A study on multi-criteria decision-making in powder mixed electric discharge machining cylindrical shaped parts

In life as well as in engineering, many times, it is necessary to choose the best option among many different options. That will be more difficult when the criteria given for the selection contradict each other. For example, when external cylindrical grinding, the minimum surface roughness requirement necessitates a small depth of cut and feed rate. The material removal rate will be reduced in this case, and this requirement will conflict with the maximum material removal rate requirement. To solve the above problem, a very useful tool is multi-criteria decision-making (MCDM). In this paper, for the first time, MCDM results for powder mixed discharge machining (PMEDM) cylindrical parts of SKD11 tool steel with copper electrodes have been presented. In this work, eighteen experiments with the L18 (16×53) design using the Taguchi method were conducted. Six main input process parameters include the powder concentration, the pulse current, the servo voltage, the pulse on time, and the pulse off time. To select an alternative that simultaneously ensures two criteria including minimum surface roughness (RS) and maximum material removal speed (MRS), four different MCDM methods including MAIRCA (Multi-Attributive Ideal-Real Comparative Analysis), MARCOS (Measurement of Alternatives and Ranking according to Compromise Solution), TOPSIS (Technique for order of preference by similarity to ideal solution), and EAMR (Area-based Method of Ranking) and two methods of criteria weight calculation including MEREC (Method based on the Removal Effects of Criteria) and Entropy methods were selected. The results of MCDM when PMEDM SKD11 tool steel cylindrical parts with two methods for weight determination and four methods for solving MCDM problem were evaluated. In addition, the best alternative to ensure simultaneous minimum RS and maximum MRS was proposed

Universality in odd-even harmonic generation and application in terahertz waveform sampling

Odd-even harmonics emitted from a laser-target system imprint rich, subtle information characterizing the system's dynamical asymmetry, which is desirable to decipher. In this Letter, we discover a simple universal relation between the odd-even harmonics and the asymmetry of the THz-assisted laser-atomic system -- atoms in a fundamental mid-IR laser pulse combined with a THz laser. First, we demonstrate numerically and then analytically formulize the harmonic even-to-odd ratio as a function of the THz electric field, the source of the system's asymmetry. Notably, we suggest a scaling that makes the obtained rule universal, independent of the parameters of both the fundamental pulse and atomic target. This universality facilitates us to propose a general pump-probe scheme for THz waveform sampling from the even-to-odd ratio, measurable within a conventional compact setup

Impact assessment of a local seventeen-year initiative on cassava-based soil conservation measure on sloping land as a climate-smart agriculture practice in Van Yen District, Yen Bai Province, Vietnam

Van Yen District in Yen Bai Province represents the general terrain conditions and farming systems of the northern mountainous region of Vietnam. It has suffered land degradation due to soil erosion and nutrient depletion, which in turn led to declined crop yield, and food insecurity. The district experienced these impacts due to unsustainable upland agricultural practices. The Department of Agriculture and Rural Development realized that their previous practices would not leave anything behind for the next generations. This prompted them to launch an agricultural conservation program in 2003 to restore degraded soils, which would improve the production in the farms, and diversify incomes and the household economy of local farmers. Over the 17 years of implementation, the program has introduced six conservation measures that have been well-received and implemented by the farmers of Van Yen. This report assesses the impacts of the 17-year program using the economic, environmental, and social lenses with a focus on the cassava crop, considering the traditional cassava monocrop system (or non-adoption group) and the six conservation measures (or adoption group). The study applied a mixed-methods approach, using semi-questionnaire to collect qualitative information from 488 farmers across six communes and surveys to collect soil samples to assess the levels of soil restoration among certain measures. The study also used the quantitative research findings from two other research studies conducted in Mau Dong Commune to help discuss its findings

Conservation agriculture for a climate-resilient and sustainable upland agriculture: A success story from a seventeen-year local program in northern Vietnam

The brief elaborates on the lessons learned from an impact assessment of a local seventeen-year initiative on cassava-based soil conservation measure on sloping land as a climate-smart agriculture practice in Van Yen District, Yen Bai Province, Vietnam. Focusing on the economic, environmental, and social benefits, the recommendations push for institutional level strategies on how this success story can be replicated in areas with similar biophysical and socio-economic conditions

