947 resultados para Direct integration method


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The Mathematica system (version 4.0) is employed in the solution of nonlinear difusion and convection-difusion problems, formulated as transient one-dimensional partial diferential equations with potential dependent equation coefficients. The Generalized Integral Transform Technique (GITT) is first implemented for the hybrid numerical-analytical solution of such classes of problems, through the symbolic integral transformation and elimination of the space variable, followed by the utilization of the built-in Mathematica function NDSolve for handling the resulting transformed ODE system. This approach ofers an error-controlled final numerical solution, through the simultaneous control of local errors in this reliable ODE's solver and of the proposed eigenfunction expansion truncation order. For covalidation purposes, the same built-in function NDSolve is employed in the direct solution of these partial diferential equations, as made possible by the algorithms implemented in Mathematica (versions 3.0 and up), based on application of the method of lines. Various numerical experiments are performed and relative merits of each approach are critically pointed out.

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In this work, we present the solution of a class of linear inverse heat conduction problems for the estimation of unknown heat source terms, with no prior information of the functional forms of timewise and spatial dependence of the source strength, using the conjugate gradient method with an adjoint problem. After describing the mathematical formulation of a general direct problem and the procedure for the solution of the inverse problem, we show applications to three transient heat transfer problems: a one-dimensional cylindrical problem; a two-dimensional cylindrical problem; and a one-dimensional problem with two plates.

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We apply the Bogoliubov Averaging Method to the study of the vibrations of an elastic foundation, forced by a Non-ideal energy source. The considered model consists of a portal plane frame with quadratic nonlinearities, with internal resonance 1:2, supporting a direct current motor with limited power. The non-ideal excitation is in primary resonance in the order of one-half with the second mode frequency. The results of the averaging method, plotted in time evolution curve and phase diagrams are compared to those obtained by numerically integrating of the original differential equations. The presence of the saturation phenomenon is verified by analytical procedures.

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Fiber-reinforced composites (FRCs) are a new group of non-metallic biomaterials showing a growing popularity in many dental and medical applications. As an oral implant material, FRC is biocompatible in bone tissue environment. Soft tissue integration to FRC polymer material is unclear. This series of in vitro studies aimed at evaluating unidirectional E-glass FRC polymer in terms of mechanical, chemical, and biological properties in an attempt to develop a new non-metallic oral implant abutment alternative. Two different types of substrates were investigated: (a) Plain polymer (BisGMA 50%–TEGDMA 50%) and (b) Unidirectional FRC. The mechanical behavior of high fiber-density FRCs was assessed using a three-point bending test. Surface characterization was performed using scanning electron and spinning disk confocal microscopes. The surface wettability/energy was determined using sessile drop method. The blood response, including blood-clotting ability and platelet morphology was evaluated. Human gingival fibroblast cell responses - adhesion kinetics, adhesion strength, and proliferation activity - were studied in cell culture environment using routine test conditions. A novel tissue culture method was developed and used to evaluate porcine gingival tissue graft attachment and growth on the experimental composite implants. The analysis of the mechanical properties showed that there is a direct proportionality in the relationship between E-glass fiber volume fraction and toughness, modulus of elasticity, and load bearing capacity; however, flexural strength did not show significant improvement when high fiber-density FRC is used. FRCs showed moderate hydrophilic properties owing to the presence of exposed glass fibers on the polymer surface. Blood-clotting time was shorter on FRC substrates than on plain polymer. The FRC substrates also showed higher platelet activation state than plain polymer substrates. Fibroblast cell adhesion strength and proliferation rate were highly pronounced on FRCs. A tissue culture study revealed that gingival epithelium and connective tissue established an immediate close contact with both plain polymer and FRC implants. However, FRC seemed to guide epithelial migration outwards from the tissue/implant interface. Due to the anisotropic and hydrophilic nature of FRC, it can be concluded that this material enhances biological events related with soft tissue integration on oral implant surface.

