Dynamic reconfigurability is receiving more and more attention from both academy and industry, which means the ability to flexibly modify system functions by adding/removing hardware/software components, modifying logic relation between components, or updating particular system data at runtime without sacrificing the system performance. A distributed reconfigurable discrete event control system (DRDECS) is composed of several networked reconfigurable subsystems. In order to realize system functions, these reconfigurable subsystems communicate and coordinate with each other, since any casually reconfiguration applied to a subsystem may cause risks to others, or even to the safety of the whole system. This brief proposes a new coordination method for a DRDECS, where each subsystem is modeled by a reconfigurable timed net condition/event system. A virtual coordinator together with a communication protocol between it and subsystems is developed in order to achieve two aims: 1) to coordinate subsystems with an optimal coordination solution using judgement matrices while multiple subsystems require global reconfigurations and 2) to reduce exchanged messages between the coordinator and these subsystems. Furthermore, for the purpose of checking functional and temporal properties of a DRDECS with this virtual coordinator, a computation tree logic-based model checking method is applied. Finally, a hypothetic manufacturing plant is used as a running example to illustrate this brief.

Thermoelectric (TE) devices are used in the form of Peltier coolers and as TE generators, with the latter producing electrical energy from waste heat, based on the Seebeck effect. In both cases, modeling of the TE device is a prerequisite for the design and control verification of the resulting overall energy system. To this end, the model has to be integrated seamlessly in an overall system model containing other electrical, thermodynamic, or even mechanical components. Following this premise, this paper presents a component-based model for TE devices described in the Modelica language. The model incorporates the temperature dependences of decisive material properties (Seebeck coefficient, thermal conductivity, and electrical resistivity) in 1-D spatial resolution. With the help of few additional geometrical parameters, e.g., the thickness of TE legs, the model is capable of describing the dynamic behavior of the TE device in accordance with the experimental results.

Signal interpreted Petri nets (SIPN) show good properties in modeling and analyzing control algorithms. With SIPN, logic controllers are modeled by places-setting output signals-and transitions between those places-depending on Boolean functions of input signals. This model has interesting dynamics: Firstly, several transitions can fire simultaneously. Secondly, there can be iterated firing of transitions before a new stable marking is reached. In standard PLC programming languages, there is no direct means to implement these dynamics. In this contribution a method for the generation of transparent PLC code from SIPN is presented (using instruction list or ladder diagram). The code is transparent because there is a one-to-one correspondence between SIPN elements and code segments. A new analytical method to guarantee the correct dynamics of the implemented code is presented and compared to existing approaches. The new method results in a special ordering of the code segments. The presented analysis of the SIPN shows if a transition t/sub a/ can fire in an iteration after transition t/sub b/. In this case, the code segment describing t/sub b/ has to be processed prior to the one of t/sub a/. A solution for the case, where the analysis results in an impossible ordering is also presented.

This paper presents a detailed comparison between Peltier elements (also called thermoelectric coolers (TEC)) and thermoelectric generators (TEG) for the usage as thermoelectric power generators. Whereas the former is normally known for cooling applications or heat pump uses, it can also be used as generator. Today, thermoelectric energy harvesting systems find more and more utilization, e.g. in wireless sensors or exhaust pipes. The efficiency of thermoelectric materials for the low temperature sector (between 0 °C and 200 °C) is actually not very high, but the costs for TEGs are. As TECs and TEGs consist of the same thermoelectric material for this temperature sector (Bi ₂ Te ₃ ), the upcoming question is in which temperature range and under which conditions expensive TEGs can be replaced by cheap TECs. Therefore, in this contribution, TECs and TEGs are tested and compared under the same conditions.