![]() ![]() NASA utilizes OPM-approved qualification and rating requirements specific for Aerospace Technology (AST) positions which recognizes NASA's unique aerospace work. Specialized experience is experience that has equipped you with the particular ability, skill, and knowledge to successfully perform the duties of this position and is typically in or related to this line of work. In addition to the Basic Education Requirement (in the Education section below), to qualify for this position you must meet the requirements below. GS-12 ONLY: Start dates will be set after all requirements have been met and verified.If selected, you will be required to complete a financial disclosure statement.You must meet qualifications requirements by the closing date of this announcement.Position subject to pre-employment background investigation.citizens, nationals or those who owe allegiance to the U.S. ![]() Disseminate research results through publication in scientific journals, conference proceedings, presentations, and stakeholder reporting.Work on teams with other researchers to develop, test, assess, and report on novel nondestructive evaluation (NDE) methods to meet NASA's mission needs.Employ mathematical and physics-based theories and models to inform understanding of underlying physics and/or engineering concepts for the development of nondestructive methods.Perform research to yield quantitative damage and/or defect characterization (such as porosity, cracking, delamination defects).Develop, test, and assess quantitative nondestructive evaluation (NDE) methods for advanced materials and structures.Develop and apply signal and data processing algorithms to aid interpretation of nondestructive evaluation (NDE) data.Develop, test, and assess prototype inspection systems that include novel sensors or sensing methods, and data collection for detection of defects.Perform research in nondestructive evaluation (NDE), to include the development of novel electromagnetic based inspection techniques for application to aerospace materials and structures.Duties assigned at a lower grade level will be of more limited scope, performed with less independence and limited complexity duties will be commensurate with the grade of selected employee. Duties described below are at the full-performance level.We start by discussing spontaneous processes and explain why some processes require work to occur even if energy would have been conserved. Snow stating that the first law means “you can’t win.” He paraphrased the second law as “you can’t break even, except on a very cold day.” Unless you are at zero kelvin, you cannot convert 100% of thermal energy into work. In the chapter covering the first law of thermodynamics, we started our discussion with a joke by C. We cannot use internal energy stored in the air to propel a car, or use the energy of the ocean to run a ship, without disturbing something around that object. We cannot unmix cream from coffee without a chemical process that changes the physical characteristics of the system or its environment. Energy cannot arbitrarily pass from one object to another, just as we cannot transfer heat from a cold object to a hot one without doing any work. One such principle is the second law of thermodynamics, which limits the use of energy within a source. So some other thermodynamic principles must be controlling the behavior of physical systems. ![]() For example, when two bodies are in thermal contact, heat never flows from the colder body to the warmer one, even though this is not forbidden by the first law. But this cannot be the only restriction imposed by nature, because many seemingly possible thermodynamic processes that would conserve energy do not occur. (credit: modification of work by NASA/JPL)Īccording to the first law of thermodynamics, the only processes that can occur are those that conserve energy. The ion propulsion engine is the first nonchemical propulsion to be used as the primary means of propelling a spacecraft. Introduction Figure 4.1 A xenon ion engine from the Jet Propulsion Laboratory shows the faint blue glow of charged atoms emitted from the engine.
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