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We present an electromagnetic measurement system for monitoring of the effective permittivity in closed metal vessels, which are commonly used in the process industry. The measurement system exploits the process vessel as a microw...
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We present an electromagnetic measurement system for monitoring of the effective permittivity in closed metal vessels, which are commonly used in the process industry. The measurement system exploits the process vessel as a microwave cavity resonator and the relative change in its complex resonance frequencies is related to the complex effective permittivity inside the vessel. Also, thermal expansion of the process vessel is taken into account and we compensate for its influence on the resonance frequencies by means of a priori information derived from a set of temperature measurements. The sensitivities, that relate the process state to the measured resonance frequencies, are computed by means of a detailed finite element model. The usefulness of the proposed measurement system is successfully demonstrated for a pharmaceutical fluidized-bed process, where the water and solid contents inside the process vessel is of interest.
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The activated sludge process for degradation of organic matter is one of the main processes commonly used in biological wastewater treatment, and aeration in that process stands for a large part of the energy consumed in a plant. ...
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The activated sludge process for degradation of organic matter is one of the main processes commonly used in biological wastewater treatment, and aeration in that process stands for a large part of the energy consumed in a plant. Hence, there have been many attempts to improve the operation of the activated sludge process using mathematical models of the process. The advanced models used has in general their origin in IWA (former IAWQ) activated sludge model no 1 (ASM1). Unfortunately, optimization w.r.t. discharge and economy is limited for municipal wastewater treatment plants because several of the most important variables; heterotrophic biomass, readily biodegradable soluble substrate, and slowly biodegradable substrate cannot be reliably measured online because of their complexity hiding behind their notation. With the predenitrifying WWTP in Goteborg having post nitrification in trickling filters as an example, we resolve this problem by deriving an observer that estimates these concentrations in the aerobic parts based on only the commonly available online measurements of oxygen, water flows, TSS concentration and supplied air. Based on control theory analysis and simulations it is concluded that estimation does not work for an activated sludge process with aeration in one stirred tank alone, but when the activated sludge process can be described by at least two tanks in series, with oxygen measurements in each tank, the estimates converge. A sensitivity analysis with respect to deviations in model parameters reveals that the derived estimator is also fairly robust to model errors.
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Design of controllers and optimization of plants using biofilm reactors require dynamic models and efficient methods of simulation.Continuously stirred biofilm reactors (CSBRs) are useful model units in modeling a variety of diffe...
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Design of controllers and optimization of plants using biofilm reactors require dynamic models and efficient methods of simulation.Continuously stirred biofilm reactors (CSBRs) are useful model units in modeling a variety of different types of biofilm reactors.Often the reaction kinetics in the biofilm is described by a Monod expression.With standard modeling assumptions the equations describing the fast dynamics of a CSBR will then,for each substrate,be one nonlinear partial differential equation coupled with one linear ordinary differential equation.Here,it is shown how a few nonlinear ordinary first order differential equations,which may be solved with standard integration methods,can be used as a close approximation for both dynamic responses and steady state solutions.These low order models can conveniently be used in simulation software and for controller design.
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We present a method for compensating laser attenuation in optically dense sprays, in particular for use in combustion engine research. Images of the fuel sprays are produced by planar laser imaging, where Mie scattered light from ...
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We present a method for compensating laser attenuation in optically dense sprays, in particular for use in combustion engine research. Images of the fuel sprays are produced by planar laser imaging, where Mie scattered light from a cross section of the spray is imaged onto a CCD camera. The compensation scheme is based on the Beer-Lambert law, which is used here to sum up the loss of light along the path of the laser in the image, and to compensate iteratively, pixel by pixel, for this loss.
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We report that GABAA receptors in a patch-clamped biological cell form a short-term memory circuit when integrated with a scanning-probe microfluidic device.Laminar patterns of receptor activators(agonists)provided by the microflu...
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We report that GABAA receptors in a patch-clamped biological cell form a short-term memory circuit when integrated with a scanning-probe microfluidic device.Laminar patterns of receptor activators(agonists)provided by the microfluidic device define and periodically update the data input which is read and stored by the receptors as state distributions(based on intrinsic multistate kinetics).The memory is discharged over time and lasts for seconds to minutes depending on the input function.The function of the memory can be represented by an equivalent electronic circuit with striking similarity in function to a dynamic random access memory(DRAM)used in electronic computers.Multiplexed biohybrid memories may form the basis of large-scale integrated biocomputational/sensor devices with the curious ability to use chemical signals including odorants,neurotransmitters,chemical and biological warfare agents,and many more as input signals.
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A Bayesian approach to estimate parameters of signals embedded in complex Gaussian noise with unknown color is presented. The study specifically focuses on a Bayesian treatment of the unknown noise covariance matrix making up a nu...
