Social Media Marketing – Overview
Business in today’s day and age is dominated by customers and their demands. People prefer to see referrals, reviews over Google search results, or a website before purchasing a product.…
ALUMINIUM
It is present on the surface of earth crust in most of the rooks and clay. But to produce the metal bauxite (Al2O3. 2H2O) is ideally suited ore. Properties of…
Introduction to Power Generation and Distribution System for a More Electric Aircraft
More-Electric Aircraft (MEA) is the future trend in adopting single power type for driving the non-propulsive aircraft systems; i.e. is the electrical power. The MEA is anticipated to achieve numerous advantages such as optimising the aircraft performance and decreasing the operation and maintenance costs. Moreover, MEA reduces the emissions of air pollutant gases from aircrafts, which can contribute in signifcantly solving some of the problems of climate change. However, the MEA puts some challenges on the aircraft electrical system, both in the amount of the required power and the processing and management of this power. This chapter introduces the outline for MEA. It investigates possible topologies for the power system of the aircraft. The different electric power generation options are highlighted; while at the same time assessing the generator topologies. It also includes a general review of the power electronic interfacing circuits. Also, the key design requirements for an interfacing circuit are addressed. Finally, a glance at protection facilities for the aircraft power system is given. More electric aircraft Recently, the aircraft industry has achieved a tremendous progress both in civil and military sectors (AbdElhafez & Forsyth, 2008,2009; Cronin, 1990; Moir & Seabridge, 2001). For example some current commercial aircraft operate at weights of over 300 000 kg and have the ability to fly up to 16 000 km in non-stop journey at speed of 1000 km/h (AbdElhafez & Forsyth, 2009). The non-propulsive aircraft systems are typically driven by a combination of different secondary power drives/subsystems such as hydraulic, pneumatic, electrical and mechanical (AbdElhafez & Forsyth, 2008,2009; Jones, 1999; Moir, 1999; Moir & Seabridge, 2001; Quigley, 1993). These powers subsystems are all soured from the aircraft main engine by different methods. For example, mechanical power is extracted from the engine by a…
Introduction to Subjective Factors in Flight Safety
The central deterministic element of the aircraft conventional control systems is the pilot – operator. Such systems are called as active endogenous subjective systems, because (i) the actively used control inputs (ii) origin from inside elements (pilots) of the system as (iii) results of operators’ subjective decisions. The decisions depend on situation awareness, knowledge, practice and skills of pilot-operators. They may make decisions in situations characterized by a lack of information, human robust behaviors and their individual possibilities. These attributes as subjective factors have direct influences on the system characteristics, system quality and safety. Aircraft control containing human operator in loop can be characterized by subjective analysis and vehicle motion models. The general model of solving the control problems includes the passive (information, energy - like vehicle control system in its physical form) and active (physical, intellectual, psychophysiology, etc. behaviors of subjects - operators) resources. The decision-making is the appropriate selection of the required results leading to the best (effective, safety, etc.) solutions. This chapter defines the flight safety and investigates aircraft stochastic motion. It shows the…
Introduction to GNSS Carrier Phase-Based Attitude Determination
The GNSS (Global Navigation Satellite Systems) are a valid aid in support of the aeronautic science. GNSS technology has been successfully implemented in aircraft design, in order to provide accurate position, velocity and heading estimations. Although it does not yet comply with aviation integrity requirements, GNSS-based aircraft navigation is one of the alternative means to traditional dead-reckoning systems. It can provide fast, accurate, and driftless positioning solutions. Additionally, ground-based GNSS receivers may be employed to aid navigation in critical applications, such as precision approaches and landings. One of the main issues in airborne navigation is the determination of the aircraft attitude, i.e., the orientation of the aircraft with respect to a defined reference system. Many sensors and technologies are available to estimate the attitude of a aircraft, but there is a growing interest in GNSS-based attitude determination (AD), often integrated at various levels of tightness to other types of sensors, typically Inertial Measurements