SMART Sprinkler Protection for Highly Challenging Fires—Part 1: System Design and Function Evaluation

An experimental study was conducted to prove the concept of a new protection system—a sprinkler system that uses Simultaneous Monitoring, Assessment and Response Technology (SMART). The present work focuses on the system design and function evaluation at the component level. The objective is to demonstrate the feasibility that the SMART sprinkler system can provide adequate protection to highly challenging fires. The new protection system has several key functions including multi-sensor detection, real-time fire location calculation, dynamic sprinkler activation and wireless communication coordinating the system components. A series of fire detection, sprinkler activation and fire suppression tests were carried out to evaluate these system functions. Results show that a combination of smoke and temperature sensors can detect the fire at a very early stage, with the fire size reduced by one order of magnitude, and provide sufficient data to locate the fire. A thermal centroid based algorithm can determine the fire location within less than 50% of the sprinkler spacing on average. The sprinkler activation (six units) concentrating water discharge in the vicinity of the fire can suppress and even extinguish the fire under certain experimental conditions. These results confirm that the design objectives have been achieved. The experimental data also provide crucial information to assess system performance in full-scale tests.     

Office workers' computer use patterns are associated with workplace stressors

This field study examined associations between workplace stressors and office workers' computer use patterns. We collected keyboard and mouse activities of 93 office workers (68F, 25M) for approximately two work weeks. Linear regression analyses examined the associations between self-reported effort, reward, overcommitment, and perceived stress and software-recorded computer use duration, number of short and long computer breaks, and pace of input device usage. Daily duration of computer use was, on average, 30 min longer for workers with high compared to low levels of overcommitment and perceived stress. The number of short computer breaks (30 s–5 min long) was approximately 20% lower for those with high compared to low effort and for those with low compared to high reward. These outcomes support the hypothesis that office workers' computer use patterns vary across individuals with different levels of workplace stressors.     

Laminar flame speed measurements of dimethyl ether in air at pressures up to 10 atm

Laminar flame speed measurements of dimethyl ether/air mixtures were made at 1, 5, and 10 atm with equivalence ratios ranging from 0.7 to 1.6. All experiments were performed in a large cylindrical constant-volume bomb with optical access. A new method for converting flame images into flame radii was used. Results reported in other studies were investigated, and some explanations on the disparities found are presented. A full uncertainty analysis was performed combining precision errors from data scatter with predicted systematic errors. Uncertainties ranging between 4.2% and 8.6% were found depending on the equivalence ratio and initial pressure. Experimental results agreed well with some other spherical flame experiments and counterflow flame measurements, but were found to be much lower than PIV-based stagnation flame results. Also, two spherical flame studies deviated significantly both in magnitude and trend. Critical radii and Peclet numbers, defined by the onset of rapid flame acceleration, were recorded for all high-pressure experiments. Markstein lengths were measured and showed a decreasing trend with increasing equivalence ratio. Three different methods were used to define the laminar flame thickness, and large disparities were found between them. In this study, the modeled temperature gradient method for the definition of flame thickness is preferred over other methods. Modeling was performed with the latest version of a C3 chemical kinetics mechanism. Good agreement is seen between the experimental results and the model at all pressures. Emphasis is placed in this paper on reporting experimental uncertainties, calculated density ratios, flame temperatures, and flame radii ranges used for data analysis, and the results resolve some discrepancies seen in the literature for dimethyl ether flame speeds.     

Single-phase fluid flow distribution and heat transfer in microstructured reactors

Single-phase microreactors and micro-heat-exchangers have been widely used in industrial and scientific applications over the last decade. In several cases, operation of microreactors has shown that their expected efficiency cannot be reached either due to non-uniform distribution of reactants between different channels or due to flow maldistribution between individual microreactors working in parallel. The latter problem can result in substantial temperature deviations between different microreactors resulting in thermal runaway which could arise from an exothermic reaction. Thus advances in the understanding of heat transfer and fluid flow distribution continue to be crucial in achieving improved performance, efficiency and safety in microstructured reactors used for different applications. This paper presents a review of the experimental and numerical results on fluid flow distribution, heat transfer and combination thereof, available in the open literature. Heat transfer in microchannels can be suitably described by standard theory and correlations, but scaling effects (entrance effects, conjugate heat transfer, viscous heating, and temperature-dependent properties) have often to be accounted for in microsystems. Experiments with single channels are in good agreement with predictions from the published correlations. The accuracy of multichannel experiments is lower due to flow maldistribution. Special attention is devoted to theoretical and experimental studies on the effect of a flow maldistribution on the thermal and conversion response of catalytic microreactors. The review concludes with a set of design recommendations aimed at improving the reactor performance.     

