A mathematical model is developed for simulating the heat transferring behavior in a direct metal laser sintering process. The model considers the thermal phenomena involved in the process, including conduction, radia...A mathematical model is developed for simulating the heat transferring behavior in a direct metal laser sintering process. The model considers the thermal phenomena involved in the process, including conduction, radiation, and convection. A formula for the calculation of the heat conductivity of a sintering system containing solid phase, liquid phase, and gas phase is given. Due to the continuous movement of the laser beam, a local coordinate system centered on the laser beam is used to simplify the analytical calculation. Assuming that it is approximately a Gaussian laser beam, the heat conduction equation is resolved based on the assumption of the thermal insulating boundary conditions and the fixed thermal physical parameters. The FORTRAN language is employed to compile the program to simulate the temperature field in the direct copper powder sintering process. It shows a good agreement with the preliminary experimental results.[KH3/4D]展开更多
[Obective] This study amied to evaluate the direct usage value of Liangzi Lake, like plants and animal resources and water storage value. [Method] It was measured through the market value method. The physical environm...[Obective] This study amied to evaluate the direct usage value of Liangzi Lake, like plants and animal resources and water storage value. [Method] It was measured through the market value method. The physical environment was introduced and the productivity of the lake was investigated both through the literature materials and the investigations. The market value method was clarified in this paper as well as its operation process and the application fields. [Result] Based on the introduction of the current situation in Liangzi Lake, the direct usage value was estimated as 1.32 billion Yuan/year. Plant resources value was 318 million Yuan/year; animal resources value was 675 million Yuan/year; and water storage value was 325 million Yuan/year for the three parts. [Conclusion] This paper will attract more attention to the emphasis of the reasonable development of nature sources.展开更多
A high-performance digital servo system built on the platform of a field programmable gate array (FPGA),a fully digitized hardware design scheme of a direct torque control (DTC) and a low speed permanent magnet synchr...A high-performance digital servo system built on the platform of a field programmable gate array (FPGA),a fully digitized hardware design scheme of a direct torque control (DTC) and a low speed permanent magnet synchronous motor (PMSM) is proposed. The DTC strategy of PMSM is described with Verilog hardware description language and is employed on-chip FPGA in accordance with the electronic design automation design methodology. Due to large torque ripples in low speed PMSM,the hysteresis controller in a conventional PMSM DTC was replaced by a fuzzy controller. This FPGA scheme integrates the direct torque controller strategy,the time speed measurement algorithm,the fuzzy regulating technique and the space vector pulse width modulation principle. Experimental results indicate the fuzzy controller can provide a controllable speed at 20 r min-1 and torque at 330 N m with satisfactory dynamic and static performance. Furthermore,the results show that this new control strategy decreases the torque ripple drastically and enhances control performance.展开更多
This paper aims to review and analyze the literature on the expansion of Chinese firms to Latin America. In order to achieve this objective, it first reviews the literature on the internationalization of Chinese MNCs,...This paper aims to review and analyze the literature on the expansion of Chinese firms to Latin America. In order to achieve this objective, it first reviews the literature on the internationalization of Chinese MNCs, the theoretical frameworks discussed in the literature and the principal features of companies from China. Second, it describes the economic and political relations between the countries, specifically the threats and opportunities for Latin America and the trade and investment trends. The review shows that the majority of the current literature on Chinese MNCs has a focus on their expansion to developed countries, on the conceptual framework needed to understand this expansion, and on the competition for foreign investments from developed countries. As a result, the analysis makes evident that research gaps seem to exist in the following areas： （1） the relative value of Chinese companies＇ existing advantages, （2） the sustainability of these advantages once the lead, probably given by OEMs or JVs, had been exhausted, （3） research works based on quantitative and comparative data, （4） the motives for FDI, （5） the entry mode, configuration, control and strategy of Chinese companies investing in Latin America, and （6） the potential opportunities presented to European companies operating in Latin America.展开更多
