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Designing and experimental study of compact vibration isolator with quasi-zero stiffness
Anvar Valeev,Radmir Tashbulatov,Boris Mastobaev 국제구조공학회 2021 Structural Engineering and Mechanics, An Int'l Jou Vol.79 No.4
This study aimed to develop a compact high-efficiency vibration isolator. It was proposed to use force characteristic with quasi-zero stiffness. To avoid a number of design problems, the isolator was designed in a dome shape. This study features a mathematical model of the vibration isolator with quasi-zero stiffness. It allows calculating the isolator properties by geometrical parameters. Stability analysis giving advanced formulas for achieving the maximum workload at certain dimensions was made. For an experimental study, the prototypes were made of shock-absorbing rubbers IRP1346, IRP1347, IRP1348, and fluoroelastomer SKF-32. Force characteristic in static condition was studied, which showed the high efficiency of the compact vibration isolator with quasi-zero stiffness: natural frequency equals 0.8-1.2 Hz. An experimental study in dynamic condition was done using load cell sensors to measure dynamic force transmitted with and without the vibration isolator. The experiment shows a vibration isolation coefficient equal to 244, corresponding to the natural vibration frequency of 2.17 Hz. The study shows the vibration isolator with quasi-zero stiffness as highly efficient, compact, and very perspective for industrial application.
Electro-Physical Properties of a Si-Based MIS Structure with a Low-bftextitk SiOC(-H) Film
Anvar Zakirov,Chi Kyu Choi,An Soo Jung,rangaswamy Navamathavan,Seung Hyun Kim,Yong Jun Jang 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.3
SiOC(-H) films with low dielectric constants have been prepared by using plasma enhanced chemical vapor deposition with a mixture of methyltriethoxysilane and oxygen precursors. The C-V characteristics of the structures, Al/SiOC(-H)/p-Si(100), were studied in the forward and the reverse directions by applying a polarizing potential. We found that the ratio of the maximum to the minimum capacitance (Cmax/Cmin) depended on the [MTES/(MTES+O2)] flow rate ratio. Annealed samples exhibited even greater reductions of the maximum capacitance and the dielectric constant of the SiOC(-H) samples. After annealing at 400 C, the measurement in the reverse direction revealed an interesting behavior in the form of strongly pronounced “steps.” The bonds between Si-O and the -CH3 group reduced the surface charge density, and the distribution of the surface charge density depended on [MTES/(MTES+O2)] flow rate ratio and the annealing temperature because the fixed positive (Si-CH3)+ and negative (Si-O)− changed the configuration at the SiOC(- H)/p-Si(100) interface. The SiOC(-H) film had donor (O2) and acceptor (Si-CH3 -groups) levels, and the electronic process at the SiOC(-H)/p-Si(100) interface was defined by the (Si-CH3)+ and the (Si-O)− bonds.
( Anvar Amouzmehr ),( Behrouz Dastar ),( Jalil Ghassemi Nejad ),( Kyung Il Sung ),( Jayant Lohakare ),( Fereidom Forghani ) 한국동물자원과학회 ( 구 한국축산학회 ) 2012 한국축산학회지 Vol.54 No.3
A total of 800 one-day-old chickens(Cobb 500) were obtained from a local hatchery and allocated randomly to five dietary treatments. This study conducted for 42d. Treatment groups included 1)CON(control), 2)T0.3(0.3% of thyme extract), 3)T0.6 (0.6% of thyme extract), 4) G0.3(0.3% of garlic extract) and 5)G0.6(0.6% of garlic extract). Thyme extract included 90μg/ml Carvacrol and 400mg/ml thymol while garlic extract included 100mg/ml elastin. There were no significant effects among the treatments on weight gain, feed intake and feed conversion ratio over the entire trial. Also, no significant differences were observed between CON group and other treatments in plasma parameters(cholesterol, triglyceride and HDL) and hematocrit. Sex of chickens had no effect on blood parameters. Supplementation of herb extracts did not affect carcass characteristics including carcass yield, breast, thigh and abdominal fat. There were no significant differences observed in carcass characteristics between males and females fed with different levels of herb extracts. In conclusion, supplementation of garlic and thyme extracts as feed additives at two levels of 3 and 6% in the present study did not improve performance and carcass traits of broiler chicks.