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Yandex is the dominant search engine in Russia, followed by the world leader Google. This study focuses on the performance differences between the two in search advertising in the context of tourism, by running two identical campaigns and measuring the KPI’s, such as CPA (cost-per-action), on both campaigns. Search engine advertising is a new and fast changing form of advertising, which should be studied frequently in order to keep up with the changes. Research was done as an experimental study in cooperation with a Finnish tourism company and the data is gathered from the clickstream and not from questionnaires, which is recommended method by the literature. The results of the study suggests that Yandex.Direct performed better in the selected niche and that the individual campaign planning for Yandex.Direct and Google AdWords is an important part of the optimization of search advertising in Russia.

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A fast changing dynamic business environment is becoming a norm today in different areas, including retailing. The aims of this study are to explore existing store formats of branded sportswear retailing and their characteristics, and to identify the trends which might shape their future. The ultimate goal, however, is to create and analyze images of the future of branded sportswear retailing in Germany 2030 by applying the methods of futures studies. As theoretical background, the cyclical theories of retail evolution have been used. Empirical material is obtained by conducting a Disaggregative Policy Delphi method based study, the aim of which is to obtain well–argued qualitative and quantitative information from experts about store format development in order to create future images based on cluster analysis. Flagship stores, Concept stores, Factory Outlets, Pop-up stores, E-commerce and M-commerce represent the diversity of store formats existing in Germany today. They have different aims, roles, and advantages which retailers try to leverage. However such trends as multichannel integration, technological enhancements, growing popularity of online channels, switching customer behaviors, customization and personalization, and economic turbulence might shape the future of sportswear retailing. Four future images constructed: “Multichannel Integration”, “Smart and Personal”, “Consumer Diversification”, and “Always Online” – describe alternative futures of German branded sportswear store formats in 2030 based on different trends, assumptions, hopes and fears. They also point out uncertainties in retailing such as cannibalization of channels, the growing power and expectations of consumers, the complexity of multichannel synergies, and the switching customer behavior. Constructed future images, thus, provide readers with an opportunity to imagine and explore alternative states of the future of branded sportswear store formats in Germany 2030. They could serve well as a tool to communicate the results to decision–makers, compare them, and to analyze to inspire and direct actions for a better future tomorrow.

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Digital business ecosystems (DBE) are becoming an increasingly popular concept for modelling and building distributed systems in heterogeneous, decentralized and open environments. Information- and communication technology (ICT) enabled business solutions have created an opportunity for automated business relations and transactions. The deployment of ICT in business-to-business (B2B) integration seeks to improve competitiveness by establishing real-time information and offering better information visibility to business ecosystem actors. The products, components and raw material flows in supply chains are traditionally studied in logistics research. In this study, we expand the research to cover the processes parallel to the service and information flows as information logistics integration. In this thesis, we show how better integration and automation of information flows enhance the speed of processes and, thus, provide cost savings and other benefits for organizations. Investments in DBE are intended to add value through business automation and are key decisions in building up information logistics integration. Business solutions that build on automation are important sources of value in networks that promote and support business relations and transactions. Value is created through improved productivity and effectiveness when new, more efficient collaboration methods are discovered and integrated into DBE. Organizations, business networks and collaborations, even with competitors, form DBE in which information logistics integration has a significant role as a value driver. However, traditional economic and computing theories do not focus on digital business ecosystems as a separate form of organization, and they do not provide conceptual frameworks that can be used to explore digital business ecosystems as value drivers—combined internal management and external coordination mechanisms for information logistics integration are not the current practice of a company’s strategic process. In this thesis, we have developed and tested a framework to explore the digital business ecosystems developed and a coordination model for digital business ecosystem integration; moreover, we have analysed the value of information logistics integration. The research is based on a case study and on mixed methods, in which we use the Delphi method and Internetbased tools for idea generation and development. We conducted many interviews with key experts, which we recoded, transcribed and coded to find success factors. Qualitative analyses were based on a Monte Carlo simulation, which sought cost savings, and Real Option Valuation, which sought an optimal investment program for the ecosystem level. This study provides valuable knowledge regarding information logistics integration by utilizing a suitable business process information model for collaboration. An information model is based on the business process scenarios and on detailed transactions for the mapping and automation of product, service and information flows. The research results illustrate the current cap of understanding information logistics integration in a digital business ecosystem. Based on success factors, we were able to illustrate how specific coordination mechanisms related to network management and orchestration could be designed. We also pointed out the potential of information logistics integration in value creation. With the help of global standardization experts, we utilized the design of the core information model for B2B integration. We built this quantitative analysis by using the Monte Carlo-based simulation model and the Real Option Value model. This research covers relevant new research disciplines, such as information logistics integration and digital business ecosystems, in which the current literature needs to be improved. This research was executed by high-level experts and managers responsible for global business network B2B integration. However, the research was dominated by one industry domain, and therefore a more comprehensive exploration should be undertaken to cover a larger population of business sectors. Based on this research, the new quantitative survey could provide new possibilities to examine information logistics integration in digital business ecosystems. The value activities indicate that further studies should continue, especially with regard to the collaboration issues on integration, focusing on a user-centric approach. We should better understand how real-time information supports customer value creation by imbedding the information into the lifetime value of products and services. The aim of this research was to build competitive advantage through B2B integration to support a real-time economy. For practitioners, this research created several tools and concepts to improve value activities, information logistics integration design and management and orchestration models. Based on the results, the companies were able to better understand the formulation of the digital business ecosystem and the importance of joint efforts in collaboration. However, the challenge of incorporating this new knowledge into strategic processes in a multi-stakeholder environment remains. This challenge has been noted, and new projects have been established in pursuit of a real-time economy.

