Robust stability conditions for polytopic systems

The paper provides a survey of some recent robust stability conditions, their mutual comparisons, and presents new robust stability conditions for continuous- and discrete-time systems with convex polytopic uncertainty. Robust stability analysis is based on LMI conditions and parameter-dependent Lyapunov functions. The developed stability conditions are appropriate for output feedback design. Numerical examples thoroughly illustrate the power of the considered robust stability analysis methods and show which of them provides the less conservative results.     

Trading between quality and non-functional properties of median filter in embedded systems

Genetic improvement has been used to improve functional and non-functional properties of software. In this paper, we propose a new approach that applies a genetic programming (GP)-based genetic improvement to trade between functional and non-functional properties of existing software. The paper investigates possibilities and opportunities for improving non-functional parameters such as execution time, code size, or power consumption of median functions implemented using comparator networks. In general, it is impossible to improve non-functional parameters of the median function without accepting occasional errors in results because optimal implementations are available. In order to address this issue, we proposed a method providing suitable compromises between accuracy, execution time and power consumption. Traditionally, a randomly generated set of test vectors is employed so as to assess the quality of GP individuals. We demonstrated that such an approach may produce biased solutions if the test vectors are generated inappropriately. In order to measure the accuracy of determining a median value and avoid such a bias, we propose and formally analyze new quality metrics which are based on the positional error calculated using the permutation principle introduced in this paper. It is shown that the proposed method enables the discovery of solutions which show a significant improvement in execution time, power consumption, or size with respect to the accurate median function while keeping errors at a moderate level. Non-functional properties of the discovered solutions are estimated using data sets and validated by physical measurements on physical microcontrollers. The benefits of the evolved implementations are demonstrated on two real-world problems—sensor data processing and image processing. It is concluded that data processing software modules offer a great opportunity for genetic improvement. The results revealed that it is not even necessary to determine the median value exactly in many cases which helps to reduce power consumption or increase performance. The discovered implementations of accurate, as well as approximate median functions, are available as C functions for download and can be employed in a custom application (http://www.fit.vutbr.cz/research/groups/ehw/median).     

Gain-scheduled PID controller design

Gain scheduling (GS) is one of the most popular approaches to nonlinear control design and it is known that GS controllers have a better performance than robust ones. Following the terminology of control engineering, linear parameter-varying (LPV) systems are time-varying plants whose state space matrices are fixed functions of some vector of varying parameters. Our approach is based on considering that the LPV system, scheduling parameters and their derivatives with respect to time lie in a priori given hyper rectangles. To guarantee the performance we use the notion of guaranteed costs. The class of control structure includes centralized, decentralized fixed order output feedbacks like PID controller. Numerical examples illustrate the effectiveness of the proposed approach.     

Specific Magnetic Isolation of E6 HPV16 Modified Magnetizable Particles Coupled with PCR and Electrochemical Detection

The majority of carcinomas that were developed due to the infection with human papillomavirus (HPV) are caused by high-risk HPV types, HPV16 and HPV18. These HPV types contain the E6 and E7 oncogenes, so the fast detection of these oncogenes is an important point to avoid the development of cancer. Many different HPV tests are available to detect the presence of HPV in biological samples. The aim of this study was to design a fast and low cost method for HPV identification employing magnetic isolation, polymerase chain reaction (PCR) and electrochemical detection. These assays were developed to detect the interactions between E6-HPV16 oncogene and magnetizable particles (MPs) using commercial Dynabeads M-280 Streptavidin particles and laboratory-synthesized “homemade” particles called MANs (MAN-37, MAN-127 and MAN-164). The yields of PCR amplification of E6-HPV16 oncogene bound on the particles and after the elution from the particles were compared. A highest yield of E6-HPV16 DNA isolation was obtained with both MPs particles commercial M-280 Streptavidin and MAN-37 due to reducing of the interferents compared with the standard PCR method. A biosensor employing the isolation of E6-HPV16 oncogene with MPs particles followed by its electrochemical detection can be a very effective technique for HPV identification, providing simple, sensitive and cost-effective analysis.     

A Genetic Programming Approach to System Identification of Rainfall-Runoff Models

Advancements in data acquisition, storage and retrieval are progressing at an extraordinary rate, whereas the same in the field of knowledge extraction from data is yet to be accomplished. The challenges associated with hydrological datasets, including complexity, non-linearity and multicollinearity, motivate the use of machine learning to build hydrological models. Increasing global climate change and urbanization call for better understanding of altered rainfall-runoff processes. There is a requirement that models are intelligible estimates of underlying physics, coupling explanatory and predictive components, maintaining parsimony and accuracy. Genetic Programming, an evolutionary computation technique has been used for short-term prediction and forecast in the field of hydrology. Advancing data science in hydrology can be achieved by tapping the full potential of GP in defining an evolutionary flexible modelling framework that balances prior information, simulation accuracy and strategy for future uncertainty. As a preliminary step, GP is used in conjunction with a conceptual rainfall-runoff model to solve model configuration problem. Two datasets belonging to a tropical catchment of Singapore and a temperate catchment of South Island, New Zealand with contrasting characteristics are analyzed in this study. The results indicate that proposed approach successfully combines the merits of evolutionary algorithm and conceptual knowledge in the generation of optimal model structure and associated parameters to capture runoff dynamics of catchments.     

