Global Power Transitions and Their Implications for the 21st Century

Yi Feng 인하대학교 국제관계연구소 2013 Pacific Focus Vol.28 No.2

This essay presents a theoretical approach toward war and peace, reviews basic conditions for world leadership, discusses four modes of global power transitions, illuminates the likely emergence of the future superpowers, and summarizes the differences and common interests between the United States,the incumbent world leader, and China, a potential contender for the global leadership in the 21st century. The theoretical background is powertransition theory, which predicts war when superpowers are close in power and peace when power preponderance exists. Power parity need be also considered in the context of common interests and preferences of superpowers. Conflict abates when the nations share fundamental rules of the game in world affairs. Four historical modes of transitions – co-dominion, deterrence,confrontation, and cooperation – were identified. Of the four historical transitions, each time, the challenger surpassed the hegemon in economic power, and deterrence and confrontation by the hegemon against the challenger did not prevent the challenger from assuming global leadership in the long term. Among the newly rising nations (BRICs), China is discussed as a potential contender for world leadership. The economic and financial interdependence between the United States and China is currently the driving force in their relations. It shapes their political arrangements, necessitating coordination and cooperation in policy issues. While economic collaboration and interdependence drive the relations between the two, they are not suffi-cient conditions for a peaceful transition, until their political and security relations are solidified and their preferences coalesce substantively.

Multiscale singular value manifold for rotating machinery fault diagnosis

Yi Feng,Baochun Lu,Dengfeng Zhang 대한기계학회 2017 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.31 No.1

Time-frequency distribution of vibration signal can be considered as an image that contains more information than signal in time domain. Manifold learning is a novel theory for image recognition that can be also applied to rotating machinery fault pattern recognition based on time-frequency distributions. However, the vibration signal of rotating machinery in fault condition contains cyclical transient impulses with different phrases which are detrimental to image recognition for time-frequency distribution. To eliminate the effects of phase differences and extract the inherent features of time-frequency distributions, a multiscale singular value manifold method is proposed. The obtained low-dimensional multiscale singular value manifold features can reveal the differences of different fault patterns and they are applicable to classification and diagnosis. Experimental verification proves that the performance of the proposed method is superior in rotating machinery fault diagnosis.

“Entanglement of Echoes in Near / Miss” : Bernstein, Charles. Near / Miss Chicago: U of Chicago P, 2018.

( Yi Feng ) 한국영어영문학회 2018 영어 영문학 Vol.64 No.2

Recent advances in transition metal layered double hydroxide based materials as efficient electrocatalysts

Yi Feng,Lei Chen,Zhong-Yong Yuan 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.120 No.-

The development of efficient electrocatalysts occupies a vital position in achieving efficient energy conversionand storage. Transition-metal-based layered double hydroxides (TM LDHs) featuring unique layeredstructure have received extensive attention in the field of designing highly cost-effectiveelectrocatalysts. Nevertheless, the practical application of TM LDH-based electrocatalysts still faces a seriesof challenges including insufficient active sites, inferior intrinsic conductivity and suboptimal robustness. Throughout this review, the most recent researches dedicated to TM LDH-based electrocatalysts arereviewed in terms of structural features, synthetic strategies, modification approaches and electrocatalyticapplications. This review focuses on the effective modification approaches and important electrochemicalapplications of TM LDHs. This review supplies the conducive tools to select the appropriatetechnics for adequately boosting the electrocatalytic performance of TM LDH-based electrocatalystsand concludes with a salient summary outlining orientations for further research.

Ameliorative effects of Lycium chinensis on male sexual dysfunction and testicular oxidative damage in streptozotocin-induced diabetic rats

Yifeng Zhou,Opeyemi Joshua Olatunji,Hongxia Chen 한국식품과학회 2019 Food Science and Biotechnology Vol.28 No.4

The root bark of Lycium chinense (LC) has beenreported to have potent antioxidant and antidiabetic properties. In the present study, we investigated the attenuativeeffect of LC against diabetes induced sexual dysfunctionand testicular damages in animal models. Diabetic animalswere treated with LC (100 and 400 mg/kg) once daily for6 weeks. At the end of the treatment, mating behavior testswere performed and the animals were sacrificed for thedetermination of hormonal profile, oxidative stress indicesand sperm analysis. LC administration significantlydecreased blood glucose level, enhancement of theantioxidant enzyme activities, restored altered spermcharacteristics and markedly improved levels of luteinizinghormone, follicle-stimulating hormone and testosterone ascompared to the untreated diabetic animals. Furthermore,LC also improved sperm count, viability, motility,increased the reproductive organs weight. The resultsobtained indicated that L. chinense has beneficial effects indiabetes sexual dysfunction.

A Parameter Selection Method for Multi-Element Resonant Converters with a Resonant Zero Point

Yifeng Wang,Liang Yang,Guodong Li,Shijie Tu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.2

This paper proposes a parameter design method for multi-element resonant converters (MERCs) with a unique resonant zero point (RZP). This method is mainly composed of four steps. These steps include program filtration, loss comparison, 3D figure fine-tuning and priority compromise. It features easy implementation, effectiveness and universal applicability for almost all of the existing RZP-MERCs. Meanwhile, other design methods are always exclusive for a specific topology. In addition, a novel dual-CTL converter is also proposed here. It belongs to the RZP-MERC family and is designed in detail to explain the process of parameter selection. The performance of the proposed method is verified experimentally on a 500W prototype. The obtained results indicate that with the selected parameters, an extensive dc voltage gain is obtained. It also possesses over-current protection and minimal switching loss. The designed converter achieves high efficiencies among wide load ranges, and the peak efficiency reaches 96.9%.

