851 resultados para Large-scale enterprises
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To tackle the challenges at circuit level and system level VLSI and embedded system design, this dissertation proposes various novel algorithms to explore the efficient solutions. At the circuit level, a new reliability-driven minimum cost Steiner routing and layer assignment scheme is proposed, and the first transceiver insertion algorithmic framework for the optical interconnect is proposed. At the system level, a reliability-driven task scheduling scheme for multiprocessor real-time embedded systems, which optimizes system energy consumption under stochastic fault occurrences, is proposed. The embedded system design is also widely used in the smart home area for improving health, wellbeing and quality of life. The proposed scheduling scheme for multiprocessor embedded systems is hence extended to handle the energy consumption scheduling issues for smart homes. The extended scheme can arrange the household appliances for operation to minimize monetary expense of a customer based on the time-varying pricing model.
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This study presents a computational parametric analysis of DME steam reforming in a large scale Circulating Fluidized Bed (CFB) reactor. The Computational Fluid Dynamic (CFD) model used, which is based on Eulerian-Eulerian dispersed flow, has been developed and validated in Part I of this study [1]. The effect of the reactor inlet configuration, gas residence time, inlet temperature and steam to DME ratio on the overall reactor performance and products have all been investigated. The results have shown that the use of double sided solid feeding system remarkable improvement in the flow uniformity, but with limited effect on the reactions and products. The temperature has been found to play a dominant role in increasing the DME conversion and the hydrogen yield. According to the parametric analysis, it is recommended to run the CFB reactor at around 300 °C inlet temperature, 5.5 steam to DME molar ratio, 4 s gas residence time and 37,104 ml gcat -1 h-1 space velocity. At these conditions, the DME conversion and hydrogen molar concentration in the product gas were both found to be around 80%.
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Some color centers in diamond can serve as quantum bits which can be manipulated with microwave pulses and read out with laser, even at room temperature. However, the photon collection efficiency of bulk diamond is greatly reduced by refraction at the diamond/air interface. To address this issue, we fabricated arrays of diamond nanostructures, differing in both diameter and top end shape, with HSQ and Cr as the etching mask materials, aiming toward large scale fabrication of single-photon sources with enhanced collection efficiency made of nitrogen vacancy (NV) embedded diamond. With a mixture of O2 and CHF3 gas plasma, diamond pillars with diameters down to 45 nm were obtained. The top end shape evolution has been represented with a simple model. The tests of size dependent single-photon properties confirmed an improved single-photon collection efficiency enhancement, larger than tenfold, and a mild decrease of decoherence time with decreasing pillar diameter was observed as expected. These results provide useful information for future applications of nanostructured diamond as a single-photon source.
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Spread of antibiotic resistance among bacteria responsible for nosocomial and community-acquired infections urges for novel therapeutic or prophylactic targets and for innovative pathogen-specific antibacterial compounds. Major challenges are posed by opportunistic pathogens belonging to the low GC% gram-positive bacteria. Among those, Enterococcus faecalis is a leading cause of hospital-acquired infections associated with life-threatening issues and increased hospital costs. To better understand the molecular properties of enterococci that may be required for virulence, and that may explain the emergence of these bacteria in nosocomial infections, we performed the first large-scale functional analysis of E. faecalis V583, the first vancomycin-resistant isolate from a human bloodstream infection. E. faecalis V583 is within the high-risk clonal complex 2 group, which comprises mostly isolates derived from hospital infections worldwide. We conducted broad-range screenings of candidate genes likely involved in host adaptation (e.g., colonization and/or virulence). For this purpose, a library was constructed of targeted insertion mutations in 177 genes encoding putative surface or stress-response factors. Individual mutants were subsequently tested for their i) resistance to oxidative stress, ii) antibiotic resistance, iii) resistance to opsonophagocytosis, iv) adherence to the human colon carcinoma Caco-2 epithelial cells and v) virulence in a surrogate insect model. Our results identified a number of factors that are involved in the interaction between enterococci and their host environments. Their predicted functions highlight the importance of cell envelope glycopolymers in E. faecalis host adaptation. This study provides a valuable genetic database for understanding the steps leading E. faecalis to opportunistic virulence.
