Experimental and numerical study of transient flow in a centrifugal pump during startup

Zhifeng Li,Peng Wu,Dazhuan Wu,Leqin Wang 대한기계학회 2011 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.25 No.3

Transient characteristics and flows in a centrifugal pump during its starting period were experimentally and numerically investigated. The two-dimensional particle image velocimetry technique was used to capture transient flow evolutions in the pump’s diffuser. A new dynamic slip region method that combines the dynamic mesh method with the non-conformal grid boundaries is proposed to resolve the transient flows caused by the started impeller. Numerical self-coupling was realized by establishing a circulation pipe system along with the pump model equivalent to the experimental pump system. Numerical and experimental results agree well in both explicit characteristics and internal transient flow structures, confirming the validity of the proposed method. Analysis of the instantaneous flow in the impellers indicates that for the early stage of the startup, the transient vortex evolution between blades is the main reason for the transient head coefficient being lower than the steady state value. The reversed flow at the blade inlet is a less important reason for this effect. In later stages, the weakening of the intensity of the spatial vortex visible on S_2m and the main flow stream are the main reasons for the explicit performance slowly rebounding to the steady value.

A Discriminative Model for Age Invariant Face Recognition

Zhifeng Li,Unsang Park,Jain, A. K. IEEE 2011 IEEE transactions on information forensics and sec Vol.6 No.3

<P>Aging variation poses a serious problem to automatic face recognition systems. Most of the face recognition studies that have addressed the aging problem are focused on age estimation or aging simulation. Designing an appropriate feature representation and an effective matching framework for age invariant face recognition remains an open problem. In this paper, we propose a discriminative model to address face matching in the presence of age variation. In this framework, we first represent each face by designing a densely sampled local feature description scheme, in which scale invariant feature transform (SIFT) and multi-scale local binary patterns (MLBP) serve as the local descriptors. By densely sampling the two kinds of local descriptors from the entire facial image, sufficient discriminatory information, including the distribution of the edge direction in the face image (that is expected to be age invariant) can be extracted for further analysis. Since both SIFT-based local features and MLBP-based local features span a high-dimensional feature space, to avoid the overfitting problem, we develop an algorithm, called multi-feature discriminant analysis (MFDA) to process these two local feature spaces in a unified framework. The MFDA is an extension and improvement of the LDA using multiple features combined with two different random sampling methods in feature and sample space. By random sampling the training set as well as the feature space, multiple LDA-based classifiers are constructed and then combined to generate a robust decision via a fusion rule. Experimental results show that our approach outperforms a state-of-the-art commercial face recognition engine on two public domain face aging data sets: MORPH and FG-NET. We also compare the performance of the proposed discriminative model with a generative aging model. A fusion of discriminative and generative models further improves the face matching accuracy in the presence of aging.</P>

Gene Expression Patterns of Cutaneous Squamous Cell Carcinoma and Actinic Keratosis: Biomarkers Screening for Skin Disease Diagnosis

( Xiaojing Li ),( Zhifeng Li ),( Zhao Han ),( Ling Zhang ),( Zhao Liu ),( Baoguo Liu ) 대한피부과학회 2018 Annals of Dermatology Vol.30 No.5

Background: Actinic keratosis (AK) was an intraepidermal tumor which caused by ultraviolet irradiation-induced skin damage. Objective: The aim was to screen biomarkers for development of skin disease by comparing the gene expression profiles between cutaneous squamous cell carcinoma (CSCC) and AK. Methods: GSE45216 with 30 cutaneous squamous cell carcinoma patients and 10 actinic keratosis patients were downloaded and significance analysis of microarrays was processed to screen differently expressed genes (DEGs). Fisher’s exact test was processed for DEGs enrichment. Pathway relationship network systematically reflected the signal conduction and synergism between enriched pathways based on Kyoto Encyclopedia of Genes and Genomes database. Gene co-expression network was constructed according to gene expression data. Quantitative real- time-PCR was used to verify screened biomarkers. Results: Total 410 DEGs were screened and enriched into various functions, such as signal transduction and negative regu-lation of apoptotic process. They also participated into cytokine- cytokine receptor interaction and focal adhesion. The pathway relationship network was constructed with 27 nodes. Hub nodes with higher degree of this network were mitogen-activated protein kinase signaling pathway and apoptosis. The gene co-expression network was constructed with 39 nodes. Thereinto, hub node was ELOVL fatty acid elongase. The expression levels of ELOVL4 and HPGD were significantly higher in CSCC samples than that in AK samples, while the expression levels of INHBA and LAMC2 in CSCC samples were significantly lower than that in AK samples. Conclusion: These screened genes, including ELOVL4, HPGD, INHBA and LAMC2, played important roles in transformation from AK to CSCC. (Ann Dermatol 30(5) 536∼543, 2018)

Cross-architecture Binary Function Similarity Detection based on Composite Feature Model

( Xiaonan Li ),( Guimin Zhang ),( Qingbao Li ),( Ping Zhang ),( Zhifeng Chen ),( Jinjin Liu ),( Shudan Yue ) 한국인터넷정보학회 2023 KSII Transactions on Internet and Information Syst Vol.17 No.8

