Thermal analysis of piezoelectric actuators for active cooling of RF phased array radars
RF communications and radar systems present an extreme thermal management challenge. These systems are comprised of tightly packaged high wattage components requiring a controlled temperature to meet performance and reliability parameters. One approach being pursued to meet this thermal challenge is embedding piezoelectric actuators within the electronics to create synthetic air jet drives for localized cooling. U.S. Army AMRDEC is developing and testing actuator test beds to mature the concepts and develop practical solutions. This investigation attempts to model these actuators in a CFD thermal analysis program, verify the results of the models with the current test beds, and then insert the model in conceptual designs of phased array antennas. The goal of the investigation is to gain insight into the practical application of a maturing thermal management concept in a real world application. These cooling devices have achieved over 2.5 W/cm2 cooling capacity in a 1.3 cm3 package.
Integrated PCB active cooling with piezoelectric actuator
Thermal management is challenging in RF communication and radar systems that require high-power levels for operation and reliability as well as small footprints to control intrinsic losses and meet design constraints. An interesting approach uses discrete, in-situ fluid handling and embedded synthetic jet drivers to enhance local cooling at the component. In this approach, fluid cavities and actuators are integrated into the PCB near the component. Magnetic and piezoelectric actuators have proven effective in other less-demanding applications. The challenge to adapting from magnetic to piezoelectric actuators is to achieve high flowrates because piezo-actuators have lower displacement and higher frequencies. This investigation explores frequency and displacement effects on cooling rates for piezo-actuators embedded in PCB. Further concept development includes integration with thermal ground planes.
Relationship between level of internet addiction and time management skills among nursing students.
PURPOSE
This study investigated nursing students' levels of internet addiction (IA) and time management (TM) skills.


DESIGN AND METHODS
This cross-sectional descriptive study was conducted with 400 nursing students of a university in Turkey. The data were collected using the Personal Information Form, IA Scale, and TM Inventory.


FINDINGS
The IA scale and TM inventory mean scores were 40.83 ± 14.81 and 81.34 ± 11.91, respectively. A significantly negative relationship between students' level of IA and TM skills was found (p <0.05).


PRACTICE IMPLICATIONS
The concept of effective time management should be used in interventions for promoting students' conscious internet use.