scholarly journals Evaluation of melt quality during polymer extrusion

2021 ◽  
pp. 9-14
Author(s):  
Volodymyr Novodvorskyi ◽  
Mykola Shved ◽  
Dmytro Shved
Keyword(s):  
Statistical Evaluation ◽  
Extrusion Process ◽  
Polymer Materials ◽  
Temperature Uniformity ◽  
Melt Temperature ◽  
Working Bodies ◽  
Industry Sectors ◽  
Potential Use ◽  
Statistical Criteria

Polymer materials are widely spread and used in all industry sectors. The operating properties of polymer products make them practically indispensable in various industries. They have acquired widespread popularity and their production volumes are predicted to grow every year. The extrusion of polymers is one of the main methods for their processing. The melt uniformity is one of the main factors that influence the quality of the products and is determined by the level of mixing, i.e., by the redistribution of additives in a dispersion medium when these additives are introduced into the main polymer. The influence of working conditions, geometry of working bodies and other parameters on the melt temperature uniformity was determined. Nowadays, there are a lot of methods for determining the melt uniformity. They can be used indirectly in or after the extrusion process and can be short or long lasting, which in fact determines the acceptability of each of the methods. To determine the melt uniformity, statistical evaluation methods, which have been verified by many experiments and are well known, are often used. The analysis showed that the mixing index is most sensitive among the criteria described. Although statistical criteria of evaluating the melt uniformity are widespread, it is better to use parameters that allow the state of the mixture to be analyzed directly in the work process for the extrusion of polymers, to identify those that depend on the mixing process. Methods and criteria for verifying the melt quality were analyzed and potential use of their temperature uniformity for measuring and evaluating the melt quality directly in the extrusion process, to eliminate the costly sampling process, was determined.

Interrater reliability of a method to assess hypothalamic involvement in pediatric adamantinomatous craniopharyngioma

2020 ◽  
Vol 25 (1) ◽  
pp. 37-42 ◽  
Author(s):  
Ros Whelan ◽  
Eric Prince ◽  
David M. Mirsky ◽  
Robert Naftel ◽  
Aashim Bhatia ◽  
...  
Keyword(s):  
Quality Of Life ◽  
Brain Tumors ◽  
Interrater Reliability ◽  
Statistical Evaluation ◽  
Grading System ◽  
Reliability Study ◽  
Postoperative Mri ◽  
Mri Scans ◽  
Adamantinomatous Craniopharyngioma

OBJECTIVEPediatric adamantinomatous craniopharyngiomas (ACPs) are histologically benign brain tumors that confer significant neuroendocrine morbidity. Previous studies have demonstrated that injury to the hypothalamus is associated with worsened quality of life and a shorter lifespan. This insight helps many surgeons define the goals of surgery for patients with ACP. Puget and colleagues proposed a 3-tiered preoperative and postoperative grading system based on the degree of hypothalamic involvement identified on MRI. In a prospective cohort from their institution, the authors found that use of the system to guide operative goals was associated with decreased morbidity. To date, however, the Puget system has not been externally validated. Here, the authors present an interrater reliability study that assesses the generalizability of this system for surgeons planning initial operative intervention for children with craniopharyngiomas.METHODSA panel of 6 experts, consisting of pediatric neurosurgeons and pediatric neuroradiologists, graded 30 preoperative and postoperative MRI scans according to the Puget system. Interrater reliability was calculated using Fleiss’ κ and Krippendorff’s α statistics.RESULTSInterrater reliability in the preoperative context demonstrated moderate agreement (κ = 0.50, α = 0.51). Interrater reliability in the postoperative context was 0.27 for both methods of statistical evaluation.CONCLUSIONSInterrater reliability for the system as defined is moderate. Slight refinements of the Puget MRI grading system, such as collapsing the 3 grades into 2, may improve its reliability, making the system more generalizable.

Current Progress in Biomedical Applications of Chitosan-Carbon Nanotube Nanocomposites: A Review

2020 ◽  
Vol 20 (16) ◽  
pp. 1619-1632
Author(s):  
Katarzyna Pieklarz ◽  
Michał Tylman ◽  
Zofia Modrzejewska
Keyword(s):  
Carbon Nanotube ◽  
Medical Science ◽  
Antimicrobial Properties ◽  
Polymer Materials ◽  
Biological Macromolecules ◽  
Medical Sciences ◽  
New Generation ◽  
High Degree ◽  
Dressing Materials

