Showing papers in "Science in China Series F: Information Sciences in 2014"

A computational cognition model of perception, memory, and judgment

Abstract: The mechanism of human cognition and its computability provide an important theoretical foundation to intelligent computation of visual media. This paper focuses on the intelligent processing of massive data of visual media and its corresponding processes of perception, memory, and judgment in cognition. In particular, both the human cognitive mechanism and cognitive computability of visual media are investigated in this paper at the following three levels: neurophysiology, cognitive psychology, and computational modeling. A computational cognition model of Perception, Memory, and Judgment (PMJ model for short) is proposed, which consists of three stages and three pathways by integrating the cognitive mechanism and computability aspects in a unified framework. Finally, this paper illustrates the applications of the proposed PMJ model in five visual media research areas. As demonstrated by these applications, the PMJ model sheds some light on the intelligent processing of visual media, and it would be innovative for researchers to apply human cognitive mechanism to computer science.

Observer-based adaptive fuzzy backstepping control of uncertain nonlinear pure-feedback systems

Abstract: In this paper, a new fuzzy adaptive control approach is developed for a class of SISO uncertain pure-feedback nonlinear systems with immeasurable states. Fuzzy logic systems are utilized to approximate the unknown nonlinear functions; and the filtered signals are introduced to circumvent algebraic loop systems encountered in the implementation of the controller, and a fuzzy state adaptive observer is designed to estimate the immeasurable states. By combining the adaptive backstepping technique, an adaptive fuzzy output feedback control scheme is developed. It is proven that the proposed control approach can guarantee that all the signals of the resulting closed-loop system are semi-globally uniformly ultimately bounded (SGUUB), and the observer and tracking errors converge to a small neighborhood of the origin by appropriate choice of the design parameters. Simulation studies are included to illustrate the effectiveness of the proposed approach.

Analog memristive memory with applications in audio signal processing

Abstract: Since the development of the HP memristor, much attention has been paid to studies of memristive devices and applications, particularly memristor-based nonvolatile semiconductor memory. Owing to its unique properties, theoretically, one could restart a memristor-based computer immediately without the need for reloading the data. Further, current memories are mainly binary and can store only ones and zeros, whereas memristors have multilevel states, which means a single memristor unit can replace many binary transistors and realize higher-density memory. It is believed that memristors can also implement analog storage besides binary and multilevel information memory. In this paper, an implementation scheme for analog memristive memory is considered. A charge-controlled memristor model is derived and the corresponding SPICE model is constructed. Special write and read operations are demonstrated through numerical analysis and circuit simulations. In addition, an audio analog record/play system using a memristor crossbar array is designed. This system can provide great storage capacity (long recording time) and high audio quality with a simple small circuit structure. A series of computer simulations and analyses verify the effectiveness of the proposed scheme.

On controllability and stabilizability of probabilistic Boolean control networks

Abstract: The controllability of probabilistic Boolean control networks (PBCNs) is first considered. Using the input-state incidence matrices of all models, we propose a reachability matrix to characterize the joint reachability. Then we prove that the joint reachability and the controllability of PBCNs are equivalent, which leads to a necessary and sufficient condition of the controllability. Then, the result of controllability is used to investigate the stability of probabilistic Boolean networks (PBNs) and the stabilization of PBCNs. A necessary and sufficient condition for the stability of PBNs is obtained first. By introducing the control-fixed point of Boolean control networks (BCNs), the stability condition has finally been developed into a necessary and sufficient condition of the stabilization of PBCNs. Both necessary and sufficient conditions for controllability and stabilizability are based on reachability matrix, which are easily computable. Hence the two necessary and sufficient conditions are straightforward verifiable. Numerical examples are provided from case to case to demonstrate the corresponding theoretical results.

