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Tytuł:
Positive bilinear discrete-time systems with delays
Dodatnie biliniowe układy dyskretne z opóźnieniami
Autorzy:
Kaczorek, T.
Nguyen, A. D.
Powiązania:
https://bibliotekanauki.pl/articles/153400.pdf
Data publikacji:
2006
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
biliniowość
sterowalność
opóźnienie
dodatni układ dyskretny
bilinear system
controllability
delay
discrete-time
positive system
Opis:
Necessary and sufficient conditions are established for the positivity of bilinear discrete-time systems with delays. Solutions to positive bilinear discrete-time systems are derived. The controllability to zero of the bilinear positive systems with delays is addressed. Necessary and sufficient conditions for the controllability to zero of positive bilinear systems with delays are formulated and proved. The considerations are illustrated by examples.
Podano warunki konieczne i wystarczające dodatności biliniowych układów dyskretnych z opóźnieniami w wektorze stanu i w wymuszeniu. Podano również metodę wyznaczania rozwiązania tych biliniowych układów dyskretnych z opóźnieniami. Wyprowadzono warunki konieczne i wystarczające sterowalności do zera tej klasy układów dodatnich. Rozwiązanie ogólne zostało zilustrowane przykładem liczbowym.
Źródło:
Pomiary Automatyka Kontrola; 2006, R. 52, nr 10, 10; 75-78
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Gaze-J2K: gaze-influenced image coding using eye trackers and JPEG 2000
Autorzy:
Nguyen, A.
Chandran, V.
Sridharan, S.
Powiązania:
https://bibliotekanauki.pl/articles/309070.pdf
Data publikacji:
2006
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
eye tracking
image compression
importance map
JPEG 2000
region of interest
Opis:
The use of visual content in applications of the digital computer has increased dramatically with the advent of the Internet and world wide web. Image coding standards such as JPEG 2000 have been developed to provide scalable and progressive compression of imagery. Advances in image and video analysis are also making human-computer interaction multi-modal rather than through the use of a keyboard or mouse. An eye tracker is an example input device that can be used by an application that displays visual content to adapt to the viewer. Many features are required of the format to facilitate this adaptation, and some are already part of image coding standards such as JPEG 2000. This paper presents a system incorporating the use of eye tracking and JPEG 2000, called Gaze-J2K, to allow a customised encoding of an image by using a user's gaze pattern. The gaze pattern is used to automatically determine and assign importance to fixated regions in an image, and subsequently constrain the encoding of the image to these regions.
Źródło:
Journal of Telecommunications and Information Technology; 2006, 1; 3-10
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Software Startups – A Research Agenda
Autorzy:
Unterkalmsteiner, M.
Abrahamsson, P.
Wang, X. F.
Nguyen-Duc, A.
Shah, S.
Bajwa, S. S.
Baltes, G. H.
Conboy, K.
Cullina, E.
Dennehy, D.
Edison, H.
Fernandez-Sanchez, C
Garbajosa, J.
Gorschek, T.
Klotins, E.
Hokkanen, L.
Kon, F.
Lunesu, I.
Marchesi, M.
Morgan, L.
Oivo, M.
Selig, C.
Seppänen, P.
Sweetman, R.
Tyrväinen, P.
Ungerer, C.
Yagüe, A.
Powiązania:
https://bibliotekanauki.pl/articles/953060.pdf
Data publikacji:
2016
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
software startup
research agenda
software-intensive systems
Opis:
Software startup companies develop innovative, software-intensive products within limited time frames and with few resources, searching for sustainable and scalable business models. Software startups are quite distinct from traditional mature software companies, but also from micro-, small-, and medium-sized enterprises, introducing new challenges relevant for software engineering research. This paper’s research agenda focuses on software engineering in startups, identifying, in particular, 70+ research questions in the areas of supporting startup engineering activities, startup evolution models and patterns, ecosystems and innovation hubs, human aspects in software startups, applying startup concepts in non-startup environments, and methodologies and theories for startup research. We connect and motivate this research agenda with past studies in software startup research, while pointing out possible future directions. While all authors of this research agenda have their main background in Software Engineering or Computer Science, their interestin software startups broadens the perspective to the challenges, but also to the opportunities that emerge from multi-disciplinary research. Our audience is therefore primarily software engineering researchers, even though we aim at stimulating collaborations and research that crosses disciplinary boundaries. We believe that with this research agenda we cover a wide spectrum of the software startup industry current needs.
