摘要:
A active noise control system is described for attenuating an undesirable noise that containing multiple noise components having different frequencies. The system includes a configuration of signal generators and corresponding paired adaptive filters. Each signal generator produces a generator output signal containing one or more sinusoidal signal components, with each signal component having a frequency corresponding to a respective one of the noise frequency components. Separate signal generators are used to produce those sinusoidal components having frequencies corresponding to noise component that are adjacent with respect to their frequencies. Each adaptive filter operates on the generator output signal produced by its corresponding paired signal generator in accordance with its filtering characteristics to provide a respective filtered output signal. The filtered output signals from each adaptive filter are summed to obtain an output canceling signal, which drives an actuator to produce output canceling waves that are superpositioned with the undesirable noise. An error sensor measures the level of residual noise resulting from the superposition of the canceling waves and the undesirable noise, and provides an error signal for adapting the characteristics of the adaptive filters so as to minimize the level of residual noise.
摘要:
Embodiments of the present disclosure disclose a wireless base station and a method for receiving a signal of the wireless base station. The wireless base station includes a base station indoor apparatus and a base station outdoor apparatus. The base station outdoor apparatus includes an adapter, a terrestrial service antenna, and a satellite antenna. The terrestrial service antenna is a microwave transmission antenna or a wireless access antenna. The base station indoor apparatus includes a satellite signal processing module configured to obtain a satellite service signal by decoding on a satellite radio-frequency signal received by the satellite antenna. The satellite antenna and the terrestrial service antenna are connected to the adapter. The adapter is configured to couple a signal received by the satellite antenna and a signal received by the terrestrial service antenna, and transfers a coupled signal to the base station indoor apparatus through a first data line.
摘要:
The invention provides compounds that are A-type procyanidins. The compounds can be prepared by reacting flavylium salts with catechins or analogs thereof, for example, under anhydrous conditions in alcohol.
摘要:
A method for preparing A-type procyanidins is provided by reacting flavylium salts with catechins and analogs thereof, under anhydrous conditions in alcohol.
摘要:
The invention provides compounds that are A-type procyanidins. The compounds can be prepared by reacting flavylium salts with catechins or analogs thereof, for example, under anhydrous conditions in alcohol.
摘要:
An active noise control (ANC) system is disclosed for attenuating engine generated noise that contains at least one sinusoidal noise component having an amplitude and frequency that vary with changes in engine rotational speed. The ANC system includes a means for generating at least one generator output signal that contains one or more sinusoidal signal components, where the frequency of each signal component corresponds to the frequency of a respective noise component. A separate control signal having an amplitude that varies with engine rotational speed is generated to correspond with each generator output signal. Each generator output signal is then multiplied by its respective control signal to produce a corresponding filter input signal. Each filter input signal passes to a respective adaptive filter, where it is filtered to produce a corresponding filter output signal according to the adjustable filtering characteristics of the adaptive filter. Noise canceling waves are generated by a noise canceling actuator in response to each filter output signal, and the canceling waves are superimposed with the undesirable noise generated by the engine. The level of residual noise resulting from this superposition is sensed, and an error signal is developed to represent the residual noise level. The filtering characteristics of each adaptive filter are adaptively adjusted based upon the error signal to minimize the residual noise level. In the preferred embodiment, each control signal has its amplitude determined in accordance with a respective predetermined function based upon the sensed engine rotational speed, and each predetermined function is correlative of the amplitude behavior of those noise components corresponding to the signal components contained in the generator output signal that is multiplied by the respective control signal.
摘要:
The invention provides compounds that are A-type procyanidins. The compounds can be prepared by reacting flavylium salts with catechins or analogs thereof, for example, under anhydrous conditions in alcohol.
摘要:
The invention provides compounds that are A-type procyanidins. The compounds can be prepared by reacting flavylium salts with catechins or analogs thereof, for example, under anhydrous conditions in alcohol.
摘要:
A method, system and computer program product are provided for implementing automatic access control list validation using automatic categorization of unstructured text. Automatic categorization of unstructured text is performed on a plurality of documents of an access control list for determining an average term vector. Each of the documents is scored against the average term vector to identify a dissimilar document, flagged as a possible security risk. Automatic categorization of unstructured text is performed on user information of a plurality of members of a candidate access control list for determining a typical term vector. A similarity score is determined by user information and the typical term vector, members of an access control list that are dissimilar from other members of the access control list are identified.
摘要:
A method for preparing A-type procyanidins is provided by reacting flavylium salts with catechins and analogs thereof, under anhydrous conditions in alcohol.