Formal models of communicating and concurrent systems are one of the most important topics in formal methods, and process calculus is one of the most successful formal models of communicating and concurrent systems. In the previous works, the author systematically studied topology in process calculus, probabilistic process calculus and pi-calculus with noisy channels in order to describe approximate behaviors of communicating and concurrent systems as well as randomness and noise in them. This article is a brief survey of these works.

The development of the theory on quantum systems control in the last 20 years is reviewed in detail. The research on the controllability of quantum systems is first introduced, then the study on the quantum open-loop control methods often used for controlling simple quantum systems is analyzed briefly. The learning control method and the feedback control method are mainly discussed for they are two important methods in quantum systems control and their advantages and disadvantages are presented. According to the trends in quantum systems control development, the paper predicts the future trends of its development and applications. A complete design procedure necessary for the quantum control system is presented. Finally, several vital problems hindering the advancement of quantum control are pointed out.

Many studies, both experimental and numerical, were devoted to the electric current of corona discharge and some mathematical models were proposed to express it. As it depends on several parameters, it is difficult to find a theoretical or an experimental formula, which considers all the factors. So we opted for the methodology of experimental designs, also called Tagushi s methodology, which represents a powerful tool generally employed when the process has many factors to consider. The objective of this paper is to model current using this experimental methodology. The factors considered were geometrical factors (interelectrode interval, surface of the grounded plane electrode, curvature radius of the point electrode), climatic factors (temperature and relative humidity), and applied high voltage. Results of experiments made it possible to obtain mathematical models and to analyse the interactions between all factors.

This paper introduces a new protocol routing medium access control (RMAC) that integrates the routing and medium access control (MAC) layer protocol. They can both reduce latency and save energy in the wireless sensor network (WSN) while most others propose protocols that sacrifice latency for energy. To make RMAC fit WSN better, we designed an easy and efficient routing protocol base station flooding (BSF) and then integrated it with a MAC protocol timing out MAC (TMAC) [1], while traditionally BSF and TMAC work separately at two layers. We call this two-layer protocol (TLP). We theoretically proved the advantages of RMAC over TLP and evaluated RMAC over NS-2. The simulation results show that RMAC spends half the latency of TLP, as well as consumes less energy than TLP.

Orthogonal frequency division multiplexing (OFDM) can fully use the frequency band and transmit data at high speeds. The ADSP-TS101 is a high performance digital signal processor (DSP) with good properties that include parallel processing and a high speed. Aimed at the real-time processing requirement of the OFDM algorithm, an underwater acoustic communication system with real-time processing capability is carried out. The system is mainly composed of multiple ADSP-TS101s, a multi-channel synchronous sample module and a field programmable gate array (FPGA) chip. The multiprocessor structure is made up of a cluster/data flow associated multiprocessing parallel processing structure as the operation kernel, and a multi-channel synchronous sample module is designed to realize no phase warp among the multiple channels  data at the same time. The digital modulation/demodulation methods are applied to the OFDM algorithm. Through experiments in a lake, the results show that the system has good stability and real-time processing capability, thus satisfying the design requirements.

Emotion plays an essential role in the adaptation and social communication of organisms. Similarly, an appropriately timed and clearly expressed emotion is a central requirement for believable interactive virtual humans. Presently, incorporating emotion into virtual humans has gained increasing attention in the academia and industry. This strong interest is driven by a wide spectrum of promising applications in many areas such as virtual reality, e-learning, entertainment, etc. This paper introduces an emotion model of artificial psychology, in which the transition of emotion can be viewed as a Markov process and the relation of emotion, external incentive and personality can be described by a Markov decision process (MDP). In order to demonstrate the approach, this paper integrates the emotion model into a system composed of voice recognition and a realistic facial model. Thus, the model could be used for generating a variety of emotional expressions of autonomous, interactive virtual human beings.

In wireless sensor networks, data fusion (in-network processing) is a critical issue because sensor networks are energy-constrained and bandwidth-constrained. Recently, a new scheme based on mobile agent has been proposed to solve the problem. The order and number of nodes on the route traversed by a mobile agent determine the energy consumption, and hence, they have a significant impact on the overall performance of the whole system. Considering the limited transmission range of sensor nodes, we showed that this routing problem in a multi-hop cluster could be modeled as a node-weighted traveling tourist problem (TTP). We proved that the problem was nondeterministic polynomial time (NP)-complete. Then we presented a new approximation algorithm to solve the problem. Simulation experiments demonstrate that the proposed heuristic is more energy-efficient than the two earlier ones.

