395 resultados para Stable Distribution


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Carbon fibre reinforced polymer (CFRP) sheets have many outstanding properties such as high strength, high elastic modulus, light weight and good durability which are made them a suitable alternative for steel in strengthening work. This paper describe the ultimate load carrying capacity of steel hollow sections at effective bond length in terms of its cross sectional area and the stress distribution within bond region for different layers CFRP. It was found that depending on their size and orientation of uni- directional CFRP layers, the ultimate tensile load was different. Along with these tests, non linear finite element analysis was also performed to validate the ultimate load carrying capacity depending on their cross sections. The predicted ultimate loads from FE analysis are found very close to the laboratory test results. The validated model has been used to determine the stress distribution at bond joint for different orientation of CFRP. This research shows the effect of stress distribution and suitable wrapping layer to be used for the strengthening of steel hollow sections in tension.

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It is commonly assumed that rates of accumulation of organic-rich strata have varied through geologic time with some periods that were particularly favorable for accumulation of petroleum source rocks or coals. A rigorous analysis of the validity of such an assumption requires consideration of the basic fact that although sedimentary rocks have been lost through geologic time to erosion and metamorphism. Consequently, their present-day global abundance decreases with their geologic age. Measurements of the global abundance of coal-bearing strata suggest that conditions for coal accumulation were exceptionally favorable during the late Carboniferous. Strata of this age constitute 21% of the world's coal-bearing strata. Global rates of coal accumulation appear to have been relatively constant since the end of the Carboniferous, with the exception of the Triassic which contains only 1.75% of the world's coal-bearing strata. Estimation of the global amount of discovered oil by age of the source rock show that 58% of the world's oil has been sourced from Cretaceous or younger strata and 99% from Silurian or younger strata. Although most geologic periods were favourable for oil source-rock accumulation the mid-Permian to mid-Jurassic appears to have been particularly unfavourable accounting for less than 2% of the world's oil. Estimation of the global amount of discovered natural gas by age of the source rock show that 48% of the world's oil has been sourced from Cretaceous or younger strata and 99% from Silurian or younger strata. The Silurian and Late Carboniferous were particularly favourable for gas source-rock accumulation respectively accounting for 12.9% and 6.9% of the world's gas. By contrast, Permian and Triassic source rocks account for only 1.7% of the world's natural gas. Rather than invoking global climatic or oceanic events to explain the relative abundance of organic rich sediments through time, examination of the data suggests the more critical control is tectonic. The majority of coals are associated with foreland basins and the majority of oil-prone source rocks are associated with rifting. The relative abundance of these types of basin through time determines the abundance and location of coals and petroleum source rocks.

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This paper describes an analysis of construction project bids to determine (a) the global distribution and (b) factors influencing the distribution of bids. The global distribution of bids was found, by using a battery of ll test statistics, to be approximated by a three-parameter log normal distribution. No global spread parameter was found. A multivariate analysis revealed the year of tender to be the major influencing factor. Consideration of the construction order, tender price and output indices lead to the conclusion that distributional spread reflected the degree of difference in pricing policies between bidders and the skewness of the distributions reflected the degree of competition. The paper concludes with a tentative model of the causal relationships between the factors and distributional characteristics involved.

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The Schizosaccharomyces pombe Mei2 gene encodes an RNA recognition motif (RRM) protein that stimulates meiosis upon binding a specific non-coding RNA and subsequent accumulation in a “mei2-dot” in the nucleus. We present here the first systematic characterization of the family of proteins with characteristic Mei2-like amino acid sequences. Mei2-like proteins are an ancient eukaryotic protein family with three identifiable RRMs. The C-terminal RRM (RRM3) is unique to Mei2-like proteins and is the most highly conserved of the three RRMs. RRM3 also contains conserved sequence elements at its C-terminus not found in other RRM domains. Single copy Mei2-like genes are present in some fungi, in alveolates such as Paramecium and in the early branching eukaryote Entamoeba histolytica, while plants contain small families of Mei2-like genes. While the C-terminal RRM is highly conserved between plants and fungi, indicating conservation of molecular mechanisms, plant Mei2-like genes have changed biological context to regulate various aspects of developmental pattern formation.

