Integrated Flow Shop and Vehicle Routing Problem Based on Tabu Search Algorithm

We consider in this paper a m-machine permutation flow shop scheduling problem and vehicle routing problem (VRP) integrated [1]. The manufacturing workshop is a flow shop and there is only one vehicle available. We are interested in the minimization of the total tardiness. related to the delivery completion times. Therefore, we are faced to three interdependent problems: scheduling the jobs in the flow shop environment, batching the completed jobs, and routing the batches. Then, we present the resolution method based on Tabu search and the results that have been obtained. Computational experiments are performed on random data sets and show the efficiency of the methods. Finally, a conclusion and some future research directions are proposed

A microwave active filter for nanosatellite’s receiver front-ends at s-bands

In satellite technology, the communication between space segment and ground segment plays a vital role in the success of the mission. This paper is targeted at study, design and fabrication of a microwave active filter for the receiver front-ends using coupled line filter structure, which can be applied to the nanosatellite’s communication subsystem. The whole active filter module is a combination of a microstrip bandpass filter and a preceding two-stage wideband low noise amplifier using FET devices. The proposed module operates in the frequency range of 2 - 2.4 GHz, which can be divided to 10 frequency slots of about 40 MHz for each. These frequency slots will be used for the S-band multi-frequency receiving function of the ground station, as well as the nanosatellite. The simulated and measured results of this active filter configuration are presented

Design and fabrication of A Ku-band low noise amplifier using FR-4 substrate

The low noise amplifier (LNA) plays an important role in many communication systems, especially at the receiver’s front-ends. In modern RF designs, The LNA is usually fabricated on a microstrip printed circuit board (PCB) due to its simplicity and ability of integrating flexibly with other components in a receiving circuitry unit. At frequencies lower than 6 GHz, the most prevalent substrate material for a microstrip LNA is FR-4 while at higher frequencies of over 10 GHz, it is challenging to design the LNA using this material without causing considerable losses to the RF signal. There are many works related to design microstrip LNA at high frequencies, however, the dielectric substrates used in most of them were high-cost materials for low dielectric loss. This paper introduces an LNA topology using the common, low-cost FR-4 substrate which can be operated in Ku-band for applications such as small satellites’ receivers, with the expected noise figure of lower than 1 dB, gain of around 10 dB and the return loss of around -10 dB. The stepped impedance matching technique has been used for transmission line optimization. The simulated and measured results are presented

Research, design and fabrication of a microwave active filter for nanosatellite’s receiver front-ends at s-band

In satellite technology, the communication between space segment and ground segment plays a vital role in the success of the mission. This paper is targeted at study, design and fabrication of a microwave active filter for the receiver front-ends using coupled line filter structure, which can be applied to the nanosatellite’s communication subsystem. The whole active filter module is a combination of a microstrip bandpass filter and a preceding two-stage wideband low noise amplifier using FET devices. The proposed module operates in the frequency range of 2-2.4 GHz, which can be divided to 10 frequency slots of about 40 MHz for each. These frequency slots will be used for the S-band multi-frequency receiving function of the ground station, as well as the nanosatellite. The simulated and measured results of this active filter configuration are presented

Assessment of earthquake-induced ground liquefaction susceptibility for Hanoi city using geological and geomorphologic characteristics