Units (IMU). Although the accuracy of a stand-alone GNSS attitude system might not be comparable with the one obtainable with other modern attitude sensors, a GNSS-based system presents several advantages. It is inherently driftless, a GNSS receiver has low power consumption, it requires minor maintenance, and it is not as expensive as other high-precision systems, such as laser gyroscopes. GNSS-based AD employs a number of antennas rigidly mounted on the aircraft’s structure, as depicted in Figure 1. The orientation of each of the baselines formed between the antennas is determined by computing their relative positions. The use of GNSS carrier phase signals enables very precise range measurements, which can then be related to angular estimations. However, carrier phase measurements are affected by unknown integer ambiguities, since only their fractional part is measured by the receiver. The process of reconstructing the number of whole cycles from a set of measurements affected by errors goes under the name of ambiguity resolution (AR). Only after these ambiguities are correctly resolved to their correct integer values, will reliable baseline measurements and attitude estimations become available. This chapter focuses on novel AR and AD methods. Recent advances in GNSS-based attitude 2 Will-be-set-by-IN-TECH determination have demonstrated that the two problems can be formulated in an integrated manner, i.e., aircraft attitude and the phase ambiguities can be considered as the unknown parameters of a common ambiguity-attitude estimation method. In this integrated approach, the AR and AD problems are solved together by means of the theory of Constrained Integer Least-Squares (C-ILS). This theory extends the well-known least-squares theory (LS), by having geometrical constraints as well as integer constraints imposed on parameter subsets. The novel AR-AD estimation problem is discussed and its various properties are analyzed. The method’s complexity is addressed by presenting new numerical algorithms that largely reduce the required processing load. The main objective of this chapter is to provide evidence that: • GNSS carrier-phase based attitude determination is a viable alternative to existing attitude sensors • Employing the new ambiguity-attitude estimation method enhances ambiguity resolution performance • The new method can be implemented such that it is suitable for real-time applications The structure of this contribution is as follows. Section 2 gives the observation and stochastic model which cast the set of GNSS observations, with special focus on the derivation of the GNSS-based attitude model. Section 3 reviews the most common attitude parameterization and estimation methods, mainly focusing on those widely used in aviation applications. Section 4 introduces a new ambiguity-attitude estimation method, which enhances the existing approach for attitude determination using GNSS signals. Section 5 presents flight-test results, which provide practical evidence of the novel method’s performance. Finally, section 6 draws several conclusions. Fig. 1. GNSS data collected on multiple antennas installed on the fuselage and wings allow the estimation of an aircraft’s orientation (attitude). The GNSS-based attitude model…
Introduction to Influence of Forward and Descent Flight on Quadrotor Dynamics
The focus of this chapter is an aircraft propelled with four rotors, called the quadrotor. Quadrotor was among the first rotorcrafts ever built. The first successful quadrotor flight was recorded in 1921, when De Bothezat Quadrotor remained airborne for two minutes and 45 seconds. Later he perfected his design, which was then powered by 180-horse power engine and was capable of carrying 3 passengers on limited altitudes. Quadrotor rotorcrafts actually preceded the more common helicopters, but were later replaced by them because of very sophisticated control requirements Gessow & Myers (1952). At the moment, quadrotors are mostly designed as small or micro aircrafts capable of carrying only surveillance equipment. In the future, however, some designs, like Bell Boeing Quad TiltRotor, are being planned for heavy lift operations Anderson (1981); Warwick (2007). In the last couple of years, quadrotor aircrafts have been a subject of extensive research in the field of autonomous control systems. This is mostly because of their small size, which prevents them to carry any passengers. Various control algorithms, both for stabilization and control, have been proposed. The authors in Bouabdallah et al. (2004) synthesized and compared PID and LQ controllers used for stabilization of a similar aircraft. They have concluded that classical PID controllers achieve more robust results. In Adigbli et al. (2007); Bouabdallah & Siegwart (2005) "Backstepping" and "Sliding-mode" control techniques are compared. The research presented in Adigbli et al. (2007) shows how PID controllers cannot be used as effective set point tracking controller. Fuzzy based controller is presented in Varga &…