Recent studies have shown that the neural network-based binary code similarity detection technology performs well in vulnerability mining, plagiarism detection, and malicious code analysis. However, existing cross-architecture methods still suffer from insufficient feature characterization and low discrimination accuracy. To address these issues, this paper proposes a cross-architecture binary function similarity detection method based on composite feature model (SDCFM). Firstly, the binary function is converted into vector representation according to the proposed composite feature model, which is composed of instruction statistical features, control flow graph structural features, and application program interface calling behavioral features. Then, the composite features are embedded by the proposed hierarchical embedding network based on a graph neural network. In which, the block-level features and the function-level features are processed separately and finally fused into the embedding. In addition, to make the trained model more accurate and stable, our method utilizes the embeddings of predecessor nodes to modify the node embedding in the iterative updating process of the graph neural network. To assess the effectiveness of composite feature model, we contrast SDCFM with the state of art method on benchmark datasets. The experimental results show that SDCFM has good performance both on the area under the curve in the binary function similarity detection task and the vulnerable candidate function ranking in vulnerability search task.

Research on the Logical Evolution of Internationalization Strategy of Chinese Construction Enterprises Based on the Concept of Project Sharing

Shen Zhifeng,Li Meng,Li Yutao 인하대학교 국제관계연구소 2022 Pacific Focus Vol.37 No.2

Under the initiative of “One Belt, One Road,” Chinese construction enterprises are facing problems such as project failures, budget overruns, and inadequate strategic positioning in the process of promoting their internationalization strategies in view of the increasingly tense situation of “Thucydides's Trap,” “America First,” and “Kindleberger Trap.” Chinese construction enterprises should adjust their international strategic logic to reconstruct the relationship between the internationalization strategy of the construction enterprises and the project sharing concept. This article analyzes the relationship between project sharing and the success of internationalization strategy of construction enterprises by elaborating on the connotation and concept of internationalization strategy and project sharing of construction enterprises. Based on the analysis of the project sharing concept, this article puts forward the evolutionary logic of internationalization strategy of Chinese construction enterprises in four stages, and analyzes the strategic logic of “winning” internationalization of construction enterprises based on the concept of project sharing. The research results provide new ideas and methods for Chinese construction enterprises to carry out international project cooperation and formulate international strategy, which has important theoretical and practical value.

A Review on Energy Consumption and Efficiency of Selective Laser Melting Considering Support: Advances and Prospects

Qingyang Wang,Mengdi Gao,Qiang Li,Conghu Liu,Lei Li,Xinyu Li,Zhifeng Liu 한국정밀공학회 2024 International Journal of Precision Engineering and Vol.11 No.1

Selective laser melting (SLM) exhibits excellent manufacturing accuracy and forming ability. However, the laser beam layering process is characterized by high specific energy consumption, long manufacturing cycle, and low energy efficiency. The use of supports increases the SLM building quality and eliminates defects caused by thermal and residual stresses; however, an improper support structural design increases the process energy consumption for manufactured parts. To control energy consumption and building quality during SLM, this study first discusses the main challenges related to energy saving and improving the building quality by performing an energy consumption analysis, process energy consumption optimization, and supporting structure optimization. The obtained results reveal that it is difficult to achieve high building quality only by controlling the process parameters and energy consumption by the SLM equipment. Next, the effect of supporting structures on the process energy consumption is examined to enable the construction of an SLM energy consumption model that considers the presence of supports. Finally, the effect of supports on the building quality is elucidated by studying the influence of supporting structures on thermal and residual stresses. By identifying the most energy-efficient support, the process energy efficiency and building quality may be simultaneously optimized. The proposed method represents a new approach to reducing energy consumption and improving the building quality during SLM. This study establishes a theoretical foundation for the subsequent industrial applications, providing a thorough literature review and describing the existing challenges in the SLM manufacturing field.

Investigation on Chain Transfer Reaction of Benzene Sulfonyl Chloride in Styrene Radical Polymerization

Li, Cuiping,Fu, Zhifeng,Shi, Yan The Polymer Society of Korea 2009 Macromolecular Research Vol.17 No.8

The free radical polymerization of styrene was initiated with azobis(isobutyronitrile) in the presence of benzene sulfonyl chloride. Analysis of the terminal structures of the obtained polystyrene with $^1H$ NMR spectroscopy revealed the presence of a phenyl sulfonyl group at the ${\alpha}$-end and a chlorine atom at the ${\omega}$-end of each polystyrene chain. The terminal chlorine atom in the polystyrene chains was further confirmed through atom transfer radical polymerization (ATRP) of styrene and methyl acrylate using the obtained polystyrenes as macroinitiators and CuCl/2,2'-bipyridine as the catalyst system. GPC traces of the products obtained in ATRP at different reaction times were clearly shifted to higher molecular weight direction, indicating that nearly all the macroinitiator chains initiated ATRP of the second monomers. In addition, the number-average molecular weights of the polystyrenes increased directly proportional to the monomer conversions, and agreed well with the theoretical ones.

