110 results about "Pulse spectrum" patented technology

This invention refers to a method and device for measuring super short laser pulse, which adopts different optical structure with traditional Spectral Phase Interferometry for Direct Electric-field Reconstruction (SPIDER), sum-frequency of the copy pulse of a pulse to be measured with two quasi-monochrome long pulses with different frequency to generate two frequency spectrum sheared sum-frequency, leading defined small time delay between said two pulses through piezoelectric driven single reflection mirror or step reflection mirror, combined with measured single sum-frequency spectrum to calculate point-to-point spectrum phase difference of pulse to be measured, then reconstructing pulse spectrum phase without using Fourier transformation filter process.

The invention relates to a new method for measuring an ultrashort light pulse spectral phase in the field of information optoelectronics and a device thereof. According to the method, a time delay minus T with polarity is introduced between two quasi-monochromatic light components with frequency Omega generated by the chirped stretching of a pulse to be detected; an additional time delay plus T, which is introduced between two quasi-monochromatic light components due to a pulse stretcher, is compensated to be in synchronization with the pulse to be measured and generate two sum frequency lights together with the pulse through a sum frequency crystal; respective power spectra and coherent spectra without interference fringe are acquired through a spectrometer. The phase difference between the two sum frequency lights is calculated by the three spectra through formulae. A spectrum phase curve of the pulse to be measured is calculated by adopting a concatenated method. The method can accurately determine the phase difference polarity of the pulse spectrum, and provide the simple, real-time, rapid and accurate measurement method and the device thereof for measuring the ultrashort optical pulse spectral phase.

The invention relates to an optical signal technology physical method for preserving vegetables and fruits and an optical signal generating device. By adopting a computer programmable pulse scanning signal generator, the invention controls a light-emitting device with a red, green and blue light source pack to generate a pulse-type optical signal or an optical signal of a pulse-type periodical scanning combined spectrum so as to illuminate fresh vegetables and fruits stored in a storage device under a room-temperature storage condition or a temperature and moisture control condition. Under the physical environmental condition of an artificial optical signal, the illuminated fresh vegetables and fruits obtain photon energy needed for an optical reaction in photosynthesis in an optical signal illumination environment with periodical brightness change so that cell tissues recover metabolism and maintain the slow operation of metabolism and growth inertia; through controlling the optical signal of a periodical pulse spectrum or a periodical pulse scanning spectrum or a periodical pulse scanning combined spectrum, and the illuminance, the pulse period and the combined scanning mode of a visible spectrum optical signal emitted by the red, green and blue light source pack are controllable so as to achieve the aims of controlling the slow growth process of the harvested vegetables and fruits under the room-temperature condition or the temperature and moisture control condition, effectively prolonging the fresh state of the harvested vegetables and fruits by the slow metabolism operation of the preserved vegetables and fruits, keeping the freshness of the stored vegetables and fruits and prolonging the preservation time.

The invention discloses a frictional torque compensation method and device as well as an idle speed control method and system and belongs to the field of automobile electronic control. The frictional torque compensation method comprises the following steps: inquiring an initial frictional torque from a prestored torque pulse spectrum table according to the current engine operating parameter; carrying out double integration on the D-value of the current revolving speed and a target revolving speed to obtain a frictional torque compensation value; and adding the initial frictional torque and the frictional torque compensation value together to obtain a final frictional torque. The frictional torque compensation system realizes the frictional torque compensation method, and the idle speed control method and an idle speed control system utilize the final frictional torque acquired by the compensation to carry out idle speed control; the D-value of the current revolving speed and the target revolving speed is subjected to double integration so as to obtain the frictional torque compensation value, thereby effectively reducing or eliminating the difference of the frictional torque obtained through searching the table and the actual frictional torque of an engine; and the final frictional torque after compensation is utilized to realize more stable idle speed control.

The invention relates to an all-optical quantification system and an all-optical quantification method based on dynamic spectrum compression. The all-optical quantification system comprises a high-nonlinearity optical fiber for converting an optical signal subjected to all-optical sampling into an optical pulse signal subjected to frequency shifting, a dynamic power equilibrium unit for performing power equilibrium on optical pulses with different wavelengths of the optical pulse signal and acquiring an optical pulse signal subjected to power equilibrium, a comb-shaped optical fiber for performing spectrum compression on the optical pulse signal subjected to power equilibrium and thus acquiring an optical signal subjected to spectrum compression, and a dispersion element for performing space separation on the signal subjected to spectrum compression and thus acquiring an quantified signal, wherein the high-nonlinearity optical fiber, the dynamic power equilibrium unit, the comb-shaped optical fiber and the dispersion element are sequentially connected. The all-optical quantification system has the advantages that the shortcomings of three pulse spectrum compression methods in the background technology are effectively overcome, the all-optical qualification precision is also improved, and the complexity of the all-optical quantification system based on soliton self frequency shifting (SSFS) is reduced; and the blank of a dynamic power control part in an all-optical analog to digital converter (ADC) is made up.

