30 results about "Relative attenuation" patented technology

The invention provides a system (2) for non-invasive detection of the state of hydration in a living specimen, the system including an RF generator/transmitter (416) for emitting RF radiation signals and for transmitting the radiation signals through a tissue of a living specimen; an RF receiver (8) for receiving RF signals transmitted through the tissue, and for feeding the signals to a processor (10) for comparison of relative attenuation of RF frequencies passing through the tissue with a reference attenuation ratio signal, and an indicator unit (12) for providing an output signal representative of the water content level of the tissue. A method for non-invasive detection of the state of hydration in a living specimen is also described and claimed.

A large-mode-area (LMA) optical fiber (10) that operates as a single-mode optical fiber. The optical fiber includes a core region (20) surrounded by an inner cladding (32), which in turn is surrounded by an outer cladding (40). The inner cladding includes at least one up-doped ring region (32R1). The ring region is configured to form a large attenuation differential between the higher-order modes and the fundamental mode so only that the fundamental mode remains traveling in the optical fiber. If necessary, the optical fiber can include a bend (10B) having a select “resonant” bend diameter (DB) that increases the relative attenuation of the fundamental and higher-order modes. The optical fiber supports an effective mode field diameter (MFD) of up to 40 μm to 50 μm. As a result, detrimental non-linear effects are suppressed, which allows the optical fiber to carry substantially more optical power than conventional LMA optical fibers. The LMA optical fiber is thus eminently suited for a number of optical-fiber-based applications calling for high optical power, such as fiber lasers and pump sources for wavelength conversion.

An apparatus and method of processing X-ray projection data including spectral computed tomography (CT) projection data. The spectral CT data is decomposed into material projection lengths using a material-decomposition method that includes an initial-estimate method to provide an initial projection-lengths estimate. The initial-estimate method can include first reconstructing an image using non-spectral CT data, and then subdividing the reconstructed image into materials according to the relative attenuation density of areas within the reconstructed image (e.g., high attenuation areas correspond to a high attenuation material such as bone). The projection length estimates of each material are then obtained by forward projecting the corresponding subdivision of the reconstructed image. Also, the initial estimate can be obtained/refined by selecting the projection lengths with smallest cost-function value from randomly chosen projection lengths within a sample space. The initial estimate can also be conditioned on the X-ray flux at the X-ray source.

The invention relates to a device used for monitoring hydrocephalus and encephaledema. The device comprises a signal encoding generator, an emission electrode, a receiving electrode, a signal processing digital converter, an orthogonal regulator, a detector, a parameter assessment device, a resistance analyzer and an assessment instrument. The invention also relates to a method used for monitoring hydrocephalus and encephaledema, which comprises the following steps of: intruding into the lower part of the skull skin; emitting electromagnetic waves; carrying out amplification and filter processing on the received electromagnetic waves, and converting the electromagnetic waves into digital signals; carrying out orthogonalization processing on the digital signals; detecting synthetic signals and orthogonal signals of the electromagnetic waves; calculating the relative attenuation coefficients, the relative phase displacement, the transmission speed difference and the complex wave value K; calculating the complex impedance Z and capacitance; and assessing hydrocephalus and encephaledema. According to the invention, hydrocephalus and encephaledema situations can be monitored and assessed all day in a non-intrusive mode so as to reduce the treatment risks.

Acoustic heterodyne radars use accurately surveyed or otherwise known locations to repetitively launch at least two, intense acoustic tone soundwaves (F1, F2) into an underground area of search. An acoustic receiver is tuned to receive either the sum (F1+F2) or difference (|F1−F2|) heterodynes and is configured to measure and log the overall relative attenuation and roundtrip travel times of the soundwaves, like a typical radar. Any acoustic heterodynes received are assumed to be the work of non-linearities and stresses in the search area. A full-waveform three dimensional tomography algorithm is applied by a graphics processor to the collected and logged data to generate maps and profiles of objects beneath the ground which are interpreted to have produced the acoustic heterodynes.

The invention discloses a method for measuring attenuation coefficient of fast and slow shear waves under crack width of rock core. According to the method, by measuring amplitude of fast and slow shear waves before and after fracturing and introducing relative attenuation coefficient, corresponding relative attenuation coefficient of fast and slow shear waves before and after fracturing is calculated, and corresponding relative attenuation coefficient without cracks is subtracted from the relative attenuation coefficient after cracks so as to obtain the influence of cracks on attenuation of fast and slow shear waves. By the method, the influence of anisotropy of a rock sample on attenuation of fast and slow shear waves can be eliminated, and only by considering the influence of crack width on attenuation of fast and slow shear waves, quantitative evaluation of cracks can be realized.

