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Zihua Liu,Di Wang,Ren Liang,Dechang Cai,Yong Ouyang,Zhikang Lin 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.9
In this paper, a single-equation drift-flux type model for gas-lead-bismuth eutectic (LBE) two-phase flow analysis in the LBE fast reactor steam generator tube rupture (SGTR) accident is established. As the area-averaged superficial gas velocity increases, the calculated exponent P in the Bankoff model increases, and the distribution parameter C 0 decreases. The reliability of the model is confirmed by comparing the predicted results with a total of 76 sets of open experimental data from a bubble-column case and a gas lift pump case. The relative deviation between the predicted and experimental values of the void fraction is within 20 %. The model proposed in this paper helps to realize the early warning and analysis of SGTR accidents in LBE fast reactors, and can provide theoretical and technical guidance for the safety design and evaluation of LBE fast reactors.
Zihua Liu,Hao Zhou,Hao Fang,Mingxi Zhou 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.6
Perforated plates have been widely used to attenuate harmful noise. An impedance tube was used to evaluate the sound absorption capacities of four cases of dual perforated plates with multiple apertures traversed by bias flow. The radius of small holes on the plates was 1.0 mm, and the radii of large holes were 1.5 mm, 2.0 mm, 2.5 mm, and 3.0 mm, respectively. The effects of the frequency and amplitude of the incident sound wave, the cavity depths, and the bias flow velocity on the sound attenuation effect of these cases were experimentally studied. The maximum sound absorption coefficient of dual perforated plates with the large difference in hole size was 0.93. On the other hand, the dual plates with the small aperture difference is more adaptable to the change of the bias flow velocity, and the maximum sound absorption coefficient was close to 1.
Zihua Hu,Changjiang Qin,Xiaogao Chen,Aimin Tang,Tao Fang,Zhiping Yang,Sheng Luo,Meijiao Mao 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.8
To extend the tool life of conventional uncoated grinding cemented carbide inserts (CUG inserts) in turning GH4169 nickelbased superalloy, chemical–mechanical polishing (CMP) is applied to appropriately treat the rake face of the CUG insert to address the defects including grinding burn, crack, and thermal deformation. The material removal rate (MRR) and the rake face roughness Ra of YG10 chemical–mechanical polished cemented carbide inserts (CMP inserts) corresponding to the six types of abrasives particles are investigated by applying the single factor method, and the diamond powder is the most suitable to polish YG10 inserts. Thus, CMP parameters are optimized using Taguchi method coupled with both the grey relation analysis and fuzzy inference. Furthermore, the comparison experiments of the cutting performance of the CUG insert and the CMP insert in turning GH4169 are carried out, under the same cutting condition, compared with the CUG insert, the average tool life of the CMP insert is increased by 35.92%. This study demonstrates that the CMP technique is an effective potential method to improve the surface integrity, the cutting performance and the tool life of conventional uncoated grinding cemented carbide inserts & tools in the machining of difficult-to-cut materials.
