Abstract: This patent provides for a method and apparatus for mitigating the formation of concentrated wake vortex structures generated from lifting or thrust-generating bodies and maneuvering control surfaces wherein the use of contour surface geometries promotes vortex-mixing of high and low flow fluids. The method and apparatus can be combined with various drag reduction techniques, such as the use of riblets of various types and/or compliant surfaces (passive and active). Such combinations form unique structures for various fluid dynamic control applications to suppress transiently growing forms of boundary layer disturbances in a manner that significantly improves performance and has improved control dynamics.

Abstract: A self-adjusting hold-off trigger circuit and method detects a threshold crossing between consecutive samples of a digitized input signal as edge events, identifies the crossing as a qualified trigger event if the crossing is in a desired direction based upon trigger criteria, and provides a trigger output when the qualified trigger event occurs greater than an approximate average or peak time after a preceding edge event.

Abstract: A mixed signal measurement instrument provides for the display of both analog and logic signal waveforms using a “no dead time” architecture. For a logic signal all trigger events are detected, the logic signal is sampled at a high rate to produce a sampled logic signal data, the sampled logic signal data are delayed to provide a pre-trigger delay and then are drawn in real time in response to the detected trigger events. A FIFO is used to delay the sampled logic signal data, with the position of the trigger event on the display being determined coarsely by an effective depth of the FIFO. The sampled logic signal data may also be compressed into compression codes prior to the FIFO. A fast drawing engine receives the sampled logic signal data from the FIFO as either data samples or compression codes, and draws a logic waveform using four rows of the drawing engine memory—one row for each of four logic states.

Abstract: A fast rasterizer uses a fast memory that has a bit-set port for receiving data and a totally independent readout and clear port for outputting a waveform image. The fast memory is organized into rows and columns corresponding to the rows and columns of a raster display device, with each memory location or cell holding a single bit. The fast memory is divided into parallel sections so that one column of each section may be written into each clock cycle, resulting in the possibility of writing a plurality of columns into the fast memory each clock cycle. Each memory cell is set when a row and column write signal for the cell are asserted, and is read out and cleared when a row and column read signal for the cell are asserted. Row logic using thermometer codes is used to set the row lines for the selected column in each section.

Abstract: A “no dead time” data acquisition system for a measurement instrument receives a digitized signal representing an electrical signal being monitored and generates from the digitized signal a trigger signal using a fast digital trigger circuit, the trigger signal including all trigger events within the digitized signal. The digitized signal is compressed as desired and delayed by a first-in, first-out (FIFO) buffer for a period of time to assure a predetermined amount of data prior to a first trigger event in the trigger signal. The delayed digitized signal is delivered to a fast rasterizer or drawing engine upon the occurrence of the first trigger event to generate a waveform image. The waveform image is then provided to a display buffer for combination with prior waveforms and/or other graphic inputs from other drawing engines. The contents of the display buffer are provided to a display at a display update rate to show a composite of all waveform images representing the electrical signal.

Abstract: A data management method for a long record length memory that is used for data acquisition writes data samples into an initial circular buffer within the memory having a size equal to a pre-trigger time. When a first trigger event occurs, the data samples are then written into a linear region after the circular buffer within the memory. The data sample acquisition in the linear region continues until a post-trigger and new pre-trigger time have elapsed after a last trigger event, at which point the acquisition terminates and the new pre-trigger time becomes a new circular buffer for a next trigger event. In this way all trigger events are captured with associated pre-trigger and post-trigger data.

Abstract: An improved digital trigger circuit has a plurality of data samples extracted from an input electrical signal for each sample clock cycle. The plurality of data samples are compared in parallel with a high threshold level and a low threshold level which provides hysteresis for noise rejection. Also the plurality of data samples are used to determine sub-sample trigger positioning. The comparison outputs are input to a digital trigger logic circuit for identifying a selected trigger event and generating a trigger for the acquisition of data from the input electrical signal for analysis and display. The digital trigger logic provides edge event triggering, pulse width triggering and transition time triggering, among others.

