Sharif Digital Repository

In this thesis, manganese oxide nanoparticles with about 5 nm size were synthesized via solvothermal to maximize surface and active sites for proton relaxation. The synthesized nanoparticles were coated with gentisic acid to acquire suitable colloidal stability and biocompatibility. The nanoparticles showed low cytotoxicity in MTT assay. Electrosteric mechanisim was employed for colloidal stability. This mechanisim doesn’t need high surface charge and thick coat which are vital for particles functionality. Then by cell culture eliminating and adding protamine sulfade, nanoparticles uptake were increased tremendously. In this thesis for first time Prussian blue was utilized for staining... 

In recent years, economic globalization and resource globalization as two key factors have driven organizations to adjust their processes to survive in the competitive environments. Also, customers have been provided with high-quality products, lower cost, product customization and quick delivery. Moreover, globalization has let suppliers to geographically distribute across the globe, and for accomplishing the final product resources need to be gathered. Distributed infrastructure enables organizations to decrease delivery time and increase flexibility but leads to higher investment costs and lower efficiency of the system. For responding to existing issues Cloud manufacturing has been... 

Cloud computing is a service-driven business model that connects distributed resources and allows multiple service demaders to submit requests simultaneously to a cloud platform via the Internet. An important issue in cloud environments is how to allocate tasks to optimize the performance of a cloud manufacturing system. Allocation of tasks in cloud manufacturing refers to the process of selecting and assigning service providers to manufacturing resources such as design, engineering, machining, testing, and packing to achieve the satisfaction level in terms of time, cost, service availability, and other quality service criteria. Task allocation is an intrinsic part of the cloud manufacturing... 

Suppose that A is a large subset of N. It is interesting to think about the arithmetic progressions in A.In 1936, Erdos and Turan conjectured that for > 0 and k 2 N, there exists N = N(k; ) that for all subsets A {1; 2; : : : ;N}, if lAl N, A has a nontrivial arithmetic progression of length k. Roth proved the conjecture for k = 3 in 1953. In 1969, Szemeredi proved the case k = 4 and in 1975, he gave a combinatorial proof for the general case. In 1977, using ergodic theory, Furstenberg gave a different proof for the Erdos-Turan conjecture (or Szemeredi Theorem!) and finally Gowers found another proof for the Szemeredi theorem, which was an elegant generalization of the Roth’s proof for k =... 

In this thesis we introduce the objective method for solving combinatorial probability problems and combinatorial optimization. For introducing this method, we consider its application in solving problems such as graphs maximal partial matching problem. Then we introduce mean-field model, which has a close relationship with this method. Finally we use this method to discuss perfect mathching with minimal cost in complete graphs, and using obtaind theorems and concepts from solving this problem, like involution invariance and standard construction, we find an answer for random assigment problem, which is one of the most practical problems in the class of optimization problems  

New product development (NPD) is a crucial process in maintaining a company’s competitive position and succeeding in dynamic markets. One of contemporary trends in the global economy is mass customisation that bases on modifications of existing products instead of designing everything as a new project. Product development can be achieved in design, planning or production phases. Specifications of previous products deliver information of design, cost and time of past NPD projects that can be the basis for developing new products. Given the low chance of technical success, market change and high cost research, market demand, product development management is important to increase the quality... 

The purpose of this study was to investigate experimentally and modeling the process of gasification with supercritical water using waste motor oil. The effect of four important and influential parameters on the process, Temperature (350-450° C), Reaction time (15-45 minutes), Oil-to-Water volume ratio (0.2-0.4) and type of catalyst Consumption (Ni- NaOH- Na2CO3) was evaluated. Experimental experiments were designed and performed on the Design Expert software. The experimental results showed that the purity of hydrogen in the gas stream is more dependent on the temperature parameter and the higher purity is obtained with increasing temperature. Subsequently, as the oil concentration... 

In many fields of science, we observe a response variable together with a large number of potential explanatory variables, and would like to be able to discover which variables are truly associated with the response. At the same time, we need to know that the false discovery rate (FDR)—the expected fraction of false discoveries among all discoveries—is not too high, in order to assure the scientist that most of the discoveries are indeed true and replicable. This paper introduces the knockoff filter, a new variable selection procedure controlling the FDR in the statistical linear model whenever there are at least as many observations as variables. This method achieves exact FDR control in... 

Diseases such as cancer lead to extensive conversion in the biological structure of cells. These conversions can overshadow cell function. The dynamics of a cell directly depends on how it interacts with other cells and the extracellular environment. Most of these interactions are associated with the occurrence of mechanical phenomena and are due to forces that the cell has experienced. Cell mechanics manifests itself in the Mechanotransduction, the ability of a cell to sense and respond to external forces. Cancer alters the mechanical properties of the components of the cytoskeleton. Understanding the biomechanical behavior of cells and cytoskeleton can play an important role in early... 

