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1

Machinability analysis of thin-walled carbon fiber reinforced ceramic composites based on wire electrical discharge machining

Poroś Dariusz, Wiśniewska Magdalena

Zeszyty Naukowe Politechniki Morskiej w Szczecinie

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2024

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nr 77 (149)

5--13

EN

We propose employing wire electrical discharge machining (WEDM) for shaping thin-walled, multidirectional, carbon fiber reinforced silicon carbide (Cf-SiC) composite parts. Ceramic matrix composite Cf-SiC combines the outstanding mechanical properties of the carbon fiber with oxidation, abrasive wear, corrosion resistance, and high strength at the high temperature of the silicon carbide matrix. The impact of time-related electrical discharge machining parameters (pulse ON-time and break OFF-time) on the material removal rate and surface roughness are analyzed. The material removal rate of the Cf-SiC is proved to be 36% lower than that for machined steel grade 55. The high thermal stresses and interaction of the composite accompanying WEDM are also discussed. Furthermore, an alternative mechanism to the WEDM of metals has been investigated and confirmed by a scanning electron microscopy (SEM) analysis. The morphology of the machined Cf-SiC surface demonstrates the dominance of the carbon fibers’ fracture mechanism, both the transverse and longitudinal forms, with interphase detachment over craters and micro-cracks, pitting, and spalling on the SiC matrix. Satisfactory roughness indicators (Sa = 2 µm) are obtained in 3D topography measurements of the Cf-SiC surfaces. Concluding, the WEDM should be considered a good alternative to Cf-SiC abrasive machining when cutting holes, grooves, keyways, splines, and other complex shapes.

2

The Study Focus on Optimizing Processing Parameters for 3D Printed Composites Using Taguchi

Kumar Girish P. V. R., Devi Devaki K.

Management and Production Engineering Review

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2024

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Vol. 15, No. 3

1--7

EN

The effect of fused filament fabrication (FFF) process parameters on the mechanical properties of 3D-printed carbon fiber (CF)-reinforced recycled polylactic acid (rPLA) composite is presented in this paper. Because they have a significant impact on the mechanical properties of the product layer thickness, raster orientation and infill percentage are the process variables taken into consideration for the studies. The response parameters considered in the study are tensile strength. There is multi-optimisation. Utilizing TOPSIS (Technique for Order Preferences by Similarity to Ideal Solution) analysis to determine the optimal combination of parameters that would yield the greatest strength.

3

Numerical treatment by implementing a successive approximation method for fractional riccati and logistic differential equations

Adel Mohamed, Khader Mohamed M.

Journal of Applied Mathematics and Computational Mechanics

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2024

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Vol. 23, nr 4

5--17

EN

The fractional Riccati/Logistic differential equations (FRDE/FLDE) can be accurately solved numerically by using the approach presented in this study. In the provided questions, the fractional derivative is in the Caputo-Fabrizio (CF) sense. The suggested approach is the successive approximation technique (SAM). In this technique, we approximate the solution of the FRDE and FLDE with a finite-dimensional problem. A particular focus is examining the convergence analysis and estimating the upper bound on the error of the obtained approximate scheme. We offer an outcome on worldwide convergence of consecutive estimates. Also, to show the thoroughness of the method proposed, we computed the residual error function. Illustrative instances are given to prove the usefulness and validity of the suggested method.

4

Effects of Different Fiber Sizes in PLA/Carbon Fiber Composites on Mechanical Properties

Hashim Mohammad Firdaus Abu, Daud Yusrina Mat, Abdullah Mohd Mustafa Al Bakri, Faris Meor Ahmad, Rasidi Mohamad Syahmie Mohamad, Ghazali Che Mohd Ruzaidi, Zainal Farah Farhana, Hasyim Saloma, Nazri N. N. M., Garus Sebastian