Abstract: A waveform compression and display technique saves both a peak detected version (background version) and a decimated/lowpass filtered version (foreground version) of a sampled electrical signal. The two versions are displayed simultaneously overlaid together in a contrasting manner so as not to obscure information contained in either of them. The lowpass filtered version uses a series of simple lowpass filters with decimation to produce a single data stream from a plurality of data streams derived from the sampled electrical signal. The single data stream may then be subjected to additional filtering, such as a cascaded integrator-comb filter, to obtain a desired frequency bandwidth. When displayed, the peak detect pixels adjacent the decimated/lowpass filtered pixels may be adjusted in intensity so that the low frequency information of the lowpass filtered waveform is not lost, while the peak detect pixels further from the lowpass filtered pixels are intensified to highlight the high frequency information.

Abstract: A tube manufacturing system is provided that is capable of manufacturing tube structures that are on the nanoscale and larger. The system provides for control as to the structure and atomic makeup of the feed sheet material used and provides motive force to the sheet material being used to continuously advance the sheet material through the various system components. After the tube structures are formed, they may be used in providing a source material for manufacturing macroscopic objects thus increasing the level of performance and capabilities of such objects due to the engineered properties of the tube structures formed within this system and method of manufacturing. Processes for manufacturing of nanotubes are also disclosed, as are nanotubes manufactured by the processes and system of the invention.

Abstract: Aircraft landing gear comprised of a wheel hub motor/generator disks stack, includes alternating rotor and stator disks mounted with respect to the wheel support and wheel. The wheel hub motor/generator can provide motive force to the wheel when electrical power is applied, which may be applied prior to touch-down thus decreasing the difference in relative velocities of the tire radial velocity with that of the relative velocity of the runway thus greatly reducing the sliding friction wear of said tire. After touchdown the wheel hub motor/generator may be used as a generator thus applying a regenerative braking force and/or a motorized braking action to the wheel. The energy generated upon landing maybe dissipated through a resistor and/or stored for later use in providing a source for motive power to the aircraft wheels for the purpose of taxiing and ground maneuvers of said aircraft.

Abstract: Aircraft landing gear comprised of a wheel hub motor/generator disks stack, includes alternating rotor and stator disks mounted with respect to the wheel support and wheel. The invention can provide motive force to the wheel when electrical power is applied, e.g. prior to touch-down, thus decreasing the difference in relative velocities of the tire radial velocity with that of the relative velocity of the runway and reducing the sliding friction wear of the tire. After touchdown the wheel hub motor/generator may be used as a generator thus applying a regenerative braking force and/or a motorized braking action to the wheel. The energy generated upon landing maybe dissipated through a resistor and/or stored for later use in providing a source for motive power to the aircraft wheels for taxiing and ground maneuvers of the aircraft. Methods and apparatuses for nose gear steering and ABS braking using the disclosed invention are described.

Abstract: A test and measurement Instrument samples an input digital logic signal to produce logic samples, compresses the logic samples into compression codes, and stores the compression codes into acquisition memory. Compression includes parsing the logic samples into groups and assigning compression codes to those groups, and is performed so as not to lose information about the input digital logic signal's activity. The instrument converts the stored compression codes into a waveform image in display memory and displays the stored waveform image on a display device.

Abstract: Aircraft landing gear comprised of a wheel hub motor/generator disks stack, includes alternating rotor and stator disks mounted with respect to the wheel support and wheel. The invention can provide motive force to the wheel when electrical power is applied, e.g. prior to touch-down, thus decreasing the difference in relative velocities of the tire radial velocity with that of the relative velocity of the runway and reducing the sliding friction wear of the tire. After touchdown the wheel hub motor/generator may be used as a generator thus applying a regenerative braking force and/or a motorized braking action to the wheel. The energy generated upon landing maybe dissipated through a resistor and/or stored for later use in providing a source for motive power to the aircraft wheels for taxiing and ground maneuvers of the aircraft. Methods and apparatuses for nose gear steering and ABS braking using the disclosed invention are described.

