Time domain signal reproduction conversion method and device of impact response spectrum, and medium

Abstract

The invention discloses a time domain signal reproduction conversion method and device of an impact response spectrum and a medium. Belongs to the field of impact mechanical environment related design and test, and particularly belongs to the technical field of time domain signal reproduction of an impact response spectrum. The technical problem that the real time domain energy distribution condition of the time domain waveform corresponding to the impact response spectrum cannot be fully reflected in the prior art is solved. In the fundamental wave amplitude modulation, a Weibull sine window is adopted to process sine wavelets, and the time domain peak position and the decay time can be adjusted by utilizing the characteristic that a Weibull distribution function curve can change according to parameter adjustment. And waveform adjustment is realized by using a sine function, and the low-error convergence capability of the time domain waveform impact response spectrum is improved. Error control of the impact response spectrum of the reproduced time domain signal and the target impact response spectrum is superior to + / -2dB, parameterization control is carried out on the time domain waveform peak position and the decay time, and the distribution condition of impact energy under the time domain and frequency domain conditions is effectively reproduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of impact mechanics environment related design and test, in particular to the field of time domain signal reproduction of impact response spectrum. BACKGROUND

[0002] Impact environment is one of the main reasons for the failure of key instruments and devices or components on spacecraft. At present, in the design stage of spacecraft products, impact response spectrum test is usually used to examine the anti-impact ability of the products, and the impact response spectrum is the maximum response envelope curve of a series of single degree of freedom systems with different natural frequencies subjected to time domain vibration. Since there is a "one-to-many" phenomenon when the impact response spectrum is converted into a time domain impact signal, that is, there is a difference in the time sequence of the impact signal obtained by different time domain conversion methods, which is the main reason for under-test or over-test. Therefore, when the impact response spectrum is converted into a time domain signal, the time domain and frequency domain characteristics of the impact condition should be considered at the same time, so as to improve the rationality of the impact condition conversion.

[0003] In the synthesis method of impact response spectrum time domain waveform, a limited number of specified frequency amplitude-modulated sine waves (wavelets) are usually superimposed, that is, the wavelet synthesis method. The base wave amplitude modulation methods used include sine window base wave, hanning window base wave, decaying sine window base wave, rectangular window base wave, etc. Generally, the decaying sine window base wave is used as the base wave function of the time domain signal with decaying characteristics. However, since the window function performs exponential decay processing on the time domain curve, the time domain curve obtained after conversion lacks the response rising segment in the initial stage of impact, so the existing technology has the problem of missing the response rising time in the initial stage of impact. At the same time, there is the problem of insufficient energy decay, too fast high-frequency decay and too slow low-frequency decay, which cannot fully reflect the real time domain energy distribution of the time domain waveform corresponding to the impact response spectrum. SUMMARY

[0004] In view of the technical problem in the prior art that the real time domain energy distribution of the time domain waveform corresponding to the impact response spectrum cannot be fully reflected, the present application provides a time domain signal reproduction conversion method of impact response spectrum.

[0005] The method comprises the following steps:

[0006] S1, obtaining the related parameters of the target impact response spectrum, setting the target peak time t p and the tolerance δ p , setting the decay end time t e and the tolerance δ e ;

[0007] S2, initializing the impact spectrum parameters and time domain waveform parameters of the sine base wave;

[0008] S3, synthesizing the time domain waveform x(t) of the sine base wave by using the Weibull sine window.

[0009] S4. Obtain the peak time t' of the current time-domain impulse signal based on the synthesized time-domain waveform x(t). p and the current time-domain impulse signal decay end time t e ′, and with the target peak time t p Attenuation end time t e For comparison, if the time difference is greater than the allowable tolerance δ p and δ e Then adjust the time-domain waveform parameters until the time difference is less than the allowable tolerance δ. p and δ e At this point, the first time-domain impact signal is obtained;

[0010] S5. The first time-domain impulse signal is converted using a digital filtering method to obtain the first impulse response spectrum. The upper and lower limits of the target spectrum are compared with the first impulse response spectrum. If the first impulse response spectrum is at frequency f... i If the value exceeds the upper or lower limit, the amplitude of the sinusoidal fundamental wave is corrected and the second time-domain impact signal and the second impact response spectrum are calculated. The upper or lower limit is then determined again, and the correction is iterated in the above manner until the final impact response spectrum is within the range of the upper and lower limits of the target impact response spectrum, thus obtaining the final time-domain waveform.

