The authors study the performance of feedforward artificial neural networks in forecasting future... more The authors study the performance of feedforward artificial neural networks in forecasting future values of several different time series. They explore both short- and long-term prediction of several periodic time series. They find that a significant source of error in long-term prediction of time series is introduced by a phase shift between the network output and the time series. They explore the origin of this phase shift and suggest strategies for minimizing its effect. They find that the phase diagrams of the time series and the neural network forecast contain useful diagnostic information.
Journal of The Franklin Institute-engineering and Applied Mathematics, 1974
T?w d@culties in solving Fredholm integral equations of the first kind are well bnown. A classica... more T?w d@culties in solving Fredholm integral equations of the first kind are well bnown. A classical method has been to convert the equation into a set of m linear algebraic equation8 in n unknown8 (rng n). For computational convenience, it is customary to force m = n and solve the resulting ill-conditioned system using one technique or other. In the general ca8e, a feasible solution, if it exists, can be fou??d by determining the generalized inverse of the coeficient matrix. One method of @ding the generalized inverse is to reformulate the problem and observe the steady state response of a system of ordinary differential equations with prescribed initial conditions. ReSult8 obtained from this reform&&on are found to be comparable in quality to those obtained earlier by other methods. Analog and digital computer implementations a.re discussed.
International Journal of Systems Science, Apr 1, 1979
This paper investigates the advantages of combining the sensitivity analysis method of parameter ... more This paper investigates the advantages of combining the sensitivity analysis method of parameter estimation with a new computational method for the solution of systems of ordinary differential equations. It is shown that the new method allows one to take advantage of the fact that the sensitivity equations have the same structure as the model equations.
The purpose of this paper is to point out the need for performance evaluation measures and techni... more The purpose of this paper is to point out the need for performance evaluation measures and techniques suitable for the evaluation of specialized architectural features in nonnumeric applications. Toward this end, problems associated with the use of data base machines are examined at three levels of detail: the user level, the system level and the device level.
The International Conference on Artificial Neural Networks (ICANN) is the annual gathering organi... more The International Conference on Artificial Neural Networks (ICANN) is the annual gathering organized by the European Neural Network Society (ENNS) for neural network researchers, both European and non-European. The ENNS was established in Helsinki in June 1991, when the first ICANN was held under the direction of Teuvo Kohonen, one of the earliest pioneers of neural networks in Europe. The ENNS has steadily grown ever since, establishing along the way links with its sister societies: INNS and JNNS, the Internaitorial ...
This chapter discusses the language of system theory. The concept of āsystemā is as old as civili... more This chapter discusses the language of system theory. The concept of āsystemā is as old as civilization. A system is a collection of the objects that are united by some form of interaction or interdependence. A system might be regarded as a set of interrelated elements. The nature of elements that are involved and the relations that might exist among the elements depend upon the type of system under consideration. The fact that a system can be regarded as a set is useful because this allows one to draw freely from the edifice of knowledge that is available in set theory, topology, and function theory. The concept of a system can be traced back to antiquity; the āsystems approachā concept appears to be of a recent origin. The phrase āsystems approachā is associated with a cadre of disciplines that have arisen since World War II, the most familiar being operations research, management science, and systems analysis.
Many problems of contemporary interest are characterized by Fredholm type integral equations of t... more Many problems of contemporary interest are characterized by Fredholm type integral equations of the first kind. These equations are inherently ill-posed and difficult to solve. It is customary to convert the equation into a set of m algebraic equations Af = g in n unknowns with rn not necessarily equal to n. Then one can solve these m equations in a least square sense. Among the class of vectors f that minimize the Euclidean norm of the error, there exists a unique vector A+g which is of least norm where A + is the generalized inverse of A. One method of finding the generalized inverse of A is to reformulate the problem into an equivalent system of first order ordinary differential equations with specified initial conditions. The steady state solution of this system is A +g, the required value off. This procedure was implemented on an analog computer and the results presented.
A discretized version of Fredholm integral equation of the first kind is solved using an interval... more A discretized version of Fredholm integral equation of the first kind is solved using an interval programming algorithm and the results are compared with an initial value method.
A tutorial introduction to genetic algorithms is given. This brief tutorial should serve the purp... more A tutorial introduction to genetic algorithms is given. This brief tutorial should serve the purpose of introducing the subject to the novice. The tutorial is followed by a brief commentary on the term project reports that follow.
Traffic grooming is the term used to describe how different traffic streams are packed into highe... more Traffic grooming is the term used to describe how different traffic streams are packed into higher-speed streams. In a WDM SONET/ring network, each wavelength can carry several lower-rate traffic streams in TDM fashion. The traffic demand, which is an integer multiple of the timeslot capacity, between any two nodes is established on several TDM virtual connections. A virtual connection needs to be added and dropped only at the two end nodes of the connection; as a result, the electronic Add/Drop Multiplexors (ADMs) at intermediate nodes (if there are any) will electronically bypass this timeslot. Instead of having an ADM on every wavelength at every node, it may be possible to have some nodes on some wavelength where no add/drop is needed on any time slot; thus, the total number of ADMs in the networks (and hence the network cost) can be reduced. Under the static traffic pattern, the savings can be maximized by carefully packing the virtual connections into wavelengths. In this work, we allow arbitrary (non-uniform) traffic and we first present a formal mathematical definition of the problem, which turns out to be an integer linear program (ILP). Then, we propose a simulated-annealing-based heuristic algorithm for the case where all the traffic are carried on directly connected virtual connections (referred to as the "single-hop" case). Then, we study the case where a hub node is used to bridge traffic from different wavelengths (referred to as the multihop case). We find the following main results. The simulated-annealing-based approach has been found to achieve the best results so far in most cases relative to other comparable approaches proposed in the literature. In general, a multihop approach can achieve better equipment savings when the grooming ratio is large, but it consumes more bandwidth.
