Performance of thermostatic and electronic valves controlling the compressor capacity

The performance of the energy consumption of an electronic valve and a classical thermostatic valve has been compared when these expansion valves are adopted in a vapour compression plant subjected to a cold store. The main aim is to verify experimentally which type of expansion valve would be preferable from energy point of view when a classical thermostat or a fuzzy logic algorithm are used as the control system for the refrigeration capacity. The fuzzy logic‐based control is able to modulate continuously the compressor speed through an inverter. The results show that with a fuzzy algorithm, the thermostatic expansion valve allows an energy saving of about 8% in comparison with the electronic valve. When on–off control is used, the electric energy consumption obtained both with the electronic valve and with the thermostatic valve is comparable. Copyright © 2006 John Wiley & Sons, Ltd.     

Effect of surface waxes on the persistence of chlorpyrifos-methyl in apples, strawberries and grapefruits

The effects of the cuticle and epicuticular waxes of grapefruit, strawberry and apple on the photodegradation and penetration of chlorpyrifos-methyl were studied. Photodegradation experiments were conducted by exposing the insecticide to the light of a xenon lamp in the presence of a film of wax extracted from the fruit surface. The half-life of chlorpyrifos-methyl irradiated in absence of waxes was 9.6 min. The half-lives of pesticide irradiated in the presence of wax extracts of apple, grapefruit and strawberry were 83, 34 and 26 min, respectively. In penetration studies, fruit with and without wax layers were treated with an aqueous suspension of pesticide. The penetration of the pesticide from the cuticle to the pulp was measured after 24 h. Samples without wax contained a higher total amount of insecticide than those with wax. No pesticide was detected in samples of apple and grapefruit pulp. Residues were detected in all fractions of strawberry. The waxes and cuticle appear to have some effect on the photodegradation and penetration of chlorpyrifos-methyl in fruit samples.     

Fast Positive Feedback Between the Adrenocortical Stress Response and a Brain Mechanism Involved in Aggressive Behavior.

Aggressive behavior induces an adrenocortical stress response, and sudden stressors often precipitate violent behavior. Experiments in rats revealed a fast, mutual, positive feedback between the adrenocortical stress response and a brain mechanism controlling aggression. Stimulation of the aggressive area in the hypothalamus rapidly activated the adrenocortical response, even in the absence of an opponent and fighting. Hypothalamic aggression, in turn, was rapidly facilitated by a corticosterone injection in rats in which the natural adrenocortical stress response was prevented by adrenalectomy. The rapidity of both effects points to a fast, mutual, positive feedback of the controlling mechanisms within the time frame of a single conflict. Such a mutual facilitation may contribute to the precipitation and escalation of violent behavior under stressful conditions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Quasi-static stress fields for a crack inclined to the property gradation in functionally graded materials

Summary.  Quasi-static stress fields for a crack inclined to the direction of property gradation in functionally graded materials (FGMs) are obtained through an asymptotic analysis coupled with Westergaard's stress function approach. The elastic modulus of the FGM is assumed to vary exponentially along the gradation direction. The mode mixity due to the inclination of the property gradient is accommodated in the analysis through superposition of opening and shear modes. The first four terms in the expansion of the stress field are derived to explicitly bring out the influence of nonhomogeneity on the structure of the stress field. Using these stress field contours of constant maximum shear stress, constant maximum principal stress, constant first stress invariant and constant out of plane displacement are generated, and the effect of inclination of the property gradation direction on these contours is discussed. Received September 22, 2002 Published online: May 20, 2003 The financial support of National Science Foundation (NSF) under grant no. CMS 99000138 is gratefully acknowledged.     

Finding structure in audio for music information retrieval

This paper presents a brief overview of recent approaches to two problems in music information retrieval: query by example and automated source separation. It describes the challenges inherent in musical query by example and the systems that take very different approaches to the problem. The paper also explores approaches to source separation in a musical context, focusing on systems that take distinct approaches to the problem. Finally, it comments about the future directions for digital signal processing (DSP) research in the context of music information retrieval.     

Nonlinear crack dynamics and scaling aspects of fracture (experimental and theoretical study)

Nonlinear dynamics of crack propagation are investigated experimentally and theoretically with the goal of clarifying the nature of limiting crack velocity, the transition from steady state to branching regimes of crack dynamics, and the dynamics of crack arrest. The theoretical explanation of limiting steady-state crack velocity and the transition to a branching regime was proposed due to the study of collective behavior of a microcrack ensemble at the crack tip area. The experimental study of crack dynamics was carried out in a preloaded plate PMMA specimen using the high-speed camera coupled with the photo-elasticity method, the point stress recording with a laser system, and the failure surface roughness measurement.     

TEM Studies of High Temperature Corrosion Behaviour of TiAl Intermetallics with Surface Modifications

The oxidation/sulphidation behaviour of a Ti‐46.7Al‐1.9W‐0.5Si alloy with a TiAl₃ diffusion coating was studied in an environment of H₂/H₂S/H₂O at 850^oC. The kinetic results demonstrate that the TiAl₃ coating significantly increased the high temperature corrosion resistance of Ti‐46.7Al‐1.9W‐0.5Si. The SEM, EDX, XRD and TEM analysis reveals that the formation of an Al₂O₃ scale on the surface of the TiAl₃‐coated sample was responsible for the enhancement of the corroison resistance. The Ti‐46.7Al‐1.9W‐0.5Si alloy was also modified by Nb ion implantation. The Nb ion implanted and as received sampels were subjected to cyclic oxidation in an open air at 800^oC. The Nb ion implantation not only increased the oxidation resistance but also substantially improved the adhesion of scale to the substrate.