Requirements model driven adaption and evolution of Internetware

Abstract: Today’s software systems need to support complex business operations and processes. The development of the web-based software systems has been pushing up the limits of traditional software engineering methodologies and technologies as they are required to be used and updated almost real-time, so that users can interact and share the same applications over the internet as needed. These applications have to adapt quickly to the diversified and dynamic changing requirements in the physical, technological, economical and social environments. As a consequence, we are expecting a major paradigm shift in software engineering to reflect such changes in computing environment in order to better address the fundamental needs of organisations in this new era. Existing software technologies, such as model driven development, business process engineering, online (re-)configuration, composition and adaptation of managerial functionalities are being repurposed to reduce the time taken for software development by reusing software codes. The ability to dynamically combine contents from numerous web sites and local resources, and the ability to instantly publish services worldwide have opened up entirely new possibilities for software development. In retrospect to the ten years applied research on Internetware, we have witnessed such a paradigm shift, which brings about many changes to the developmental experience of conventional web applications. Several related technologies, such as cloud computing, service computing, cyber-physical systems and social computing, have converged to address this emerging issue with emphasis on different aspects. In this paper, we first outline the requirements that the Internetware software paradigm should meet to excel at web application adaptation; we then propose a requirement model driven method for adaptive and evolutionary applications; and we report our experiences and case studies of applying it to an enterprise information system. Our goal is to provide high-level guidelines to researchers and practitioners to meet the challenges of building adaptive industrial-strength applications with the spectrum of processes, techniques and facilities provided within the Internetware paradigm.

Guaranteed transient performance based control with input saturation for near space vehicles

Abstract: This paper describes the design of guaranteed transient performance based attitude control for the near space vehicle (NSV) with control input saturation using the backstepping method. To improve the robust controllability of the NSV, the parameter adaptive method is used to tackle the integrated effect of unknown time-varying disturbance and control input saturation. Based on the backstepping technique and parameter estimated outputs, a robust attitude control scheme is proposed for the NSV with input saturation. A novel robust attitude control scheme is then proposed based on a prescribed performance bound (PPB) which characterizes the convergence rate and maximum overshoot of the attitude tracking error. The closed-loop system stability under both the developed robust attitude control schemes is proved using Lyapunovs method and uniformly asymptotical convergence of all closed-loop signals is guaranteed. Finally, simulation results are given to show the effectiveness of both the proposed robust constrained attitude control schemes.

Software-as-a-service (SaaS): perspectives and challenges

Abstract: Software-as-a-service (SaaS) has received significant attention recently as one of three principal components of cloud computing, and it often deals with applications that run on top of a platform-as-a-service (PaaS) that in turn runs on top of infrastructure-as-a-service (IaaS). This paper provides an overview of SaaS including its architecture and major technical issues such as customization, multi-tenancy architecture, redundancy and recovery mechanisms, and scalability. Specifically, a SaaS system can have architecture relating to a database-oriented approach, middleware-oriented approach, service-oriented approach, or PaaS-oriented approach. Various SaaS customization strategies can be used from light customization with manual coding to heavy customization where the SaaS system and its underlying PaaS systems are customized together. Multi-tenancy architecture is an important feature of a SaaS and various trade-offs including security isolation, performance, and engineering effort need to be considered. It is important for a SaaS system to have multi-level redundancy and recovery mechanisms, and the SaaS system needs to coordinate these with the underlying PaaS system. Finally, SaaS scalability mechanisms include a multi-level architecture with load balancers, automated data migration, and software design strategies.

iMashup: a mashup-based framework for service composition

Abstract: The Web has undergone a tremendous change from a primarily publication platform towards a participatory and “programmable” platform, where a large number of heterogeneous Web-delivered services (including SOAP and RESTful Web services, RSS and Atom feeds) are emerging. It results in the creation of Web mashup applications with rich user experiences. However, the integration of Web-delivered services is still a challenging issue. It not only requires the developers’ tedious efforts in understanding and coordinating heterogeneous service types, but also results in the time-consuming development of user interfaces. In this paper, we propose the iMashup composition framework to facilitate mashup development and deployment. We provide a unified mashup component model for the common representation of heterogeneous Web-delivered service interfaces. The component model specifies necessary properties and behaviors at both business and user interface level. We associate the component model with semantically meaningful tags, so that mashup developers can fast understand the service capabilities. The mashup developers can search and put the proper mashup components into the Web browser based composition environment, and connect them by data flows based on the tag-based semantics. Such an integration manner might prevent some low-level programming efforts and improve the composition efficiency. A series of experimental study are conducted to evaluate our framework.

