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The book is a collection of academician Yanzhong Zhang’s research papers published in English. It represents the development of aerospace systems engineering and information technology in China over the past 4 decades. Regarded as the crucial reference materials of related disciplines, it falls into three categories, namely, information technique, aeronautical engineering strategy issue of development, as well as PhD thesis.

### Fast DFT Algorithm with [N–1]/2 Multiplications

A fast algorithm is proposed for recursively computing the DFTs of prime length. Only (N-1)/2 real multiplications are required to compute all N frequency components in terms of permuting the input data.

Yanzhong Zhang

### Fast DFT Algorithm Using Subgroup Convolutions

A method is presented for converting a DFT of length $$\left( {P^{M} - 1} \right)$$ P M - 1 into several subgroup circular convolutions of length M or divisor M. This decomposition leads to efficient methods for computing the DFT.

Yanzhong Zhang

### Minimisation of Read-Muller Polynomials with Fixed Polarity

An efficient algorithm for minimisation of Reed–Muller polynomials with fixed polarities is presented. The common terms of multiple-output polynomials are considered by applying a number of logical operations on their coefficients. The minimisation of the polynomials over extension Galois fields GF(2M) is considered. The average number of field multiplications for mapping a set of coefficients is reduced to less than $$M \cdot 2^{M - 2}$$ M · 2 M - 2 .

Yanzhong Zhang

### A Direct Algorithm for Synthesis of Stable Feedback Shift Registers

The sufficient and necessary conditions for generating a stable sequence by means of a stable feedback shift register (FSR) is proved in this paper. A direct algorithm is presented for synthesis of stable FSRs with a minimum number of stages n.

Yanzhong Zhang

### Indirect Synthesis of Stable Binary Sequences

An indirect method is presented for the synthesis of stable binary sequences by means of maximum transient feedback shift registers (FSRs). An algorithm for the synthesis of maximum transient FSRs and output mapping is developed. The feedback functions of maximum transient FSRs are presented.

Yanzhong Zhang

### Galois Field Representation of Finite State Machines

A systematic study for representing a finite state machine as a polynomial over Galois Field is presented. A Discrete Fourier Transform method is developed for computing the coefficients of polynomials. The representation of the machines which inputs and outputs possess different word lengths is presented. The cyclic subgroup property of the polynomial coefficients is revealed. This property considerably reduces the amount of computation. The conversion between one and multiple variable machines is discussed. The Ring-Sum representation and Fast Reed-Muller Transformation are also discussed.

Yanzhong Zhang

### Optimum Coefficients for Recursively Computing DFTs

The recursive computation of prime length DFTs has very simple structure and needs only one coefficient. The signal-to-noise ratio for fixed-point implementation of this algorithm is discussed. The optimum coefficients with maximum S/N ratio are presened.

Yanzhong Zhang

### Linearization of Nonlinear Systems Over GF(2M)

A method for linearing any non-linear systems over GF(2M) is presented in terms of increasing its dimensions. The linearization matrix can be obtained from a similarity transform of connection matrix. The similarity transform matrix $$\underline{P}$$ P ̲ contains a DFT of length (2M–1) over GF(2M). The connection matrix $$\underline{C}$$ C ̲ can be obtained from the truth table of systems. A computer method is proposed for studying of a non-linear system. The method can be used to detect the amplitude and period of oscillations in the systems.

Yanzhong Zhang

### Fast Implementation of Recursive DFTs

A fast implementation of recursive DFTs is presented. It only needs (N-1)/2 real multiplications to compute all N frequency components. A factor $$R_{T}$$ R T is introduced. If the ratio $$T_{m}/T_{a}$$ T m / T a of multiplier’s and adder’s period is greater than $$R_{T}$$ R T , this scheme is faster than FFT. The error of systems is studied. A parallel scheme of adders is proposed. This scheme is much faster than the usual serial adder. A scheme for fast re-ordering the input data is proposed. This increases the reordering speed and saves the memory size.

Yanzhong Zhang

### Finite State Machine Realization of IIR Digital Filters

A method is proposed for representing an IIR digital filter as a Finite State Machine (FSM). This representation only has a maximum error of 1/2 bit from the final result of infinite accuracy arithmetic, and has not any increase in errors during the processing period. The realization avoids the effects of coefficient quantization and multiplication arithmetic errors caused by finite word length on the performance of DSP system. A graph theory method is presented for removing the oscillations from the system with a minimal increase in noise and without any increase in complexity of systems.