Źródło:
e-Informatica Software Engineering Journal; 2016, 10, 1; 89-123
1897-7979
Pojawia się w:
e-Informatica Software Engineering Journal
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A simulation of integral and derivative of the solution of a stochastici integral equation
Autorzy:
Nguyen, Hy
Nguyen, Minh
Powiązania:
https://bibliotekanauki.pl/articles/1312064.pdf
Data publikacji:
1992
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Opis:
A stochastic integral equation corresponding to a probability space $(Ω,Σ_ω,P_ω)$ is considered. This equation plays the role of a dynamical system in many problems of stochastic control with the control variable $u(·):ℝ^1 → ℝ^m$. One constructs stochastic processes $η^{(1)}(t)$, $η^{(2)}(t)$ connected with a Markov chain and with the space $(Ω,Σ_ω,P_ω)$. The expected values of $η^{(i)}(t)$ (i = 1,2) are respectively the expected value of an integral representation of a solution x(t) of the equation and that of its derivative $x'_u(t)$.
Źródło:
Annales Polonici Mathematici; 1992, 57, 1; 1-12
0066-2216
Pojawia się w:
Annales Polonici Mathematici
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An improvement of a hydraulic self-climbing formwork
Autorzy:
Nguyen, Van Tinh
Nguyen, Kiem Anh
Nguyen, Van Linh
Powiązania:
https://bibliotekanauki.pl/articles/139495.pdf
Data publikacji:
2019
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
climbing formwork
self-climbing formwork
hydraulic self-climbing formwork
Opis:
Nowadays, self-climbing formworks are commonly used in the construction of concrete buildings with a great height, such as high-rise buildings, silos, and bridge piers. A regular formwork can be improved to have more functions, e.g., the formwork itself can climb to the desired construction site. Climbing characteristics of the formwork as well as opening and closing characteristics of the formwork shell are essential criteria for evaluating the performance of a self-climbing formwork. The effective ones were mentioned in different studies, where most of them were published in patents of countries, e.g., the United States and China. Dissimilar from these studies, this paper presents several improvements for some certain groups to enhance the features of a hydraulic self-climbing formwork. Based on the analysis of the composition and the working principle of the actual climbing formwork types, a new opening and closing method of the formwork shells and a new rail clamping device are suggested. They are applied to design a self-climbing formwork with the shell’s working size of 4 m × 3 m. Their load capacity, as well as the flatness of the concrete surface after casting, are assessed. The proposed solutions can result in various advantages, e.g., the shorter initial alignment time, the increase of the quality concrete surface, and the maximal automation for construction operations.
Źródło:
Archive of Mechanical Engineering; 2019, LXVI, 4; 495-507
0004-0738
Pojawia się w:
Archive of Mechanical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A note on the Hasse principle
Autorzy:
Nguyen, Thang
Powiązania:
https://bibliotekanauki.pl/articles/1392255.pdf
Data publikacji:
1990
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Źródło:
Acta Arithmetica; 1989-1990, 54, 3; 171-184
0065-1036
Pojawia się w:
Acta Arithmetica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A remark on Nilsson type integrals
Autorzy:
Minh, Nguyen
Ziemian, Bogdan
Powiązania:
https://bibliotekanauki.pl/articles/1359520.pdf
Data publikacji:
1996
Wydawca:
Polska Akademia Nauk. Instytut Matematyczny PAN
Opis:
We investigate ramification properties with respect to parameters of integrals (distributions) of a class of singular functions over an unbounded cycle which may intersect the singularities of the integrand. We generalize the classical result of Nilsson dealing with the case where the cycle is bounded and contained in the set of holomorphy of the integrand. Such problems arise naturally in the study of exponential representation at infinity of solutions to certain PDE's (see [Z]).