Sarcosine as a Potential Prostate Cancer Biomarker—A Review

Prostate cancer (CaP) is the most common type of tumour disease in men. Early diagnosis of cancer of the prostate is very important, because the sooner the cancer is detected, the better it is treated. According to that fact, there is great interest in the finding of new markers including amino acids, proteins or nucleic acids. Prostate specific antigen (PSA) is commonly used and is the most important biomarker of CaP. This marker can only be detected in blood and its sensitivity is approximately 80%. Moreover, early stages cannot be diagnosed using this protein. Currently, there does not exist a test for diagnosis of early stages of prostate cancer. This fact motivates us to find markers sensitive to the early stages of CaP, which are easily detected in body fluids including urine. A potential is therefore attributed to the non-protein amino acid sarcosine, which is generated by glycine-N-methyltransferase in its biochemical cycle. In this review, we summarize analytical methods for quantification of sarcosine as a CaP marker. Moreover, pathways of the connection of synthesis of sarcosine and CaP development are discussed.     

Voltammetry as a Tool for Characterization of CdTe Quantum Dots

Electrochemical detection of quantum dots (QDs) has already been used in numerous applications. However, QDs have not been well characterized using voltammetry, with respect to their characterization and quantification. Therefore, the main aim was to characterize CdTe QDs using cyclic and differential pulse voltammetry. The obtained peaks were identified and the detection limit (3 S/N) was estimated down to 100 fg/mL. Based on the convincing results, a new method for how to study stability and quantify the dots was suggested. Thus, the approach was further utilized for the testing of QDs stability.     

Molecular fluorinated alumoxanes: One step towards well-defined fluorinated alumina

The unprecedented molecular alumoxane [{LAl(F)}₂(μ-O)] (2) is easily accessible from the reaction between [{LAl(H)}₂(μ-O)] (1) and the mild fluorinating agent Me₃SnF. Furthermore, the controlled hydrolysis of 2 led to the preparation of the binuclear aluminum hydroxyfluoride [{LAl(F)(μ-OH)}₂] (3) in a straightforward manner. The compounds were characterized by spectroscopic techniques (IR, EI–MS, solid state MAS NMR (¹³C and ²⁷Al), solution NMR (¹H, ¹³C, ¹⁹F and ²⁷Al)) and in the case of 3, through X-ray diffraction studies. Compound 3 represents the first example of a molecular aluminum hydroxyfluoride fully structurally characterized.     

Influence of the surface etching on the corrosion behaviour of a three-dimensional printed Ti–6Al–4V alloy

Recently, there has been an extension of three-dimensional (3D) printing technology of metal materials in the medical field. Additive technology has made it possible to manufacture customized implants. However, 3D printing products often require surface treatment. The possible treatments include acid etching. This study investigated the effect of surface etching on the corrosion resistance of Ti–6Al–4V alloy concerning biological applications. The samples were etched in a mixture of hydrofluoric acid and nitric acid. The corrosion behaviour was described by measuring the time dependence of polarization resistance in a saline solution and surface analysis. The results showed that etching creates a fluoride-rich layer on the surface, which negatively affects the corrosion behaviour of the material for up to 24 hr. Cytocompatibility tests showed that the resulting layer does not affect the biocompatibility of the material.     

Dietary purines in vegetarian meat analogues

BACKGROUND: The meat alternatives market offers a wide range of products resembling meat in taste, flavour or texture but based on vegetable protein sources. These high protein–low purine foods may find application in a low purine or purine‐free diet, which is sometimes suggested for subjects with increased serum urate levels, i.e. hyperuricaemia. RESULTS: We determined purine content (uric acid, adenine, guanine, hypoxanthine, xanthine) in 39 commercially available meat substitutes and evaluated them in relation to their protein content. Some of the products contained a comparable sum of adenine and hypoxanthine per protein as meat. Analysis of variance showed an influence of protein source used. Mycoprotein‐based products had significantly higher contents (2264 mg kg^?1) of adenine and hypoxanthine per kg of 100% protein than soybean‐based products (1648 mg kg^?1) or mixtures consisting of soybean protein and wheat protein (1239 mg kg^?1). CONCLUSION: Protein‐rich vegetable‐based meat substitutes might be generally accepted as meat alternatives for individuals on special diets. The type of protein used to manufacture these products determines the total content of purines, which is relatively higher in the case of mycoprotein or soybean protein, while appearing lower in wheat protein and egg white‐based products. These are therefore more suitable for dietary considerations in a low‐purine diet for hyperuricaemic subjects. Copyright © 2010 Society of Chemical Industry