The currently observed development of medical science results from the constant search for innovative solutions to improve the health and quality of life of patients. Particular attention is focused on the design of a new generation of materials with a high degree of biocompatibility and tolerance towards the immune system. In addition, apart from biotolerance, it is important to ensure appropriate mechanical and technological properties of materials intended for intra-body applications. Knowledge of the above parameters becomes the basis for considerations related to the possibilities of choosing the appropriate polymer materials. The researchers' interest, as evidenced by the number of available publications, is attracted by nanobiocomposites based on chitosan and carbon nanotubes, which, due to their properties, enable integration with the tissues of the human body. Nanosystems can be used in many areas of medicine. They constitute an excellent base for use as dressing materials, as they exhibit antimicrobial properties. In addition, they can be carriers of drugs and biological macromolecules and can be used in gene therapy, tissue engineering, and construction of biosensors. For this reason, potential application areas of chitosan-carbon nanotube nanocomposites in medical sciences are presented in this publication, considering the characteristics of the system components.

scholarly journals Assessment of quality of products from polymer materials for machine-building purposes

2020 ◽  
Vol 1614 ◽  
pp. 012044
Author(s):  
D Gramakov ◽  
A Larchenko ◽  
N Filippenko ◽  
A Livshits ◽  
D Bakanin ◽  
...  
Keyword(s):  
Machine Building ◽  
Polymer Materials ◽  
Quality Of Products

scholarly journals Results of Laboratory Studies of the Automated Sorting System for Root and Onion Crops

Agronomy ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1257
Author(s):  
Alexey Dorokhov ◽  
Alexander Aksenov ◽  
Alexey Sibirev ◽  
Nikolay Sazonov ◽  
Maxim Mosyakov ◽  
...  
Keyword(s):  
Control System ◽  
Automatic Control ◽  
Automatic Control System ◽  
Technological Parameters ◽  
Post Harvest ◽  
Manual Sorting ◽  
Sorting System ◽  
Working Bodies ◽  
Automatic Removal

The roller and sieve machines most commonly used in Russia for the post-harvest processing of root and tuber crops and onions have a number of disadvantages, the main one being a decrease in the quality of sorting due to the contamination of working bodies, which increases the quantity of losses during sorting and storage. To obtain high-quality competitive production, it is necessary to combine a number of technological operations during the sorting process, such as dividing the material into classes and fractions by quality and size, as well as identifying and removing damaged products. In order to improve the quality of sorting of root tubers and onions by size, it is necessary to ensure the development of an automatic control system for operating and technological parameters, the use of which will eliminate manual sorting on bulkhead tables in post-harvest processing. To fulfill these conditions, the developed automatic control system must have the ability to identify the material on the sorting surface, taking into account external damage and ensuring the automatic removal of impurities. In this study, the highest sorting accuracy of tubers (of more than 91%) was achieved with a forward speed of 1.2 m/s for the conveyor of the sorting table, with damage to 2.2% of the tubers, which meets the agrotechnical requirements for post-harvest processing. This feature distinguishes the developed device from similar ones.

Quantitative Study on the Effect of Extrusion Process of AZ80 Magnesium Alloy

2010 ◽  
Vol 129-131 ◽  
pp. 1191-1195
Author(s):  
Yan Lou
Keyword(s):  
Set Theory ◽  
Rough Set ◽  
Rough Set Theory ◽  
Extrusion Process ◽  
Average Weight ◽  
Characteristic Parameters ◽  
Billet Temperature ◽  
Az80 Magnesium Alloy ◽  
Ram Speed

By data mining from 3DFEM simulation and Rough Set Theory (RST), it was performed that the extrusion process and die structures effect on the quality of AZ80 magnesium extrudate. The weights of the effect can be obtained. The results show that the effect of the billet temperature on the product quality is dominate, and its average weight is 0.27. The second important parameter is the ram speed and its average weight is 0.22. In addition, it was also found that the effect of the die characteristic parameters on the extrudate is insignificant.

Assessing the quality of budget risk management of the subjects of the Russian Federation

2021 ◽  
Vol 27 (11) ◽  
pp. 2521-2547
Author(s):  
Alena Yu. SUKHOVA
Keyword(s):  
Risk Management ◽  
Russian Federation ◽  
Regional Finance ◽  
Finance Management ◽  
Regional Budget ◽  
Data Source ◽  
The Russian Federation ◽  
Ministry Of Finance ◽  
Statistical Criteria

Subject. The article explores indicators for budget risk management in the subjects of the Russian Federation. Objectives. The aim is to develop a system of indicators to assess the quality of budget risk management, to create a methodology for quality management assessment and test it on the case of 85 subjects, to build a rating for the quality of budget risk management in 2020. Methods. The study rests on creating a model for assessing the quality of budget risk management on the basis of 18 mathematical and statistical criteria and their testing on budget data from 85 federal subjects for 2020, and the deductive approach. Results. I formulated and justified indicators of analysis that demonstrate the level of readiness of the budget of Russian subjects to accept budget risks. The proposed indicators are logically structured into groups and detailed by data source for evaluation. The system of indicators is incorporated into the existing methodology created by the Ministry of Finance of the Russian Federation. The results of the analysis are presented as a rating of subjects of the Russian Federation based on the aggregate assessment of the quality of budget risk management. Conclusions. The offered methodology may serve as a supplement to the methodology for assessing the quality of regional finance management created by the Ministry of Finance of the Russian Federation. It may also help evaluate decisions on proactive risk management and mitigation of consequences of risk events in regional budget utilization.

