Simulation is the process of computing a behavior determined by a given model of a system of interest.  Modeling is the process of creating a model that formally describes a given class of system.  Modeling and simulation can be used to quickly and cheaply study and understand new technologies.  Today, a wide range of systems are simulated using different tools.  However, converting models into simulation codes can still be difficult and time consuming. In this thesis, we study how a new modeling and simulation language called Acumen can be used to model basic physical links.  This language is aimed at bridging the gap between modeling and simulation.  We focus on basic physical links as an interesting type of system to model and simulate. We also focus on comparing Acumen to MATLAB and Simulink.  The types of links we consider include models of an RC low-pass filter, Amplitude Modulation, Frequency Modulation, Amplitude Shift Keying, Phase Shift Keying and Frequency Shift Keying systems. Each of these examples is modeled in Acumen, MATLAB and Simulink. We find that, for the most part, Acumen allows us to naturally express a wide range of modulation techniques mentioned above. When compared to MATLAB ad Simulink, we find that Acumen is simple language to understand. Acumen codes are described in a more natural way. Simplicity is the biggest advantage of Acumen.

In this study, a novel and systematic methodology for the design and optimization of lowpass filters (LPFs), and multiorder-bandpass filters (BPFs) are proposed. The width of the LPF signal traces consistently follow Fourier truncated series, and the thickness of the substrate as well. By studying different lengths and other physical constraints, the design meets predefined electrical requirements. Moreover, superformula is used in split ring resonators (SRRs) designs to obtain a BPF response and significant structural compactness. Non-uniform transmission lines, as well as superformula equations, are programmed in MATLAB, which is also used for analytical validations. Traces are drawn in AutoCAD. The substrate of LPF is constructed in Pro/e. Finally, the optimized layouts are imported to Ansys High Frequency Structure Simulation (HFSS) software for simulation and verification. Nonuniform LPFs are optimized over a range of 0-6 GHz with cutoff frequency 3.5 GHz. Superformula implemented multiorder-BPFs are optimized with cutoff frequency of 1.1 GHz.

Fordonsindustrin är inne i ett skifte, där förbränningsmotorer (ICE) bör-jar fasas ut och det satsas mer på eldrift med hjälp av batterier (BEV).  I detta arbete, som efterfrågades av Volvo Cars, utvecklades en matema-tisk modell som uppskattar den lägsta temperaturen i en elbils högspän-ningsbatteri. Modellen delades initialt upp i två delar, där den ena delen utgick från hur omgivningstemperaturen samt fordonets hastighet på-verkar eventuell värmeövergång mellan batteri och omgivning. Den andra delen utgick från hur batteriets kylsystem påverkar batteriets temperatur, där kylsystemets temperatur och flöde var de styrande fak-torerna. De styrande variablerna filtrerades med lågpassfilter där olika tidskonstanter användes. Den del som för varje tillfälle visade lägst tem-peratur var gällande. Modellen togs fram med hjälp av mätdata från testkörningar i kallt klimat där testbilens batteri var preparerad med ett antal externa temperatur sensorer, och de preparerade sensorerna an-sågs visa batteriets verkliga temperatur. Tidiga resultat visade att mo-dellen för omgivningstemperatur och hastighet visade relativt bra vär-den men saknade inflytande från kylsystemets dynamik medan mo-dellen för kylsystemet fungerade mindre bra i de flesta fall. Modellen modifierades därför till att ha hastighet och omgivningstemperatur som basfunktion och kylsystemets påverkan adderades. Resultatet visade att den senare modellen hanterade systemets dynamik bättre än tidigare modell. I framtida studier bör batteriets termiska massa samt dess egen-uppvärmning tas i beaktning. / The automotive industry is shifting from internal combustion engines (ICE) cars to battery electric vehicles (BEV). In this work, requested by Volvo Cars, a mathematical model was developed that estimates the lowest temperature of an electric car's high-voltage battery. The model was initially divided into two parts, where one part was based on how the ambient temperature and the vehicle's speed affect any heat transfer between battery and surroundings. While the second part was based on how the battery's cooling system affects the battery temperature, where the cooling system temperature and flow were the controlling factors. The controlling variables were filtered with low-pass filters where dif-ferent time constants were used. The part that showed the lowest tem-perature for each occasion was valid. The model was developed using measurement data from test runs in cold climates where the test car's battery was prepared with more temperature sensors than are in a pro-duction battery and the prepared sensors were considered to show the battery's actual temperature. Early results showed that the ambient tem-perature and speed model showed relatively good values but lacked in-fluence from the cooling system, while the model for the cooling system worked less well in most cases. The model was therefore modified to have speed and ambient temperature as the base function and the cool-ing system's impact was added. The results showed that the latter model handled the dynamics of the system better than the previous model. In future studies, the thermal mass of the battery and its self-heating should be considered.

The thesis deals with the microstrip filter design using defected ground structure (DGS). The difference between standard asymmetric microstrip technique and DGS is in using the structures etched in the microwave substrate ground plane. The DGS resonant characteristics are then used in filter design. The thesis consists of three factual parts. The first one (chapter 4) introduces the use of the DGS resonators in the lowpass filter design. It involves experimental analysis of one type of the lowpass filter. The second part (chapter 5) deals with a novel microstrip lowpass filter design method using DGS. The proposed method is verified by simulations and several samples are realized and measured. Finally, the third part (chapters 7 and 8) deals with the bandpass filter design using specific defected ground structure as a resonator. The resonators are used in a coupled resonator structure. Filters of various orders and resonator configurations are designed and simulated. A combination of the DGS resonators and half-wavelength microstrip resonators is introduced as well. Selected samples are realized and measurement results are compared with simulations.