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A Bayesian approach to estimate parameters of signals embedded in complex Gaussian noise with unknown color is presented. The study specifically focuses on a Bayesian treatment of the unknown noise covariance matrix making up a nuisance parameter in such problems. By integrating out uncertainties regarding the noise color, an enhanced ability to estimate both the signal parameters as well as properties of the error is exploited. Several noninformative priors for the covariance matrix, such as the reference prior, the Jeffreys prior, and modifications to this, are considered. Some of the priors result in analytical solutions, whereas others demand numerical approximations. In the linear signal model, connections are made between the standard Adaptive Maximum Likelihood (AML) estimate and a Bayesian solution using the Jeffreys prior. With adjustments to the Jeffreys prior, correspondence to the regularized solution is also established. This in turn enables a formal treatment of the regularization parameter. Simulations indicate that significant improvements, compared to the AML estimator, can be obtained by considering both the derived regularized solutions as well as the one obtained using the reference prior. The simulations also indicate the possibility of enhancing the predictions of properties of the error as uncertainties in the noise color are acknowledged.
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This study describes the design and experimental verification of the ridge gap waveguide, appearing in the gap between parallel metal plates. One of the plates has a texture in the form of a wave-guiding metal ridge surrounded by ...
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This study describes the design and experimental verification of the ridge gap waveguide, appearing in the gap between parallel metal plates. One of the plates has a texture in the form of a wave-guiding metal ridge surrounded by metal posts. The latter posts, referred to as a pin surface or bed of nails, are designed to give a stopband for the normal parallel-plate modes between 10 and 23 GHz. The hardware demonstrator includes two 908 bends and two capacitive coupled coaxial transitions enabling measurements with a vector network analyser (VNA). The measured results verify the large bandwidth and low losses of the quasitransverse electromagnetic (TEM) mode propagating along the guiding ridge, and that 908 bends can be designed in the same way as for microstrip lines. The demonstrator is designed for use around 15 GHz. Still, the ridge gap waveguide is more advantageous for frequencies above 30 GHz, because it can be realised entirely from metal using milling or moulding, and there are no requirements for conducting joints between the two plates that otherwise is a problem when realising conventional hollow waveguides.
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The paper presents an efficient method for the design of printed microstrip circuit with packaging in mind, referred to as numerical prepackaging with a perfectly magnetic conductive (PMC) lid. The method comprises making the desi...
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The paper presents an efficient method for the design of printed microstrip circuit with packaging in mind, referred to as numerical prepackaging with a perfectly magnetic conductive (PMC) lid. The method comprises making the design including the packaging from the start by using a PMC lid, rather than first designing the open-aired circuit; and thereafter, considering the packaging effect and the often required retuning of the circuits themselves. The advantage is that no parallel plate modes can propagate between the perfect electric conductor (PEC) ground plane and the PMC lid plate if the spacing is smaller than an effective quarter of wavelength. This provides a limited computational volume so that the computation time is significantly reduced in the case of the finite element method (FEM) or the finite difference time domain method (FDTD). By using numerical packaging with PMC lid, the ideal PMC lid has to be realized afterwards e.g. by using a lid of nails, which is a minor task as compared to existing approaches.
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Two methods, both based on the concept of combustion net torque, for estimation of combustion properties using measurements of crankshaft torque data are investigated in this work. The first of the proposed methods estimates entir...
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Two methods, both based on the concept of combustion net torque, for estimation of combustion properties using measurements of crankshaft torque data are investigated in this work. The first of the proposed methods estimates entire burned mass fraction traces from corresponding combustion net torque traces. This is done by solving a convex optimization problem that is based on a derived analytical relation between the two quantities. The other proposed estimation method estimates the well established combustion phasing measure referred to as 50% burned mass fraction directly from combustion net torque using a nonlinear black-box mapping. The methods are assessed using both simulations and experimental data gathered from a 5-cylinder light-duty diesel engine equipped with a crankshaft torque sensor and cylinder pressure sensors that are used for reference measurements. The results indicate that both methods work well but the method that estimates entire burned mass fraction traces is more sensitive to torque data quality. Based on the experimental crankshaft torque data, the direct combustion phasing estimation method delivers estimates with a bias of less than 1 CAD and a cycle-to-cycle standard deviation of less than 2.7 CAD for all cylinders.
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Methods for closed-loop combustion phasing control in a diesel engine, based on measurements of crankshaft torque, are developed and evaluated. A model-based method for estimation of cylinder individual torque contributions from t...
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Methods for closed-loop combustion phasing control in a diesel engine, based on measurements of crankshaft torque, are developed and evaluated. A model-based method for estimation of cylinder individual torque contributions from the crankshaft torque measurements is explained and a novel approach for identification of crankshaft dynamics is proposed. The use of the combustion net torque concept for combustion phasing estimation in the torque domain is also described. Two different control schemes, one for individual cylinder control and one for average cylinder control, are studied. The proposed methods are experimentally evaluated using a light-duty diesel engine equipped with a crankshaft integrated torque sensor. The results indicate that it is possible to estimate and control on a cylinder individual basis using the measurements from the crankshaft torque sensor. Combustion phasing is estimated with bias levels of less than 0.5 crank angle degrees (CAD) and cycle-to-cycle standard deviations of less than 0.7 CAD for all cylinders and the implemented combustion phasing controllers manage to accurately counteract disturbances in both fuel injection timing and EGR fraction.
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