Custom Annotations: Handling Meta-Information in Modelica

Annotations and attributes form an important part of the Modelica language. They are used to include various meta-information such as documentation, external C-code, compilation hints, etc. Given the increasingly wide field of potential applications the set of useful annotations becomes too large to be included in the language specification. Hence we present a proposal how a Modelica modeler may define his own annotations and how such custom annotations can be organized within Modelica libraries. In the long term, the goal is to move the definition of standardized annotation, as well as of attributes, from the Modelica specification to a standard library

Experimental aspects of PIV applied to a Bo 105 helicopter in hover-flight condition.

PIV experiments have been performed in order to derive quantitative flow velocity data of the blade tip vortex of a helicopter at full-scale. Due to relatively rough outdoor conditions e.g. to the helicopter induced wind, the ambient light, the large observation distances and changing winds, the seeding illumination and recording of this type of flow was challenging. This paper describes technical aspects of the measurement and presents first results

Determinants of Small-Scale Farmers' Intention to Use Smartphones for Generating Agricultural Knowledge in Developing Countries: Evidence from Rural India

Access to and usage of smartphones for agricultural purposes amongst small-scale farmers in rural areas of developing countries is still limited. Smartphones may provide an opportunity to develop farmers' capacities with specific applications offering fast access to continually updated and reliable information. This study develops a framework to investigate the cognitive and affective behavioural drivers of smallholder farmers ' intention to use a smartphone in a developing country context. For this, survey data was collected from 664 randomly selected small-scale farmers in Bihar State, India in 2016. The analysis included a partial least square estimation of the behavioural model. The results confirm positive influences on the intention to use a smartphone for agricultural purposes through subjective norms, attitude, self-control, as well as positive and negative anticipated emotions. There is no evidence that negative anticipated emotions related to failure outweighed other factors. These results extend the academic literature with new conceptual insights and provide application-oriented implications for stakeholders, such as NGOs, extension services and research institutes

Real-Time Models for Wheels and Tyres in an Object-Oriented Modelling Framework

This article presents models for wheels and tyres in the application field of real-time multi-body systems. For this rather broad class of applications it is difficult to foresee the right level of model complexity that is affordable in a specific simulation. Therefore we developed a tyre model that is adjustable in its degree of complexity. It consists of a list of stepwise developed sub-models, each at a higher level of complexity. These models include semi-empirical equations. The stepwise development process is also reflected in the corresponding implementation with the modelling language Modelica. The final wheel model represents a supermodel and enables users to select the right level of complexity in an unambiguous way

Proceedings of the 9th International MODELICA Conference

The 9th International Modelica Conference is the main event for users, library developers, tool vendors and language designers to share their knowledge and learn about the latest scientific and industrial progress related to Modelica, to the Modelica Association and to the Functional Mockup Interface

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Nonlinear Observers based on the Functional Mockup Interface with Applications to Electric Vehicles

At DLR, an innovative electric vehicle is being developed that requires advanced, nonlinear control systems for proper functioning. One central aspect is the use of nonlinear observers for several modules. A generic concept was developed and implemented in a prototype to automatically generate a nonlinear observer model in Modelica, given a continous (usually nonlinear) Modelica model of the physical system to be observed. The approach is based on the Functional Mockup Interface (FMI), by exporting the model in FMI format and importing it agian in a form that enables the application of different observer designs, like EKF and UKF nonlinear Kalman Filters. The approach is demonstrated at hand of an observer for the nonlinear battery model of the electric vehicle of DLR

Thermodynamic Property and Fluid Modeling with Modern Programming Language Construct

Modelica is used extensively to model thermo-fluid pipe networks. Experience shows that Modelica models in this domain have limitations due to missing functional expressiveness of the Modelica language. In this paper, a prototype is described that demonstrates how thermodynamic property and thermo-fluid pipe component modeling could be considerably enhanced via modern language constructs. This prototype is based on the Modia modelling and simulation prototype and relies on features of the Julia programming language. It utilizes some key ideas of Modelica.Media, and part of Modelica.Media was semi-automatically translated to Julia

Kinetic separation of CO2/CH4 mixtures with Ni-MOF-74@Al2O3 core–shell composites

A novel core–shell species for the adsorption-based separation of carbon dioxide (CO2) from methane (CH4) is introduced by hydrothermal synthesis of Ni-MOF-74 on mesoporous spherical Al2O3 carrier substrate. The material was characterized and the shell thickness determined by means of optical and scanning electron microscopy as well as volumetric adsorption and fluid displacement experiments. Kinetic experiments with Ni-MOF-74@Al2O3 core–shell composites carried out at 303.15 K and at pressures up to 10 bar expose remarkably dominating uptake rates for CO2 over CH4. In the contrary Ni-MOF-74@Al2O3 appears to be unselective according to equilibrium data at the same conditions. Dynamic breakthrough experiments of binary CH4/CO2-mixtures (at 303.15 K and 5 bar) prove the prevailing effect of adsorption kinetics and the storage function of the mesoporous core. This statement is supported by a considerable boost in CO2-selectivity and capacity compared to adsorption equilibria measured on pure Ni-MOF-74 by the factor of 55.02 and up to 2.42, respectively