899 resultados para Economies of density


Relevância:

90.00% 90.00%

Publicador:

Resumo:

The thesis is divided into four chapters. They are: introduction, experimental, results and discussion about the free ligands and results and discussion about the complexes. The First Chapter, the introductory chapter, is a general introduction to the study of solid state reactions. The Second Chapter is devoted to the materials and experimental methods that have been used for carrying out tile experiments. TIle Third Chapter is concerned with the characterisations of free ligands (Picolinic acid, nicotinic acid, and isonicotinic acid) by using elemental analysis, IR spectra, X-ray diffraction, and mass spectra. Additionally, the thermal behaviour of free ligands in air has been studied by means of thermogravimetry (TG), derivative thermogravimetry (DTG), and differential scanning calorimetry (DSC) measurements. The behaviour of thermal decomposition of the three free ligands was not identical Finally, a computer program has been used for kinetic evaluation of non-isothermal differential scanning calorimetry data according to a composite and single heating rate methods in comparison with the methods due to Ozawa and Kissinger methods. The most probable reaction mechanism for the free ligands was the Avrami-Erofeev equation (A) that described the solid-state nucleation-growth mechanism. The activation parameters of the decomposition reaction for free ligands were calculated and the results of different methods of data analysis were compared and discussed. The Fourth Chapter, the final chapter, deals with the preparation of cobalt, nickel, and copper with mono-pyridine carboxylic acids in aqueous solution. The prepared complexes have been characterised by analyses, IR spectra, X-ray diffraction, magnetic moments, and electronic spectra. The stoichiometry of these compounds was ML2x(H20), (where M = metal ion, L = organic ligand and x = water molecule). The environments of cobalt, nickel, and copper nicotinates and the environments of cobalt and nickel picolinates were octahedral, whereas the environment of copper picolinate [Cu(PA)2] was tetragonal. However, the environments of cobalt, nickel, and copper isonicotinates were polymeric octahedral structures. The morphological changes that occurred throughout the decomposition were followed by SEM observation. TG, DTG, and DSC measurements have studied the thermal behaviour of the prepared complexes in air. During the degradation processes of the hydrated complexes, the crystallisation water molecules were lost in one or two steps. This was also followed by loss of organic ligands and the metal oxides remained. Comparison between the DTG temperatures of the first and second steps of the dehydration suggested that the water of crystallisation was more strongly bonded with anion in Ni(II) complexes than in the complexes of Co(II) and Cu(II). The intermediate products of decomposition were not identified. The most probable reaction mechanism for the prepared complexes was also Avrami-Erofeev equation (A) characteristic of solid-state nucleation-growth mechanism. The tempemture dependence of conductivity using direct current was determined for cobalt, nickel, Cl.nd copper isonicotinates. An activation energy (ΔΕ), the activation energy (ΔΕ ) were calculated.The ternperature and frequency dependence of conductivity, the frequency dependence of dielectric constant, and the dielectric loss for nickel isonicotinate were determined by using altemating current. The value of s paralneter and the value of'density of state [N(Ef)] were calculated. Keyword Thermal decomposition, kinetic, electrical conduclion, pyridine rnono~ carboxylic acid, cOlnplex, transition metal compJex.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Studies suggest that frontotemporal lobar degeneration with transactive response (TAR) DNA-binding protein of 43kDa (TDP-43) proteinopathy (FTLD-TDP) is heterogeneous with division into four or five subtypes. To determine the degree of heterogeneity and the validity of the subtypes, we studied neuropathological variation within the frontal and temporal lobes of 94 cases of FTLD-TDP using quantitative estimates of density and principal components analysis (PCA). A PCA based on the density of TDP-43 immunoreactive neuronal cytoplasmic inclusions (NCI), oligodendroglial inclusions (GI), neuronal intranuclear inclusions (NII), and dystrophic neurites (DN), surviving neurons, enlarged neurons (EN), and vacuolation suggested that cases were not segregated into distinct subtypes. Variation in the density of the vacuoles was the greatest source of variation between cases. A PCA based on TDP-43 pathology alone suggested that cases of FTLD-TDP with progranulin (GRN) mutation segregated to some degree. The pathological phenotype of all four subtypes overlapped but subtypes 1 and 4 were the most distinctive. Cases with coexisting motor neuron disease (MND) or hippocampal sclerosis (HS) also appeared to segregate to some extent. We suggest: 1) pathological variation in FTLD-TDP is best described as a ‘continuum’ without clearly distinct subtypes, 2) vacuolation was the single greatest source of variation and reflects the ‘stage’ of the disease, and 3) within the FTLD-TDP ‘continuum’ cases with GRN mutation and with coexisting MND or HS may have a more distinctive pathology.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

