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THRESHOLD CONDITION FOR CHOCKING IN OPEN CHANNELS AND EXCAVATION OF TAILRACE

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Journal of Hydrodynamics 2005年第2期17卷 164-170页

作者： nihan-gen LIUYa-kun StateKeyLaboratoryofCoastalandOffshoreEngineering DalianUniversityofTechnologyDalian116024China

On the basis of energy and continuity equations a general threshold condition for chocking in open channels is obtained and a representation in terms of the Froude number at the upstream section and other parameters is given to predict whether the chocking phenomenon occurs or not at the downstream section. From the general threshold condition for chocking the limit contraction ratios of the channel width are introduced for both with and without the energy losses and a criterion for excavation of the tailrace to avoid chocking is derived. An example shows that using these criterion and the representation proposed for calculating flow depth it is very easy to determine the scheme of the excavation of the open channels.

关键词： threshold condition for chocking limit contraction ratio of channel width criterion for excavation of open channels

TRANSITIONAL FLOW IN CHANNEL JUNCTIONS

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Journal of Hydrodynamics 2004年第4期16卷 464-467页

作者： nihan-gen LIUYa-kun StateKeyLaboratoryofCoastalandOffshoreEngineering DalianUniversityofTechnologyDalian116024China

On the basis of energy and continuity equations a simple one-dimensionalformulation was proposed to predict the transitional flow at an open-channel junction. An empilicalrelation between the junction losses, the junction angle, and the discharge ratio was suggestedwhich agrees well with the experimental results. The results calculated by the present formulationfor the depth ratio were compared with the results of earlier one-dimensional formulations andexperiments. It is found that the present results coincide better with experiments than those ofothers.

关键词： open channel junctions energy losses transitional flow

EFFECT OF AERATOR ON HYDRAULIC DRAG ACTING ON A CHUTE

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Journal of Hydrodynamics 2005年第1期17卷 34-42页

作者： nihan-gen LIXin ZHOUJing JINQiao StateKeyLaboratoryofCoastalandOffshoreEngineering DalianUniversityofTechnologyDalian116024China

The formulae used to calculate the friction in the non uniform flow chute were examined with the experimental data, and the results show that the accuracy of the formula is enough for engineering applications. A comparison between the results of friction respectively from the uniform flow assumption and the non uniform flow approximation indicates that the former is an order of magnitude larger than the latter in the case of steep chute. The hydraulic drag on a steep chute with aerators was measured on the hydraulic model directly and the coefficient of the aerator effect on the drag was obtained. The variation patterns of the wall shear just downstream of the aerators were investigated and the mechanism of the increase in the drag by aerator were analyzed qualitatively with the measured water depths just downstream the aerators.

关键词： overflow chute aerator wall shear hydraulic drag

Additive manufacturing of energetic materials:Tailoring energetic performance via printing

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Journal of Materials Science & Technology 2022年第32期127卷 29-47页

作者： nihan Chen Chunlin He Siping Pang Experimental Center of Advanced Materials School of Materials Science&EngineeringBeijing Institute of TechnologyBeijing 100081China Yangtze Delta Region Academy of Beijing Institute of Technology Jiaxing 314019China Chongqing Innovation Center Beijing Institute of TechnologyChongqing 401120China State Key Laboratory of Explosion Science and Technology Beijing Institute of TechnologyBeijing 100081China

Additive manufacturing(AM),also called three-dimensional(3D)printing,has been developed to obtain energetic materials within the past decade.3D printing represents a family of flexible manufacturing techniques that enable fast and accurate fabrication of structures with complex 3D features and a broad range of sizes,from submicrometer to several *** methods have already been explored,including templating,melting extrusion,inkjet printing and electrospray *** was demonstrated that the structure achieved by AM could be used to manipulate the reactivity of energetic or reactive materials by changing the flow of gases and entrained particles via *** employing different AM techniques,energetic materials with controllable nanostructures and uniformly dispersed ingredients can be *** is exciting to tailor the energy release without defaulting to change the formulation of the conventional *** combustion and mechanical properties of conventional energetic materials can be retained at the same *** this review,the preparation and characterization of AM energetic materials that have been developed in the last decade are *** AM techniques used in the fabrication of energetic materials are compared and *** particular,formulations of energetic materials applied in AM,metallic fuels,binders and energetic fillers and their advantages in terms of combustion efficiency and other properties are proposed.

关键词： Additive manufacturing Energetic materials Nanothermite Propellant

A note on generalized Lie derivations of prime rings

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Frontiers of Mathematics in China 2017年第1期12卷 247-260页

作者： nihan Baydar YARBIL Nurcan ARGAC Department of Mathematics Science Faculty Ege University 35100 Bornova Izmir Turkey

Let R be a prime ring of characteristic not 2, A be an additive subgroup of R, and F, T, D, K： A →R be additive maps such that F（[x, y]） = F（x）y - yg（x） - T（y）x ＋ xD（y） for all x, y ∈ A. Our aim is to deal with this functional identity when A is R itself or a noncentral Lie ideal of R. Eventually, we are able to describe the forms of the mappings F, T, D, and K in case A = R with deg（R）〉 3 and also in the case A is a noncentral Lie ideal and deg（R）〉 9. These enable us in return to characterize the forms of both generalized Lie derivations, D-Lie derivations and Lie centralizers of R under some mild assumptions. Finally, we give a generalization of Lie homomorphisms on Lie ideals.