Archives of Metallurgy and Materials

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2024

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Vol. 69, iss. 2

723--732

EN

This study assessed the morphology and chemical composition of coir coconut husk carbon fiber, as well as the impact of fiber diameters on the physical and mechanical properties of polylactic acid composites. Researchers are studying polylactide acid, a biodegradable material. This eco-friendly material’s excellent features, generated from sustainable and renewable sources, have drawn many people. Malaysia’s high coconut fiber output made coir husk a popular commodity. Coconut fibers are lignin, cellulose, and hemicellulose. Alkaline treatment eliminates hemicellulose, oil, wax, and other contaminants from coir fibers and removes lignin. Fourier Transform Infrared Spectroscopy and Scanning Electron Microscopy were used to examine the treated coconut fibers’ chemical modification analysis and morphology. Coconut coir husk was carbonized to produce carbon fiber using a furnace operated at 300°C for 2 hours. Fiber and polylactic acid were mixed in different fiber sizes (0,53 μm, 75 μm, and 212 μm) via extrusion and injection processing techniques. The results showed that the alkali treatment reduced the hydroxyl (-OH) group and separated the area from the carbonyl (C=O) group of coconut coir husk, which changed the filler’s hydrophilicity. The fiber size of 212 μm was discovered to have the highest tensile and flexural strength values. According to testing, the modified material structure had a better surface fill-matrix bond. Thus, generalized fiber sizing and characterization methods were developed. Regardless of the matrix, this method can characterize natural fiber strength and interfacial shear strength of varied diameters and solid contents.

5

The Evaluation Effect of Copper Fibre Diameter on Enhancing Compressive Strength of Pure Gypsum

Shubber Arshad Nadhom, Abbas Firas Saeed, Al-Taweel Hayder Mohammed, Ibrahim Sinan Khaleel, Al-Balhawi Ali, Al-Badran Yasir M., Dheyab Layth Sahib, Al-Ridha Ahmed S. D.

Journal of Ecological Engineering

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2023

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Vol. 24, nr 11

148--154

EN

The sustainability and impact of copper fibres on pure gypsum is the primary purpose of this study to investigate a combination of two kinds of copper fibres obtained from environmental waste (damaged electrical wires). The copper fibres are dividings into a fixed length of 10 mm, but with two different diameters: the first is 0.83 mm and the second is 0.63 mm, where the ratio of width to height (L/D) is 12 and 15.9, respectively, with a volume ratio Vf = 0.4%, the ratios 0.5 and 0.6 represent the water to gypsum ratio (W/G ) individually. Each W/G ratio has two types of mixtures which organize according to diameter. The first considers a reference mixture without copper fibres (CF), and the other is a copper fibres mixture. This work found that the compressive strength increased from adding the copper fibres to a mixture of pure gypsum. Furthermore, this increase is apparent in pure gypsum compressive strength when raising the aspect ratio because of reducing the copper fibres’ diameters. In another way, increasing ratio of W/G in the case of existing copper fibres or none may reduce a compressive strength of mixtures. Therefore, when the ratio of W/G drops, the significance of copper fibres may become more apparent.

6

Increasing the operational reliability of a ship by using a composite impeller in the event of hydrophore pump failure

Jabłońska Monika, Jurczak Wojciech, Ozimina Dariusz, Adamiak Marcin

Eksploatacja i Niezawodność

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2023

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Vol. 25, no. 1

art. no. 18

EN

The time-consuming technological process of manufacturing impellers and the high production costs are the reason for the search for alternative materials and manufacturing methods. In this paper, based on a literature analysis, the performance of a pump with an impeller that was manufactured by an incremental method from polyethylene terephthalate with an admixture of glycol and carbon fibre (PETG CF) was selected and studied. Operation tests were conducted on the ship’s rotodynamic pump test bench. The composite impeller pump was shown to have an efficiency at the selected printing parameters of 26,23%, comparable to a tin bronze impeller, which has an efficiency of 27,7%. The maximum pump useful power with the impellers tested was 337 W at a flow rate of 4.42 m3/h. The results confirm that, with a filament layer height of 0.12 mm and 100% fill in the four print contours, the pump characteristics obtained are consistent with those of the reference impeller. This fact ensures continuous operation of the ship’s pump for 48 hours which makes the chosen manufacturing method a reliable emergency method of impeller repair in offshore operations.

