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Selective Recovery of Palladium from Used Aqua Regia by Hollow Fiber Supported with Liquid Membrane
Weerawat, Patthaveekongka,Nattaphol, Vijitchalermpong,Ura, Pancharoen 한국화학공학회 2003 Korean Journal of Chemical Engineering Vol.20 No.6
This research study way aimed at recovering palladium from used aqua regia by means of a hollow fiber thoroughly supported with liquid membrane. The liquid membrane, consisting of two extractants--thioridazine HCl and oleic acid-solubilized in chloroform-was used to coat the micropomus hollow fiber throughout. Sodium nitrite, a stripping agent, which was fed through the shell side, flowed counter-currently with the feed solution fed via the tube side. The following factors were investigated the concentrations of the two extractants and of s&um nitrite, the pH of used aqua regia, the flow rates of both the feed and stripping solution, and the number of mns in the hollow fiher module. It was found that after a 30-minute operation, 29.10% of palladium ion was optimally recovered at 0.0005-M thioridazine and 0.05-M oleic acid. With reference to the precious metals recovered, the following order was recorded Pd(Ⅱ)>Pt(Ⅳ)>Cu(Ⅱ)>Au(Ⅲ). It was observed that synergistic extraction could be gained at the concentration level of the extractants, regulated in the experiment. The liquid membrane system had long-term stability and even after the third run, it could still recover palladium up to 65%.
Bounmy Khaminsou,Chatthai Thaiprayoon,Weerawat Sudsutad,Sayooj Aby Jose 경남대학교 기초과학연구소 2021 Nonlinear Functional Analysis and Applications Vol.26 No.1
In this paper, we investigate existence, uniqueness and four different types of Ulam’s stability, that is, Ulam-Hyers stability, generalized Ulam-Hyers stability, Ulam-Hyers- Rassias stability and generalized Ulam-Hyers-Rassias stability of the solution for a class of nonlinear fractional Pantograph differential equation in term of a proportional Caputo fractional derivative with mixed nonlocal conditions. We construct sufficient conditions for the existence and uniqueness of solutions by utilizing well-known classical fixed point theorems such as Banach contraction principle, Leray-Schauder nonlinear alternative and Krasnosel’ski ̆i’s fixed point theorem. Finally, two examples are also given to point out the applicability of our main results.
Comparison of Workload Perception for Original and Modified Cognitive Tasks
Shuxun Chi,Manida Swangnetr Neubert,Orawan Buranruk,Weerawat Limroongreungrat,Wichai Eungpinichpong,Rungthip Puntumetakul 대한산업공학회 2019 Industrial Engineeering & Management Systems Vol.18 No.4
Memory search performance is commonly required in many daily life and professional careers. Sternberg MemorySearch Task (MST) is originally designed to test working memory (WM) retrieval function. However, in differentscenarios, memorizing a string of letters (i.e., stimulus items in original (MST) may not be able to represent the realtask characteristics, in this case for a specific soccer player population. Therefore, a modified MST was designedbased on literature review and interview with soccer players. With the same numbers of WM requirements with theoriginal MST, the modified MST was designed to adopt numeric (player numbers) and color codes (team uniform) asstimuli. The objective of this study was to preliminarily compare subjective workload perception during the originaland modified MST performance. Seven healthy male university students (average age of 30.7±8.0 years) were recruited to participate in this study. All participants were asked to perform both the original and modified MST including low and high workload intensity conditions. All subjective workload scores were collected by using NASA-TaskLoad Index (NASA-TLX). In general, the results showed increase in workload intensity to induce higher workloadperception for both test conditions. Mental Demands and Effort contributed as major demanding components of thiscognitive task type. Although overall workload of both tests was comparable, subscale workload scores of the modified MST found to be lower than the original MST. The findings suggested that the modified MST can be used to testsimilar demanding workload component target, as compared with the original MST. However, since different types ofsymbolic information posed different levels of mental workload perception, the task stimuli should be carefully designed to represent actual characteristics of the task of interest.