Comparative study of tip leakage vortex trajectory and cavitation in an axial flow pump with various tip clearances

Xi Shen,Desheng Zhang,Bin Xu,Haoran Wu,Peng Wang,Weidong Shi 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.3

In order to analyze the effect of blade tip-gap size on the tip leakage vortex (TLV) dynamics and TLV-induced cavitation, a scaled axial flow pump model was created and numerically studied by the combination of an improved SST k-ω turbulence model and a homogeneous cavitation model. The trajectories of TLV core was obtained by using the swirling strength method at different tip-gap sizes vary significantly. The scale of TLV increases as the tip-gap size increases, and the starting point of TLV is sliding further downstream along the blade chord. The angle between the blade suction surface and the TLV also presented an increasing trend with the tip-gap size. The statistics of the velocity normal to the tip chord, as well as the turbulent kinetic energy (KTE) distributions were employed to illustrate a more disordered flow field, which was generated in the tip clearance in a larger amount of leaking flow due to the increased tip-gap size. The in-plain static pressure and vapor volume fraction distributions at different blade chord sections, coupled with three-dimensional cavitation patterns among three tip gaps, are further analyzed to verify the wandering motion of TLV, which shows good agreement with the visualization experiment. Considering the adverse effect of the TLV cavitation, a small tip gap is recommended for improving the axial flow pump performance.

Application of Horizontal Wells to Reduce Water Production during Gel Treatment

Shen, Guang Xi,Lee, Ji Ho,Lee, Kun Sang Trans Tech Publications, Ltd. 2013 Advanced materials research Vol.807 No.-

<P>It is well known that gel treatment has outstanding potential to delay water breakthrough and reduce water production. However, it causes the decrease of oil production by permeability reduction, even though it is not as much as reduction of water production. For this reason, to improve oil production with substantial reduction of water production, performances of gel treatments through the combination of horizontal and/or vertical wells were assessed and compared. An extensive numerical simulation was executed for four different well configurations under gel treatment associated with waterflood to accomplish the purpose of this study. Performances were compared according to cumulative oil recovery and water-oil ratio at the production well for different systems. Though all of well configurations considered in this study effectively decreased the water production compared with waterflood, applications of horizontal wells led to much higher oil recovery than vertical well because of improved sweep efficiency. Based on these results, the potential of horizontal wells was examined through different scenarios in combinations of injection and production wells. Furthermore, various well lengths of injectors or producers were assessed for horizontal wells. Because cross-flow between layers dominates performance of gel treatment, effects of vertical permeability were also investigated in application of gel treatment with horizontal well. Longer wells and higher cross-flow results in better performance. This study represents that effectiveness of horizontal wells for gel treatment even for reservoirs having dominant cross-flow.</P>

Prognostic Significance of Tumor Mutation Burden among Patients with Non-small Cell Lung Cancer Who Received Platinum-based Adjuvant Chemotherapy: An Exploratory Study

Wei-Xi Shen,Guang-Hua Li,Yu-Jia Li,Peng-Fei Zhang,Jia-Xing Yu,Di Shang,Qiu-Shi Wang 대한암예방학회 2023 Journal of cancer prevention Vol.28 No.4

This study aimed to investigate the prognostic significance of tumor mutation burden (TMB) among patients with non-small cell lung cancer (NSCLC) who received platinum-based adjuvant chemotherapy. Tumor tissue specimens after surgical resection were collected for DNA extraction. Somatic mutation detection and TMB analysis were conducted using next-generation sequencing (NGS). Recurrence status of the patients was assessed in the hospital during the adjuvant chemotherapy period, and long-term survival data of patients were obtained by telephone follow-up. Univariate analysis between TMB status and prognosis was carried out by survival analysis. A retrospective review of 78 patients with non-squamous NSCLC who received platinum-based adjuvant chemotherapy showed a median disease-free survival of 3.6 years and median overall survival (OS) of 5.3 years. NGS analysis exhibited that the most common mutated somatic genes among the 78 patients were tumor suppressor protein p53 (TP53), epidermal growth factor receptor, low-density lipoprotein receptor related protein 1B, DNA methyltransferase 3 alpha and FAT atypical cadherin 3, and their prevalence was 56.4%, 48.7%, 37.2%, 30.7%, and 25.6%, respectively. TMB status was divided into TMB-L (≤ 4.5/Mb) and TMB-H (> 4.5/Mb) based on the median TMB threshold. Relevance of TMB to prognosis suggested that the median OS of patients with TMB-L was significantly longer than that of patients with TMB-H (NR vs. 4.6, P = 0.014). Higher TMB status conferred a worse implication on OS among patients with non-squamous NSCLC who received platinum-based adjuvant chemotherapy.

