فهرست مطالب امیر سیدعلیخانی

Applying the system dynamics approach in businesses requires specialized knowledge, in particular, of defining mathematical relationships among variables. This stud seeks to make the use of this approach easier by providing a method for using linguistic variables and the fuzzy inference system in the systems dynamics approach. To evaluate the ease of use and efficiency of the presented method, this method would be used to define the relationship among variables in the purchasing department of a distribution company.

To carry out this research, a literature review was first conducted in the field of fuzzy logic and system dynamics. Next, with the cooperation of an expert from the purchasing department of the distribution company under study, some fuzzy linguistic variables as well as their rules were determined. Finally, the SD model was obtained by using the fuzzy inference system.

The proposed approach can reflect the business dynamics of the distribution company in accordance with what is happening in practice. According to the feedback model feedback and based on the modified linguistic variables, appropriate values were obtained for decision making. In order to evaluate the hybrid approach, a fuzzy inference system was used to calculate the purchase rate according to the two factors of inventory and base sales. These two factors were expressed through linguistic variables by the words "low", "medium", and "high", while the purchase price, as the output of the inference system, was expressed through the five words "very low", "low", "medium", "much", and "too much", according to the expert. After implementing the model, the presented approach (by modifying the fuzzy linguistic variables) was found capable of changing the output to achieve the desired results, as the expert confirmed.

The combined approach can be used in simulating similar cases (where human factor perception and decision-making play a significant role) and can easily reduce the complexity of the required formulas in the system dynamics approach. An important function of the hybrid approach used in this study was to model and simulate the real world in accordance with what is happening in practice.

The main objective of this research is to present a model for analyzing various scenarios aimed at improving the status of startups by applying the hypotheses of one of the most practical courses of thought in this sphere namely the Lean Approach to Startups.The present research is regarded as applied in respect of the goal and with a descriptive nature based on the case study. Further, the research is a mixed type and based on the sequential exploratory strategy whereby in its qualitative section, the local group and in its quantitative section, the concept of customer attraction and reaction have been modelled by using the factor-based modelling approach and implementing the software of Netlogo 6.0.I for this purpose. In this regard, upon application of the various parts of this software, the model parameters were calibrated with real data and the outputs thereto were produced. Accordingly, by using the data analysis software, the produced outputs from Netlogo 6.0. I were aggregated and presented in the form of various indicator graphs. The research findings also prove that for the startups, being studied, the market operation of the customers who have recently consumed a product can increase the number of payers to over 30 percent relative to the attraction of new customers and about 40 percent relative to the market  operation of old customers. More importantly, the market operation of the customers having the highest relationships in their network will result in a 30-rise percent in the total number of customers. The main achievements of this research compared to the similar studies will be inclusion of the interaction structure among customers (their social network) in the modelling process, attention to homogeneity among customers as well as the credit rating of the model so produced.