This thesis describes the development of a complete data visualisation system for large tabular databases, such as those commonly found in a business environment. A state-of-the-art 'cyberspace cell' data visualisation technique was investigated and a powerful visualisation system using it was implemented. Although allowing databases to be explored and conclusions drawn, it had several drawbacks, the majority of which were due to the three-dimensional nature of the visualisation. A novel two-dimensional generic visualisation system, known as MADEN, was then developed and implemented, based upon a 2-D matrix of 'density plots'. MADEN allows an entire high-dimensional database to be visualised in one window, while permitting close analysis in 'enlargement' windows. Selections of records can be made and examined, and dependencies between fields can be investigated in detail. MADEN was used as a tool for investigating and assessing many data processing algorithms, firstly data-reducing (clustering) methods, then dimensionality-reducing techniques. These included a new 'directed' form of principal components analysis, several novel applications of artificial neural networks, and discriminant analysis techniques which illustrated how groups within a database can be separated. To illustrate the power of the system, MADEN was used to explore customer databases from two financial institutions, resulting in a number of discoveries which would be of interest to a marketing manager. Finally, the database of results from the 1992 UK Research Assessment Exercise was analysed. Using MADEN allowed both universities and disciplines to be graphically compared, and supplied some startling revelations, including empirical evidence of the 'Oxbridge factor'.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

In weak argillaceous rocks the unweathered strength may be barely sufficient to meet civil engineering reguirements and any reductjon due to weathering will be critical. This study investigates the weathering of the Lower Lias clays with particular reference to their petrography and engineering properties. Investigations revealed the Midland Basin of deposition to contain reasonable thicknesses of clay, relatively uniform in nature with a well developed weathered zone, From the available exposures, the weathering zone of the Blockley Clay pit was selected and sampled for laboratory investigations of; Structure, Mineralogy and Chemistry and Engineering Properties. The nature and orientation of the fissures in the unweathered clay were analysed. A close relationship was found to exist between the major joint set and the ground surface, with stress release due to excavation being almost negligible. Thin sections of the clay, examined for structural data, suggested that there exist layers or areas that have been disturbed as a result of density differences. Shear planes were found in both the unweathered and weathered clay, in the latter case often associated with remoulding of the material. A direct measure of remoulding was obtained from the birefringence ratio. The fabric was examined in closer detail using the scanning electron microscope. Mineralogy, as revealed by X-ray and optical techniques indicated illite as the dominant clay mineral, with kaolinite subsidiary; quartz, calcite, pyrite, chlorite/vermiculite are present as accessory minerals. Weathering changes this relationship, calcite and pyrite being removed early in the process, with illite being degraded. The cementing action of calcite and iron oxides was investigated however, this was shown to be negligible. Quantitative measurements of both fixed (with minerals) and free (oxide coatings) iron were obtained by atomic absorption, with the Fe 3+/ Fe2+ ratio obtained by Mossbauer spectroscopy, Evidence indicates that free iron oxide coatings only become important as a result of weathering with the maximum concentration in the very highly weathered material. Engineering index properties and shear strength values were taken throughout the profile, Relationships between moisture content and strength, liquid limit and iron (Fe) were obtained and a correlation between the weathering zomes and the shear strength/depth curve has been established.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

This study concerns the properties of the concentrated bittern solutions occurring as by-product from solar salt works, in relation to their potential use as liquid desiccants in cooling systems. Solutions of compositions similar to those of bitterns have been made up in the laboratory, as have concentrated mixtures of MgCl2–MgSO4–H2O. Measurements of vapour pressure have been carried out using an isoteniscope and are reported together with measurements of density and viscosity. Several theoretical models representing these properties are reviewed and compared against the experimental results; the average agreement between theory and experiment is within 5% for vapour pressure and better for the preferred models of the other two properties. Based on these findings, an expression is provided for the equilibrium relative humidity of bitterns as a function of concentration relative to raw seawater. The vapour pressures of bittern solutions are found to be similar to those of solutions containing only magnesium chloride but having the same mass fraction of total salts. Therefore magnesium chloride solution is a reasonable model for bitterns for the purpose of developing the proposed cooling system.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

This article examines cost economies, productivity growth and cost efficiency of the Chinese banks using a unique panel dataset that identifies banks' four outputs and four input prices over the period of 1995-2001. By assessing the appropriateness of model specification, and making use of alternative methodologies in evaluating the performance of banks, we find that the joint-stock commercial banks outperform state-owned commercial banks in productivity growth and cost efficiency. Under the variable cost assumption, Chinese banks display economies of scale, with state-owned commercial banks enjoying cost advantages over the joint-stock commercial banks. Consequently, our results highlight the ownership advantage of these two types of banks and generally support the ongoing banking reform and transformation that is currently taking place in China.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