Separation and recovery of the constituents from lignocellulosic biomass by using ionic liquids and acetic acid as co-solvents for mild hydrolysis

Previously, ionic liquids were found to partially dissolve lignocellulosic biomass. Here, it is reported that the biomass itself does not dissolve directly, but that it is hydrolyzed first before the constituents (cellulose, hemicellulose and lignin) dissolve into the ionic liquid. By addition of an acidic catalyst, this hydrolysis step can take place at milder conditions. Acetic acid is chosen as a suitable acidic catalyst, because it is already present in lignocellulosic biomass in the form of acetyl groups on the hemicellulose. Here, it is shown that acetic acid also works as co-solvent, increasing the solubility of the constituents of lignocellulosic biomass in the ionic liquid. The milder conditions for hydrolysis result in a higher degree of utilization of the lignocellulosic biomass, whereby all constituents can be fully recovered and further processed and the ionic liquid can be reused.     

Low temperature CO pulse adsorption for the determination of Pt particle size in a Pt/cerium-based oxide catalyst

Unexpectedly large amounts of CO adsorption have resulted from a pulse adsorption experiment at 323 K, giving about 300% Pt dispersion in a Pt/cerium-based oxide catalyst. An in situ diffuse reflectance infrared Fourier transform spectroscopic investigation on a Pt/cerium-based oxide during CO adsorption has revealed that carbonate species on the cerium oxide surface are responsible for the unrealistically large CO adsorption at 323 K, as a result of CO spillover. Lowering the temperature to 195 K considerably diminished the amount of CO adsorption. The size of the Pt particles in the Pt/cerium-based oxide catalyst was determined by CO pulse adsorption at 195 K and showed good agreement with the particle size determined by X-ray diffraction and low energy ion scattering. This indicates that CO pulse adsorption at 195 K is a useful technique to reliably estimate the Pt particle size in a Pt/cerium-based oxide catalyst.     

Maternal attitudes and child-feeding practices: relationship with the BMI of Chilean children

Background  

Chile has experienced the nutritional transition due to both social and economic progress. As a consequence, higher rates of overweight and obesity have been observed in children. In western countries, researchers have tried to determine pathways by which parents influence their children's eating behavior; up to now findings have been inconsistent. The objective of this study was to evaluate the cross-sectional and retrospective relationship between maternal attitudes and child-feeding practices and children's weight status in children who had been subject of an obesity prevention intervention for two years.     

Activation of serotonergic neurotransmission during the performance of aggressive behavior in rats.

High aggression is often linked to lowered serotonin (5-HT) neurotransmission. Although this may hold for high aggression as a trait characteristic of an individual, serotonergic activity is probably increased during performance of aggressive behavior. To test this hypothesis, first, the 5-HT1A agonist alnespirone and gamma aminobutyric acid-A agonist muscimol were administered into the dorsal raphe nucleus. These treatments which inhibit 5-HT neuronal activity, were shown to decrease performance of aggressive behavior. Second, after a resident-intruder test, the activation of 5-HT neurons (measured by c-fos expression) was increased in high-aggressive rats, compared with low-aggressive rats or control rats that were not subjected to a social confrontation. Results show that performance of aggressive behavior increases 5-HT neuronal activity and that preventing this activation inhibits expression of aggressive behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A Silent Antipode: The Making and Breaking of Psychoanalyst Wilhelm Stekel.

Wilhelm Stekel, one of Freud's earliest followers, was expelled from the psychoanalytic movement in 1912 ostensibly because he did not know how to behave himself. Although he remained active as a psychoanalyst, his post-1912 work was mostly neglected, and consequently his historic import is seriously undervalued. The author reviews recent literature, reexamines the Freud-Stekel break, and focuses on Stekel's role as silent antipode. Freud's reference to an unnamed individual in his 1907 Gradiva paper (S. Freud, 1907/1959b)-commonly believed to be Jung-is now identified as Stekel. This not-unimportant correction of the historical record begins the exploration of a hitherto-undocumented antagonistic dialogue between Stekel and Freud. (PsycINFO Database Record (c) 2010 APA, all rights reserved)