7

Effect of silane coating surface treatment on friction and wear properties of carbon fiber/PI composites

Liu Yang, Li Bin, He Yichuan, Dong Yuncheng, Wang Shiguo

Materials Science Poland

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2022

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Vol. 40, No. 2

214--222

EN

PAN-based carbon fiber was surface-modified with silane coating, and a composite material was prepared using a PI resin as a matrix. The structure and surface properties of carbon fibers were studied by means of X-ray photoelectron spectroscopy (XPS) and SEM. The tensile strength of the composite was measured by a tensile tester, and the friction properties of the composite were measured by a micro-nano mechanics comprehensive test system. The results show that treatment with silane coating can improve the surface roughness and chemical activity of carbon fiber, improve the interface between carbon fiber and PI resin matrix, and improve the tensile strength and wear rate of the composite.

8

Comparative Analysis of Procedures and Solutions to Improve Energy Efficiency of Massive MIMO

Phogat Ritu Singh, Joshi Rutvij

International Journal of Electronics and Telecommunications

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2022

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Vol. 68. No. 4

677--686

EN

The blustery growth of high data rate applications leads to more energy consumption in wireless networks to satisfy service quality. Therefore, energy-efficient communications have been paid more attention to limited energy resources and environmentally friendly transmission functioning. Countless publications are present in this domain which focuses on intensifying network energy efficiency for uplink-downlink transmission. It is done either by using linear precoding schemes, by amending the number of antennas per BS, by power control problem formulation, antenna selection schemes, level of hardware impairments, and by considering cell-free (CF) Massive-MIMO. After reviewing these techniques, still there are many barriers to implement them practically. The strategies mentioned in this review show the performance of EE under the schemes as raised above. The chief contribution of this work is the comparative study of how Massive MIMO EE performs under the background of different methods and architectures and the solutions to few problem formulations that affect the EE of network systems. This study will help choose the best criteria to improve EE of Massive MIMO while formulating a newer edition of testing standards. This survey provides the base for interested readers in energy efficient Massive MIMO.

9

Investigation of the Effect of Young’s Modulus on the Contact Strength of Metal Polymer Plain Bearings

Chernets Myron, Pashechko Mykhaylo, Kornienko Anatolii, Borc Jarosław, Zakhariia Roman

Advances in Science and Technology. Research Journal

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2022

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Vol. 16, no. 2

67--73

EN

Using the author's method of research of hybrid (metal-polymer) plain bearings the calculation of their load carrying capacity (contact pressures) is carried out. Studies have been conducted for metal-polymer bearings with a bushing of two types of polymer composites: epoxy based antifriction composite materials DIAMANT Moglice (DIAMANT Metallplastic GmbH) and DK6 (PT) (fillers - graphite, MoS2, Zr). The elastic constants of composite materials, in particular the Young's modulus, have a noticeable effect on the contact pressures in metal-polymer bearings. The Young's modulus is significantly different in these composite materials. In accordance with this factor, the influence of load, bushing diameter and radial clearance on the maximum contact pressures was studied. Quantitative and qualitative regularities of maximum contact pressures from the accepted factors of influence: Young's modulus, loading, bushing diameter, radial clearance, type of bushing material are established. The obtained results are compared with the results obtained by known conventional calculating methods of contact pressures.

10

Equivalent Carbon Dioxide Emission in Useful Energy Generation in the Heat-Generating Plant – Application of the Carbon Footprint Methodology

Chłopek Zdzisław, Lasocki Jakub, Melka Krzysztof, Szczepański Krystian

Journal of Ecological Engineering

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2021

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Vol. 22, nr 2

144--154

EN

The energy sector worldwide is a significant source of air pollutant emission. In Poland, the vast majority of heat and electricity is generated in coal-fired heat and power plants. There is a common belief that high greenhouse gas emissions from the energy sector in Poland are mainly due to the technological processes involving the conversion of energy by burning fossil fuels. However, coal mining also causes a high environmental burden. This paper aimed to determine the carbon footprint of a typical hard coal-fired heating plant in Poland, taking into account mining of hard coal, its transport to the heating plant and useful energy generation in the heating plant. The investigation carried out allowed comparing the process steps and determining which of them is the dominant source of the greenhouse gas emissions. The obtained results show that hard coal mining and hard coal transport account for almost 65% and 5% of total equivalent carbon dioxide emission, respectively. Energy transformations in the heating plant account for 30% of total equivalent carbon dioxide emission, where approx. 29% is due to hard coal burning and 1% due to electricity consumption. The relative shares of carbon dioxide, methane and nitrous oxide in total equivalent carbon dioxide emission account for approx. 91%, 4% and 5%, respectively.