A chirped-pulse fiber amplification method and system operates with large nonlinear phase shifts (as large as ˜20π or more). In this regime, the pulse spectrum is modified by strong self-phase modulation and gain shaping. With large-enough nonlinear phase shift, substantial spectral broadening occurs. The amplified spectrum can therefore be much broader than the spectrum that is obtained with small nonlinear phase shifts. The broader spectrum enables the formation of a shorter pulse, and the bandwidth generated in nonlinear chirped-pulse amplification can in fact be exploited to generate shorter pulses. Ultimately, this allows the generation of pulses shorter than the gain-narrowing limit of a fiber amplifier.

The invention provides an oil injection timing control system aiming at a double-swirl combustion system and a control policy thereof. The invention has the advantages that fuel jets under different working conditions and a double-swirl combustion chamber 2 are matched and optimized by using a modern precise control technology, and an oil injection advance angle is exactly controlled; under an idle speed and a small load, an injection starting point is a function of the oil injection quantity and the rotating speed of the diesel engine and is obtained through a demarcated pulse spectrum, and under a large load, the injection starting point is commonly decided by the rotate speed of an engine, in-cylinder pressure and injection pressure; at the moment, a fuel oil bundle passes through an arc ridge, and is split into two parts and distributed to an inner chamber and an outer chamber in a best proportion; double swirls are formed so as to more quickly form uniform combustible mixing gas and ensure that combustion is quick and perfect without large inlet vortex flows; and the economical and dynamic indexes of the engine are improved, and the discharge of harmful pollutants can be reduced.

The invention provides a variable supercharged engine EGR rate feedback control method based on air inlet flowmeter information. The method comprises the steps that 1, a standard air inlet flow pulse spectrum and a target EGR rate pulse spectrum are queried to obtain standard air inlet flow and target EGR rate; 2, an EGR valve basic-opening-degree pulse spectrum is queried to obtain an EGR valve opening degree base value; 3, the target inlet flow of fresh air of an engine is calculated, the actual air inlet flow of the fresh air of the engine is measured, and an air inlet flow deviation of the fresh air of the engine is calculated; 4, an EGR valve correction opening degree pulse spectrum is queried to obtain an EGR valve opening degree correction value; 5, the sum of the EGR valve opening degree base value and the EGR valve opening degree correction value is an EGR valve opening degree target value; 6, an actual EGR valve opening degree value is measured and is regulated by using an EGR valve PID controller to make the actual value consistent to the EGR valve opening degree target value. By adopting the method, the consistency between the actual EGR rate and the target EGR rate is ensured on the basis that rapid responsiveness of an EGR system is ensured.

The invention discloses an all-optical-fiber sub-hundred-femtosecond ultrashort pulse generation apparatus with a compact structure. The apparatus comprises a dissipation soliton oscillator, an output isolation part, a pre-compression part and an amplifying and nonlinear compression part which are connected in sequence through mono-mode optical fibers; negative dispersion is introduced to the pre-compression part; the negative chirp quantity provided by the pre-compression part is less than the positive chirp quantity of input pulse; the dissipation soliton oscillator generates pulse with relatively high energy and positive chirp, and the pulse enters the pre-compression part through the output isolation part to compress the pulse width and improve the pulse peak power, and finally, the pulse energy in the amplifying and nonlinear compression part is improved; and the pulse spectrum is widened and the pulse width is compressed through the nonlinear process to obtain the sub-hundred-femtosecond ultrashort pulse. The apparatus has the all-optical-fibre structure and relatively high resistance to external environment disturbance based on a dissipation soliton optical fibre laser in a single-wall carbon nanotube locking mode and can stably output sub-hundred-femtosecond pulse for a long time.

The invention discloses a laser diode pumping Kerr-lens mode locking Yb:(YLa)2O3 all-solid-state femtosecond laser device. Yb:(YLa)2O3 laser ceramics, a pumping source, an optical coupling focusing system, two concave mirrors, two triple prisms, a GTI reflecting mirror, a plane mirror and an output mirror are arranged. According to the device, Kerr-lens mode locking is achieved on the Yb:(YLa)2O3 laser ceramics at the first time, 170 fs of mode locking pulses are output, the half-width of a mode-locking pulse spectrum is 7.7 nm, and the average output power is 140 mW. The device has the advantages of being good in practicability and operability, compact, small and exquisite in structure, suitable for repeated production and assembling, and mass production and lower in cost, achieving single-way laser output, high repetition frequency and femtosecond magnitude pulse width, and being high in stability and light beam quality, can be widely applied to the fields of national defense, industries, medical treatment and scientific research, and has the good application prospects and commercial value.

