Personal Career Development Plans for all ESRs : Deliverable number: D1.1 - Version 1.1

In the ROMSOC project continuous career development strategies for the Early Stage Researchers (ESRs) are set up in order to enhance the career perspectives and employability of the recruited fellows to many public and private sectors (involving industry and research institutes). An intensive and highly qualified supervision and mentoring program, as well as the network-wide training activities contribute to the development of task-oriented research skills, generic research skills and transferable skills. The goal of the ROMSOC project is that the ESRs experience a wide range of interdisciplinary and intersectoral training to enable them to become professional workers and to take responsibility for their project and career management, while reflecting on their own skills and actively pursuing their own training needs.EC/H2020/765374/EU/Reduced Order Modelling, Simulation and Optimization of Coupled Systems/ROMSO

Self-adjoint differential-algebraic equations

Motivated from linear-quadratic optimal control problems for differential-algebraic equations (DAEs), we study the functional analytic properties of the operator associated with the necessary optimality boundary value problem and show that it is associated with a self-conjugate operator and a self-adjoint pair of matrix functions. We then study general self-adjoint pairs of matrix valued functions and derive condensed forms under orthogonal congruence transformations that preserve the self-adjointness. We analyze the relationship between self-adjoint DAEs and Hamiltonian systems with symplectic flows. We also show how to extract self-adjoint and Hamiltonian reduced systems from derivative arrays

The Signature Method for DAEs arising in the Modeling of Electrical Circuits

We consider the Signature Method for the structural analysis of differential-algebraic equations (DAEs) that arise in the modeling and simulation of electrical circuits. Different formulations of the set of model equations are considered. For some formulations we show that the structural approach may fail for certain circuit topologies, while other formulations are better suited for a structural analysis. The results are illustrated by a number of examples

Condensed Forms for linear Port-Hamiltonian Descriptor Systems

Motivated by the structure which arises in the port-Hamiltonian formulation of constraint dynamical systems, we derive structure preserving condensed forms for skew-adjoint differential-algebraic equations (DAEs). Moreover, structure preserving condensed forms under constant rank assumptions for linear port-Hamiltonian differential-algebraic equations are developed. These condensed forms allow us to further analyze the properties of port-Hamiltonian DAEs and to study e.g. existence and uniqueness of solutions. As examples the equations of motion of linear multibody systems and of linear electrical circuit equations are considered

A Combined Structural-Algebraic Approach for the Regularization of Coupled Systems of DAEs

The automated modeling of multi-physical dynamical systems is usually realized by coupling different subsystems together via certain interface or coupling conditions. This approach results in large-scale high-index differential-algebraic equations (DAEs). Since the direct numerical simulation of these kind of systems leads to instabilities and possibly non-convergence of the numerical methods a regularization or remodeling of the system is required. In many simulation environments a kind of structural analysis based on the sparsity pattern of the system is used to determine the index and a reduced system model. However, this approach is not reliable for certain problem classes, in particular we show that it is not suited for coupled systems of DAEs. We will present a new approach for the regularization of coupled dynamical systems that combines the structural analysis, in particular the Signature Method of Pryce, with classical algebraic regularization techniques and thus allows to handle so-called structurally singular systems and also enables a proper treatment of redundancies or inconsistencies in the system

Self-conjugate differential and difference operators arising in the optimal control of descriptor systems

We analyze the structure of the linear differential and difference operators associated with the necessary optimality conditions of optimal control problems for descriptor systems in continuous- and discrete-time. It has previously been shown that in continuous-time the associated optimality system is a self-conjugate operator associated with a self-adjoint pair of coefficient matrices and we show that the same is true in the discrete-time setting. We also extend these results to the case of higher order systems. Finally, we discuss how to turn higher order systems with this structure into first order systems with the same structure

