http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
- 中文 을 입력하시려면 zhongwen을 입력하시고 space를누르시면됩니다.
- 北京 을 입력하시려면 beijing을 입력하시고 space를 누르시면 됩니다.
RISS 인기검색어
- 검색키워드
- 저자 : Dahaghin, Zohreh (검색결과 4 건)
- 무료
- 기관 내 무료
- 유료
-
-
Abkenar, Shiva Dehghan,Hosseini, Morteza,Dahaghin, Zohreh,Salavati-Niasari, Masoud,Jamali, Mohammad Reza Korean Chemical Society 2010 Bulletin of the Korean Chemical Society Vol.31 No.10
A novel method was developed for the speciation of chromium in natural water samples based on homogeneous liquid-liquid extraction and determination by flame atomic absorption spectrometry (FAAS). In this method, Cr(III) reacts with a new Schiff's base ligand to form the hydrophobic complex, which is subsequently entrapped in the sediment phase, whereas Cr(VI) remained in aqueous phase. The Cr(VI) assay is based on its reduction to Cr(III) by the addition of sodium sulfite to the sample solution. Thus, separation of Cr(III) and Cr(VI) could be realized. Homogeneous liquid-liquid extraction based on the pH-independent phase-separation process was investigated using a ternary solvent system (water-tetrabutylammonium ion ($TBA^+$)-chloroform) for the preconcentration of chromium. The phase separation phenomenon occurred by an ion-pair formation of TBA and perchlorate ion. Then sedimented phase was separated using a $100\;{\mu}L$ micro-syringe and diluted to 1.0 mL with ethanol. The sample was introduced into the flame by conventional aspiration. After the optimization of complexation and extraction conditions such as pH = 9.5, [ligand] = $1.0{\times}10^{-4}\;M$, [$TBA^+$] = $2.0{\times}10^{-2}\;M$, [$CHCl_3$] = $100.0\;{\mu}L$ and [$ClO_4$] = $2.0{\times}10{-2}\;M$, a preconcentration factor (Va/Vs) of 100 was obtained for only 10 mL of the sample. The relative standard deviation was 2.8% (n = 10). The limit of detection was sufficiently low and lie at ppb level. The proposed method was applied for the extraction and determination of chromium in natural water samples with satisfactory results.
-
Towards optimal slip force and stiffness distribution in designing friction dampers
Pourya Sam-Daliri,Seyed Mehdi Zahrai,Hamid Dahaghin 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.79 No.3
The considerable capacity of friction dampers in energy dissipation makes them a good choice for vibration control of structures. The slip force of friction dampers and also the stiffness of the corresponding bracing system are the major parameters that must be chosen carefully in the design procedure of these dampers. This paper presents an innovative approach to determine these parameters using the data extracted from a series of analyses conducted on three different structures, subjected to five different earthquake records. For this purpose, 900 time-history analyses are conducted. The responses extracted from these analyses are used to compare the effect of different slip forces and to choose the optimum case. Also, a stiffness calibration method is proposed to determine the bracing system stiffness. Finally, two multi-functional optimization methods are introduced to find a single value for optimal slip force. It is shown that between 56 to 74% of the input energy can be dissipated by friction dampers, using this design approach. Additionally, up to 20, 45, 64, and 62% reductions in maximum displacement, velocity, acceleration, and base shear are achieved respectively for the structures studied in this research.
-
Shiva Dehghan Abkenar,Morteza Hosseini,Zohreh Dahaghin,Masoud Salavati-Niasari,Mohammad Reza Jamali 대한화학회 2010 Bulletin of the Korean Chemical Society Vol.31 No.10
A novel method was developed for the speciation of chromium in natural water samples based on homogeneous liquid-liquid extraction and determination by flame atomic absorption spectrometry (FAAS). In this method, Cr(III)reacts with a new Schiff's base ligand to form the hydrophobic complex, which is subsequently entrapped in the sediment phase, whereas Cr(VI) remained in aqueous phase. The Cr(VI) assay is based on its reduction to Cr(III) by the addition of sodium sulfite to the sample solution. Thus, separation of Cr(III) and Cr(VI) could be realized. Homogeneous liquid-liquid extraction based on the pH-independent phase-separation process was investigated using a ternary solvent system (water-tetrabutylammonium ion (TBA+)-chloroform) for the preconcentration of chromium. The phase separation phenomenon occurred by an ion-pair formation of TBA and perchlorate ion. Then sedimented phase was separated using a 100 μL micro-syringe and diluted to 1.0 mL with ethanol. The sample was introduced into the flame by conventional aspiration. After the optimization of complexation and extraction conditions such as pH = 9.5, [ligand] = 1.0 × 10‒4 M, [TBA+] = 2.0 × 10‒2 M, [CHCl3] = 100.0 μL and [ClO4‒] = 2.0 × 10‒2 M, a preconcentration factor (Va/Vs) of 100 was obtained for only 10 mL of the sample. The relative standard deviation was 2.8% (n = 10). The limit of detection was sufficiently low and lie at ppb level. The proposed method was applied for the extraction and determination of chromium in natural water samples with satisfactory results.
연관 검색어 추천
이 검색어로 많이 본 자료
활용도 높은 자료
