Regime variance testing - a quantile approach

This paper is devoted to testing time series that exhibit behavior related to two or more regimes with different statistical properties. Motivation of our study are two real data sets from plasma physics with observable two-regimes structure. In this paper we develop estimation procedure for critical point of division the structure change of a time series. Moreover we propose three tests for recognition such specific behavior. The presented methodology is based on the empirical second moment and its main advantage is lack of the distribution assumption. Moreover, the examined statistical properties we express in the language of empirical quantiles of the squared data therefore the methodology is an extension of the approach known from the literature. The theoretical results we confirm by simulations and analysis of real data of turbulent laboratory plasma

Technological and design aspects of the processing of composites and nanocomposites. Volume III

Processing of composites and nanocomposites materials constitutes nowadays an important area of research given the growing interest by these types of materials due to its singular properties, namely in what concerns technological and design aspects. This monography presents the developments taking place in the framework of the NEWEX project during the fourth year of its duration, which is a sequence of other two previous monographies. The main objective of the NEWEX project entitled “Investigation and development of a new generation of machines for the processing of composite and nanocomposites materials” is the exchange of researchers from the institutions participating in the project. Another important objective consists in develop permanent international and inter-sector collaboration between academic research centres (Lublin University of Technology, Technical University of Kosice, University of Minho) and industrial organizations (Zamak-Mercator LLC and SEZ-Krompachy a.s., Dirmeta UAB). The contents of this book reflects the work done within the NEWEX project. It starts by presenting the results obtained concerning new concepts for the extruder parts studied and the manufacturing of those extruder parts. Then, some approaches for modelling and optimizing and to study experimentally the process are described, which includes mixing analysis and monitoring. Finally, a practical and state-of-theart application of the extrusion is identified, namely 3D printing. It is expected that the nine chapters of this monography be useful to the industry of plastics processing and for scientific organisations dealing with technologies and processing of polymer composites and nanocomposites

Zastosowanie rozmytych reguł wnioskowania do automatycznej klasyfikacji zapisów częstości uderzeń serca płodu w odniesieniu do stanu urodzeniowego