[0011] In steps S6 and S5, if the number of iterations exceeds the preset number, but the impact response spectrum is still not within the upper and lower limits of the target impact response spectrum, then the time-domain impact signal is subjected to zero-phase offset band-stop filtering to make the final impact response spectrum within the upper and lower limits of the target impact response spectrum, thus obtaining the final time-domain waveform.

[0012] Furthermore, relevant parameters are obtained through the target impact response spectrum, including the initial frequency f. s Termination frequency f e Inflection point frequency f m The slope s of the rising segment of the impact spectrum and the amplitude A of the impact response spectrum srs .

[0013] Furthermore, the impulse spectrum parameters of the sinusoidal fundamental wave include the fundamental wave amplitude, the fundamental wave waveform delay time, and the quality factor Q, while the time-domain waveform parameters include the shape parameter k and the scale parameter λ.

[0014] Furthermore, the time-domain waveform x(t) synthesized from the sinusoidal fundamental wave is obtained by using a Weibull sine window through:

[0015] Achieve, where n represents the total number of fundamental frequencies, A i f is the waveform amplitude of the i-th fundamental wave. i Let t be the waveform frequency of the i-th fundamental wave. diis the waveform delay time of the i-th base wave relative to the zero time, N i is the number of waveform half-sine waves of the i-th base wave.

[0016] Further, when adjusting the time-domain waveform parameters, the influence of the shape parameter k on the current time-domain waveform x(t) is as follows: when the shape parameter k=1, it degenerates into an exponential distribution, when 0

[0017] Further, when adjusting the time-domain waveform parameters, the influence of the scale parameter λ on the current time-domain waveform x(t) is as follows: the scale parameter λ>0, adjusting the value can determine the attenuation degree of the curve, i.e. the width of the distribution; increasing the value of λ makes the distribution more concentrated, and decreasing the value of λ makes the distribution more dispersed.

[0018] Further, the correction of the amplitude of the sine base wave is performed by: , wherein A' i represents the amplitude of the waveform of the i-th base wave after correction, A srsi represents the value of the target shock response spectrum at the i-th frequency, y i represents the value of the shock response spectrum at the i-th frequency, A' i represents the amplitude of the waveform of the i-th base wave after correction.

[0019] The method has the following beneficial effects:

[0020] (1) In the present application, the base wave amplitude modulation adopts Weibull sine window to process the sine wavelet, and the curve of the Weibull distribution function can be adjusted according to the parameter to change the characteristics of the time-domain peak position and the decay time. The sine function is used to adjust the waveform, which improves the low-error convergence ability of the time-domain waveform shock response spectrum.

[0021] (2) The error of the reproduced time-domain signal shock response spectrum and the target shock response spectrum can be controlled to be better than ±2dB, and the peak position and decay time of the time-domain waveform are parameterized controlled, which effectively reproduces the distribution of the shock energy under the conditions of time domain and frequency domain. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 is a flow chart of the time-domain signal reproduction conversion method of the shock response spectrum;

[0023] Figure 2 is an example schematic diagram of the target shock response spectrum;

[0024] Figure 3 is the time-domain graph of the actual shock environment;

[0025] Figure 4 is the shock response spectrum graph of the actual shock environment;

[0026] Figure 5 is the time-domain and frequency-domain energy distribution graph of the actual shock environment;

[0027] Figure 6 is the time-domain graph of the Weibull sine window fundamental wave synthesis (k = 0.4, λ = 2.5 x 10 -4 );

[0028] Figure 7 is the shock response spectrum graph of the Weibull sine window fundamental wave synthesis time-domain graph (k = 0.4, λ = 2.5 x 10 -4 );

[0029] Figure 8 is the time-domain and frequency-domain energy distribution graph of the Weibull sine window fundamental wave synthesis time-domain graph (k = 0.4, λ = 2.5 x 10 -4 ). DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be described clearly and completely below in conjunction with the drawings. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0031] Embodiment 1,

[0032] In this embodiment, the fundamental wave amplitude modulation adopts the Weibull sine window to process the sine wavelet, and the Weibull distribution function curve can be adjusted according to the parameter to change the characteristics of the time-domain peak position and the decay time. The sine function is used to adjust the waveform, and the low-error convergence ability of the time-domain waveform shock response spectrum is improved.