After reviewing three different definitions of mode field diameter of single-mode fibers, coupled efficiency calculation methods associated with lateral offset, longitude separation and wavelength, the effects produce...After reviewing three different definitions of mode field diameter of single-mode fibers, coupled efficiency calculation methods associated with lateral offset, longitude separation and wavelength, the effects produced by them, and the influences of splicing defects were discussed in detail. The regularities of the effects were studied according to the first order derivation of couple efficiency formula, and a simplified formula for couple efficiency calculation was presented under the circumstance of slight misalignment, with respect to wavelength, 2, and in a good agreement with the theoretical model. The simplified formula provides a new but simple approach to evaluate wavelength dependent couple efficiency of single-mode fibers. Theoretical analyses and numerical calculations show that, when those defects exist, the wavelength produces additional effects on the couple loss that growth of wavelength causes an increase on the couple efficiency for the lateral offset or longitude separation whereas lessens the couple efficiency due to angular misalignment or mode fields mismatching, and that the wavelength degrades the couple efficiency distinctly when λ≥2.5 μm whereas it distorts the couple slightly in range of λ≤2λ≤2 μm.展开更多
Since the early 1990s, China has become the largest destination of Japanese foreign direct investment （FDI）. Observing this trend, the authors analyzed whether Japanese FDI did promote exports from China to the rest...Since the early 1990s, China has become the largest destination of Japanese foreign direct investment （FDI）. Observing this trend, the authors analyzed whether Japanese FDI did promote exports from China to the rest of the world, and more importantly, whether this is a strategy adopted by Japanese multinationals to penetrate not only the Chinese market but also the global market. This analysis takes into account not only the direct effects of FDI on exports, but also the indirect effects, by examining the mediating role of export oriented Japanese FDI in China from 1998 to 2007 through panel analysis. The study contributes to the conceptual framework of indirect relationship among the macroeconomic variables, FDI and exports provides some insights into the strategy of export oriented Japanese FDI in creating a win-win platform for Japan and China.展开更多
Globalization creates investment opportunities for enterprises worldwide. FDI is one of the traditional options to expand into international markets. According to Dunning＇s ownership, location, and internationalizati...Globalization creates investment opportunities for enterprises worldwide. FDI is one of the traditional options to expand into international markets. According to Dunning＇s ownership, location, and internationalization paradigm FDI location is driven by the search for markets, resources, efficiency, and strategic assets. Corruption can be considered as a significant factor of the attractiveness of a location and can affect also other OLI conditions. Most of the theoretical literature as well as case study and microeconomic evidence support the notion that corruption negatively impacts inward FDI flows and growth. However the macroeconomic evidence is not so unambiguous Some macro-studies do not detect any significant negative relationship between corruption and FDI. The aim of the paper is to analyze the relationship mechanism between corruption and FDI and to evaluate the impact of the host country corruption on inward FDI flows. The results of the empiric analysis presented in the paper provide evidence of the significant negative impact of host country corruption on inward FDI. One of the main benefits from the decrease of corruption level is quantitatively valued as an additional inward flow of the foreign capital in the economy. The econometric analysis is based on panel dataset that includes data for 178 economies during the period of 2004 to 2009. The Transparency International Corruption Perceptions Index is used as a proxy for host country corruption level展开更多
Internationalization of company activities is the necessity of the development for majority of entrepreneurial subjects in the Czech Republic. Internationalization of entrepreneurial activities becomes a tool of busin...Internationalization of company activities is the necessity of the development for majority of entrepreneurial subjects in the Czech Republic. Internationalization of entrepreneurial activities becomes a tool of business competitiveness. Selecting the right foreign entry mode is an important decision, which demands a lot of resources and thorough planning. The factors influencing company＇s choice of entry mode are divided into two main groups subsuming--external and internal factors. External factors consist of determinants regarding the company＇s environment while the intemal ones are determined by the company＇s specific factors. The opening of new markets such as in the Czech Republic has created the potential for small and medium-size enterprise （SME） expansion and investment. The objective of this paper is to present an application of the entry modes of the selected Czech entrepreneurial subjects. The companies