| 1. |
- Jensen, Lars
(author)
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Digital reglering av klimatprocesser
- 1978
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Doctoral thesis (other academic/artistic)abstract
- Results from a research project supported by the Swedish Council for Building Research are reported. The main task was to improve climate control technology. The work was focused on digital control. It was split up into three main tasks: model building, design of regulators, and fullscale experiments. Several rooms, airducts, and heat exchangers were modelled. Simple dynamic models have been derived from mass and energy balance equations. The correspondance with experimental models is rather crude. The main problem is to choose certain heat transfer coefficients. Several control experiments showed that the PI-regulator gives a good result in many cases. Adjustment of regulator parameters can be very time consuming. In some cases a solution is to use a self-tuning regulator. A simple self-tuning regulator, called the quotient regulator, has been developed. The computer technology makes it possible to implement better control principles. The experiments show that there is room for improvements of climate control systems and that substantial energy savings can sometimes be obtained. An interpretative process control language suitable for climate control is also described.
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| 2. |
- Sundqvist, Bertil, et al.
(author)
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Low noise and drift by parallel amplifiers
- 1975
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In: Review of Scientific Instruments. - : American Institute of Physics. - 0034-6748 .- 1089-7623. ; 46:7, s. 928-929
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Journal article (peer-reviewed)abstract
- A low noise and low drift amplifier has been constructed using several monolithic operational amplifiers in parallel. It is shown that each amplifier may be connected by only three resistors. An input noise of 0.15 µV (p–p) in the band 0.1–10 Hz was obtained with six amplifiers, and the noise is expected to decrease as N−1/2 as the number of units is increased.
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| 6. |
- Schmidtbauer, Bengt
(author)
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High-accuracy sounding rocket attitude estimation using star sensor data
- 1978
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In: IEEE Transactions on Aerospace and Electronic Systems. - 0018-9251 .- 1557-9603. ; 14:6, s. 891-898
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Journal article (peer-reviewed)abstract
- A three-axis reconstitution scheme for spin stabilized sounding rockets is presented, using star transit pulse information from a single slit all solid state star sensor. The method, based on Kalman filtering and smoothing, gives accuracies in the arcminute range and has been successfully tested on four different missions in the Swedish sounding rocket program
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| 7. |
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| 8. |
- Hagander, Per, et al.
(author)
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Models for the Insulin Response to Intravenous Glucose
- 1978
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In: Mathematical Biosciences. - : Elsevier BV. - 0025-5564. ; 42, s. 15-29
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Journal article (peer-reviewed)abstract
- The Grodsky packet storage model describes many features of insulin release, but at present more or less arbitrary simplifications are necessary. The consequences of various simplifications are discussed, especially with regard to identification of parameters thought to be of importance for glucose tolerance. In particular, the insulin release dynamics of the ordinary intravenous glucose tolerance test is examined. The proposed model contains the following features: It considers arterial rather than venous blood glucose concentration as the stimulus, it takes the glucose injection time into account, and it contains a positive derivative term during the rise of the glucose concentration. When the insulin elimination-rate time constant is fixed to an a priori value, model fitting gives a clear quantification of the sensitivity of early and late insulin release to glucose.
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| 13. |
- Aly, Gharib, et al.
(author)
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Dynamical behavior of mixer settlers II: Models and identification
- 1972
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In: Journal of Applied Chemistry and Biotechnology. - : Wiley. - 0375-9210. ; 22:11, s. 1165-1184
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Journal article (peer-reviewed)abstract
- Mathematical models explaining the dynamics of the mixer-settler unit are investigated. It is shown that the static model is inadequate in this context and a two-part dynamic model is proposed.
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| 21. |
- Bellman, R., et al.