Objectives: Fetal monitoring based on the analysis of the fetal heart rate (FHR) signal is the most common method of biophysical assessment of fetal condition during pregnancy and labor. Visual analysis of FHR signals presents a challenge due to a complex shape of the waveforms. Therefore, computer-aided fetal monitoring systems provide a number of parameters that are the result of the quantitative analysis of the registered signals. These parameters are the basis for a qualitative assessment of the fetal condition. The guidelines for the interpretation of FHR provided by FIGO are commonly used in clinical practice. On their basis a weighted fuzzy scoring system was constructed to assess the FHR tracings using the same criteria as those applied by expert clinicians. The effectiveness of the automated classification was evaluated in relation to the fetal outcome assessed by Apgar score. Material and methods: The proposed automated system for fuzzy classification is an extension of the scoring systems used for qualitative evaluation of the FHR tracings. A single fuzzy rule of the system corresponds to a single evaluation principle of a signal parameter derived from the FIGO guidelines. The inputs of the fuzzy system are the values of quantitative parameters of the FHR signal, whereas the system output, which is calculated in the process of fuzzy inference, defines the interpretation of the FHR tracing. The fuzzy evaluation process is a kind of diagnostic test, giving a negative or a positive result that can be compared with the fetal outcome assessment. The present retrospective study included a set of 2124 one-hour antenatal FHR tracings derived from 333 patients, recorded between 24 and 44 weeks of gestation (mean gestational age: 36 weeks). Various approaches for the research data analysis, depending on the method of interpretation of the individual patient-tracing relation, were used in the investigation. The quality of the fuzzy analysis was defined by the number of correct classifications (CC) and the additional index QI – the geometric mean of the sensitivity and specificity values. Results: The effectiveness of the fetal assessment varied, depending on the assumed relation between a patient and a set of her tracings. The approach, based on a common assessment of the whole set of tracings recorded for a single patient, provided the highest quality of automated classification. The best results (CC = 70.9% and QI = 84.0%) confirmed the possibility of predicting the neonatal outcome using the proposed fuzzy system based on the FIGO guidelines. Conclusions: It is possible to enhance the process of the fetal condition assessment with classification of the FHR records through the implementation of the heuristic rules of inference in the fuzzy signal processing algorithms.Cel pracy: Monitorowanie płodu na podstawie analizy sygnału czynności serca płodu (FHR) jest najczęściej stosowaną metodą biofizycznej oceny stanu płodu w czasie ciąży i porodu. Wzrokowa analiza krzywej FHR jest trudna z uwagi na jej złożony kształt. Z tego względu, komputerowo-wspomagane systemy monitorowania stanu płodu dostarczają szeregu parametrów będących rezultatem ilościowej analizy rejestrowanego sygnału. Parametry te są podstawą dla jakościowej oceny stanu płodu. Do najczęściej stosowanych wytycznych, określających sposób interpretacji sygnału FHR należą kryteria określone przez FIGO. Na ich podstawie skonstruowano ważony rozmyty system punktowy, którego zadaniem jest określenie stanu płodu na podstawie kryteriów oceny, jakimi posługuje się ekspert kliniczny. W pracy przedstawiono badania nad zgodnością rozmytej klasyfikacji z oceną stanu płodu wyznaczaną na podstawie punktacji Apgar. Materiał i metody: Proponowany system do automatycznej, rozmytej klasyfikacji stanowi rozwinięcie idei skal punktowych wykorzystywanych do jakościowej oceny zapisów czynności serca płodu. Za pomocą jednej reguły rozmytej modelowana jest zasada oceny pojedynczego parametru opisu ilościowego sygnału FHR zgodnie z wytycznymi FIGO. Wejściami systemu rozmytego są wartości parametrów ilościowych sygnału FHR, a stan wyjścia, wyznaczany w procesie wnioskowania rozmytego, definiuje interpretację zapisu. Proces rozmytej oceny sygnału jest rodzajem testu diagnostycznego, którego wynik, negatywny lub pozytywny, można porównać z oceną stanu urodzeniowego noworodka. Badaniem retrospektywnym objęto zbiór 2124 godzinnych zapisów ciążowych pochodzących od 333 pacjentek, zarejestrowanych pomiędzy 24 a 44 tygodniem ciąży (średni wiek ciążowy to 36 tygodni). W eksperymentach zastosowano różne konstrukcje zbiorów danych, w zależności od przyjętego sposobu interpretacji zbioru sygnałów zarejestrowanych dla pojedynczej pacjentki. Jakość rozmytej analizy automatycznej oceniano na podstawie liczby poprawnych klasyfikacji CC oraz wskaźnika QI będącego średnią geometryczną czułości oraz swoistości. Wyniki: W zależności od przyjętej metody analizy zbioru danych otrzymano różną skuteczność oceny stanu płodu. Podejście, w którym określano jedną wspólną ocenę dla całego zbioru zapisów zarejestrowanych dla pojedynczej pacjentki, pozwoliło na uzyskanie najwyższej jakości automatycznej klasyfikacji. Najlepsze z uzyskanych wyników (CC = 70.9% i QI = 84.0%) potwierdzają możliwość predykcji stanu urodzeniowego płodu na podstawie rozmytego wnioskowania opartego na wytycznych FIGO. Wnioski: Istnieje możliwość wspomagania procesu diagnostyki stanu płodu przez zastosowanie systemu rozmytej klasyfikacji sygnałów FHR, opartego o heurystyczne reguły wnioskowania właściwe doświadczonemu klinicyście

The Use of Untreated Neuburg Siliceous Earth as Filler for High-Density Polyethylene

This paper reports the results of a study on twin-screw direct extrusion run at a screw speed of 120 rev/min to produce a composite pellet product which was used for an injection molding process and after that subjected to static tensile testing as well as hardness and specimen morphology examination. As filler, we used untreated Neuburg siliceous earth (NSE) marketed under trade names Silitin Z86 and Silitin V88 ranging from 10 to 60 wt% in a matrix made of high-density polyethylene (PE-HD) Hostalen GD 7255. The results demonstrate that Young‘s modulus and maximum tensile stress of the polyethylene composite with untreated Neuburg siliceous earth first decrease and then increase with increasing the filler’s content. The addition of Silitin Z86 causes an increase in tensile stress at break while the addition of Silitin V88 leads to its decrease. Strain at maximum tensile stress of the tested molded pieces first increases with increasing the filler’s content, but then starts to decrease. The tested composite molded pieces have lower strain at break as opposed to those without the filler. An increase in the filler’s content leads to an increase in hardness of the tested specimens. The results of specimen morphology demonstrate that the filler is unevenly distributed in the polymer and reveals a strong tendency to agglomerate

Optimization of polymer processing: a review (Part II - Molding technologies)