Anvar Zakirov,Chi Kyu Choi,An Soo Jung,Hyun Seung Kim,Rangaswamy Navamathavan,Yong Jun Jang 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.50 No.6
SiOC(-H) films were deposited on \emph{p}-Si (100) substrates by using plasma enhanced chemical vapor deposition with methyltrimethoxysilane (MTMS; C$_{4}$H$_{12}$O$_{3}$Si) and oxygen gas as precursors at different rf powers. In the SiOC(-H) film, the CH$_{3}$ group as an end group was introduced into the -O-Si-O- network, thereby reducing the density to decrease the dielectric constant. The flat-band voltage at the Al/SiOC(-H)/\emph{p}-Si(100) structure observed in the negative side is attributed to excess positive charge carriers in the form of -CH$_{3}$/Si-CH$_{3}$ and Si-H radicals in the film. The SiOC(-H) films deposited at different rf powers revealed the dominant mechanisms of space-charge-limited current followed by Poole-Frenkel emission. These results suggest that the electrical properties of the SiOC(-H) strongly depend on the excessive (Si-CH$_{3}$)$^{+}$ and (Si-O)$^{-}$ bonds present in the film.
FAP Inhibitors as Novel Small Molecules for Cancer Imaging using Radionuclide
Anvar Mirzaei,Jung-Joon Min,김동연 대한방사성의약품학회 2023 Journal of radiopharmaceuticals and molecular prob Vol.9 No.1
Tumors are encircled by various non-cancerous cell types in the extracellular matrix, including fibroblasts, endothelial cells, immune cells, and cytokines. Fibroblasts are the most critical cells in the tumor stroma and play an important role in tumor development, which has been highlighted in some epithelial cancers. Many studies have shown a tight connection between cancerous cells and fibroblasts in the last decade. Regulatory factors secreted into the tumor environment by special fibroblast cells, cancer-associated fibroblasts (CAFs), play an important role in tumor and vessel development, metastasis, and therapy resistance. This review addresses the development of FAP inhibitors, emphasizing the first, second, and latest generations. First-generation inhibitors exhibit low selectivity and chemical stability, encouraging researchers to develop new scaffolds based on preclinical and clinical data. Second-generation enzymes such as UAMC-1110 demonstrated enhanced FAP binding and better selectivity. Targeted treatment and diagnostic imaging have become possible by further developing radionuclide-labeled fibroblast activation protein inhibitors (FAPIs). Although all three FAPIs (01, 02, and 04) showed excellent preclinical and clinical findings. The final optimization of these FAPI scaffolds resulted in FAPI-46 with the highest tumor-to-background ratio and better binding affinity.
Performance Investigation of Space-Time Block Coded Multicarrier DS-CDMA in Time-Varying Channels
Anvar Narzullaev,류관웅,박용완 한국전자통신연구원 2006 ETRI Journal Vol.28 No.5
In this letter, we evaluate the system performance of a space-time block coded (STBC) multicarrier (MC) DS-CDMA system over a time selective fading channel, with imperfect channel knowledge. The average bit error rate impairment due to imperfect channel information is investigated by taking into account the effect of the STBC position. We consider two schemes: STBC after spreading and STBC before spreading in the MC DS-CDMA system. In the scheme with STBC after spreading, STBC is performed at the chip level; in the scheme with STBC before spreading, STBC is performed at the symbol level. We found that these two schemes have various channel estimation errors, and that the system with STBC before spreading is more sensitive to channel estimation than the system with STBC after spreading. Furthermore, derived results prove that a high spreading factor (SF) in the MC DS-CDMA system with STBC before spreading leads to high channel estimation error, whereas for a system with STBC after spreading this statement is not true.