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This paper aims to describe a method for efficient frequency domain model order reduction. The method attempts to combine the desirable attributes of Krylov reduction and proper orthogonal decomposition (POD) and is entitled Krylov enhanced POD (KPOD).

The KPOD method couples Krylov’s moment-matching property with POD’s data generalization ability to construct reduced models capable of maintaining accuracy over wide frequency ranges. The method is based on generating a sequence of state- and frequency-dependent Krylov subspaces and then applying POD to extract a single basis that generalizes the sequence of Krylov bases.

The frequency response of a pre-stressed microelectromechanical system resonator is used as an example to demonstrate KPOD’s ability in frequency domain model reduction, with KPOD exhibiting a 44 per cent efficiency improvement over POD.

The results indicate that KPOD greatly outperforms POD in accuracy and efficiency, making the proposed method a potential asset in the design of frequency-selective applications.

Gas insulated systems, such as gas insulated lines (GIL), use insulating gas, mostly sulfur hexalfluoride (SF₆), to enable a higher dielectric strength compared to e.g. air. However, under high voltage direct current conditions, charge accumulation and electric field stress may occur, which may lead to partial discharge or system failure. Therefore, numerical simulations are used to design the system and determine the electric field and charge distribution. Although the gas conduction shows a more complex current–voltage characteristic compared to solid insulation, the electric conductivity of the SF₆ gas is set as constant in most works. The purpose of this study is to investigate different approaches to address the conduction in the gas properly for numerical simulations.

In this work, two approaches are investigated to address the conduction in the insulating gas and are compared to each other. One method is an ion-drift-diffusion model, where the conduction in the gas is described by the ion motion in the SF₆ gas. However, this method is computationally expensive. Alternatively, a less complex approach is an electro-thermal model with the application of an electric conductivity model for the SF₆ gas. Measurements show that the electric conductivity in the SF₆ gas has a nonlinear dependency on temperature, electric field and gas pressure. From these measurements, an electric conductivity model was developed. Both methods are compared by simulation results, where different parameters and conditions are considered, to investigate the potential of the electric conductivity model as a computationally less expensive alternative.

The simulation results of both simulation approaches show similar results, proving the electric conductivity for the SF₆ gas as a valid alternative. Using the electro-thermal model approach with the application of the electric conductivity model enables a solution time up to six times faster compared to the ion-drift-diffusion model. The application of the model allows to examine the influence of different parameters such as temperature and gas pressure on the electric field distribution in the GIL, whereas the ion-drift-diffusion model enables to investigate the distribution of homo- and heteropolar charges in the insulation gas.

This work presents numerical simulation models for high voltage direct current GIL, where the conduction in the SF₆ gas is described more precisely compared to a definition of a constant electric conductivity value for the insulation gas. The electric conductivity model for the SF₆ gas allows for consideration of the current–voltage characteristics of the gas, is computationally less expensive compared to an ion-drift diffusion model and needs considerably less solution time.

The purpose of this paper is to design an out-of-plane micro electro-thermal-compliant actuator based logic gates which work analogously to complementary metal oxide semiconductor (CMOS) based logic gates. The proposed logic gates used a single-bit mechanical micro ETC actuator per logic instead of using 6-14 individual transistors as in CMOS.

A complete analytical modelling is performed on a single ETC vertical actuator, and a relation between the applied voltage and the out-of-plane deflection is derived. Its coupled electro-thermo-mechanical analysis is carried out using micro electro mechanical system (MEMS) CAD tool CoventorWare to illustrate its performance.

This paper reports analytical and numerical simulation of basic MEMS ETC actuator-based logic gates. The proposed logic gate operates on 5 V, which suits well with conventional CMOS logic, which in turn reduces the power consumption of the device.

The proposed logic gates uses a single-bit MEMS ETC actuator per logic instead of using more transistors as in CMOS. The unique feature of this proposed logic gates is that the basic mechanical ETC actuator is customized in its structure to function as specific logic gates depending upon the given inputs.

The purpose of this paper is to explore a new possibility of providing high-temperature stable lead-free interconnections for low-temperature co-fired ceramics (LTCC) hotplate. For gas-sensing application, a temperature range of 200°C-400°C is usually required by the sensing film to detect different gases which imply the requirement of thermally stable interconnects. To observe the effect of parameters influencing power of the device, electro-thermal simulation of LTCC hotplate is also presented. Simulated LTCC hotplate is fabricated using the LTCC technology.

