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43 results about "Composite Sequence" patented technology

A collection of Reporter or CompositeSequence Design Elements, annotated through the association to BioSequence. (caMAGE)

Remote underwater acoustic communication method based on soft-demodulation soft-decoding joint iteration

The invention provides a remote underwater acoustic communication method based on soft-demodulation soft-decoding joint iteration. The method comprises the following steps that: a transmitting end performs low density parity check (LDPC) coding on a binary information sequence which is sent by a signal source, performs quaternary phase shift keying (QPSK) modulation and Gray mapping, maps code elements to one of four positions in a constellation diagram by taking two code elements as a group, performs Walsh-m composite sequence spectrum spreading to obtain a signal to be transmitted, and converts a digital signal to be transmitted into an underwater acoustic signal; and an underwater acoustic transducer at a receiving end converts the received underwater acoustic signal, de-spreads by using a composite sequence which is the same as that of the transmitting end to obtain a receiving signal, performs self-adaptation decision feedback equalization to obtain an amplitude fading complex signal, performs soft-demodulation soft-decoding joint iteration on the signal, stops joint iteration after set iteration frequency is reached, performs belief propagation (BP) decoding on an LDPC decoder and outputs a bit value to a sink. By the method provided by the invention, the reliability of remote underwater acoustic communication is improved. The method is applicable to the remote underwater acoustic communication.
Owner:三亚哈尔滨工程大学南海创新发展基地

Fast and accurate synchronization method for spread spectrum underwater acoustic communication

The invention relates to the field of underwater acoustic communication, particularly to a fast and accurate synchronization method for spread spectrum underwater acoustic communication. The method adopts an m sequence cyclically extended as a frame header, a receiving end uses an m-sequence thumbtack-shaped time-frequency blur characteristic and adopts the fast Walsh transform processing to successively perform frequency deviation coarse and fine search and estimate the initial frequency deviation value of a frame header signal, and a sliding correlation method is used to estimate the starting moment of the frame header signal, so as to complete frame synchronization. A time and frequency synchronization tracking loop is designed by adopting fast Walsh transform processing to further complete time and frequency tracking on each spread spectrum symbol in a frame body. The method has the advantages of overcoming the defect that the conventional method needs to store a plurality of PN sequence versions of different frequency offset, thereby occupying a small amount of storage, and using the FWT processing to reduce the amount of calculation to a large extent, and the composite sequence generated by the m sequence as a spread spectrum sequence; therefore, the method is suitable for spread spectrum underwater acoustic communication of M-ary and PPM hybrid modulation, and has good real-time performance and practicality.
Owner:THE 715TH RES INST OF CHINA SHIPBUILDING IND CORP

Demodulation with separate branches for phase and amplitude

A receiver architecture is disclosed for use in Time-Division Multiple Access (TDMA) and related digital radio applications which combines the principal benefits of the conventional hard-limiting and linear receiver architectures to support switched-antenna diversity and multipath equalisation without the need for receiver gain control. A further feature of the receiver architecture is that minimises the dynamic range needed by the digital signal processing stages thereby reducing complexity, power consumption and cost compared to known arrangements. The (TDMA) radio frequency signal is separated into two components by the analogue section of the receiver: one component characterising the signal's phase, either absolute or differential, the second component characterising the signal's instantaneous magnitude. The (constant-envelope) phase component is digitised by an analogue-to-digital converter (ADC) to form a sequence of phase samples. In a parallel path, the magnitude component is digitised by a second, synchronised ADC, digitally processed to obtain a sequence of coefficients characterising the normalised envelope variations and this is then combined with corresponding (in time) samples of the phase sequence to form a single, composite sequence characterising both the phase and amplitude variations of the received radio frequency signal. This composite sequence is then processed by a digital demodulator / equaliser to recover the transmitted data.
Owner:CADENCE DESIGN SYST INC

Calculation method suitable for transfer rate matrix of composite state spatial model

