Showing papers in "International Journal of Computers Communications & Control in 2008"
TL;DR: This work adds to tissue P systems the basic feature of (cell–like) P systems with active membranes – the possibility to divide cells, and gets the possibility of solving computationally hard problems in polynomial time.
Abstract: In tissue P systems several cells (elementary membranes) communicate through symport/antiport rules, thus carrying out a computation. We add to such systems the basic feature of (cell–like) P systems with active membranes – the possibility to divide cells. As expected (as it is the case for P systems with active membranes), in this way we get the possibility to solve computationally hard problems in polynomial time; we illustrate this possibility with SAT problem.
99 citations
TL;DR: Using the ability of ANFIS (Adaptive Neuro-Fuzzy Inference System) to learn from training data, it is possible to create ANF IS, an implementation of a representative fuzzy inference system using a BP neural network-like structure, with limited mathematical representation of the system.
Abstract: Obtaining the joint variables that result in a desired position of the robot end-effector called as inverse kinematics is one of the most important problems in robot kinematics and control. As the complexity of robot increases, obtaining the inverse kinematics solution requires the solution of non linear equations having transcendental functions are difficult and computationally expensive. In this paper, using the ability of ANFIS (Adaptive Neuro-Fuzzy Inference System) to learn from training data, it is possible to create ANFIS, an implementation of a representative fuzzy inference system using a BP neural network-like structure, with limited mathematical representation of the system. Computer simulations conducted on 2 DOF and 3DOF robot manipulator shows the effectiveness of the approach.
93 citations
TL;DR: A neural approach to derive different models describing the process in different operating conditions by using an adequate Kohonen self-organizing neural network to determination of the models and of the adequate method of validities computation.
Abstract: The multimodel approach was recently developed to deal with the issues of complex processes modeling and control. Despite its success in different fields, it still faced with some design problems, and in particular the determination of the models and of the adequate method of validities computation. In this paper, we propose a neural approach to derive different models describing the process in different operating conditions. The implementation of this approach requires two main steps. The first step consists in exciting the system with a rich (e.g. pseudo random) signal and collecting measurements. These measurements are classified by using an adequate Kohonen self-organizing neural network. The second step is a parametric identification of the base-models by using the classification re- sults for order and parameters estimation. The suggested approach is implemented and tested with two processes and compared to the classical modeling approach. The obtained results turn out to be satisfactory and show a good precision. These also allow to draw some interpretations about the adequate validities' calculation method
30 citations
TL;DR: A generic model of a transport management system, based on the decision model of an operator, and the traveler information system are proposed and used to elaborate a traffic regulation system in the case of a bimodal transportation system (tram-bus).
Abstract: As they involve many interacting agents behaving in numerous ways that are extremely difficult to predict, urban transportation systems are complex in nature. The development of intermodal passenger transportation solutions to address the mobility issues constitutes a major thrust area of urban transport policies. But, to offer citizens comprehensive seamless mobility, intermodal transportation system management (ITSM) requires the integration of two major components. The traffic regulation support system, to help the operator responsible for the regulation tasks: coordination of timetables, synchronising arrival and departure times between the different transportation modes, and the traveller information system, giving customers access to information and using a comprehensive set of information tools. In this paper, a generic model of a transport management system, integrating these two components is proposed. This generic model is then used to elaborate a traffic regulation system in the case of a bimodal transportation system (tram-bus). The traffic regulation support system, based on the decision model of an operator, and the traveler information system are described.
29 citations
TL;DR: The use of Hyper- heuristics built on top of hybridized Metaheuristics to efficiently and effectively schedule jobs onto available resources in a grid environment thus resulting in an optimal schedule with minimum makespan is emphasized.
Abstract: Efficient execution of computations in grid can require mapping of tasks to processors whose performance is both irregular and time varying because of dynamic nature. The task of mapping jobs to the available computing nodes or scheduling of the jobs on the grid is a NP complete problem. The NP-hard problem is often solved using heuristics techniques. Heuristic and metaheuristic approaches tend to be knowledge rich, requiring substantial expertise in both the problem domain and appropriate heuristics techniques. To alleviate this problem the concept of Hyperheuristic was introduced. They operate on the search space of heuristics instead of candidate solutions and can be applied to any optimization problem. This paper emphasizes the use of Hyper-heuristics built on top of hybridized Metaheuristics to efficiently and effectively schedule jobs onto available resources in a grid environment thus resulting in an optimal schedule with minimum makespan.