The proposed task is to fabricate LTCC hotplate with interconnects through vertical access. Dedicated via-holes generated on the LTCC hotplate are used to provide the interconnections. These interconnections are based on adherence and bonding mechanism between LTCC and thick film. COMSOL software is used for finite element method (FEM) simulation of the LTCC hotplate structure.

Thermal reliability of these interconnections is tested by continuous operation of hotplate at 350°C for 175 h and cycling durability test performed at 500°C. Additionally, vibration test is also carried out for the hotplate with no damage observed in the interconnections. An optimized firing profile to reproduce these interconnections along with the experimental flowchart is presented.

Research activity includes design and fabrication of LTCC hotplate with metal to thick-film based interconnections through vertical access. Research work on interconnections based on adherence of LTCC and thick film is limited.

A new way of providing lead-free and reliable interconnections will be useful for gas sensor fabricated on LTCC substrate. The FEM results are useful for optimizing the design for developing low-power LTCC hotplate.

Adherence and bonding mechanism between LTCC and thick film can be used to provide interconnections for LTCC devices. Methodology for providing such interconnections is discussed.

Multiphysics problems are solved either with monolithic or segregated approaches. For accomplishing contrary discretisation requirements of the physics, disparate meshes are essential. This paper is comparing experimental results of different interpolation methods for a segregated coupling with monolithic approaches, implemented using a global and a local nearest neighbour method. The results show the significant influence of discretisation for multiphysics simulation.

Applying disparate meshes to the monolithic as well as the segregated calculation of finite element problems and evaluating the related numerical error is content of the contribution. This is done by an experimental evaluation of a source and a material coupling applied to a multiphysics problem. After an introduction to the topic, the evaluated multiphysics model is described based on two bidirectional coupled problems and its finite element representation. Afterwards, the considered methods for approximating the coupling are introduced. Then, the evaluated methods are described and the experimental results are discussed. A summary concludes this work.

An experimental evaluation of the numerical errors for different multiphysics coupling methods using disparate meshes is presented based on a bidirectional electro-thermal simulation. Different methods approximating the coupling values are introduced and challenges of applying these methods are given. It is also shown, that the approximation of the coupling integrals is expensive. Arguments for applying the different methods to the monolithic and the segregated solution strategies are given and applied on the example. The significant influence of the mesh density within the coupled meshes is shown. Since the projection and the interpolation methods do influence the result, a careful decision is advised.

In this contribution, existing coupling methods are described, applied and compared on their application for coupling disparate meshes within a multiphysics simulation. Knowing their performance is relevant when deciding for a monolithic or a segregated calculation approach with respect to physics dependent contrary discretisation requirements. To the authors’ knowledge, it is the first time these methods are compared with a focus on an application in multiphysics simulations and experimental results are discussed.

Power modules including the insulated gate bipolar transistor (IGBT) are widely used in the applications of motor drivers. The thermal behavior of these modules makes it important to choose the optimum design of cooling system. The purpose of this paper is to propose an RC thermal model of the dynamic electro‐thermal behavior of IGBT pulse width modulation inverter modules.

The electrothermal model has been implemented and simulated with a MATLAB simulator and takes into account the thermal influence between the different module chips based on the technique of superposition.

This study has led to a correction of the junction temperature values estimated from the transient thermal impedance of each component operating alone.

In this paper, an experimental technique of a thermal influence evaluation is presented.

This study aims to couple two codes, one able to perform icing simulations and another one capable to simulate the performance of an electrothermal anti-icing system in an integrated fashion.

The classical tool chain of icing simulation (aerodynamics, water catch and impact, mass and energy surface balance) is coupled to the thermal analysis through the surface substrate and the ice thickness. In the present approach, the ice protection simulation is not decoupled from the ice accretion simulation, but a single computational workflow is considered.

A fast approach to simulate advanced anti-icing systems is found in this study.

This study shows the validation of present procedure against literature data, both experimental and numerical.