The application of optimization techniques to improve the performance of polymer processing technologies is of great practical consequence, since it may result in significant savings of materials and energy resources, assist recycling schemes and generate products with better properties. The present review aims at identifying and discussing the most important characteristics of polymer processing optimization problems in terms of the nature of the objective function, optimization algorithm, and process modelling approach that is used to evaluate the solutions and the parameters to optimize. Taking into account the research efforts developed so far, it is shown that several optimization methodologies can be applied to polymer processing with good results, without demanding important computational requirements. Furthermore, within the field of artificial intelligence, several approaches can reach significant success. The first part of this review demonstrated the advantages of the optimization approach in polymer processing, discussed some concepts on multi-objective optimization and reported the application of optimization methodologies to single and twin screw extruders, extrusion dies and calibrators. This second part focuses on injection molding, blow molding and thermoforming technologies.This research was funded by NAWA-Narodowa Agencja Wymiany Akademickiej, under grant PPN/ULM/2020/1/00125 and European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreement No 734205–H2020-MSCA-RISE-2016. The authors also acknowledge the funding by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT (Portuguese Foundation for Science and Technology) under the projects UIDB/05256/2020, UIDP/05256/2020

Modelling the effect of grooved barrels on the performance of single screw extruders

Single screw extruders containing grooved barrels are used in many industrial extrusion lines, for example to manufacture plastics pipes and blown film. Through an increase of the drag friction forces between the polymer and the barrel, the conveying capacity of the screw is enhanced, yielding higher outputs and better process stability. This chapter presents and assesses computationally models for considering the effect of the presence of longitudinal or helical grooves near to the inlet port of the barrel of single screw extruders. The results obtained demonstrate that the existence of grooves clearly improves the performance of the extruder

Optimization of polymer processing: a review (Part I - Extrusion)

Given the global economic and societal importance of the polymer industry, the continuous search for improvements in the various processing techniques is of practical primordial importance. This review evaluates the application of optimization methodologies to the main polymer processing operations. The most important characteristics related to the usage of optimization techniques, such as the nature of the objective function, the type of optimization algorithm, the modelling approach used to evaluate the solutions, and the parameters to optimize, are discussed. The aim is to identify the most important features of an optimization system for polymer processing problems and define the best procedure for each particular practical situation. For this purpose, the state of the art of the optimization methodologies usually employed is first presented, followed by an extensive review of the literature dealing with the major processing techniques, the discussion being completed by considering both the characteristics identified and the available optimization methodologies. This first part of the review focuses on extrusion, namely single and twin-screw extruders, extrusion dies, and calibrators. It is concluded that there is a set of methodologies that can be confidently applied in polymer processing with a very good performance and without the need of demanding computation requirements.This research was funded by NAWA-Narodowa Agencja Wymiany Akademickiej, under grant PPN/ULM/2020/1/00125 and European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie Grant Agreement No 734205–H2020-MSCA-RISE-2016. The authors also acknowledge the funding by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT (Portuguese Foundation for Science and Technology) under the projects UID-B/05256/2020, UID-P/05256/2020

A review on optimization in polymer processing

The use of optimization computational tools is of primordial importance for the polymer processing industry, as they provide the means for improving the efficiency of the process without requiring time-consuming and expensive procedures. This review aims to evaluate the application of optimization methodologies to the most important polymer processing technics, including, single and twin-screw extrusion, dies and calibrators, blow-moulding, injection moulding and thermoforming. The most important features of an optimization system will be identified to identify the best practices for each particular situation. These features include the nature of the objective function (single or multi-objective), the type of optimization algorithm, the modelling routine used to evaluate the solutions and the parameters to be optimized. First, the state-of-the-art optimization methodologies generally employed is presented. This will be followed by a detailed review of the literature dealing with this subject. This will be completed by a discussion taking into account the features referred to above. Therefore, it was possible to show that different optimization techniques can be applied to polymer processing with great success

Multi-objective optimization of single screw polymer extrusion based on artificial intelligence

The performance of the single screw polymer extrusion process depends on the definition of the best set of design variables, including operating conditions and/or geometrical parameters, which can be seen as a multi-objective optimization problem where several objectives and constraints must be satisfied simultaneously. The most efficient way to solve this problem consists in linking a modelling routine with optimization algorithms able to deal with multi-objectives, for example, those based on a population of solutions. This implies that the modelling routine must be run several times, and, thus, the computation time can become expensive, since they are based on the use of sophisticated numerical methods due to the need to obtain reliable results [1]. The aim of this work is to present an alternative based on the use of Artificial Intelligence (AI) techniques in order to reduce the number of modelling evaluations required during the optimization process. This analysis will be based on the use of a data analysis technique, named DAMICORE, able to define important interrelations between all variables related to extrusion and, then, optimize the process [2,3,4]. For that purpose, the results obtained for three practical examples will be presented and discussed. These case studies include the optimization of screw geometrical parameters, barrel grooves section and rotational barrel segment. It will be shown that the results obtained, taking into consideration the design variables, the objectives and the constraints defined, are in agreement with the expected thermomechanical behaviour of the process