Green project management involves a set of management actions to identify and evaluate the effect of activities on the environment along with controlling and improving performance.Accordingly, the concepts of lean, agility, and resilience have a special place as driving forces since they can play an important role in improving the environment. Thus, this study aimed to identify and prioritize the activities related to green project management considering the concepts of lean, agility, and resilience. The present study identified the dimensions of lean, agility, and resilience for the first time in green project management.Then, this study evaluated the prioritization of activities in terms... 

To reduce customer waiting times in various service conditions, admission control and service speedup can be implemented during times of congestion. In a healthcare setting, this may result in a patient being redirected to an alternative treatment facility. Additionally, waiting for patients can have negative impacts on their health and controlling population density can be costly. Implementing these measures may also take too much time or deviate from the ideal treatment. In this thesis, we will evaluate multi-server queuing systems by considering both speed and admission control simultaneously. We will use dynamic programming to determine the optimal control characteristics and calculate... 

In the era of the internet and with the emergence of online stores, the possibility of changing prices for these e-commerce platforms has become simple and virtually cost-free. This allows them to adjust prices optimally in response to environmental and surrounding factors, maximizing their revenue from product sales. This development has led to numerous applications of statistical learning methods, particularly online learning, in these markets. In this thesis, we explore the issue of online pricing from various perspectives. One aspect is that product pricing is based on their features, which can be numerous. This leads us to the use of online learning methods and statistical learning in... 

In photocatalitic activity of titana an effective approach to achieve high charge separation efficiency and high level of sensitivity under visible light is coupling it with another semiconductor with smaller band gap and appropriate banding energy structure. achieving all mentioned above, we used bilayer structure and coupled TiO2 with hematite which its small band gap(Eg ~ 2.1 ev) is sensitive to visible light. Bilayer systems of TiO2/Fe2O3 , Fe2O3/TiO2 were fabricated by sol-gel process and variable parameter was upper layer thickness. The layers were deposited on glass substrate via sol-gel process. The upper layers were prepared in different thicknesses in two ways. First, they... 

Doping metal or semiconductor nanoparticles in transparent matrix have attracted much attention for practical application in recent years. From fundamental veiw point, limiting the charge carriers and exitons in nanometric scales resulted in new quantum phenomena. In this context, transparent films containing metal nanoparticles shows an absorption peak in visible region of spectrom. Thus, by choosing an appropriate metal and controlling the size and concentration of particles in corresponding matrix, we can provide coatings with a wide rang of colors. Furthermore, thin films containing metal or metal oxide nanoparticles had been considered as nanostructure materials in research and... 

Chitosan (CS) is a natural polysaccharide, which is widely used for various biomedical applications due to its excellent properties such as biocompatibility, biodegradability, bioadhesivity, and bactericidal capacity. Nevertheless, the poor mechanical strength and the loss of structural integrity limit the applications of chitosan. Graphene oxide (GO) has been recognized as an ideal filler for reinforcement of a polymer matrix and its excellent water solubility makes it as a promising candidate for biopolymers. In this work, biocompatible chitosan-graphene oxide nanocomposites were synthesized. First, graphene oxide was prepared using modified Hummer’s method from graphite powder. Solvent... 

Competitive world of industrial production need more speed and faster reaction for the customer needs. This should be carried out in low cost activities while satisfying what the consumers and customers require. Business of commercial refrigerators and freezers is a big industry targeting small to big customers. In this thesis a systematic method relying on reduction of cost, reworking and unexpected expenditures in product life is utilized. Stands for Design for Manufacturing, DFM is a series of principles and guideline simply to achieve a faultless design of a product so that the non-incurred costs of the product travel through its life cycle become minimized. Freezers and refrigerators... 

In this research, the concept of new service development for Hotel industry is considered. As the concept of new service development encounters both business model structures and the required analysis for validation, the thesis has used the axiomatic design theory to evaluate the required service elements. Axiomatic Design framework as a scientific base for every type of design consists of 4 domains. The first domain named customer domain is the starting point at this research. In order to be prepared for applying in a real case study, customer domain is investigated and analyzed through a business model Canvas with nine building blocks covering all necessary and effective domains in a... 

This study, with integrated approach to the POM problem, has developed a linear mutual MILP model with the hybrid MTS / MTO operational approach on the OAS problem in industry 4.0 environment for the Shahin Plastic Manufacturing Company. This enabled an integrated PM with the production in the scheduling model. The model objective function has minimized costs and maximized the company profits. It also maximized customer satisfaction by minimizing the tardiness and earliness time in producing orders. To implement this model in the factory decision-making system, measures and modifications have been made to the MIS structure of the corporate departments. Measures include the creation of cloud... 

In this dissertation, we investigate the problem of the existence of finite geodetic sequences from point to point (0, n). This has not been proven in the general case. In this dissertation, we present an article that illustrates this question in a particular case of z ^ 2 subspaces whose self and complement are infinite and connected (e.g., slit planes, half-planes, and sectors). Writing x_n for the sequence of boundary vertices, we show that the sequence of geodesics from any point to x_n has an almost sure limit assuming only existence of finite geodesics. For all passage-time configurations, we show existence of a limiting Busemann function. Specializing to the case of the half-plane, we...