Sharif Digital Repository

Tapering the beam along its length may lead to an increase in the voltage density of piezoelectric energy harvester. In this study, the energy harvester voltage with linear variable cross section is studied by developing an analytical method in both linear and nonlinear states. In linear mode, the results are compared with the experimental results. For the development of linear and nonlinear analytic relations, the Euler–Bernoulli beam and linear voltage variations in the thickness direction are used, and for the separation of variables, the mass normalized mode shapes has been used. The results of the linear analytical method are compared with the results of past research and experimental... 

Determining a promotion planning is a critical decision for retail managers. This plan should decide on the amount and duration of promotions for each product in a way that maximizes profit compared to a non-promotion scenario. In this study, the promotion optimization problem in a retail environment is formulated as a non-linear integer programming problem. The objective function is to maximize profit from product sales during the sales period. The problem also includes several business-related constraints that limit the number of promotions. In this study, a reinforcement learning approach, specifically Deep Q-Network, has been used to solve the mathematical model. The implementation... 

Pricing and revenue management are among the most important decisions for any economic enterprise. Several factors can influence decisions in this area and change the company’s pricing strategy, including uncertainties in product demand and customer preferences. This factor becomes particularly significant when the product is newly launched. Therefore, over time, customer preferences and willingness to pay may increase through various advertisements such as customer reviews and word-of-mouth. With rising demand, the seller has the opportunity to raise prices in the next periods. However, price increases can lead to unfair pricing perceptions by customers, hence reducing their purchasing... 

One of the important factors that are effective in the continuation of businesses is their profitability. Pricing, as an important component of the business process, greatly impacts profitability. Therefore, by using a suitable pricing method, retailers and service providers can increase their profits and avoid issues such as inventory congestion, imposed discounts, or lost sales opportunities. In this research, the two-tariff pricing system in internet services is investigated and determined by taking into account the randomness of customer consumption. The problem includes a set of Internet sales plans, each plan has a fixed price for a certain amount of data and a variable price for... 

The growing demand for scalable and cost-effective computing resources has led to the widespread adoption of the Infrastructure as a Service (IaaS) model in cloud computing. One of the pricing models for resources, or virtual machines, in this service is the Spot model, which allows customers to access unused cloud server capacity at significantly lower costs compared to other models. However, despite their affordability, these virtual machines do not come with a Service Level Agreement (SLA) and may experience interruptions during use. Such interruptions increase the time required for customers to complete their tasks. In this study, we utilize discrete-event system simulations to examine... 

Pricing plays an important and essential role in the profit and income of companies. The importance of pricing is not only related to its role in the company's profitability, but it also changes the customer's understanding and loyalty towards the company and can create the company's reputation or destroy it. Determining the right price will increase product sales and increase customer loyalty and create a competitive advantage for the company. One of the most important and influential variables in product pricing is the amount of demand. The main challenge of companies for product pricing is the uncertainty in their demand. In order to deal with this problem, data-driven pricing is used.... 

Coreference resolution is an essential step toward understanding discourses, and it is needed by many NLP tasks such as summarization, machine translation, question answering, etc. Pronoun resolution is a major and challenging subpart of coreference resolution, in which only the resolution of pronouns is considered. The existing coreference resolution approaches can be classified into two broad categories: linguistic and machine learning approaches. Linguistic approaches need a lot of linguistic information for the resolution process. Acquisition of such information is an error- prone and time-consuming process. In contrast, learning approaches need less linguistic information and provide... 

In network science, link prediction is one of the essential tasks that has been neglected. One important application of link prediction in telecommunication networks is analyzing the user's consumption pattern to provide better service. This project aims to predict future links with applications to call data using the users' call history. In previous research, there are two main approaches: 1) heuristic-based approach, and 2) deep-learning-based approach, such as graph neural networks. These methods are mainly used for processing static graphs, and therefore, we cannot generalize them to dynamic graphs. But there are many graphs which are dynamic in nature. For instance, call data records... 

In the upcoming research, with the aim of bone tissue engineering and achieving a new structure, a scaffold based on polyhema (PHEMA) and gelatin (Gel), which are biocompatible polymers for bone tissue, was made and evaluated. Also, in order to improve the bioactivity and mechanical properties, bioactive glass alone (BG45S5) or together with strontium (BG-Sr) was used in the scaffold structure. and chemical by conducting FTIR, XRD, SEM, mechanical strength, bioactivity measurement, contact angle, water absorption and degradation tests. Biological investigations were done using mesenchymal stem cells derived from human bone marrow and with the help of MTT evaluations and SEM photography. The... 

Although Robot Assisted Language Learning (RALL) has recently received attention as a tool for language learning, its role in pragmatic development has gone unnoticed. Hence, this study sought to explore the effect of RALL on pragmatic learning of greeting, thanking, and request speech acts by young Persian-speaking EFL learners. To this end, 38 preschool female and male kids (3-6 years old) were assigned to the RALL (19 students) and game-based (19 students) groups. The humanoid robot for the RALL group was used as an assistant to the teacher while for the game-based group the instruction was based on gaming methods such as command, mystery bag and pass the ball games. The instructional... 

Myocardial Infarction occurs due to sudden blockage in a coronary artery and causes necrosis of myocardial tissue. Since myocardium is unable to self-regenerate, cardiac tissue engineering has become a promising therapeutic approach for MI treatment by restoring heart function via combination of cells, biomaterials and signaling factors. For this purpose, myocardial extracellular matrix (ECM) is an attractive biomaterial providing better biomimetic for cultured cells. In this project, we synthesized an in situ forming hydrogel derived from myocardial ECM and for improving mechanical and electrical properties of ECM hydrogel we added oxidized alginate (OA) with 5% oxidation degree and APTMS... 

AZ91 is the most applicable alloy of magnesium alloys.Semisolid stir welding of AZ91 magnesium alloy was investigated due to its welding problem such oxide formation, hot cracking in weld metal, and high residual stress through solidification with special focus on the effect of the welding temperatures, stirring rates, and tool shape. The interlayer with thickness of 2mm was located between two AZ91 pieces with 7.5mm thickness. Then, they were heated to the desired temperatures (515C, 530C and 540C), the semisolid temperature of both base metal and interlayer. A grooved stirrer with six rotational speeds from 0rpm to 2000rpm was introduced into the stir weld seam and the welded coupons... 

In this thesis, the value-ladenness or value-neutrality of technology, new social media and as a result Instagram is investigated. It is also discussed whether values can be taken into account during the design process of technical artefacts, including new social media and Instagram, and methods are developed for this purpose. Several methods have been developed for this purpose, some of them and their compatibility with modern social media are explained; including the Value-Sensitive-Design method and the disclosive computer ethics design method. The frameworks of ethical philosophy such as virtue ethics are reviewed and the appropriate ethical framework for the analysis of new social media...