Circuits and methods for eliminating or mitigating the amount of temperature-dependent variation in the relative attenuation of a multi-valued digital step attenuator (DSA) by using resistive components having temperature-dependent resistance values that compensate for or offset changes in the temperature-dependent ON resistance (R_ON) of the switches within the DSA. In some embodiments, DSA attenuator cell switches are fabricated to have positive first-order resistance temperature (FORT) coefficients, while temperature-compensating series attenuation resistances are fabricated as a positive FORT coefficient resistor and temperature-compensating shunt resistances are fabricated as either a negative FORT coefficient resistor or a combination of a negative FORT coefficient resistor in parallel with a positive FORT coefficient resistor.

The invention discloses an attenuator based on capacitance compensation, the attenuator comprises a transistor switch, a parallel attenuation resistor, a parallel open-circuit line capacitor and a matching transmission line, and the attenuator utilizes the switch to switch an attenuation state and a direct connection state so as to realize the control of relative attenuation; the attenuator is simple in structure, small in occupied area and good in parasitic phase modulation and attenuation characteristic bandwidth, and has great advantages and application space in monolithic integrated circuit application.

The invention belongs to the technical field of tissue optical measurement and relates to a calibration method for a time domain fluorescence chromatography imaging system. The method is used for calibrating transmission factors of each passage of a system and comprises the following steps that: a calibration device used for replacing an imaging cavity in an imaging system is built; a source optical fiber and a detection optical fiber are respectively inserted onto the imaging cavity; some pieces of lens paper are placed into an insertion groove, and the detection optical fiber is connected with the first passage; a 780nm laser is opened, and the attenuation rate of all neutral filters arranged on a filter wheel corresponding to the passage is calibrated; the 780nm laser is turned off, an830nm laser is turned on, and the transmission rate of 830nm long pass filters arranged on a filter wheel corresponding to the passage is calibrated; and the steps are repeated, and the calibration of the relative attenuation rate of all neutral filters arranged on the filter wheel on each passage and the transmission rate of the 830nm long pass filters is completed. The differences on the systempassage transmission performance can be eliminated.

The invention discloses a wireless network coverage blind area detection method, which comprises the following steps: determining a user position and a user moving speed according to signaling data fed back by a user terminal; removing user data of fast moving users; calculating a relative attenuation value of a medium-low speed user signal; determining the depth fading point according to the relative attenuation value of the user signal, and determining the suspected coverage blind area according to the distribution of the depth fading point. if the suspected coverage blind area is kept in the deep fading state, determining the suspected coverage blind area as the signal coverage blind area. Compared with the existing method, the method of the invention fully utilizes the existing data ofthe operator, can calculate and obtain more accurate user moving speed so as to effectively eliminate invalid user data, and utilizes the relative attenuation value of the user signal, thereby improving the detection precision of covering the blind area and saving manpower and material resources.

The invention relates to a method for directional signal processing for a hearing aid, which includes generating first and second input signals from an ambient sound signal using first and second input transducers of the hearing aid; forming first and second directional signals based on the first and second input signals, the second directional signal having relative attenuation in directions of a first useful signal source, the first directional signal having relative attenuation in directions of a second useful signal source; ascertaining first and second amplification parameters; defining a reference directional characteristic; as a function of the reference directional characteristic, ascertaining corrected first and second amplification parameters so that an output directional signal, formed as a sum of the first directional signal weighted by using the first corrected first amplification parameter and the second directional signal weighted by using the corrected second amplification parameter, merges into a linearly scaled reference directional signal upon the first amplification parameter being equal to the second amplification parameter.

The invention relates to a directional signal processing method for a hearing device. The method comprises the steps of generating a first input signal by means of a first input converter according toa sound signal in the environment, generating a second input signal by means of a second input converter according to the sound signal, generating a forward signal and a backward signal according tothe first input signal and the second input signal, respectively, determining a first orientation parameter as a linear factor of a linear combination of the forward signal and the backward signal, such that a first directional signal formed by the linear combination has a maximum attenuation in the first direction; determining the correction parameter such that the second directional signal has adefined relative attenuation in the first direction, generating a second directional signal from the forward signal and the backward signal according to the first directional parameter and the correction parameter, or from the first directional signal and the omnidirectional signal according to the correction parameter, and generating an output signal of the hearing device according to the seconddirectional signal.