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Strong convective events can produce extreme precipitation, hail, lightning or gusts, potentially inducing severe socio-economic impacts. These events have a relatively small spatial extension and, in most cases, a short lifetime. In this study, a model is developed for estimating convective extreme events based on large scale conditions. It is shown that strong convective events can be characterized by a Weibull distribution of radar-based rainfall with a low shape and high scale parameter value. A radius of 90km around a station reporting a convective situation turned out to be suitable. A methodology is developed to estimate the Weibull parameters and thus the occurrence probability of convective events from large scale atmospheric instability and enhanced near-surface humidity, which are usually found on a larger scale than the convective event itself. Here, the probability for the occurrence of extreme convective events is estimated from the KO-index indicating the stability, and relative humidity at 1000hPa. Both variables are computed from ERA-Interim reanalysis. In a first version of the methodology, these two variables are applied to estimate the spatial rainfall distribution and to estimate the occurrence of a convective event. The developed method shows significant skill in estimating the occurrence of convective events as observed at synoptic stations, lightning measurements, and severe weather reports. In order to take frontal influences into account, a scheme for the detection of atmospheric fronts is implemented. While generally higher instability is found in the vicinity of fronts, the skill of this approach is largely unchanged. Additional improvements were achieved by a bias-correction and the use of ERA-Interim precipitation. The resulting estimation method is applied to the ERA-Interim period (1979-2014) to establish a ranking of estimated convective extreme events. Two strong estimated events that reveal a frontal influence are analysed in detail. As a second application, the method is applied to GCM-based decadal predictions in the period 1979-2014, which were initialized every year. It is shown that decadal predictive skill for convective event frequencies over Germany is found for the first 3-4 years after the initialization.
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Aim Positive regional correlations between biodiversity and human population have been detected for several taxonomic groups and geographical regions. Such correlations could have important conservation implications and have been mainly attributed to ecological factors, with little testing for an artefactual explanation: more populated regions may show higher biodiversity because they are more thoroughly surveyed. We tested the hypothesis that the correlation between people and herptile diversity in Europe is influenced by survey effort
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The increasing integration of renewable energies in the electricity grid contributes considerably to achieve the European Union goals on energy and Greenhouse Gases (GHG) emissions reduction. However, it also brings problems to grid management. Large scale energy storage can provide the means for a better integration of the renewable energy sources, for balancing supply and demand, to increase energy security, to enhance a better management of the grid and also to converge towards a low carbon economy. Geological formations have the potential to store large volumes of fluids with minimal impact to environment and society. One of the ways to ensure a large scale energy storage is to use the storage capacity in geological reservoir. In fact, there are several viable technologies for underground energy storage, as well as several types of underground reservoirs that can be considered. The geological energy storage technologies considered in this research were: Underground Gas Storage (UGS), Hydrogen Storage (HS), Compressed Air Energy Storage (CAES), Underground Pumped Hydro Storage (UPHS) and Thermal Energy Storage (TES). For these different types of underground energy storage technologies there are several types of geological reservoirs that can be suitable, namely: depleted hydrocarbon reservoirs, aquifers, salt formations and caverns, engineered rock caverns and abandoned mines. Specific site screening criteria are applicable to each of these reservoir types and technologies, which determines the viability of the reservoir itself, and of the technology for any particular site. This paper presents a review of the criteria applied in the scope of the Portuguese contribution to the EU funded project ESTMAP – Energy Storage Mapping and Planning.