26 citations
TL;DR: This method is effective and robust in multiple cases even for a typical signal showing undetermined GOIs and multiple peaks at GCIs, and applies cubic root amplitude on the product to improve the representation of weak amplitudes.
Abstract: This paper deals with glottal parameter estimation such as local pitch and open quotient from electroglottographic signal (EGG). This estimation is based on glottal closing instants and glottal opening instants determined by a multi-scale product of this signal. Wavelet transform of EGG signal is made with a quadratic spline function. Wavelet coefficients calculated on different dyadic scales, show modulus maxima at localized discontinuities of EGG signal. The detected maxima and minima correspond to the glottal opening and closing instants called GOIs and GCIs. To improve the estimate precision, we operate the multi-scale product of wavelet transform coefficients of three successive dyadic scales. This processing enhances edge detection. A Multi-scale product is a nonlinear combination of successive scales; it reduces noise and spurious peaks. We apply cubic root amplitude on the product to improve the representation of weak amplitudes. The method has a good representation of GCI and a best detection of GOI. The method was tested on the Keele University database; it is effective and robust in multiple cases even for a typical signal showing undetermined GOIs and multiple peaks at GCIs. Finally precise measurement of these instants allows accurate estimation of prosodic parameters as local pitch and open quotient.
23 citations
TL;DR: This paper provides an approach for the application of PID controllers within a cascade control system configuration based on considerations about the expected operating modes of both controllers, and chooses a tuning that provides a balanced set-point / load-disturbance performance.
Abstract: This paper provides an approach for the application of PID controllers within a cascade control system configuration. Based on considerations about the expected operating modes of both controllers, the tuning of both inner and outer loop controllers are selected accordingly. This fact motivates the use of a tuning that, for the secondary controller, provides a balanced set-point / load-disturbance performance. A new approach is also provided for the assimilation of the inner closed-loop transfer function to a suitable form for tuning of the outer controller. Due to the fact that this inevitably introduces unmodelled dynamics into the design of the primary controller, a robust tuning is needed.
17 citations
TL;DR: Predictive Functional Control alone is simpler to tune and can exhibit comparable performances, except that the controller is more sensitive to nonlinear phenomena such as dry friction, which were not taken into account into the model and generate a static error.
Abstract: Different predictive control strategies have been validated on a DC motor. ICascaded predictive control, which consists of a cascaded loop where the traditional servo algorithms are replaced by PFCs, could enhance the cycle time. Predictive Functional Control alone is simpler to tune and can exhibit comparable performances, except that the controller is more sensitive to nonlinear phenomena such as dry friction, which were not taken into account into the model and generate a static error.
17 citations
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TL;DR: This work combines the fuzzy systems with the sliding mode control technique to compute at each sampling time the control law, which comports two terms: equivalent control law and switching control law which has a high frequency.
Abstract: In this work we are interested to discrete robust fuzzy sliding mode control. The discrete SISO nonlinear uncertain system is presented by the Takgi- Sugeno type fuzzy model state. We recall the principle of the sliding mode control theory then we combine the fuzzy systems with the sliding mode control technique to compute at each sampling time the control law. The control law comports two terms: equivalent control law and switching control law which has a high frequency. The uncertainty is replaced by its upper bound. Inverted pendulum and mass spring dumper are used to check performance of the proposed fuzzy robust sliding mode control scheme.
17 citations
TL;DR: This work surveys and analyzes selected literature on important role of natural computing aspects, such as emergence (using swarm intelligence to achieve collective intelligence) and emotion, to virtual learning, and proposes using infrastructural support for virtual learning through system learning.
Abstract: Virtual learning is not just about a set of useful IT tools for learning. From an examination on where virtual learning stands in the overall learning spectrum, we point out the important impact of natural computing on virtual learning. We survey and analyze selected literature on important role of natural computing aspects, such as emergence (using swarm intelligence to achieve collective intelligence) and emotion, to virtual learning. In addition, in order to effectively incorporate these aspects into virtual learning, we propose using infrastructural support for virtual learning through system learning: The virtual learning environment not only provides facilities for learners, but also observes the behavior of learners and takes actions, so that its own performance can be improved (i.e., to better serve the learners). In this sense, system learning is concerned with learning about learners. Consequently, a virtual learning environment is a true human-machine symbiosis, paired by human learning and system learning.