11

Znaczenie sił styku w testach układów scalonych płytek krzemowych. Cz. 1

Dąbrowiecki Krzysztof

Elektronika : konstrukcje, technologie, zastosowania

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2021

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Vol. 62, nr 4

21--25

PL

W części pierwszej artykułu przedstawiono znaczenie siły docisku w kartach wspornikowych jako jednego z najważniejszych parametrów w testowaniu układów scalonych. Zaprezentowano właściwości materiałów używanych do budowy mikrokontaktorów (μkontaktorów) wspornikowych. Omówiono udoskonaloną metodę projektowania μkontaktorów wsporników.

EN

The first part of the article presents the importance of the contact force in cantilever probe cards as one of the most important parameters in the IC testing. Properties of materials used in the construction of cantilever probes (μcontactors) are presented. An improved method of probe designing with the use of the 3D finite element models is discussed.

12

CF–PK–PD analysis of natural hemostatic compounds from Toddalia asiatica (Linn) Lam root bark in rats

Zhang Xiaoyan, Liu Jie, Sun Wenbo, Shen Xiangchun, Gong Xiaojian, Wang Cong, Liang Yan, Zhou Wei

Acta Chromatographica

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2021

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Vol. 33, no. 3

261--269

EN

Natural hemostatic compounds from Toddalia asiatica (Linn) Lam (T. asiatica) root bark had been investigated by a novel strategy, chemical fingerprint–pharmacokinetic–pharmacodynamic (CF–PK–PD) for the first time in this study. The extract sample of T. asiatica root bark was subdivided into petroleum ether (PE), ethyl acetate (EA) and n-butanol (n-B) sample by reagent extraction, EA sample showed significant hemostatic activity using prothrombin time (PT), activated partial thromboplastin time (APTT) and fibrinogen (FIB) as evaluation indexes from rat plasma of PK experiment in hemorrhagic rat model. CF analysis was adopted to assist us to discover six natural compounds from T. asiatica root bark in actual rat plasma after sample treatment by Ultra Performance Liquid Chromatography-Electrospray Ionization (UPLC-ESI) MS, there were only lomatin and 5-methoxy-8-hydroxy psoralen showing significant hemostatic effect (P < 0.05) mainly through endogenous coagulation pathway and fibrinolytic system. In PK–PD study, six compounds in EA sample exhibited relatively rapid absorption and slow elimination characteristics. The mean Tmax and t1/2β of isopimpinellin and pimpinellin were 1.74 and 0.59 h, 5.31 and 6.89 h in rats. On the basis of Sigmoid–Emax model, PK–PD related curves of FIB in hemorrhagic rat model after treatment of T. asiatica root bark were obtained. Predicted Emax, EC50 and ke0 of FIB under isopimpinellin were 4.87 mg/mL, 1.39 μg/mL and 0.81 1/h; predicted Emax, EC50 and ke0 of FIB under pimpinellin were 4.29 mg/mL, 2.47 μg/mL and 0.77 1/h. In conclusion, hemostatic compounds from T. asiatica root bark had been materialized, there were lomatin, isopimpinellin, pimpinellin and 5-methoxy-8-hydroxy psoralen at least as its main active substances through coagulation pathways and fibrinolytic system. CF–PK–PD method as a promising method was worthy of follow-up opening, application in pharmaceutical research.

13

Electrical and thermal characteristics of MWCNTs modified carbon fiber/epoxy composite films

Kareem Aseel A., Rasheed Hussein K.

