Special Coverage


A Large-Eddy Simulation Model of the Atmospheric Boundary Layer

The model includes the interaction of various physical processes, including turbulence, clouds, precipitation, and radiation. NASA’s Jet Propulsion Laboratory, Pasadena, California The atmospheric boundary layer is the lowermost layer of the atmosphere and is host to a plethora of physical processes that significantly affect weather, climate, and air quality. In many applications, detailed information about the boundary layer is required at high temporal and spatial resolution. The main purpose of the current model is to provide accurate and finely resolved inspace and time predictions of the atmospheric boundary layer. High-resolution predictions of the boundary layer are typically pertinent in the development and evaluation of weather and climate models, in fundamental studies of atmospheric dynamics including clouds and precipitation, the dispersion of pollutants, and the development of remote sensing instruments.

Posted in: Briefs, Electronics & Computers, Simulation Software


Hydrogen Peroxide for Microbial Growth Control in Space Potable Water Systems

This on-demand generator can provide the needed hydrogen peroxide levels for microbial growth control in potable water holding tanks and waterlines. Marshall Space Flight Center, Alabama NASA uses a biocide to prevent contamination of astronaut drinking water with harmful microorganisms. Concerns have arisen over existing biocides — that they’re inadequately effective, and may have toxic side effects when consumed. New microbial control methods are a priority. This need is addressed by using an electrochemical reactor for on-demand generation of hydrogen peroxide (H2O2) solutions. The device uses onboard resources only. The method eliminates the need for resupply items (reducing launch costs), and reduces toxicity risk.

Posted in: Briefs


Nonlinear Swept Frequency Technique for CO2 Measurements Using a CW Laser System

The measurements would be used to significantly reduce the uncertainties in global estimates of CO2, improve climate models, and close the carbon budget for improved forecasting and policy decisions. Langley Research Center, Hampton, Virginia The U.S. National Research Council recently identified the need for a near-term space mission of Active Sensing of CO2 Emissions over Nights, Days, and Seasons (ASCENDS). The primary objective of the ASCENDS mission is to make CO2 column measurements across the troposphere during the day and night over all latitudes and all seasons, and in the presence of scattered clouds. These measurements would be used to significantly reduce the uncertainties in global estimates of CO2 sources and sinks, provide an increased understanding of the connection between climate and CO2 exchange, improve climate models, and close the carbon budget for improved forecasting and policy decisions.

Posted in: Briefs, TSP, Greenhouse Gases, Lasers & Laser Systems


Method of Water Regeneration From Waste and Cascade Distillation

Lyndon B. Johnson Space Center, Houston, Texas Effective recovery of potable water from various streams and sources of wastewater, seawater, or contaminated water is a significant task for securing existence of human beings in space, terrestrial, and marine environments. Efficient purification of the wastewater is also a very important task for protection of the global environment. The existing and known methods of recovery of clean water from the wastewater are technically complicated, have low energy efficiency, consume processing material, and are bulky, heavy, and not cost effective.

Posted in: Briefs, Recycling Technologies


PLC-Based Robotic Controls Versus OEM Robotic Controls

As more manufacturing facilities and distribution centers discover the benefits of robotic material handling solutions, the decision of how best to control the robot must be made. While robot original equipment manufacturers (OEMs) offer their own tightly integrated controller, recent developments have enabled control by a Programmable Logic Controller, or PLC. For facilities where PLC-based controls are already used in other machine control applications, the benefits of using one for the robot as well may be a wiser choice than the OEM controller. Let’s review PLC-based robotic control to help you determine if it’s the best choice for your application.

Posted in: Articles, Industrial Controls & Automation, Robotics


Reducing Power-On/Off Glitches in Precision DACs

Voltage glitches are common in a signal chain path, especially when the system is being powered up or down. Depending on the peak amplitude and glitch duration, the end result in the system output can be catastrophic. One example is an industrial motor control system where a digital-to-analog converter (DAC) drives the motor drivers to control motor spin. If the glitch amplitude is higher than the motor driver’s sensitivity threshold, the motor could be spinning without control in any direction when the system is powered up/down.

Posted in: Briefs, Power Management, Motors & Drives


Piezoelectric Actuated Inchworm Motor (PAIM)

This linear piezoelectric actuator can operate at temperatures of 77 K or below. NASA’s Jet Propulsion Laboratory, Pasadena, California Conventional piezoelectric materials, such as PZTs, have reasonably high electromechanical coupling over 70%, and excellent performance at room temperature. However, their coupling factor (converting electrical to mechanical energy and vice versa) drops substantially at cryogenic temperatures, as the extrinsic contributions (domain wall motions) are almost frozen out below 130 K.

Posted in: Briefs, TSP, Fluid Handling, Motors & Drives