In this paper, the earthquake-induced liquefaction susceptibility of Hanoi city is assessed using the recent published geological and geomorphologic data. A combination of classification methods based on the distribution of sedimentary deposits proposed by Youd and Perkins (1978) and geomorphologic units proposed by Iwasaki (1982) was applied. The subsurface lithology and geomorphologic maps were combined in a GIS platform for assessing the liquefaction susceptibility of Hanoi city.The resulting map shows that the liquefaction hazard of Hanoi city classified into four categories: high, moderate, low liquefaction potential and not likely areas. In the most of Hanoi area, the ground liquefaction potentials are moderate. The high liquefaction likely areas spread along the river beds and around the lake areas. The not likely and low liquefaction potential areas are observed mainly in the northwest and northeast of the study region such as Chanchim, Soc Son, and Bavi mountains. The present map can help the scientists, engineers, and planners to have the general information on regional liquefaction potential of the Hanoi city. ReferencesBird JF, Bommer JJ, 2004b. Earthquake Losses due to Ground Failure. Submitted to Engineering Geology, 75(2), 147-179.Bird Juliet F, Bommer Julian J., 2004a. Evaluating earthquake losses due to ground failure and identifying their relative contribution (Paper no. 3156). In Proceedings of the 13th world conference on earthquake engineering, Vancouver, B.C., Canada, august 1-6.Bui Van Duan, Nguyen Cong Thang, Nguyen Van Vuong, Pham Dinh Nguyen, 2013. The magnitude of the largest possible earthquake in the Muong La-Bac Yen fault zone. J. Sci. of the Earth, 35(1), 53-59.Dao Dinh Bac, Dang Van Bao, 2010. Geomorphologic characteristics, the ancient river beds system of the capital city and their values to the development of the Thang Long - Hanoi. International Workshop commemorating the 1000 years of Thang Long, Hanoi. Vietnam national University, Hanoi.Ganapathy, G. P., Rajawat, A. S., 2012. Evaluation of liquefaction potential hazard of Chennai city, India: using geological and geomorphological characteristics. Natural hazards, 64(2), 1717-1729.Goyal, A., Sinha, R., Chaudhari, M. and Jaiswal, K., 2001. Performance of Reinforced Concrete Buildings in Ahmedabad during Bhuj Earthquake January 26, 2001. Workshop on Recent Earthquakes of Chamoli and Bhuj: Volume I, Roorkee, India, May 24-26.Iwasaki, T., Tokida, K., Tatsuoka, F., Watanabe, S., Yasuda, S., Sato, H., 1982. Microzonation for soil liquefaction potential using simplified methods. In Proceedings of the 3rd international conference on microzonation, Seattle, 3, 1310-1330.Kuribayashi E., Tatsuoka, F., 1975. Brief review of liquefaction during earthquake in Japan,” Soils and Foundations, 15(4), 81-92.Lew M, Naeim F, Huang SC, Lam HK, Carpenter LD, 2000. Geotechnical and geological effects of the 21 September 1999 Chi-Chi earthquake, Taiwan. Structural Design of Tall Buildings, 9, 89-106.National Research Council, 1985. Ishihara 1985. Liquefaction of Soils During Earthquake, National Academy press, 240, p.34. Nguyen Hong Phuong (Project Manager), 2002. Study of seismic risk of Hanoi city. Project code 01C-04/09-2001-2. Institute for Marine Geology and Geophysics, VAST.Nguyen Hong Phuong (Project Manager), 2007. Application of GIS technology to Development of a model for seismic risk analysis for Hanoi city. Institute for Marine Geology and Geophysics, VAST.Nguyen Hong Phuong (Project Manager), 2014.  Estimation of Site Effects and Assessment of Urban Seismic Risk for Hanoi city. National Scientific Research Project Final report, Institute of Geophysics, VAST.Nguyen Hong Phuong and Pham The Truyen, 2014. Probabilistic seismic hazard assessment for South Central Vietnam. J. Sci. of the Earth, 36(4), 451-461.Phan Trong Trinh, Hoang Quang Vinh, Nguyen Van Huong, Ngo Van Liem, 2013. Active fault segmentation and seismic hazard in Hoa Binh reservoir, Vietnam. Cent. Eur. J. Geosci, 5(2), 223-235.Phan Trong Trinh, Ngo Van Liem, Nguyen Van Huong, Hoang Quang Vinh, Bui Van Thom, Bui Thi Thao, Mai Thanh Tan, Nguyen Hoang, 2012. Late Quaternary tectonics and seismotectonics along the Red River fault zone, North Vietnam. Earth-Science Reviews 114, 224-235.Susumu Yasuda, Nozomu Yoshida, Hiroyoshi Kiku, Hidenori Abo, and Masato Uda, 2001. Analyses of Liquefaction-Induced Deformation of Grounds and Structures by a Simple Method (March 26). International Conferences on Recent Advances in Geotechnical Earthquake Engineering and Soil Dynamics, p.27. http://scholarsmine.mst.edu/icrageesd/04icrageesd/session04/27.Updike, R. G., Egan, J. A., Moriwaki, Y., Idriss, I. M., Moses, T. L., 1988. A model for earthquake-induced translatory landslides in Quaternary sediments. Geological Society of America Bulletin, 100(5), 783-792.Vu Thanh Tam (Project Manager), 2014. Study and propose a reasonable threshold for preventing the subsidence caused by ground water exploitation, pilot application for downtown area of the Hanoi city. Final report of the Scientific research and technology development Project, National Center for water resource planning and investigation. Ministry of Natural Resources and Environment.Youd T. L., 1993. Liquefaction, ground failure and consequent damage during the 22 April 1991 Costa Rica earthquake. Abridged from EERI Proceedings: U.S. Costa Rica Workshop, http://nisee.berkeley.edu/costarica/Youd T. L., and Hoose S.N., 1977.  Liquefaction Susceptibility and Geologic Setting, Proceedings, 6th World Conference on Earthquake Engineering, New Delhi, India, 6, 37-42.Youd T. L., and Perkins D. M., 1978. Mapping liquefaction-induced ground failure potential. Journal of the Geotechnical Engineering Division, ASCE, 104, GT4, 433-446