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Thesis: A liquid-cooled, direct-drive, permanent-magnet, synchronous generator with helical, double-layer, non-overlapping windings formed from a copper conductor with a coaxial internal coolant conduit offers an excellent combination of attributes to reliably provide economic wind power for the coming generation of wind turbines with power ratings between 5 and 20MW. A generator based on the liquid-cooled architecture proposed here will be reliable and cost effective. Its smaller size and mass will reduce build, transport, and installation costs. Summary: Converting wind energy into electricity and transmitting it to an electrical power grid to supply consumers is a relatively new and rapidly developing method of electricity generation. In the most recent decade, the increase in wind energy’s share of overall energy production has been remarkable. Thousands of land-based and offshore wind turbines have been commissioned around the globe, and thousands more are being planned. The technologies have evolved rapidly and are continuing to evolve, and wind turbine sizes and power ratings are continually increasing. Many of the newer wind turbine designs feature drivetrains based on Direct-Drive, Permanent-Magnet, Synchronous Generators (DD-PMSGs). Being low-speed high-torque machines, the diameters of air-cooled DD-PMSGs become very large to generate higher levels of power. The largest direct-drive wind turbine generator in operation today, rated just below 8MW, is 12m in diameter and approximately 220 tonne. To generate higher powers, traditional DD-PMSGs would need to become extraordinarily large. A 15MW air-cooled direct-drive generator would be of colossal size and tremendous mass and no longer economically viable. One alternative to increasing diameter is instead to increase torque density. In a permanent magnet machine, this is best done by increasing the linear current density of the stator windings. However, greater linear current density results in more Joule heating, and the additional heat cannot be removed practically using a traditional air-cooling approach. Direct liquid cooling is more effective, and when applied directly to the stator windings, higher linear current densities can be sustained leading to substantial increases in torque density. The higher torque density, in turn, makes possible significant reductions in DD-PMSG size. Over the past five years, a multidisciplinary team of researchers has applied a holistic approach to explore the application of liquid cooling to permanent-magnet wind turbine generator design. The approach has considered wind energy markets and the economics of wind power, system reliability, electromagnetic behaviors and design, thermal design and performance, mechanical architecture and behaviors, and the performance modeling of installed wind turbines. This dissertation is based on seven publications that chronicle the work. The primary outcomes are the proposal of a novel generator architecture, a multidisciplinary set of analyses to predict the behaviors, and experimentation to demonstrate some of the key principles and validate the analyses. The proposed generator concept is a direct-drive, surface-magnet, synchronous generator with fractional-slot, duplex-helical, double-layer, non-overlapping windings formed from a copper conductor with a coaxial internal coolant conduit to accommodate liquid coolant flow. The novel liquid-cooling architecture is referred to as LC DD-PMSG. The first of the seven publications summarized in this dissertation discusses the technological and economic benefits and limitations of DD-PMSGs as applied to wind energy. The second publication addresses the long-term reliability of the proposed LC DD-PMSG design. Publication 3 examines the machine’s electromagnetic design, and Publication 4 introduces an optimization tool developed to quickly define basic machine parameters. The static and harmonic behaviors of the stator and rotor wheel structures are the subject of Publication 5. And finally, Publications 6 and 7 examine steady-state and transient thermal behaviors. There have been a number of ancillary concrete outcomes associated with the work including the following. X Intellectual Property (IP) for direct liquid cooling of stator windings via an embedded coaxial coolant conduit, IP for a lightweight wheel structure for lowspeed, high-torque electrical machinery, and IP for numerous other details of the LC DD-PMSG design X Analytical demonstrations of the equivalent reliability of the LC DD-PMSG; validated electromagnetic, thermal, structural, and dynamic prediction models; and an analytical demonstration of the superior partial load efficiency and annual energy output of an LC DD-PMSG design X A set of LC DD-PMSG design guidelines and an analytical tool to establish optimal geometries quickly and early on X Proposed 8 MW LC DD-PMSG concepts for both inner and outer rotor configurations Furthermore, three technologies introduced could be relevant across a broader spectrum of applications. 1) The cost optimization methodology developed as part of this work could be further improved to produce a simple tool to establish base geometries for various electromagnetic machine types. 2) The layered sheet-steel element construction technology used for the LC DD-PMSG stator and rotor wheel structures has potential for a wide range of applications. And finally, 3) the direct liquid-cooling technology could be beneficial in higher speed electromotive applications such as vehicular electric drives.