This paper investigates vertical economies between generation and distribution of electric power, and horizontal economies between different types of power generation in the U.S. electric utility industry. Our quadratic cost function model includes three generation output measures (hydro, nuclear and fossil fuels), which allows us to analyze the effect that generation mix has on vertical economies. Our results provide (sample mean) estimates of vertical economies of 8.1% and horizontal economies of 5.4%. An extensive sensitivity analysis is used to show how the scope measures vary across alternative model specifications and firm types. © 2012 Blackwell Publishing Ltd and the Editorial Board of The Journal of Industrial Economics.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Copper(II) complexes of hexadentate ethylenediaminetetracarboxylic acid type ligands Heda3p and Heddadp (Heda3p = ethylenediamine-N-acetic-N,N',N'-tri-3-propionic acid; H eddadp = ethylenediamine-N,N'-diacetic-N,N'-di-3- propionic acid) have been prepared. An octahedral trans(O) geometry (two propionate ligands coordinated in axial positions) has been established crystallographically for the Ba[Cu(eda3p)]·8HO compound, while Ba[Cu(eddadp)]·8HO is proposed to adopt a trans(O ) geometry (two axial acetates) on the basis of density functional theory calculations and comparisons of IR and UV-vis spectral data. Experimental and computed structural data correlating similar copper(II) chelate complexes have been used to better understand the isomerism and departure from regular octahedral geometry within the series. The in-plane O-Cu-N chelate angles show the smallest deviation from the ideal octahedral value of 90°, and hence the lowest strain, for the eddadp complex with two equatorial ß-propionate rings. A linear dependence between tetragonality and the number of five-membered rings has been established. A natural bonding orbital analysis of the series of complexes is also presented.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

This paper describes the horizontal deflection behaviour of a single particle in paramagnetic fluids under a high-gradient superconducting magnetic field. A glass box was designed to carry out experiments and test assumptions. It was found that the particles were deflected away from the magnet bore centre and particles with different density and/or susceptibility settled at a certain position on the container floor due to the combined forces of gravity and magneto-Archimedes as well as lateral buoyant (displacement) force. Matlab was chosen to simulate the movement of the particle in the magnetic fluid, the simulation results were in good accordance with experimental data. The results presented here, though, are still very much in their infancy, which could potentially form the basis of a new approach to separating materials based on a combination of density and susceptibility. Graphical abstract: [Figure not available: see fulltext.] © 2014 EDP Sciences, SIF, Springer-Verlag Berlin Heidelberg.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

In the global economy, innovation is one of the most important competitive assets for companies willing to compete in international markets. As competition moves from standardised products to customised ones, depending on each specific market needs, economies of scale are not anymore the only winning strategy. Innovation requires firms to establish processes to acquire and absorb new knowledge, leading to the recent theory of Open Innovation. Knowledge sharing and acquisition happens when firms are embedded in networks with other firms, university, institutions and many other economic actors. Several typologies of innovation and firm networks have been identified, with various geographical spans. One of the first being modelled was the Industrial Cluster (or in Italian Distretto Industriale) which was for long considered the benchmark for innovation and economic development. Other kind of networks have been modelled since the late 1970s; Regional Innovation Systems represent one of the latest and more diffuse model of innovation networks, specifically introduced to combine local networks and the global economy. This model was qualitatively exploited since its introduction, but, together with National Innovation Systems, is among the most inspiring for policy makers and is often cited by them, not always properly. The aim of this research is to setup an econometric model describing Regional Innovation Systems, becoming one the first attempts to test and enhance this theory with a quantitative approach. A dataset of 104 secondary and primary data from European regions was built in order to run a multiple linear regression, testing if Regional Innovation Systems are really correlated to regional innovation and regional innovation in cooperation with foreign partners. Furthermore, an exploratory multiple linear regression was performed to verify which variables, among those describing a Regional Innovation Systems, are the most significant for innovating, alone or with foreign partners. Furthermore, the effectiveness of present innovation policies has been tested based on the findings of the econometric model. The developed model confirmed the role of Regional Innovation Systems for creating innovation even in cooperation with international partners: this represents one of the firsts quantitative confirmation of a theory previously based on qualitative models only. Furthermore the results of this model confirmed a minor influence of National Innovation Systems: comparing the analysis of existing innovation policies, both at regional and national level, to our findings, emerged the need for potential a pivotal change in the direction currently followed by policy makers. Last, while confirming the role of the presence a learning environment in a region and the catalyst role of regional administration, this research offers a potential new perspective for the whole private sector in creating a Regional Innovation System.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