(author)
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On Structural Identifiability
- 1970
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In: Mathematical Biosciences. - 0025-5564. ; 7, s. 329-339
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Journal article (peer-reviewed)abstract
- In this article we introduce a new concept, structural identifiability, which plays a central role in identification problems. The concept is useful when answering questions such as: To what extent is it possible to get insight into the internal structure of a system from input-output measurements? What experiments are necessary in order to determine the internal couplings uniquely? The definition of the concept of an identifiable structure is given. Criteria as well as certain identifiable structures are discussed. Particular emphasis is given to compartmental models.
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| 22. |
- Bengtsson, Gunnar, et al.
(author)
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A design scheme for incomplete state or output feedback with applications to boiler and power system control
- 1974
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In: Automatica. - : Elsevier BV. - 0005-1098. ; 10:1, s. 15-30
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Journal article (peer-reviewed)abstract
- The problem of designing a linear feedback when all state variables are not available is discussed. The design scheme is based on computation of a complete state feedback and a reduction to a specified structure. The reduction is made by approximation of the eigenspace corresponding to a set of dominant eigenvalues. The method consists of successive choices of weightings on this space. The method is applied to the control of a boiler and a three-machine power system. In the power system case the complete state feedback can be replaced by local output feedback without significant decrease in performance.The examples indicate that the proposed method is a realistic design method for multivariable systems.
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| 23. |
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| 26. |
- Borisson, Ulf, et al.
(author)
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An Industrial Application of a Self-Tuning Regulator
- 1974
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In: 4th IFAC/IFIP International Conference on Digital Computer Applications to Process Control. - Berlin, Heidelberg : Springer Berlin Heidelberg. - 9783540066200 ; 93
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Conference paper (peer-reviewed)abstract
- An implementation of a self-tuning regulator is described. The regulator algorithm consists of two steps. Firstly the parameters of a model of the process are estimated in real time using the method of least squares. Secondly a minimum variance regulator based on the estimated parameters is computed at each sampling interval. Implementation of the algorithm on a process computer is discussed. Questions concerning program structure and storage requirements are considered. Results from the moisture content control on a paper machine are presented. The experiences are very good concerning the start-up behaviour as well as the stationary behaviour of the self-tuning regulator.
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| 27. |
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| 29. |
- Caines, Peter E., et al.
(author)
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Prediction Error Estimators : Asymptotic Normality and Accuracy
- 1976
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In: Proceedings of the 1976 IEEE Conference on Decision and Control including the 15th Symposium on Adaptive Processes. ; , s. 652-658
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Conference paper (peer-reviewed)abstract
- In this paper the asymptotic normality of a large class of prediction error estimators is established. (Prediction error identification methods were introduced in [1] and further developed in [2] and [3].) The observed processes in this paper are assumed to be stationary and ergodic and the parameterized process models are taken to be non-linear regression models. In the gaussian case the results presented in this paper constitute substantial generalizations of previous results concerning the asymptotic normality of maximum likelihood estimators for (i) processes of independent random variables [9,4] and (ii) Markov processes [5]; these results also generalize previous results on the asymptotic normality of least squares estimators for autoregressive moving average processes [6,7]. The asymptotic normality theorem gives formulae for the covariances of the asymptotic distributions of the parameter estimation errors arising from the specified class of prediction error identification methods. Employing these formulae it is demonstrated that the prediction error method using the determinant of the residual error covariance matrix as loss function is asymptotically efficient with respect to the specified class of prediction error estimators regardless of the distribution of the observed processes.
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| 30. |
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| 33. |
- Friedlander, B, et al.
(author)
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Extended Levinson and Chandrasekhar Equations for General Discrete-Time Linear Estimation Problems
- 1978
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In: IEEE Transactions on Automatic Control. - : IEEE Control Systems Society. - 0018-9286 .- 1558-2523. ; 23:4, s. 653-659
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Journal article (peer-reviewed)abstract
- Recursive algorithrms for the solution of linear least-squares estimation problems have been based mainly on state-space models. It has been known, however, that recursive Levinson-Whittle-Wiggins-Robinson (LWR) algorithms exist for stationary time-series, using only input-output information (i.e, covariance matrices). By introducing a way of classifying stochastic processes in terms of an "index of nonstationarity" we derive extended LWR algorithms for nonstationary processes We show also how adding state-space structure to the covariance matrix allows us to specialize these general results to state-space type estimation algorithms. In particular, the Chandrasekhar equations are shown to be natural descendants of the extended LWR algorithm.