In order to improve the precision of the target detection in wireless sensor networks, a new approach based on genetic algorithm (GA) was proposed to optimize the placement of the sensor. The target location problem was transformed into locating a target at a grid point through modeling the sensor field as a grid of points. Moreover, the sensor placement problem was formulated as a combinatorial optimization problem, which is aimed at minimizing the maximum discrimination error under the restraints of limited cost and complete coverage. The GA approach uses binary coding to represent the location, and both single parent crossover operator and single parent mutation operator are used to improve its speed and efficiency. Experimental results have shown that a global optimal solution can be quickly obtained using the proposed method and the precision requirement for target location is satisfied.

The development of document image databases is becoming a challenge for document image retrieval techniques. Traditional layout-reconstructed-based methods rely on high quality document images as well as an optical character recognition (OCR) precision, and can only deal with several widely used languages. The complexity of document layouts greatly hinders layout analysis-based approaches. This paper describes a multi-density feature based algorithm for binary document images, which is independent of OCR or layout analyses. The text area was extracted after preprocessing such as skew correction and marginal noise removal. Then the aspect ratio and multi-density features were extracted from the text area to select the best candidates from the document image database. Experimental results show that this approach is simple with loss rates less than 3% and can efficiently analyze images with different resolutions and different input systems. The system is also robust to noise due to its notes and complex layouts, etc.

As a new technology, mobile agent (MA) shows a wide application in the field of network technology. However, security has been one of the crucial problems in its application. A new protection model based on a trusted element is presented in this paper. The trusted element, which differs from the traditional trusted hardware such as a smart card or a co-processor, offers a third party service based on an encrypted circuit construction. The procedure of constructing an encrypted circuit is introduced and the method of using the trusted service to protect the MA is also described. An application example is given to show how to use the new model at the end of the paper.

The key challenge of dynamic peer communication is how to realize secure and efficient group key management. A two rounds key agreement protocol for dynamic peer group (DPG) is proposed in this paper. The protocol, which was obtained by combining the ElGamal encryption scheme with the ElGamal signature scheme, is efficient and simple. The protocol is proven secure against passive attack by using indistinguishable method. Moreover, both perfect forward secrecy (PFS) and key independence (KI) were achieved. Because the protocol is based on the broadcast channel, it is also suitable for key agreement in wireless communications, especially in ad-hoc networks.

A nonlinear proportion integration differentiation (PID) controller is proposed on the basis of recurrent neural networks, due to the difficulty of tuning the parameters of conventional PID controller. In the control process of nonlinear multivariable system, a decoupling controller was constructed, which took advantage of multi-nonlinear PID controllers in parallel. With the idea of predictive control, two multivariable predictive control strategies were established. One strategy involved the use of the general minimum variance control function on the basis of recursive multi-step predictive method. The other involved the adoption of multi-step predictive cost energy to train the weights of the decoupling controller. Simulation studies have shown the efficiency of these strategies.

A novel bandwidth allocation strategy along with a connection admission control technique was proposed to improve the utilization of network resources. It provides the network with better quality-of-service (QoS) guarantees, such as new call blocking probability (CBP) and handoff call dropping probability (CDP) in multimedia low earth orbit (LEO) satellite networks. Simulation results show that, compared with other bandwidth allocation schemes, the proposed scheme offers very low call dropping probability for real-time connections while, at the same time, keeping resource utilization high. Finally we discussed the fairness for the borrowed nonreal-time connections under three different channel borrowing methods.

The production mechanism of non-return-to-zero (NRZ), return-to-zero (RZ) and carrier suppressed return-to-zero (CSRZ) was analyzed theoretically in this paper. We compared the transmission performance of CSRZ with RZ and NRZ formats at 10 Gb/s system by numerical simulation. And we simulated the transmission model constructed with Erbium-doped fiber amplifier (EDFA) as the solo amplifier and the chirped fiber Bragg grating (CFBG) as the solo dispersion compensator used in the system. A practical 8×10 Gb/s 2 560 km transmitted experiment was conducted in straight line with these different modulation formats mentioned above and the experiment results show very good agreement with the result of computer simulation. The CSRZ format is more effective than other formats in the system, and involved only 2.5 dB power penalty cost in the practical 2 560 km error-free experiment. The results also show that CSRZ will help to optimize the transmitted results and reduce the transmitted penalty further.