Model Reduction for Kinetic Models of Biological Systems

High dimensionality continues to be a challenge in computational systems biology. The kinetic models of many phenomena of interest are high-dimensional and complex, resulting in large computational effort in the simulation. Model order reduction (MOR) is a mathematical technique that is used to reduce the computational complexity of high-dimensional systems by approximation with lower dimensional systems, while retaining the important information and properties of the full order system. Proper orthogonal decomposition (POD) is a method based on Galerkin projection that can be used for reducing the model order. POD is considered an optimal linear approach since it obtains the minimum squared distance between the original model and its reduced representation. However, POD may represent a restriction for nonlinear systems. By applying the POD method for nonlinear systems, the complexity to solve the nonlinear term still remains that of the full order model. To overcome the complexity for nonlinear terms in the dynamical system, an approach called the discrete empirical interpolation method (DEIM) can be used. In this paper, we discuss model reduction by POD and DEIM to reduce the order of kinetic models of biological systems and illustrate the approaches on some examples. Additional computational costs for setting up the reduced order system pay off for large-scale systems. In general, a reduced model should not be expected to yield good approximations if different initial conditions are used from that used to produce the reduced order model. We used the POD method of a kinetic model with different initial conditions to compute the reduced model. This reduced order model is able to predict the full order model for a variety of different initial conditions.TU Berlin, Open-Access-Mittel – 2020EC/H2020/765374/EU/Reduced Order Modelling, Simulation and Optimization of Coupled systems/ROMSO

Sex and body region effects on bone mineralization in male pigs

Lameness in pigs is one of the major reasons for culling and early losses in pigs. This can be linked to osteoporosis due to pathologic alterations in bone mineral density (BMD) or bone mineral content (BMC) and may also be linked to the sex. Dealing with the ban on piglet castration without anaesthesia in Germany 2021, we have three male "sex" types: entire boars (EB), immunocastrated boars (IB), and surgically castrated boars (SB). The hypothesis of the present study is that BMC or BMD varies between different male sex types. If sex has an effect on bone mineralization (BMC or BMD) and if this affects leg health, it could result in more lameness and problems during fattening in the negatively affected sex type. The present study evaluated bone mineralization (in terms of BMD and BMC) and body composition traits using dual-energy X-ray absorptiometry (DXA) three times during growth at 30, 50, and 90 kg live body weight. Nine body regions were analysed for bone mineral traits and compared for different male sex types and the fattening season. Significant differences were found regarding BMD (and BMC) among EB, IB, and SB for whole-body BMD (BMC). Additionally significant differences were found in the front and lower hind limbs, where SB showed a significantly higher BMD compared to EB, with IB in between. Additionally regional differences were detected among the groups. Further studies are needed to evaluate the effect of these differences in bone mineralization on leg health

Self-adjoint differential-algebraic equations

Motivated from linear-quadratic optimal control problems for differential-algebraic equations (DAEs), we study the functional analytic properties of the operator associated with the necessary optimality boundary value problem and show that it is associated with a self-conjugate operator and a self-adjoint pair of matrix functions. We then study general self-adjoint pairs of matrix valued functions and derive condensed forms under orthogonal congruence transformations that preserve the self-adjointness. We analyze the relationship between self-adjoint DAEs and Hamiltonian systems with symplectic flows. We also show how to extract self-adjoint and Hamiltonian reduced systems from derivative arrays

The influence of individual and cultural factors on perceptions of alcohol control strategies among university students in Europe

Alcohol control strategies vary between countries and reflect differences in drinking cultures. This study explored how perceived effectiveness of alcohol control strategies varies according to individual characteristics and country of residence. A cross-sectional online survey was completed by 1910 university students in Denmark, England, Germany, Italy, Portugal, and Switzerland. It assessed the perceived effectiveness of 11 alcohol control strategies. Correlates included sensation-seeking, alcohol outcome expectancies, drink refusal self-efficacy, and Alcohol Use Disorders Identification Test (AUDIT) scores. Bivariate analysis using mixed-measures MANOVA and Pearson correlations were followed by linear regression to identify multivariate correlates. These analyses revealed that educational strategies (e.g. teaching people skills to resist peer pressure) were considered more effective than restrictive strategies (e.g. raising the legal drinking age). Perceived effectiveness was greater among women and lighter drinkers. Country of residence also explained unique variance. The findings highlight the need to consider the potential impact of drinking culture in alcohol-related harm-reduction strategies