Optimal multisensor data fusion for linear systems with missing measurements

Multisensor data fusion has attracted a lot of research in recent years. It has been widely used in many applications especially military applications for target tracking and identification. In this paper, we will handle the multisensor data fusion problem for systems suffering from the possibility of missing measurements. We present the optimal recursive fusion filter for measurements obtained from two sensors subject to random intermittent measurements. The noise covariance in the observation process is allowed to be singular which requires the use of generalized inverse. Illustration example shows the effectiveness of the proposed filter in the measurements loss case compared to the available optimal linear fusion methods.<br /

Numerical Simulation of Air Flow in Aeroengine Compressors

The performance of an aeroengine is influenced by the performance of the compressor system. A typical compressor consists of multistage axial compressors followed by a centrifugal stage. Here, a high-speed centrifugal and an axial stage are investigated in terms of turbulence modelling, flow blockage and rotor-stator (R-S) gap using the commercial software ANSYS CFX. The curvature corrected Shear stress transport (SST-CC) model of Smirnov and Menter is investigated for the first time in a high-speed centrifugal stage in terms of curvature and rotation effects. The SST-CC predictions are compared with the standard SST, Speziale, Sarkar, and Gatski Reynolds stress model (RSM-SSG) and the experimental data in terms of the global performance as well as the velocity profiles at the impeller-diffuser interface. The comparisons show that SST-CC has the best agreement with the experiments at choke condition while SST has better performance at the stall condition. The production term shows the expected sensitivity to the convex and concave curvatures. A new method to quantify blockage for both axial and centrifugal compressors is developed. Both steady and unsteady simulations are used to examine the flow blockage in the axial transonic stage. The variation of the rotor tip blockage with respect to the blade loading shows good agreement with previous studies. The total planar blockage indicates that stall might initiate at the stator trailing edge. The differences between the steady and unsteady predictions are mainly attributed to the local differences in the total pressure profiles at the inlet guide vanes–rotor interface. It was previously argued that reducing the R-S gap improves the efficiency of axial compressors due to reduced viscous mixing of the rotor wake. However, the current simulations show that the smallest R-S gap has the highest levels of total pressure losses within the stator passage and the highest levels of unsteady stator forces at reduced mass flow rates. The unsteadiness in the stator flow field is attributed to the larger stator suction surface boundary layer separation associated with the smallest gap. The smallest R-S gap reduces the viscous mixing of the wake at the expense of the efficiency

Apsorpcija urana u izoliranim i referentnim bakterijskim vrstama

In the present study, uranium absorption capacity of Bacillus pantothenticus and Bacillus megaterium, previously isolated from the environmental air surrounding the 60Co gamma source, is reported. Pseudomonas putida and Pseudomonas chlororaphis were used as reference species. Concerning uranium uptake, the local species were more efficient than the reference ones. The maximum uptake was achieved by B. megaterium and B. pantothenticus at 20 microgram U mL-1 and by B. pantothenticus at 30 microgram U mL-1. The transmission electron microscope examination indicated that uranium was absorbed onto the cell surface of the studied isolates. Furthermore, the increase in biomass concentration has shown an increase in the total amount of uranium removed. Dead cells exhibited uranium uptake to the same or greater extent than living cells. B. pantothenticus, P. putida, and P. chlororaphis achieved maximum uptake at pH 4.0, whereas B. megaterium it was pH 6.0. Temperature had an important role in uranium absorption of all the studied species except B. pantothenticus,. Metabolic inhibitors did not affect the uptake.U radu je proučavan kapacitet apsorpcije urana bakterija Bacillus pantothenticus i Bacillus megaterium izoliranih iz zraka izloženog izvoru gama-zračenja iz 60Co. Te bakterije su se pokazale učinkovitije u usporedbi s referentnim vrstama Pseudomonas putida i Pseudomonas chlororaphis. Maksimalna postignuta koncentracija bila je 10, 20, odnosno 30 µgU mL-1. Nadalje, povećanje koncentracije u biomasi pratilo je povećanje ukupne količine uklonjenog urana. Mrtve stanice su apsorbirale uran u istoj ili većoj mjeri nego žive stanice. Maksimum apsorpcije B. pantothenticus, P. putida i P. chlororaphis postignut je pri pH 4,0, a B. megaterium pri pH 6,0. Kod svih ispitivanih vrsta osim B. pantothenticus, temperatura je značajno utjecala na apsorpciju dok inhibitori metaboličkih reakcija nisu utjecali. Pretraživanje transmisijskim elektronskim mikroskopom ukazalo je da se uran apsorbirao na površinu stanice

Optimal linear data fusion for systems with missing measurements

In this paper, we provide the optimal data fusion filter for linear systems suffering from possible missing measurements. The noise covariance in the observation process is allowed to be singular which requires the use of generalized inverse. The data fusion process is made on the raw data provided by two sensors&nbsp; observing the same entity. Each of the sensors is losing the measurements in its own data loss rate. The data fusion filter is provided in a recursive form for ease of implementation in real-world applications.<br /

Robust filtering for uncertain discrete-time systems with uncertain noise covariance and uncertain observations

The use of Kalman filtering is very common in state estimation problems. The problem with Kalman filters is that they require full prior knowledge about the system modeling. It is also assumed that all the observations are fully received. In real applications, the previous assumptions are not true all the time. It is hard to obtain the exact system model and the observations may be lost due to communication problems. In this paper, we consider the design of a robust Kalman filter for systems subject to uncertainties in the state and white noise covariances. The systems under consideration suffer from random interruptions in the measurements process. An upper bound for the estimation error covariance is proposed. The proposed upper bound is further minimized by selection of optimal filter parameters. Simulation example shows the effectiveness of the proposed filter.<br /