Traffic grooming is the term used to describe how different traffic streams are packed into highe... more Traffic grooming is the term used to describe how different traffic streams are packed into higher-speed streams. In a WDM SONET/ring network, each wavelength can carry several lower-rate traffic streams in TDM fashion. The traffic demand, which is an integer multiple of the timeslot capacity, between any two nodes is established on several TDM virtual connections. A virtual connection needs to be added and dropped only at the two end nodes of the connection; as a result, the electronic Add/Drop Multiplexors (ADMs) at intermediate nodes (if there are any) will electronically bypass this timeslot. Instead of having an ADM on every wavelength at every node, it may be possible to have some nodes on some wavelength where no add/drop is needed on any time slot; thus, the total number of ADMs in the networks (and hence the network cost) can be reduced. Under the static traffic pattern, the savings can be maximized by carefully packing the virtual connections into wavelengths. In this work, we allow arbitrary (non-uniform) traffic and we first present a formal mathematical definition of the problem, which turns out to be an integer linear program (ILP). Then, we propose a simulated-annealing-based heuristic algorithm for the case where all the traffic are carried on directly connected virtual connections (referred to as the "single-hop" case). Then, we study the case where a hub node is used to bridge traffic from different wavelengths (referred to as the multihop case). We find the following main results. The simulated-annealing-based approach has been found to achieve the best results so far in most cases relative to other comparable approaches proposed in the literature. In general, a multihop approach can achieve better equipment savings when the grooming ratio is large, but it consumes more bandwidth.
The purpose of this paper is to point out the need for performance evaluation measures and techni... more The purpose of this paper is to point out the need for performance evaluation measures and techniques suitable for the evaluation of specialized architectural features in nonnumeric applications. Toward this end, problems associated with the use of data base machines are examined at three levels of detail: the user level, the system level and the device level.
The authors study the performance of feedforward artificial neural networks in forecasting future... more The authors study the performance of feedforward artificial neural networks in forecasting future values of several different time series. They explore both short- and long-term prediction of several periodic time series. They find that a significant source of error in long-term prediction of time series is introduced by a phase shift between the network output and the time series. They explore the origin of this phase shift and suggest strategies for minimizing its effect. They find that the phase diagrams of the time series and the neural network forecast contain useful diagnostic information.
Journal of The Franklin Institute-engineering and Applied Mathematics, 1974
T?w d@culties in solving Fredholm integral equations of the first kind are well bnown. A classica... more T?w d@culties in solving Fredholm integral equations of the first kind are well bnown. A classical method has been to convert the equation into a set of m linear algebraic equation8 in n unknown8 (rng n). For computational convenience, it is customary to force m = n and solve the resulting ill-conditioned system using one technique or other. In the general ca8e, a feasible solution, if it exists, can be fou??d by determining the generalized inverse of the coeficient matrix. One method of @ding the generalized inverse is to reformulate the problem and observe the steady state response of a system of ordinary differential equations with prescribed initial conditions. ReSult8 obtained from this reform&&on are found to be comparable in quality to those obtained earlier by other methods. Analog and digital computer implementations a.re discussed.
International Journal of Systems Science, Apr 1, 1979
This paper investigates the advantages of combining the sensitivity analysis method of parameter ... more This paper investigates the advantages of combining the sensitivity analysis method of parameter estimation with a new computational method for the solution of systems of ordinary differential equations. It is shown that the new method allows one to take advantage of the fact that the sensitivity equations have the same structure as the model equations.
The purpose of this paper is to point out the need for performance evaluation measures and techni... more The purpose of this paper is to point out the need for performance evaluation measures and techniques suitable for the evaluation of specialized architectural features in nonnumeric applications. Toward this end, problems associated with the use of data base machines are examined at three levels of detail: the user level, the system level and the device level.
The International Conference on Artificial Neural Networks (ICANN) is the annual gathering organi... more The International Conference on Artificial Neural Networks (ICANN) is the annual gathering organized by the European Neural Network Society (ENNS) for neural network researchers, both European and non-European. The ENNS was established in Helsinki in June 1991, when the first ICANN was held under the direction of Teuvo Kohonen, one of the earliest pioneers of neural networks in Europe. The ENNS has steadily grown ever since, establishing along the way links with its sister societies: INNS and JNNS, the Internaitorial ...