16 citations
TL;DR: The paper presents the tradeoffs involved in the circuit design and the design for performance issues and shows that DPA resistivity of SABL implementation of both stream ciphers has a major improvement.
Abstract: The threat of DPA attacks is of crucial importance when designing cryptographic hardware. This contribution discusses the DPA-resistant implementation of two eSTREAM finalists using SABL logic styles. Particularly, two Feedback Shift Register (FSR) based stream ciphers, Grain v.1 and Trivium are designed in both BSim3 130nm and typical 350nm technologies and simulated by HSpice software. Circuit simulations and statistical power analysis show that DPA resistivity of SABL implementation of both stream ciphers has a major improvement. The paper presents the tradeoffs involved in the circuit design and the design for performance issues.
TL;DR: A dynamic key management model for satellite networks (DKM-SN) is presented, which includes certificates owned by each satellite, primary keys and session keys both of which are shared between two satellites, and a protocol is designed for updating certificates for satellites.
Abstract: Satellite networks are becoming increasingly important because of the ex- citing global communication services they provide. Key management policies have been successfully deployed in terrestrial networks to guarantee the information se- curity. However, long propagation, storage and computation constraints bring new challenges in designing efficient and cost-effective key updating policies for satellite networks. Based on the structure and communication features of satellite networks, a dynamic key management model for satellite networks (DKM-SN) is presented, which includes certificates owned by each satellite, primary keys and session keys both of which are shared between two satellites. Furthermore, a protocol is designed for updating certificates for satellites; different policies for updating primary and ses- sion keys are studied and their efficiency and security are analyzed and compared. In addition, simulation environment for satellite networks is built and the key updat- ing processes are implemented in Walker constellation. From the simulation results, further contrasts on key updating time and storage costs between the applications of IBM hybrid key management model (HKMM) and DKM-SN in satellite networks are presented. Finally, important suggestions in designing key updating policies are Satellite networks are composed of various kinds of communication satellites, vehicles and constel- lations. It contains both satellite-to-satellite and satellite-to-ground links. Satellite networks integrate terrestrial systems and all sorts of satellites which are deployed in different orbits with diverse tasks. Nowadays, satellite networks are increasingly used in the long-distance information transmission ser- vices. In order to ensure the message confidentiality, integrity and nonrepudiation, as well as efficiency of communication, a key management mechanism should be used to provide data encryption, authenti- cation and key distribution and updating services for satellite communication. Key management model defines the entities in the services, the categories and relationships of the keys, and the key updating protocols and algorithms. In contrast with terrestrial networks, satellite networks are subject to dynamic network topology, long propagation delay, as well as low computing and storage capabilities of satellites. Due to these constraints, efforts should be made to decrease the key updating time in order to reduce the communication cost. Besides, for those keys used to encrypt large amount of information, the key up- dating protocols should be based on symmetric encryption techniques for the sake of computation cost. The storage cost on satellites should also be reduced by efficiently lowering the number of the keys. Currently, key management policies for terrestrial networks are comparatively sophisticated. There are generally three kinds of key management policies, including those that use symmetric key encryption techniques, public key encryption techniques and combination of the two. For example, Kerberos (1) uses symmetric key encryption techniques and a KDC (Key Distribution Center); both symmetric and public key encryption techniques are adopted in IBM hybrid key management model (HKMM) in which three kinds of keys including session key, primary key and public key are used. Based on different net- work features and environments, the number of entities and encryption techniques involved in updating a certain type of key may be very different. For instance, though both for updating the session key, Neuman-Stubblebine protocol (3) includes three parties while Janson-Tsudik protocol (4) involves only
TL;DR: An evolutionary (genetic) algorithm is used to deal with the multi-criteria optimization problem of the disassembly scheduling and it is found that a well balanced line will decrease the cost of disassembly operations.
Abstract: Disassembly is part of the demanufacturing and it is meant to obtain components and materials from end-of-life products. An essential performance objective of a disassembly process is the benefits it brings, that is the revenue brought by the retrieved parts and material, diminished by the cost of their retrieval operations. A decision must be taken to balance an automatic disassembly line. A well balanced line will decrease the cost of disassembly operations. An evolutionary (genetic) algorithm is used to deal with the multi-criteria optimization problem of the disassembly scheduling.
