MODELING AND SIMULATION OF A LEAN SYSTEM. CASE STUDY OF A PAINT LINE IN A FURNITURE COMPANY

Since they were first developed, lean methodologies have grown in importance and scope and have been applied in both manufacturing and service. However, determining how to transform a common manufacturing company into a lean one, as well as how to evaluate the future company, are challenges for both researchers and manufacturers. This paper presents a case study of a lean manufacturing implementation for the paint line system in a furniture company. A systematic method for execution is shown. In addition, a simulation model is constructed to evaluate the new system in comparison with the MRP system. The new system promises much improvement in terms of a resource’s utility and the system’s productivity.Lean Techniques, Simulation Model, Paint Line, Furniture Company.

Fine-grained Concrete Mix Design using Statistical Methods for Ultra-thin Whitetopping Overlay Application

Whitetopping is a thin layer structure covering on an existing asphalt pavement to improve resistance to rutting and increase the durability road surface. This thin layer usually made of concrete without coarse aggregate, is used mainly to repair the old damaged asphalt road surface without altering its texture. Due to the high longevity, using this type of concrete for reinforcing and repairing roads in unfavorable climatic conditions as in Vietnam brings technical, economic, environmental effective, and suitable with the trend of sustainable development. This article shows results on mix design of high performance fine - grained concrete used for thin whitetopping overlays from materials available in Vietnam by using statistical methods. The Design Expert 11.0 software was used to evaluate the influence and relationship between the influencing variables such as the ratio Water/Binder and the Sand/Binder ratio and concrete strength through the regression equation determination by experimental planning method. After checking the compatibility, the maximum value of the compressive strength and optimum mix design were found through solving this mathematical model. The concrete with optiumum proportion has good workability, high abrasion resistance; its compressive strength develops rapidly at early age and achieves more than 100MPa at 28 days. Using this Fine-grained concrete will help increasing durability and reduce the maintenance cost in the future

Multiscale investigation of the behavior of heart valve interstitial cells in response to pathological shape and mechanical stimulation

Our works aim to provide an insight into how aortic valve interstitial cells (VICs) respond to pathological shape and mechanical stimulation as well as the potential signaling pathway that mediates these responses, using a multiscale approach. A single cell model was developed to investigate the effect of altered shape on valve cell function as valve cells were reported to significantly deform during the cardiac cycle. Single VICs were controlled to take on features with different width-to-length aspect ratios that corresponded to the steady-state shapes adopted by VICs when stretched to 0%, 10% and 20%, respectively. It appeared that single VIC reorganized their cytoskeleton and increased cellular activities, including contractility, metabolism, proliferation and pathological activation, in response to shape alterations. This study provided a fundamental understanding of VIC behavior at single cell level. In order to further examine valve cell pathophysiology, a more physiologically-relevant 3-dimensional (3D) stretchable model was developed to better simulate natural heart valve environment. We developed and characterized a collagen-based scaffold for dynamic culture of heart VICs. This 3D scaffold was porous, biocompatible and mechanically robust. For this reason, it was utilized as a culture model for the subsequent cell signaling study where the role of fibroblast growth factor on valve cell biology was examined in the presence of mechanical stretching stimulation. Stretch magnitudes of 10% and 20% were used to mimic healthy and pathological conditions, respectively. We reported that the Akt/mTOR pathway was up-regulated at elevated 20% stretch which was associated with increased cell proliferation/metabolism. Treatment with fibroblast growth factor 1/ fibroblast growth factor 2 (FGF1/FGF2) significantly altered cellular responses such that they aided in cell proliferation at 10% stretch while reduced cell proliferation at 20% stretch. FGF1/FGF2 treatment was also able to reduce expression of activated markers in pathologically stretched cells, suggesting that FGF1/FGF2 signaling might be a potential target for drug therapies for heart valve treatment. Overall, this project provided a specific picture of how heart valve cells responded to pathological stimulations at multiscale levels and the involvement of FGF-receptor signaling. It is hoped that the knowledge gained from these studies could help to identify therapeutic targets for valvular disease treatment

EFFECTS OF SPEAKER\u27S ACCENT IN A MULTIMEDIA TUTORIAL ON NON-NATIVE STUDENTS\u27 LEARNING AND ATTITUDES

Research in the field of multimedia has yielded principles for the design of effective multimedia instructional messages including Mayer\u27s principles regarding voice. According to the voice principle, students learn more deeply when the narration in a multimedia lesson is spoken by a native voice rather than a non-native voice. The generalizability of the voice principle has been demonstrated when applied to multimedia users who are native speakers of the language used in narration. However, three out of four English users are non-native speakers of English, and the vast majority of verbal exchanges in English do not involve any native speakers of the language at all. By focusing on non-native users, the results of this study should clarify the applicability of the voice principle to a broader target audience. The study investigated whether the accent of the narrator in a multimedia tutorial affected participants\u27 learning and attitudes toward the narrator. The independent variable of the study was narrator\u27s accent with two levels: native accent and non-native shared accent. The dependent variables of the study were participants\u27 learning and their attitudes toward the narrators. Sixty-five Chinese participants at a Midwestern university in the United States were randomly assigned to one of two groups in this experimental design. Data to test the dependent variables were collected through a learning achievement test and an attitude survey. Data analyses revealed that there was no significant difference in overall learning and recall level learning between the two accent groups. However, the group who heard the narration spoken with the native American English accent had significantly more positive attitudes toward their respective narrator than the group who heard the narration spoken with a non-native shared Chinese accent. The study qualifies the voice principle by establishing the limits of its generalizability to non-native English speakers. The study suggests to instructional designers that the use of a non-native shared accent should not affect students\u27 learning negatively although it may affect their attitudes toward the speakers. In addition, the study helps assure non-native instructors that they can record their own voices to use in multimedia instruction as their non-native students will learn as effectively as with a native English accent