Materials Science Poland

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2019

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Vol. 37, No. 4

622--627

EN

To enhance interfacial bonding between carbon fibers and epoxy matrix, the carbon fibers have been modified with multiwall carbon nanotubes (MWCNTs) using the dip- coating technique. FT-IR spectrum of the MWCNTs shows a peak at 1640 cm−1 corresponding to the stretching mode of the C=C double bond which forms the framework of the carbon nanotube sidewall. The broad peak at 3430 cm−1 is due to O–H stretching vibration of hydroxyl groups and the peak at 1712 cm−1 corresponds to the carboxylic (C=O) group attached to the carbon fiber. The peaks at 2927 cm−1 and 2862 cm−1 are assigned to C–H stretching vibration of epoxy produced at the defect sites of acid-oxidized carbon fiber surface. SEM image shows a better interface bonding between the fiber and the matrix of modified composites (MWCNTs-CF/Ep) than those of unmodified composite. The loss factor curve of CF-MWCNTs/Ep composites is the narrowest compared with neat epoxy and CF/Ep composites which evinces that the length distribution range of molecular chain segments in the matrix is the narrowest. From the dependence of the AC conductivity on temperature, we can see that σAC increases when temperature increases. The increase in electrical conductivity of the composites may be a result of the increased chain ordering due to annealing effect. The use of MWCNTs to modify the surface of carbon fiber resulted in a large amount of junctions among MWCNT causing an increase in the electrical and thermal conductivity by forming conducting paths in the matrix. The MWCNTs-CF/Ep composite shows better thermal stability than unmodified composites. The strong interaction between CF and MWCNTs can retard diffusion of small molecules from the resin matrix at high temperature and hence, result in the improved thermal stability of the modified CF/Ep composite.

14

Data Mining with Histograms and Domain Knowledge : Case Studies and Considerations

Rauch Jan, Šimůnek Milan

Fundamenta Informaticae

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2019

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Vol. 166, nr 4

349--378

EN

An approach to data mining with histograms is introduced. Several examples of applying data mining for various types of histogram are presented. The problem of filtering out uninteresting histograms is described. It is shown that no suitable, logically correct deduction rules to solve this problem exist. Expert deduction rules are introduced as deduction rules supported by indisputable facts, however, incorrect according to mathematical logic. A method for deciding whether a given expert deduction rule is correct according to a given indisputable fact is developed. Applied examples of correct expert deduction rules are described.

15

Overview of the ship efficiency management plan for a eafaring model ship based on the IMO MEPEC 231 (65) resolution

Waliszyn A., Adamkiewicz A., Yafasov A.

New Trends in Production Engineering

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2018

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Vol. 1, Iss. 1

631-637

EN

The increase of maritime international trade, especially of dangerous liquid cargos led to a significant increase of the number of sea-going ships. Their operation poses a real threat to the maritime environment both as a result of terminal events with transported dangerous liquid cargos and emissions of harmful products from fuels burnt by ship power systems. Because of those there is a need to undertake actions to prevent such occurrences using formal, legal and utilitarian tools. Philosophy of research methodology and rationalization of actions in compliance with international directives have been shown. The article presents the guidelines of the IMO Resolution MEPC 231(65) on preventing air pollution with carbon dioxide from ships. Design Energy Efficiency Index (EEDI) for a new ship was given as well as Energy Efficiency Operational Indicator (EEOI) determined for conventional ships after a completed voyage was defined and interpreted. A model of a Ship Energy Efficiency Management Plan (SEEMP) of a chosen ship has been constructed taking into account possible actions aimed at obtaining the highest power efficiency of the ship at sea voyage. Conclusions have been drawn and possible directions of further actions have been established.

16

Analiza poziomów śladu węglowego dla świata i krajów UE

Kijewska A., Bluszcz A.

Systemy Wspomagania w Inżynierii Produkcji

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2017

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Vol. 6, iss. 2

169--177

PL

Wzrost liczby ludności na świecie i wzrost gospodarek światowych powoduje stały wzrost zapotrzebowania na energię elektryczną. Podstawowymi surowcami do produkcji energii elektrycznej w skali światowej są ropa naftowa, węgiel, gaz oraz energia jądrowa i energia odnawialna. Spalanie paliw kopalnych powoduje emisję gazów cieplarnianych, które w różnym stopniu przyczyniają się do ocieplenia klimatu. Celem artykułu jest analiza śladów węglowych dla świata i krajów UE. Artykuł zawiera charakterystykę pojęcia śladu węglowego, który oznacza całkowitą ilość emisji CO2 i innych gazów cieplarnianych np. metanu czy podtlenku azotu w odniesieniu do emisji wynikającej z cyklu życia produktu, włączając jego składowanie i unieszkodliwianie. Ślad węglowy jest wskaźnikiem ilościowym i uniwersalnym, dającym się policzyć dla przedsiębiorstwa, konkretnego produktu, usługi, procesu, organizacji, kraju bądź regionu. W artykule przedstawiono również analizę porównawczą tego wskaźnika dla różnych krajów na świecie i w UE. Wskazano obliczenia śladu węglowego ogółem oraz w przeliczeniu na osobę, co istotnie różnicuje ocenę gospodarek światowych pod względem wielkości emisji.