The aim of this book is to consider theoretically the notion of the global competitiveness of regions, as well as giving attention as to how such competitiveness may be empirically measured. With this in mind, the book has three specific objectives: first, to place the concept of regional competitiveness within the context of regional economic development theory; second, to present a rationale and method for quantifying the global competitiveness of regions; and, third, to undertake the most geographically widespread analysis of regional competitiveness differences across the globe. With regard to the third goal, the analysis incorporates more than 500 regions across Europe, North and South America, Asia-Pacific, the Middle East, and the so-called BRIC economies of Brazil, Russia, India, and China. The importance of the concept of competitiveness has increased rapidly in recent years, with the issues surrounding it becoming, at the same time, more empirically refined and theoretically complex. The focus on regions reflects the growing consensus that they are the primary spatial units that compete to attract investment, and it is at the regional level that knowledge is circulated and transferred, resulting in agglomerations, or clusters, of industrial and service sector enterprises. This growing acknowledgement of the region’s role as a key spatial unit of organisation has led to attention turning to competitiveness at a more regional level. The book explores the results of the World Competitiveness Index of Regions (WCIR), covering the rankings and results of the 2014 edition. The WCIR provides a tool for analysing the development of a range of regional economies across the globe. It enables an illustration of the changing patterns of regional competitiveness on the international stage to be generated. In fundamental terms, the WCIR aims to produce an integrated and overall benchmark of the knowledge capacity, capability, and sustainability of each region, and the extent to which this knowledge is translated into economic value and transferred into the wealth of the citizens of each region.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

DUE TO COPYRIGHT RESTRICTIONS ONLY AVAILABLE FOR CONSULTATION AT ASTON UNIVERSITY LIBRARY AND INFORMATION SERVICES WITH PRIOR ARRANGEMENT The research presented in this thesis is concerned with Discrete-Event Simulation (DES) modelling as a method to facilitate logistical policy development within the UK Less-than-Truckload (LTL) freight distribution sector which has been typified by “Pallet Networks” operating on a hub-and-spoke philosophy. Current literature relating to LTL hub-and-spoke and cross-dock freight distribution systems traditionally examines a variety of network and hub design configurations. Each is consistent with classical notions of creating process efficiency, improving productivity, reducing costs and generally creating economies of scale through notions of bulk optimisation. Whilst there is a growing abundance of papers discussing both the network design and hub operational components mentioned above, there is a shortcoming in the overall analysis when it comes to discussing the “spoke-terminal” of hub-and-spoke freight distribution systems and their capabilities for handling the diverse and discrete customer profiles of freight that multi-user LTL hub-and-spoke networks typically handle over the “last-mile” of the delivery, in particular, a mix of retail and non-retail customers. A simulation study is undertaken to investigate the impact on operational performance when the current combined spoke-terminal delivery tours are separated by ‘profile-type’ (i.e. retail or nonretail). The results indicate that a potential improvement in delivery performance can be made by separating retail and non-retail delivery runs at the spoke-terminal and that dedicated retail and non-retail delivery tours could be adopted in order to improve customer delivery requirements and adapt hub-deployed policies. The study also leverages key operator experiences to highlight the main practical implementation challenges when integrating the observed simulation results into the real-world. The study concludes that DES be harnessed as an enabling device to develop a ‘guide policy’. This policy needs to be flexible and should be applied in stages, taking into account the growing retail-exposure.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

