Sharif Digital Repository

The purpose of this study is to establish a lateral-torsional-axial dynamic model for spur and helical geared rotor systems subject to shaft bow manufacturing error. Timoshinko shaft element, elastic bearings and rigid disks used to simulate different element in the model. Tooth contacts is modeled with linear spring and damper along the pressure line.Results show that the vibration pattern of the unbalanced load and shaft bow effect is different. These obtained patterns might help with the fault diagnostics of rotating machinery. The vibration will be lowest if the unbalanced load and the shaft bow amplitude locates out of phase. The previous researches show that different pattern of the... 

The problem of jet into a cross flow is one of the classic problems in fluid mechanics and has many engineering applications, such as in vector thrust control systems. Although many works have been done in this field, there have not been enough research in interactions of supersonic jets into compressible subsonic cross flows (specially its interaction with control surfaces downstream). Hence, the purpose of this research is to get better understanding of this interaction and its effects on control surfaces downstream (both numerical and experimental). Some of the individual achievements of this research are the design and manufacturing of supersonic jet system, parametric study of: boundary... 

NiTi intermetallic is well known for its unique physical and mechanical properties, such as superelasticity, shape memory effect, good tribological properties, excellent corrosion resistance and biocompatibility. It is widely used in several areas including aerospace and medical applications and surface engineering. Several approaches, such as casting, powder metallurgy, self-propagating high-temperature synthesis, mechanical alloying and explosive shock-wave compression have been used to produce NiTi alloys. However the formation of the undesirable phases such as NiTi2 and Ni3Ti still is the biggest concern. According to Ni-Ti phase diagram, stability region of NiTi compound is at... 

With the rapid increase in the number of vehicles and the limitations on the extension of transportation network infrastructure, the need for utilizing proper methods to reduce traffic congestion has become increasingly important. One way to reduce traffic congestion is to control the signal splitting of traffic lights. Model predictive control (MPC) has been utilized so far by using different models of traffic flow dynamics in this field. Due to the high computational effort of MPC at each step time, the real-time implementation for large-scale networks has become a big challenge. Store-And-forward (SAF) is one of the traffic flow models that, due to its simplicity, makes it possible to... 

Continous blood glucose control has great importance for type 1 dyabetic patients. In this thesis, several types of controllers including: PI controller, model predictive controller base on state space model, linear model predictive controller base of linear input-output model and non-linear model predictive controller base of Hammerstein model have been used to regulate blood glucose of patients with type 1 diabetes. These models are identified using least squars method. Performance of these controllers is tested and the best one is introduced. For rejecting meal disturbances, a feedforward controller has been designed. Combination of feedback and feedforward controller would properly... 

In conventional method of modeling and design of structures it is assumed that structures are fixedly supported, however, this assumption is generally far from reality; because, not only the majority of buildings’ bases are not stiff enough to suppose them rigid, but also if their foundations are shallow there exist no piles underneath them, they may separate from their bases – the event which is called foundation uplift. Although according to past studies permission of foundation uplift as well as incorporation of base flexibility may markedly affect any structure’s dynamic response, is spite of about half a century which has elapsed since the beginning of these studies, it seems that still... 

This study aimed to model the cone penetration test using FLAC 2D software in order to investigate the silty soils that can be found in tailing dams. Additionally, the model of the direct simple shear test was built in the software to estimate the variation of liquefaction potential in these soils with in-situ conditions. It should be noted that the constitutive law used in this study was the NORSAND model which meets the requirements of modeling in both tests. After validating the models, several important parameters are considered as variables to examine their effects on the results of both experiments. Regarding the validation of the models, the constructed numerical models of the cone... 

Deformity is one of the common diseases of the spine. For example, in the case of scoliosis, which is a three-dimensional deviation in the spine, the prevalence of 2% to 32% among adults has been reported [1]. In case of severe deformity, surgical methods are usually used to correct it. In surgical methods, rods with appropriate curvature are placed next to the spine and the deviation is completely or partially corrected by connecting the vertebrae to said rods. In general, the curvature of the rods is determined based on the clinical indicators of the patient, the tissue fault strength, the stiffness of the soft tissues, the movement limitation of the vertebrae and the level of spinal cord... 

This research aims to explore the effectiveness of past tariff evolutions in shaping firms' response to current input prices. Additionally, it investigates how asymmetric fuel pricing across different industries influences overall industry efficiency and prosperity. Furthermore, the study examines the impact of fuel subsidies on the equilibrium distribution of companies independent of welfare decline. In Chapter 1, utilizing microdata from Iranian industrial workshops between 1386-1396 (2007-2017) A key finding is that new firms exhibit a significant and stronger reaction to energy price variations compared to other firms when it comes to technology choices.Chapter 2 presents a structural... 

Airlift pumps are devices for lifting liquid phase incorporating the gas phase to be injected in the bottom of the liquid column. Gas-liquid two-phase flow being the main part of the flow through these systems, flowing in vertical pipes of airlift pumps has different regimes namely bubbly, slug, churn and annular. Generally these regimes appear starting from bubbly to annular from bottom to top of the upriser pipe. Gas/liquid multiphase flows occur in a wide range of natural and man-made situations such as boiling heat transfer, cloud cavitation, bubble columns and reactors in the chemical industry, cooling circuits of power plants, spraying of liquid fuel and paint, emulsions, rain, bubbles... 

In recent decades, a wide range of research has been done on the characteristics of networks in various domains. Community structure is one of the most important properties in networks. However, most community detection methods designed for unipartite networks. Bipartite networks are very important in many different fields because these networks explicitly shows conceptual connections between different types of entities, for example in bioinformatics science, business, social and economic systems. Recently, community detection in bipartite networks has risen attention by the technical community, due to the accessibility of huge bipartite network data from different domains and the spread of...