English teachers’ perception and attitudes of scaffolding method in teaching academic writing: An exploratory study at universities in Vietnam

The primary aim of this research is to investigate the impact of utilizing the scaffolding method on teaching academic writing in the context of English as a Foreign Language (EFL) at universities in Vietnam. This mixed-method study examined the attitudes and perceptions of 88 EFL educators from diverse backgrounds and degree levels who were randomly selected for the research. Methodologically, data were gathered and analyzed using the appropriate methods for each instrument, including a questionnaire and focus group discussion (FGD). Theoretically, the study is a medley of relevant theories and approaches such as Vygotsky’s Sociocultural Theory of Learning, the Scaffolding theory, and the ‘High challenge - High support’ pedagogy. The results of this study suggest that participants used scaffolding to some extent and had strongly positive attitudes and perceptions regarding its practical aspects; however, the findings also revealed that the surveyed lecturers are deficient in the necessary knowledge and skills. In addition, the study's findings imply that EFL teachers need training on how to properly use scaffolding as a pedagogical strategy to facilitate teaching academic writing to EFL students

A Novel Wideband Bandpass Filter using H-shaped DGS

This paper presents a novel compact wide-band bandpass filter (BPF) having good selectivity. It is designed using a dual-plane structure which consists of a parallel-coupled microstrip line on the upper surface and three H-shape defected ground structures (DGS) on the ground plane. By adding three H-shape DGS units on the ground plane, then properly adjusting their dimensions and position, the bandwidth and selectivity of the designed filter can be significantly improved. A compact prototype of wide-band microstrip bandpass filter has been designed, fabricated and measured for the wireless systems applications. The filter exhibits a center frequency at 4.8 GHz, passband from 2.8 GHz to 6.8 GHz with best insertion loss and return loss of 0.8 dB and 40 dB, respectively. The measured results agrees well with the theoretical expectations validating the proposed design

Changes in lesson plans as teachers participate in a professional development on statistical literacy

Research on mathematics teacher knowledge has gained momentum recently; however, research on teacher planning is scarce, especially using lesson plans as the primary data source. This study examines how teachers' lesson plans change as they participate in a professional development, supporting them in implementing the Vietnamese reformed Curriculum 2018. Using a design-based research methodology, we developed a research-informed framework that assesses teachers' lesson plans for developing students' statistical literacy as emphasized in the mathematics Curriculum. Informed by research literature and data collected from teachers, the framework including seven criteria was shared and used by 61 teachers to reflect on the quality of their lessons. The analysis of 38 lesson plans shows all criteria have improved from pre- to post-lesson plans. The teachers included more explicit and comprehensive learning intentions in their post-lessons. Tasks in the post-lesson plans afforded more opportunities for students to develop statistical literacy, helped them engage in the statistical investigation using real data, and included multiple representations. Finally, the post-lesson plans tended to follow the constructivist teaching principles. Implications on ways to develop teachers' planning competence and suggestions for future studies are included. © 2023 Authors