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Search Results: 1 - 10 of 414798 matches for " Fsadni Andrew M. "
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Micro bubble formation and bubble dissolution in domestic wet central heating systems
Fsadni Andrew M.,Ge Yunting
EPJ Web of Conferences , 2012, DOI: 10.1051/epjconf/20122501016
Abstract: 16 % of the carbon dioxide emissions in the UK are known to originate from wet domestic central heating systems. Contemporary systems make use of very efficient boilers known as condensing boilers that could result in efficiencies in the 90-100% range. However, research and development into the phenomenon of micro bubbles in such systems has been practically non-existent. In fact, such systems normally incorporate a passive deaerator that is installed as a ‘default’ feature with no real knowledge as to the micro bubble characteristics and their effect on such systems. High saturation ratios are known to occur due to the widespread use of untreated tap water in such systems and due to the inevitable leakage of air into the closed loop circulation system during the daily thermal cycling. The high temperatures at the boiler wall result in super saturation conditions which consequently lead to micro bubble nucleation and detachment, leading to bubbly two phase flow. Experiments have been done on a test rig incorporating a typical 19 kW domestic gas fired boiler to determine the expected saturation ratios and bubble production and dissolution rates in such systems.
The Impact of Microbiological Pollutants on School Indoor Air Quality  [PDF]
Peter Fsadni, Bezzina Frank, Claudia Fsadni, Stephen Montefort
Journal of Geoscience and Environment Protection (GEP) , 2017, DOI: 10.4236/gep.2017.55004
Abstract: Asthma is common in children with allergens and mould influencing the development of the disease. Since children spend most of their time outside their homes within the school environment, school indoor air quality can directly influence their respiratory health. This study aims to identify microbiological contaminants in Maltese schools. The association between contaminants, respiratory health and school characteristics has been analysed. Five primary schools were selected with 9 to 11 years old students participating. Standardised health questionnaires, lung function tests, and school characterisation were performed. Dust samples were analysed for fungi, bacteria and allergens were performed. Penicillium/Aspergillus/Paecilomyces/Variotii (PenAsp) group had the highest median indoor concentration followed by Mycobacterial and Streptomyces species. There was a significant negative correlation between PenAsp and Mycobacterium spp levels in all the participating schools (r = ?0.42; p = 0.03). Cat allergen in classroom dust correlated positively with the number of cat owners (r = 0.43; p = 0.041). High exposure to fungi, bacteria and allergens was significantly associated with upper and lower airway atopy. School/classroom characteristics and cleaning protocols were significantly associated with exposure to these pollutants. In conclusion, fungi, bacteria, endotoxin, cat and dog allergens have been found to have a direct influence on school indoor air quality in the Maltese Islands. A significant association was observed between these contaminants and upper and lower airway atopy. Specific school, classroom, cleaning and maintenance characteristics have been identified as having a direct impact on indoor air quality.
Two-phase distribution in the vertical flow line of a domestic wet central heating system