TL;DR: This paper describes the results of experiments for surface roughness image acquisition and processing in order to develop an automated roughness control system using quasi-fractal characteristics and fuzzy clustering to achieve this goal.
Abstract: In this paper the authors describe the results of experiments for surface roughness image acquisition and processing in order to develop an automated rough- ness control system. This implies the finding of a characteristic roughness parameter (for example Ra) on the bases of information contained in the image of the surface. To achieve this goal we use quasi-fractal characteristics and fuzzy clustering meth- ods.
TL;DR: The system design of a e-learning method that can be directly used for e- learning purposes regarding the spatial topology, the history, the architecture, the structure and the temporal (time-based) 3-D geometry of the projected object, scene or procedure is presented.
Abstract: The rapid advances in learning technologies, computer modeling, multimedia and spatial sciences, as well as the availability of many powerful graphics PCs and workstations, make 3-D modeling-based methods for personalized e-learning with eCAD (modeling) functionality feasible. Personalized eCAD learning is a new term in engineering, environment and architecture education, related to the development of learning educational units (3-D learning objects) with re-usable digital architecture functionality, and introduced to literature for the first time within this paper. In particular, for university education courses in eCAD, digital architecture, design computing and CAAD (reagarding spatial information systems, architectures, monuments, cultural heritage sites, etc.), such a e-learning methodolgy must be able to derive spatial, pictorial, geometric, spatial, topological, learning and semantic information from the target object (a 3-D model) or scene (a 3-D landscape environment) or procedure (a 3-D simulation approach to a phenomenon), in such a way that it can be directly used for e-learning purposes regarding the spatial topology, the history, the architecture, the structure and the temporal (time-based) 3-D geometry of the projected object, scene or procedure. This paper is about the system design of such a e-learning method. For this purpose, the requirements, objectives and pedagogical extensions are presented and discussed. Finaly, a practical project is used to demonstrate the functionality and the performance of the proposed methodology in architecture
TL;DR: The relative weakness of the IJCCC resides in the citation issue measured by its impact factor, however, as IJCC is a new journal, no citation history exists to date.
Abstract: As of the production of its third volume, issue 3, year 2008, the Journal of Computers, Communications & Control (IJCCC) entered a new era. I was pleasantly surprised when in March, 2008, a message arrived from Ioan Dzitac, the Associate Editor-in-Chief of IJCCC, notified me about the inclusion of this new periodical in the prestigious Master Journal List of Thomson Reuters Database. Two months later, more pleasant news came: IJCCC was covered in Science Citation Index Expanded (also known as SciSearch) as its quality figure of merit. This incredible achievement is emphasized by the journal’s age. Started in 2006 as a quarterly peer-reviewed periodical, this almost new-born journal knew an increased interest ever since, due to its increasing quality over this short time period. To ensure high publication quality, all published manuscripts passed through a peer-review process. This process provides authors with valuable critiques of their work by at least three independent experts in the topic field of their manuscripts, helping the editors to assess the scientific and technical merit of the work described. We are all aware of the Thomson Scientific Journal selection process and how selective this is. Several factors are considered and have to be fulfilled when evaluating journals for coverage, including the publication timeliness, editorial content, international diversity, citation analysis and, finally, the journal’s electronic format. Out of these, the relative weakness of the IJCCC resides in the citation issue measured by its impact factor. However, as IJCC is a new journal, no citation history exists to date. For the future, a special attention shall be paid to this issue as its value is a strong indicator related to the journal’s importance and popularity in its scientific field.
TL;DR: This paper presents the acquired experience in the development and use of multimedia contents for e-learning applications, created for some of the subjects of the degree in computer science engineering.
Abstract: In the same manner that e-learning applications are becoming increasingly important at the university, there are still some critical questions that should be solved with the objective of making use of the potential offered by currentWeb Technologies. The creation of contents that are able of capturing the attention of interest of the students and their disposal in an appropriate way constitute the main purpose of this work. The teaching content engineering expounded shows the different stages that should form part of the process. A development team, composed of different professional profiles, will work together with the lecturers of the subject to which the contents are been created, i.e. multimedia videos and interactive applications. This process should be developed according to a methodology that assure the use of appropriate resources, all that tasks -suitable of being- should be modularized and factorized. This paper presents the acquired experience in the development and use of multimedia contents for e-learning applications, created for some of the subjects of the degree in computer science engineering. The deliveries of these contents make use of Internet and video streaming techniques. The result of the work shows the students satisfaction, including their comments.