EN

The increase in the world population and global economies causes a permanent increase in demand for electricity. The basic fossil fuels for the electricity production in the world are oil, coal, natural gas and other such as: nuclear power and renewable energy. Burning fossil fuels causes greenhouse gas emissions, which contribute in varying degrees to global warming. The aim of the article is to analyze the carbon footprint for the world and for the EU countries. The article contains the characteristics of the concept of the carbon footprint, which is the total amount of CO2 and other greenhouse gases, e.g. methane and nitrous oxide in relation to emissions resulting from the product life cycle, including its storage and disposal. The carbon footprint is quantitative and universal indicator, which can be calculated for the enterprise, a specific product, service, process, organization, country or region. The paper also presents a comparative analysis of this index for different countries in the world and in the EU. Calculations of the carbon footprint in total and per capita are shown which significantly differentiates assessment of world economies in terms of emissions.

17

In-silico evaluation of left ventricular unloading under varying speed continuous flow left ventricular assist device support

Bozkurt S., Bozkurt S.

Biocybernetics and Biomedical Engineering

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2017

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Vol. 37, no. 3

373--387

EN

Continuous flow left ventricular assist device (cf-LVAD) operating speed modulation techniques are proposed to achieve different purposes such as improving arterial pulsatility, aortic valve function or ventricular unloading etc. Although it is possible to improve the left ventricular unloading by modulating the operating speed of a cf-LVAD, it is still unclear what type of pump operating mode should be applied to generate a better left ventricular unloading. This study presents a comparison of different heart pump support modes including constant speed support, copulsative and counterpulsative direct cf-LVAD speed modulation and pump flow rate control to regulate the cf-LVAD operating speed. The simulations were performed using a cardiovascular system model, which consists of active left atrium and ventricle, mitral and aortic valve leaflets, circulatory loop and a cf-LVAD. The cf-LVAD was operated between 7500 rpm and 12,500 rpm with 1000 rpm intervals to simulate constant speed support. The same mean pump operating speeds over a cardiac cycle were applied in the direct operating speed modulation for the copulsative and counterpulsative direct speed modulation cf-LVAD support as in the constant speed support while the same pump-output over a cardiac cycle was applied to drive the pump in flow rate controlled copulsative and counterpulsative cf-LVAD support modes as in the constant speed support. Simulation results show that flow rate controlled counterpulsative pump support mode generates lower end-diastolic left ventricular volume and pressure–volume loop area while generating more physiological left ventricular volume signals over a cardiac cycle with respect to the other pump operating modes.

18

Ślad węglowy jako miernik poziomu emisji gazów cieplarnianych w krajach Unii Europejskiej

Kijewska A., Bluszcz A.

Przegląd Górniczy

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2016

|

T. 72, nr 8

42--45

PL

Dobrobyt społeczeństw i styl życia uzależniony jest od zużycia wysokoenergetycznych paliw kopalnych. Jednakże pociąga to za sobą degradację środowiska, w tym przyczynia się do wzrostu emisji gazów cieplarnianych. Do pomiaru wielkości tej emisji na poziomie narodowym można wykorzystać tzw. ślad węglowy (carbon footprint) mierzony w ekwiwalencie CO2. W pracy przedstawiono analizę emisji gazów cieplarnianych w skali Unii Europejskiej ogółem oraz przypadające na jednego mieszkańca.

EN

Welfare of societies and way of life depends on the consumption of high-energy fossil fuels. However, this entails the degradation of the environment, including contributing to the growth of greenhouse gas emissions. To measure the size of the issue at the national level so called carbon footprint can be used, which is measured in CO2 equivalent. The paper presents an analysis of greenhouse gas emissions in the European Union in general and per capita.

