Modelling, simulation, and analysis of supply chain systems using discrete-event simulation.

Many approaches have been developed which support the construction of detailed supply chain models useful for analysis and simulation. However, most of these approaches lack the ability to model the supply chain in a single model, and usually produce solutions that lead to conflicting strategies between the companies. Simulation using a discrete-event simulation (DES) is an effective tool for the dynamically changing supply chain variables, thus allowing the system to be modelled more realistically. Considering the complexities of the supply chain system and the interrelations between its various systems, the task of developing such a model is challenging. The aim of this thesis is to develop a simulation model of a fast moving consumer goods (FMCG) supply chain with a DES tool. This model would be utilised as a decision-support system (DSS) for the investigation of the effectiveness of several inventory policies towards effective coordination and control of production inventory system, in various situations. This thesis discusses fundamental issues in the development of a simulation model for a supply chain using the DES tool, ARENA. A modelling procedure for the development of a supply chain simulation model is presented. The overall structure of the model is constructed by incorporating the well documented concept of modelling materials flowing downstream with an approach of modelling orders flowing upstream (modelling of feedback information). The model has an easily adaptable structure where rules (inventory policies) and model variables can be modified. The flexibility in the model's structure allows devising appropriate experimental designs, for several tests to be performed to imitate some realistic situations or scenarios (including the presence of disturbances). A new control theory oriented inventory policy, called the pseudo PID, is proposed. Detailed evaluations of five inventory policies for a production-inventory control under dynamic and stochastic conditions is presented. The findings demonstrate the ability of the approach to provide a wealth of potential solutions to the decision-maker, and confirm the qualitative behaviour of a supply chain in response to the different policies

Combined ultrasound and IVU for the management of childhood urolithiasis: a case report

The incidence of ureteric calculus as a cause for severe abdominal pain in children is mounting, especially in the tropical country. The course of illness may be non-specific but a swift detection via non-invasive imaging modalities singly or in combination may avert unnecessary radiation hazard and futile surgery in a young child. In this paper, we discussed a case of an 11 year-old boy who was presented with a sudden onset of the right side severe abdominal colic whose a bedside ultrasound was positive for hydronephrosis for which localisation of stone was further confirmed via a low dose limited intravenous urography (IVU). It is important to note that data available on the value of a combined ultrasound and the limited IVU in an emergency setting when urolithiais is being suspected in children with abdominal pain are particularly scarce. Hence, this case documented the potential value of a combined ultrasound and a limited IVU study as a unique combined armamentarium used in a suspected childhood urolithiasis in the tropics

Lean manufacturing implementation: Developing a qualitative research design

Lean manufacturing have been widely used by manufacturing companies worldwide.However, low rate of success towards lean manufacturing transformation in many countries had created a cause of concern.Change agent system is a crucial element in lean transition as most of the employees are not familiar with lean work environment, and requires a behavioural and mindset change due to the different expectation for performance and value.This study attempts to investigate the role of change agent in the successful implementation of lean manufacturing. Qualitative case study approach is chosen as it offers a more holistic perspective.Therefore, the aim of this paper is to discuss on developing the research design in answering the research questions.A manufacturing company was selected. The four different methods for gathering data: interviews, observation, documents and focus group will contribute towards the categorization and code development process.This enabled a precise analytic approach to the study, which is an induction of highly specified and valid constructs concerning the knowledge development and conveyance process

State-space Modelling and Digital Controller Design for DC-DC Converter

The recent development in digital technology offers better platform for easy implementation of advance control algorithm in power converter design making digital control a viable alternative to analogue counterpart. Controller design for power converters has been very challenging due to non-linear characteristics of power switches, the supply voltage variability, load current changes and circuit element variation. This paper presents dynamic averaged state-space modelling of non-ideal dc-dc boost converter with parasitic and digital controller design for boost converter using digital redesign and direct digital design methods. The system was simulated in Matlab/Simulink to investigate the dynamic performance of the two controllers’ transient response, control bandwidth and response to variable supply voltage. The results demonstrated fast transient and wide control bandwidth for tight voltage regulation of variable input voltage

Phase-Shifted Full-Bridge Zero Voltage Switching DC-DC Converter Design with MATLAB/Simulink Implementation