Fuzziness parameter selection in fuzzy c-means: The perspective of cluster validation

Abstract: Fuzzy c-means (FCM) algorithm is an important clustering method in pattern recognition, while the fuzziness parameter, m, in FCM algorithm is a key parameter that can significantly affect the result of clustering. Cluster validity index (CVI) is a kind of criterion function to validate the clustering results, thereby determining the optimal cluster number of a data set. From the perspective of cluster validation, we propose a novel method to select the optimal value of m in FCM, and four well-known CVIs, namely XB, VK, VT, and SC, for fuzzy clustering are used. In this method, the optimal value of m is determined when CVIs reach their minimum values. Experimental results on four synthetic data sets and four real data sets have demonstrated that the range of m is [2, 3.5] and the optimal interval is [2.5, 3].

Adaptive fuzzy tracking control for a class of uncertain MIMO nonlinear systems using disturbance observer

Abstract: In this paper, the adaptive fuzzy tracking control is proposed for a class of multi-input and multioutput (MIMO) nonlinear systems in the presence of system uncertainties, unknown non-symmetric input saturation and external disturbances. Fuzzy logic systems (FLS) are used to approximate the system uncertainty of MIMO nonlinear systems. Then, the compound disturbance containing the approximation error and the time-varying external disturbance that cannot be directly measured are estimated via a disturbance observer. By appropriately choosing the gain matrix, the disturbance observer can approximate the compound disturbance well and the estimate error converges to a compact set. This control strategy is further extended to develop adaptive fuzzy tracking control for MIMO nonlinear systems by coping with practical issues in engineering applications, in particular unknown non-symmetric input saturation and control singularity. Within this setting, the disturbance observer technique is combined with the FLS approximation technique to compensate for the effects of unknown input saturation and control singularity. Lyapunov approach based analysis shows that semi-global uniform boundedness of the closed-loop signals is guaranteed under the proposed tracking control techniques. Numerical simulation results are presented to illustrate the effectiveness of the proposed tracking control schemes.

Lattice-based Key Exchange on Small Integer Solution problem

Abstract: In this paper, we propose a new hard problem, called bilateral inhomogeneous small integer solution (Bi-ISIS), which can be seen as an extension of the small integer solution problem on lattices. The main idea is that, instead of choosing a rectangle matrix, we choose a square matrix with small rank to generate Bi-ISIS problem without affecting the hardness of the underlying SIS problem. Based on this new problem, we present two new hardness problems: computational Bi-ISIS and decisional problems. As a direct application of these problems, we construct a new lattice-based key exchange (KE) protocol, which is analogous to the classic Diffie- Hellman KE protocol. We prove the security of this protocol and show that it provides better security in case of worst-case hardness of lattice problems, relatively efficient implementations, and great simplicity.

A flexible capacitive tactile sensor array with micro structure for robotic application

Abstract: A flexible capacitive tactile sensor array with micro needle structure is proposed in this paper for robotic application. Micro needle layer made of polydimethylsiloxane (PDMS) is sandwiched between the upper electrode layer made of PDMS and the bottom electrode layer fabricated on polyester (PET) film. The PDMS material renders the device adequate flexibility as it can be rolled into a cylinder. The single cell size in the fabricated 4 × 4 sensors array is 0.7 × 0.5 cm2 and the initial capacitance of each cell is 0.86 pF. The fabricated cell shows a sensitivity of 3.26%/mN within the full scale range of 1 kPa. The micro needle structure gives better repeatability and stability. The maximum error during each measurement is about 3.2%, while the minimum error is about 1.2%.

Temporal evolution of contacts and communities in networks of face-to-face human interactions

Abstract: Temporal dynamics of social interaction networks as well as the analysis of communities are key aspects to gain a better understanding of the involved processes, important influence factors, their effects, and their structural implications. In this article, we analyze temporal dynamics of contacts and the evolution of communities in networks of face-to-face proximity. As our application context, we consider four scientific conferences. On a structural level, we focus on static and dynamic properties of the contact graphs. Also, we analyze the resulting community structure using state-of-the-art automatic community detection algorithms. Specifically, we analyze the evolution of contacts and communities over time to consider the stability of the respective communities. Furthermore, we assess different factors which have an influence on the quality of community prediction. Overall, we provide first important insights into the evolution of contacts and communities in face-to-face contact networks.

