171 results about "Excitation amplitude" patented technology

The invention discloses a micro-movement friction and abrasion testing machine. The micro-movement friction and abrasion testing machine is that two symmetrically arranged electric vibration exciters are adopted and used as excitation sources for generating micro-movement friction between friction pairs; a loading device is adopted and used for applying positive pressure to the friction pairs; a force sensor is adopted and used for collecting a positive pressure signal; a computer data processing device is arranged and produces a closed-loop feedback control together with the acquired positive pressure signal, and the load applied by the loading device is kept constant. In addition, the computer data processing device is used for recording and analyzing the positive pressure signal acquired by the sensor, a micro-movement friction force signal, and a displacement signal, acquired by a displacement sensor, of each electric vibration exciter and then are automatically outputting the signals to generate abrasion performances for a sample A and a sample B of the friction pairs; and therefore, the micro-movement friction and abrasion testing machine has the characteristics of being adjustable in vibration excitation amplitude, variable in vibration mode, convenient to operate and move, high in loading precision, and reproducible in project service condition, the experimental data is high in repeatability and can be used for evaluating the micro-movement friction and abrasion performance of a material.

The invention discloses an electronic control beam scanning reflection array antenna and a beam scanning method thereof. The antenna is low in cost and loss and simple in structure. The antenna is characterized in that two initial feed sources are adopted in the antenna to perform irradiation excitation on a reflective array plane, and the excitation amplitude ratio of the feed source 1 to the feed source 2 is changed to change the phase value distribution of a total incident field in the array plane so that electronic control beam scanning can be achieved. The antenna is simple in structure and does not need extra biasing circuits, so that machining is convenient, and stability is high. High-gain beam scanning can be achieved just through the two initial feed sources without extra T/R modules, so that the manufacturing cost is effectively lowered. The antenna is suitable for microwave or millimeter wave or terahertz frequency bands and can be used in wireless communication and radar systems.

The invention provides an array antenna Taylor-Schelkunoff polynomial design method, and relates to a modular array antenna. The method includes the steps that 1, array antenna parameters are selected; 2, the array antenna is divided into at least two modules; 3, a Taylor synthetic method is selected to calculate an array factor directional diagram of the modules; 4, an SPM synthetic method is selected to obtain a directional diagram with null steering, and the null steering angle is made to correspond to the grating lobe angle of the array factor directional diagram; 5, a directional diagram multiplication principle is adopted, the grating lobe of the array factor directional diagram is offset, the low-minor lobe radiation directional diagram is achieved, and the excitation amplitude of all arrays is controlled through the preset null steering angle; 6, if the obtained low-minor lobe radiation directional diagram cannot meet the design requirement, step 2 is executed, and the array antenna is regrouped. According to the array antenna Taylor-Schelkunoff polynomial design method, the excitation amplitude of all the arrays can be controlled through the preset null steering angle, a modular feed network is achieved through an equipower distributor with the phase and impedance being matched, the radiation loss is reduced, and the design and manufacturing cost is lowered.

To simplify designing and fabrication of a shaped beam array antenna for generating a cosecant square beam, slots having the same size are arranged with the same separation on a wall of a wave guide. The slots yield an excitation amplitude distribution wherein the excitation amplitude distribution attenuates exponentially from a feeder side of the wave guide to the terminal side of the wave guide where a terminal dummy is provided. The excitation phase distribution is linear with a slight variation. The first slot nearest to the feeder side is modified to produce an excitation phase difference between the first and the second slot.

The invention discloses a combined optimization method used for synthesizing a large-scale heterogeneous four-dimensional antenna array which employs a pulse phase shift sequence. According to the combined method, a part of convexity of an original synthesis problem is fully utilized, and the original complicated synthesis problem is divided into two sub-problems; and then optimization is performed by two steps: step 1, rapidly optimizing an equivalent excitation amplitude (switch switch-on duration) and a static excitation phase with high efficiency according to constraint of a field at a center frequency by employing a convex optimization algorithm; and step 2, optimizing a switch switch-on initial time with the combination of a subarray optimization technology by employing a differential evolution algorithm according to the requirement of a directional diagram by a sideband so that the whole optimization problem can be rapidly solved with high efficiency. According to the method, the biggest innovation is the discovery of the essential characteristic of the original optimization problem, optimization is performed with the combination of the convex optimization algorithm and the differential evolution algorithm, the speed and the efficiency of the whole optimization process are greatly increased, and the effect of getting double the result with half the effort is achieved.

