Sharif Digital Repository

We deal with primal-dual interior point methods for solving the linear programming problem.Taken from recent literature on interior point methods, we discuss a short-step and a long-step path-following primal-dual method and show how to have polynomial-time bounds for both methods. The iteration bounds are for the short-step variant and for the long-step variant. In the analysis of both variants, a new proximity measure is used, which is closely related to the Euclidean norm of the scaled search direction vectors. The analysis of the long-step method depends strongly on the fact that the usual search directions form a descent direction for the so-called primal-dual logarithmic barrier... 

The picosecond (ps) pulses in a synchronously pumped optical parametric oscillator (SPOPO) is generated by a 20W and 81.1 MHz Yb fiber laser at 1064nm, providing 11.7 W of total average power in near to mid-IR at 73% efficiency so that the signal pulse with a wavelength of 1560 nm and 7.1W average power and 3330 nm idler pulse with an average power of about 4.6W has been produced. The optical parametric oscillator (OPO), based on a 50 mm MgO:PPLN crystal with 5 gratings which is capable of withstanding large average powers without thermal effects.
The duration of these ultrashort infrared signal pulse generated by the described SPOPO is measured by using homemade interferometric... 

In recent years, requirement engineering and goal modeling have gained more attention among different organisations. Therefore, different methods have been designed to discover stakeholders’ requirements and translate them into process and organizational goals. Various goal models have been introduced to represent these goals and their relations towards each other. Still, these methods are manual representations of different process scenarios and do not relate to the actual behavior. In 2014, Map Miner Method (MMM) was introduced to discover intentional process models from event logs. MMM uses Hidden Markov Model (HMM) as a means to represent the process as a map model of strategies and... 

Dust explosions are a serious hazard in many process industries and storage facilities. More than 70% of dusts processed in industry are combustible. This implies that majority of industrial plants that have dust processing equipment are susceptible to dust explosions. Dust explosions pose the most serious and widespread of explosion hazards in the process industry alongside vapour cloud explosions (VCE) and boiling liquid expanding vapour explosions (BLEVE). Dust explosions almost always lead to serious financial losses in terms of damage to facilities and down time. They also often cause serious injuries to personnel, and fatalities. In this project we presented a systematic algorithm in... 

The tourism industry, as the world's largest industry, plays a significant role in the economic status of developing and developed countries, and has been among the fastest growing sectors in other industries in recent decades.The important role of the tourism industry in economic development has begun since the 19th century, but it has quickly traveled its course as a global industrial one.This rapid growth will enable us to exploit the potential of this industry with the growth of technology and knowledge.Designing a platform with the ability to link up the supply and demand among existing individuals as potential sources of resources to reduce the cost and facilitate tourism with a cheap... 

In this study, energy harvesting from stall flutter phenomenon of a NACA 0012 airfoil with the generator in the presence of a fixed cylinder in its upstream has been done. The airfoil can freely rotate along its center axis. Also, a spiral spring is attached to one end of the shaft to adjust the system's stiffness. For a parametric study, airfoil's shaft is set either in 25, 33 or 50 percent of its chord length from the leading edge, initial angle of attack from 0 to 24 with steps of 2 degrees, airstream velocity of tunnel in its test section from 6 to 16 meters per second with a step of 2, and cylinder horizontal and vertical location as well as its diameter are changed. Final goal of this... 

Recommending routes to city taxis in order to improve their performance in finding passengers can reduce traffic, pollution and waiting time for passengers, as well as this, increasing the efficiency of taxis can increase their income. In this study, by analyzing trajectory data obtained from 536 taxis in San Francisco over a period of one month, we generated networks of cells, each of which has time-dependent characteristics such as the probability of finding a passenger, the capacity of each cell, or the amount of demand exists is in the cell and the average speed of passing through that cell. also, the connections between these cells in order to make more use of the experiences of taxi... 

The purpose of the present study is to develop neural network estimation method for hybrid or panel data which have a combination of two cross-sectional and time series structures and because of the features of both structures, their use in different sciences offers many advantages; and the analytical methods for this data structure are also different from other one-dimensional structures, so different and specific regression models are presented for this data structure. However, in the artificial neural network method, modeling the development for this data structure is neglected, so in the present study, using the concepts of panel regression methods and their application to the... 

In this research, transient liquid phase (TLP) bonding of FSX-414 superalloy was investigated using MBF-80 interlayer. The bonding was performed at different temperatures (1050-1200oC) for various times (1-120min). Also, different gap sizes were studied using the interlayer with various thicknesses (25-100µm). Homogenizing treatment was performed at different temperatures (1175-1225oC) and times (1-6h) for the samples with complete isothermal solidification. The microstructure of the samples were studied using the optical, scanning electron and transmission electron microscopes. Also, XRD, SEM/EDS, SEM/WDS and TEM/EDS analyses were used to analyse the observed phases at the joints. To... 

Recent studies on inelastic behavior of soil-structure systems indicate that seismic design codes provisions, which use the same response modification factor for fixed base structures and soil-structure systems, are not appropriate and could lead to an increase in ductility demand of structures (as a part of soil-structure system). As a result, to reduce design base shear and design forces with regards to collaboration of soil-structure interaction could be in non-conservative manner. In all of these studies, the ductility component of the response modification factor (i.e. Rµ ) has been the major concern and the overstrength component has been ignored. However, the existence of... 

In the last decades, noticeable experimental and analytical investigations have been carried out on cast-in-place Reinforced Concrete column to Steel beam (RCS) connections, however rarely have been conducted on the precast RCS. In this reaserch, test results of five half-scale interior precast RCS connections with variable joint configurations are presented. The steel beams were connected to the precast column, using face bearing plates, embedded in the connection zone. The flanges of beams were strengthened with respect to scaled section, in order to increase the load transfer to the joint. All samples were loaded under reversed displacement controlled condition. The failure mode, joint...