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Ancient sandstones include important reservoirs for hydrocarbons (oil and gas), but, in many cases, their ability to serve as reservoirs is heavily constrained by the effects of carbonate cements on porosity and permeability. This study investigated the controls on distribution and abundance of carbonate cements within the Jurassic Plover Formation, Browse Basin, North West Shelf, Australia. Samples were analysed petrographically with point counting of 59 thin sections and mineralogically with x-ray diffraction from two wells within the Torosa Gas Field. Selected samples were also analysed for stable isotopes of O and C. Sandstones are classified into eleven groups. Most abundant are quartzarenites and then calcareous quartzarenites. Lithology ranged between sandstones consisting of mostly quartz with scant or no carbonate in the form of cement or allochems, to sandstones with as much as 40% carbonate. The major sources of carbonate cement in Torosa 1 and Torosa 4 sandstones were found to be early, shallow marine diagenetic processes (including cementation), followed by calcite cementation and recrystallisation of cements and allochems during redistribution by meteoric waters. Blocky and sparry calcite cements, indicative of meteoric environments on the basis of stable isotope values and palaeotemperature assessment, overprinted the initial shallow marine cement phase in all cases and meteoric cements are dominant. Torosa 4 was influenced more by marine settings than Torosa 1, and thus has the greater potential for calcite cement. The relatively low compaction of calcite-cemented sandstones and the stable isotope data suggest deep burial cementation was not a major factor. Insufficient volcanic rock fragments or authigenic clay content infers alteration of feldspars was not a major source of calcite. Very little feldspar is present, altered or otherwise. Hence, increased alkalinity from feldspar dissolution is not a contributing factor in cement formation. Increased alkalinity from bacterial sulphate reduction in organic–rich fine sediments may have driven limited cementation in some samples. The main definable and significant source of diagenetic marine calcite cement originated from original marine cements and the nearby dissolution of biogenic sources (allochems) at relatively shallow depths. Later diagenetic fluids emplaced minor dolomite, but this cement did not greatly affect the reservoir quality in the samples studied.

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In this paper we report a new neutron Compton scattering (NCS) measurement of the ground state single atom kinetic energy of polycrystalline beryllium at momentum transfers in the range 27}104 As ~1 and temperatures in the range 110}1150 K. The measurements have been made with the electron Volt spectrometer (eVS) at the ISIS facility and the measured kinetic energies are shown to be &10% higher than calculations made in the harmonic approximation.

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Dehydration of food materials requires water removal from it. This removal of moisture prevents the growth and reproduction of microorganisms that cause decay and minimizes many of the moisture-driven deterioration reactions (Brennan, 1994). However, during food drying, many other changes occur simultaneously resulting in a modified overall quality (Kompany et al., 1993). Among the physical attributes of dried food material porosity and microstructure are the important ones that can dominant other quality of dried foods (Aguilera et al., 2000). In addition, this two concerned quality attributes affected by process conditions, material components and raw structure of food stuff. In this work, temperature moisture distribution within food materials during microwave drying will be taken into consideration to observe its participation on the microstructure and porosity of the finished product. Apple is the selective materials for this work. Generally, most of the food materials are found in non-uniformed moisture contained condition. To develop non uniform temperature distribution, food materials have been dried in a microwave oven with different power levels (Chua et al., 2000). First of all, temperature and moisture model is simulated by COMSOL Multiphysics. Later on, digital imaging camera and Image Pro Premier software have been deployed to observation moisture distribution and thermal imaging camera for temperature distribution. Finally, Microstructure and porosity of the food materials are obtained from scanning electron microscope and porosity measuring devices respectively . Moisture distribution and temperature during drying influence the microstructure and porosity significantly. Specially, High temperature and moisture contained regions show less porosity and more rupture. These findings support other literatures of Halder et al. (2011) and Rahman et al (1990). On the other hand, low temperature and moisture regions depict uniform microstructure and high porosity. This work therefore assists in better understanding of the role of moisture and temperature distribution to a prediction of micro structure and porosity of dried food materials.