Źródło:
Banach Center Publications; 1996, 33, 1; 277-285
0137-6934
Pojawia się w:
Banach Center Publications
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
The contribution of geophysics to archaeology: a case study of an ancient canal of the Oc Eo culture in the Mekong Delta, Vietnam
Autorzy:
Le, Ngoc Thanh
Nguyen, Quang Dung
Nguyen, Quang Bac
Nguyen, Quang Mien
Nguyen, Dan Vu
Duong, Ba Man
Nguyen, Dinh Chau
Powiązania:
https://bibliotekanauki.pl/articles/184367.pdf
Data publikacji:
2019
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
electromagnetic profiling
electrical resistivity tomography
hand-auger
radiocarbon dating
ancient canal
alluvial deposits
Oc Eo culture
Ba The mountain
Opis:
Generally, underground ancient canals are infilled with alluvial materials, with the canal bed and substrate often having different resistivity values. This study aimed to determine the location and morphology of Malleret’s ancient canal 16 located to the southeast of the Ba The mountain, Mekong Delta, Vietnam by means of geophysical techniques. Two geophysical methods were used: electromagnetic profile and electric resisitivity tomography. A geoelectric structure 70 m long with 70–95 mS/m of apparent conductivity was found. On the electrical resistivity tomography section, a resistivity zone of 10–20 Ω∙m, 1–4 m deep, 70 m wide corresponds to the mentioned above geoelectric structure, which is in an asymmetric U-shape extending toward the southeastern bank of canal 16. Hand-augering confirmed that the canal bed is fully incised into Holocene sediments as a substrate which stretches down to the Pleistocene. The sediments are composed of loams mixed with plant remains with a resistivity ρ ~ 10–15 Ω∙m. Both of the canal banks at a depth of 5 m are made up of Holocene sedi-ments (ρ ~ 4–10 Ω∙m). The 14C measurements determined the age of the organic matter in the canal as being equal to 1210 ±85 BP, suggesting canal 16 ceased being operational at that time. The precise positioning of canal 16 on the ground surface, as well as identifying the morphology of the canal bed, were corroborated by geophysical techniques. The obtained results are of considerable value to archaeologists.
Źródło:
Geology, Geophysics and Environment; 2019, 45, 1; 45-56
2299-8004
2353-0790
Pojawia się w:
Geology, Geophysics and Environment
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A Solution to Ensure Ventilation when Expanding the Area of Cam Thanh Underground Coal Mine, Ha Long Coal Company, Vietnam
Autorzy:
Nguyen, Cao Khai
Nguyen, Van Tinh
Nguyen, Phi Hung
Nguyen, Van Quang
Powiązania:
https://bibliotekanauki.pl/articles/2020950.pdf
Data publikacji:
2021
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
mine ventilation
mine ventilation and safety
Cam Thanh mines area
ventilation system adjustment
fan operating points
kopalnie
wentylacja
Wietnam
Opis:
In the process of underground mining, the mining system changes for various reasons. One of the main reasons is changes in the mining production plans, especially the scales and outputs. Nowadays, coal mines in Vietnam have been expanding in width and depth, and so have the mines’ ventilation systems. Consequently, there will be changes in the alteration of the structure of the design ventilation system, which reduces the effectiveness of the ventilation and does not meet the main objective of mine ventilation, directly affect the safety of the working environment in the mine. Therefore, it is necessary to research the improvement of the ventilation system with the development and specific conditions of underground coal mines in Vietnam, improving the efficiency of the ventilation work and assuring the safety of the mine environment. Cam Thanh coal mine, Ha Long coal company, Vietnam, is the case study for this research. The article considers the plan of increases the mining output by more than 1.5 times, propose solutions to improve the ventilation system accordingly, helping the company proactively implement the production plan, ensure the working environment's safety, and reduce the costs of mine ventilation.