This chapter discusses the language of system theory. The concept of āsystemā is as old as civili... more This chapter discusses the language of system theory. The concept of āsystemā is as old as civilization. A system is a collection of the objects that are united by some form of interaction or interdependence. A system might be regarded as a set of interrelated elements. The nature of elements that are involved and the relations that might exist among the elements depend upon the type of system under consideration. The fact that a system can be regarded as a set is useful because this allows one to draw freely from the edifice of knowledge that is available in set theory, topology, and function theory. The concept of a system can be traced back to antiquity; the āsystems approachā concept appears to be of a recent origin. The phrase āsystems approachā is associated with a cadre of disciplines that have arisen since World War II, the most familiar being operations research, management science, and systems analysis.
Many problems of contemporary interest are characterized by Fredholm type integral equations of t... more Many problems of contemporary interest are characterized by Fredholm type integral equations of the first kind. These equations are inherently ill-posed and difficult to solve. It is customary to convert the equation into a set of m algebraic equations Af = g in n unknowns with rn not necessarily equal to n. Then one can solve these m equations in a least square sense. Among the class of vectors f that minimize the Euclidean norm of the error, there exists a unique vector A+g which is of least norm where A + is the generalized inverse of A. One method of finding the generalized inverse of A is to reformulate the problem into an equivalent system of first order ordinary differential equations with specified initial conditions. The steady state solution of this system is A +g, the required value off. This procedure was implemented on an analog computer and the results presented.
A discretized version of Fredholm integral equation of the first kind is solved using an interval... more A discretized version of Fredholm integral equation of the first kind is solved using an interval programming algorithm and the results are compared with an initial value method.
A tutorial introduction to genetic algorithms is given. This brief tutorial should serve the purp... more A tutorial introduction to genetic algorithms is given. This brief tutorial should serve the purpose of introducing the subject to the novice. The tutorial is followed by a brief commentary on the term project reports that follow.
Traffic grooming is the term used to describe how different traffic streams are packed into highe... more Traffic grooming is the term used to describe how different traffic streams are packed into higher-speed streams. In a WDM SONET/ring network, each wavelength can carry several lower-rate traffic streams in TDM fashion. The traffic demand, which is an integer multiple of the timeslot capacity, between any two nodes is established on several TDM virtual connections. A virtual connection needs to be added and dropped only at the two end nodes of the connection; as a result, the electronic Add/Drop Multiplexors (ADMs) at intermediate nodes (if there are any) will electronically bypass this timeslot. Instead of having an ADM on every wavelength at every node, it may be possible to have some nodes on some wavelength where no add/drop is needed on any time slot; thus, the total number of ADMs in the networks (and hence the network cost) can be reduced. Under the static traffic pattern, the savings can be maximized by carefully packing the virtual connections into wavelengths. In this work, we allow arbitrary (non-uniform) traffic and we first present a formal mathematical definition of the problem, which turns out to be an integer linear program (ILP). Then, we propose a simulated-annealing-based heuristic algorithm for the case where all the traffic are carried on directly connected virtual connections (referred to as the "single-hop" case). Then, we study the case where a hub node is used to bridge traffic from different wavelengths (referred to as the multihop case). We find the following main results. The simulated-annealing-based approach has been found to achieve the best results so far in most cases relative to other comparable approaches proposed in the literature. In general, a multihop approach can achieve better equipment savings when the grooming ratio is large, but it consumes more bandwidth.
Traffic grooming is the term used to describe how different traffic streams are packed into highe... more Traffic grooming is the term used to describe how different traffic streams are packed into higher-speed streams. In a WDM SONET/ring network, each wavelength can carry several lower-rate traffic streams in TDM fashion. The traffic demand, which is an integer multiple of the timeslot capacity, between any two nodes is established on several TDM virtual connections. A virtual connection needs to be added and dropped only at the two end nodes of the connection; as a result, the electronic Add/Drop Multiplexors (ADMs) at intermediate nodes (if there are any) will electronically bypass this timeslot. Instead of having an ADM on every wavelength at every node, it may be possible to have some nodes on some wavelength where no add/drop is needed on any time slot; thus, the total number of ADMs in the networks (and hence the network cost) can be reduced. Under the static traffic pattern, the savings can be maximized by carefully packing the virtual connections into wavelengths. In this work, we allow arbitrary (non-uniform) traffic and we first present a formal mathematical definition of the problem, which turns out to be an integer linear program (ILP). Then, we propose a simulated-annealing-based heuristic algorithm for the case where all the traffic are carried on directly connected virtual connections (referred to as the "single-hop" case). Then, we study the case where a hub node is used to bridge traffic from different wavelengths (referred to as the multihop case). We find the following main results. The simulated-annealing-based approach has been found to achieve the best results so far in most cases relative to other comparable approaches proposed in the literature. In general, a multihop approach can achieve better equipment savings when the grooming ratio is large, but it consumes more bandwidth.
The purpose of this paper is to point out the need for performance evaluation measures and techni... more The purpose of this paper is to point out the need for performance evaluation measures and techniques suitable for the evaluation of specialized architectural features in nonnumeric applications. Toward this end, problems associated with the use of data base machines are examined at three levels of detail: the user level, the system level and the device level.
Uploads
Papers by Rao Vemuri