MEMs

Embedded Development and the .NET Micro Framework

The scenario:

You’ve been assigned the task of designing and producing an embedded device. You’ve been given time, cost and size constraints that impact your design. An initial analysis of the requirements leads you to the conclusion that a 32-bit processor with a relatively small amount of RAM and Flash are required. A bit of research shows that an ARM processor with 2MB of external Flash and 2MB of external RAM will meet your cost and size constraints.

Posted in: Articles, Articles, Electronics & Computers, Architecture, Embedded software, Product development
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Multiscale Virtual Design and Testing of Materials

Progress has been made in research on several fronts in an effort to develop computational simulation capabilities for use in virtual design and testing of advanced structural materials. It is envisioned that the capabilities will be embodied in a coherent set of methods, software to implement the methods, and advances in the fundamental understanding of many issues in the thermomechanical performance of materials. It is further envisioned that the methods and software will be organized into a hierarchy (see figure) corresponding to a hierarchy of spatial scales from electronic through atomic, mesoscale, microstructural, and continuum to macrostructural, and that there will be seamless coupling of information from each scale to the next larger scale. A secondary objective of this research and development effort is to provide direct simulation output at each level of the hierarchy for investigating specific phenomena at the corresponding spatial scale. For the purposes of demonstrating the capabilities and providing specific focus for the overall research, it is intended to predict nano-, micro-, and macroscopic degradation of aluminum and titanium alloys under fatigue loading and in a corrosive (oxidative) environment and as a function of temperature.

Posted in: Briefs, Information Technology, Design processes, Simulation and modeling
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Life Tests of a Microwave MEMS Capacitive Switch

Life tests have demonstrated the longevity of an electrostatically actuated capacitive switch of a microelectromechanical systems (MEMS) type suitable for handling radio signals having frequencies of multiple gigahertz. The tests were performed to contribute to understanding of factors that affect the reliability of MEMS switches in general and of how improvements in designs and materials can increase operational lifetimes of MEMS capacitive switches. The tests were based partly on the concept that data obtained in monitoring both high-speed and low-speed switching characteristics provide valuable insight into quantifying the lifetime properties of the switches and enable estimation of switching lifetimes under a variety of operating conditions.

Posted in: Briefs, Electronics & Computers, Microelectricmechanical device, Switches
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Measuring Corrosion-Related Properties of Coupled Metals

Amethod and apparatus have been conceived for using electrochemical impedance spectroscopy (EIS) for determining rates of corrosion of coupled metals. EIS has been used heretofore for determining rates of corrosion of single metals. However, many structures used in corrosive environments include different metals in electrical contact. Moreover, the concept of using a sacrificial metal to suppress or reduce the corrosion of another metal is applied in some structures. The coupling of two different metals can affect the rates of corrosion of both. Hence, there is a need to extend EIS to coupled metals.

Posted in: Briefs, Physical Sciences, Spectroscopy, Corrosion, Metals
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Scaling of Flight Tests of Unmanned Air Vehicles

A program of research has addressed a methodology of scaling of flight tests of unmanned air vehicles (UAVs) intended primarily for military use in observing and/or attacking targets on the ground. The main goal of this research is to make it possible to design a model UAV that is suitable for evaluating the performance of a given real UAV or family of UAVs. This research also demonstrates the use of results of computational simulations and ground hardware experiments on models of vehicles other than UAVs to predict performances of UAVs prior to conducting flight tests.

Posted in: Briefs, Physical Sciences, Flight tests, Unmanned aerial vehicles
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Small-Scale Combustion-Chamber Testing Facility

A small-scale combustion-chamber testing facility has been designed and partly built for use in evaluating advanced combustor designs for future gas turbine engines. The specific model combustor for which the facility was designed is an approximation of a planar section of an ultra-compact combustor (UCC). In the full-scale UCC (Figure 1), vanes in an annular cavity are positioned and oriented to cause the combustion gases to flow in a spiral pattern and the resulting centripetal acceleration in the cavity is utilized to increase the speed of combustion and thereby make it possible to design the combustion chamber to be shorter than would otherwise be necessary. In the model combustor, the spiral aspect of the flow is approximated by means of a small flow of air directed perpendicular to a main flow. The design of the facility and the model combustor provides access for off-axis optical (including visual) observation and measurement of cavity-vane interactions. The facility can also be used to test many other combustor models.

Posted in: Briefs, Manufacturing & Prototyping, Combustion chambers, Test facilities
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Interactive DataWall

The Interactive DataWall (IDW) is a computer-driven, high-definition display, large enough to be visible simultaneously to multiple observers, that presents information from multiple sources and exploits advanced techniques of human/computer interaction and data fusion. The IDW originally was intended for collaborative use by a group of Air Force decision-makers who must consider large amounts of dynamic information (e.g., information pertinent to targeting during battle). Sources of displayed and otherwise utilized information can include sensors on terrestrial vehicles, sensors aboard satellites, databases, and video feeds from remote locations.

Posted in: Briefs, Electronics & Computers, Data acquisition and handling, Human factors, Displays, Collaboration and partnering
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Miniature Semiconductor Diodes as Pumps and Motors

Experiments have shown that when a miniature semiconductor diode floats in an aqueous solution and an alternating electric field is applied, (1) the diode rectifies the alternating potential induced between the electrodes, and (2) the resulting pulsating DC potential gives rise to an electro-osmotic flow in the vicinity of the diode and associated force that orients the diode along the electric-field direction, and propels the diode through the water. The propulsive force on the diode is along the electricfield direction and can be toward the cathode or the anode end, depending on the precise nature of the surface charge on the diode and the chemical composition of the solution. It has been proposed to exploit this phenomenon in developing microscale and nanoscale pumps and motors for diverse purposes. The proposal is not as radical as it might first seem: Electro-osmosis in applied DC electric fields has been used to pump liquids in microfluidic devices.

Posted in: Briefs, Electronics & Computers, Semiconductor devices, Pumps
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Optical-Fiber Infrasound Sensors

Optical-fiber infrasound sensors (OFISs) are being developed for detecting acoustic pressures in the frequency range from a few millihertz to a few hertz. As explained below, these sensors were conceived to overcome some of the limitations of prior infrasound sensors based on pipe filters connected to microbarographs.

Posted in: Briefs, Photonics, Fiber optics, Sensors and actuators, Acoustics
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Study of Membrane Optics for Lightweight Space Telescopes

Astudy has been performed to establish a foundation for the analysis, design, and further development of inplane- actuated deformable membrane mirrors for lightweight spaceborne telescopes. It is envisioned that the telescopes, having typical mirror diameters of 20 m or larger, would be stowed compactly for launch and transport, then deployed in orbit around the Earth for use in surveillance of the Earth and in exploration of deep space.

Posted in: Briefs, Photonics, Mirrors, Optics, Test equipment and instrumentation
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