Very high cycle fatigue of copper: Evolution, morphology and locations of surface slip markings

The surfaces of commercially pure polycrystalline copper specimens subjected to interrupted 20 kHz fatigue tests in the very high cycle fatigue regime were investigated. The stress amplitude needed to form the early slip markings was found twice lower than the stress amplitude required to fracture which confirmed the results obtained by Stanzl-Tschegg et al. (2007). Three types of slip markings were classified according to their morphology and their location in the polycrystalline material. They are compared to slip markings observed during fatigue tests at frequencies lower than 100 Hz and numbers of cycles lower than 107. For 20 kHz fatigue tests, stress amplitudes ranging from 45 MPa to 65 MPa produce straight and long early persistent slip markings located along twin boundaries. Stress amplitudes lower than 45 MPa produce clusters of fine early persistent slip markings mainly located at triple junctions

NAVIGATION STRATEGY FOR MOBILE ROBOT BASED ON COMPUTER VISION AND YOLOV5 NETWORK IN THE UNKNOWN ENVIRONMENT

Intelligent mobile robots must possess the ability to navigate in complex environments. The field of mobile robot navigation is continuously evolving, with various technologies being developed. Deep learning has gained attention from researchers, and numerous navigation models utilizing deep learning have been proposed. In this study, the YOLOv5 model is utilized to identify objects to aid the mobile robot in determining movement conditions. However, the limitation of deep learning models being trained on insufficient data, leading to inaccurate recognition in unforeseen scenarios, is addressed by introducing an innovative computer vision technology that detects lanes in real-time. Combining the deep learning model with computer vision technology, the robot can identify different types of objects, allowing it to estimate distance and adjust speed accordingly. Additionally, the paper investigates the recognition reliability in varying light intensities. The findings of this study offer promising directions for future breakthroughs in mobile robot navigatio

THE EFFECTS OF THINK-ALOUD STRATEGY ON EFL YOUNG LEARNERS’ READING SKILL PRACTICE

Think-aloud is described as a strategy in which students verbalize their thoughts while they read. This strategy is used to help students monitor their own thinking and comprehend the text. This current study aimed to examine the effects of the think-aloud strategy on EFL young learners’ reading skill practice and identify their attitudes towards the think-aloud strategy used by the teacher in teaching at a foreign language center in Can Tho city (Southern Vietnam’s Mekong Delta region). This study was experimental research using both quantitative and qualitative approaches. The quantitative approach was used to investigate the effects of the think-aloud strategy on young learners’ reading skill practice while the qualitative data was collected to understand the young learners’ attitudes towards the use of the think-aloud strategy in teaching and learning reading skills. Pre-test, post-test, and semi-structured interviews were used to collect the data. The study was conducted with one group of participants. The participants included 25 students who were at the age of 10-12 years old. The results from the pre-test and post-test showed that there was a significant difference in the students‘ reading comprehension performance after the intervention. Thus, the think-aloud strategy has a great impact on the improvement of students’ reading comprehension. Besides, there was no difference in reading comprehension achievement between males and females before and after the treatment. Especially, the results from the semi-structured interview revealed that all students had positive attitudes towards the think-aloud strategy.  Article visualizations

Eco-friendly Super Sulphated Cement Concrete Using Vietnam Phosphogypsum and Sodium Carbonate Na2CO3

Sustainable development is one of the critical topics in the construction industry today, especially in reducing CO2 emissions and production energy costs. There have been many studies worldwide on using ground granulated blast furnace slag combined with phosphogypsum (PG) to replace binder (B) in making concrete. However, this topic in Vietnam has not received much attention despite the large backlog of phosphogypsum waste. One of the main disadvantages limiting the feasibility of super-sulphated binders in concrete is the relatively slow hydration and hardening processes, which affect the rate of strength development of mortar and concrete, especially at an early age. In this study, the use of Na2CO3 salt as a quick, solid additive can overcome the disadvantages of this type of binder. Research results show that using 15 to 25% phosphorus gypsum waste (PG) and a combination of 60 to 80% finely granulated blast furnace slag (GGBFS) with a small amount of cement and an activator like Na2CO3can replace cement in making concrete. The concrete mix has good workability, and the maximum compressive strength after 28 days can reach over 50 MPa. Using industrial wastes as the main ingredients to make binders will improve sustainable development, reducing environmental pollution and the cost of mortar and concrete products in construction. Doi: 10.28991/CEJ-2022-08-11-06 Full Text: PD