Źródło:
Inżynieria Mineralna; 2021, 2; 533--542
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Parametric model analysis, geometrical characteristics and tool trajectories to surface roughness when machining the cycloid screw by a five-axis milling machine
Autorzy:
Pham, Van Bong
Thien, Nguyen Van
Nguyen, Van Que
Duy, Trinh Nguyen
Nguyen, Duy Khanh
Tien, Dung Hoang
Powiązania:
https://bibliotekanauki.pl/articles/2086278.pdf
Data publikacji:
2022
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
cycloid screw surface
five axis milling machine
ball nose end mill
surface roughness
Opis:
To improve the screw machining accuracy in modern air compressors. This paper investigates three main issues during the development process for cycloid screw machining methods on five-axis CNC machine tools with high precision and efficiency. First, the theoretical basis of cycloid screw surface shaping and derivative of the final profile equation is established. Then, modeling the center trajectory and feed rate according to the cycloid screw profile is given. Next is the experimental setup and simulation of the cycloid screw machining process and discussions. The obtained surface quality prediction parameters are close to the actual measured value, which can be used as a reference model for five-axis CNC milling technology processes. All experimental results obtained by the proposed mathematical model show that a surface with good surface quality is created, meeting the requirements for surface quality. The main work can be used as references for engineers and technicians in practice.
Źródło:
Journal of Machine Engineering; 2022, 22, 2; 108--124
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Luminescence Spectra of ZnAl$\text{}_{2}$O$\text{}_{4}$:Cr$\text{}^{3+}$ Spinel Nanopowders
Autorzy:
Luc, H. H.
Nguyen, T. K.
Nguyen, V. M.
Suchocki, A.
Kamińska, A.
Le, V. K.
Nguyen, V. H.
Luong, T. T.
Powiązania:
https://bibliotekanauki.pl/articles/2037040.pdf
Data publikacji:
2003-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
78.60.-b
72.80.Ga
81.05.Je
81.05.Mh
Opis:
The synthetic ZnAl$\text{}_{2}$O$\text{}_{4}$ spinels doped with Cr$\text{}^{3+}$ ions are prepared from ZnSO$\text{}_{4}$, Al$\text{}_{2}$(SO$\text{}_{4}$)$\text{}_{3}$, and Cr$\text{}_{2}$(SO$\text{}_{4}$)$\text{}_{3}$. The spinel single phase is detected from X-ray diffraction. Luminescence properties of Cr$\text{}^{3+}$ in ZnAl$\text{}_{2}$O$\text{}_{4}$ were studied by low temperature luminescence and decay measurements. Four luminescence lines at 14570, 14520, 14460, and 14330 cm$\text{}^{-1}$ were found to originate from structure distortion and the line at 14175 cm$\text{}^{-1}$ - from chromium pairs. The broad emission band at about 13540 cm$\text{}^{-1}$ is considered to arise from a new Cr$\text{}^{3+}$ center in ZnCr$\text{}_{2}$O$\text{}_{4}$.