19

Biomonitoring pasywny terenów leśnych w gminie Twardogóra

Marciniak M., Kłos A., Rajfur M.

Proceedings of ECOpole

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2016

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Vol. 10, No. 2

711--720

PL

Celem przeprowadzonych badań była ocena poziomu zanieczyszczenia wybranymi metalami ciężkimi: Zn, Ni, Cd i Pb terenów leśnych gminy Twardogóra. Miasto Twardogóra położone jest w północno-wschodniej części województwa dolnośląskiego, lasy stanowią 44% całej powierzchni gminy. Porosty Hypogymnia physodes oraz mchy Pleurozium schreberi pobrane zostały z 32 miejsc zlokalizowanych w pobliżu wsi Gola, Goszcz, Grabowno Wielkie oraz Sosnówka. Wybrane metale ciężkie (Ni, Zn, Cd i Pb) oznaczono metodą absorpcyjnej spektroskopii atomowej. Wyniki badań zinterpretowano, wykorzystując m.in. współczynnik porównawczy CF, będący różnicą w stężeniach analitu zakumulowanego w porostach i w mchach, odniesioną do jego średniej zawartości w porostach i w mchach. Otrzymane wyniki wskazują na niejednorodną depozycję metali ciężkich na badanym obszarze, szczególnie Zn, Pb i Cd, co potwierdzają m.in. wyznaczone wartości CF. Wykazano, że mchy oraz porosty mogą być ważnym źródłem informacji o zanieczyszczeniu środowiska.

EN

The aim of the study was the assessment of level of contamination with selected heavy metals: Zn, Ni, Cd and Pb of forest areas in Twardogóra commune. The Twardogóra town is located in the north-eastern part of Lower Silesia Province, forests account for 44% of the total area of the commune. Hypogymnia physodes lichens and Pleurozium schreberi moss were collected from 32 sites located near Gola, Goszcz, Grabowno Wielkie and Sosnówka villages. Selected heavy metals (Ni, Zn, Cd and Pb) were determined using atomic absporption spectrometry method. The results were interpreted using, among others, Comparison Factor CF, which is a difference in concentrations of analyte accumulated in lichens and moss, relative to its average content in lichens and moss. The results indicate a non-uniform deposition of heavy metals on the studied area, especially Zn, Pb and Cd, which is confirmed by the designated CF values. It has been shown, that moss and lichens can be an important source of information about environmental contamination.

20

Badanie anizotropii in situ w procesie selektywnego spiekania laserem proszków tworzyw PA12-CF

Zimniak P.

Postępy w Inżynierii Mechanicznej

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2016

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nr 7(4)

33--45

PL

W pracy omówiono podstawy laserowego, selektywnego spiekania proszkowego tworzywa polimerowego jako jednej z wiodących technologii przyrostowego wytwarzania modeli użytkowych i prototypów. Wadą techniki SLS jest zjawisko anizotropii, wynikające z mechanizmu nakładania kolejnych warstw za pomocą narzędzia rozprowadzającego tworzywo proszkowego, kompozytu na bazie poliamidu 12 z dodatkiem włókien węglowych PA12-CF, tj. klingi lub walca, co istotnie wpływa na właściwości mechaniczne uzyskanych wyrobów. W dalszej części pracy opisano unikatowe stanowisko badawcze do nakładania tworzywa proszkowego oraz zaproponowano odpowiednią metodę analizy obrazu, pomocną w zakresie wyznaczenia ukierunkowania włókien tworzywa proszkowego PA12-CF w ujęciu ilościowym i jakościowym.

EN

The grounds of selective laser sintering (SLS) method, as one of the leading methods of rapid prototyping have been discussed in this paper. The greatest disadvantage of SLS method is anisotropy caused by mechanism of laying sequential layers using distributing tool for PA12-CF powder, i.e. a blade or a roller what may considerably influence the mechanical properties of the obtained products. Consequently this paper also describes the unique test stand for laying powdered polymer and presents the convenient method of image analysis which may help in checking behavior of reinforcing fibers in separate layers of PA12-CF polymer in the product regarding qualitative as well as quantitative aspects.