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| 34. |
- Friedlander, B, et al.
(author)
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Levinson and Chandrasekhar-Type Equations for a General Discrete-Time Linear Estimation Problem
- 1976
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In: Proceedings of the 1976 IEEE Conference on Decision and Control including the 15th Symposium on Adaptive Processes. ; , s. 910-915
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Conference paper (peer-reviewed)abstract
- Recursive algorithms for the solution of linear least-squares estimation problems have been based mainly on state-space models. It has been know, however, that such algorithms exist for stationary time-series, using input-output descriptions (e.g., covariance matrices). We introduce a way of classifying stochastic processes in terms of their "distance" from stationarity that leads to a derivation of an efficient Levinson-type algorithm for arbitrary (nonstationary) processes. By adding structure to the covariance matrix, these general results specialize to state-space type estimation algorithms. In particular, the Chandrasekhar equations are shown to be the natural descendants of the Levinson algorithm.
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| 35. |
- Friedlander, Benjaming, et al.
(author)
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New Inversion Formulas for Matrices Classified in Terms of their Distance from Toeplitz Matrices
- 1979
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In: Linear Algebra and its Applications. - : Elsevier. - 0024-3795 .- 1873-1856. ; 27, s. 31-60
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Journal article (peer-reviewed)abstract
- The problem of solving linear equations, or equivalently of inverting matrices, arises in many fields. Efficient recursive algorithms for finding the inverses of Toeplitz or displacement-type matrices have been known for some time. By introducting a way of characterizing matrices in terms of their “distance” from being Toeplitz, a natural extension of these algorithms is obtained. Several new inversion formulas for the representation of the inverse of non-Toeplitz matrices are also presented.
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| 36. |
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| 37. |
- Gillblad, Tomas, et al.
(author)
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Implementation Problems for Activated Sludge Controllers
- 1978
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Reports (other academic/artistic)abstract
- The paper describes some problems that appear in the implementation of a computer control system in a wastewater treatment plant. The problems are related to the control authority of the actuators, the influence of the process design on the controller design, or the disturbance pattern. Some experience from two full scale activated sludge plants in Sweden are discussed.
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| 38. |
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| 39. |
- Glad, Torkel, 1947-, et al.
(author)
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A Multiplier Method with Automatic Limitation of Penalty Growth
- 1979
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In: Mathematical programming. - : Springer. - 0025-5610 .- 1436-4646. ; 17:1, s. 140-155
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Journal article (peer-reviewed)abstract
- This paper presents a multiplier method for solving optimization problems with equality and inequality constraints. The method realizes all the good features that were foreseen by R. Fletcher for this type of algorithm in the past, but which suffers from none of the drawbacks of the earlier attempts.
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| 40. |
- Glad, Torkel, 1947-, et al.
(author)
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Optimization of Functions whose Values are Subject to Small Errors
- 1977
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In: BIT Numerical Mathematics. - : Kluwer Academic Publishers. - 0006-3835 .- 1572-9125. ; 17:2, s. 160-169
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Journal article (peer-reviewed)abstract
- In this paper we consider the minimization of a function whose values can only be obtained with an error. For the case when the error has certain statistical properties this problem has been investigated by Kiefer and Wolfowitz (1) and Kushner (2, 3). Kushner has shown that a certain class of algorithms converge to a stationary point with probability one. Here a different approach is used. The error is assumed to have an upper bound and it is shown that a stationary point can be obtained to within a certain accuracy, dependent on the magnitude of the error. Our results are related to works concerning roundoff errors for one dimensional optimization (4) and solution of nonlinear equations (5). The algorithm we use can be regarded as an extension of the methods used in (6), (8) and (9).