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:本文从信息时代对人们认识上的影响,讨论了信息时代对生产、对统一的世界市场、对社会的影响。列举了世界经济进入新的繁荣期的特征。讨论了世界生产的形成和发展,市场竞争的三准则,市场竞争的各个历史阶段及全球化敏捷制造体系迅速发展的原因。分析了二十一世纪制造业面临的形势。详细地讨论了我国国有大中型企业的主要问题:1.产品问题;2.企业结构不合理;3.管理问题;4.质量问题;5.工艺手段和装备落后;6.历史包袱沉重等。提出了利用世界全球化生产体系发展的大好形势的三条对策:1.利用敏捷制造原理对企业进行重组;2.加速产品设计队伍的重建,增强新产品的设计能力;3.利用现代化手段实现现代化管理。
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Research to date on the economic development of the Republic of Korea and Taiwan has frequently contrasted the two economies by depicting the former as centered on large-scale enterprises and the latter on small and medium-size enterprises (SMEs). The purpose of this study is to see if the appropriateness of this perception will also be verified by the statistical data. In Section I the authors utilized census data on the Korean and Taiwanese manufacturing sectors to compare the distribution pattern of the sizes of enterprises in the two economies. However, on examining the available data for making this comparison, the authors discovered that for Korea the statistics provided are those at the level of the establishment (a physical unit engaging in industrial activities such as a factory, workshop, office, or mine) while the statistics for Taiwan are those at the enterprise level. Mindful of this difference, the authors looked at the portion of the economy accounted for by large-scale establishments in Korea that employed 500 workers or more and by enterprises in Taiwan employing the same number of workers, and they discovered that the portion that these large-scale businesses account for, especially in the area of output, has steadily declined since the 1980s. When comparing the share of total production that these large-scale establishments/enterprises account for in the two economies, the authors concluded that those in Korea accounted for a larger share of that economy's production than did their counterparts in Taiwan. The authors then compared the portion of the economy accounted for by establishments in Korea and enterprises in Taiwan that employed less than ten workers, and they found that the portion of the two economies that these very small-scale production units accounted for has also been on the decline. Section II compares the portions of the two economies accounted for by large business groups. After comparing the percentage of GDP accounted for by the total sales of these business groups, the authors found that large business groups in Korea have played a far more important role in Korean economy than has been the case for such groups in Taiwan. This difference in the importance of such business groups in the two economies has also played an significant part in fostering the perceived dichotomy of large-scale enterprises playing the important role in Korea versus SMEs being the important players in Taiwan. Section III compares the percentage of total exports accounted for by SMEs, and shows that SMEs in Taiwan account for a larger share of exports than do their counterparts in Korea. This section also shows that in Taiwan the share of export sales for SMEs has consistently exceeded that for non-SMEs, while in Korea the relationship between enterprise size and the rate of export sales has been directly proportional. This difference in the size of the major export players is another factor fostering the perception of the Korean economy being centered on big business while Taiwan's is on SMEs. Although there were difficulties and limitations when comparing the data of the two economies, the statistical comparison undertaken in this study shows that in general big business has played the major role in the development of the Korean economy while in Taiwan's economic development this role has been played by SMEs. Thus the statistical data also verifies the perceived dichotomy of these two economies.
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Large-eddy simulation (LES) has emerged as a promising tool for simulating turbulent flows in general and, in recent years,has also been applied to the particle-laden turbulence with some success (Kassinos et al., 2007). The motion of inertial particles is much more complicated than fluid elements, and therefore, LES of turbulent flow laden with inertial particles encounters new challenges. In the conventional LES, only large-scale eddies are explicitly resolved and the effects of unresolved, small or subgrid scale (SGS) eddies on the large-scale eddies are modeled. The SGS turbulent flow field is not available. The effects of SGS turbulent velocity field on particle motion have been studied by Wang and Squires (1996), Armenio et al. (1999), Yamamoto et al. (2001), Shotorban and Mashayek (2006a,b), Fede and Simonin (2006), Berrouk et al. (2007), Bini and Jones (2008), and Pozorski and Apte (2009), amongst others. One contemporary method to include the effects of SGS eddies on inertial particle motions is to introduce a stochastic differential equation (SDE), that is, a Langevin stochastic equation to model the SGS fluid velocity seen by inertial particles (Fede et al., 2006; Shotorban and Mashayek, 2006a; Shotorban and Mashayek, 2006b; Berrouk et al., 2007; Bini and Jones, 2008; Pozorski and Apte, 2009).However, the accuracy of such a Langevin equation model depends primarily on the prescription of the SGS fluid velocity autocorrelation time seen by an inertial particle or the inertial particle–SGS eddy interaction timescale (denoted by $\delt T_{Lp}$ and a second model constant in the diffusion term which controls the intensity of the random force received by an inertial particle (denoted by C_0, see Eq. (7)). From the theoretical point of view, dTLp differs significantly from the Lagrangian fluid velocity correlation time (Reeks, 1977; Wang and Stock, 1993), and this carries the essential nonlinearity in the statistical modeling of particle motion. dTLp and C0 may depend on the filter width and particle Stokes number even for a given turbulent flow. In previous studies, dTLp is modeled either by the fluid SGS Lagrangian timescale (Fede et al., 2006; Shotorban and Mashayek, 2006b; Pozorski and Apte, 2009; Bini and Jones, 2008) or by a simple extension of the timescale obtained from the full flow field (Berrouk et al., 2007). In this work, we shall study the subtle and on-monotonic dependence of $\delt T_{Lp}$ on the filter width and particle Stokes number using a flow field obtained from Direct Numerical Simulation (DNS). We then propose an empirical closure model for $\delta T_{Lp}$. Finally, the model is validated against LES of particle-laden turbulence in predicting single-particle statistics such as particle kinetic energy. As a first step, we consider the particle motion under the one-way coupling assumption in isotropic turbulent flow and neglect the gravitational settling effect. The one-way coupling assumption is only valid for low particle mass loading.
