摘要:
This invention discloses an improved laser induced breakdown spectroscopy (LIBS) apparatus and method for the detection of mineral and metal contamination in liquid samples. The mineral and metal contaminant is first collected by filtering the liquid sample with a membrane filter. The membrane filter with the mineral and metal contaminant is then measured by a LIBS apparatus. The LIBS apparatus is based on a high repetition rate pulsed laser. The laser produces a train of laser pulses at a high repetition rate in the kHz (or even higher) range. When the laser beam hits the surface of the membrane filter, it generates several thousands of micro-plasma emissions per second. Synchronized miniature CCD array optical spectrometer modules collect the LIBS signal from these micro-plasma emissions. By adjusting the integration time of the spectrometer to cover a plurality of periods of the laser pulse train, the spectrometer integrates the LIBS signal produced by this plurality of laser pulses. Hence the intensity of the obtained LIBS spectrum can be greatly improved to increase the signal-to-noise ratio (SNR) and lower the level of detection (LOD).
摘要:
This invention discloses a laser induced breakdown spectroscopy (LIBS) apparatus based on a high repetition rate pulsed laser. The laser produces a train of laser pulses at a high repetition rate in the kHz or even higher range. When the laser beam hits the sample, it generates several thousands of micro-plasma emissions per second. Synchronized miniature CCD array optical spectrometer modules collect the LIBS signal from these micro-plasma emissions. By adjusting the integration time of the spectrometer to cover a plurality of periods of the laser pulse train, the spectrometer integrates the LIBS signal produced by this plurality of laser pulses. Hence the intensity of the obtained LIBS spectrum can be greatly improved to increase the signal-to-noise ratio (SNR) and lower the limit of detection (LOD). In addition, the influence of pulse to pulse variation of the laser is minimized since the obtained LIBS spectrum is the spectrum of a plurality of micro-plasma emissions produced by a plurality of laser pulses. The high repetition rate laser also makes it possible to measure the LIBS signal at a short and a long integration time and mathematically combining the two spectra to obtain a LIBS spectrum with enhanced dynamic range.
摘要:
This invention discloses an improved laser induced breakdown spectroscopy (LIBS) apparatus and method for the detection of mineral and metal contamination in liquid samples. The mineral and metal contaminant is first collected by filtering the liquid sample with a membrane filter. The membrane filter with the mineral and metal contaminant is then measured by a LIBS apparatus. The LIBS apparatus is based on a high repetition rate pulsed laser. The laser produces a train of laser pulses at a high repetition rate in the kHz (or even higher) range. When the laser beam hits the surface of the membrane filter, it generates several thousands of micro-plasma emissions per second. Synchronized miniature CCD array optical spectrometer modules collect the LIBS signal from these micro-plasma emissions. By adjusting the integration time of the spectrometer to cover a plurality of periods of the laser pulse train, the spectrometer integrates the LIBS signal produced by this plurality of laser pulses. Hence the intensity of the obtained LIBS spectrum can be greatly improved to increase the signal-to-noise ratio (SNR) and lower the level of detection (LOD).
摘要:
An efficient general QC-LDPC code decoder includes a general-purpose processor for distributing the storage storage space of the data memory block, and establishing an index for data addressing; a data memory block for storing the information used during decoding; a hardware accelerator for conducting part or all of the information processing operations including parity check, check node updating and variable node updating. A corresponding QC-LDPC code decoding method includes initializing the variable node information and performing parity check on the check matrix row block by row block; updating the check node row block by row block and updating the variable node column block by column block if any check equation is not met.
摘要:
A system and method for generating and detecting identifier sequence of a bandwidth-limited transmitter are disclosed, comprising an identifier sequence generating portion and a detection portion. The identifier sequence generating portion comprises: generating a frequency-domain random sequence; generating a frequency-domain orthogonal sequence; performing frequency-domain truncation; performing frequency-time transformation; and performing cycle extension. The identifier sequence receiving portion comprises: truncating the time-domain for the received signal; performing time-frequency domain transformation to obtain a frequency-domain signal; generating frequency-domain random sequence; generating a frequency-domain orthogonal sequence; correlating the frequency-domain orthogonal sequence with the frequency-domain signal de-scrambled by the frequency-domain random sequence; and detecting an output from a frequency-domain correlator by a threshold detecting device and determining the transmitter identifier sequence. The random sequence bandwidth generated by the system and the method of the present invention can be configured flexibly according to transmission bandwidth requirement, and the sequence may be arbitrarily allocated at the power of each frequency point inside the bandwidth. The present invention may be widely applied to multimedia broadcasting, terrestrial radio broadcasting, cable broadcasting and the like.
摘要:
Provided are a crop height regulatory gene from Arabidopsis thaliana, expression regulatory sequences thereof and uses thereof. The crop regulatory gene can be used to regulate the plant height, volume, tiller, yield, flower organ size, or seed size of crops.
摘要:
The present invention discloses a multi-carrier digital multimedia broadcast system and the digital information transmission method thereof. After RS encoding and byte interleaving, LDPC encoding, bit interleaving and constellation mapping to an upper layer of data streams in turn, the obtained data symbol is multiplexed with scattered pilots and continual pilots which include the system information to form an OFDM frequency domain symbol and scrambled; an OFDM time domain symbol is generated by IFFT transforming, and after inserted with the frame head to build a time slot, it is connected to form a signal frame of the physical layer; the signal frame of the physical layer is transmitted after being low-pass filtered and orthogonal upconverted. The system and method thereof provide wireless broadcast with high quality such as audio, video and multimedia data and the like for mobile, fixed and portable receivers, and can use the satellite transmission and terrestrial transmission method for transmitting. The method utilizes the LDPC OFDM scheme, and the system applies the microwave and large scale integrated circuit technologies while fulfills the needs for low cast and high performance.
摘要:
A method for constructing LDPC (Low-Density Parity-Check) code in the mobile digital multimedia broadcast system is provided, wherein the Low-Density Parity-Check matrix of the LDPC code is iteratively constructed according to a code-table and expansion method, and the code-table is a part of the constructed Low-Density Parity-Check matrix. According to the constructing method of the present invention, the LDPC code having excellent performance of error correcting coding which is applicable to the mobile digital multimedia broadcast system.
摘要:
Substituted imidazoles and thiazoles having the formula are useful for inhibiting farnesyltransferase. Also disclosed are farnesyltransferase-inhibiting compositions and methods of inhibiting farnesyltransferase in a patient.