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Process-Hardened, Multi-Analyte Sensor for Characterizing Multiple Rocket Plume Constituents in a Test Environment

A multi-analyte measurement capability is integrated into a single sensor. Stennis Space Center, Mississippi Stennis Space Center (SSC) is one of three government-operated rocket engine test facilities in the United States and is the primary center for testing and flight-certifying rocket propulsion systems for future space vehicles. Safety is a top priority at NASA-SSC. To safely test and certify rocket engines, monitoring technologies for rocket test stands, which (1) verify compliance with federal, state, and local government guidelines; (2) ensure a safe work environment for its personnel at ground testing facilities; as well as (3) monitor environmental impacts, are all required. Additionally, NASA has a need to monitor engine combustion efficiencies and engine health of a variety of launch vehicle configurations utilizing liquid oxygen, liquid hydrogen, isopropanol, and kerosene. Multi-analyte measurement technology is essential for a safe and effective working environment. Therefore, for the advancement in multi-analyte technology in the rocket testing industry, a device was created that integrates multi-analyte measurements into a single sensor unit.

Posted in: Sensors, Test & Measurement, Monitoring, Articles, Briefs

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Automated Table Lookup Solution Algorithm of the Optimal Powered Descent Guidance for Planetary Landing

NASA’s Jet Propulsion Laboratory, Pasadena, California A novel automated table lookup method is developed to compute the near-fuel-optimal powered descent guidance trajectories, in real-time, for planetary soft landing. The main advantage of this algorithm is that it can be executed autonomously in milliseconds without performing iterative numerical computations to obtain the solution of the optimization problem. The key enabling idea behind this approach is to store, in a lookup table, a number of optimal trajectories that have been computed on the ground for a systematically chosen set of initial conditions. In flight, a near-fuel-optimal trajectory is computed for the actual initial condition by interpolating between these pre-computed trajectories. The lookup method requires only a small, predetermined number of basic algebraic operations. Moreover, this method guarantees that the interpolated solutions are in a prescribed neighborhood of the true optimal solutions.

Posted in: Test & Measurement, Aviation, Articles, Briefs, Aeronautics

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A Continuous-Flow, Microfluidic, Microwave-Assisted Chemical Reactor

The reactor uses a directed 60-GHz source, which may require far less power to observe the same reactivity profiles. NASA’s Jet Propulsion Laboratory, Pasadena, California In industrial synthetic chemistry laboratories, reactions are generally carried out using batch-mode methodologies, stepwise reactions, and purifications to generate a final product. Each step has an associated yield of both the reaction itself and of the final purification that is largely dependent on the procedure being used, and the scientist carrying out the procedure. Continuous-flow reactors are one way of streamlining the process. Furthermore, microwave-enhanced, or microwave-assisted, chemistry has been demonstrated to aid in many of these areas; however, scaling has been a traditional problem with this technique.

Posted in: Physical Sciences, Test & Measurement, RF & Microwave Electronics, Articles, Briefs, TSP, Instrumentation

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Guarded Flat Plate Insulation Test Cryostat

Features include high testing rate and high data quality. John F. Kennedy Space Center, Florida The guarded flat plate insulation test cryostat (Cryostat-500) is a boil-off calorimeter comprising a flat-bottom test apparatus for measuring the absolute thermal performance of an insulation test article. Typical dimensions allow accepting test specimens 200 mm in diameter by up to 30 mm thick. The test chamber is guarded by a second cryogen chamber to prevent parasitic heat loads. System insulation materials provide additional thermal stability for testing over a wide range of environmental conditions. The cold-mass assembly can be configured for rigid or soft materials, with or without compressive loads.

Posted in: Data Acquisition, Test & Measurement, Articles, Briefs, Instrumentation

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Differential Nonlinearity in Analog Measurements

By: Jon Titus, Sealevel Systems, Inc. Q: In a previous answer you noted, "... most applications require linearity but not absolute precision..." What does that mean?

Posted in: Test & Measurement, White Papers, Briefs

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A Portable, Projection Focusing Schlieren System

Heating, ventilation, and air conditioning systems can be monitored using this system, especially those used in commercial kitchens and industrial ventilation. John H. Glenn Research Center, Cleveland, Ohio A new type of projection schlieren camera system (schlierenscope) is more portable, easier to align, and more versatile than existing systems. The schlierenscope is a projection focusing schlieren camera system that can acquire images of shock waves, vortices, gas jets, and other disturbances that create gradients in the refractive index of a transparent medium. These gradients appear as streaks (called schlieren in German) in the resulting image. Thus, a schlierenscope is an apparatus for looking at disturbances in transparent media. The schlierenscope constructed in the project utilizes fast strobes that freeze motion and capture images with a scientific CCD (charge-coupled device) camera. The schlierenscope is unique among schlieren instruments because all of the critical controls are contained within the instrument housing.

Posted in: Test & Measurement, Briefs, TSP

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Cryogenic and Non-Cryogenic Optical Liquid Level Instrument for Stratified Conditions

Marshall Space Flight Center, Alabama Typical cryogenic tank metering systems use a series of thermocouple, RTD, or other temperature or resistive devices in a rake or array configurations. Since these operate using the thermal change between the liquid and gas fluid phases, they are limited by thermal latency (the time it takes the sensing element to respond to the temperature). In addition, cryogenic fluids often create a volatile boundary or sloshing layer. This layer causes uncertainties of the true fluid boundary in a tank. Finally, accuracy and resolution are determined by the number of sensing segments used. These are typically tied to individual data channels, which puts a strain on data acquisition systems to achieve continuous and high-accuracy values.

Posted in: Test & Measurement, Briefs

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