Abstract: A method of verifying the integrity of an arithmetic logic unit (ALU) of a control module includes inputting a first test value into one of a plurality of registers of the ALU and inputting a second test value into remaining registers of the plurality of registers. A first set of operations is performed between the one of the plurality of registers and each of the remaining registers to produce a first set of results. A fault is indicated when one of the first set of results varies from a first predetermined result.

Abstract: A tube manufacturing system is provided that is capable of manufacturing tube structures that are on the nanoscale and larger. The system provides for control as to the structure and atomic makeup of the feed sheet material used and provides motive force to the sheet material being used to continuously advance the sheet material through the various system components. After the tube structures are formed, they may be used in providing a source material for manufacturing macroscopic objects thus increasing the level of performance and capabilities of such objects due to the engineered properties of the tube structures formed within this system and method of manufacturing. Processes for manufacturing of nanotubes are also disclosed, as are nanotubes manufactured by the processes and system of the invention.

Abstract: Aircraft landing gear comprised of a wheel hub motor/generator disks stack, includes alternating rotor and stator disks mounted with respect to the wheel support and wheel. The wheel hub motor/generator can provide motive force to the wheel when electrical power is applied, which may be applied prior to touch-down thus decreasing the difference in relative velocities of the tire radial velocity with that of the relative velocity of the runway thus greatly reducing the sliding friction wear of said tire. After touchdown the wheel hub motor/generator may be used as a generator thus applying a regenerative braking force and/or a motorized braking action to the wheel. The energy generated upon landing maybe dissipated through a resistor and/or stored for later use in providing a source for motive power to the aircraft wheels for the purpose of taxiing and ground maneuvers of said aircraft.

Abstract: A method and apparatus for an improved timer circuit and improved pulse width detection includes initiating a ramp timer and setting a timer latch output level substantially simultaneously in response to the occurrence of an input signal. The occurrence of the input signal also causes a counter to be enabled to count clock cycles. The ramp timer signal of the ramp timer is frozen (i.e., paused) by a timer control circuit, upon the occurrence of a first clock cycle following the enabling of the counter. The counter then counts a predetermined number of clock cycles after the ramp timer signal is frozen and, upon the occurrence of a last one of a predetermined number of clock cycles, generates a terminal count signal. Upon receiving the terminal count signal, the timer control circuit unfreezes ramp timer signal. The ramp timer runs until completion at which time the ramp timer generates an end of ramp control signal. The control signal is communicated to timer latch to reset timer latch output level.

Abstract: For alias detection in the frequency domain a method is provided of acquiring a signal under test (SUT) at each of a first sample rate and a second sample rate to provide thereby respective first and second streams of samples, processing the first and second streams of samples according to a first function to determine thereby respective spectral energy distributions, and comparing the spectral energy distributions to determine thereby a spectral region including spectral energy common to each of the spectral energy distributions.

Abstract: A DDS pulse generator has an accumulator that accumulates a phase increment value to produce phase accumulator values, and has a lookup table that contains a digital representation of a pulse waveform such that a pulse output signal is produced from the lookup table in response to the phase accumulator values. To change a period of the pulse output signal without changing edge positions a programmable modulo value is used. An address mapper is situated between the accumulator and address lines of the lookup table to map the rising and falling edge portions of the phase accumulator values into large regions of the lookup table, while phase accumulator values corresponding to high and low logic levels are mapped into small regions of the lookup table. The resulting pulse output signal has easily independently controlled period and pulse width as well as rising and falling edge speeds.

Abstract: A triggered DDS generator architecture accumulates a phase increment value in response to a DDS clock to generate phase accumulator values for addressing a waveform lookup table which contains a desired output signal. A time measurement circuit determines a time interval between the arrival of a trigger signal and a subsequent cycle of the DDS clock, which time interval is used to either adjust an initial phase accumulator value or delay the DDS clock so that a constant time is maintained between the arrival of the trigger signal and the desired output signal.