In high voltage direct current cable systems, cable joints are known as the least reliable components due to the use of multiple dielectrics. Resulting from the electric field and temperature depending conductivity of the different dielectrics, field enhancement at critical areas, e.g. triple points, may result in accelerated aging and the failure of the component. To reduce the stress, different field grading techniques are applied. The purpose of this study is to investigate different grading techniques for cable joints. Different shapes of the electrode and a varying nonlinear conductivity of field grading materials (FGM) are used for the simulation of the electric field.

Coupled electro-thermal field simulations are applied for different joint geometries, to obtain the stationary electric field. Electric field simulations in cable joint using geometric and nonlinear field grading techniques are shown.

Using the geometric field grading, the shape of the stress cone determines the field values in critical areas (triple points). High stress reduction is obtained for a certain curvature of the stress cone. For the nonlinear stress control, materials with a higher conductivity in comparison to the cable and the joint material are used. A field reduction is obtained by increasing the total conductivity. On the other hand, this is also increasing the insulation losses within the total FGM. More applicable is the decrease of the switching field or the increase of nonlinearity, which is only locally increase the conductivity and the insulation losses. Furthermore, simulations results show that an approximately constant field reduction is obtained, if the nonlinearity is above a certain threshold.

This study is restricted to a field dependency of FGM only. For impulse voltages, high temperature and electric conductivity values my result in a thermal runaway. Furthermore, only direct current field grading techniques are studied.

The field grading of cable joints, using geometric and nonlinear techniques, is analyzed. A comparison between the electric field, by varying the curvature of the ground stress cone or the FGM conductivity constants in a complex joint geometry is novel. With its effect on the electric fields, general requirements for the geometry (geometric field grading) or the values of the FGM constants (nonlinear field grading) are defined to obtain a sufficient field grading.

Low temperature co-fired ceramics (LTCC) technology-based micro-hotplates are of immense interest owing to their ruggedness, high temperature stability and reliability. The purpose of this paper is to study the role of thermal mass of LTCC-based micro-hotplates on the power consumption and temperature for gas-sensing applications.

The LTCC micro-hotplates with different thicknesses are designed and fabricated. The role of thermal mass on power consumption and temperature of these hotplates are simulated and experimentally studied. Also, a comparison study on the performance of LTCC and alumina-based hotplates of equivalent thickness is done. A thick film-sensing layer of tin oxide is coated on LTCC micro-hotplate and demonstrated for the sensing of commercial liquefied petroleum gas.

It is found from both simulation and experimental studies that the power consumption of LTCC hotplates was decreasing with the decrease in thermal mass to attain the same temperature. Also, the LTCC hotplates are less power-consuming than alumina-based one, owing to their superior thermal characteristics (low thermal conductivity, 3.3 W/ [m-K]).

This study will be beneficial for designing hotplates based on LTCC technology with low power consumption and better stability for gas-sensing applications.

The purpose of this paper is to help reduce power consumption by using platinum‐based microhotplate with different dielectric membranes SiO2 and Si3N4 for gas sensing applications, and to develop platinum lift‐off process using DC sputtering method for fabrication of platinum resistor.

Semiconductor gas sensors normally require high power consumption because of their elevated operating temperature 300‐600°C. Considering the thermal resistant and sensitive characteristics of metal platinum as well as heat and electricity insulating characteristics of SiO2, Si3N4 and combination of both, a kind of the Si‐substrate microhotplate was designed and simulated using ANSYS 10.0 tool. Thermal oxidation of Si wafer was carried out to get a 1.0 μm thick SiO2 layer. Pt deposition on oxidized silicon substrate by lift‐off was carried out using DC sputtering technique.

The platinum‐based microhotplate requires 31.3‐70.5 mW power to create the temperature 348‐752°C for gas sensing applications. The SiO2 membrane can operate the gas sensitive film at higher temperature than the Si3N4 and combination of both the membranes at same power consumption. The paper also presents the FEM simulation of different heating elements like nichrome and tantalum and its comparison to platinum for microhotplate applications.

Both the simulation and experimental work provides the low cost, high yield and repeatability in realization of microhotplate. The design and simulation work provides the better selection of heating elements and dielectric membranes. The developed experimental process provides the easy fabrication of platinum resistors using DC sputtering technique.