Today, one of the most important phenomenons is the movement of Capital and the expansion of its investments, as well as the use of resources worldwide. The movement of Capital, is changing the local space and the ter...Today, one of the most important phenomenons is the movement of Capital and the expansion of its investments, as well as the use of resources worldwide. The movement of Capital, is changing the local space and the territories, because is not a homogeneous process; they are not in the same way and rhythm, this is because they don＇t get in the same way to global dynamics. The reorganization of the world, because the movements in Capital is a challenge, that is why, the analysis of regions demand new and different views, to boost regional development. We can tell that since a long time ago, had been developing theories and proposals not good enough, for this reason we must think to generate new proposals. The goal of this paper, is to expose the social and territorial changes in Silao and Romita Counties in the state of Guanajuato Mexico, as a result of the relocation of economic activities that lead us to start a new regional policy, that gives more satisfactory results and think about a regional policy that could reflex about territorial development focuses, specially for a public policy.展开更多
The brushless DC motor can be used in the marine electric propulsion system for its excellent control characteristics and large thrust. In order to estimate the operating performances of the brushless DC motor for the...The brushless DC motor can be used in the marine electric propulsion system for its excellent control characteristics and large thrust. In order to estimate the operating performances of the brushless DC motor for the high-power shipping during the design stage, the steady-state analysis is as important as the dynamic analysis generally. A mathematical model of the brushless DC propulsion motor is established according to the state-space method for the dynamic and steady-state performance analysis. The state-space mathematical model is a set of linear differential equations, so the steady-state currents of the armature windings can be gained directly by the symmetrical boundary conditions and the eigenvalues of the system matrix. The steady-state simulation results are compared with the dynamic ones to validate the correctness of this eigenvector method.展开更多
This work analyzes a novel MEMS-based architecture of submillimeter size thruster for the propulsion of small spacecrafts,addressing its preliminary characterization of performance.The architecture of microthruster co...This work analyzes a novel MEMS-based architecture of submillimeter size thruster for the propulsion of small spacecrafts,addressing its preliminary characterization of performance.The architecture of microthruster comprises a setup of miniaturized channels surrounding the solid-propellant reservoir filled up with a high-energetic polymer.These channels guide the hot gases from the combustion region towards the nozzle entrance located at the opposite side of the thruster.Numerical simulations of the transient response of the combustion gases and wafer heating in thruster firings have been conducted with FLUENT under a multiphysics modelling that fully couples the gas and solid parts involved.The approach includes the gas-wafer and gas-polymer thermal exchange,burnback of the polymer with a simplified non-reacting gas pyrolysis model at its front,and a slip-model inside the nozzle portion to incorporate the effect of gas-surface and rarefaction onto the gas expansion.Besides,accurate characterization of thruster operation requires the inclusion of the receding front of the polymer and heat transfer in the moving gas-solid interfaces.The study stresses the improvement attained in thermal management by the inclusion of lateral micro-channels in the device.In particular,the temperature maps reveal the significant dependence of the thermal loss on the instantaneous surface of the reservoir wall exposed to the heat flux of hot gases.Specifically,the simulations stress the benefit of implementing such a pattern of micro-channels connecting the exit of the combustion reservoir with the nozzle.The results prove that hot gases flowing along the micro-channels exert a sealing action upon the heat flux at the reservoir wall and partly mitigate the overall thermal loss at the inner-wall vicinity during the burnback.The analysis shows that propellant decomposition rate is accelerated due to surface preheating and it suggests that a delay of the flame extinction into the reservoir is possible.The simulated operation of the thruster concept shows encouraging performance.展开更多
文摘Today, one of the most important phenomenons is the movement of Capital and the expansion of its investments, as well as the use of resources worldwide. The movement of Capital, is changing the local space and the territories, because is not a homogeneous process; they are not in the same way and rhythm, this is because they don＇t get in the same way to global dynamics. The reorganization of the world, because the movements in Capital is a challenge, that is why, the analysis of regions demand new and different views, to boost regional development. We can tell that since a long time ago, had been developing theories and proposals not good enough, for this reason we must think to generate new proposals. The goal of this paper, is to expose the social and territorial changes in Silao and Romita Counties in the state of Guanajuato Mexico, as a result of the relocation of economic activities that lead us to start a new regional policy, that gives more satisfactory results and think about a regional policy that could reflex about territorial development focuses, specially for a public policy.
文摘The brushless DC motor can be used in the marine electric propulsion system for its excellent control characteristics and large thrust. In order to estimate the operating performances of the brushless DC motor for the high-power shipping during the design stage, the steady-state analysis is as important as the dynamic analysis generally. A mathematical model of the brushless DC propulsion motor is established according to the state-space method for the dynamic and steady-state performance analysis. The state-space mathematical model is a set of linear differential equations, so the steady-state currents of the armature windings can be gained directly by the symmetrical boundary conditions and the eigenvalues of the system matrix. The steady-state simulation results are compared with the dynamic ones to validate the correctness of this eigenvector method.
基金funded by the Spanish Ministry of Defence as part of the micropropulsion activities in the Small Satellites Programme
文摘This work analyzes a novel MEMS-based architecture of submillimeter size thruster for the propulsion of small spacecrafts,addressing its preliminary characterization of performance.The architecture of microthruster comprises a setup of miniaturized channels surrounding the solid-propellant reservoir filled up with a high-energetic polymer.These channels guide the hot gases from the combustion region towards the nozzle entrance located at the opposite side of the thruster.Numerical simulations of the transient response of the combustion gases and wafer heating in thruster firings have been conducted with FLUENT under a multiphysics modelling that fully couples the gas and solid parts involved.The approach includes the gas-wafer and gas-polymer thermal exchange,burnback of the polymer with a simplified non-reacting gas pyrolysis model at its front,and a slip-model inside the nozzle portion to incorporate the effect of gas-surface and rarefaction onto the gas expansion.Besides,accurate characterization of thruster operation requires the inclusion of the receding front of the polymer and heat transfer in the moving gas-solid interfaces.The study stresses the improvement attained in thermal management by the inclusion of lateral micro-channels in the device.In particular,the temperature maps reveal the significant dependence of the thermal loss on the instantaneous surface of the reservoir wall exposed to the heat flux of hot gases.Specifically,the simulations stress the benefit of implementing such a pattern of micro-channels connecting the exit of the combustion reservoir with the nozzle.The results prove that hot gases flowing along the micro-channels exert a sealing action upon the heat flux at the reservoir wall and partly mitigate the overall thermal loss at the inner-wall vicinity during the burnback.The analysis shows that propellant decomposition rate is accelerated due to surface preheating and it suggests that a delay of the flame extinction into the reservoir is possible.The simulated operation of the thruster concept shows encouraging performance.