Źródło:
Acta Physica Polonica A; 2003, 104, 6; 581-587
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Effectiveness of a Mobile Application-Based Intervention to Improve Knowledge and Practice Regarding Silicosis Among High-Risk Workers of Dust Exposure in a Northern Province of Vietnam
Autorzy:
Nguyen, Thi Thu Huyen
Ta, Thi Kim Nhung
Pham, Thi Quan
Nguyen, Thanh Thao
Nguyen, Ngoc Anh
Nguyen, Thi Lien Huong
Le, Thi Huong
Luong, Mai Anh
Le, Thi Thanh Xuan
Powiązania:
https://bibliotekanauki.pl/articles/27323251.pdf
Data publikacji:
2023
Wydawca:
Polskie Towarzystwo Przeróbki Kopalin
Tematy:
knowledge
practice
workers
silicosis
mobile application
effectiveness
praca
aplikacja mobilna
Wietnam
Opis:
Objectives: to analyze changes in knowledge and practices regarding silicosis in groups of workers at high risk of silicosis before - after an intervention. Methods: The study was conducted from 2018 to 2019 based on structured questions related to knowledge and practices of silicosis of workers directly exposed to silica dust in a Northern province of Vietnam. The mobile app-based intervention was applied to steel workers, then compared with ironworkers in improvements in silicosis knowledge and practices. Results: Significant changes in the intervention group related to workers' knowledge about the signs suggestive of silicosis, disease consequences, measures to reduce the risk of silicosis, and participation in annual occupational disease examinations were reported. Conclusion: Mobile applicationbased interventions could improve silicosis knowledge and practice among workers at high risk of exposure to silica dust.
Źródło:
Inżynieria Mineralna; 2023, 2; 295--302
1640-4920
Pojawia się w:
Inżynieria Mineralna
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A solution for increasing data rate of Doppler-RAKE system
Autorzy:
Nguyen Nguyen, M.
Modelski, J.
Powiązania:
https://bibliotekanauki.pl/articles/307797.pdf
Data publikacji:
2003
Wydawca:
Instytut Łączności - Państwowy Instytut Badawczy
Tematy:
diversity
Doppler-RAKE
CDMA
multi-path
fast-fading
spread-time signaling
multi-user detection
channel coding
Opis:
Doppler-RAKE detection in the CDMA system has been further developed and offers better performances in comparison to conventional RAKE detection, especially in fast-fading environments. Also, the multi-user Doppler-RAKE system works more effectively with channel coding applications. However, by means of exploring the Doppler effect, the system's data rate is decreased. We propose a simple solution to increase the data rate for the system while keeping the Doppler gain.
Źródło:
Journal of Telecommunications and Information Technology; 2003, 3; 130-134
1509-4553
1899-8852
Pojawia się w:
Journal of Telecommunications and Information Technology
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Water Lettuce (Pistia stratiotes L.) as a Potential Material for Biogas Production
Autorzy:
Cong, Nguyen Van
Thanh, Tran Van
Kha, Le Thi Mong
Hoang, Nguyen Xuan
Powiązania:
https://bibliotekanauki.pl/articles/2105278.pdf
Data publikacji:
2022
Wydawca:
Polskie Towarzystwo Inżynierii Ekologicznej
Tematy:
water lettuce
anaerobic digestion
renewable energy
Opis:
This study evaluated the biogas production potential of water lettuce (Pistia stratiotes L.) by batch anaerobic digestion under in-vitro conditions. Twenty-one litre-plastic jars were used to conduct 4 replications over 75 days. The results showed that solution temperature, pH and Eh were suitable for biogas production. More than 50% of the obtained CH4 was formed within 17–42 days after incubation. The maximum daily CH4 production was 0.052 L/gVS, whilst the daily H2S concentration was low, with a maximum value of 28 ppm within 14–21 d after incubation. Moreover, the peak of daily biogas production was seen at day 16 with production of 0.12 L/gVS. The results highlight that water lettuce biomass can be potentially used to produce high quality biogas in anaerobic incubation.
Źródło:
Journal of Ecological Engineering; 2022, 23, 6; 182--188
2299-8993
Pojawia się w:
Journal of Ecological Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Modular intelligent fixture system for flexible clamping of large parts
Autorzy:
Möhring, H.-C.
Gessler, W.
König, A.
Nguyen, L. T.
Nguyen, Q. P.