Yanzhong Zhang

### Minimisation of Exclusive-OR Logic Functions

An efficient computer algorithm for minimisation of exclusive-OR logic function is presented. The algorithm is $$n/(1+(n-1)2^{-m})$$ n / ( 1 + ( n - 1 ) 2 - m ) times faster than fast Reed-Muller transform algorithm for minimizing an exclusive-OR function with n input variables.

Yanzhong Zhang

### Optimization of Multiple-Output Exclusive-OR Logic Circuits

A method is presented for optimizing multiple-output exclusive-OR logic circuits. The effect of common gates on the optimization of logic circuits is studied. The concepts of common function, residue function and remainder term are introduced. A computer method for searching the optimum polarity is proposed. This method can be used to design the logic circuit which needs the minimum number of exclusive-OR gates.

Yanzhong Zhang

### A Novel Interleaver Design Method for Turbo Codes

We introduce the concept of optimal period interleaver and present an interleaver design method based on optimal period interleavers. Simulation results are presented for turbo codes of memory length 3 using our interleavers. An order of magnitude improvement in bit error rate performance is obtained at high signal-to-noise ratio compared to turbo codes using other conventional interleavers.

Yanzhong Zhang

We propose to use turbo codes in a code-aided equalizer [1, 2] for mobile radio communications. The turbo codes used take advantage of good short interleavers designed by an algorithm we developed earlier [3–6]. Bit error rate performance in a multipath environment for frame size equal to 210 bits will be presented.

Yanzhong Zhang

### Performance Analysis of a Digital Acquisition Circuit for DS/FH Spread Spectrum Signals

Fast acquisition is the major challenge for DS (direct sequence)/FH (frequency hopping) spread spectrum system. A DS/FH acquisition circuit which implements a digital noncoherent correlation scheme is studied extensively. The closed-form expressions of the mean acquisition time by single dwell decision and two-dwell decision are obtained with the state diagram respectively. The results show that, in the circumstance of low signal noise ration (SNR), the approach of two-dwell decision performs better than the approach of single dwell decision.

Yanzhong Zhang

### Fine Timing and Frequency Synchronization for CMMB System

A fine timing and frequency synchronization algorithm is presented for an orthogonal frequency division multiplexing (OFDM) system used in China mobile multimedia broadcasting (CMMB). The presented algorithm could accomplish the timing and frequency offset estimation using the perfect relation of training symbols. The simulation and practice results show the new algorithm could give out fine timing synchronization and accurate frequency offset estimation over AWGN channel and multipath channel.

Yanzhong Zhang

### Study and Implementation of Receiver Based on High Data Rate M-ary Spread Spectrum with Non-coherent Demodulation

Taking into account the request of high data rate and high spread spectrum processing gain, scheme of M-ary spread spectrum, fast PN-code acquisition and non-coherent demodulation is proposed. Experimental results show that with these methods, the system could reach 1 M data rate and 15 dB spread spectrum processing gain under $$10^{-6}$$ 10 - 6 bit error rate.

Yanzhong Zhang

### On Channel Estimation in DTMB Standard Using Time Domain PN Sequences

In some OFDM systems, time domain CP (cyclic prefix) and scattered pilots are used for synchronization and channel estimation. While in novel OFDM broadcasting systems, such as China Digital Terrestrial Multimedia Broadcasting Standard (DTMB), PN sequences rather than cyclic prefixes are inserted as guard interval between N-point IFFT blocks, which are also used as training symbols. This paper proposed a frequency domain transform method for channel estimation in time domain PN based OFDM systems. With simulation results, comparing to LS-DFT method that using scattered pilots for channel estimation, it is shown that our proposed method can provide satisfactory performance in time domain PN based terrestrial television broadcasting standard.