CAMELLIA SINENSIS VAR. MADOENSIS (SECT. THEA, THEACEAE), A NEW TAXON FROM VIETNAM

Camellia sinensis var. madoensis is described and illustrated as a new variety of Camellia sinensis (section Thea, Theaceae) from Xuan Loc Commune, Song Cau District, Phu Yen Province. The new variety is easily distinguishable from C. sinensis var. sinensis by style free ½ to the base. The ITS sequence of this variety is also different from that of Camellia sinensis and its other varieties, while the matK gene sequences are nearly identical among Camellia taxa

Outcome and impact assessment of the Climate-Smart Village Program in Northern Vietnam

Yen Bai province inherits representative biophysical, socio-economic, smaller-holder farming characteristics to economic marginalization and climatic risks and impacts to agricultural production and local livelihoods of Vietnam’s northern mountain region (NMR). The CCAFS project deployed to Ma Climate-Smart Village (CSV) in Yen Bai in 2015 with bilateral funding support from two other research projects aimed at setting up a demonstration-for-scaling example of a rural community equipped with capacities for enhanced climate adaptation and resilience. This study applied a three tier interview data collection methodology (key informant interviews – focus group discussions – indepth farmer interviews) to thoroughly investigate 120 households about six main outcomes accomplished by the project up until 2021. The project has achieved great outcomes from the village to the provincial levels. However, the project work still has a potential to be scaled to the National Target Program on New Rural Development (NTM) given its interest in developing resilient communities in climate-vulnerable regions across the country applying the CSV approach in its 2021-2025 strategy. Despite the closing of the CCAFS program by December 2021, this most important scaling pathway will be continued by the VIBE 2018.05 (funded by the Irish Aid) and COALESCE/2020/34 (funded by the Irish Research Council) under the management of Vietnam National University of Agriculture – a long-term strategic partner of the CCAFS program in the NRM

CAMELLIA SINENSIS VAR. MADOENSIS (SECT. THEA, THEACEAE), A NEW TAXON FROM VIETNAM

Camellia sinensis var. madoensis is described and illustrated as a new variety of Camellia sinensis (section Thea, Theaceae) from Xuan Loc Commune, Song Cau District, Phu Yen Province. The new variety is easily distinguishable from C. sinensis var. sinensis by style free ½ to the base. The ITS sequence of this variety is also different from that of Camellia sinensis and its other varieties, while the matK gene sequences are nearly identical among Camellia taxa.Camellia sinensis var. madoensis được mô tả và minh họa với vai trò là một thứ mới của Camellia sinensis (section Thea, Theaceae) ghi nhận tại xã Xuân Lộc, huyện Sông Cầu, tỉnh Phú Yên. Thứ mới này có thể dễ dàng phân biệt với C. sinensis var. sinensis bởi vòi nhụy rời ½ tính từ đế. Trình tự ITS của thứ này cũng khác với Camellia sinensis và các thứ khác của nó

Scaling the Climate-Smart Village model in national-level programs: The recommendations for adoption in the implementation of the Nông Thôn Mới (Vietnam’s National Target Program on New Rural Development) 2021-2030 Strategy

The New Rural Development Program or Nông Thôn Mới (NTM) is a national target program of Vietnam that has enabled 57% of rural communes to achieve the NTM status, which aims to raise the socio-economic standard of living of small communities while facilitating agricultural development. Agricultural development is threatened by the impacts of climate change, which carries high risk for an agriculture-dependent country like Vietnam. This Info Note discusses how the Climate-Smart Village (CSV) model can be applied in the NTM to help the communities under this program achieve “advanced” and “demonstration” status based on 19 criteria. Recommendations were listed on how to integrate the CSV model into the NTM

A formal proof of the Kepler conjecture

This article describes a formal proof of the Kepler conjecture on dense sphere packings in a combination of the HOL Light and Isabelle proof assistants. This paper constitutes the official published account of the now completed Flyspeck project