Modeling of take-off and landing motion for a fixed wing (UAV) is necessary for developing an automatic take off and landing control system (ATOL). Automatic take off and landing system becomes an important system due to wide spread of unmanned aerial vehicles in different applications ranging from intelligence, surveillance, up to missile firing. Automatic take off and landing system reduces damage to an unmanned aerial vehicle and its payload that may be caused by human pilot errors. Furthermore, training human pilot to a sufficient level of skill and experience for takeoff and landing may take several years and significant cost. A human pilot also may impose additional restrictions for UAV operation especially at night time or dusty desert conditions. Although, ATOL adds complexity to the system, it reduces the long run cost and risk caused by takeoff and landing process, and makes UAV takeoff from different runways and at different atmospheric conditions. A mathematical model for takeoff is successfully developed for a small fixed wing UAV. A Matlab/Simulink simulation model is prepared for the ground roll phase, and some simulation results are also shown.

A numerical scheme for computing compressible multi-component flows is examined. The numerical approach is based on a mathematical model that considers interfaces between fluids as numerically diffused zones. The hyperbolic problem is tackled using a high-resolution HLLC scheme on a fixed Eulerian mesh. The scheme for the non-conservative terms is derived to fulfill the interface condition. The results are demonstrated for several one and two-dimensional test cases.

The aim of this work was to determine TTT diagram of medium carbon V-N micro-alloyed steel with emphasis on the

development of intragranular ferrite morphologies. The isothermal treatment was carried out at 350, 400, 450, 500, 550

and 600 οC. These treatments were interrupted at different times in order to analyze the evolution of the microstructure.

Metallographic evaluation was done using optical and scanning electron microscopy (SEM). The results show that at high

temperatures (≥ 500 ○C) polygonal intragranulary nucleated ferrite idiomorphs, combined with grain boundary ferrite and

pearlite were produced and followed by an incomplete transformation phenomenon. At intermediate temperatures (450, 500

○C) an interloced acicular ferrite (AF) microstructure is produced, and at low temperatures (400, 350 ○C) the sheave of

parallel acicular ferrite plates, similar to bainitic sheaves but intragranularly nucleated were observed. In addition to sheaf

type acicular ferrite, the grain boundary nucleated bainitic sheaves are observed.

The electron-doped magnetic nanoparticles of Ca1–xYxMnO3 (x = 0, 0.05, 0.10, 0.15, 0.20,

and 0.30) manganite with an average particle size of 50 nm are analyzed and discussed in relation to their bulk counterparts. Nanoparticle samples show dominant anti-ferromagnetic ordering with a significant increase of coercivity, with the maximum value of 0.9 T for x = 0.

Par ti cle size re duction in Ca1–xYxMnO3 retains the bulk-like magnetic behavior of samples

having up to 15% of Y3+, with the small fer ro mag netic contri bu tion from dis or dered sur face

spins. Sup pres sion of charge order ing state and en hance ment of sat ura tion mag ne ti zation

were found in samples with higher Y3+ con cen tra tion (x = 0.2, 0.3), indicating high ferromag netic contri bu tion in these sam ples

A new synthesis route for obtaining a single-phase hexagonal YMnO3 was developed, based on the annealing of the amorphous

precursor powder obtained by the glycine–nitrate combustion method. The process was monitored by XRD as well as by magnetic and

heat capacity measurements. The analysis of these data shows that precursor powder undergoes a gradual phase transformation that

depends on the annealing temperature. The metastable orthorhombic YMnO3 phase is the first to appear at temperatures below 700 1C,

while a mixture of ortho- and hexa-phases was found to exist within the 700–900 1C range. An almost complete conversion to hexaphase occurs at 900–1000 1C, but to obtain the pure, well crystallized h-YMnO3 phase an annealing temperature of 1300 1C was

necessary. The synthesis method applied in this work has been proved to be more convenient for obtaining single-phase h-YMnO3 than

by a solid state reaction. In addition, it is capable of producing sample free of parasitic phases that are often present in specimens

obtained by other synthesis methods.

Van Siclen (1988 Am. J. Phys. 56 1142) reported a curious property of a dielectric sphere in the field of an external point charge: the field outside the sphere generated by the combination of the original charge exterior and the Kelvin image charge interior to the sphere is independent of the permittivity of the sphere. In this paper, we simplify and correct the original derivation and give a detailed analysis of the sources of the field. We also present various checks for the theory, providing instructive exercises for advanced undergraduates.

The polymerization mechanism of methylol-functional benzoxazine monomers is reported using a series of monofunctional benzoxazine monomers synthesized via a condensation reaction of ortho-, meta-, or para-methylol–phenol, aniline, and paraformaldehyde following the traditional route of benzoxazine synthesis. A phenol/aniline-type monofunctional benzoxazine monomer has been synthesized as a control. The structures of the synthesized monomers have been confirmed by ¹H NMR and FT-IR. The polymerization behavior of methylol monomers is studied by DSC and shows an exothermic peak associated with condensation reaction of methylol groups and ring-opening polymerization of benzoxazine at a lower temperature range than the control monomer. The presence of methylol group accelerates the ring-opening polymerization to give the ascending order of para-, meta-, and ortho-positions in …

Fuzzy decision forests aim to improve the predictive power of single fuzzy decision trees by allowing multiple views of the same domain to be modelled. Such forests have been successfully created for classification problems where the outcome field is discrete; however predicting a continuous output value is more challenging in combining the output from multiple fuzzy decision trees. This paper presents a new approach to creating fuzzy regression tree forests based upon the induction of multiple fuzzy regression decision trees from one training sample, where each tree will represent a different view of the data domain. The singular fuzzy regression trees are induced using a proven algorithm known as Elgasir which fuzzifies crisp CHAID decision trees using trapezoidal membership functions for fuzzification and applies Takagi-Sugeno inference to obtain the final predicted values. A modified version of Artificial Immune System Network model (opt-aiNet) is then used for the simultaneous optimization of the membership functions across all trees within the forest. A strength of the proposed method is that data does not require fuzzification before forest induction this reducing pre-processing time and the need for subjective human experts. Five problem sets from the UCI repository and KEEL repository are used to evaluate the approach. The experimental results have shown that fuzzy regression tree forests reduce the error rate compared with single fuzzy regression trees.