Fsadni A.-M.,Ge Y.T.
EPJ Web of Conferences , 2013, DOI: 10.1051/epjconf/20134501030
Abstract: The theoretical and experimental aspects of bubble distribution in bubbly two-phase flow are reviewed in the context of the micro bubbles present in a domestic gas fired wet central heating system. The latter systems are mostly operated through the circulation of heated standard tap water through a closed loop circuit which often results in water supersaturated with dissolved air. This leads to micro bubble nucleation at the primary heat exchanger wall, followed by detachment along the flow. Consequently, a bubbly two-phase flow characterises the flow line of such systems. The two-phase distribution across the vertical and horizontal pipes was measured through a consideration of the volumetric void fraction, quantified through photographic techniques. The bubble distribution in the vertical pipe in down flow conditions was measured to be quasi homogenous across the pipe section with a negligible reduction in the void fraction at close proximity to the pipe wall. Such a reduction was more evident at lower bulk fluid velocities.
Invasive Species Echinochloa colona Reduces Abundance and Diversity of Resident Plant Communities in Tropical Wetland  [PDF]
Samora M. Andrew
Open Journal of Ecology (OJE) , 2018, DOI: 10.4236/oje.2018.89029
Abstract:
Although the relationship between invasive alien species (IAS) and plant community structure has attracted considerable interest, the impacts of IAS on abundance and diversity of resident plant communities in species rich-ecosystems, such as tropical wetlands are poorly understood. Consequently, this has impeded development of improved management strategies and successful restoration of invaded tropical wetlands. Therefore, data on vegetation were collected from 60 plots of 20 × 50 m to study the impacts of alien invasive grass Echinochloa colona (L.) Link abundance on plant community abundance, richness, evenness and diversity of resident plant species within grasslands of the Kilombero Valley wetland, Tanzania. Moreover, the impacts of abundance of E. colona on plant functional groups (i.e. graminoids, forbs and shrubs) richness were also explored. Generalized linear models showed that community richness, evenness, diversity and abundance of resident species were negatively related to the E. colona abundance. There was a negative relationship between richness of graminoids and shrubs and the abundance of E. colona. Similarly, the abundance of graminoids, forbs and shrubs is related negatively to the abundance of E. colona. Given that most of the community and functional group attributes of resident plants is related negatively to E.
On the Consistency of a Firm’s Value with a Lognormal Diffusion Process  [PDF]
Andrew M. K. Cheung, Van Son Lai
Journal of Mathematical Finance (JMF) , 2012, DOI: 10.4236/jmf.2012.21003
Abstract: A partial equilibrium model is developed to examine conditions supporting the representation of the value of a firm by the lognormal diffusion process. The model formalizes the operating side of the firm and leads to a formula valuing the firm’s risky profit stream. The present value formula is then compared to the existing work on valuing exogenous risky income stream. Implications of the resulted pricing model on the volatility of the firm value processes are explored.
Emotions and Emotion Regulation in a Female Couple Undergoing in Vitro Fertilization Treatment  [PDF]
Tracey J. Devonport, Andrew M. Lane
Psychology (PSYCH) , 2013, DOI: 10.4236/psych.2013.46A1004
Abstract:

