The Effects of Dimension Ratio and Horizon Length in the Micropolar Peridynamic Model

The aim of this study is to investigate the effects of horizon selection on the elastic behaviour of plate type structures in the micropolar peridynamic theory. Plates with various lengths and widths have been investi-gated using micropolar peridynamic model for different horizon selections. The mathematical model of plates has been provided applying the micropolar peridynamic theory and solution of this model has been obtained by finite element methods. The displacement fields have been computed for the different horizons and dimension ratios of plates. To compute the displacement field a program code has been developed by using the software package MATHEMATICA. The results obtained have been compared with the analytical solution of the classical elasticity theory and with the solution of displacement based finite element methods. For displacement based finite element method solution the software package ANSYS has been used. Ac-cording to results it has been observed that the displacement fields of the plates are strongly affected by ho-rizon selection. Therefore a question raises that which horizon length should be used with the problem in hand or is there any method to find the appropriate/best horizon length.

The Application of Ultra High Voltage in the World

With rapidly growth in industrial sectors, in order to meet the demand, the usage of Ultra High Voltage (UHV) is needed. High voltage (HV) is between the range of 52 kV and 300 kV. In case of voltage above 800 kV, it can be defined as UHV. With the development of technologies in the world, it could be seen that Japan, Russia, Italy, Brazil, America (U.S), and Canada began to improve UHV in the 1960s and 1970s. In addition, China, a leader developing country for UHV technologies in the world, started UHV technologies in transmission, in 1980s. Nowadays, seven transmission lines are in operation in China. In this study, the concept of HV and UHV will be introduced. Especially, UHV transmission in the worldwide will be researched. Then, the historical development and current situation of UHV will be analyzed and the assessment for Turkey will be done.

Power System Analysis of an Aero-Engine

The aim of this study is analyzed in detail for better understanding of energy and power of an aero-engine. In this regard, this study presents energy equations were applied to the turbofan engine components. The engine has a thrust range of 82 to 109 kN. It consists of fan, axial low pressure compressor (LPC), axial high pressure compressor (HPC), an annular combustion chamber, high-pressure turbine (HPT) and low pressure turbine (LPT). The results show that power of the engine flow approaches a maximum value to be 82.85 MW in the combustor outlet, while minimum power is observed at LPC inlet with the value of 1.37 MW. Furthermore, important parameters of the engine are also analyzed from reverse-engineering method. It is expected that results of this study will be beneficial of power, cogeneration and aero-propulsive generation systems in similar environment.

On Stability Delay Bounds of Simple Input-delayed Linear and Non-linear Systems: Computational Results

This paper deals with the problem of delay size stability analysis of single input-delayed linear and nonlinear systems. Conventional reduction, reduction linked by sliding mode, and linear memoryless control approaches are used for simple input-delayed systems to obtain the stability conditions. Several first order examples are investigated systematically to demonstrate the capabilities and limitations of the advanced stability analysis techniques including Lyapunov-Krasovskii functionals, Newton-Leibniz formula, and a newly addressed Lagrange mean value theorem. Numerical comparative results show the usefulness and effectiveness of the advanced delay size analysis techniques proposed in this paper.

Optimum Arrival Routes for Flight Efficiency

With the development of aircraft equipment, conventional navigation is the shift from performance based navigation (PBN). As is known, conventional navigation is based on ground-based navigation aids;however, PBN is based on aircraft avionics and performance. In this paper, a new method called Point Merge System (PMS) considered as one of PBN procedures will be introduced. PMS has many benefits related to fuel savings and emission reductions by implementing Continuous Descent Approaches (CDAs). A new PMS standard arrival route (STAR) model will be designed in radar simulation and it will be suggested.

Wind Turbine Tower Optimization under Various Requirements by Using Genetic Algorithm

The purpose of this study is to optimize the mass of 1.5 MW wind turbine steel tower performing Genetic Algorithm method (GA). In accordance with ASCE 7-98, AISC-89 and IEC61400-1 , the impact of loads on tower is calculated within the highest safety conditions against buckling strength of each sections of tower by means of GA codes. The stifness along tower is ensured entirely while the mass of tower is mitigated and optimized.

