Testing of felt-ceramic materials for combustor applications

The feasibility of using composite felt ceramic materials as combustor liners was experimentally studied. The material consists of a porous felt pad sandwiched between a layer of ceramic and one of solid metal. Flat, rectangular test panels, which encompassed several design variations of the basic composite material, were tested, two at a time, in a premixed gas turbine combustor as sections of the combustor wall. Tests were conducted at combustor inlet conditions of 0.5 MPa and 533 K with a reference velocity of 25 m/s. The panels were subjected to a hot gas temperature of 2170 K with 1% of the total airflow used to film cool the ceramic surface of the test panel. In general, thin ceramic layers yield low ceramic stress levels with high felt ceramic interface temperatures. On the other hand, thick ceramic layers result in low felt ceramic interface temperatures but high ceramic stress levels. Extensive thermal cycling appears to cause material degradation, but for a limited number of cycles, the survivability of felt ceramic materials, even under extremely severe combustor operating conditions, was conclusively demonstrated

POTENTIAL ANALYSIS OF RAINFALL-INDEXED INSURANCE IN ROMANIA

One of the key factors affecting the crop output is the rainfall volume. For this reason, insurance plans based on the rainfall deviation of the mean have been advanced. This paper provides prospects of rainfall-indexed insurance in Romania considering the tradeoff between moral hazard and basis risks. The reasonability of rainfall-indexed insurance will be judged first. The basic parameters will then be determined and the effectiveness will be measured. Finally, microfinance programs combined with indexed insurance will be advanced to deal with the basis risk problems, which also are the goals for further studyRisk and Uncertainty,

Experimental and theoretical control of a smart projectile fin using piezoelectric bimorph actuator

The goal of this work is to develop efficient control algorithms for the control of a smart projectile fin. Smart fins are deployed as soon as the projectile reaches the apogee and are used to steer the projectile towards its target by controlling the rotation angle of the fin. The fin is actuated using the piezoelectric macro-fiber composite (MFC) bimorph actuator which is completely enclosed within the aero-shell. The actuator is composed of two Macro Fiber Composites (MFC\u27s), manufactured by Smart Material Co. The presented smart fin design minimizes the volume and weight of the unit; Two different models of the smart fin are developed. One is mathematical model that uses finite element approach to describe dynamics of the smart fin system. This model includes the aerodynamic moment which is a function of the angle of attack of the projectile. Second model is based on system identification approach. A linear model of the actuator and fin is identified experimentally by exciting the system using a chirp signal. Comparison is done between these two models based on open-loop step response of the smart fin system; In this dissertation, five kinds of control systems based on fuzzy logic, inverse dynamics and adaptive structure theory are developed. The aerodynamic disturbances and parameter uncertainties are considered in these controllers. The simulation results illustrate that asymptotic trajectory tracking of the fin angle is achieved, in spite of uncertainties in the system parameters and presence of aerodynamic disturbance. A prototype model of the projectile fin is developed in the laboratory for real-time control. The designed controllers are validated using the subsonic wind tunnel at University of Nevada, Las Vegas (UNLV) for various wind speeds. Experimental results show that the designed controllers accomplish fin angle control

Surface acoustic wave hydrogen sensor

The present invention provides a delay line SAW device fabricated on a lithium niobate substrate and coated with a bilayer of nanocrystalline or other nanomaterials such as nanoparticles or nanowires of palladiumn and metal free pthalocyanine which will respond to hydrogen gas in near real time, at low (room) temperature, without being affected by CO, O.sub.2, CH.sub.4 and other gases, in air ambient or controlled ambient, providing sensitivity to low ppm levels