included in the study are those that have undertaken internationalization activities and are incorporated in the Czech Republic. There were a total of 297 enterprises that participated in the research. The research method was an oral questioning and the main instrument was a questionnaire. A relatively low degree of Czech companies that have undergone intemationalization has resulted in the dominance of the least advanced forms of internationalization expansion, mainly exports with a small share of more advanced forms of foreign direct investments and a very low level of forms of international cooperation. Czech companies are in decision about the choosing the foreign entry mode influenced by the many factors. The greatest influence on the choice of foreign entry mode has entry mode variables. Entry mode variables constitute variables assessment characteristics of particular entry mode.展开更多
In order to get thermal flow field of direct air-cooled system,the hot water was supplied to the model of direct air-cooled condenser(ACC). The particle image velocimetery (PIV) experiments were carried out to get the...In order to get thermal flow field of direct air-cooled system,the hot water was supplied to the model of direct air-cooled condenser(ACC). The particle image velocimetery (PIV) experiments were carried out to get thermal flow field of a ACC under different conditions in low velocity wind tunnel,at the same time,the recirculation ratio at cooling tower was measured,so the relationship between flow field characteristics and recirculation ratio of cooling tower can be discussed. From the results we can see that the flow field configuration around cooling tower has great effects on average recirculation ratio under cooling tower. The eddy formed around cooling tower is a key reason that recirculation produces. The eddy intensity relates to velocity magnitude and direction angle,and the configuration of eddy lies on the geometry size of cooling tower. So changing the flow field configuration around cooling tower reasonably can decrease recirculation ratio under cooling tower,and heat dispel effect of ACC can also be improved.展开更多
There must be electromagnetic fields created during high-energy heavy-ion collisions.Although the electromagnetic field may become weak with the evolution of the quark-gluon plasma(QGP),compared to the energy scales o...There must be electromagnetic fields created during high-energy heavy-ion collisions.Although the electromagnetic field may become weak with the evolution of the quark-gluon plasma(QGP),compared to the energy scales of the strong interaction,they are potentially important to some electromagnetic probes.In this work,we propose the coupled effect of the weak magnetic field and the longitudinal dynamics of the background medium for the first time.We demonstrate that the induced photon spectrum can be highly azimuthally anisotropic when the quarkgluon plasma is in the presence of a weak external magnetic field.On the other hand,the weak magnetic photon emission from quark-gluon plasma only leads to a small correction to the photon production rate.After hydrodynamic evolution with a tilted fireball configuration,the experimentally measured direct photon elliptic flow is well reproduced.Meanwhile,the used time-averaged magnetic field in the hydrodynamic stage is found no larger than a few percent of the pion mass square.展开更多
文摘A mathematical model is developed for simulating the heat transferring behavior in a direct metal laser sintering process. The model considers the thermal phenomena involved in the process, including conduction, radiation, and convection. A formula for the calculation of the heat conductivity of a sintering system containing solid phase, liquid phase, and gas phase is given. Due to the continuous movement of the laser beam, a local coordinate system centered on the laser beam is used to simplify the analytical calculation. Assuming that it is approximately a Gaussian laser beam, the heat conduction equation is resolved based on the assumption of the thermal insulating boundary conditions and the fixed thermal physical parameters. The FORTRAN language is employed to compile the program to simulate the temperature field in the direct copper powder sintering process. It shows a good agreement with the preliminary experimental results.[KH3/4D]
文摘[Obective] This study amied to evaluate the direct usage value of Liangzi Lake, like plants and animal resources and water storage value. [Method] It was measured through the market value method. The physical environment was introduced and the productivity of the lake was investigated both through the literature materials and the investigations. The market value method was clarified in this paper as well as its operation process and the application fields. [Result] Based on the introduction of the current situation in Liangzi Lake, the direct usage value was estimated as 1.32 billion Yuan/year. Plant resources value was 318 million Yuan/year; animal resources value was 675 million Yuan/year; and water storage value was 325 million Yuan/year for the three parts. [Conclusion] This paper will attract more attention to the emphasis of the reasonable development of nature sources.