In order to periodically reassess the status of the alternate path route (APR) set and to improve the efficiency of alternate path construction existing in most current alternate path routing protocols, we present a cross-layer design and ant-colony optimization based load-balancing routing protocol for ad-hoc networks (CALRA) in this paper. In CALRA, the APR set maintained in nodes is aged and reassessed by the inherent mechanism of pheromone evaporation of ant-colony optimization algorithm, and load balance of network is achieved by ant-colony optimization combining with cross-layer synthetic optimization. The efficiency of APR set construction is improved by bidirectional and hop-by-hop routing update during routing discovery and routing maintenance process. Moreover, ants in CALRA deposit simulated pheromones as a function of multiple parameters corresponding to the information collected by each layer of each node visited, such as the distance from their source node, the congestion degree of the visited nodes, the current pheromones the nodes possess, the velocity of the nodes, and so on, and provide the information to the visiting nodes to update their pheromone tables by endowing the different parameters corresponding to different information and different weight values, which provides a new method to improve the congestion problem, the shortcut problem, the convergence rate and the heavy overheads commonly existed in existing ant-based routing protocols for ad-hoc networks. The performance of the algorithm is measured by the packet delivery rate, good-put ratio (routing overhead), and end-to-end delay. Simulation results show that CALRA performs well in decreasing the route overheads, balancing traffic load, as well as increasing the packet delivery rate, etc.

To improve stability and performance of the signal source and sweeping detection, as well as to extract abundant and reliable signal, the direct digital synthesis technology was employed to design the generator of the source which formed sweeping frequencies of sine wave output from 1 to 20 MHz. The planar spiral coil was connected as an amplitude modulation circuit. The same coil adopted differential architecture for signal detection and extraction. The MC1595 was utilized to compose a phase detector in which difference of phases varies with the change of frequencies. A low pass filter was designed to filter the carry waves of the sweeping source. Thereby the system gained abundant data and its stability was improved. Further, the spatial resolution of the system was enhanced. All of the above favors the use of software in the magnetic focused conductivity tomography system (MFCT) to reconstruct the image of conductivity within the human body.

The article introduces an advanced approach of fiber grating strain demodulation based on the principle of polarized-light interference. This method can solve the problem of cross sensitivity in fiber Bragg grating sensor. As for the yttrium vanadate (YVO₄) crystal polarized-light interferometer, if there are two different fiber Bragg gratings that have a ? rad phase difference, one is used for strain sensor and the other is used for temperature compensating. Then the problem of cross sensitivity can be overcome. The analyses of the strain demodulation resolution show that with a decrease in crystal thickness the resolution increases. The experiment shows that when the thickness of YVO₄ crystal is 0.5 mm, the effect of cross-sensitivity will be reduced to 0.13 µε/?C, which is 1.6% of the effect used by only one fiber Bragg grating for strain measure. And when the thickness is 0.1 mm the cross-sensitivity will be reduced to 0.006 7 µε/?C, which is less than 0.08%. Less thickness of crystal is beneficial for the resolution of strain measure, but the machining of small thickness crystal is difficult. To solve this problem, a new scheme of polarized-light interferometer with the structure of double layer crystal was analyzed.

To improve the transient stability of multimachine power systems, observational linearization and tracking objective excitation control laws were derived from the phasor measurement unit (PMU), observational linearization, and tracking objective control theory based on synchronized coordinates and reference generator coordinates. The control strategies utilized real-time state variables obtained by PMU to linearize the state equations of the system, and then the linear optimal control strategy was used to design excitation controllers. The inaccuracy of the local linearization method and the complexity of the system models designed in the exact linearization method for nonlinear systems were avoided. Therefore, the control strategies were applied in real time. Simulation results show that the proposed method can improve the transient stability of power systems more efficiently than nonlinear optimal excitation control.

A quantitative index martensite fraction was used to describe the phase transformation degree of shape memory alloy (SMA). On the basis of the martensite fraction, a non-linear analysis model for major and minor hysteresis loops was developed. The model adopted two exponential equations to calculate the martensite fractions for cooling and heating, respectively. The martensite fractions were derived as the relative parameters were adjusted timely according to continuous, common initial and common limit constraints. By use of the linear relationship between the curvature of embedded SMA actuator and SMA s martensite fraction, the curvature was determined. The results of the simulations and experiments prove the validity and veracity of the model.

A backscatter model was developed for measuring wind field with the far-field approximation method. The theoretical computation and computer simulations with one spatial dimension show that this model can realistically describe the physical meaning and process of the three methods in wind measurements including the spaced antenna (SA) method, Doppler beam swing (DBS) method, and spaced interferometry (SI). The computational difficulties of the traditional theoretical model cannot only be smoothed away, but common characteristics and differences of the three methods can be compared deeply. The comparison of the numerical results between the Wuhan medium frequency (MF) radar (30º N, 114ºE) observation and the computer simulation of the full correlation analysis (FCA) of the SA method indicates that the two results agree very well and this model has practical application.