[0033] The Weibull sine window formula for synthesizing the sine fundamental wave is as follows:

[0034]

[0035] In the formula, A i is the waveform amplitude of the i-th fundamental wave, f i is the waveform frequency of the i-th fundamental wave, t di is the waveform delay time of the i-th fundamental wave relative to zero time, N i is the number of half-sine waves of the i-th fundamental wave, k is the shape parameter, and λ is the scale parameter.

[0036] When the shape parameter k = 1, it degenerates into an exponential distribution. When 0 < k < 1, the early curve slope changes rapidly, and the rate of change of the slope gradually decreases over time. When k > 1, it is a right-biased distribution, and the distribution gradually tends to be symmetrical as k increases. When k = 1.5, the curve distribution is approximately a lognormal distribution; when k = 2.0, it is close to a Lévy distribution; and when k = 3.4, it is close to a normal distribution. The greater the value of k, the more energy there is in the tail of the distribution. The scale parameter λ > 0, and adjusting this value can determine the degree of attenuation of the curve, i.e., the width of the distribution; a larger λ value makes the distribution more concentrated, and a smaller λ value makes the distribution more dispersed.

[0037] After using the fundamental wave of the Weibull sine window to synthesize a first time-domain shock signal for the target shock response spectrum, a first shock response spectrum is converted using a digital filtering method for the first time-domain shock signal. The upper limit curve of the target shock response spectrum and the lower limit curve of the target shock response spectrum are compared with the first shock response spectrum, respectively. If the first shock response spectrum exceeds the upper and lower limit values at frequency f i , the fundamental wave amplitude is corrected using the following formula, and a second time-domain signal and a second shock response spectrum are calculated. The iteration correction is continued to make the final shock response spectrum within the upper and lower limit ranges of the target shock response spectrum.

[0038] Correction formula:

[0039] In the formula, A srsi is the value of the target shock response spectrum at the i th frequency, y i is the value of the shock response spectrum at the i th frequency, and A' i is the corrected waveform amplitude of the i th fundamental wave.

[0040] If there are multiple iterations of shock response spectrum local frequency bands that still cannot converge, zero-phase offset band-stop filtering is performed on the time-domain shock signal, so that the shock response spectrum corresponding to the fitted time-domain curve converges quickly.

[0041] While the shock response spectrum value is iteratively corrected, the shape parameter k and the scale parameter λ are adjusted according to the target peak time t p and the decay end time t e to adjust the time-domain shock signal. The allowable difference between the two times is δ p and δ e . When the difference between the peak time t' p of the time-domain shock signal and t p exceeds δ p , k is adjusted. When k decreases, the peak time moves forward, and when k increases, the peak time moves backward. When the decay end time t e ' of the time-domain shock signal and t ethe difference between them exceeds δ e , the end time of decay moves backward when λ decreases, and moves forward when λ increases.

[0042] The iteration termination criterion is that the time-domain signal corresponding to the shock response spectrum is between the upper and lower limits of the target spectrum, the difference between the time-domain peak time and the target peak time is within δ p , and the difference between the time-domain decay end time and the target decay end time is within δ e .