TL;DR: The work stated here provides two on-line scheduling algorithms, namely RLP and RLP/T, which enhance the existing Skip-Over algorithms, which aim at improving the actual QoS observed for periodic tasks (which is always greater or equal to the QoS guarantee).
Abstract: In this paper, we deal with dynamic scheduling components integrating new Quality of Service (QoS) functionalities into a Linux-based real-time operating system. In our approach, periodic tasks allow occasional deadline violations within given bounds specified according to the Skip-Over task model. Hence, every task has a minimal QoS guarantee which is expressed by the ratio of periodic task instances which must complete before their deadline. The work stated here provides two on-line scheduling algorithms, namely RLP and RLP/T, which enhance the existing Skip-Over algorithms. More specifically, the proposed algorithms aim at improving the actual QoS observed for periodic tasks (which is always greater or equal to the QoS guarantee). These novel scheduling techniques rely on the EDL (Earliest Deadline as Late as possible) scheduling strategy. Simulation results show the performance of RLP and RLP/T with respect to basic Skip-Over algorithms. Finally, we present the integration of these QoS scheduling services into CLEOPATRE open-source component library, a patch to Linux/RTAI.
TL;DR: This paper deals with a feedback gain design method for the full-order flux observer with adaptive speed loop, which enables the minimizing the unstable operation region of this observer to a line in the torque-speed plane.
Abstract: This paper deals with a feedback gain design method for the full-order flux observer with adaptive speed loop, which enables the minimizing the unstable operation region of this observer to a line in the torque-speed plane. The stability in regenerating mode is studied using necessary condition of stability based on determinant of matrix and a linearized model. Simulations results where the proposed observer is compared with an exiting solution (where the unstable region is not totally removed) are presented to validate the proposed observer design.
TL;DR: An improved certificateless signature scheme (McCLS) based on bilinear pairings is presented that is more efficient than existing CLS solutions, and results from empirical studies show that the McDV is able to resist the two common attacks without causing substantial degradation of the network performance.
Abstract: Mobile Ad Hoc Network is a self-configurable and self-organizing wireless network of mobile devices without fixed infrastructure support, which makes it a good candidate as underlying communication network for the Cyber-Physical Systems in emergency conditions such as earthquake, flood, and battlefields. In these scenarios, efficient communication schemes with security support are especially desired. Two cryptography approaches, the public key cryptography and the identitybased cryptography, face the costly and complex key management problem and the “key escrow" problem in the real-life deployment. Recently, the certificateless public key cryptography (CL-PKC) was introduced to address these problems in previous approaches. However, the efficiency of the schemes based on CL-PKC is not high and can be improved further. In this paper, we present an improved certificateless signature scheme (McCLS) based on bilinear pairings. First, we theoretically compare the efficiency of McCLS with that of existing certificateless signature schemes (CLS). Second, an empirical study is conducted to compare the traditional AODV with the McCLS scheme based on AODV (McDV) in their efficiency and effectiveness against two most common attacks (i.e. redirection attack and rushing attack). Results from theoretical analysis show that the new McCLS scheme is more efficient than existing CLS solutions, and results from empirical studies show that the McDV is able to resist the two common attacks without causing substantial degradation of the network performance.
TL;DR: A solution to solve the libraries usefulness for parallel computing is presented that provides the same functionality as the original Mobile MPI library, but implemented over a Bluetooth scatternet.
Abstract: The Mobile Message Passing Interface is a library which implements MPI functionality on Bluetooth enabled mobile phones. It provides many of the functions available in MPI, including point-to-point and global communication. The main restriction of the library is that it was designed to work over Bluetooth piconets. Piconet based networks provide for a maximum of eight devices connected together simultaneously. This limits the libraries usefulness for parallel computing. A solution to solve this problem is presented that provides the same functionality as the original Mobile MPI library, but implemented over a Bluetooth scatternet. A scatternet may be defined as a number of piconets interconnected by common node(s). An outline of the scatternet design is explained and its major components discussed.