关键词： Prime ring derivation generalized derivation generalized Lie derivation functional identity generalized polynomial identity

Orientation in Nematic Liquid Crystals Doped with Orange Dyes and Effect of Carbon Nanoparticles

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Chinese Journal of Chemical Physics 2010年第3期23卷 368-372,I0002页

作者： Ahmet Alicilar Fatih Akkurt nihan Kaya 加辛大学工学院化学工程系马尔泰佩安卡拉06570

Some properties of nematic liquid crystal E7 doped with two disperse orange dyes used together and effect of addition of carbon nanoparticles （single walled carbon nanotube or fullerene C60） on them were studied. Two dyes （disperse orange 11 and 13） having high solubility and order parameter were used as co-dopants. A notable increase in order parameter was obtained comparing to that of liquid crystal doped with single dye. When carbon nanoparticles were used as dopant, a decrease in order parameter was observed at low temperatures while it increased at high temperatures. When applied voltage changed, the order parameter abruptly increased in its threshold value and saturated in higher voltages as expected. An appreciable change in textures was not observed with addition of dopants. This addition gave rise to an increase in nematic-isotropic phase transition temperatures compared with that of pure liquid crystal.

关键词： Liquid crystal Disperse orange dye Carbon nanoparticle Order parameter

Investigation of Single-Wall MoS_2 Monolayer Flakes Grown by Chemical Vapor Deposition

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Nano-Micro Letters 2016年第1期8卷 70-79页

作者： nihan Kosku Perkgoz Mehmet Bay Department of Electrical and Electronics Engineering Faculty of Engineering Anadolu University

Recently, two-dimensional monolayer molybdenum disulfide(MoS_2), a transition metal dichalcogenide, has received considerable attention due to its direct bandgap, which does not exist in its bulk form, enabling applications in optoelectronics and also thanks to its enhanced catalytic activity which allows it to be used for energy harvesting. However,growth of controllable and high-quality monolayers is still a matter of research and the parameters determining growth mechanism are not completely clear. In this work, chemical vapor deposition is utilized to grow monolayer MoS_2 flakes while deposition duration and temperature effect have been systematically varied to develop a better understanding of the MoS_2 film formation and the influence of these parameters on the quality of the monolayer flakes. Different from previous studies, SEM results show that single-layer MoS_2 flakes do not necessarily grow flat on the surface, but rather they can stay erect and inclined at different angles on the surface, indicating possible gas-phase reactions allowing for monolayer film formation. We have also revealed that process duration influences the amount of MoO_3/MoO_2 within the film network. The homogeneity and the number of layers depend on the change in the desorption–adsorption of radicals together with sulfurization rates, and, inasmuch, a careful optimization of parameters is crucial. Therefore, distinct from the general trend of MoS_2 monolayer formation, our films are rough and heterogeneous with monolayer MoS_2 nanowalls. Despite this roughness and the heterogeneity, we observe a strong photoluminescence located around 675 nm.

关键词： Monolayer Chemical vapor deposition Two-dimensional materials Molybdenum disulfide(MoS2)

The impact of autophagy in spermiogenesis

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Asian Journal of Andrology 2017年第6期19卷 617-618页

作者： nihan Ozturk Klaus Steger Undraga Schagdarsurengin Clinic of Urology Pediatric Urology and AndrologySection Molecular Andrology Justus-Liebig-UniversityGiessen Schubertstrasse 81 35392 GiessenGermany.

Autophagy is an evolutionarily .conserved self-digestion process whichis essential to keep basal homeostasis in a cell. During this process, degradation and recycling of many cytoplasmic components including the long-lived, unnecessary or aggregated proteins and damaged organelles is achieved through lysosomal machinery. Autophagy has a critical role for lower eukaryotic organisms such as yeast to survive and adapt to nutrient starvation conditions. In addition to this primary function, autophagy appears as a crucial mechanism for cell differentiation and development enabling the cells to modify their content and morphology in response to environmental and hormonal cues. A recent study by Shang et all shed more light on the molecular mechanisms of how autophagy regulates spermiogenesis.

关键词： impact autophagy spermiogenesis

Analysis of the Relationship Between Perceived Security and Customer Trust and Loyalty in Online Shopping

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Chinese Business Review 2011年第11期10卷 990-997页

作者： nihan Ozguven Dokuz Eylul University lzmir Turkey

Advancements in the internet technology triggered a line of developments in the field of marketing. As an alternative to the conventional shopping, online shopping over the internet has gained substantial share of retail market. Customers get used to this new shopping venue and nowadays prefer it more and more according to the researchers, ten percent of the global population now uses internet for shopping. In this research, the author explored the relationship between the security measures implemented by a company, very active in the online shopping domain, and the customer trust and loyalty on the online services provided by this company. Findings of this research are based on survey data analyzed in SPSS. This research supports the existence of a relationship between the security of a company＇s website and customer trust and loyalty on the online services of this company When the perception of security measures improves, customer trust and loyalty increases accordingly

关键词： customers customer trust perceived security loyalty online shopping websites