[0043] Embodiment 2,

[0044] This embodiment is a further limitation of embodiment 1, as Figure 1 The time-domain signal reproduction conversion method flow chart of the shock response spectrum is shown. According to the target shock response spectrum, the starting frequency f s , the ending frequency f e , the inflection point frequency f m , the shock spectrum rising slope s, the shock response spectrum amplitude A srs , the waveform duration T c , the peak time t p , the tolerance δ p , the decay end time t e , and the tolerance δ e , and the quality factor Q = 10 are obtained. The waveform amplitude A i of the fundamental wave, the fundamental waveform delay time t di , and the shape parameter k are initialized, and λ is the scale parameter. The sine fundamental wave is synthesized into a time-domain waveform x(t) using a Weibull sine window, wherein the basic waveform is obtained according to the calculation formula:

[0045] Then the synthesized time-domain waveform formula is as follows:

[0046]

[0047] According to the synthesized time-domain waveform, the current time-domain shock signal peak time t p ′ and the current time-domain shock signal decay end time t e ′ are obtained, and compared with the target peak time t p , the decay end time t e , if the time difference is greater than the tolerance δ p and δ e , adjust the shape parameter k and the scale parameter λ.

[0048] The shape parameter k adjustment strategy is as follows:

[0049] When 0 < k < 1, the early curve slope changes rapidly, and the slope gradually decreases over time. When k > 1, it is a right-biased distribution, and the distribution gradually tends to be symmetrical as k increases. When k = 1.5, the curve distribution is approximately lognormal. When k = 3.4, it is close to normal distribution. The smaller the value of k, the more energy the initial segment of the distribution has. When the shape parameter k = 1, it degenerates into an exponential distribution.

[0050] The scale parameter λ is adjusted as follows:

[0051] The scale parameter takes λ > 0, and adjusting this value can determine the degree of attenuation of the curve. λ affects the width of the distribution. A larger λ value makes the distribution more concentrated, while a smaller λ value makes the distribution more dispersed.

[0052] After using the fundamental wave of the Weibull sine window to synthesize the first time-domain shock signal for the target shock response spectrum, the first time-domain shock signal is converted to obtain the first shock response spectrum using the improved digital filtering method. The upper limit and the lower limit of the target spectrum are compared with the first shock response spectrum, respectively. If the first shock response spectrum exceeds the upper limit value or the lower limit value at frequency f i , the fundamental wave amplitude is corrected, and the second time-domain signal and the second shock response spectrum are calculated. The iteration is continued until the final shock response spectrum is within the upper and lower limits of the target shock response spectrum.

[0053] If there are multiple iterations of shock response spectrum local frequency bands that still cannot converge, zero-phase offset band-stop filtering is performed on the time-domain shock signal, so that the shock response spectrum corresponding to the fitted time-domain curve converges quickly.

[0054] After the time-domain signal meets the following conditions, the loop is ended to obtain the final time-domain waveform: the shock response spectrum corresponding to the time-domain signal is between the upper and lower limits of the target shock response spectrum, the difference between the time-domain peak time and the target peak time is within δ p , and the difference between the time-domain decay end time and the target decay end time is within δ e .

[0055] The technical method of the embodiment will be described in detail below through a specific test data.

[0056] The target shock response spectrum has a starting frequency f s = 100 Hz, a terminal frequency f e = 5000 Hz, an inflection point frequency f m = 1000 Hz, a shock spectrum rising slope s = 8, a shock response spectrum amplitude A srs = 1000 g, a shock response spectrum upper and lower limit of ± 2 dB, and a maximum number of shock spectrum iterations of 10 times. The target shock response spectrum is shown in Figure 2 . Take t p = 1 ms, te = 15 ms, δ p = 0.2 ms, δ e = 2 ms, when k = 0.4, λ = 2.5 x 10 -4 When the 2nd order zero-phase band-stop attenuation filter is used for the 100 Hz-300 Hz frequency band, the time-domain curve is shown in Figure 6 , the shock response spectrum is shown in Figure 7 , and the energy distribution in the time domain and frequency domain is shown in Figure 8 . At this time, the time-domain curve and the shock response spectrum both meet the requirements, and the final time-domain result is obtained. Figure 3 、 Figure 4 、 Figure 5 The time-domain curve, the shock response spectrum, and the energy distribution diagram under the actual measured shock environment are shown in Figure 3 and Figure 6 . It can be seen that the two time-domain curves are basically consistent, with a detailed rising section and an exponential decay section. Comparing Figure 4 and Figure 5 , it can be seen that the two shock response spectra are basically consistent and can both represent the maximum 1000g shock condition. Comparing Figure 5 and Figure 8 , it can be seen that the time-domain waveform reproduced by the method can basically restore the time-domain and frequency-domain energy distribution of the shock environment.