TL;DR: An improved version of Ant Colony Optimisation (ACO) algorithm is adapted, mainly: the Elitist Ant System (EAS) algorithm in order to solve the Vehicle Route Allocation Problem (VRAP).
Abstract: Ant colonies are successfully used nowadays as multi-agent systems (MAS) to solve difficult optimization problems such as travelling salesman (TSP), quadratic assignment (QAP), vehicle routing (VRP), graph coloring and satisfiability problem. The objective of the research presented in this paper is to adapt an improved version of Ant Colony Optimisation (ACO) algorithm, mainly: the Elitist Ant System (EAS) algorithm in order to solve the Vehicle Route Allocation Problem (VRAP). After a brief introduction in the first section about MAS and their characteristics, the paper presents the rationale within the second section where ACO algorithm and its common extensions are described. In the approach (the third section) are explained the steps that must be followed in order to adapt EAS for solving the VRAP. The resulted algorithm is illustrated in the fourth section. Section five closes the paper presenting the conclusions and intentions.
TL;DR: This is the first paper describing the object-oriented modeling language, which contains fine- grained constructions, aimed to give a precise description of software components.
Abstract: This work is part of a series referring to COMDEVALCO - a framework for Software Component Definition, Validation, and Composition. Its constituents are: a modeling language, a component repository and a set of tools. This is the first paper describing the object-oriented modeling language, which contains fine- grained constructions, aimed to give a precise description of software components. The current status of the language reflects the procedural paradigm constructs.
TL;DR: A conceptual model for an Intelligent System built to support the scheduling for an underground mine in order to supervise its operation and the feasibility assessment of the Daily Master Plan based on the input data of the simulation model is presented.
Abstract: This paper presents a conceptual model for an Intelligent System built to support the scheduling for an underground mine in order to supervise its operation. The system is composed by a Simulation Model linked to a Knowledge Based System designed by means of hierarchical, colored and temporal Petri Nets. Simulation Model allows simulating the operation of the production, reduction and transport levels in the mine. Knowledge Based System is activated by events produced in daily operations and yields the results of registered events and the actions taken to solve the problem, generating operation rules. The proposed model allows different types of mine operations and scenarios providing data for decision-making. The system helps to evaluate different policies for programming the activities in the mine thus seeking to enlarge the equipment productivity. The model also allows the feasibility assessment of the Daily Master Plan based on the input data of the simulation model.
TL;DR: An adaptive controller to compensate the non- linear friction model when the output is the position is designed and an adaptive differential filter is presented to estimate the velocity.
Abstract: In this paper, we design an adaptive controller to compensate the non- linear friction model when the output is the position. First, we present an adaptive differential filter to estimate the velocity. Secondly, the dynamic friction force is compensated by a fuzzy adaptive controller with position measurements. Finally, a simulation result for the proposed controller is demonstrated.
Journal Article•
TL;DR: This communication provides an approach for the application of PID controllers within a cascade control system configuration based on considerations about the expected operating modes of both controllers, and proposes the use of a tuning that provides a balanced set-point / load-disturbance performance for the secondary controller.