Yanzhong Zhang

### On Dual Timing Modulator for Chinese Digital Terrestrial Multimedia Broadcasting

A novel design of modulator for Chinese Digital Terrestrail Multimedia Broadcasting Standard id presented. Different from the traditional system of digital TV modulator, a simplified GPS/Compass2 dual timing receiver is embedded into the Single Frequency Network (SFN) block, which is removable and independent from the modulator. With this modification, the timing availability and the feasibility of switching between Multi-Frequency Network (MFN) and SFN mode is increased and meanwhile the costs are reduced. The lab tests are based on the prototype of this modulator, which is assembled with existing mature chips and modules, the results show the performance meets the Chinese National Standard on modulators and SFN applications.

Yanzhong Zhang

### Optimized Soft-Decision De-Mapping for Chines Terrestrail DTV Standard

An optimized soft-decision de-mapping method for Chinese Terrestrial DTV (Digital TV) Broadcasting Standard is proposed, which can be used on 64QAM, 32QAM, 16QAM and 4QAM de-mapping that compliant with the standard. Using the simplified de-mapping algorithm, the hardware resource usage and working speed are both optimized. Especially for 32QAM mode, comparing to traditional method, 75% hardware resource is saved, and the maximum working speed is 11% faster. The method is already implemented in the Chinese Terrestrial DTV receiver.

Yanzhong Zhang

### Design and Implementation of Single-Carrier MIMO Transmission with Frequency Domain Equalization

A multiple-output (MIMO) single-carrier frequency domain equalization (SC-FDE) testbed which can emulate a practical broadband system is described. A scheme combining space–time transmit diversity with SC-FDE was implemented and evaluated on the testbed. After the hardware configuration, software algorithms incorporating the space–time block coding and decoding, synchronization, channel estimation and frequency domain equalization are explained, followed by some field measurements which validating our design and implementation. It is showed that this software reconfigurable testbed is flexible and convenient to evaluate different system performance in kinds of wireless environments.

Yanzhong Zhang

### Novel Fast Acquisition Algorithm for DS/FH System

Based on differential correlation technique, novel fast acquisition algorithm is developed for hybrid direct sequence and frequency hopping (DS/FH) system. Specifically, by using differential correlation for PN code phase and parallel searching for frequency, the fast acquisition is realized. Furthermore, in terms of acquisition time and hardware resources consumption, the proposed differential correlation acquisition method is compared with the conventional waiting self synchronization acquisition method and frequency parallel searching acquisition method. Analytical and simulation results reveal that the proposed algorithm can be used in DS/FH system.

Weining Song, Yanzhong Zhang, Dingrong Shao, Shujian Li, Xiaojie Wen

### A Frame-Related Approach for Performance Improvement of MPE-FEC in DVB-H

Digital Video Broadcasting-Handheld (DVB-H) is a new digital terrestrial broadcasting standard customized for the multimedia service on the mobile devices and the handheld terminals. It introduces a technique known as multi-protocol encapsulation forward error correction (MPE-FEC) for the IP-datagrams in the data link layer to improve the mobile performance. Every MPE-FEC frame is constructed independently in the DVB-H standard. In this paper, a frame-related coding approach for MPE-FEC frame is proposed. When a MPE-FEC frame is built during the data link layer encoding process, the rightmost n columns in the MPE part of the current MPE-FEC frame are filled with the data populated from the leftmost n columns of its previous MPE-FEC frame. After the encoding process, a correlation is set up between the adjacent frames. This correlation can be utilized by the proposed decoding algorithm to enhance the error correction capability. The theoretical analysis and simulations results show that the proposed approach can provide better error correction capability than the DVB-H standard as well as the conventional zero-padding method in random noise channels. As a more efficient decoding strategy, the proposed approach is a good candidate for the decoding of MPE-FEC frame.

Rongke Liu, Yan Wang, Yanzhong Zhang

### Modified Block-Matching 3-D Filter in Laplacian Pyramid Domain for Speckle Reduction

The Laplacian pyramid-based block-matching 3-D filtering (BM3D) is proposed (LPBM3D) for despeckling the speckle image. For BM3D in each pyramid layer, the criterion used to collect blocks in the 3-D groups to the actual data statistics is devised. An adaptive wavelet thresholding operator that depends on both noise level and signal characteristics is proposed. The performance of the proposed LPBM3D method has been compared with the state-of-the-art methods, including the recently proposed nonlocal mean (NLM) and BM3D method. Experimental results show that the visual quality and evaluation indexes outperform the other methods with no edge preservation. The proposed algorithm effectively realizes both despeckling and edge preservation.