基金the Natural Science Foundation of Hubei Province (No.2005ABA301)
文摘A high-performance digital servo system built on the platform of a field programmable gate array (FPGA),a fully digitized hardware design scheme of a direct torque control (DTC) and a low speed permanent magnet synchronous motor (PMSM) is proposed. The DTC strategy of PMSM is described with Verilog hardware description language and is employed on-chip FPGA in accordance with the electronic design automation design methodology. Due to large torque ripples in low speed PMSM,the hysteresis controller in a conventional PMSM DTC was replaced by a fuzzy controller. This FPGA scheme integrates the direct torque controller strategy,the time speed measurement algorithm,the fuzzy regulating technique and the space vector pulse width modulation principle. Experimental results indicate the fuzzy controller can provide a controllable speed at 20 r min-1 and torque at 330 N m with satisfactory dynamic and static performance. Furthermore,the results show that this new control strategy decreases the torque ripple drastically and enhances control performance.
文摘This paper aims to review and analyze the literature on the expansion of Chinese firms to Latin America. In order to achieve this objective, it first reviews the literature on the internationalization of Chinese MNCs, the theoretical frameworks discussed in the literature and the principal features of companies from China. Second, it describes the economic and political relations between the countries, specifically the threats and opportunities for Latin America and the trade and investment trends. The review shows that the majority of the current literature on Chinese MNCs has a focus on their expansion to developed countries, on the conceptual framework needed to understand this expansion, and on the competition for foreign investments from developed countries. As a result, the analysis makes evident that research gaps seem to exist in the following areas： （1） the relative value of Chinese companies＇ existing advantages, （2） the sustainability of these advantages once the lead, probably given by OEMs or JVs, had been exhausted, （3） research works based on quantitative and comparative data, （4） the motives for FDI, （5） the entry mode, configuration, control and strategy of Chinese companies investing in Latin America, and （6） the potential opportunities presented to European companies operating in Latin America.
基金Projects（51005074, 91123035） supported by the National Natural Science Foundation of China Project（201021200077） supported by the Frontier Research Program of Central South University, China
文摘After reviewing three different definitions of mode field diameter of single-mode fibers, coupled efficiency calculation methods associated with lateral offset, longitude separation and wavelength, the effects produced by them, and the influences of splicing defects were discussed in detail. The regularities of the effects were studied according to the first order derivation of couple efficiency formula, and a simplified formula for couple efficiency calculation was presented under the circumstance of slight misalignment, with respect to wavelength, 2, and in a good agreement with the theoretical model. The simplified formula provides a new but simple approach to evaluate wavelength dependent couple efficiency of single-mode fibers. Theoretical analyses and numerical calculations show that, when those defects exist, the wavelength produces additional effects on the couple loss that growth of wavelength causes an increase on the couple efficiency for the lateral offset or longitude separation whereas lessens the couple efficiency due to angular misalignment or mode fields mismatching, and that the wavelength degrades the couple efficiency distinctly when λ≥2.5 μm whereas it distorts the couple slightly in range of λ≤2λ≤2 μm.
文摘Since the early 1990s, China has become the largest destination of Japanese foreign direct investment （FDI）. Observing this trend, the authors analyzed whether Japanese FDI did promote exports from China to the rest of the world, and more importantly, whether this is a strategy adopted by Japanese multinationals to penetrate not only the Chinese market but also the global market. This analysis takes into account not only the direct effects of FDI on exports, but also the indirect effects, by examining the mediating role of export oriented Japanese FDI in China from 1998 to 2007 through panel analysis. The study contributes to the conceptual framework of indirect relationship among the macroeconomic variables, FDI and exports provides some insights into the strategy of export oriented Japanese FDI in creating a win-win platform for Japan and China.