Introduction to Study of Advanced Materials for Aircraft Jet
Engines Using Quantitative Metallography The aerospace industry is one of the biggest consumers of advanced materials because of its unique combination of mechanical and physical properties and chemical stability. Highly alloyed stainless steel, titanium alloys and nickel based superalloys are mostly used for aerospace applications. High alloyed stainless steel is used for the shafts of aero engine turbines, titanium alloys for compressor blades and finally nickel base superalloys are used for the most stressed parts of the jet engine – the turbine blades. Nickel base superalloys were used in various structural modifications: as cast polycrystalline, a directionally solidified, single crystal and in last year’s materials which were produced by powder metallurgy. So what exactly is a superalloy? Let us have a closer look to its definition. An interesting thing about it is that there is no standard definition of what constitutes a superalloy. The definitions which are provided in the various handbooks and reference books, although somewhat vague, are typically based on the service conditions in which superalloys are utilised. The most concise definition might be that provided by Sims et al. (1987):…
Introduction to Variational Approach to the Fuel Optimal
Control Problem for UAV Formations The pivotal role of unmanned aerial vehicles (UAVs) in modern aircraft technology is evidenced by the large number of civil and military applications they are employed in. For example, UAVs successfully serve as platforms carrying payloads aimed at land monitoring (Ramage et al., 2009), wildfire detection and management (Ambrosia & Hinkley, 2008), law enforcement (Haddal & Gertler, 2010), pollution monitoring (Oyekan & Huosheng, 2009), and communication broadcast relay (Majewski, 1999), to name just a few. A formation of UAVs, defined by a set of vehicles whose states are coupled through a common control law (Scharf et al., 2003b), is often more valuable than a single aircraft because it can accomplish several tasks concurrently. In particular, UAV formations can guarantee higher flexibility and redundancy, as well as increased capability of distributed payloads (Scharf et al., 2003a). For example, an aircraft formation can successfully intercept a vehicle which is faster than its chasers (Jang & Tomlin, 2005). Alternatively, a UAV formation equipped with interferometic synthetic aperture radar (In-SAR) antennas can pursue both along-track and cross-track interferometry, which allow harvesting information that a single radar cannot detect otherwise (Lillesand et al., 2007). Path planning is one of the main problems when designing missions involving multiple…
Introduction to One Dimensional Morphing Structures for Advanced Aircraft
Since the Wright Brothers’ first flight, the idea of “morphing” an airplane’s characteristics through continuous, rather than discrete, movable aerodynamic surfaces has held the promise of more efficient flight control. While the Wrights used a technique known as wing warping, or twisting the wings to control the roll of the aircraft (Wright and Wright, 1906), any number of possible morphological changes could be undertaken to modify an aircraft’s flight path or overall performance. Some notable examples include the Parker Variable Camber Wing used for increased forward speed (Parker, 1920), the impact of a variable dihedral wing on aircraft stability (Munk, 1924), the high speed dash/low speed cruise abilities associated with wings of varying sweep (Buseman, 1935), and the multiple benefits of cruise/dash performance and efficient roll control gained through telescopic wingspan changes (Sarh, 1991; Gevers, 1997; Samuel and Pines, 2007). While the aforementioned concepts focused on large-scale, manned aircraft, morphing technology is certainly not limited to vehicles of this size. In fact, the development of a new generation of unmanned aerial vehicles (UAVs), combined with advances in actuator and materials technology, has spawned renewed interest in radical morphing configurations capable of matching multiple mission profiles through shape change – this class has come to be referred to as “morphing aircraft” (Barbarino et al., 2011). Gomez and Garcia (2011) presented a comprehensive review of morphing UAVs. Contemporary research is primarily…
Helicopter rotor
A helicopter main rotor or rotor system is the combination of several rotary wings (rotor blades) and a control system that generates the aerodynamic lift force that supports the weight of the helicopter, and the thrust that counteracts aerodynamic drag in forward flight.…
