of irregularly shaped, smooth-surfaced particles in a 3-D system is presented. An existing DE program for modelling the contact between spherical particles in periodic space (without real walls or boundaries) was modified to model non-spherical particles in a system with containing walls. The new model was validated against analytical calculations of single particle movements and also experimentally against data from physical experiments using synthetic non-spherical particles at both a particle and bulk scale. It was then used to study the effect of particle shape on the flow behaviour of assemblies of particles with various aspect ratios discharging from a flat-bottomed hopper. The particles were modelled using the Multi-Sphere Method (MSM) which is based on the CSG (Constructive Solid Geometry) technique for construction of complex solids by combining primitive shapes. In this method particle geometry is approximated using overlapping spheres of arbitrary diameter which are fixed in position relative to each other. The contact mechanics and contact detection method are the same as those used for spheres, except that translation and rotation of element spheres are calculated with respect to the motion of the whole particle....Numerical simulations of packing and flow of particles from a flat-bottomed hopper with a range of aspect ratios were performed to investigate the effect of particle shape on packing and flow behaviour of a particulate assembly. It was found that the particle shape influenced both bed structure and flow characteristics such as flow pattern, shear band strength and the occurrence of bridging. The flow of the bed of spherical particles was smoother than the flow of beds of elongated particles in which flow was fluctuating and there was more resistance to shear.Ministry of Culture and Higher Education of IRAN: University of Mashhad

A review on medical plants affecting Staphylococcus aureus

Background and aims: Infectious diseases are among the most important causes of mortality around the world and according to the WHO report 10.5 million cases of death were happened due to infections. Staphylococcus aureus is one of the most important pathogen that its infections are varied from local infections to life threatening infections. With regard to high antibiotic resistance of this agent its control and treatment is a challenge in medicine. The aim of this study was to review the effective medicinal plants against S. aureus with special attention of native plants of Iran. Methods: A comprehensive literature review was performed on papers that have been published from 2004 till 2016 in data resources such as NCBI, Sciencedirect, Springer, Web of science and as well as local databases such as Irandoc, Islamic science citation (ISC) and magiran with special focus on those that have been reported native medicinal plants in Iran. The selected keywords were Staphylococcus aureus, medicinal plant, natural antibiotic, antibacterial plant and medicinal herbs. Results: Different studies were found that have reported effective medicinal plants against S. aureus and were able to significantly inhibit bacterial growth. As well as different parts of these plants have been investigated for antibacterial activity and found that considerable differences are present among these parts of plants. Conclusion: Based on the reported studies, there are different medicinal plants in Iran that can be regarded as effective source for discovery new antibacterial agents against S. aureus and treatment of resistant strains

Investigation of Operational Risk Management in the Insurance Industry

This article investigates the current practice of operational risk management in the insurance industry. Insurance companies face several risks that need to be managed but their key competencies and main contribution to society is to accept the risks assumed by companies and people, hence the strategic significance for people and governments that insurers protect their incomes and assets. Operational risk is nothing new in insurance industry, because of regulatory necessities; companies have initiated computation of risk capital for their operational losses. The important loss to the market values of both the insurers and the insurance industry caused by operational losses must provide an inducement for operational risk management in the insurance industry. Since operational risk management in the insurance industry is still in a stage of development a relatively new concept. The study can assist insurers with founding formal operational risk management processes and programs within their companies

The Impact of Risk Management on the Performance of Insurance Companies

Risk Management Like other fields of knowledge management and its application utilize specific knowledge, instructions, regulations and principles to achieve predefined predictions and objectives. Risk management has developed principles and procedures that individuals, enterprises (commercial and industrial), insurance companies and governments can use to perform the foresight task of assessing, controlling and financing losses based on the systematic risk management approach. To this end, it is always working to answer two fundamental questions about the likely future consequences of the risk management criteria, securing organizations and investments against risks and losses requires the formation of an intellectual and practical system that integrates risk-based policymaking. The study show  that insurance companies with great risk management have better return on equity and better performance in other key business factors in comparison with competitors who do not provide good importance to risk management

Adsorption properties and third sound propagation in superfluid 4^4He films on carbon nanotubes

We consider the adsorption properties of superfluid $^4$He films on carbon nanotubes. One major factor in the adsorption is the surface tension force arising from the very small diameter of the nanotubes. Calculations show that surface tension keeps the film thickness on the tubes very thin even when the helium vapor is increased to the saturated pressure. The weakened Van der Waals force due to the cylindrical geometry also contributes to this. Both of these effects act to lower the predicted velocity of third sound propagation along the tubes. It does not appear that superfluidity will be possible on single-walled nanotubes of diameter about one nm, since the film thickness is less than 3 atomic layers even at saturation. Superfluidity is possible on larger-diameter nanotube bundles and multi-walled nanotubes, however. We have observed third sound signals on nanotube bundles of average diameter 5 nm which are sprayed onto a Plexiglass surface, forming a network of tubes.Comment: 4 pages, accepted for Journal of Physics: Conference Series (Proceedings of LT25