Human Resource Management in Multinational Enterprises: Evidence From a Late Industrializing Economy
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This paper examines the extent to which human resource management (HRM) practices in multinational enterprises (MNEs) from a small, late developing and highly globalized economy resemble their counterparts from larger, early industrializing countries. The paper draws on data from a large-scale representative survey of 260 MNEs in Ireland. The results demonstrate that there are significant differences between the HRM practices deployed in Irish-owned MNEs and that of their US counterparts but considerable similarity with UK firms. A key conclusion is that arguments in the literature regarding MNEs moving towards the adoption of global best practices, equating to the pursuance of an American model of HRM, were not obvious. The study found considerable variation from ‘US practices’ amongst indigenous Irish MNEs.
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The fundamental question in the transitional economies of the former Eastern Europe and Soviet Union has been whether privatisation and market liberalisation have had an effect on the performance of former state-owned enterprises. This study examines the effect of privatisation, capital market discipline, price liberalisation and international price exposure on the restructuring of large Russian enterprises. The performance indicators are sales, profitability, labour productivity and stock market valuations. The results do not show performance differences between state-owned and privatised enterprises. On the other hand, the expansion of the de novo private sector has been strong. New enterprises have significantly higher sales growth, profitability and labour productivity. However, the results indicate a diminishing effect of ownership. The international stock market listing has a significant positive effect on profitability, while the effect of domestic stock market listing is insignificant. The international price exposure has a significant positive increasing effect on profitability and labour productivity. International enterprises have higher profitability only when operating on price liberalised markets, however. The main results of the study are strong evidence on the positive effects of international linkages on the enterprise restructuring and the higher than expected role of new enterprises in the Russian economy.
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The Brazilian Amazon is one of the world’s largest tropical forests. It supplies more than 80 % of Brazil’s timber production and makes this nation the second largest producer of tropical wood. The forestry sector is of major importance in terms of economic production and employment creation. However, the Brazilian Amazon is also known for its high deforestation rate and for its rather unsustainably managed timber resources, a fact which puts in the balance the long-term future of the forestry sector in the region. Since the mid- 1990s, with strong support from World Wildlife Fund (WWF), the number of tropical forests certified by the Forest Stewardship Council (FSC) has significantly increased. This is especially true for projects sponsored by large scale companies. The number of community- based forest management projects has also increased. Certification of community-based forest enterprises (CFEs) was initially a goal for the sponsors and community members. Certification is viewed as a way to reach alternative timber markets. In Brazil, the state of Acre has the highest concentration of CFEs certified by FSC. Most of them have been implemented with the support of environmental NGOs and public funds. Environmental NGOs strongly defend the advantages of certification for communities; however, in reality, this option is not that advantageous. Despite all the efforts, the number of participants in each project remains low. Why is this occurring? In this paper, we analyze the underlying motives of a few individual’s participation in CFEs certification projects. We aim to present and discuss some factors that shape the success of CFEs and their later certification. The results are based on surveys conducted in two certified CFEs in the state of Acre.