The modelling and simulation of a drying process in a poultry by-product processing plant

This paper studies the modelling and simulation of a drying process in a poultry by-product processing plant. In a poultry by-product processing plant, the material is separated into liquids, fats and solids. The liquids are removed, either by pressing or drying, the fats are collected in a centrifuge and the solid mass is dried and manufactured into a protein-rich solid powder. The process contains two rendering operations, where heat is applied to the material to both remove extra moisture and to raise the temperature of the material. These processes are vital for the sterilization of the material as well as for the quality of the product. To improve the understanding behind the drying process, a mathematical model is created using first principles and the obtained model is complemented with experimental data from the real-world process to produce a dynamic model of the drying process. The model is built on a digital computer, using a simulation software. The model is validated with data from the real process plant and used to reveal the underlying dynamics that complicate the control of the process. The model enables the design of automatic control for the process in a safe environment.publishedVersionPeer reviewe

Self heating of piezoelectric actuators. measurement and compensation

This paper introduces the effect of self heating on the displacement of piezoelectric actuators and a novel method to quantify self heating. Issues influencing self heating include; the frequency and the amplitude of the driving voltage, and the size, or more specifically the volume-area ratio of the actuator and they are also discussed. The effect of a load on the heat generation is studied. According to the experiments, the peakto- peak value of the consumed current is a good indication of the temperature rise of the actuator. This can be used for the protection of the actuator from overheating, or as the authors will propose in the paper, it can be used to compensate for the changes in the displacement induced by the self heating. The displacement error of the heated actuator reduces in average down to one part in three when the proposed compensation is used.Peer reviewe

Estimation of electrical cell-capillary admittance during injection with frequency response method

This paper describes electrical equivalent circuit models of cell–capillary admittance during injection of a living cell and presents a measurement system to estimate corresponding frequency responses during microinjection tests. Since the admittance estimate is calculated from data collected during injection, the amount of data is limited. To overcome this constraint, the approach proposed in this paper takes advantage of properties of periodic pseudo random binary sequence (PRBS) excitation signal and avoids end effect anomalies of correlation calculation. The fast and accurate estimation is used to detect the degree of contact during cell injection and to detect breakage and clogging of capillary during a sequence of multiple operations.Peer reviewe

Rapid High-Frequency Measurements of Electrical Circuits by Using Frequency Mixer and Pseudo-Random Sequences

Frequency-response measurements at high frequencies have been shown to provide a valuable design tool in various fields of electronics. These measurements are often challenging when using most commercially available measurement tools due to their relatively low maximum sampling frequency and long measurement time. This effectively prevents frequency-response-based low-cost applications where fast and reliable measurements are required. This paper proposes the use of a combined frequency mixer applied with pseudo-random sequences. In this method, the applied pseudo-random excitation is upconverted to high frequencies by the mixer, and once injected into the device being tested, the system response is downconverted to lower frequencies. The method provides a low-cost solution that can be applied for rapid high-frequency measurements by using only modest data-acquisition tools. Experimental results based on a high-frequency resonator are presented and used to demonstrate the effectiveness of the proposed methods