[0057] Example 3,

[0058] The memory in the embodiments of the present application can be a volatile memory or a nonvolatile memory, or can include both volatile and nonvolatile memory. Among them, the nonvolatile memory can be a read only memory (ROM), a programmable ROM (PROM), an erasable programmable ROM (EPROM), an electrically EPROM (EEPROM), or a flash memory. The volatile memory can be a random access memory (RAM) used as an external cache. By way of example, and not limitation, many forms of RAM can be used, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous dynamic RAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchlink DRAM (SLDRAM), and direct rambus RAM (DR RAM). It is to be noted that the memory described with the methods of the present application is intended to include, but not be limited to, these and any other suitable types of memory.

[0059] In the above embodiments, all or part of the embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, all or part of the embodiments can be implemented in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer instructions are loaded and executed on a computer, all or part of the processes or functions described in the embodiments of the present application are generated. The computer can be a general-purpose computer, a special-purpose computer, a computer network or other programmable apparatus. The computer instructions can be stored in a computer-readable storage medium or transmitted from one computer-readable storage medium to another computer-readable storage medium, for example, the computer instructions can be transmitted from one website, computer, server or data center to another website, computer, server or data center through wired (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (such as infrared, wireless, microwave, etc.) mode. The computer-readable storage medium can be any available medium that can be accessed by a computer or a data storage device such as a server, data center, etc. containing one or more available media sets. The available media can be magnetic media (such as floppy disk, hard disk, magnetic tape), optical media (such as high-density digital video disc (digital video disc, DVD)), or semiconductor media (such as solid state disc (solid state disc, SSD)) and the like.

[0060] In the implementation process, each step of the above method can be completed by the integrated logic circuit of hardware in the processor or the instruction in the form of software. The steps of the method disclosed in the embodiments of the present application can be directly embodied as hardware processor execution completion, or executed by hardware and software modules in the processor. The software module can be located in a mature storage medium in the field, such as random access memory, flash memory, read-only memory, programmable read-only memory, electrically erasable programmable memory, register, etc. The storage medium is located in the memory, and the processor reads the information in the memory, and combines the hardware to complete the steps of the above method. To avoid repetition, it will not be described in detail here.

[0061] It should be noted that the processor in the embodiments of the present application can be an integrated circuit chip with signal processing capability. In the implementation process, each step of the above method embodiment can be completed by the integrated logic circuit of hardware in the processor or the instruction in the form of software. The processor described above can be a general-purpose processor, a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic device, a discrete hardware component. The processor can implement or execute the procedures or functions in the embodiments of the present application.

[0062] The disclosed methods, steps and logic block diagrams in the embodiments. The general processor can be a microprocessor or the processor can also be any conventional processor or the like. In conjunction with the embodiments of the present application

[0063] The disclosed methods, steps and logic block diagrams in the embodiments. The general processor can be a microprocessor or the processor can also be any conventional processor or the like. In conjunction with the embodiments of the present application

[0064] The disclosed methods, steps and logic block diagrams in the embodiments. The general processor can be a microprocessor or the processor can also be any conventional processor or the like. In conjunction with the embodiments of the present application

[0065] The disclosed methods, steps and logic block diagrams in the embodiments. The general processor can be a microprocessor or the processor can also be any conventional processor or the like. In conjunction with the embodiments of the present application

[0066] The disclosed methods, steps and logic block diagrams in the embodiments. The general processor can be a microprocessor or the processor can also be any conventional processor or the like. In conjunction with the embodiments of the present application

[0067] The disclosed methods, steps and logic block diagrams in the embodiments. The general processor can be a microprocessor or the processor can also be any conventional processor or the like. In conjunction with the embodiments of the present application

[0068] The disclosed methods, steps and logic block diagrams in the embodiments. The general processor can be a microprocessor or the processor can also be any conventional processor or the like. In conjunction with the embodiments of the present application