PGA: An Efficient Adaptive Traffic Signal Timing Optimization Scheme Using Actor-Critic Reinforcement Learning Algorithm

( Si Shen ),( Guojiang Shen ),( Yang Shen ),( Duanyang Liu ),( Xi Yang ),( Xiangjie Kong ) 한국인터넷정보학회 2020 KSII Transactions on Internet and Information Syst Vol.14 No.11

Advanced traffic signal timing method plays very important role in reducing road congestion and air pollution. Reinforcement learning is considered as superior approach to build traffic light timing scheme by many recent studies. It fulfills real adaptive control by the means of taking real-time traffic information as state, and adjusting traffic light scheme as action. However, existing works behave inefficient in complex intersections and they are lack of feasibility because most of them adopt traffic light scheme whose phase sequence is flexible. To address these issues, a novel adaptive traffic signal timing scheme is proposed. It's based on actor-critic reinforcement learning algorithm, and advanced techniques proximal policy optimization and generalized advantage estimation are integrated. In particular, a new kind of reward function and a simplified form of state representation are carefully defined, and they facilitate to improve the learning efficiency and reduce the computational complexity, respectively. Meanwhile, a fixed phase sequence signal scheme is derived, and constraint on the variations of successive phase durations is introduced, which enhances its feasibility and robustness in field applications. The proposed scheme is verified through field-data-based experiments in both medium and high traffic density scenarios. Simulation results exhibit remarkable improvement in traffic performance as well as the learning efficiency comparing with the existing reinforcement learning-based methods such as 3DQN and DDQN.

Present Situation and Prospects of Sericulture in China

Shen, Xing-Jia,Ye, Xia-Yu,Guo, Xi-Jie Korean Society of Sericultural Science 2006 International Journal of Industrial Entomology Vol.13 No.2

Since 1970, China has become the biggest cocoon producer in the world, and made the highest historical record of cocoon output for 759,800 tons in 1995. However, in 1996 cocoon production reduced sharply to 470,900 tons. After a ten-year adjustment and reform, sericultural areas have shifted from developed regions to developing regions and from the east to the west. From 2000, the cocoon output has started to increase restoringly. By 2004 it recovered to 547,091 tons. With the development of market economy, sericulture management has been changed, including mulberry fields concentrated to the specializated households and cooperatives, cocoons produced in larger scale instead of individuals, Silkworm egg producing enterprises gradually changed into non-governmental joint-stock ones. The mechanism of market cocoon price has been gradually established. The management model of combination of trade, industry and agriculture is pushing and improving. It is the fruit of modern science and technology, especially sericultural basic research, that provides China's sericulture with the opportunity and vital force. China's sericulture, therefore, will continue to develop steadily in future.

PCR Identification and Phylogenetic Analysis of Trichomonas gallinae from Domestic Pigeons in Guangzhou, China

Shen-Ben Qiu,Meng-Na Lv,Xi He,Ya-Biao Weng,Shang-Shu Zou,Xin-Qiu Wang,Rui-Qing Lin 대한기생충학열대의학회 2017 The Korean Journal of Parasitology Vol.55 No.3

Is transurethral needle ablation of prostate out of fashion? Outcomes of single session office-based transurethral needle ablation of prostate in patients with symptomatic benign prostatic hyperplasia

Yu Xi Terence Law,Wei Jing Kelven Chen,Liang Shen,Wei Jin Chua 대한비뇨의학회 2019 Investigative and Clinical Urology Vol.60 No.5

Purpose: Transurethral needle ablation (TUNA) is a minimally invasive procedure for the treatment of symptomatic benign prostatic hyperplasia (BPH). Compared to transurethral resection of the prostate (TURP), office-based TUNA is an attractive alternative as it is minimally invasive and avoids general anaesthesia. The aim of this study is to evaluate the efficacy of single session office-based TUNA. Materials and Methods: Data of 121 patients who had undergone TUNA was retrieved from June 2008 to March 2017. Patients were followed-up with visits at 1, 3, 6, and 12-months with the International Prostate Symptom Score (IPSS), quality of life (QoL) scoring and uroflowmetry. Results: Patients were 39 to 85 years old. The prostate volumes were 20.00 to 96.90 mL with a median of 26.95 mL. The median IPSS score pre-TUNA was 19, median QOL score pre-TUNA was 4 and median maximum urinary flow (Qmax) pre-TUNA was 10.3 mL/s. There is 65% improvement of IPSS post-TUNA (p<0.001). There is 75% improvement of QOL post-TUNA QOL (p<0.001). There is 35% improvement of Qmax post-TUNA Qmax (p<0.001). The mean relapse-free survival for TUNA is 6.123 years. The 1st, 3rd, and 5th year relapse-free survival rate were 91.7%, 76.6% and 63.7% respectively. Conclusions: Our study is the first to investigate the use of a single-setting office-based TUNA requiring minimal sedation in the Asian community. Complication rates were low in our series, with no associated mortality. When applied to selected patients, TUNA is an effective and reasonably safe alternative for the treatment of symptomatic BPH.