The invention discloses a calculation method suitable for a transfer rate matrix of a composite state spatial model. The calculation method comprises the following steps: 1: dividing a research object into subsystems, and determining a composite sequence; 2: establishing the state spatial model of each subsystem, and listing and writing the transfer rate matrix; 3: adopting a transfer frequency conservation principle to carry out state merging on the subsystems to obtain the transfer rate matrix after subsystem is simplified; 4: according to a composite sequence, successively combining, correcting and simplifying the subsystems to finally obtain the transfer rate matrix corresponding to the state spatial model of the research object; and 5: substituting the transfer rate matrix of the research object into a state space method calculation formula to obtain each steady-state probability of the research object. The calculation method can adopt the formula to directly list and write the transfer rate matrix corresponding to the combined state spatial model, so that the combination and simplification process of the state spatial model can be realized through programming software including Matlab and the like, and a state spatial algorithm is convenient and universal.
Owner:HEFEI UNIV OF TECH

Method for calculating cross-voltage fault current of mixed-voltage double-line single phase crossing single phase on same tower

The invention discloses a method for calculating cross-voltage fault current of mixed-voltage double-line single phase crossing single phase on same tower. The method comprises the following steps of respectively calculating positive and negative sequence impedances and positive and negative sequence networks of two power distribution systems with different voltage classes which are reduced to a fault port; measuring a double-line zero sequence constant network between the two power distribution systems with different voltage classes; according to the double-line zero sequence constant network, calculating and unifying an equivalent zero sequence network of the two power distribution systems with different voltage classes; according to the positive and negative sequence networks and the equivalent zero sequence network, combining into a composite sequence network diagram of the two power distribution systems with different voltage classes; according to the positive and negative sequence impedances, calculating the boundary condition of the cross-voltage grounding fault of single phase crossing single phase; according to the composite sequence network diagram and the boundary condition, calculating the fault current. The method has the advantages that by utilizing the double-port network theory, the calculating accuracy of the cross-voltage fault of the mixed-voltage double-line on same tower is guaranteed, the high-order matrix operation is avoided, and the calculation is simple and reliable.
Owner:NORTH CHINA ELECTRIC POWER UNIV (BAODING) +1

Single-phase earth fault rapid linear calculation method applied to unbalanced distribution network

ActiveCN110133420ASimple calculationImplementing low-dimensional linear solversElectrical testingPhase shiftedControl power
The invention discloses a single-phase earth fault rapid linear calculation method applied to an unbalanced distribution network. Based on the thought of a sequence component method, compensation is performed on asymmetric elements by the adoption of a controlled power source on the basis of using symmetrical component transformation, and meanwhile a phase shift process under different fault phases is simplified. Through the processing, a composite sequence network model suitable for single-phase earth fault calculation of the unbalanced distribution network can be obtained, and the model cancontinue to be simplified into a seven-node simplified linear calculation model. By use of the seven-node simplified calculation model, positive sequence voltages, negative sequence voltages and zerosequence voltages of substation buses and fault ports can be calculated, a positive sequence current, a negative sequence current and a zero sequence current of each feeder are calculated according tothe positive sequence voltages, the negative sequence voltages and the zero sequence voltages, and therefore single-phase earth fault calculation on the unbalanced distribution network is realized. Through the method, the calculation process of solving a single-phase earth fault of the unbalanced distribution network is greatly simplified, low-dimensional linear solving is realized, and calculation speed is increased.
Owner:SOUTH CHINA UNIV OF TECH

Method with phase selection function for protecting composite-sequence component voltages of power transmission line

The invention discloses a method with a phase selection function for protecting composite-sequence component voltages of a power transmission line. The method includes computing a real portion of a ratio of each fault-phase negative-sequence current to a zero-sequence current; dividing the real portion of the ratio of each fault-phase negative-sequence current to the zero-sequence current by an absolute value of the ratio to obtain a direction coefficient; computing a zero-sequence voltage at a protection setting range for the transmission line; computing an equivalent negative-sequence voltage at the protection setting range for the power transmission line; forming a composite-sequence component voltage protection criterion by the zero-sequence voltage at the protection setting range for the power transmission line, the equivalent negative-sequence voltage and the direction coefficients. The method has the advantages that relay protection for single-phase earth faults of the power transmission line is implemented owing to distribution characteristics of zero-sequence voltages and negative-sequence voltages along the power transmission line, influence of transition resistance on the performance of protection actions is eliminated in principle, and the performance of the actions is unaffected by load currents or fault positions.
Owner:STATE GRID CORP OF CHINA +3

