A System Dynamics Approach to Comparative Analysis of Biomass Supply Chain Coordination Strategies

Biomass is one of the most efficient renewable energy sources to increase energy security and reduce the environmental issues. It could be utilised as back-up or main source of energy in off-grid remote northern communities of Canada, which are currently rely on fossil-fuels. However, small scale of energy demand, necessity of continuous energy supply, and spatial dispersion of such remote communities restrict the competitiveness and efficiency of bioenergy. Managing bioenergy supply chain from supplying biomass to conversion facilities is vital to overcome the challenges in expanding bioenergy production. In this sense, forming collaboration among the entities plays a key role to improve the economy of scale and efficiency of bioenergy production. In the literature, several coordination strategies resulted in varying impacts on entities’ profit or cost. As such, analyzing and comparing them in various conditions could assure selecting the most efficient one. This study recommends quantity discounts and cost-sharing coordination policies to promote the biomass level at communities in a cost-efficient manner through establishing bundling orders and benefiting the lower cost. This dissertation employs a system dynamics approach to simulate coordination scenarios and make the optimal decisions in a biomass supply chain including suppliers, hubs, and end-user. On that basis, performing a comparative analysis under various conditions and assumptions provide insights into the impact of coordination and selecting the preferred choice of coordination strategy for each player. The simulation-based optimization model is applied to a bioenergy supply chain case study in Canada’s off‐grid northern communities. The results of this research point to a significant role of coordination in improving the cost efficiency as well as the level of biomass-based energy production

Validity and reliability of oral picture-naming test in aphasic adults

Background and Aim: One of the common problems in many types of aphasia syndromes is word retrieval and/or production difficulty. So, designing a valid test that can examine this problem based on related processes and influencing factors is important. Picture confrontation naming is a typical method for assessing and treatment of word retrieval impairments. The aim of this study was determining the validity and reliability of oral picture-naming test in assessing word retrieval ability of aphasic adults.Methods: Content and face validity of the test, that contains the line drawings of 115 Persian nouns, were assessed by speech therapists, graphists and painters. Then, the test was administered on 10 aphasics and 30 age-, gender- and education-matched normal subjects in two steps. Construct validity and internal consistency of test were investigated. External consistency was analyzed by test-retest method.Results: The content and face validity of all items were more than 90 and 85 percents, respectively. There was a statistically significant difference between the mean scores of patients and normal subjects (p<0.001). The internal consistency of 0.98 was determined for the test. The intra-class correlation coefficient of this test was 0.98.Conclusions: The oral picture-naming test had good content, face and construct validity. Also, internal and external consistencies were high. So, this test is a valid instrument for assessing naming ability of aphasic patients by a variety and big set of picture