Methods and apparatus for exciting a structure and determining its structural integrity. In particular, methods of nonlinear analysis are used to compare first and second response datasets, each dataset resulting from a different excitation amplitude that the other dataset.

The invention discloses a synthesis method of an array antenna shaped beam with a controllable excitation amplitude dynamic range, and relates to array antennae. The method comprises the following steps: expressing an array antenna shaped power pattern synthesis problem with the controllable excitation amplitude dynamic range into a mathematical model; introducing an auxiliary variable zeta, performing equality conversion on the constraint of an array excitation amplitude dynamic range ratio, so as to ensure that the constraint of the array excitation amplitude dynamic range ratio is equivalent to the constraint of a square mode on each array element excitation; respectively converting power constraint conditions of a main lobe and a side lobe of a shaped beam into the mode of a trace of a matrix Tr (.), and meanwhile further expressing the DRR constraint of the array element excitation into a constraint mode of a trace of a matrix. As the synthesis problem belongs to a typical nonlinear and nonconvex problem, certain nonconvex constraints are loosened, and meanwhile the looseness is controlled through certain other measures, the nonconvex problem is converted into a convex problem, further a characteristic value decomposition method can be utilized for solving, and finally excitation amplitude distribution meeting requirements is finally obtained.

The invention relates to a method of bridge foundation erosion identification based on vehicle braking impact, belonging to the technical field of bridge pile foundation erosion damage identification.The invention aims at solving the problem that the sensor is easily disturbed by hydrological conditions when placed under water in the existing bridge pier scour monitoring method, and the measurement error is relatively large, and the sensor is liable to be limited by actual environment and climate when installed. The method comprises the steps of: with brake force of the vehicle being used asan exciting source, exciting the acceleration response of the pier in the direction of the bridge, and arranging an acceleration sensor at the top of each pier, taking the acceleration signal collected from the pier top as the analysis signal, obtaining the wavelet packet energy variance of the intact bridge structure and the damaged bridge structure by wavelet packet decomposition and reconstruction, and comparing the wavelet packet energy variance change rate of the intact bridge structure and the damaged bridge structure to determine the damage location and degree. The structural damage identification excitation mode of the invention increases the excitation amplitude, improves the processing precision, and has the advantages of strong real-time performance, simplicity and easy operation, etc.

A method of calculating coefficients determining excitation amplitudes and phases for obtaining a desired antenna pattern of a circular array antenna comprising a plurality of antenna elements disposed circularly. Coefficients for a linear array antenna having the same number of antenna elements as the circular array antenna are determined by a Fourier series expansion in integral limits calculated from a beam direction and a beam width that are estimated from incoming radio waves and then are transformed into the coefficients for the circular array antenna. With this method, the beam direction and the beam width of the antenna pattern of the circular array antenna can be set at will. Consequently, this method enables adaptive control of sectored beams of sectored antennas at a base station or the like used for a mobile communication system, thus enhancing efficiency of the use of the antennas.

The invention provides a power supply ripple interference test method and system. The method comprises the steps of: obtaining preset parameters, carrying out initialization self-checking according to the preset parameters and an excitation parameter and outputting a power supply ripple, wherein the preset parameters comprise a frequency value of the point to be tested and a standard level value corresponding to the frequency value of the point to be tested, and the excitation parameter comprises an excitation amplitude value corresponding to the frequency value of the point to be tested and the standard level output value; and testing the equipment to be tested, and carrying out real-time verification on the power supply ripple. The system comprises an initialization self-checking module and a real-time verification and test module, wherein the initialization self-checking module is used for obtaining the preset parameters, carrying out initialization self-checking according to the preset parameters and the excitation parameter and outputting the power supply ripple; and the real-time verification and test module is used for obtaining the power supply ripple, testing the equipment to be tested, and carrying out real-time verification on the power supply ripple. By adopting the method and system, the testing efficiency and measurement accuracy are effectively improved, therefore, the efficiency and accuracy requirements in a power supply ripple interference test process of automobile electronic equipment are met.