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| 41. |
- Glad, Torkel, 1947-
(author)
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Properties of Updating Methods for the Multipliers in Augmented Lagrangians
- 1979
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In: Journal of Optimization Theory and Applications. - : Kluwer Academic Publishers. - 0022-3239 .- 1573-2878. ; 28:2, s. 135-156
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Journal article (peer-reviewed)abstract
- The convergence properties of different updating methods for the multipliers in augmented Lagrangians are considered. It is assumed that the updating of the multipliers takes place after each line search of a quasi-Newton method. Two of the updating methods are shown to be linearly convergent locally, while a third method has superlinear convergence locally. Modifications of the algorithms to ensure global convergence are considered. The results of a computational comparison with other methods are presented.
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| 42. |
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| 43. |
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| 45. |
- Gustavsson, Ivar, et al.
(author)
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Identification of Processes in Closed Loop-Identifiability and Accuracy Aspects
- 1977
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In: Automatica. - : Elsevier. - 0005-1098 .- 1873-2836. ; 13, s. 59-75
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Journal article (peer-reviewed)abstract
- It is often necessary in practice to perform identification experiments on systems operating in closed loop. There has been some confusion about the possibilities of successful identification in such cases, evidently due to the fact that certain common methods then fail. A rapidly increasing literature on the problem is briefly surveyed in this paper, and an overview of a particular approach is given. It is shown that prediction error identification methods, applied in a direct fashion will given correct estimates in a number of feedback cases. Furthermore, the accuracy is not necessarily worse in the presence of feedback; in fact optimal inputs may very well require feedback terms. Some practical applications are also described.
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| 46. |
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| 47. |
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| 48. |
- Hagander, Per, et al.
(author)
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A Self-Tuning Filter for Fixed-Lag Smoothing
- 1976
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Conference paper (peer-reviewed)abstract
- The problem of estimating a discrete-time stochastic signal which is corrupted by additive white measurement noise is discussed. How the stationary solution to the fixed-lag smoothing problem can be obtained is shown. The first step is to construct an innovation model for the process. It is then shown how the fixed-lag smoother can be determined from the polynomials in the transfer function of the innovation model. In many applications, the signal model and the characteristics of the noise process are unknown. It is shown that it is possible to derive an algorithm which on-line finds the optimal fixed-lag smoother, a self-tuning smoother. The self-tuning smoother consists of two parts: an on-line estimation of the parameters in the one-step ahead predictor of the measured signal, and a computation of the smoother coefficients by simple manipulation of the predictor parameters. The smoother has good transient, as well as good asymptotic, properties.
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| 49. |
- Hagander, Per, et al.
(author)
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A Self-Tuning Filter for Fixed-Lag Smoothing
- 1977
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In: IEEE Transactions on Information Theory. - 0018-9448. ; 23:3, s. 377-384
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Journal article (peer-reviewed)abstract
- The problem of estimating a discrete-time stochastic signal which is corrupted by additive white measurement noise is discussed. How the stationary solution to the fixed-lag smoothing problem can be obtained is shown. The first step is to construct an innovation model for the process. It is then shown how the fixed-lag smoother can be determined from the polynomials in the transfer function of the innovation model. In many applications, the signal model and the characteristics of the noise process are unknown. It is shown that it is possible to derive an algorithm which on-line finds the optimal fixed-lag smoother, a self-tuning smoother. The self-tuning smoother consists of two parts: an on-line estimation of the parameters in the one-step ahead predictor of the measured signal, and a computation of the smoother coefficients by simple manipulation of the predictor parameters. The smoother has good transient, as well as good asymptotic, properties.
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| 50. |
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