| 1. |
- Trydeman Knudsen, Marie, et al.
(författare)
-
Characterization factors for land use impacts on biodiversity in life cycle assessment based on direct measures of plant species richness in European farmland in the ‘Temperate Broadleaf and Mixed Forest`.
- 2017
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 580, s. 358-366
-
Tidskriftsartikel (refereegranskat)abstract
- Life Cycle Assessment (LCA) is a widely used tool to assess environmental sustainability of products. The LCAshould optimally cover themost important environmental impact categories such as climate change, eutrophicationand biodiversity. However, impacts on biodiversity are seldom included in LCAs due tomethodological limitationsand lack of appropriate characterization factors. When assessing organic agricultural products theomission of biodiversity in LCA is problematic, because organic systems are characterized by higher species richnessat field level compared to the conventional systems. Thus, there is a need for characterization factors to estimateland use impacts on biodiversity in life cycle assessment that are able to distinguish between organic andconventional agricultural land use that can be used to supplement and validate the few currently suggested characterization factors. Based on a unique dataset derived fromfield recording of plant species diversity in farmlandacross six European countries, the present study provides newmidpoint occupation Characterization Factors(CF) expressing the Potentially Disappeared Fraction (PDF) to estimate land use impacts on biodiversity in the‘Temperate Broadleaf and Mixed Forest’ biome in Europe. The method is based on calculation of plant specieson randomly selected test sites in the biome and enables the calculation of characterization factors that are sensitiveto particular types ofmanagement.While species richness differs between countries, the calculated CFs areable to distinguish between different land use types (pastures (monocotyledons or mixed), arable land andhedges) and management practices (organic or conventional production systems) across countries. The new occupationCFs can be used to supplement or validate the fewcurrent CF's and can be applied in LCAs of agriculturalproducts to assess land use impacts on species richness in the ‘Temperate Broadleaf and Mixed Forest’ biome.
|
|
| 2. |
- Kulcsár, Balázs Adam, 1975, et al.
(författare)
-
Unknown input reconstruction for LPV systems
- 2010
-
Ingår i: International Journal of Robust and Nonlinear Control. - 1099-1239 .- 1049-8923. ; 20:5, s. 579-595
-
Tidskriftsartikel (refereegranskat)abstract
- Detection and invariant subspaces of unknown inputs' signals for linear parameter-varying systems are examined in the paper. For a class of nonlinear system like this, the effect of unmeasured signals in parameter-varying measurement equation at the plant output is investigated.The main contributions of the paper are the parameter-varying extension of the pseudo-actuation of the possible and generic unknown sensor signal and the proposition of parameter-dependent similarity transformation. The general parameter-varying measurement equation is casted into a parameter-independent form by the similarity transformation, if any. Moreover, it showed that the nonlinear state transformation does not modify the output subspace spanned by the equivalent pseudo-actuator directions.
|
|
| 3. |
- Luspay, T., et al.
(författare)
-
Linear Parameter Varying Identification of Freeway Traffic Models
- 2011
-
Ingår i: IEEE Transactions on Control Systems Technology. - 1063-6536 .- 1558-0865. ; 19:1, s. 31-45
-
Tidskriftsartikel (refereegranskat)abstract
- This paper deals with linear parameter varying (LPV) modeling and identification of a generic, second-order freeway traffic flow model. A non-conventional technique is proposed to transform the nonlinear freeway traffic flow model into a parameter-dependent form. The resulting exact LPV model is equivalent to the original nonlinear dynamics. Simplification of the nonlinear model gives rise to the introduction of an approximate LPV description. The application of parameter varying identification approaches are made possible by the transformation. Closed-loop predictor-based subspace identification for LPV systems (PBSID LPV) is applied to estimate the affine parameter matrices of the LPV freeway models developed. If the model structure of the original plant is assumed to be known, this paper shows a solution how to estimate LPV model parameters based on the identified model. Parameter-dependent models are identified and validated using real detector measurement data in order to emphasize the applicability of the kernel PBSID LPV methodology. Comparison with traditional nonlinear parametric identification, generally used in traffic identification, is also provided.
|
|
| 4. |
- Bengmark, Samuel, 1965, et al.
(författare)
-
PREP- Pragmatic Research on Educational Practice
- 2023
-
Ingår i: SEFI 2023 - 51st Annual Conference of the European Society for Engineering Education : Engineering Education for Sustainability, Proceedings - Engineering Education for Sustainability, Proceedings. - : SEFI. - 9782873520267 ; , s. 163-172
-
Konferensbidrag (refereegranskat)abstract
- We investigate a concept called PREP - Pragmatic Research on Educational Practice, with the goal of engaging engineering educators in studying, documenting and sharing their initiatives to improve teaching practices. This concept is compared to other methodologies where the researcher and educational practitioner sometimes coincide. The study is based on a pilot, with six participants following the PREP program for three months, which we study autoethnographically. We also carried out a focus group discussion (n=12) to investigate to what extent university teachers regard the ideas from the PREP program as helpful for studying educational activities and sharing what they do and find.
|
|
| 5. |
- Dong, J, et al.
