Performance calculations of residential cooling systems for simplified energy analysis

The seasonal performance of space cooling systems generally depends on indoor and outdoor temperatures and humidities and on the ratio between actual cooling loads and cooling equipment size. In principle, any given weather condition and desired indoor dry-bulb temperature calls for an interactive application of psychrometrics and equipment performance curves until satisfactory indoor conditions are derived for which both sensible and latent cooling loads equal sensible and latent heat removal rates. This paper presents a simplified approach that derives the indoor wet-bulb temperature in close form for both cases when the cooling system condenses water from the space and when it does not. This approach relies on a local linearization of the psychrometric chart in the region of interest for indoor comfort conditions. Performance curves for total and sensible capacity and for the electric power input were derived for several different residential air-to-air reciprocating compressive cooling systems. The performance curves are empirical fits to manufacturer's data or to laboratory results. The predictions of the simplified method were compared with DOE-2 when calculating space cooling consumption for a residence in both a hot arid and in a hot humid climate. The comparison showed excellent agreement both for hour-by-hour calculations and for monthly calculation of this method are sufficiently simple to be applicable to micro-computers and pocket calculators.     

Distinct Expression Patterns of Cxcl12 in Mesenchymal Stem Cell Niches of Intact and Injured Rodent Teeth

Specific stem cell populations within dental mesenchymal tissues guarantee tooth homeostasis and regeneration throughout life. The decision between renewal and differentiation of stem cells is greatly influenced by interactions with stromal cells and extracellular matrix molecules that form the tissue specific stem cell niches. The Cxcl12 chemokine is a general marker of stromal cells and plays fundamental roles in the maintenance, mobilization and migration of stem cells. The aim of this study was to exploit Cxcl12-GFP transgenic mice to study the expression patterns of Cxcl12 in putative dental niches of intact and injured teeth. We showed that endothelial and stromal cells expressed Cxcl12 in the dental pulp tissue of both intact molars and incisors. Isolated non-endothelial Cxcl12⁺ dental pulp cells cultured in different conditions in vitro exhibited expression of both adipogenic and osteogenic markers, thus suggesting that these cells possess multipotent fates. Taken together, our results show that Cxcl12 is widely expressed in intact and injured teeth and highlight its importance as a key component of the various dental mesenchymal stem cell niches.     

A methodological approach to fully automated highly accelerated life tests

Microsystem Technologies - Highly accelerated life test (HALT) is a test methodology to evaluate reliability of mechanical and electromechanical devices. HALT is often used on devices that must be...     

A genetic algorithm for the Flexible Job-shop Scheduling Problem

In this paper, we present a genetic algorithm for the Flexible Job-shop Scheduling Problem (FJSP). The algorithm integrates different strategies for generating the initial population, selecting the individuals for reproduction and reproducing new individuals. Computational result shows that the integration of more strategies in a genetic framework leads to better results, with respect to other genetic algorithms. Moreover, results are quite comparable to those obtained by the best-known algorithm, based on tabu search. These two results, together with the flexibility of genetic paradigm, prove that genetic algorithms are effective for solving FJSP.     

Fibre Bragg grating location and spatial period determination in DBR lasers by side-scatter detection of pump radiation

A simple technique for locating the position of Bragg grating reflectors in erbium-doped fibre lasers is proposed. The technique consists of the side detection of the pump radiation scattered from the grating. It is also possible to obtain the spatial period of the grating by measuring the diffraction angle, which closely depends on this parameter. This technique can also be applied to passive fibre Bragg gratings.     

A dynamic reanalysis technique for general structural modifications under deterministic or stochastic input

A procedure for the dynamic reanalysis of linear systems subjected to deterministic or stochastic loads is presented. The procedure allows to evaluate the dynamic response of the modified structural system starting from the knowledge of the transition matrix and the eigenvectors of the original system. The case in which topological modifications are introduced can be successfully treated. The method relays on an unconditionally stable step-by-step procedure based on the “dynamic modification method”. As shown in the numerical applications, the technique is computationally effective and leads to accurate results for a broad class of structural modifications.     

Detection of minimal but significant amount of von Willebrand factor in human omentum mesothelial cell cultures

The presence of von Willebrand factor (vWF) in human mesothelial cells is a controversial issue. The aim of this paper was to investigate the presence of vWF in human mesothelial cell cultures by means of multiple specific techniques and to compare the amount of vWF to that in endothelial cell cultures. Morphological evidence that vWF is present in the cell cytoplasm in human omentum mesothelial cells (HOMC) has been obtained by vWF staining by means of anti-vWF antibodies and immunofluorescence. The vWF concentration value (measured by ELISA) was 0.02 ng/mL in the supernatant of HOMC (160,000 ng/mL cells/mL after 12-48 hours) and between 0.08-0.12 ng/mL in the supernatant of endothelial cell cultures (160,000 cells/mL). Ethidium-bromide staining of PCR products recorded the typical vWF signal both in the endothelial and in the mesothelial cell cultures, although it was noticeably more intense in the endothelial cell culture. These data show that minimal but significant amounts of vWF are present in human mesothelial cell cultures.