Low computational cost CFD analysis of thermoacoustic oscillations

The numerical analysis of thermoacoustic oscillation phenomena by means of time-dependent CFD simulations usually requires a great computational effort, which may not be reasonable in industrial design. On the other hand, CFD tools provide the only approach that includes all the physical and chemical aspects involved in the thermoacoustic coupling between flame heat release and the acoustic modes of the burner/combustion chamber system. This paper presents some guidelines to reduce the computational effort required to perform a CFD analysis of the thermoacoustic oscillations with commercial codes. These guidelines are organized in a procedure that can be followed to analyze thermoacoustic coupling conditions that actually lead to unstable oscillations or are identified as potentially critical in the design phase. This procedure is also illustrated by an example of application, the partially-premixed flame type burner of a real 10 MW industrial boiler which shows noisy pressure fluctuations at a low frequency.     

Disaster-survivable cloud-network mapping

Cloud-computing services are provided to consumers through a network of servers and network equipment. Cloud-network (CN) providers virtualize resources [e.g., virtual machine (VM) and virtual network (VN)] for efficient and secure resource allocation. Disasters are one of the worst threats for CNs as they can cause massive disruptions and CN disconnection. A disaster may also induce post-disaster correlated, cascading failures which can disconnect more CNs. Survivable virtual-network embedding (SVNE) approaches have been studied to protect VNs against single physical-link/-node and dual physical-link failures in communication infrastructure, but massive disruptions due to a disaster and their consequences can make SVNE approaches insufficient to guarantee cloud-computing survivability. In this work, we study the problem of survivable CN mapping from disaster. We consider risk assessment, VM backup location, and post-disaster survivability to reduce the risk of failure and probability of CN disconnection and the penalty paid by operators due to loss of capacity. We formulate the proposed approach as an integer linear program and study two scenarios: a natural disaster, e.g., earthquake and a human-made disaster, e.g., weapons-of-mass-destruction attack. Our illustrative examples show that our approach reduces the risk of CN disconnection and penalty up to 90 % compared with a baseline CN mapping approach and increases the CN survivability up to 100 % in both scenarios.     

Radiant floors integrated with PCM for indoor temperature control

The control of indoor thermal comfort in buildings through thermal inertia during the summer season plays a fundamental role in the design of energy efficient buildings, especially in the Mediterranean climate. In fact, lightweight, highly insulated buildings cannot provide the necessary mass to buffer thermal gains. Phase change materials (PCM) have been used to provide lightweight building components with the required thermal inertia without increasing their overall mass. So far the integration of PCM into lightweight piped radiant floors for the control of thermal comfort during summer cooling regimes has not been investigated. This paper reports the development of a lightweight piped radiant floor prototype with an integrated PCM layer aimed at buffering internal gains at constant temperature during summer cooling regimes without affecting its winter warming capacity. Both the construction of the laboratory specimens and the development of the optimized finite element models are detailed and the assessment of the floor performance in a simulated room is discussed.     

Recovery of anthocyanins from eggplant peel

Tartaric and malic acid solutions were tested to extract anthocyanins from eggplant peel by a discontinuous process to obtain a natural red colorant. Extraction optimization was carried out, using different solvents, acid concentration, temperature, time of extraction and solvent-to-solid ratio as independent variables. Tartaric acid was more efficient than malic acid in both extraction yield and rate. Comparative tests were carried out using acidified ethanol as solvent. Delphinidin-3-rutinoside was extracted and identified as the major anthocyanin in eggplant peel. Concentration of different extracts from eggplant peel was carried out using EXA-31, a methacrylic food grade resin, the best performing resin to obtain highly concentrated extracts.     

Changes in self-control problems and attention problems during middle school predict alcohol, tobacco, and marijuana use during high school.

Although deficits in impulse control have been linked to adolescent use of alcohol and illicit drugs, less attention has been given to variability in change in impulse control across adolescence and whether this variability may be a signal of risk for early substance use. The goals of the current study were to examine growth in two aspects of impulse control, self-control problems and attention problems, across middle adolescence, and to test the prospective effects of level and change in these variables on levels and change over time in substance use. Data are from a community sample of 955 adolescents interviewed (along with their parents and teachers) annually from 6th to 11th grade. Results indicated that greater self-control problems and attentional problems in the 6th grade and increases in these problems over time were associated with higher levels of substance use at 11th grade. Our results suggest that modeling change over time enhances the understanding of how impulse control influences the development of substance use. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The effect of relative humidity on the gas permeability and swelling in PFSI membranes

The permeation of helium, oxygen and nitrogen in perfluorosulphonic acid ionomeric (PFSI) membranes with short and long side chains, namely Aquivion^® and Nafion^® 117, was studied in the relative humidity range between 0 and 90%, and at temperatures between 35 °C and 65 °C. The presence of humidity enhances, up to a factor of 100, the gas permeability in the membranes, due to the permeation of gas molecules in the hydrophilic domains: the enhancement is rather pronounced for O₂ and N₂, and less marked for He permeability. The relative permeability increase, P_gas/P_gas,0, shows a complex dependence on the relative humidity, as the water content in the membrane is itself a non linear function of this parameter. The water volume fraction in the membrane at each activity was accurately estimated from measurements of vapor-induced swelling, which indicate that the partial molar volume of water is smaller than its pure liquid value, in both membranes at 35 °C. When plotted against water volume fraction, the gas permeability increases exponentially in the range between 2% and 20%; the slope of the curve is higher for Nafion^® than for Aquivion^®, as it is reasonable due to their different microstructures. The ideal selectivity of the two membranes for He over N₂, O₂ over N₂ and He over O₂, decreases markedly with increasing water content in the membrane.     

The Rovereto Emotion and Cooperation Corpus: a new resource to investigate cooperation and emotions

The Rovereto Emotion and Cooperation Corpus (RECC) is a new resource collected to investigate the relationship between cooperation and emotions in an interactive setting. Previous attempts at collecting corpora to study emotions have shown that this data are often quite difficult to classify and analyse, and coding schemes to analyse emotions are often found not to be reliable. We collected a corpus of task-oriented (MapTask-style) dialogues in Italian, in which the segments of emotional interest are identified using psycho-physiological indexes (Heart Rate and Galvanic Skin Conductance) which are highly reliable. We then annotated these segments in accordance with novel multimodal annotation schemes for cooperation (in terms of effort) and facial expressions (an indicator of emotional state). High agreement was obtained among coders on all the features. The RECC corpus is to our knowledge the first resource with psycho-physiological data aligned with verbal and nonverbal behaviour data.