6,628 research outputs found
Foreign direct investment and the SME sector
Purpose: Although foreign direct investment (FDI) and entrepreneurship are potential routes to recovery (Girma and Wakelin, 2001; Lyon et al., 2002), existing literature is divided on the relationship between the two. This study examines the influence of foreign investment on the local SME sector after the 2008 financial crisis. Design/methodology/approach: Local authority district data from Great Britain is used to examine the influence of foreign firm employment on the size of the local SME sector as a proportion of all firms, and foreign firm influence on firm births in the locality. In order to control for local geographical, infrastructural, and economic conditions regression analysis is used to examine the relationship between foreign business employment and indigenous business activities. Findings: The potential for technological spillovers and spinout activities appears to dominate with firm birth rates higher where there is greater foreign firm employment. However, there is also evidence of crowding out in relation to the existing SME sector, which is found to be reduced in size where foreign influence through employment is greater.
Research Implications: The results here indicating a complementarity relationship between foreign influence on employment and firm births is important for policy makers looking to revive struggling local economies. However, the relevant support needs to be in place to maximise the benefit from the supply of new entrepreneurs generated. Originality/value: Unlike many other studies the relationship between the SME sector, firm births and foreign influence is considered at a local level and where economic conditions are more uncertain and economic recovery is less taken for granted. A better understanding of the relationship allows more appropriate policy to be developed in order to aid local economies to recover
Spectral methods for modeling supersonic chemically reacting flow fields
A numerical algorithm was developed for solving the equations describing chemically reacting supersonic flows. The algorithm employs a two-stage Runge-Kutta method for integrating the equations in time and a Chebyshev spectral method for integrating the equations in space. The accuracy and efficiency of the technique were assessed by comparison with an existing implicit finite-difference procedure for modeling chemically reacting flows. The comparison showed that the procedure presented yields equivalent accuracy on much coarser grids as compared to the finite-difference procedure with resultant significant gains in computational efficiency
Foreign business ownership and domestic entrepreneurial exports
Purpose: There has been considerable debate about the impact that Foreign Direct Investment (FDI) has upon home grown enterprise (Pathak et al., 2015). This study examines how foreign business ownership at the local level affects the decision of individual UK entrepreneurs to export their production. Design/methodology/approach: The Global Entrepreneurship Monitor (GEM) data and ONS foreign firm employment data are used within this study. In order to control for entrepreneurial and firm characteristics, a multivariate approach is adopted with logit, ordered logit and multinominal logit regressions utilised. Findings: It is found that the influence of foreign firms, as captured by their share of local employment, has a negative influence on domestic entrepreneurs’ probability of exporting, but has no significant effect on the intensity of these export activities. Research Implications: The results suggest that local economies may not only become highly reliant on foreign employers, but also on local demand for domestic production. This means actions might be required to reduce this over-reliance to ensure the development of resilient local economies. Originality/value: Unlike many other studies the relationship between the SME exports and foreign influence is considered at a local level. With the current UK government seeking to increase UK firms’ exports substantially, understanding this relationship is of key importance to policy makers
Switchable opening and closing of a liquid marble via ultrasonic levitation
Liquid marbles have promising applications in the field of microreactors, where the opening and closing of their surfaces plays a central role. We have levitated liquid water marbles using an acoustic levitator and, thereby, achieved the manipulation of the particle shell in a controlled manner. Upon increasing the sound intensity, the stable levitated liquid marble changes from a quasi-sphere to a flattened ellipsoid. Interestingly, a cavity on the particle shell can be produced on the polar areas, which can be completely healed when decreasing the sound intensity, allowing it to serve as a microreactor. The integral of the acoustic radiation pressure on the part of the particle surface protruding into air is responsible for particle migration from the center of the liquid marble to the edge. Our results demonstrate that the opening and closing of the liquid marble particle shell can be conveniently achieved via acoustic levitation, opening up a new possibility to manipulate liquid marbles coated with non-ferromagnetic particles
A comparison of assimilation results from the ensemble Kalman Filter and a reduced-rank extended Kalman Filter