Claims

1. A time-domain signal reproduction conversion method of an impact response spectrum, characterized by, The method comprises the following steps: S1, obtain the relevant parameters of the target impact response spectrum, set the target peak time t p and tolerance δ p , set the end time t e of the attenuation and tolerance δ e ; S2, initializing the shock spectrum parameters and time-domain waveform parameters of the sinusoidal base wave; S3, synthesizing the time-domain waveform x(t) of the sinusoidal base wave by using a Weibull sinusoidal window; S4, obtaining current time-domain shock signal peak time t' p and current time-domain shock signal decay end time t' e , and comparing with target peak time t p , decay end time t e , if time difference is greater than tolerance δ p and δ e , adjusting time-domain waveform parameters until time difference is less than tolerance δ p and δ e , and obtaining first time-domain shock signal. S5, using a digital filtering method to convert the first time-domain shock signal to obtain a first shock response spectrum, using the target spectrum upper limit and the target spectrum lower limit to compare with the first shock response spectrum respectively, if the first shock response spectrum exceeds the upper limit value or the lower limit value at frequency f i , the sine fundamental amplitude is corrected and the second time-domain shock signal and the second shock response spectrum are calculated, it is continued to judge whether it exceeds the upper limit value or the lower limit value, and the above-mentioned mode is iteratively corrected until the final shock response spectrum is within the range of the upper limit value and the lower limit value of the target shock response spectrum, and the final time-domain waveform is obtained. S6, in step S5, if the iteration exceeds the preset number of times, but the shock response spectrum is still not within the upper limit value and the lower limit value range of the target shock response spectrum, then the time-domain shock signal is processed by zero-phase offset band-stop filtering, so that the final shock response spectrum is within the upper limit value and the lower limit value range of the target shock response spectrum, and the final time-domain waveform is obtained.

2. The impact response spectrum time-domain signal reproduction conversion method according to claim 1, characterized by, By target impact response spectrum, its related parameters are acquired, including acquiring starting frequency f s , terminal frequency f e , inflection point frequency f m , impact spectrum rising section slope s and impact response spectrum amplitude A srs .

3. The impact response spectrum time-domain signal reproduction conversion method according to claim 2, characterized by, The shock spectrum parameters of the sinusoidal base wave include the waveform amplitude, the waveform delay time and the quality factor Q of the base wave, and the time-domain waveform parameters include the shape parameter k and the scale parameter λ.

4. The impact response spectrum time-domain signal reproduction conversion method according to claim 3, characterized by, The time-domain waveform x(t) is synthesized by using a Weibull sine window on a sine fundamental wave through: Implementation, where n represents the total number of fundamental waves, A i is the waveform amplitude of the i-th fundamental wave, f i is the waveform frequency of the i-th fundamental wave, t di is the waveform delay time of the i-th fundamental wave relative to the zero time, N i is the number of waveform half-sine waves of the i-th fundamental wave.

5. The impact response spectrum time-domain signal reproduction conversion method according to claim 4, characterized by, When adjusting the time-domain waveform parameters, the influence of the shape parameter k on the current time-domain waveform x(t) is as follows: when the shape parameter k=1, it degenerates into an exponential distribution; when 0 6. The impact response spectrum time-domain signal reproduction conversion method according to claim 5, characterized by, When adjusting the time-domain waveform parameters, the influence of the scale parameter λ on the current time-domain waveform x(t) is as follows: the scale parameter λ>0, adjusting the value can determine the attenuation degree of the curve, that is, the width of the distribution; increasing the value of λ makes the distribution more concentrated, and decreasing the value of λ makes the distribution more dispersed.

7. The impact response spectrum time-domain signal reproduction conversion method according to claim 6, characterized by, The amplitude of the sine base wave is corrected by: where A ′ i denotes the amplitude of the i-th base wave after correction, A srsi denotes the value of the target shock response spectrum at the i-th frequency, y i denotes the value of the shock response spectrum at the i-th frequency, A ′ i denotes the amplitude of the i-th base wave after correction. 8.An electronic device comprising a memory and a processor, the memory storing a computer program, wherein, The processor implements the steps of the method of any one of claims 1-7 when executing the computer program.

9. A computer readable storage medium for storing computer instructions, characterized in that, The computer instructions implement the steps of the method of any one of claims 1-7 when executed by the processor.

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