Design of phase-shifted full bridge zero voltage switching DC-DC converter has been very challenging due to circuit parasitic effect on the system dynamics. This paper presents steady-state analysis and iterative approach for the systemic design of phase-shifted full bridge DC-DC converter with improved dynamic performance and satisfactory operational requirement in terms of zero-voltage switching range, operating switching frequency and switching resonance. A 3 kW DC-DC converter is designed using the iterative design approach and the system dynamics performance was investigated in the MATLAB/Simulink environment. The converter zero-voltage switching simulation results were satisfactory with 90% efficiency under full load condition

Physical and mechanical properties of concrete incorporating manufactured sand

Abstract. Concrete is a common material that widely used in construction industry. Excessive usage of this material causes exhaustibility to its components, especially fine aggregate or sand. In this regard, the use of manufactured sand is considered as a part of the solutions to fix this problem as it is readily available. In this research, the manufactured sand is used at 40%, 50% and 60% to replace natural river sand. SEM analysis reveals the rough surface texture of manufactured sand. The manufactured sand has angular shape and sieve analysis reveled that it has a considerable amount of fine particle. Slump test shows that concrete using manufactured sand pass the standard. On the other hand, compressive test shows that concrete cubes using manufactured sand do not achieved the target strength. Water absorptive test on the cubes revealed that M-Sand I has higher absorptivity property compared to river sand . SEM analysis revealed the existance of microcrack as well as porosity in in concrete cubes incorporating of manufactured sand. It can be concluded that it can be concluded that the higher the percentage of manufactured sand in the concrete mix the lower is the comprensive strength. Keywords: Manufactured sand; Concrete; Fine Aggregate; Compressive Strength; Workability; Water Absorption

Applications of 18(F) FDG PET/CT in oncology

The escalating costs of conventional diagnostic technology in oncology have yet to obviate futile surgery intervention and the spiralling treatment cost. The evolution in engineering technology which looks at the correlation of the anatomy and the function of tumours i.e. Positron Emission Tomography-Computed Tomography (PET-CT) have impacted on the improved diagnostic accuracy and treatment in oncology. Clinical data have demonstrated that the information provided by PET/CT often changes patient management. This review addresses the value of PET-CT as a surrogate molecular marker in tumours and to discuss some issues in adopting PET/CT in routine daily practice as supported by the numbers of literature reviews of its application in oncology since it was first commercialized in 2001. The description of the technology used in multimodality imaging has gained encouraging interest among physicians, policy makers and insurance companies on the importance of the PET-CT, for which roles are not limited to the staging, disease prognostication and treatment monitoring with potential impact on treatment cost and justification of radiation safety for the patient. PET/CT is a useful tool in cancer investigation as evidenced by its role as a surrogate marker in underpinning the cellular reprogramming of different pathological entities

Pattern of calcification on CT and FDG-PET of a rare perineural mantle cell lymphoma: a potential of non-histological imaging marker

The presence of calcification in a particular FDG-avid soft tissue lesion may at times present uncertainty regarding the clinical course of the disease pathology. Calcific deposits are not specific for either benign or malignant aetiologies (Brant et al., 2010). Altered glucose metabolism with associated calcification may underpin underlying aggressive pathophysiology with necrosis as sequelae. Mantle Cell Lymphoma (MCL) is a subtype of non-Hodgkin’s lymphoma. It is a rare B-cell NHL that is prevalent in men over the age of 60. The disease may be aggressive but it can also behave in a more indolent fashion in some patients. MCL comprises about 5% of all NHLs. The disease is called Mantle Cell Lymphoma because the tumour cells originally come from the ‘mantle zone’ of the lymph node (Zhou et al., 2004). Pretreatment Hodgkin’s lymphoma with calcification may masquerade as other second primary pathologies, e.g. extraosseous osteosarcoma or myositis ossificans (Apter et al., 2002; Korek-Amorosa et al., 1974). A calcified perineural lymphoma prior to treatment is exceedingly rare and calcification usually occurs one to five years after chemotherapy or radiation therapy with an incidence of 2% (Apter et al., 2002). This case documents how the manifestation of a rare malignant perineural mantle cell lymphoma may be indistinguishable from other pathological entities based on its pattern of distribution in a combined FDG-PET-CT study