文摘Globalization creates investment opportunities for enterprises worldwide. FDI is one of the traditional options to expand into international markets. According to Dunning＇s ownership, location, and internationalization paradigm FDI location is driven by the search for markets, resources, efficiency, and strategic assets. Corruption can be considered as a significant factor of the attractiveness of a location and can affect also other OLI conditions. Most of the theoretical literature as well as case study and microeconomic evidence support the notion that corruption negatively impacts inward FDI flows and growth. However the macroeconomic evidence is not so unambiguous Some macro-studies do not detect any significant negative relationship between corruption and FDI. The aim of the paper is to analyze the relationship mechanism between corruption and FDI and to evaluate the impact of the host country corruption on inward FDI flows. The results of the empiric analysis presented in the paper provide evidence of the significant negative impact of host country corruption on inward FDI. One of the main benefits from the decrease of corruption level is quantitatively valued as an additional inward flow of the foreign capital in the economy. The econometric analysis is based on panel dataset that includes data for 178 economies during the period of 2004 to 2009. The Transparency International Corruption Perceptions Index is used as a proxy for host country corruption level
文摘Internationalization of company activities is the necessity of the development for majority of entrepreneurial subjects in the Czech Republic. Internationalization of entrepreneurial activities becomes a tool of business competitiveness. Selecting the right foreign entry mode is an important decision, which demands a lot of resources and thorough planning. The factors influencing company＇s choice of entry mode are divided into two main groups subsuming--external and internal factors. External factors consist of determinants regarding the company＇s environment while the intemal ones are determined by the company＇s specific factors. The opening of new markets such as in the Czech Republic has created the potential for small and medium-size enterprise （SME） expansion and investment. The objective of this paper is to present an application of the entry modes of the selected Czech entrepreneurial subjects. The companies included in the study are those that have undertaken internationalization activities and are incorporated in the Czech Republic. There were a total of 297 enterprises that participated in the research. The research method was an oral questioning and the main instrument was a questionnaire. A relatively low degree of Czech companies that have undergone intemationalization has resulted in the dominance of the least advanced forms of internationalization expansion, mainly exports with a small share of more advanced forms of foreign direct investments and a very low level of forms of international cooperation. Czech companies are in decision about the choosing the foreign entry mode influenced by the many factors. The greatest influence on the choice of foreign entry mode has entry mode variables. Entry mode variables constitute variables assessment characteristics of particular entry mode.
文摘In order to get thermal flow field of direct air-cooled system,the hot water was supplied to the model of direct air-cooled condenser(ACC). The particle image velocimetery (PIV) experiments were carried out to get thermal flow field of a ACC under different conditions in low velocity wind tunnel,at the same time,the recirculation ratio at cooling tower was measured,so the relationship between flow field characteristics and recirculation ratio of cooling tower can be discussed. From the results we can see that the flow field configuration around cooling tower has great effects on average recirculation ratio under cooling tower. The eddy formed around cooling tower is a key reason that recirculation produces. The eddy intensity relates to velocity magnitude and direction angle,and the configuration of eddy lies on the geometry size of cooling tower. So changing the flow field configuration around cooling tower reasonably can decrease recirculation ratio under cooling tower,and heat dispel effect of ACC can also be improved.
文摘There must be electromagnetic fields created during high-energy heavy-ion collisions.Although the electromagnetic field may become weak with the evolution of the quark-gluon plasma(QGP),compared to the energy scales of the strong interaction,they are potentially important to some electromagnetic probes.In this work,we propose the coupled effect of the weak magnetic field and the longitudinal dynamics of the background medium for the first time.We demonstrate that the induced photon spectrum can be highly azimuthally anisotropic when the quarkgluon plasma is in the presence of a weak external magnetic field.On the other hand,the weak magnetic photon emission from quark-gluon plasma only leads to a small correction to the photon production rate.After hydrodynamic evolution with a tilted fireball configuration,the experimentally measured direct photon elliptic flow is well reproduced.Meanwhile,the used time-averaged magnetic field in the hydrodynamic stage is found no larger than a few percent of the pion mass square.