An Improved Genetic Algorithm for Crew Pairing Optimization

Crew pairing is a sequence of flights beginning and ending at the same crewbase. Crew pairing planning is one of the primary processes in airline crew scheduling;it is also the primary cost-determining phase in airline crew scheduling. Optimizing crew pairings in an airline timetable helps minimize operational crew costs and maximize crew utilization. There are numerous restrictions that must be considered and just as many regulations that must be satisfied in crew pairing generation. The most important regulations—and the ones that make crew pairing planning a highly constrained optimization problem—are the the limits of the flight and the duty periods. Keeping these restrictions and regulations in mind, the main goal of the optimization is the generation of low cost sets of valid crew pairings which cover all flights in the airline’s timetable. For this research study, We examined studies about crew pairing optimization and used these previously existing methods of crew pairing to develop a new solution of the crew pairing problem using genetic algorithms. As part of the study we created a new genetic operator—called perturbation operator.Unlike traditional genetic algorithm implementations, this new perturbation operator provides much more stable results, an obvious increase in the convergence rate, and takes into account the existence of multiple crewbases.

往复挤压对AA 6061/SiC复合材料力学性能的影响（英文）

使用往复挤压(RE)方法改善铸造和粉末冶金(PM)法制备的铝基复合材料的力学性能。分别使用AA 6063铸件和AA 6061粉末作为基体,使用5%SiC(体积分数)颗粒作为增强相制备复合材料。挤压样品的硬度和晶粒尺寸随挤压道次的增加而降低,而韧性和延展性随挤压道次的增加而增加。由于挤压样品的拉伸强度降低,其伸长率增加。因此,往复挤压是一种改善金属基复合材料(MMC)力学性能的有效方法。

N_(2)and Ar dilution on the premixed biogas jet flame under external acoustic enforcement

In this study,combustion instabilities and flue gas emission changes under different dilutions of N_(2)(nitrogen)and Ar(argon)of a promising biogas mixture(70%CH4-30%CO_(2))in the fight against greenhouse gas emissions were investigated.In the experiments,additions were made from 0%to 50%at intervals of 10%for both gases.In order to detect the instability of the flame,external acoustic enforcements at different frequencies was applied through the speakers placed in the combustion chamber arms.The dynamic pressure fluctuation values were recorded.The results showed that low dilution ratios were effective in reducing flame instability for both inert gases.However,as the dilution ratio increased,the fuel/air mixture became leaner and blowoff occurred.In the case of comparing two different gases,it has been observed that the effect of argon gas on reducing dynamic pressure fluctuation is higher.Burner outlet temperature and brightness values of the flame decreased in both Ar and N_(2)dilution.CO and NOx emissions increased with increasing diluent volume for all dilution conditions.When the emissions of the two diluent gases are compared,the CO emission,which was 3134 ppm in the undiluted condition,increased up to 4949 ppm in 50%Ar dilution,while it increased to 4521 ppm in 50%N_(2)dilution.

Unveiling the reaction products in heat treated Si3N4–Ti joined ceramics by transmission electron microscopy

Joining is a crucial process for the production of complex-shaped advanced engineering materials.Deep understanding of ceramic–metal interfaces during joining or following heat-treatment steps is therefore of important concern in designing the new systems.Capacitor discharge joining(CDJ)method was firstly carried out to compose the ceramic–metal joint material by silicon nitride(Si3N4)–titanium(Ti)constituents.Afterwards,heat treatment was performed on the Si3N4-Ti joints in air atmosphere at 1000℃temperature to reveal the interface reactions and phases.Reaction layer that occurred between the Si3N4 and Ti interfaces and new phase formations were examined by transmission electron microscopy(TEM)-based various imaging and chemical analysis techniques.Electron transparent samples for TEM characterization were prepared by focused ion beam(FIB)milling and lifting method.Based on the detailed TEM results,Si and N diffusion arising from the Si3N4 ceramic was observed towards Ti metal foil side and further interacted with Ti atoms.The upshot of current diffusion was that Ti3N2 reaction layer with 50 nm thickness was formed at the interface while titanium silicon nitride(Ti6Si3N)matrix phase including dendritic-shaped Ti2 N grains occurred in the Ti interlayer.It is believed that our TEM-based microscopy results not only provide the knowledge on ceramic–metal joint materials by CDJ method,but also contribute new insights on the development of various new joint systems.