Donghai Wen, Yuesong Jiang, Yanzhong Zhang, Yuntao He, Houqiang Hua, Rong Yu, Xiaofang WU, Qian Gao

### Aviation Environmental Technology and Science

With the development of aviation undertaking, the effect caused by aircraft to the environment is increasingly growing. As aircraft are flying at high altitude, the pollution discharged as a result has more obvious effect on the environment than that discharged on the ground, and more easily leads to greenhouse effect and change of the global climate.

Zhang Yanzhong

### The Future Aircraft and Its Challenges on Aeronautical Technology

The future special aircraft are presented. Different helicopters, mini-UAVs, ground effect, airships and tilt-rotors developing in China are described. The challenges of future aircraft on aeronautical technology are described. Supersonic flight, advanced aerodynamics, new aero-engines, smart structures, new materials, fly by light, free flight, new fuels, virtual reality technologies required by the 21st century aircraft are presented.

Zhang Yanzhong

### Shock Response Spectrum Analysis with a Computer and a Fourier Analyser

In this paper the exact definition of shock response spectrum is given. The relation between Fourier spectrum of shock pulse and residual shock response spectrum is discussed with the following relationship: $$S\left(f \right)\, = \,2\pi f \, F(f)$$ S f = 2 π f F ( f ) . Finally, with paper introduces the programming of real-time analysing shock response spectrum with a mini-computer and a Fourier Analyser. Shock may be defined as suddenly transmission of a large amount of kinetic energy to a mechanical system which takes place in a relatively short time compared with the natural period of the mechanical system. It can produce very large force and acceleration and cause severe mechanical damage. In order to study the mechanical damage effect of shock and find an effective method of shock control, it is necessary to introduce the concept of shock response spectrum.

Zhang Yan Zhong

### Optimum Removal of LCOs in Digital Systems

A Finite State Machine method is proposed for realizing IIR digital filters. This realization has a maximum error of 1/2 bit from the final result of infinite precision arithmetic, and has no growth of errors during the processing period. It avoids the effects of the filter coefficient quantization and multiplication arithmetic errors. A connection matrix method is presented for detecting and locating the limit cycle oscillations in digital filters. The concept of Sub-Optimum Successor is introduced based on the defined error function. A Graph Theory method is proposed for removing Limit Cycle Oscillations from digital filters. This method breaks the filter's cycles, connects the unstable state to its sub-optimum successor, and forms a tree graph of stable filters. It introduces a minimum increase in noise and hardly any increase in complexity of hardware.

Y. Z. Zhang, T. W. Cole, Y. F. Yao

### Composite Attitude Control for Flexible Spacecraft with Simultaneous Disturbance Attention and Rejection Performance

In this paper, a composite attitude control approach for orbiting spacecraft with rigid central hubs and flexible appendages is presented. The established attitude control model consists of the vibration modes excited by the rigid body, the space environment disturbances, the measurement noises, and the model uncertainty. The model is formulated into a dynamic system with two types of disturbance inputs. A composite control law with the simultaneous disturbance attenuation and rejection performance is presented for the flexible spacecraft system subject to multiple disturbances. The disturbance-observer-based control is designed for feedforward compensation of the elastic vibration. The $${H_\infty }$$ H ∞ state-feedback controller is designed to perform the robust attitude control in the presence of the space environment disturbances, measurement noises, and the model uncertainty. Numerical simulations show that the performance of the attitude control systems can be improved by combining the disturbance observer with $${H_\infty }$$ H ∞ state-feedback control.

H. Liu, L. Guo, Y. Zhang

### Geometry and Accuracy of Specular Points in GPS-Reflection Altimetry

The sea surface height recovery methods and error analysis of altimetry using GPS reflected signal are explored in this paper. For the case when the receiver is at low altitude positions, the analytical equation of the sea surface height error is obtained; and for the case when the receiver is at high altitude positions, a novel method which has a concise mathematical formulation and efficient solution is proposed. Moreover, the proposed method can obtain more accurate solution than methods currently available in the literature. Analysis and simulation show that the sea surface height error and all the measurement errors are of the same order of magnitude when the elevation angle is high.