A high speed 1000 fps CMOS image sensor with low noise global shutter pixels

Abstract: A low read noise 8T global shutter pixel for high speed CMOS image sensor is proposed in this paper. The pixel has a pixel level sample-and-hold circuit and an in-pixel amplifier whose gain is larger than one. Using pixel level sample-and-hold circuit, the KTC noise on FD node can be effectively cancelled by correlated double sampling operation. The in-pixel amplifier with a gain larger than one is employed for reducing the pixel level sample-and-hold capacitors thermal noise and their geometric size. A high speed 1000 fps 256×256 CMOS image sensor based on the pixel is implemented in 0.18 μm CMOS process. The chip active area is 5 mm×7 mm with a pixel size of 14 μm×14 μm. The developed sensor achieves a read noise level as low as 14.8e- while attaining a high fill factor of 40%. The full well capacity can contain 30840e- and the resulting signal dynamic range is 66 dB.

Exact Safety Verification of Hybrid Systems Using Sums-Of-Squares Representation

Abstract: In this paper we discuss how to generate inductive invariants for safety verification of hybrid systems. A hybrid symbolic-numeric method is presented to compute inequality inductive invariants of the given systems. A numerical invariant of the given system can be obtained by solving a parameterized polynomial optimization problem via sum-of-squares (SOS) relaxation. And a method based on Gauss-Newton refinement and rational vector recovery is used to obtain the invariants with rational coefficients, which exactly satisfy the conditions of invariants. Several examples are given to illustrate our algorithm.

Trace representation and linear complexity of binary sequences derived from Fermat quotients

Abstract: We describe the trace representations of two families of binary sequences derived from the Fermat quotients modulo an odd prime p (one is the binary threshold sequences and the other is the Legendre Fermat quotient sequences) by determining the defining pairs of all binary characteristic sequences of cosets, which coincide with the sets of pre-images modulo p 2 of each fixed value of Fermat quotients. From the defining pairs, we can obtain an earlier result of linear complexity for the binary threshold sequences and a new result of linear complexity for the Legendre Fermat quotient sequences under the assumption of 2 p−1 ≢ 1 mod p 2.

Approximation-based adaptive fuzzy control for a class of non-strict-feedback stochastic nonlinear systems

Abstract: This paper considers the problem of adaptive fuzzy control of a class of single-input/single-output (SISO) nonlinear stochastic systems in non-strict-feedback form. Fuzzy logic systems are used to approximate the uncertain nonlinearities and backstepping technique is utilized to construct an adaptive fuzzy controller. The proposed controller guarantees that all the signals in the resulting closed-loop system are bounded in probability. The main contribution of this note lies in providing a control strategy for a class of nonlinear systems in non- strict-feedback form. Simulation result is used to test the effectiveness of the suggested approach.

Controllability of Boolean control networks avoiding states set

Abstract: In this paper, using semi-tensor product and the vector form of Boolean logical variables, the Boolean control network (BCN) is expressed as a bilinear discrete time system about state and control variables. Based on the algebraic form, the reachability and controllability avoiding undesirable states set are discussed. The reachability and controllability discussed here are under certain constraint and the definitions of reachability and controllability avoiding undesirable states set have practical meaning. Also, the necessary and sufficient conditions for reachability and controllability are given. At last, the control sequence that steers one state to another is constructed.

Adaptive neural network tracking design for a class of uncertain nonlinear discrete-time systems with dead-zone

Abstract: In this paper, the stability and control issues of a class of uncertain nonlinear discrete-time systems in the strict feedback form are investigated. The dead-zone input in the systems, whose property is non-symmetric and discretized, is investigated. The unknown functions in the systems are approximated by using the radial basis function neural networks (RBFNNs). Backstepping design procedure is employed in the controller and the adaptation laws design. Lyapunov analysis method is utilized to prove the stability of the closed-loop system. A simulation example is given to illustrate the effectiveness of the proposed approach.

Human control model in teleoperation rendezvous

Abstract: This paper proposes a human control model in teleoperation rendezvous on the basis of human information processing (perception, judgment, inference, decision and response). A predictive display model is introduced to provide the human operator with predictive information of relative motion. By use of this information, the longitudinal and lateral control models for the operator are presented based on phase plane control method and fuzzy control method, and human handling qualities are analyzed. The integration of these two models represents the human control model. Such a model can be used to simulate the control process of the human operator, which teleoperates the rendezvous with the aid of predictive display. Experiments with human in the loop are carried out based on the semi-Physical simulation system to verify this human control model. The results show that this human control model can emulate human operators’ performance effectively, and provides an excellent way for the analysis, evaluation and design of the teleoperation rendezvous system.