Abstract: This communication provides an approach for the application of PID controllers within a cascade control system configuration. Based on considerations about the expected operating modes of both controllers, the tuning of both inner and outer loop controllers are selected accordingly. This fact motivates the use of a tuning that for the secondary controller that provides a balanced set-point / load-disturbance performance. A new approach is also provided for the assimilation of the inner closed-loop transfer function to a suitable form for tuning of the outer controller. Due to the fact that this inevitably introduces unmodelled dynamics into the design of the primary controller, a robust tuning is needed. The introduction and use of an additional sensor that allows for a separation of the fast and slow dynamics of the process results in a nested loop configuration as it is shown in figure (1). Each loop has associated its corresponding PID controller. The controller of the inner loop is called the secondary controller whereas the controller of the outer loop as the primary controller, being the output of the primary loop the variable of interest. The rationale behind this configuration is that the fast dynamics of the inner loop will provide faster disturbance attenuationandminimizethepossibleeffectdisturbancebeforetheyaffecttheprimaryoutput. Thissetupinvolves two controllers. It is therefore needed to tune both PIDs. The usual approach involves the tuning of the secondary controllerwhilesettingtheprimarycontrollerinmanualmode. Onasecondstep,theprimarycontrolleristunedby considering the secondary controller acting on the inner loop. It is therefore a more complicated design procedure than that of a standard single-loop based PID control system. In this paper a design issue that has not been addressed is considered: the tradeoff between the performance for set-point and load-disturbance response. When a load -disturbance occurs at the primary loop, the global load-disturbance depends on the set-point tracking performance of the secondary loop. In addition, good load- disturbance performance is expected for the secondary controller in order to attenuate disturbances that enter directly at the secondary loop. Also, it is well known that when the controller is optimally tuned for set-point response, the load-disturbance performance can be very poor (1). Based on this observation this paper proposes the use of a balanced performance tuning (2) for the secondary loop. Furthermore, an approximation procedure is provided in order to assimilate the dynamics seen by the primary controller to a First-Order-Plus-Time-Delay model such that usual tuning rules for PID control can be applied. However here a robust tuning is suggested, because,theprimarycontrollerwillneedtofacewithunmodelleddynamicscomingfromthemodelapproximation used for the secondary loop. Note that this kind of approximation is always needed if simple-model based tuning rules are to be applied. The rest of the paper is organized as follows. Next section presents the cascade control configuration and control setup to be used. Section 3 provides the main contribution of the paper as the design approach involving tuning of the controllers and approximation method. Section 4 presents an application example whereas section 5 ends with some conclusions and suggestions for further research.
TL;DR: An heuristic algorithm for redistributing the fragments in the nodes of a network is proposed, which minimizes the size of the data transferred for solving a request.
Abstract: A distributed system database performance is strongly related to the fragment allocation in the nodes of the network. An heuristic algorithm for redistributing the fragments is proposed. The algorithm uses the statistical information relative to the requests send to a distributed database. This algorithm minimizes the size of the data transferred for solving a request. Assuming that a distribution of the fragments in the nodes of a network is known, the algorithm generates a plan to transfer data fragments, plan that will be used to evaluate a request.
TL;DR: This paper aims at presenting the systems theory-based approach to the learning (instructional) process, based on the definition of an automatic regulation system and artificial intelligence techniques, which enables solving the problems of the complexity and uncertainty of the learning systems and, particularly, those of the e-learning.
Abstract: This paper aims at presenting the systems theory-based approach to the learning (instructional) process. Such as approach is necessary, if one takes into con- sideration the the complex and holistic nature of the learning process. The presented modeling is based on the definition of an automatic regulation system and artificial intelligence techniques. For this purpose, an Intelligent Instructional System (IIS) is defined using the concepts: inputs, outputs, perturbations factors, regulation, feed- back and AI learning techniques. The contextual environment of learning plays the major role in this system and it establishes the perturbation factors. The regulation consists in AI learning techniques, so the IIS is a flexible and adaptive system. The process' behaviour is described using pseudo-boolean and linear equations. This kind of approach enables solving the problems of the complexity and uncertainty of the learning (instructional) systems and, particularly, those of the e-learning (online and offline). Applications of the proposed approach may be found in e-learning courses
TL;DR: A new technique for robust MIMO controllers synthesis and reduction based on a reference model and moments approach intended to control a MIMo thermal system is presented.
Abstract: In this paper we present a new technique for robust MIMO controllers synthesis and reduction based on a reference model and moments approach intended to control a MIMO thermal system. The reference model allows to specify the performances requirements for the closed loop and improve the controller robustness while the moments tool (frequency and time ones) is used to reduce the controller structure using a Non Linear Optimization. The implementation on the real system associates this methodology of MIMO PID controllers synthesis with Broida’s identification technique in order to carry out a auto-tuning procedure [2][11].
TL;DR: The number of efficient points in criteria space of multiple objective combinatorial optimization problems is considered and it is concluded that under certain assumptions, that number grows polynomially although the number of Pareto optimal solutions grows exponentially with the problem size.
Abstract: The number of efficient points in criteria space of multiple objective combinatorial optimization problems is considered in this paper. It is concluded that under certain assumptions, that number grows polynomially although the number of Pareto optimal solutions grows exponentially with the problem size. In order to perform experiments, an original algorithm for obtaining all efficient points was formulated and implemented for three classical multiobjective combinatorial optimization problems. Experimental results with the shortest path problem, the Steiner tree problem on graphs and the traveling salesman problem show that the number of efficient points is much lower than a polynomial upper bound.