BACH1/FANCJ Acts with TopBP1 and Participates Early in DNA Replication Checkpoint Control
Gong, Zihua,Kim, Ja-Eun,Leung, Charles Chung Yun,Glover, J.N. Mark,Chen, Junjie Elsevier 2010 Molecular cell Vol.37 No.3
<P><B>Summary</B></P><P>Human TopBP1 plays a critical role in the control of DNA replication checkpoint. In this study, we report a specific interaction between TopBP1 and BACH1/FANCJ, a DNA helicase involved in the repair of DNA crosslinks. The TopBP1/BACH1 interaction is mediated by the very C-terminal tandem BRCT domains of TopBP1 and S phase-specific phosphorylation of BACH1 at Thr 1133 site. Interestingly, we demonstrate that depletion of TopBP1 or BACH1 attenuates the loading of RPA on chromatin. Moreover, both TopBP1 and BACH1 are required for ATR-dependent phosphorylation events in response to replication stress. Taken together, our data suggest that BACH1 has an unexpected early role in replication checkpoint control. A specific interaction between TopBP1 and BACH1 is likely to be required for the extension of single-stranded DNA regions and RPA loading following replication stress, which is a prerequisite for the subsequent activation of replication checkpoint.</P> <P><B>Highlights</B></P><P>► Human TopBP1 interacts with BACH1 in a phosphorylation-dependent manner ► TopBP1 or BACH1 depletion attenuates RPA chromatin loading after replication stress ► Both TopBP1 and BACH1 are required for ATR-dependent replication checkpoint activation</P>
Gong, Zihua,Cho, Young-Wook,Kim, Ja-Eun,Ge, Kai,Chen, Junjie American Society for Biochemistry and Molecular Bi 2009 The Journal of biological chemistry Vol.284 No.11
<P>Genomic stability in eukaryotic cells is maintained by the coordination of multiple cellular events including cell cycle checkpoint, DNA repair, transcription, and apoptosis after DNA damage. Pax2 transactivation domain interaction protein (PTIP), a protein that contains six BRCT domains, has been implicated in DNA damage response. In this study we showed that recruitment of PTIP to damaged chromatin depends on DNA damage signaling proteins gammaH2AX.MDC1.RNF8, which in turn facilitates sustained localization of PA1 (PTIP-associated protein 1) to sites of DNA break. Similar to PTIP, depletion of PA1 increases cellular sensitivity to ionizing radiation. Furthermore, we demonstrated that the N-terminal PA1 binding domain and the C-terminal focus-localization domain of PTIP are critical for PTIP function in DNA damage repair. Interestingly, although PTIP and PA1 associate with MLL (mixed lineage leukemia) complexes and participate in transcriptional regulation, this function of PTIP.PA1 in DNA damage response is likely to be independent of the MLL complexes. Taken together, we propose that a subset of PTIP.PA1 complex is recruited to DNA damage sites via the RNF8-dependent pathway and is required for cell survival in response to DNA damage.</P>
( Hongtao Zhang ),( Zihua Yang ),( Yunfan Ye ) 한국인터넷정보학회 2016 KSII Transactions on Internet and Information Syst Vol.10 No.11
Femtocells are envisioned as a key solution to embrace the ever-increasing high data rate and thus are extensively deployed. However, the dense and random deployments of femtocell access points (FAPs) induce severe intercell inference that in turn may degrade the performance of spectral efficiency. Hence, unrestrained proliferation of FAPs may not acquire a net throughput gain. Besides, given that numerous FAPs deployed in ultra-dense networks (UDNs) lead to significant energy consumption, the amount of FAPs deployed is worthy of more considerations. Nevertheless, little existing works present an analytical result regarding the optimal FAP density for a given User Equipment (UE) density. This paper explores the realistic scenario of randomly distributed FAPs in UDN and derives the coverage probability via Stochastic Geometry. From the analytical results, coverage probability is strictly increasing as the FAP-to-UE ratio increases, yet the growing rate of coverage probability decreases as the ratio grows. Therefore, we can consider a specific FAP-to-UE ratio as the point where further increasing the ratio is not cost-effective with regards to the requirements of communication systems. To reach the optimal FAP density, we can deploy FAPs in line with peak traffic and randomly switch off FAPs to keep the optimal ratio during off-peak hours. Furthermore, considering the unbalanced nature of traffic demands in the temporal and spatial domain, dynamically and carefully choosing the locations of active FAPs would provide advantages over randomization. Besides, with a huge FAP density in UDN, we have more potential choices for the locations of active FAPs and this adds to the demand for a strategic sleeping policy.
Hao Zhou,Zihua Liu,Hao Fang,Chengfei Tao,Mingxi Zhou,Liubin Hu 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.11
Perforated plates have been widely used in combustors to attenuate harmful sounds. In this study, the acoustic absorption capability of plates with heterogeneously distributed holes under bias flow was evaluated in an impedance tube, and the sound attenuation effect of each plate located in the liquid fuel combustor inlet section was experimentally studied. The perforated plate with heterogeneously distributed large holes showed the best control effect under the designed experimental conditions. After control, the peak dynamic pressure in the chamber and plenum decreased by 90 % and 75 %, respectively, and the reduction in the heat release fluctuation was 60 %. When the primary air flow rate deviated from the optimal value, the plate with large holes still reduced the pressure amplitude in the chamber by approximately 70 %. It was also found that installing the perforated plate with a back cavity had the dual effect of gaining and damping combustion instability.