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Like music and the news media before it, the film and television business is now facing its time of digital disruption. Major changes are being brought about in global online distribution of film and television by new players, such as Google/YouTube, Apple, Amazon, Yahoo!, Facebook, Netflix and Hulu, some of whom massively outrank in size and growth the companies that run film and television today. Content, Hollywood has always asserted, is King. But the power and profitability in screen industries have always resided in distribution. Incumbents in the screen industries tried to control the emerging dynamics of online distribution, but failed. The new, born digital, globally focused, players are developing TV network-like strategies, including commissioning content that has widened the net of what counts as television. Content may be King, but these new players may become the King Kongs of the online world.

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This paper proposes a distributed control approach to coordinate multiple energy storage units (ESUs) to avoid violation of voltage and thermal constraints, which are some of the main power quality challenges for future distribution networks. ESUs usually are connected to a network through voltage source converters. In this paper, both ESU converters active and reactive power are used to deal with the above mentioned power quality issues. ESUs' reactive power is proposed to be used for voltage support, while the active power is to be utilized in managing network loading. Two typical distribution networks are used to apply the proposed method, and the simulated results are illustrated in this paper to show the effectiveness of this approach.

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As a good solution to the shortage and environmental unfriendliness of fossil fuels, plug-in electric vehicles (PEVs) attract much interests of the public. To investigate the problems caused by the integration of numerous PEVs, a lot of research work has been done on the grid impacts of PEVs in aspects including thermal loading, voltage regulation, transformer loss of life, unbalance, losses, and harmonic distortion levels. This paper surveys the-state-of-the-art of the research in this area and outline three possible measures for a power grid company to make full use of PEVs.

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OBJECTIVE: The objective of this study was to describe the distribution of conjunctival ultraviolet autofluorescence (UVAF) in an adult population. METHODS: We conducted a cross-sectional, population-based study in the genetic isolate of Norfolk Island, South Pacific Ocean. In all, 641 people, aged 15 to 89 years, were recruited. UVAF and standard (control) photographs were taken of the nasal and temporal interpalpebral regions bilaterally. Differences between the groups for non-normally distributed continuous variables were assessed using the Wilcoxon-Mann-Whitney ranksum test. Trends across categories were assessed using Cuzick's non-parametric test for trend or Kendall's rank correlation τ. RESULTS: Conjunctival UVAF is a non-parametric trait with a positively skewed distribution. Median amount of conjunctival UVAF per person (sum of four measurements; right nasal/temporal and left nasal/temporal) was 28.2 mm(2) (interquartile range 14.5-48.2). There was an inverse, linear relationship between UVAF and advancing age (P<0.001). Males had a higher sum of UVAF compared with females (34.4 mm(2) vs 23.2 mm(2), P<0.0001). There were no statistically significant differences in area of UVAF between right and left eyes or between nasal and temporal regions. CONCLUSION: We have provided the first quantifiable estimates of conjunctival UVAF in an adult population. Further data are required to provide information about the natural history of UVAF and to characterise other potential disease associations with UVAF. UVR protective strategies should be emphasised at an early age to prevent the long-term adverse effects on health associated with excess UVR.