Low power adiabatic logic based on FinFETs

Abstract: With the aggressive scaling of device technology, the leakage power has become the main part of power consumption, which seriously reduces the energy recovery efficiency of adiabatic logic. In this paper, a novel low-power adiabatic logic based on FinFET devices has been proposed. Due to the lower leakage current, higher on-state current and design flexibility of FinFETs, the proposed adiabatic logic shows considerable power reduction, performance improvement and area saving compared with CMOS adiabatic logic. An 8-state clock chain as the test circuit has been demonstrated based on the 32-nm FinFET Predictive Technology Model. The simulation results show that adiabatic circuit based on FinFET devices achieves a power reduction of up to 84.8% and a limiting frequency of up to 55 GHz.

Load diversity based optimal processing resource allocation for super base stations in centralized radio access networks

Abstract: To reduce construction cost and energy consumption of cellular networks, the centralized radio access cellular network infrastructure with a Super BS (CSBS) architecture has been proposed. The CSBS architecture has the advantage that the centralized processing resource can be flexibly organized. However, the problem of low processing resource efficiency caused by load discrepancy of base stations still exists and the processing resource allocation methods for physical layer processing are not suitable for protocol processing. In this article, a framework for protocol processing resource management is designed and a load diversity based processing resource allocation (LDA) algorithm is proposed, which employs dynamic programming with the consideration of load discrepancy. Also, to support large mumber of BSs, a suboptimal algorithm hybrid load diversity based processing resource allocation (H-LDA) is also proposed. Simulation results show that LDA and H-LDA algorithm significantly outperforms the conventional methods, respectively, by more than 60% and 55% in the processing resource efficiency and the performance gap grows with the increasing BS number.

Small universal simple spiking neural P systems with weights

Abstract: Spiking neural P systems with weights (WSN P systems, for short) are a new variant of spiking neural P systems, where the rules of a neuron are enabled when the potential of that neuron equals a given value. It is known that WSN P systems are universal by simulating register machines. However, in these universal systems, no bound is considered on the number of neurons and rules. In this work, a restricted variant of WSN P systems is considered, called simple WSN P systems, where each neuron has only one rule. The complexity parameter, the number of neurons, to construct a universal simple WSN P system is investigated. It is proved that there is a universal simple WSN P system with 48 neurons for computing functions; as generator of sets of numbers, there is an almost simple (that is, each neuron has only one rule except that one neuron has two rules) and universal WSN P system with 45 neurons.

Fabrication of strongly adherent platinum black coatings on microelectrodes array

Abstract: Platinum black coating can effectively improve the performance of MEAs (microelectrodes array) in neural signal transduction, though its lack of adhesion strength and durability tampers its usage in long term experiments. Here a new method of composite electrodeposition provides highly adhesive platinum black coating that enables MEAs for a month’s long task and repeatable utilization. The new method was compared with present techniques on multiple aspects, e.g. actual surface area, surface morphology, interfacial impedance, durability and real application tests. Results show that the new composite coating provides greatly improved durability without compromising its performances. Neural cells were cultured on these MEAs for 40 days in vitro and spontaneous action potentials with high signal/noise ratio were recorded. Theoretical model and simulation provided preliminary understanding on the mechanism of this strengthened platinum black coating.

Cluster synchronization of a class of multi-agent systems with a bipartite graph topology

Abstract: This paper investigates cluster synchronization of a class of multi-agent systems with a directed bipartite graph topology, and presents a number of new results by using the neighbor’s rules for the following two cases: I) there is competition among the agents of different clusters, and II) there are both competition and cooperation among the agents. Firstly, for case I), a linear control protocol is designed for cluster synchronization of multi-agent systems, and a method is presented to determine the final state with the initial conditions based on state-space decomposition. Secondly, we study case II), and design a control protocol based on the information of neighbors and that of two-hop neighbors (that is, neighbors’ neighbors). Finally, two examples are studied by using our presented results. The study of illustrative examples with simulations shows that our results as well as designed control protocols work very well in studying the cluster synchronization of this class of multi-agent systems.