A Novel Electrochemical Method for Sensitive Detection of Melamine in Infant Formula and Milk using Ascorbic Acid as Recognition Element

Li, Junhua,Kuang, Daizhi,Feng, Yonglan,Zhang, Fuxing,Xu, Zhifeng,Liu, Mengqin Korean Chemical Society 2012 Bulletin of the Korean Chemical Society Vol.33 No.8

A novel and convenient electrochemical method has been developed for sensitive determination of melamine (MEL) using ascorbic acid (AA) as the recognition element. The working electrode employed in this method was modified with the nanocomposite of hydroxyapatite/carbon nanotubes to enhance the current signal of recognition element. The interaction between MEL and AA was investigated by fourier transform infrared spectroscopy and cyclic voltammetry, and the experimental results indicated that hydrogen bonding was formed between MEL and AA. Because of the existing hydrogen bonding and electrostatic interaction, the anodic peak current of AA was decreased obviously while the non-electroactive MEL added in. It illustrated that the MEL acted as an inhibitor to the oxidation of AA and the decreasing signals can be used to detect MEL. Under the optimal conditions, the decrease in anodic peak current of AA was proportional to the MEL concentrations ranging from 10 to 350 nM, with a detection limit of 1.5 nM. Finally this newly-proposed method was successfully employed to detect MEL in infant formula and milk, and good recovery was achieved.

Design Method of Active Disassembly Structure Triggered by Temperature-Pressure Coupling

Zhifeng Liu,Yifei Zhan,Huanbo Cheng,Xinyu Li,Shaobo Pan 한국정밀공학회 2013 International Journal of Precision Engineering and Vol. No.

Active disassembly products often use active disassembly structures triggered by single temperature or pressure field as reversible joints. These structures can be triggered automatically in extreme or accidental circumstances, thus causing the low reliability of products. For improving the reliability of active disassembly products, working mechanisms of active disassembly structure triggered by temperature-pressure coupling is presented in this article. Through analyzing some typical active disassembly structures, this article presents the design criteria and methods of active disassembly structure triggered by temperature-pressure coupling. The feasibility of these design methods is proved by a case analysis. The results of research shows that the reliability of active disassembly structures triggered by temperature-pressure coupling is improved greatly, which can lay the foundation for the industrial applications of active disassembly methods.

Development of covalent inhibitors that can overcome resistance to first-generation FGFR kinase inhibitors

Tan, Li,Wang, Jun,Tanizaki, Junko,Huang, Zhifeng,Aref, Amir R.,Rusan, Maria,Zhu, Su-Jie,Zhang, Yiyun,Ercan, Dalia,Liao, Rachel G.,Capelletti, Marzia,Zhou, Wenjun,Hur, Wooyoung,Kim, NamDoo,Sim, Taebo,G National Academy of Sciences 2014 PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF Vol.111 No.45

<P><B>Significance</B></P><P>Inhibitors of the FGF receptors (FGFRs) are currently under clinical investigation for the treatment of various cancers. All currently approved kinase inhibitors eventually are rendered useless by the emergence of drug-resistant tumors. We used structure-based drug design to develop the first, to our knowledge, selective, next-generation covalent FGFR inhibitors that can overcome the most common form of kinase inhibitor resistance, the mutation of the so-called “gatekeeper” residue located in the ATP-binding pocket. We also describe a novel kinase inhibitor design strategy that uses a single electrophile to target covalently cysteines that are located in different positions within the ATP-binding pocket. These results have important implications for the design of covalent FGFR inhibitors that can overcome clinical resistance.</P><P>The human FGF receptors (FGFRs) play critical roles in various human cancers, and several FGFR inhibitors are currently under clinical investigation. Resistance usually results from selection for mutant kinases that are impervious to the action of the drug or from up-regulation of compensatory signaling pathways. Preclinical studies have demonstrated that resistance to FGFR inhibitors can be acquired through mutations in the FGFR gatekeeper residue, as clinically observed for FGFR4 in embryonal rhabdomyosarcoma and neuroendocrine breast carcinomas. Here we report on the use of a structure-based drug design to develop two selective, next-generation covalent FGFR inhibitors, the FGFR irreversible inhibitors 2 (FIIN-2) and 3 (FIIN-3). To our knowledge, FIIN-2 and FIIN-3 are the first inhibitors that can potently inhibit the proliferation of cells dependent upon the gatekeeper mutants of FGFR1 or FGFR2, which confer resistance to first-generation clinical FGFR inhibitors such as NVP-BGJ398 and AZD4547. Because of the conformational flexibility of the reactive acrylamide substituent, FIIN-3 has the unprecedented ability to inhibit both the EGF receptor (EGFR) and FGFR covalently by targeting two distinct cysteine residues. We report the cocrystal structure of FGFR4 with FIIN-2, which unexpectedly exhibits a “DFG-out” covalent binding mode. The structural basis for dual FGFR and EGFR targeting by FIIN3 also is illustrated by crystal structures of FIIN-3 bound with FGFR4 V550L and EGFR L858R. These results have important implications for the design of covalent FGFR inhibitors that can overcome clinical resistance and provide the first example, to our knowledge, of a kinase inhibitor that covalently targets cysteines located in different positions within the ATP-binding pocket.</P>