Magnetic field control of cryogenic heat pipes
This paper deals with cryogenic heat pipes controlled by static magnetic field. Heat pipe is an equipment which allows a very effective heat transport. They are commonly used in electronic devices and in many other types of equipment as well. Some applications require heat flow controllability. For that purpose heat pipes are modified to many different constructions with variable heat conductance. Magnetic field control of heat transport is a new solution researched in a few laboratories in the world and still not practically applicated. According to the results of some experiments, implemented in our laboratory and several another laboratories, it seems to be possible to control heat transport in chosen types of heat pipes by a static magnetic field. The cryogenic heat pipe filled with pure oxygen has been made for that purpose and a testing device has been arranged as well. We have found out that the heat transport efficiency of the heat pipe has rapidly decreased by a magnetic field exposure. Some interesting results of our experiments will be presented in this paper.
Control of heat transport in heat pipes by magnetic fields
We have observed that gas flow can be blocked or disturbed by magnetic fields. To explain this phenomenon, we developed a model called a ‘‘magnetic curtain’’ based on the paramagnetic properties of the oxygen molecule. In this paper, we applied this phenomenon to the control of heat transport in heat pipes. We used a heat pipe 20 mm in diameter and 500 mm in length packed with oxygen as a working fluid. We positioned this device vertically in an airgap 70‐mm wide between the poles of electromagnet with 240 mm in diameter, in the direction perpendicular to the axis of the magnetic poles. The top side of the heat pipe was chilled with liquid nitrogen (77 K), and the lower side of the heat pipe was exposed to the room temperature (290 K). The efficiency of heat transport was measured by monitoring the change of the temperature at seven points inside and outside of the heat pipe in response to the step change of the top temperature from 290 to 77 K. When the middle part of the heat pipe was exposed to magneti...
Foundations of Despotism: Peasants, the Trujillo Regime, and Modernity in Dominican History
This book explores the history of the Dominican Republic as it evolved from the first European colony in the Americas into a modern nation under the rule of Rafael Trujillo. It investigates the social foundations of Trujillo's exceptionally enduring and brutal dictatorship (1930-1961) and, more broadly, the way power is sustained in such non-democratic regimes. The author reveals how the seemingly unilateral imposition of power by Trujillo in fact depended on the regime's mediation of profound social and economic transformations, especially through agrarian policies that assisted the nation's large independent peasantry. By promoting an alternative modernity that sustained peasants' free access to land during a period of economic growth, the regime secured peasant support as well as backing from certain elite sectors. This book thus elucidates for the first time the hidden foundations of the Trujillo regime.