Ablative Fractional 10 600 nm Carbon Dioxide Laser Versus Non-ablative Fractional 1540 nm Erbium-Glass Laser in Egyptian Post-acne Scar patients

Introduction: Non-ablative fractional erbium-doped glass 1540 nm and fractional ablative 10600 nm carbon dioxide lasers are regarded as effective modalities for treating acne atrophic scars. In this study, we aimed to compare the effectiveness of fractional CO2 laser and fractional non-ablative 1540 nm erbium doped glass laser in treating post acne atrophic scars in Egyptian patients.Methods: Fifty-eight patients complaining of moderate and severe acne atrophic scars were randomly divided into 2 groups of 29 patients each. Both groups were subjected to 4 treatment sessions with 3 weeks interval and were followed up for 3 months. In group A, enrolled patients received CO2 laser, while in group B, patients were treated with 1540 nm erbium glass fractional laser.Results: Clinical assessment revealed that the mean grades of progress and improvement were higher with fractional 10600 nm CO2 laser but with non-significant difference between both treatments (P = 0.1). The overall patients’ satisfaction with both lasers were not significantly different (P = 0.44).Conclusion: Both fractional ablative CO2 and fractional non-ablative erbium glass lasers are good modalities for treating acne scars with a high efficacy and safety profile and good patient satisfaction. The fractional ablative laser showed higher efficacy while non-ablative laser offered less pain and shorter downtime

Assessing gaps and needs for integrating building performance optimization tools in net zero energy buildings design

This paper summarizes a study undertaken to reveal potential challenges and opportunities for integrating optimization tools in net zero energy buildings (NZEB) design. The paper reviews current trends in simulation-based building performance optimization (BPO) and outlines major criteria for optimization tools selection and evaluation. This is based on analyzing user's needs for tools capabilities and requirement specifications. The review is carried out by means of a literature review of 165 publications and interviews with 28 optimization experts. The findings are based on an inter-group comparison between experts. The aim is to assess the gaps and needs for integrating BPO tools in NZEB design. The findings indicate a breakthrough in using evolutionary algorithms in solving highly constrained envelope, HVAC and renewable optimization problems. Simple genetic algorithm solved many design and operation problems and allowed measuring the improvement in the optimality of a solution against a base case. Evolutionary algorithms are also easily adapted to enable them to solve a particular optimization problem more effectively. However, existing limitations including model uncertainty, computation time, difficulty of use and steep learning curve. Some future directions anticipated or needed for improvement of current tools are presented.Peer reviewe

A Framework for Cost-Optimal Zero-Energy Lightweight Construction

peer reviewedDuring the last decade, several roof extensions took place in the European cities with the purpose to increase the height of existing buildings using timber as a lightweight material. However, building regulations and green codes do not usually guarantee the achievement of multi-objective and highly performance roof extensions. Accordingly, this research aims to develop a state of the art framework to achieve cost-optimal zero-energy for timber construction, specifically when building on rooftops. Through a simulated and calibrated passive house model, the boundary conditions of the study have been identified and further parametric simulation and optimization have been carried out. This research aims at linking scientific research with practice. The framework provides a fast track measurement that provides a solutions space for building engineers who are in charge of decision making on the design and construction process. Best practices of roof construction could be achieved in terms of cost and energy, giving a vast potential for a complete and deep renovation, and, therefore, reducing the overall ecological footprint on the city level

Comparing the Efficacy of Custodiol and Cold Blood Cardioplegia in Myocardial Preservation

Background: Strategies for myocardial protection vary among surgeons, and data on the optimal cardioplegia solution are insufficient. The perfect cardioplegia solution for myocardial protection during cardiac surgery is still controversial. This study aimed to compare the efficacy of custodiol and cold blood cardioplegia in preserving the myocardium. Methods: In this comparative prospective study, the patients were split into two groups of 60 patients each. Group A received Custodiol HTK solution, whereas Group B received cold blood cardioplegia. Preoperative laboratory investigations, operative data, postoperative ICU stays, and complications were compared between groups. Results: The number of cardioplegia doses was significantly greater in Group B (1.05 ± 0.22, vs. 1.90 ± 0.82; p&lt;0.001). There were no significant differences between the cardioplegia groups regarding hospital stay (p= 0.246), intensive care unit stay (p= 0.144), mortality (p= 0.769), low cardiac output (p&gt;0.99), postoperative myocardial infarction (p= 0.432), intra-aortic balloon pump insertion (p= 0.224), reoperation (p&gt;0.99), duration of mechanical ventilation (p= 0.389), pulmonary complications (p= 0.432), stroke (p&gt;0.99), or the need for renal dialysis (p= 0.559). Conclusions: Custodiol cardioplegia could be advantageous in cardiac surgeries when a longer duration is expected. However, this study did not report differences in postoperative outcomes between patients with custodiol or cold blood cardioplegia

Computationally Efficient Self-Tuning Controller for DC-DC Switch Mode Power Converters Based on Partial Update Kalman Filter

In this paper, a partial update Kalman Filter (PUKF) is presented for the real-time parameter estimation of a DC-DC switch-mode power converter (SMPC). The proposed estimation algorithm is based on a novel combination between the classical Kalman filter and an M-Max partial adaptive filtering technique. The proposed PUKF offers a significant reduction in computational effort compared to the conventional implementation of the Kalman Filter (KF), with 50% less arithmetic operations. Furthermore, the PUKF retains comparable overall performance to the classical KF. To demonstrate an efficient and cost effective explicit self-tuning controller, the proposed estimation algorithm (PUKF) is embedded with a Bányász/Keviczky PID controller to generate a new computationally light self-tuning controller. Experimental and simulation results clearly show the superior dynamic performance of the explicit self-tuning control system compared to a conventional pole placement design based on a pre-calculated average model