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The design process of direct-driven permanent magnet synchronous machines (PMSMs) for a full electric 4 ´ 4 sports car is presented. The rotor structure of the machine consists of two permanent magnet layers embedded inside the rotor laminations thus resulting in some inverse saliency, where the q-axis inductance is larger than the d-axis one. An integer slot stator winding was selected to fully take advantage of the additional reluctance torque. The performance characteristics of the designed PMSMs were calculated by applying a twodimensional finite element method. Cross-saturation between the d- and q-axes was taken into account in the calculation of the synchronous inductances. The calculation results are validated by measurements.

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The objective of the present study was to investigate the effects of the direct addition of pentoxifylline (PF) to the ejaculates of men with poor sperm quality before freezing on post-thaw sperm motility, viability, acrosome integrity, and agonist-induced acrosome reaction. Semen specimens from 16 infertile men with impaired sperm count and motility (oligoasthenozoospermia) were divided into two equal aliquots: one received no treatment (control) while the other was incubated with 5 mM PF (treated). Both aliquots were cryopreserved by the liquid nitrogen vapor method. Motility was assessed according to WHO criteria. Acrosome integrity and spontaneous and calcium ionophore-induced acrosome reactions were assessed with fluorescein isothiocyanate-conjugated peanut agglutinin combined with a supra-vital dye (Hoechst-33258). Cryopreservation impaired sperm motility (percentage reduction: 87.4 (interquartile range, IQ: 70.3-92.9) vs 89.1 (IQ: 72.7-96.0%)), viability (25.9 (IQ: 22.2-29.7) vs 25.6 (IQ: 19.7-40.3%)) and acrosome integrity (18.9 (IQ: 5.4-38.9) vs 26.8 (IQ: 0.0-45.2%)) to the same extent in both treated and control aliquots. However, PF treatment before freezing improved the acrosome reaction to ionophore challenge test scores in cryopreserved spermatozoa (9.7 (IQ: 6.6-19.7) vs 4.8 (IQ: 0.5-6.8%); P = 0.002). These data show that pre-freeze treatment of poor quality human sperm with pentoxifylline did not improve post-thaw motility or viability nor did it prevent acrosomal loss during the freeze-thaw process. However, PF, as used, improved the ability of thawed spermatozoa to undergo the acrosome reaction in response to calcium ionophore. The present data indicate that treatment of poor quality human sperm with PF may enhance post-thaw sperm fertilizing ability.