(författare)
-
Fault detection for LPV systems using model parameters that can be estimated via linear least squares
- 2014
-
Ingår i: International Journal of Robust and Nonlinear Control. - : Wiley. - 1099-1239 .- 1049-8923. ; 24:14, s. 1989-1999
-
Tidskriftsartikel (refereegranskat)abstract
- This paper presents a fault detection approach for discrete-time affine linear parameter varying systems with additive faults. A finite horizon input-output linear parameter varying model is used to obtain a linear in the model parameter regression residual form. The bias in the residual term vanishes because of quadratic stability of an underlying observer. The new methodology avoids projecting the residual onto a parity space, which in real time requires at least quadratic computational complexity. When neglecting the bias, the fault detection is carried out by an χ2 hypothesis test. Finally, the algorithm uses model parameters that can be identified prior to the on-line fault detection with linear least squares. A realtime experiment is carried out to demonstrate the viability of the proposed method.
|
|
| 6. |
- Kulcsár, Balázs Adam, 1975, et al.
(författare)
-
Impulse response parameter based internal model control for discrete-time LPV systems
- 2014
-
Ingår i: 13th European Control Conference, ECC 2014, Strasbourg Convention and Exhibition Center, Place de Bordeaux, Strasbourg, France, 24-27 June 2014. - 9783952426913 ; , s. 424-429
-
Konferensbidrag (refereegranskat)abstract
- This paper presents a novel impulse response parameter based solution for internal model control (IMC) within the linear parameter varying framework. First, based on a discrete-time state-space representation, a finite horizon vector autoregressive model with exogenous disturbance (VARX) is obtained to describe the I/O relationship of an affine LPV plant. In this paper, inversion of the VARX model w.r.t. control input directly leads to a IMC law where analytic solution can be derived for unconstrained and optimal reference tracking error minimization. When the bias term in the finite horizon I/O predictor is neglected, asymptotic properties of closed-loop IMC is analyzed. The VARX parameters of the I/O LPV model can be factorized into a scheduling dependent data matrix and a sequence of constant impulse response parameters (IRPs). The latter part can consistently be identified from data as a single least-squares problem. Without the need to build or identify an LPV state-space model, this methodology is able to address IMC tracking error minimization by using IRPs. The viability of the proposed method is numerically tested in simulation environment.
|
|
| 7. |
- Luspay, T., et al.
(författare)
-
Parameter-dependent modeling of freeway traffic flow
- 2010
-
Ingår i: Transportation Research, Part C: Emerging Technologies. - : Elsevier BV. - 0968-090X. ; 18:4, s. 471-488
-
Tidskriftsartikel (refereegranskat)abstract
- In the paper a novel non-linear modeling formalism is suggested for freeway traffic flow. A second-order macroscopic model has been transformed into a Linear Parameter Varying (LPV) model. The paper proposes two LPV descriptions for traffic modeling: the first one covers completely the non-linear macroscopic dynamics, while the second one is an approximate description. Real test field topology and measurement data are used for validating the proposed modeling methodology. Simulation examples are given to compare real detector measurements, non-linear and the parameter-dependent responses.
|
|
| 8. |
- Peni, T., et al.
(författare)
-
Induced L2 norm improvement by interpolating controllers for discrete time LPV systems
- 2009
-
Ingår i: European Journal of Control. - 0947-3580. ; 15:5, s. 1-15
-
Tidskriftsartikel (refereegranskat)abstract
- The paper shows an interpolation-based control solution asapossible technique to formulate the constrained H∞ control problem for discrete-time linear parameter varying (LPV) systems. The control policy is constructed by interpolating amongapriori designed, unconstrained, constant, state feedback controllers. Invariant set theory is used to introduce the measure of the domain of applicability. It is shown that the `trade-off' between the performance and the size of the domain of applicability can be significantly reduced by controller interpolation. Hence, the interpolation-based controller becomes applicable overamuch larger region than any other single state feedback. The proposed method gives stabilizing solution not only under hard constraints, but also allows the online modification of the induced L² norm from the generalized disturbance input to the predefined performance output. Moreover, the suggested method can be applied in real-time environment.
|
|
| 9. |
- Peni, T., et al.
(författare)
-
Model recovery anti-windup control for linear discrete time systems with magnitude and rate saturation
- 2012
-
Ingår i: American Control Conference. - : IEEE. - 0743-1619. - 9781457710957 ; , s. 1543-1548
-
Konferensbidrag (refereegranskat)abstract
- The paper proposes a model recovery anti-windup (MRAW) scheme for linear time-invariant and discrete-time systems under magnitude and rate saturation. The method is a modified, discrete-time counterpart of the algorithm presented in [4]. As it is usual in the MRAW framework the AW compensator contains the exact copy of the plant in order that the ideal (unsaturated) behavior can be preserved in the states. The compensator is a controller that aims to push the plant towards this intended behavior. The design of this control action can be reduced to a construction of a stabilizing state feedback acting on the saturated plant. In [4] this feedback is a linear one, which is designed by convex optimization by enlarging the ellipsoidal approximation of the invariant domain. This paper presents a different, set-theoretic approach, which is based on the precise construction of the maximal control invariant set. The proposed control is a nonlinear one generated by point wise convex optimization.
|
|
