Abstract:
An apparatus and method for estimation of a system having state variables representing the state of the system comprising predicting the estimate of the state variables along with the uncertainties in the state variables; observing a measurement of at least one state variable corrupted with some amount of error; updating the estimates of the state variables using a weighted average, with more weight being given to estimates with higher certainty; and providing an estimator input to update the estimates of the state variables, the estimator input operating to provide asymptotic convergence of the mean estimation error in all of the state variables in the presence of persistent excitation or disturbance that is not asymptotically decaying to zero.
Abstract:
A ring-shaped transistor includes a set of gates. Each gate of the set is disposed between a corresponding source and a corresponding drain. The set of gates are arranged such that all of the set of gates cannot be aligned with fewer than three imaginary straight lines drawn through the gates, with one of the imaginary straight lines passing only once though each of the set of gates.
Abstract:
Porous silicon (PS) films composed of pores with diameters less than 3 nm are fabricated using a galvanic etching approach that does not require an external power supply. A highly reactive, nanoenergetic composite is then created by impregnating the nanoscale pores with the strong oxidizer, sodium perchlorate (NaClO4). The combustion propagation velocity of the energetic composite is measured using microfabricated diagnostic devices in conjunction with high-speed optical imaging up to 930,000 frames per second. Combustion velocities averaging 3,050 m/s are observed for PS films with specific areas of ˜840 m2/g and porosities of about 65-67%. Galvanic etching may also be used to fabricate other porous silicon morphologies and also strong oxidizers other than NaClO4 could be used to create a nanoenergetic porous silicon composite.
Abstract:
A sintered cemented carbide body including tungsten carbide, and a substantially cobalt-free binder including an iron-based alloy sintered with the tungsten carbide. The iron-based alloy is approximately 2-25% of the overall weight percentage of the sintered tungsten carbide and iron-based alloy. The tungsten carbide may be approximately 90 wt % and the iron-based alloy may be approximately 10 wt % of the overall weight percentage of the sintered tungsten carbide and iron-based alloy. The tungsten carbide may comprise a substantially same size before and after undergoing sintering. The iron-based alloy may be sintered with the tungsten carbide using a uniaxial hot pressing process, a spark plasma sintering process, or a pressureless sintering process. The sintered tungsten carbide and iron-based alloy has a hardness value of at least 15 GPa and a fracture toughness value of at least 11 MPa√m.
Abstract:
Provided are materials that include one or more cycloaliphatic polyamides integrated into or coated onto one or more structural fibers such as polyethylene fibers, aramid-fibers, glass fibers or carbon fibers. The resulting materials may be incorporated into composite articles suitable for use as protective equipment or structural layers.
Abstract:
A method and apparatus for receiving signals from an unknown transmitting source and providing the location of the unknown transmitting source comprising a series of channels for receiving signals radiated by the unknown transmitting sources, generating preprocessed time domain data and generating a SAR image depicting a location of the unknown transmitting source, and a processor for processing the preprocessed time domain data to enhance a pixel value at each pixel location within the SAR image by summing signal data from each channel related to each pixel location to generate an enhanced SAR image.
Abstract:
A novel methodology for characterizing and calibrating an entangled photon distribution system is disclosed. The entangled photon distribution system includes at least a source of entangled photon pairs, two photon detectors which detect photons among two channels and a controller. The methodology includes: for at least two different operational setting levels of the source of entangled photon pairs, measuring count rates for photons detected by the two photon detectors, individually and coincidently; fitting the measured individual and coincidence count rate data for the at least two different operational setting levels with theoretical models of detection probability; and determining operational parameters of the system from the fitting. The determined operational parameters of the system include the rate of generated entangled photon pairs by the source, the rates of Raman-scattered photons generated in the first and second channels, respectively, and the efficiency of the two photon detectors, respectively.
Abstract:
A thermoplastic filament comprising multiple polymers of differing flow temperatures in a regular geometric arrangement, and a method for producing such a filament, are described. Because of the difference in flow temperatures, there exists a temperature range at which one polymer is mechanically stable while the other is flowable. This property is extremely useful for creating thermoplastic monofilament feedstock for three-dimensionally printed parts, wherein the mechanically stable polymer enables geometric stability while the flowable polymer can fill gaps and provide strong bonding and homogenization between deposited material lines and layers. These multimaterial filaments can be produced via thermal drawing from a thermoplastic preform, which itself can be three-dimensionally printed. Furthermore, the preform can be printed with precisely controlled and complex geometries, enabling the creation of monofilament and fiber with unique decorative or functional properties.
Abstract:
A thermoplastic filament comprising multiple polymers of differing flow temperatures in a geometric arrangement and an interior channel containing a structural or functional thread therein is described. A method for producing such a filament is also described. Because of the difference in flow temperatures, there exists a temperature range at which one polymer is mechanically stable while the other is flowable. This property is extremely useful for creating thermoplastic monofilament feedstock for three-dimensionally printed parts, wherein the mechanically stable polymer enables geometric stability while the flowable polymer can fill gaps and provide strong bonding and homogenization between deposited material lines and layers. These multimaterial filaments can be produced via thermal drawing from a thermoplastic preform, which itself can be three-dimensionally printed. Furthermore, the preform can be printed with precisely controlled and complex geometries, enabling the creation of a filament or fiber with an interior thread contained within the outer, printed filament or fiber. This thread adds structural reinforcement or functional properties, such as electrical conductivity or optical waveguiding, to the filament.
Abstract:
A photodetector comprising a contact layer; an absorbing region positioned such that light admitted passes into the absorbing region; a diffractive region comprising at least one diffractive element operating to diffract light into the absorbing region; the configuration of the photodetector being determined by computer simulation to determine an optimal diffractive region and absorbing region configuration for optimal quantum efficiency for at least one predetermined wavelength range, the diffractive region operating to diffract light entering through the contact layer such that phases of diffracted waves from locations within the photodetector including waves reflected by sidewalls and waves reflected by the diffractive elements form a constructive interference pattern inside the absorbing region. A method of designing a photodetector comprises using a computer simulation to determine an optimal configuration for at least one wavelength range occurring when waves reflected by the diffractive element form a constructive interference pattern inside the absorbing region.