Powiązania:
https://bibliotekanauki.pl/articles/100187.pdf
Data publikacji:
2017
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
machine tool
modular fixture
hybrid material
intelligent system
Opis:
In this work a modular intelligent fixture system for flexible clamping of large parts is presented. The fixture modules consist of a hybrid material structure involving metal frame elements and mineral casting. These modules can be combined and connected to realize fixtures adapted to the geometry of the workpiece and requirements of the machining processes. By integrated pipes and interfaces, an internal hydraulic supply and active cooling is possible even for combined modules. Temperature and acceleration sensors allow for an active thermal control and process monitoring. The modules and first test fixtures are investigated in experiments.
Źródło:
Journal of Machine Engineering; 2017, 17, 4; 29-39
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Difference in flotation behavior of galena by single and multi-step chronoamperometric oxidation
Autorzy:
Ozdemir, Orhan
Hampton, Marc A
Nguyen, Tuan
Nguyen, Anh
Powiązania:
https://bibliotekanauki.pl/articles/110510.pdf
Data publikacji:
2019
Wydawca:
Politechnika Wrocławska. Oficyna Wydawnicza Politechniki Wrocławskiej
Tematy:
surface roughness
hydrophobicity
contact angle
elemental sulfur
galena
chronoamperometry
Opis:
The relationship between electrochemical oxidation (Chronoamperometry) of galena surfaces and collocterless galena flotation was investigated in detail. The chronoamperometry (CA) micro- flotation experiments and zeta potential experiments were performed with ground galena particles (106×53 μm). In addition, contact angle measurements were carried out with a freshly cleaved galena sample at pH 4 in order to investigate any changes in galena surface hydrophobicity after the surface oxidation electrochemically. The results from this study indicated that there is a strong link between the nano/micro-physico-chemical properties of a sulphide on galena surfaces and collectorless flotation of galena particles at pH 4. The results were also supported with the electrokinetics behavior and contact angle values of galena particles.
Źródło:
Physicochemical Problems of Mineral Processing; 2019, 55, 3; 812-821
1643-1049
2084-4735
Pojawia się w:
Physicochemical Problems of Mineral Processing
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A hybridization of machine learning and NSGA-II for multi-objective optimization of surface roughness and cutting force in AISI 4340 alloy steel turning
Autorzy:
Nguyen, Anh-Tu
Nguyen, Van-Hai
Le, Tien-Thinh
Nguyen, Nhu-Tung
Powiązania:
https://bibliotekanauki.pl/articles/2200263.pdf
Data publikacji:
2023
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
multi-objective optimisation
machine learning
AISI 4340
NSGA-II
ANN
Opis:
This work focuses on optimizing process parameters in turning AISI 4340 alloy steel. A hybridization of Machine Learning (ML) algorithms and a Non-Dominated Sorting Genetic Algorithm (NSGA-II) is applied to find the Pareto solution. The objective functions are a simultaneous minimum of average surface roughness (Ra) and cutting force under the cutting parameter constraints of cutting speed, feed rate, depth of cut, and tool nose radius in a range of 50–375 m/min, 0.02–0.25 mm/rev, 0.1–1.5 mm, and 0.4–0.8 mm, respectively. The present study uses five ML models – namely SVR, CAT, RFR, GBR, and ANN – to predict Ra and cutting force. Results indicate that ANN offers the best predictive performance in respect of all accuracy metrics: root-mean-squared-error (RMSE), mean-absolute-error (MAE), and coefficient of determination (R2). In addition, a hybridization of NSGA-II and ANN is implemented to find the optimal solutions for machining parameters, which lie on the Pareto front. The results of this multi-objective optimization indicate that Ra lies in a range between 1.032 and 1.048 μm, and cutting force was found to range between 7.981 and 8.277 kgf for the five selected Pareto solutions. In the set of non-dominated keys, none of the individual solutions is superior to any of the others, so it is the manufacturer's decision which dataset to select. Results summarize the value range in the Pareto solutions generated by NSGA-II: cutting speeds between 72.92 and 75.11 m/min, a feed rate of 0.02 mm/rev, a depth of cut between 0.62 and 0.79 mm, and a tool nose radius of 0.4 mm, are recommended. Following that, experimental validations were finally conducted to verify the optimization procedure.