The invention relates to a method for generating and detecting terahertz pulses in real time. According to the technical scheme, the method comprises the steps that a metallic vapor vacuum arc method is carried out on lithium niobate single crystals grown through a crystal pulling method to obtain a lithium niobate single crystal sheet with copper injected, and the lithium niobate single crystal sheet is used as a terahertz radiation source (5); laser pulses generated by a titanium sapphire laser (3) enter the terahertz radiation source (5) in an incident mode, and terahertz pulses are generated through an optical rectification method; a terahertz time-domain pulse spectrum is obtained through an electro-optical sampling method, and finally fast Fourier transformation is carried out on the terahertz time-domain pulse spectrum through MatLab software installed in a computer to obtain a terahertz frequency-domain pulse spectrum. The method has the advantages that the device is simple, cost is low, the raw materials of the terahertz radiation source are rich and easy to obtain, and the terahertz pulses are high in generation efficiency.

A physical method for maintaining the freshness of vegetables and fruits via the technology of the optical signal and optical signal generator are disclosed. By adopting the computer programmable pulsed scanning signal generator, it controls the light-emitting device mounted with red, green and blue light sources group to generate optical signal with pulsed or pulsed periodical scanning combined spectrum. The optical signal irradiates the fresh-cut fruits and vegetables preserved in the storage assembly at room temperature or at controlled temperature and humidity. By regulating the optical signal with periodical pulsed spectrum or pulsed scanning spectrum or periodical pulsed scanning combined spectrum, the irradiated vegetables and fruits obtain photon energy needed in light reactions of photosynthesis from the lighting environment of artificial optical signal which is in bright and dark periodic variation. The metabolism of the cellular tissue is thus recovered and maintained, and the growth inertia is kept at slow speed. It effectively prolongs the freshness state of vegetables and fruits which are preserved in the storage assembly.

The invention discloses a method for improving drivability of a finished vehicle. Corresponding throttle torque pulse spectrums are achieved by the finished vehicle according to different gears, thusthe different gears correspond to the different throttle torque pulse spectrums, and the corresponding throttle torque pulse spectrum is selected according to the current gear to control the engine running area of the finished vehicle. The method for improving drivability of the finished vehicle is economical, specifically, the corresponding throttle torque pulse spectrums are achieved according to the different gears, the engine running area can be controlled, and the high fuel consumption area on the universal characteristics are avoided to achieve the fuel saving purpose. The method for improving drivability of the finished vehicle has excellent emission performance, specifically, the corresponding throttle torque pulse spectrums are achieved according to the different gears, the enginerunning area can be controlled, and the high emission area on the universal characteristics are avoided to achieve the purpose of controlling emission.

The invention provides a phase-sensitive optical time domain reflection device and method based on frequency modulation. The method comprises the following steps: dividing laser into two paths, carrying out the synchronous modulation and output of an intensity modulator, obtaining a multi-frequency optical pulse sequence, wherein each optical pulse spectrum is composed of a fixed single frequency and a linear chirp with a non-overlapping frequency band; enabling the sequence to generate backward Rayleigh scattering signals with mutually separated frequency bands in a sensing optical fiber, and obtaining a Rayleigh scattering pattern of each multi-frequency optical pulse by using digital band-pass filters with different frequency bands; and sequentially carrying out related processing on the Rayleigh scattering patterns obtained in sequence, and finally obtaining a disturbance position and a disturbance size thereof. According to the phase-sensitive optical time domain reflection device and method based on frequency modulation provided by the invention, the problem of signal aliasing caused by the fact that a plurality of pulses are hit in a repetition period in a traditional device is solved, the detection interval time is shortened, the measurement speed is greatly improved, and the broadband large-vibration measurement capability of the system is improved.

The invention provides a method for controlling an engine EGR rate by a combined pulse spectrum, belonging to the vehicle gasoline engine control field, comprising a basic EGR rate pulse spectrum parameter and a dynamic EGR rate pulse spectrum parameter, wherein, the basic EGR rate pulse spectrum parameter is standardized by a jack horse or optimized and standardized by the jack horse and a road parameter, the dynamic EGR rate pulse spectrum parameter is generated by the self-standardization of the self-study on line of a control system and the self-optimization, and the adaptively control of the EGR rate of the gasoline engine is controlled by the control system according to a control strategy. The combined pulse spectrum control way synthesized by the self-adapting study method is adopted; therefore, the influence of the change in a controlled system and the unknown change on the engine is corrected, thereby improving the control accuracy of the open-loop control and increasing speed. The self-adapting study controls the strategy generating a dynamic pulse spectrum and advances the predictive control, thereby correcting the control lag generated by various time-lag effects and improving the timeliness of the control.