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Aim: To describe the recruitment, ophthalmic examination methods and distribution of ocular biometry of participants in the Norfolk Island Eye Study, who were individuals descended from the English Bounty mutineers and their Polynesian wives. Methods: All 1,275 permanent residents of Norfolk Island aged over 15 years were invited to participate, including 602 individuals involved in a 2001 cardiovascular disease study. Participants completed a detailed questionnaire and underwent a comprehensive eye assessment including stereo disc and retinal photography, ocular coherence topography and conjunctival autofluorescence assessment. Additionally, blood or saliva was taken for DNA testing. Results: 781 participants aged over 15 years were seen (54% female), comprising 61% of the permanent Island population. 343 people (43.9%) could trace their family history to the Pitcairn Islanders (Norfolk Island Pitcairn Pedigree). Mean anterior chamber depth was 3.32mm, mean axial length (AL) was 23.5mm, and mean central corneal thickness was 546 microns. There were no statistically significant differences in these characteristics between persons with and without Pitcairn Island ancestry. Mean intra-ocular pressure was lower in people with Pitcairn Island ancestry: 15.89mmHg compared to those without Pitcairn Island ancestry 16.49mmHg (P = .007). The mean keratometry value was lower in people with Pitcairn Island ancestry (43.22 vs. 43.52, P = .007). The corneas were flatter in people of Pitcairn ancestry but there was no corresponding difference in AL or refraction. Conclusion: Our study population is highly representative of the permanent population of Norfolk Island. Ocular biometry was similar to that of other white populations. Heritability estimates, linkage analysis and genome-wide studies will further elucidate the genetic determinants of chronic ocular diseases in this genetic isolate.

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A nanoparticles size is one of their key physical characteristics that can affect their fate in a human’s respiratory tract (in case of inhalation) and also in the environment. Hence, measuring the size distribution of nanoparticles is absolutely essential and contributes greatly to their characterization. For years, Scanning Mobility Particle Sizers (SMPS), which rely on measuring the electrical mobility diameter of particles, have been used as one of the most reliable real-time instruments for the size distribution measurement of nanoparticles. Despite its benefits, this instrument has some drawbacks, including equivalency problems for non-spherical particles (i.e. assuming a non-spherical particle is equal to a spherical particle of diameter d due to the same electrical mobility), as well as limitations in terms of its use in workplaces, because of its large size and the complexity of its operation...

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In this report, a detailed FTIR fitting analysis was used to recognize Mg, Zn and Al homogeneous distribution in MgxZnyAl(x+y)/2-Layered double hydroxide (LDH) hydroxyl layer. In detail, OH-Mg2Al:OH-Mg3 ratios decreased from 95.2:4.8 (MIR) and 94.2:5.8 (NIR) to 58.9:41.1 (MIR) and 61.8:38.2 (NIR), when Mg:Al increased from 2.2:1.0 to 4.1:1.0 in MgAl-LDHs. These fitting results were similar with theoretical calculations of 94.3:5.7 and 59.0:41.0. In a further analysis of MgxZnyAl(x+y)/2-LDHs, OH bonded Zn2Mg, Zn2Al, MgZnAl, Mg2Al and Mg2Zn peaks were identified at 3420, 3430, 3445–3450, 3454 and 3545 cm-1, respectively. With the decrease of Mg:Zn from 3:1 to 1:3, metal-hydroxyl bands changed from OH-Mg2Al and MgZnAl (with a ratio of 49.4:50.6) to OH-MgZnAl and Zn2Al (with a ratio of 55.0:45.0). They were also similar with theoretical calculations of 47.6:52.4 and 54.6:45.4. As a result, these results show that there is an ordered cation distribution in MgxZnyAl(x+y)/2-LDH, and FTIR is feasible in recognizing this structure.

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During food drying, many other changes occur simultaneously, resulting in an improved overall quality. Among the quality attributes, the structure and its corresponding color influence directly or indirectly other properties of food. In addition, these quality attributes are affected by process conditions, material components and the raw structure of the foodstuff. In this work, the temperature distribution within food materials during microwave drying has been taken into consideration to observe its role in color modification. In order to determine the temperature distribution of microwave-dried food (apple), a thermal imaging camera has been used. The image acquired from the digital camera has been analysed using image J software in order to get the color change of fresh and dried apple. The results show that temperature distribution plays an important role in determining the quality of the food. The thermal imaging camera was deployed to observe the temperature distribution within food materials during drying. It is clearly observed from the higher value of (ERGB =102) and the uneven color change that uneven temperature distribution can influence customer perceptions of the quality of dried food. Simulation of a mathematical model of temperature distribution during microwave drying can make it possible to predict the colour and texture of the microwaved food.