Investigating the relationship between personality disorders and criminal thinking styles in prisoners convicted of violent crimes

Psychologists believe that there is a relationship between personality and criminal behavior. The aim of this study was to investigate the relationship between personality disorders and criminal thinking styles in prisoners convicted of violent crimes. To what extent is there a link between the types of personality disorder, the type of criminal thinking style, and the type of crime in prisoners convicted of violent crime? Is there a relationship between personality disorders in prisoners convicted of violent crimes and their gender? To what extent is there a relationship between the type of personality disorder of prisoners and the frequency of committing violent crimes? These are the factors that led to the research. The research method is a descriptive-correlational study, in which a sample of 996 offenders were selected in terms of demographic characteristics. Data were collected using a questionnaire in two sections: demographic information and Christian Texas Intellectual Thinking Questionnaires and Millon Personality Disorder. The results show that there is a relationship between the type of personality disorder and the type of crime in prisoners sentenced to violent crimes. Different styles of criminal thinking lead to certain forms of violent crime. It was observed that based on tables and inferential tests, different criminal thinking styles are related to the prevalence of different types of crime. It has been clearly observed that some disorders are more common among women offenders and others are more common among men. However, there are some disorders that are similar in men and women. Different styles of criminal thinking relate differently to the number of crimes, the history of the crime, and the history of the same crime, and this shows that different styles of criminal thinking can create different patterns in the commission of a crime

Organizational Learning and Organizational Resilience Knowledge Management as a Mediator in Public Organizations of Iran

The purpose of this article is the findings of the mediating effect knowledge management in the relationship between organizational learning and organizational resilience. The study adopts a cross-sectional design to collect data used to carry out mediation analysis. 28 public organizations in Iran were selected as the samples of this study. The survey was conducted among meddle and senior managers and respondents were asked to express the opinions related to the effects organizational learning as mediator in relationship between management and organizational resilience. Knowledge management had an effect on organizational resilience. Organizational learning did not have a direct effect on organizational resilience, except through the full mediation of Knowledge management. This suggests that without Knowledge management, public organizations of Iran may not improve their level of resilience. Utilizing a cross-sectional design with questionnaires is one of the limitations of this study. The results may be different in the private sector. A future research strategy that may overcome this limitation is one that involves longitudinal studies in which flow of study variables can be followed over time. In addition, using objective measures, archival data for some variables, may give results that are more objective. Keywords: Organizational learning, Knowledge management, Organizational resilience, Public section organization

The relationship between knowledge management and organizational learning within middle and senior managers of Iranian public organizations

The purpose of this study was to investigate the relationship between knowledge management and organizational learning. The sample for the study is consisted of 270 middle and senior managers from the 28 public organizations in Iran. The study utilized both quantitative data (questionnaire) and qualitative data (interview). Amah (2013) KM questionnaires and Watkins and Marsiek (2003) organizational learning were used. The reliability of the questionnaires in Iran renew determined. The pearson rank correlation coefficient and Multiple Regression Model using the Statistical Package for Social Sciences (SPSS) version 20 were utilized for the analysis of data. Our finding revealed a positive and significant relationship between knowledge management and organizational learning. Specifically, knowledge acquisition, knowledge storage, knowledge sharing and knowledge utilization were revealed to have a positive and significant influence on organizational learning. Based on this finding, it was concluded that knowledge management enhances organizational learning. It is recommended that organizations should continue to strengthen their knowledge management practices especially knowledge acquisition, knowledge storage, knowledge sharing and knowledge utilization in their everyday activities as this is a sure guarantee for their learning. Keywords: Knowledge Management, Organizational learning, Knowledge Acquisition, Knowledge Storage, Knowledge Sharing, Knowledge utilization

Knowledge Management and Organizational Resilience Organizational Learning as a Mediator in Iranian Public Organizations

The purpose of this study is to report the findings of the mediating effect of organizational learning in the relationship between knowledge management and organizational resilience. The study adopts a cross-sectional design to collect data used to carry out mediation analysis. As samples of the study 28 Iranian public organizations were selected. The survey was conducted among middle and senior managers and respondents were asked to express their opinions concerning roll of organizational learning as mediator in relationship between management and organizational resilience. Knowledge management and organizational learning as well are effective on increasing organizational resilience. However, in terms of mediating role of organizational learning findings were not similar to the result of previous studies. Organizational learning as mediator cannot have effective roll in increasing organizational resilience. Utilizing a cross-sectional design along with questionnaire is one of the limitations of the study. The results may be different in the private sector. A future research strategy that may overcome this limitation is one that involves longitudinal studies in which flow of study variables can be viewed over time. In addition, applying objective data, measures, archival data for some variables, may lead in more objective results. Keywords: Knowledge Management, Organizational Learning, Organizational Resilience, Public Section Organizations