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Solar and wind power produce electricity irregularly. This irregular power production is problematic and therefore production can exceed the need. Thus sufficient energy storage solutions are needed. Currently there are some storages, such as flywheel, but they are quite short-term. Power-to-Gas (P2G) offers a solution to store energy as a synthetic natural gas. It also improves nation’s energy self-sufficiency. Power-to-Gas can be integrated to an industrial or a municipal facility to reduce production costs. In this master’s thesis the integration of Power-to-Gas technologies to wastewater treatment as a part of the VTT’s Neo-Carbon Energy project is studied. Power-to-Gas produces synthetic methane (SNG) from water and carbon dioxide with electricity. This SNG can be considered as stored energy. Basic wastewater treatment technologies and the production of biogas in the treatment plant are studied. The utilisation of biogas and SNG in heat and power production and in transportation is also studied. The integration of the P2G to wastewater treatment plant (WWTP) is examined mainly from economic view. First the mass flows of flowing materials are calculated and after that the economic impact based on the mass flows. The economic efficiency is evaluated with Net Present Value method. In this thesis it is also studied the overall profitability of the integration and the key economic factors.

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The aim of this master’s thesis is to provide a real life example of how marketing research data is used by different functions in the NPD process. In order to achieve this goal, a case study in a company was implemented where gathering, analysis, distribution and synthesis of marketing research data in NPD were studied. The main research question was formulated as follows: How is marketing research data integrated and used by different company functions in the NPD process? The theory part of the master’s thesis was focused on the discussion of the marketing function role in NPD, use of marketing research particularly in the food industry, as well as issues related to the marketing/R&D interface during the NPD process. The empirical part of the master’s thesis was based on qualitative explanatory case study research. Individual in-depth interviews with company representatives, company documents and online research were used for data collection and analyzed through triangulation method. The empirical findings advocate that the most important marketing data sources at the concept generation stage of NPD are: global trends monitoring, retailing audit and consumers insights. These data sets are crucial for establishing the potential of the product on the market and defining the desired features for the new product to be developed. The findings also suggest the example of successful crossfunctional communication during the NPD process with formal and informal communication patterns. General managerial recommendations are given on the integration in NPD of a strategy, process, continuous improvement, and motivated cross-functional product development teams.

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The lack of research of private real estate is a well-known problem. Earlier studies have mostly concentrated on the USA or the UK. Therefore, this master thesis offers more information about the performance and risk associated with private real estate investments in Nordic countries, but especially in Finland. The structure of this master thesis is divided into two independent sections based on the research questions. In first section, database analysis is performed to assess risk-return ratio of direct real estate investment for Nordic countries. Risk-return ratios are also assessed for different property sectors and economic regions. Finally, review of diversification strategies based on property sectors and economic regions is performed. However, standard deviation itself is not usually sufficient method to evaluate riskiness of private real estate. There is demand for more explicit assessment of property risk. One solution is property risk scoring. In second section risk scorecard based tool is built to make different real estate comparable in terms of risk. In order to do this, nine real estate professionals were interviewed to enhance the structure of theory-based risk scorecard and to assess weights for different risk factors.