Production technology for bamboo-wood composite building template

The invention provides a production technology for a bamboo-wood composite building template. The production technology for the bamboo-wood composite building template comprises the following steps that step 1, bamboo curtains, eucalyptus planks and poplar wood pieces are dried in a drying room; step 2, the dried eucalyptus planks are sawn into rectangular wood pieces, the wood pieces are closely attached, no overlapping and gap exist, and the wood pieces are pieced together to form the eucalyptus planks through bonding threads; step 3, glue coating treatment is conducted on the pieced eucalyptus planks; step 4, the composite sequence is a poplar wood face layer, the eucalyptus plank, the bamboo curtain, the eucalyptus plank, the bamboo curtain, the eucalyptus plank and the poplar wood face layer, and the fiber directions of the eucalyptus planks are perpendicular to the fiber directions of the poplar wood face layers; step 5, the composite template is sent into a hydraulic machine to press; step 6, film coated paper impregnated with resin glue is laid on the pressed poplar wood face, and compression molding is conducted through a thermocompressor; step 7, after hot compression, edging and edge sealing of the periphery are conducted on the template. The production technology for the bamboo-wood composite building template adopts moso bamboo as a main material, the resources are rich, the price is cheap, and the production cost is low; the surface of the building template is flat and smooth, resin consumption is small, and the anti-bending and compressive strength are high.
Owner:ZHEJIANG KEXIN BAMBOO & WOOD

Method for acquiring asymmetrical short-circuit current DC components of complex power system

The invention relates to a method for acquiring asymmetrical short-circuit current DC components of a complex power system, and the method comprises the following steps of 1) respectively constructingcomposite sequence networks including a positive sequence network, a negative sequence network and a zero sequence network for calculating asymmetrical short-circuit current periodic components of the complex power system according to a fault point and a fault port, and increasing the reactance in an original branch of each sequence network to k times to form a positive sequence k network, a negative sequence k network and a zero sequence k network; 2) respectively acquiring an input impedance Z2sigma.N of the negative sequence network, an input impedance Z0sigma.N of the zero sequence network, an input impedance Z2sigma.k of the negative sequence k network and an input impedance Z0sigma.k of the zero sequence k network at the fault port; 3) calculating additional impedances under different types of short circuits, introducing the additional impedances into the complex power system, and simplifying the composite sequence networks to obtain a network simplified model; and 4) respectively calculating corresponding initial values of the DC components and decay time constants thereof for each type of asymmetric short circuit. Compared with the prior art, the method provided by the invention has the advantages of being suitable for a complex network, simple and accurate calculation, and the like.
Owner:SHANGHAI UNIVERSITY OF ELECTRIC POWER

A kind of production technology of bamboo-wood composite building formwork

The invention provides a production technology for a bamboo-wood composite building template. The production technology for the bamboo-wood composite building template comprises the following steps that step 1, bamboo curtains, eucalyptus planks and poplar wood pieces are dried in a drying room; step 2, the dried eucalyptus planks are sawn into rectangular wood pieces, the wood pieces are closely attached, no overlapping and gap exist, and the wood pieces are pieced together to form the eucalyptus planks through bonding threads; step 3, glue coating treatment is conducted on the pieced eucalyptus planks; step 4, the composite sequence is a poplar wood face layer, the eucalyptus plank, the bamboo curtain, the eucalyptus plank, the bamboo curtain, the eucalyptus plank and the poplar wood face layer, and the fiber directions of the eucalyptus planks are perpendicular to the fiber directions of the poplar wood face layers; step 5, the composite template is sent into a hydraulic machine to press; step 6, film coated paper impregnated with resin glue is laid on the pressed poplar wood face, and compression molding is conducted through a thermocompressor; step 7, after hot compression, edging and edge sealing of the periphery are conducted on the template. The production technology for the bamboo-wood composite building template adopts moso bamboo as a main material, the resources are rich, the price is cheap, and the production cost is low; the surface of the building template is flat and smooth, resin consumption is small, and the anti-bending and compressive strength are high.
Owner:ZHEJIANG KEXIN BAMBOO & WOOD
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