The invention relates to a modal test device. The modal test device comprises a base, a translation mechanism installed on the base, and an excitation mechanism installed on the translation mechanism, wherein the excitation mechanism comprises a vibration exciter and a hammer handle butted with the vibration exciter, the hammer handle is provided with a hammer head, and the hammer head itself is a force sensing element or the hammer head is provided with a force sensing element. The vibration exciter and an elastic reset member control the lifting and falling of the hammer handle so as to control the hammer head to knock a structure or the hammer head to leave the structure. In a plurality of tests, the excitation amplitude generated by the hammer head to the structure is certain, and the repeatability is good. The excitation mechanism is installed on the translation mechanism, the translation mechanism drives the excitation mechanism to move horizontally relative to the base, and the hammering test can be carried out on a plurality of points on the structure by one time of positioning, so that the test is convenient and rapid, and the efficiency is high.

The invention relates to the field of structural damage identification, in particular to a method for identifying structural damage based on a vibration transmissibility function and a support vector machine. The vibration transmissibility function is constructed through an accelerated speed response, the amplitude value of the vibration transmissibility function is used as an analysis signal, all frequency band signals are obtained through wavelet packet decomposition and reconstruction, the energy ENj of all the frequency band signals is obtained through calculation, the variable quantity delta ENj of the energy of the front and rear frequency band signals of the structural damage is used as damage characteristic indexes, and the mode identification function of the support vector machine is used for identifying the structural damage. The method for identifying the structural damage is not influenced by the excitation amplitude value, meanwhile, a structural damage identification method with the problems that a neural network structure is hard to determine and prone to being in local minimization is avoided, operability is strong, processing precision is improved, and the damage identification process is simplified.

The invention provides a near-field sparse antenna array optimization method based on L1 norm constraint, which comprises the following steps: 1. determining the index parameters of the needed near-field sparse antenna array pattern; 2. determining the index parameters of the near-field sparse antenna array pattern. 2, using the L1 norm constraint theory to carry out iterative solution on the array element position and corresponding excitation; 3, normalizing the array excitation obtained by each iteration, and calculating the number of array elements whose excitation amplitude is greater thana given value; 4, judging whether that numb of units of three successive iterations is equal, if equal, the algorithm converges to obtain the final array topology and corresponding excitation. The invention obtains the sparse near-field antenna array topology and corresponding excitation based on the L1 norm minimization. Compared with the traditional method, the sidelobe level is controllable, and the problem of focus shift in the near-field focusing technology is solved at the same time.

The invention provides an axial ratio optimization method of a rotating circular polarization microstrip array antenna in a wide-angle scanning state. By means of the method, the axial ratio of the rotating circular polarization microstrip array antenna in the wide-angle scanning state can be remarkably improved, and a high antenna gain and back lobe level can be achieved. The method includes the steps that an array antenna simulation model is established in simulation software, namely, an HFSS (High Frequency Structure Simulator); simulation calculation is conducted on the array antenna in the wide-angle scanning state, and targeted to any beam pointing, orthogonal electric field data of all array elements in all units is stored and output through a VBscript program; then, a 2*2 sub-array serves as a calculation unit, array element electric field data serves as the basis, and the excitation amplitude and the excitation phase actually required by all the array elements in all the units meeting the circular polarization condition are calculated through a MATLAB (matrix laboratory) program; an HFSS simulation data processing module directly loads the excitation amplitude and the excitation phase actually required by all the units and stored and output by the MATLAB to conduct simulation calculation again, and axial ratio optimization is achieved.

Methods for fragmenting ions retained in an ion trap are described. In various embodiments, a non-steady-state pressure of a neutral collision gas of less than about 5×10⁻⁴ Torr and an excitation amplitude of less than about 500 mV (peak to ground) is used to fragment ions with greater than about 80% fragmentation efficiency. In various embodiments, duration of ion excitation is greater than about 25 ms.

The invention discloses a random bit programmable meta-material design method based on space-time coding; the method comprises the specific steps: 1, designing a coding unit with a low bit, arrangingin a spatial period to form a two dimension programmable meta-material, wherein each unit structure is integrated with one or more active device, and the unit can present different electromagnetic responses under a digital control module; 2, giving a set of independent time coding sequence to each unit, and periodically cycling to form an equivalent excitation amplitude and phase, thus realizing random high bit responses; 3, designing a corresponding space-time three dimensional coding matrix, and calculating the space scattering energy of the meta-material at different harmonic frequencies, thus satisfying specific application demands. The method can solve the problems that a conventional programmable meta-material is hard to realize high bit designs, thus simplifying a control circuit and a feed network, and saving active devices.