Źródło:
Journal of Machine Engineering; 2023, 23, 1; 133--153
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A new environmentally friendly chemical mechanical polishing method applied for surface finishing Ti-6Al-4V alloy
Autorzy:
Quang, Nguyen Minh
Quan, Nguyen Ngoc
Mai, Nguyen Trong
Thanh, Le Thi Phuong
Tung, Nguyen Tien
Tan, Tran Ngoc
Hai, Ha Thanh
Trinh, Nguyen Duy
Powiązania:
https://bibliotekanauki.pl/articles/28407325.pdf
Data publikacji:
2023
Wydawca:
Wrocławska Rada Federacji Stowarzyszeń Naukowo-Technicznych
Tematy:
chemical-mechanical polishing
hydrogen peroxide
TI-6AL-4V
silica
malic acid
Opis:
A new eco-friendly slurry has been developed for the chemical mechanical polishing process with a solution of malic acid, deionized water, and an oxidizing agent hydrogen peroxide (H2O2). The surface quality of Ti-6Al-4V workpieces with the proposed chemical mechanical polishing slurry with optimal parameters include oxidizers (H2O2), colloidal (SiO2) slurry, and deionized water by weight 8%, 45%, and 47% respectively, the pH concentration is adjusted 4 through the malic acid content present in the slurry. Experimental results obtained with the proposed chemical mechanical polishing method show a more improved surface quality than previous studies when applying for polishing Ti-6Al-4V alloy. The developed chemical mechanical polishing method's polishing results under optimal conditions obtain an ultra-fine surface quality with Ra = 0.696 nm over a measuring area of 53×70 μm2. X-ray photoelectron (XPS) and electrochemical measurements were used to study the chemical reaction mechanisms in the proposed chemical mechanical polishing process. The chemical mechanical polishing processes for the surface of the Ti-6Al-4V alloy workpiece with the H2O2 oxidizing agent showed high suitability with the reactants formed on the surface such as Ti, V, and Al oxide. With the proposed oxidant and the established chemical mechanical polishing slurry, the feasibility and surface quality of the super smooth Ti-6Al-4V workpiece formed after polishing were demonstrated. The established chemical mechanical polishing method shows high applicability in environmental protection and Ti-6Al-4V alloy ultra-precision machining industries.
Źródło:
Journal of Machine Engineering; 2023, 23, 4; 64--76
1895-7595
2391-8071
Pojawia się w:
Journal of Machine Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Thermal-mechanical coupled simulation
Autorzy:
Nguyen, H. P.
Derewońko, A.
Niezgoda, T.
Powiązania:
https://bibliotekanauki.pl/articles/244229.pdf
Data publikacji:
2015
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
thermo-mechanical coupled
simulation
plastic deformation
Opis:
Optimal design of engineering structures and technological processes requires taking into account various factors affecting the state of strain and stresses in the structure. Coupled thermo-mechanical analysis enables, among others, determination of undesirable changes in a body shape resulting from the implementation method of the initially-boundary conditions, for example, time-varying load and physical properties of the material depending on the temperature. They are also used to determine residual stresses remaining after manufacturing to prevent revalued stiffness and rigidity of the designed construction. In this study, coupled thermo-mechanical analysis illustrated by metal machining operation is presented. The commercial code MSC.Marc has been used to develop a coupled thermo-mechanical finite element model of plane-stress orthogonal metal cutting operations. Metal cutting is one of the most important and common manufacturing processes in the car industry. A thermal mechanical transient analysis is performed to convert mechanical work into heat by plastic deformation of the workpiece material and friction during metal machining operation. The finite element mesh distortion, due to large deformations, requires a remesh technique. The influence of parameters of the 2D and 3D finite element mesh adaptation on plastic deformation and temperature generated in the cutting processing is considered.
Źródło:
Journal of KONES; 2015, 22, 3; 161-168
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-25 z 140

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