Research indicates that women undergoing In Vitro Fertilization (IVF) experience intense unwanted emotions, and that these emotions may result in the decision to abandon treatment. This case-study explored stressors, emotional responses and emotion regulation strategies of a female couple undergoing IVF procedures over a ten-week period. A mixed-method approach involved participants completing a daily open-ended diary and self-report scales to assess emotions and emotion regulation in relation to partner and self. Diary results indicated both partners experienced frequent stressors resulting from the IVF process, stressors that were intensified by perceptual and financial factors. Participants experienced a range of intense pleasant (e.g., happy, excited) and unpleasant emotions (e.g., depressed, anxious), and sought to down-regulate unpleasant emotions using a range of cognitive, behavioral, and social strategies. Questionnaire data indicated complementary styles of emotion regulation that appeared to help sustain pleasant emotions and down-regulate unpleasant emotions. Future research should test the effectiveness of interventions to help manage unwanted emotional responses to IVF treatment and corresponding regulatory efforts.

Bird species composition and diversity in habitats with different disturbance histories at Kilombero Wetland, Tanzania  [PDF]
Wilbard A. Ntongani, Samora M. Andrew
Open Journal of Ecology (OJE) , 2013, DOI: 10.4236/oje.2013.37056
Abstract:

Wetland natural grasslands are important habitats for avian populations throughout the world. Unfortunately the increase of human population and rise in demand for settlements and agricultural land have degraded these habitats in many tropical wetlands. To effectively restore these natural grasslands and conserve avifaunal biodiversity, understanding of the relationships between habitat conditions and bird community structure are central. We used a combination of information from nearby villagers and field surveys to establish two important grassland habitats with low and high disturbance histories, and related the habitats to bird community structure. We surveyed a total of 119 sites in the two habitats to examine variation in the abundance, richness, diversity and composition of birds at Kilombero Wetland Tanzania. In total, 3049 individuals, 126 species, 88 genera and 45 families were recorded from Kilombero grasslands. Our results show that grasslands with low human disturbance had more number of bird species, genera, families and diversity (both ShannonWiener and Simpson) than the most disturbed grasslands atp< 0.05. However, the abundance and Shannon evenness of birds were not different (p> 0.05) between low and highly disturbed grassland habitats suggesting that other factors including variety of foraging sites are important. This study confirms that the wetland grasslands of Kilombero are important for conservation of birds including rare and endemic species. It is recommended that anthropogenic disturbancesshould be minimized including control of fire, regulation of agricultural activities and population of cattle within the wetland system to restore and conserve biodiversity.


Tidal Heights in Hyper-Synchronous Estuaries  [PDF]
Ian M. Kidd, Shuhong Chai, Andrew Fischer
Natural Resources (NR) , 2014, DOI: 10.4236/nr.2014.511053
Abstract:
Inconsistencies between datasets are examined with reference to flood tidal elevations in the Tamar River estuary, Tasmania Australia. Errors in a 30-year-old commonly cited dataset have been perpetuated in subsequent publications and datasets, and a clarification is herein provided. Elevation of the flood tidal wave as it propagates the estuary is evident in mean tide level and mean sea level, although the analysis is compromised by the temporal differences of the datasets. As sea levels rise due to global warming, the importance of accurate on-going sea level data in any estuary will become more acute.
Using Single-Item Measures to Examine the Relationships between Work, Personality, and Well-Being in the Workplace  [PDF]
Gary M. Williams, Andrew P. Smith
Psychology (PSYCH) , 2016, DOI: 10.4236/psych.2016.76078
Abstract:

Measuring the well-being of employees through questionnaire measures can give a useful indication of the positive or negative mental health of a workforce along with their satisfaction with their circumstances. Furthermore, measuring the antecedents of these outcomes provides a basis for reducing negative outcomes and promoting positive mental health and satisfaction within an organization. This endeavour can quickly become impractical, however, as taking into account the range of possible environmental or personal factors, can lead to a lengthy and burdensome measurement tool. The current paper examines the use of single-items for this purpose, demonstrating that single-item measures of work-related and personality factors exhibit relationships with each other and with outcomes that the literature on well-being predicts. Using multiple-regression analysis, the results show that work related factors such as control and reward provide significant predictors of well-being outcomes including job satisfaction, while personality factors such as self-esteem and self-efficacy are significant predictors of all outcome measures. Furthermore, variations in the relationships with specific outcomes and interaction effects are found. The results suggest that using single-item measures may provide a valid approach to investigating well-being in the workplace in circumstances that may require very brief scales.

Estimating a Falsified Model  [PDF]
Andrew J. Buck, George M. Lady
Advances in Pure Mathematics (APM) , 2016, DOI: 10.4236/apm.2016.68040
Abstract: It is common econometric practice to propose a system of equations, termed the “structure,” estimate each endogenous variable in the structure via a linear regression with all of the exogenous variables as arguments, and then employ one of variety of regression techniques to recapture the coefficients in the (Jacobian) arrays of the structure. A recent literature, e.g., [1], has shown that a qualitative analysis of a model’s structural and estimated reduced form arrays can provide a robust procedure for assessing if a model’s hypothesized structure has been falsified. This paper shows that the even weaker statement of the model’s structure provided by zero restrictions on the structural arrays can be falsified, independent of the proposed nonzero entries. When this takes place, multi-stage least squares, or any procedure for estimating the structural arrays with the zero restrictions imposed, will present estimates that could not possibly have generated the data upon which the estimated reduced form is based. The examples given in the paper are based upon a Monte Carlo sampling procedure.
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