scholarly journals Investigation on heroin and cocaine quality in Luxembourg

2021 ◽  
Vol 18 (1) ◽  
Author(s):  
Adèle Bourmaud ◽  
Georges Dahm ◽  
François Meys ◽  
Nicolas Gengler ◽  
Alain Origer ◽  
...  
Keyword(s):  
Illicit Drugs ◽  
Statistical Evaluation ◽  
Drug Consumption ◽  
Local Market ◽  
Prevention Strategies ◽  
High Concentration ◽  
Concentration Changes ◽  
Harm Prevention ◽  
Local Levels

Abstract Background Heroin and cocaine are among the most dangerous illicit drugs available and their presence on the market is increasing. These facts have led to the investigation of the quality of heroin and cocaine samples seized in Luxembourg by police and customs but also collected at the national supervised drug consumption facilities. Methods Samples obtained from 2019 to 2020 were analyzed to determine their composition and content using GC–MS, HPLC-UV and LC-Q-ToF. The statistical evaluation of concentration changes depending on the source of collection is based on an ANOVA single factor test and a two-tailed t test. Results Results showed important differences between seizure and collection sources. For both drugs, customs samples had significantly higher concentrations than police samples and the latter had significantly higher concentrations than samples from drug consumption facilities, whereas for heroin two cutting steps were identified, for cocaine samples only one appears to occur on the local market. Indeed, cocaine samples seized by police consisted of a mixture of low and high concentration samples. Conclusion The results show that extensive adulteration with pharmacological active and inactive compounds takes place at local levels, which, however, are different for heroin and cocaine. This knowledge on variability of quality of drugs should be considered in the elaboration of drug and harm prevention strategies.

scholarly journals The effect of foaming agent on mechanical and physical properties of Polypropylene

2018 ◽  
Vol 2 (1) ◽  
Author(s):  
SEDEF CAKIR 1 ◽  
MUHAMMED AYCICEK 1 ◽  
EDIZ ALTUN 2 ◽  
Akin Akinci 1
Keyword(s):  
Mechanical Properties ◽  
Cell Density ◽  
Cell Morphology ◽  
Injection Pressure ◽  
Skin Layer ◽  
Polymer Materials ◽  
Cell Diameter ◽  
Melt Temperature ◽  
Foaming Agent ◽  
Foaming Agents

In this study, Polypropylene (PP) foam materials were used with injection parameters such as melting, molding and injection temperatures. To produce foam materials, chemical foaming agents were used, and added to polymer materials as 1wt.%, 1.5wt.%, 2wt.%, 2.5wt.%, 3wt.%. The mechanical properties of foam samples were determined based on the parameters. Cell morphology characterization such as cell diameter, cell count, skin layer thickness and cell density, and mechanical properties such as tensile and impact strength of polymer foams were examined.Generally, the closed-cell foam structure was obtained. The most important parameters affecting the cell morphology have been injection pressure, melt temperature and amount of foaming agent. With increasing the amount of foaming agent, cell density increased, foam density and mechanical properties decreased.

scholarly journals Evaluation of the suitability of synthetic polymer fuels in self-ignition engines

2019 ◽  
Vol 178 (3) ◽  
pp. 129-134
Author(s):  
Oleh KLYUS ◽  
Paweł KRAUSE ◽  
Vladimir MARKOV ◽  
Anna SKARBEK-ŻABKIN ◽  
Bowen SA
Keyword(s):  
Volume Fraction ◽  
Synthetic Polymer ◽  
Polymer Materials ◽  
Physical Parameters ◽  
Sauter Mean Diameter ◽  
Synthetic Fuels ◽  
Limit Values ◽  
Experimental Part

The article presents a method for determining the quality of spraying a mixture of oil and synthetic fuels obtained from the pro-cessing of polymer materials. Laboratory tests of physical parameters of such a mixture were carried out, which made it possible to determine the limit values for the volume fraction of synthetic fuels. The method of determining the suitability of this type of fuel takes into account the criterion numbers Re and Oh, which include physical parameters such as viscosity, density, and surface tension. The experimental part concerning the distribution of droplets of injected fuel and determination of Sauter Mean Diameter using laser diffrac-tion confirmed the usefulness of the developed method for the assessment of the possibility of using a mixture of petroleum-based and synthetic fuels in self-ignition engines.

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