Novel way to research nonlinear feedback shift register

Abstract: In this paper, we regard the nonlinear feedback shift register (NLFSR) as a special Boolean network, and use semi-tensor product of matrices and matrix expression of logic to convert the dynamic equations of NLFSR into an equivalent algebraic equation. Based on them, we propose some novel and generalized techniques to study NLFSR. First, a general method is presented to solve an open problem of how to obtain the properties (the number of fixed points and the cycles with different lengths) of the state sequences produced by a given NLFSR, i.e., the analysis of a given NLFSR. We then show how to construct all $$2^{2^n - (l - n)} /2^{2^n - l}$$ shortest n-stage feedback shift registers (nFSR) and at least $$2^{2^n - (l - n) - 1} /2^{2^n - l - 1}$$ shortest n-stage nonlinear feedback shift registers (nNLFSR) which can output a given nonperiodic/periodic sequence with length l. Besides, we propose two novel cycles joining algorithms for the construction of full-length nNLFSR. Finally, two algorithms are presented to construct $$2^{2^{n - 2} - 1}$$ different full-length nNLFSRs, respectively.

Developer social networks in software engineering: construction, analysis, and applications

Abstract: With the increasing popularity of Internet, more and more developers are collaborating together for software development. During the collaboration, a lot of information related to software development, including communication and coordination information of developers, can be recorded in software repositories. The information can be employed to construct Developer Social Networks (DSNs) for facilitating tasks in software engineering. In this paper, we survey recent advances of DSNs and examine three fundamental steps of DSNs, namely construction, analysis, and applications. We summarize the state-of-the-art methods in the three steps and investigate the relationships among them. Furthermore, we discuss the main issues and point out the future opportunities in the study of DSNs.

Novel silicon-controlled rectifier (SCR) for digital and high-voltage ESD power supply clamp

Abstract: Due to latch-up issue, the main problem of silicon-controlled rectifier (SCR) for power supply clamps in on-chip ESD protection is its inherent low holding voltage, especially in high-voltage applications. In this paper, we proposed a MOS-inside SCR (MISCR) showing nearly no snapback character and good ESD robustness, which is qualified for on-chip power clamp ESD protection. The stacked device achieves a series of triggering and holding voltage by altering the stacking number, which can also be used for the high voltage ESD power supply clamp applications.

The relationship between physical human-exoskeleton interaction and dynamic factors: using a learning approach for control applications

Abstract: During a human-exoskeleton collaboration, the interaction torque on exoskeleton resulting from the human cannot be clearly determined and conducted by normal physical models. This is because the torque depends not only on direction and orientation of both human-operator and exoskeleton but also on the physical properties of each operator. In this paper, we present our investigations on the relationship between the interaction torques with the dynamic factors of the human-exoskeleton systems using state-of-the-art learning techniques (nonparametric regression techniques) and provide control applications based on the findings. Experimental data was collected from various human-operators when they were attached to the designed exoskeleton to perform unconstraint motions with and without control. The results showed that regardless of how the experiments were done and which learning method was chosen, the resulting interaction could be best represented by time varying non-linear mappings of the operator's angular position, and the exoskeleton's angular position, velocity, and acceleration during locomotion. This finding has been applied to advanced controls of the lower exoskeletal robots in order to improve their performance while interacting with human.

Two kinds of optimal controls for probabilistic mix-valued logical dynamic networks

Abstract: This paper addresses two kinds of optimal control problems of probabilistic mix-valued logical control networks by using the semi-tensor product of matrices, and presents a number of new results on the optimal finite-horizon control and the first-passage model based control problems, respectively. Firstly, the probabilistic mix-valued logical control network is expressed in an algebraic form by the semi-tensor product method, based on which the optimal finite-horizon control problem is studied and a new algorithm for choosing a sequence of control actions is established to minimize a given cost functional over finite steps. Secondly, the first-passage model of probabilistic mix-valued logical networks is given and a new algorithm for designing the optimal control scheme is proposed to maximize the corresponding probability criterion. Finally, an illustrative example is studied to support our new results/algorithms.