https://ph02.tci-thaijo.org/index.php/past/issue/feed Progress in Applied Science and Technology 2022-04-29T22:21:08+07:00 Arranee Chotiko scitechrmutt@rmutt.ac.th Open Journal Systems <p><strong><em>Progress in Applied Science and Technology (PAST)</em></strong>, abbreviation name: <em>Prog Appl Sci Tech</em>; formerly known as<strong> “Science and Technology RMUTT Journal”</strong> (2011- Vo.10 No.1 January-June 2020), is to disseminate knowledge and research in science and technology and to promote research to benefit society.</p> <p><strong>ISSN (Print):</strong> 2730-3012 </p> <p><strong>ISSN (Online): </strong>2730-3020</p> <p><strong>Start year:</strong> 2011</p> <p><strong>Language:</strong> English (since Vol.10 No.2, 2020)</p> <p><strong>Publication fee:</strong> Free of charge</p> <p><strong>Issues per year:</strong> 3 Issues</p> <ul> <li class="show">1<sup>st</sup> issue: January-April</li> <li class="show">2<sup>nd</sup> issue: May-August</li> <li class="show">3<sup>rd</sup> issue: September-December</li> </ul> <p><strong>Index in:</strong> Thai Citation Index Center (TCI) Tier 1</p> https://ph02.tci-thaijo.org/index.php/past/article/view/246030 Surface Modification of Plant-Drive Calotropis Gigantea Fiber Reinforced Polypropylene Composites 2022-02-06T20:59:16+07:00 Haydar Zaman haydarzaman5@gmail.com Ruhul Amin Khan dr.ruhulkhan7@gmail.com <p>In the present study, calotropis gigantea fiber (CGF)/polypropylene (PP) composites with four different weight percentages of CGFs (10, 20, 30, and 40%) were made by compression molding using the film stacking method. The CGF content in the composites was optimized and 40 wt% CGF content exhibited the best mechanical properties. Composites containing 40% of CGF improved tensile modulus and impact strength by 256.2% and 94%, respectively in comparison to virgin PP but achieved 41.8% at 30% CGF content in tensile strength. In our current work, the CGF surface was modified by alkaline treatment (ACGF), and alkaline pretreated CGF was modified with two types of silane coupling agents such as aminopropyltrimethoxy silane (AS) and tetramethoxyorthosilicate (TS) to improve the mechanical performance of PP/CGF composite. For PP/CGF composites, adding silane after alkali pretreatment improves the mechanical properties and subsequently the water absorption of the composites. This tendency has become further noticeable with the growth of CGF content. In this article the maximum mechanical properties of PP/ACGF/TS composites were achieved in 40 wt% CGF content, which showed 19.1% tensile modulus and 67.9% impact strength compared to PP/CGF composites but achieved 24.3% in 30% CGF content in tensile strength. The water absorption test showed that PP/ACGF/TS composites exhibit less water absorption than both PP/ACGF/AS and PP/CGF composites. The CGF surface morphologies and the fractured surfaces of the composites show an improvement in the interfacial CGF-PP adhesion of reinforced composites with alkali-pretreated silane-treated CGFs. The addition of magnesium hydroxide to PP/ACGF/AS and PP/ACGF/TS significantly reduced the horizontal combustion rate. DSC results showed that the addition of AS and TS for CGF resulted in higher crystallization, melting and crystallinity of the composites. The thermal stability of PP/ACGF/TS composite was higher than PP/ACGF/AS and higher than PP/ACGF composite.</p> 2022-04-29T00:00:00+07:00 Copyright (c) 2022 Progress in Applied Science and Technology https://ph02.tci-thaijo.org/index.php/past/article/view/245557 Iteration Methods for a General Variational Inequality System and Common Fixed Point Problems of Nonexpansive Mappings in q-Uniformly Smooth Banach Spaces 2021-12-27T18:13:19+07:00 Uamporn Witthayarat uamporn.wi@up.ac.th Kriengsak Wattanawitoon kriengsak.wat@rmutl.ac.th Phayap Katchang p.katchang@rmutl.ac.th <p>This research proposed the iteration method for finding a common fixed point of an infinite family of nonexpansive mappings and two inverse strongly accretive mappings in -uniformly smooth Banach spaces. Furthermore, our method can also solve a new general variational inequality system and its strong convergence theorem is proved under some appropriate conditions. Our result improves and extends the previous outcomes in the literature.</p> 2022-03-26T00:00:00+07:00 Copyright (c) 2022 Progress in Applied Science and Technology https://ph02.tci-thaijo.org/index.php/past/article/view/246172 On the Diophantine Equation 2/x+3/y+4/z=1/2 2022-03-06T14:30:36+07:00 Kulprapa Srimud kulprapa_s@rmutt.ac.th Nonthiya Makate nonthiya_m@rmutt.ac.th Tawan Ampawa tawan_a@rmutt.ac.th Tadbun Jantree 1161109010107@mail.rmutt.ac.th <p>In this paper, we find all solutions of the Diophantine equation <img title="\frac{2}{x}+\frac{3}{y}+\frac{4}{z}=\frac{1}{2}" src="https://latex.codecogs.com/gif.latex?\frac{2}{x}+\frac{3}{y}+\frac{4}{z}=\frac{1}{2}" /> where <img title="x" src="https://latex.codecogs.com/gif.latex?x" /> , <img title="y" src="https://latex.codecogs.com/gif.latex?y" /> and <img title="z" src="https://latex.codecogs.com/gif.latex?z" /> are positive integers.</p> 2022-04-22T00:00:00+07:00 Copyright (c) 2022 Progress in Applied Science and Technology https://ph02.tci-thaijo.org/index.php/past/article/view/246019 An Observation on the Natural Partial Order of Transformation Semigroups Restricted by an Equivalence Relation 2022-02-04T13:07:30+07:00 Nares Sawatraksa nares.sa@nsru.ac.th Piyaporn Tantong piyaporn.ta@nsru.ac.th <p>Let <img title="T(X)" src="https://latex.codecogs.com/gif.latex?T(X)" /> be the full transformation semigroup of a set <img title="X" src="https://latex.codecogs.com/gif.latex?X" /> . We consider the subsemigroup of <img title="T(X)" src="https://latex.codecogs.com/gif.latex?T(X)" /> defined by <img title="E(X,\sigma)=\{\alpha\in T(X): \forall x,y\in X, (x,y)\in\sigma \;\text{implies}\; x\alpha=y\alpha\}" src="https://latex.codecogs.com/gif.latex?E(X,\sigma)=\{\alpha\in&amp;space;T(X):&amp;space;\forall&amp;space;x,y\in&amp;space;X,&amp;space;(x,y)\in\sigma&amp;space;\;\text{implies}\;&amp;space;x\alpha=y\alpha\}" /> for an arbitrary equivalence relation <img title="\sigma" src="https://latex.codecogs.com/gif.latex?\sigma" /> on <img title="X" src="https://latex.codecogs.com/gif.latex?X" /> . The natural partial order on the largest regular subsemigroup of <img title="E(X,\sigma)" src="https://latex.codecogs.com/gif.latex?E(X,\sigma)" /> is discussed in this paper, and we characterize when two regular elements of <img title="E(X,\sigma)" src="https://latex.codecogs.com/gif.latex?E(X,\sigma)" /> are related under this order. Also, their maximal, minimal and covering elements are described.</p> 2022-04-28T00:00:00+07:00 Copyright (c) 2022 Progress in Applied Science and Technology