Beta-asarone Induces LoVo Colon Cancer Cell Apoptosis by Up-regulation of Caspases through a Mitochondrial Pathway in vitro and in vivo

Zou, Xi,Liu, Shen-Lin,Zhou, Jin-Yong,Wu, Jian,Ling, Bo-Fan,Wang, Rui-Ping Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.10

Beta-asarone is one of the main bioactive constituents in traditional Chinese medicine Acorus calamu. Previous studies have shown that it has antifungal and anthelmintic activities. However, little is known about its anticancer effects. This study aimed to determine inhibitory effects on LoVo colon cancer cell proliferation and to clarify the underlying mechanisms in vitro and in vivo. Dose-response and time-course anti-proliferation effects were examined by MTT assay. Our results demonstrated that LoVo cell viability showed dose- and time-dependence on ${\beta}$-asarone. We further assessed anti-proliferation effects as ${\beta}$-asarone-induced apoptosis by annexin V-fluorescein isothiocyanate/propidium iodide assay usinga flow cytometer and observed characteristic nuclear fragmentation and chromatin condensation of apoptosis by microscopy. Moreover, we found the apoptosis to be induced through the mitochondrial/caspase pathway by decreasing mitochondrial membrane potential (MMP) and reducing the Bcl-2-to-Bax ratio, in addition to activating the caspase-9 and caspase-3 cascades. Additionally, the apoptosis could be inhibited by a pan-caspase inhibitor, carbobenzoxy-valyl-alanyl-aspartyl-[O-methyl]-fluoromethylketone (Z-VAD-FMK). When nude mice bearing LoVo tumor xenografts were treated with ${\beta}$-asarone, tumor volumes were reduced and terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL) assays of excised tissue also demonstrated apoptotic changes. Taken together, these findings for the first time provide evidence that ${\beta}$-asarone can suppress the growth of colon cancer and the induced apoptosis is possibly mediated through mitochondria/caspase pathways.

Experimental study on propagation behavior of three-dimensional cracks influenced by intermediate principal stress

Sun, Xi Z.,Shen, B.,Zhang, Bao L. Techno-Press 2018 Geomechanics & engineering Vol.14 No.2

Many laboratory experiments on crack propagation under uniaxial loading and biaxial loading have been conducted in the past using transparent materials such as resin, polymethyl methacrylate (PMMA), etc. However, propagation behaviors of three-dimensional (3D) cracks in rock or rock-like materials under tri-axial loading are often considerably different. In this study, a series of true tri-axial loading tests on the rock-like material with two semi-ellipse pre-existing cracks were performed in laboratory to investigate the acoustic emission (AE) characteristics and propagation characteristics of 3D crack groups influenced by intermediate principal stress. Compared with previous experiments under uniaxial loading and biaxial loading, the tests under true tri-axial loading showed that shear cracks, anti-wing cracks and secondary cracks were the main failure mechanisms, and the initiation and propagation of tensile cracks were limited. Shear cracks propagated in the direction parallel to pre-existing crack plane. With the increase of intermediate principal stress, the critical stress of crack initiation increased gradually, and secondary shear cracks may no longer coalesce in the rock bridge. Crack aperture decreased with the increase of intermediate principal stress, and the failure is dominated by shear fracturing. There are two stages of fracture development: stable propagation stage and unstable failure stage. The AE events occurred in a zone parallel to pre-existing crack plane, and the AE zone increased gradually with the increase of intermediate principal stress, eventually forming obvious shear rupture planes. This shows that shear cracks initiated and propagated in the pre-existing crack direction, forming a shear rupture plane inside the specimens. The paths of fracturing inside the specimens were observed using the Computerized Tomography (CT) scanning and reconstruction.

Discovery of New S-RNase Genes and Identification of S-genotype in Japanese Plum (Prunus salicina Lindl.)

Shao Xi Huang,Shao Ling Zhang,Hua Qing Wu,Hong Feng Song,Zhi Jun Shen,Yang Rui Li 한국원예학회 2006 한국원예학회 기타간행물 Vol.- No.-