International audienceThe goal of this study is to compare the performances of the ensemble Kalman filter and a reduced-rank extended Kalman filter when applied to different dynamic regimes. Data assimilation experiments are performed using an eddy-resolving quasi-geostrophic model of the wind-driven ocean circulation. By changing eddy viscosity, this model exhibits two qualitatively distinct behaviors: strongly chaotic for the low viscosity case and quasi-periodic for the high viscosity case. In the reduced-rank extended Kalman filter algorithm, the model is linearized with respect to the time-mean from a long model run without assimilation, a reduced state space is obtained from a small number (100 for the low viscosity case and 20 for the high viscosity case) of leading empirical orthogonal functions (EOFs) derived from the long model run without assimilation. Corrections to the forecasts are only made in the reduced state space at the analysis time, and it is assumed that a steady state filter exists so that a faster filter algorithm is obtained. The ensemble Kalman filter is based on estimating the state-dependent forecast error statistics using Monte Carlo methods. The ensemble Kalman filter is computationally more expensive than the reduced-rank extended Kalman filter.The results show that for strongly nonlinear case, chaotic regime, about 32 ensemble members are sufficient to accurately describe the non-stationary, inhomogeneous, and anisotropic structure of the forecast error covariance and the performance of the reduced-rank extended Kalman filter is very similar to simple optimal interpolation and the ensemble Kalman filter greatly outperforms the reduced-rank extended Kalman filter. For the high viscosity case, both the reduced-rank extended Kalman filter and the ensemble Kalman filter are able to significantly reduce the analysis error and their performances are similar. For the high viscosity case, the model has three preferred regimes, each with distinct energy levels. Therefore, the probability density of the system has a multi-modal distribution and the error of the ensemble mean for the ensemble Kalman filter using larger ensembles can be larger than with smaller ensembles
Binding energy of shallow donors in a quantum well in the presence of a tilted magnetic field
We present results of variational calculations of the binding energy of a
neutral donor in a quantum well in the presence of a magnetic field tilted
relative to the QW plane. Assuming that the donor is located in the center of
the QW, we perform calculations for parameters typical of a II-VI wide-gap
semiconductor heterostructure, using as an example the case of a rectangular
CdTe quantum well with CdMgTe barriers. We present the dependence of the
binding energy of a neutral donor on the tilt angle and on the magnitude of the
applied magnetic filed. As a key result, we show that measurement of the
binding energy of a donor at two angles of the magnetic field with respect to
the quantum well plane can be used to unambiguously determined the conduction
band offset of the materials building up heterostructure.Comment: 6 pages, 5 figure
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Analysis of sensitivity and optimization for mistuned bladed disk forced response using high-fidelity models
An effective method is developed for efficient calculations of the sensitivity of the maximum forced response levels for mistuned bladed disks with respect to blade frequency mistuning. The expressions for 1st and 2nd order sensitivity coefficients are derived in an analytical form which provides high accuracy and computational efficiency. Then, the optimization methods are used for searching the best and worst mistuning patterns of bladed disks. Two major types of the mistuning optimization problems are considered: (i) a continuous optimization problem when the blade mistuning can take any values from a prescribed range and (ii) a combinatorial optimization problem, when the set of mistuned blades is given and the optimization can be achieved by blade re-arrangement in a disk. For the first type of the optimization problem a set of sensitivity-based optimization algorithms is applied and for the second type a variant of a genetic algorithm is developed. The analysis of mistuning sensitivity coefficients and results of optimization searching are shown on an example of a realistic turbine bladed disk
Mathematics simulation and experiments of continuous casting with strip feeding in mold
Steel strip feeding technology can reduce the degree of superheat of the molten steel, change the solidification order of the molten steel; raise the equiaxed crystal rate of the slab and improve the continuous casting quality. The paper establishes the mathematical model of heat transfer and temperature field of casting billet of steel strip feeding in continuous casting mold. Results show that if Plate Billet is 1 000 mm × 220 mm and the steel strip is 100 mm × 3 mm, feeding position of parallel is 250 mm from the narrow side. When the feeding speed is 3,6 m/min, the superheat degree can be reduced by 5 °C, and the solidification length can be reduced by 2,9 m. When the feeding speed is 6 m/min, the superheat degree can be reduced by about 9 °C, and the solidification length can be reduced by 3,7 m. The results of the test in a steel plant are in good agreement with the experimental results
Barkhausen effect in steels and its dependence on surface condition
Micromagnetic Barkhausen signals from magnetic materials originate from the discontinuous changes in magnetization under the action of a changing applied magnetic field.Barkhausen emissions that are detected by a sense coil come predominantly from a surface layer. In iron based materials this layer is about 500 ÎĽm thick. The Barkhausen signal is affected by changes in material microstructure and the presence of residual stress, since these affect the dynamics of domain wall motion. The selective attenuation of high frequency components of the Barkhausen signal due to eddy currents in electrically conducting materials is used to evaluate changes in material condition at different depths inside the material.Barkhausen measurements on specimens subjected to different thermal treatment during surface conditioning procedures are presented. Also presented for comparison are analysis of the material condition using x-ray diffraction for assessment of residual stress, and microhardness measurements which evaluate the surface microstructure condition. The results show that Barkhausen emissions can be utilized to evaluate changes in the surface condition of materials
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