A következőkben arra teszünk kísérletet, hogy összegezzük a közép- és a kelet-európai rendszerváltozások és az ezt tanulmányozók fordulatos történetét az elmúlt két évtizedben. Bemutatjuk, hogy a közgazdaságtan egy kevéssé fejlett ága miképp szembesült a tudományág egésze szempontjából is talán legnehezebb értelmezési és alkalmazási kérdéseket fölvető történelmi folyamattal. Megpróbáljuk feloldani azt a rejtvényt, hogy a főáramú megközelítés megismerése és alkalmazása miért nem hozott átütő eredményt sem a térség gazdaságainak, sem magának a tudományszaknak. Megvizsgáljuk a fokozatosság és a reformok kritikus tömege viszonyát. Végül kísérletet teszünk arra, hogy e sajátos szakterület elemzéséből adódó, tartósnak bizonyuló tételeket beépítsük a fenntartható fejlődés szélesebben értelmezett, immár főáramú megközelítéseibe. ___________ The article attempts to give an account of the changes of system in Central and Eastern Europe and of those who studied them in the last two decades. It shows how a less devel-oped branch of economics faced a historical process that posed possibly the most difficult questions of interpretation and application for the whole discipline. An attempt is made to discover why recognition and application of the mainstream approach failed to bring resounding success for the economies of the region or for economics itself. The author examines the relation between continuity and the critical weight of reforms. Finally, an attempt is made to advance durable propositions based on analysis of this specific field through now mainstream approaches in terms of sustainable development.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Access to the Internet has grown exponentially in Latin America over the past decade. The International Telecommunications Union (ITU) estimates that in 2009 there were 144.5 million Internet users in South America, 6.4 million in Central America, and 8.2 million in the Caribbean, or a total 159.2 million users in all of Latin America.1 At that time, ITU reported an estimated 31 million Internet users in Mexico, which would bring the overall number of users in Latin America to 190.2 million people. More recent estimates published by Internet World Stats place Internet access currently at an estimated 204.6 million out of a total population of 592.5 million in the region (this figure includes Mexico).2 According to those figures, 34.5 per cent of the Latin American population now enjoys Internet access. In recent years, universal access policies contributed to the vast increase in digital literacy and Internet use in Argentina, Brazil, Chile, Colombia, and Costa Rica. Whereas the latter was the first country in the region to adopt a policy of universal access, the most expansive and successful digital inclusion programs in the region have taken hold in Brazil and Chile. These two countries have allocated considerable resources to the promotion of digital literacy and Internet access among low income and poor populations; in both cases, civil society groups significantly assisted in the promotion of inclusion at the grassroots level. Digital literacy and Internet access have come to represent, particularly in the area of education, a welcome complementary resource for populations chronically underserved in nations with a long-standing record of inadequate public social services. Digital inclusion is vastly expanding throughout the region, thanks to stabilizing economies, increasingly affordable technology, and the rapid growth in the supply of cellular mobile telephony. A recent study by the global advertising agency Razorfish revealed significant shifts in the demographics of digital inclusion in the major economies of South America, where Web access is rapidly increasing amid the lower middle class and the working poor.3 Several researchers have suggested that Internet access will bring about greater civic participation and engagement, although skeptics remain unsure this could happen in Latin America. Yet, there have been some recent instances of political mobilization facilitated through the use of the Web and social media applications, starting in Chile when “smart mobs” nationwide demonstrated against former Chilean President Michelle Bachelet when she failed to enact education reforms in May 2006. The Internet has also been used by marginalized groups and by guerrillas groups to highlight their stories. In sum, Internet access in Latin is no longer a medium restricted to the elite. It is rather a public sphere upon which civil society has staked its claim. Some of the examples noted in this study point toward a developing trend whereby civil society, through online grassroots movements, is able to effectively pressure public officials, instill transparency and demand accountability in government. Access to the Internet has also made it possible for voices on the margins to participate in the conversation in a way that was never previously feasible. 1 International Telecommunications Union [ITU], “Information Technology Public & Report,” accessed May 15, 2011, http://www.itu.int/. 2 Internet World Stats, “Internet Usage Statistics for the Americas,” accessed March 24, 2011, http://www.internetworldstats.com/stats2.htm 3 J. Crump, “The finch and the fox,” London, UK (2010), http://www.slideshare.net/razorfishmarketing/the-finch-and-the-fox.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Taken together, the six nations of Central America count a population of roughly 40 million people and an energy market equal in size to that of Colombia, sufficient to benefit from economies of scale. The region has traditionally been a net importer of hydrocarbons, and hydroelectricity has dominated electric generation. But more recently, thermoelectric generation (diesel and fuel oil) has greatly increased as a percentage of the regional generation market. Progress has been made across the region’s electric sector, beginning with reforms in the 1990s and the 1996 signing of a regional treaty aimed at the development of a regional energy integration project – the Central American Electrical Interconnection System, or SIEPAC. A fundamental SIEPAC goal is to set up a regional electric market and a regulatory system. Indeed, after many years of development, SIEPAC is poised to open a new chapter in Central America’s electric infrastructure and market. But this new era must contend with critical issues such as the need to consolidate the regional electric market, political issues surrounding the venture, and security concerns. Moreover, local conflicts, in different degrees, have become priorities for policymakers, and these are possible barriers to completing the project. The goals of the SIEPAC project and of deepening the broader electric integration process are possible if national and regional decision makers understand that cooperative decision making will produce better results than separate national decision making. Enhanced regional understanding and cooperative decision making, combined with an effort to reorient the terminology and dialogue vis-à-vis energy efficiency in Central America, form the core recommendations of this paper.