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Russia approved ambitious reform plan for the electricity sector in 2001 including privatisation of the country’s huge thermal generation assets. So far the sector had suffered from power shortages, aging infrastructure, substantial electricity losses, and weak productivity and profitability numbers. There was obvious need for foreign investments and technologies. The reform was rather successful; the generation assets were privatised in auctions in 2007-2008 and three European energy companies, E.On, Enel and Fortum, invested in and obtained together over 10% of the Russian production assets. The novelty of these foreign investments serves unique object for the study. The political risk is involved in the FDI due to the industry’s social and economic importance. The research’s objective was to identify and analyse the political risk that foreign investors face in the Russian electricity sector. The research had qualitative study method and the empirical data was collected by interviewing. The research’s theoretical framework was based on the existing political risk theories and it focused to understand the Russian government in relation to the country’s stability and define both macro-level and micro-level sources of political risk for the foreign direct investments in the sector. The research concludes that the centralised and obscure political decision-making, economic constriction, high level of governmental control in economy and corruption form the country’s internal macro-level risk sources for the foreign investors in the sector. Additionally the retribution due to the companies’ home country actions, possible violent confrontations at the Russian borders and the currency instability are externally originated risk sources. In the electricity industry there is risk of tightened governmental control and increased regulation and taxation. Similarly the company-level risk sources link to the unreformed heating sector, bargaining with the authorities, diplomatic stress between host and home countries and to companies and government’s divergent perspective for the profit-making. The research stresses the foreign companies’ ability to cope with the characteristics of Russian political environment. In addition to frequent political and market risk assessment, the companies need to focus on currency protection against rouble’s rate fluctuation and actively build good company-citizenship in the country. Good relationship is needed with the Russian political authorities. The political risk identification and the research’s conclusive framework also enable political risk study assessments for other industries in Russia

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Adenoviral vectors are currently the most widely used gene therapeutic vectors, but their inability to integrate into host chromosomal DNA shortened their transgene expression and limited their use in clinical trials. In this project, we initially planned to develop a technique to test the effect of the early region 1 (E1) on adenovirus integration by comparing the integration efficiencies between an E1-deleted adenoviral vector (SubE1) and an Elcontaining vector (SubE3). However, we did not harvest any SubE3 virus, even if we repeated the transfection and successfully rescued the SubE1 virus (2/4 transfections generated viruses) and positive control virus (6/6). The failure of rescuing SubE3 could be caused by the instability of the genomic plasmid pFG173, as it had frequent intemal deletions when we were purifying It. Therefore, we developed techniques to test the effect of E1 on homologous recombination (HR) since literature suggested that adenovirus integration is initiated by HR. We attempted to silence the E1 in 293 cells by transfecting E1A/B-specific small interfering RNA (siRNA). However, no silenced phenotype was observed, even if we varied the concentrations of E1A/B siRNA (from 30 nM to 270 nM) and checked the silencing effects at different time points (48, 72, 96 h). One possible explanation would be that the E1A/B siRNA sequences are not potent enough to Induce the silenced phenotype. For evaluating HR efficiencies, an HR assay system based on bacterial transfonmatJon was designed. We constmcted two plasmids ( designated as pUC19-dl1 and pUC19-dl2) containing different defective lacZa cassettes (forming white colonies after transformation) that can generate a functional lacZa cassette (forming blue colonies) through HR after transfecting into 293 cells. The HR efficiencies would be expressed as the percentages of the blue colonies among all the colonies. Unfortunately, after transfonnation of plasmid isolated from 293 cells, no colony was found, even at a transformation efficiency of 1.8x10^ colonies/pg pUC19, suggesting the sensitivity of this system was low. To enhance the sensitivity, PCR was used. We designed a set of primers that can only amplify the recombinant plasmid fomied through HR. Therefore, the HR efficiencies among different treatments can be evaluated by the amplification results, and this system could be used to test the effect of E1 region on adenovirus integration. In addition, to our knowledge there was no previous studies using PCR/ Realtime PCR to evaluate HR efficiency, so this system also provides a PCR-based method to carry out the HR assays.