Researching Indistinguishability of the Polymorphism Time Stamp Watermarking

Yifeng Yin,Heyu Wen,Kunpeng Fan 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.7

With the rapid development of computer network, digital watermarking, which is an effective digital products copyright protection technology, was widely applied in the security forensic. Those were analyzed that are the defects of existing time stamp scheme of digital watermarking and the characteristics of the pseudo-random sequence. The new scheme based on time stamp and pseudo-random sequence was proposed. Indistinguishability and scalability of watermark were analyzed from the experimental results. And other two aspects were obviously improved in the new scheme, which were in improving protocol’s security and reducing the quantity of data embedded in digital works.

Study on load distribution ratio of composite pre-tightened tooth joint by shear nonlinearity

Yifeng Gao,Fei Li,Qilin Zhao,Jiangang Gao,Lin Shi,Zhiqin Zhao 국제구조공학회 2021 Steel and Composite Structures, An International J Vol.40 No.5

Load distribution has a great influence on the mechanical properties of composite pre-tightened multi-tooth connection. To obtain the load distribution mechanism of composite pre-tightened multi-tooth joints, the multi-tooth joints were studied by experimental and theoretical methods. First, an experimental study was conducted on three-tooth specimens with different tooth depths and tooth lengths, and the failure mode, bearing capacity and load distribution mechanism of the specimens were obtained. Then, based on the nonlinear constitutive of interlaminar shear, an analytical model for load distribution of composite pre-tightened multi-tooth joint was proposed to research the multi-tooth load distribution mechanism. Finally, the theoretical and experimental results were compared. The research showed: (1) The theoretical results of the multi-tooth load distribution ratio were in good agreement with that of the experimental results, the maximum error between the theoretical value and the experimental value of the three-tooth joint was 17.44%, and the minimum error was only 2.35%; (2) The load distribution ratio of composite pre-tightened multi-tooth was uneven, for three-tooth joints, the values of load distribution ratio from large to small were: the first tooth, the third tooth and the second tooth.; (3) Multi-tooth load distribution ratio changed with the change of external load. The change of load distribution ratio was obvious in the early stage of loading, and tended to be gentle in the later stage of loading.

Diffusion-Weighted MR Imaging of Unicystic Odontogenic Tumors for Differentiation of Unicystic Ameloblastomas from Keratocystic Odontogenic Tumors

Yifeng Han,Xindong Fan,Lixin Su,Zhenfeng Wang 대한영상의학회 2018 Korean Journal of Radiology Vol.19 No.1

Objective: Differentiating unicystic ameloblastomas from keratocystic odontogenic tumors (KCOT) is necessary for the planning of different treatment strategies; however, it is difficult based on conventional CT and MR sequences alone. The purpose of this study was to investigate the utility of diffusion-weighted imaging (DWI) and apparent diffusion coefficients (ADCs) in the differentiation of the two tumors. Materials and Methods: We prospectively studied 40 patients with odontogenic cysts and tumors of the maxillomandibular region using conventional MR imaging and DWI. ADCs were measured using 2 b factors (500 and 1000). Results: Unicystic ameloblastomas (n = 11) showed free diffusion on DWI and a mean ADC value of 2.309 ± 0.17 x 10-3 mm2/s. KCOT (n = 15) showed restricted diffusion on DWI with a mean ADC value of 0.923 ± 0.20 x 10-3 mm2/s. The ADC values of unicystic ameloblastomas were significantly higher than those of KCOT (p < 0.001, Mann-Whitney U-test). An ADC cut-off value of 2.0 x 10-3 mm2/s to differentiate KCOT and unicystic ameloblastomas resulted in a 100% sensitivity and 100% specificity. Dentigerous cysts (n = 3) showed restricted diffusion on DWI and similar ADC values (1.257 ± 0.05 x 10-3 mm2/s) to those of KCOT. Conclusion: Diffusion-weighted imaging and ADC determination can be used as an adjuvant tool to differentiate between unicystic ameloblastomas and KCOT, although the ADC values of dentigerous cysts overlap with those of KCOT.

PRESSURE DROP CHARACTERISTICS OF R410A-OIL MIXTURE FLOW BOILING IN SMALL SMOOTH TUBES

YIFENG GAO,BIN DENG,GUOLIANG DING,HAITAO HU,XIANGCHAO HUANG 대한설비공학회 2010 International Journal of Air-Conditioning and Refr Vol.18 No.2

This study presents experimental frictional pressure drop for R410A/oil mixture flow boiling in small horizontal smooth tubes with inside diameters of 4.18 mm and 2.0 mm. Experimental conditions cover nominal oil concentrations from 0 to 5%. The test results show that the presence of oil enhances two-phase frictional pressure drop about 0–120% and 0–90% at present test conditions for 4.18 mm I.D. smooth tube and 2.0 mm I.D. smooth tube, respectively, and the enhanced effect is more evident at higher vapor qualities where the local oil concentrations are higher. A new correlation to predict the local frictional pressure drop of R410A/oil mixture flow boiling inside conventional size and small smooth tubes is developed based on local properties of refrigerant–oil mixture, and the experimental data of 4.18 mm I.D. and 2.0 mm I.D. smooth tubes and that of 6.34 mm I.D. smooth tube (Hu et al., 2008) are well-correlated with the new correlation.