Guo Jia, Yang Dongkai, Ling Keck Voon, Shao Dingrong, Zhang Yanzhong

### Accuracy Assessment of Single and Double Difference Models for the Single Epoch GPS Compass

The single epoch GPS compass is an important field of study, since it is a valuable technique for the orientation estimation of vehicles and it can guarantee a total independence from carrier phase slips in practical applications. To achieve highly accurate angular estimates, the unknown integer ambiguities of the carrier phase observables need to be resolved. Past researches focus on the ambiguity resolution for single epoch; however, accuracy is another significant problem for many challenging applications. In this contribution, the accuracy is evaluated for the non-common clock scheme of the receivers and the common clock scheme of the receivers, respectively, we focus on three scenarios for either scheme: single difference model vs. double difference model, single frequency model vs. multiple frequency model and optimal linear combinations vs. traditional triple-frequency least square. We deduce the short baseline precision for a number of different available model and analyse the difference in accuracy for these models. Compared with the single or double difference model of the non-common clock scheme, the single difference model of the common clock scheme can greatly reduce the vertical component error of baseline vector, which results in higher elevation accuracy. The least squares estimators can also reduce the error of fixed baseline vector with the aid of the multi-frequency observation, thereby improving the attitude accuracy. In essence, the “accuracy improvement” is attributed to the difference in accuracy for different models, not a real improvement for any specific model. If all noise levels of GPS triple frequency carrier phase are assumed the same in unit of cycles, it can be proved that the optimal linear combination approach is equivalent to the traditional triple-frequency least squares, no matter which scheme is utilized. Both simulations and actual experiment have been performed to verify the correctness of theoretical analysis.

Wantong Chen, Honglei Qin, Yanzhong Zhang, Tian Jin

### Assessment of GNSS Orthogonal Transformation Model

GNSS relative positioning technique is an important field of study, in which the standard ‘GNSS Baseline Model’ is often used. Differencing between observation equations is used to construct the mathematical model, since this method can eliminate some common errors in the GNSS signal measurements. The ‘Orthogonal Transformation’ method can also construct the GNSS Baseline Model. However, as is described by some scholars, this model may avoid some drawbacks of Double Differencing (DD) while maintaining all the advantages. For comparison purposes, this model is evaluated and theoretical equivalence of both approaches is proved for the short baseline from two aspects; the Integer Ambiguity Resolution and the conditional least-squares baseline vector.

Wantong Chen, Yanzhong Zhang

### The Development of Large Aircraft C919 and C929

In the present article, the history of the development of large aircraft (LA) is summarized and the reasons for developing homemade large aircraft (HLA) in China are also analysed. Strategic targets of the Chinese large aircraft are proposed. The development situations of the airplane C919 and development strategies are also introduced in present paper. In addition, key technologies aircraft are proposed for large wide-bodied.

Zhang Yanzhong

### Integration of GPS and Dead Reckoning Navitation System Using Moving Horizon Estimation

In this paper, we propose an integration of GPS and dead reckoning navigation system based on moving horizon estimation (MHE) in order to improve its performance. The basic idea of MHE is to minimize an estimation cost function defined on a sliding window composed of a finite number of time stages. From stimulation results we have done an objective comparison which leads us to confirm that MHE method is more accuracy than Unscented Kalman Filter (UKF) and Extended Kalman filter (EKF).

Halima Mansour Omar, Zhang Yanzhong, Zhang Bo, Haris Ubaid Gul

### Globalization of R&D: New Trend of Economy Globalization

The rapid development of economy globalization has exerted significant influence on the progress of the world.

Zhang Yanzhong

### Building a Conservation-Minded Society by Means of Science and Technology Innovation

To build a conserving-minded society is one of the basic policies of China, an important practice in the construction of socialism with Chinese characteristics and also an obligatory duty for the engineering and technology fields.

Zhang Yanzhong

### Digital Signal Processing Systems with Finite State Machine Realization

The research contained in this dissertation is a result of my own work at the Cambridge University Engineering Department. The work is original except where reference is made to the work of others, and includes nothing which is the outcome of work done in collaboration: It has not been submitted, in part or whole, to any other university for any degree.

Yanzhong Zhang