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Convergence, stability and robustness analysis of the OFEX controller for high-speed networks

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Control Theory and Technology 2016年第2期14卷 122-139页

作者： Jungang LIU Oliver w. w. YANG School of Electrical Engineering and Computer Science University of Ottawa Ottawa KI N 6N5 Canada

The OFEX （Optimal and Fully EXplicit） rate controller is able to provide not only the optimal bandwidth allocation but also the fully explicit congestion signal to sources. It exercises link-wise proportional fairness and network-wise max-min fairness, which enables the controller to feed the congestion signal back from the most congested link, instead of using the network- wise proportional fairness which feeds back the congestion signal summed along a flow path. As a result, the OFEX controller overcomes the drawbacks of the relatively explicit controllers that 1） bias the multi-bottlenecked users in terms of their source sending rate and convergence speed, 2） are not adaptable to varying link bandwidth and 3） can potentially incur large queue size upon congestion. In this paper, we first prove that the OFEX controller can converge to its equilibrium at least as fast as a geometric series in a link. Then we analyze the system stability with time delay in a single bottleneck network and show that the OFEX controller can achieve local stability under certain conditions. Besides, the robustness analysis of the OFEX controller shows how the dynamics of link bandwidth may affect the revenue of a link. Finally, with the OPNET modeler, we evaluate the performances of the OFEX controller and verify its effectiveness.

关键词： Fully explicit convergence stability time delay robustness performance evaluation

GROwTH KINETICS OF SINGLE INCLUSION PARTICLE IN MOLTEN MELTS

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Acta Metallurgica Sinica(English Letters) 2007年第2期20卷 129-138页

作者： B.w. Zhang B.w. Li Department of Materials and Metallurgy Inner Mongolia University of Science and Technology Baotou 014010 China

On the basis of the single-particle framework, a new theory on inclusion growth in metallurgical melts is developed to study the kinetics of inclusion growth on account of reaction and collision. The studies show that the early growth of inclusion depends on reaction growth and Brawnian motion collision, and where the former is decisive, the late growth depends on turbulence collision and Stokes＇ collision, and where the former is dominant; collision growth is very quick during the smelting process, lessened in the refining process, but nearly negligible in the continuous casting process.

关键词： inclusion growth reaction collision kinetics

Effect of compressibility on the hypervelocity penetration

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Acta Mechanica Sinica 2018年第1期34卷 82-98页

作者： w.J.Song X.w.Chen P.Chen Department of Mechanics and Engineering Science College of Engineering Peking University Advanced Research Institute for Multidisciplinary Science Beijing Institute of Technology The State Key Lab of Explosion Science and Technology Beijing Institute of Technology Centre for Applied Physics and Technology (CAPT) Peking University

we further consider the effect of rod strength by employing the compressible penetration model to study the effect of compressibility on hypervelocity ***, we define different instances of penetration efficiency in various modified models and compare these penetration efficiencies to identify the effects of different factors in the compressible model. To systematically discuss the effect of compressibility in different metallic rod-target combinations, we construct three cases, i.e., the penetrations by the more compressible rod into the less compressible target, rod into the analogously compressible target, and the less compressible rod into the more compressible target. The effects of volumetric strain, internal energy, and strength on the penetration efficiency are analyzed simultaneously. It indicates that the compressibility of the rod and target increases the pressure at the rod/target interface. The more compressible rod/target has larger volumetric strain and higher internal energy. Both the larger volumetric strain and higher strength enhance the penetration or anti-penetration ability. On the other hand, the higher internal energy weakens the penetration or anti-penetration ability. The two trends conflict, but the volumetric strain dominates in the variation of the penetration efficiency, which would not approach the hydrodynamic limit if the rod and target are not analogously compressible. However, if the compressibility of the rod and target is analogous, it has little effect on the penetration efficiency.

关键词： Compressibility Hypervelocity penetration Equation of state(EOS) Shockwave Bernoulli equation

Glass-forming Ability and Corrosion Resistance of Zr—Cu—Al—Co Bulk Metallic Glass

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Journal of Materials Science & Technology 2016年第4期32卷 349-354页

作者： w.Zhou w.P.weng J.X.Hou Shagang School of Iron and Steel Soochow University

Investigations were carried out to examine the effects of Co addition on the glass-forming ability （GFA） and corrosion resistance of Zr46Cu46AI8 bulk metallic glass in chloride-containing solution. It is found that the GFA of （Zr46Cu46Al8）100-xCox （x = 0, 1, 2, and 4 at.%） alloys reduces with the increase in Co content and correlates well with the parameters, such as the supercooled liquid region width ATx, the reduced glass transition temperature Trg and γ. The corrosion resistance is however found to be enhanced with the in- crease in Co concentration. The addition of Co causes the enrichment of Zr and Al, but depletes Cu in the surface films, which effectively enhances the corrosion potential and lowers the corrosion current density.

关键词： Bulk metallic glassCo-additionGlass-forming abilityCorrosion resistance

New Development of Acid Regeneration in Steel Pickling Plants

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Journal of Iron and Steel Research International 2008年第4期15卷 1-6页

作者： w F Kladnig ICC Chemical Consulting Vienna A-1193 Austria

For acid pickling heat treated mild steel and steel products, up to the middle of the last century, sulfuric acid was primarily in use, which has been replaced stepwise by hydrochloric acid since the sixties. During this time, the pickling of high alloyed steel with hydrofluoric acid or mixtures for hydrofluoric acid together with nitric acid has also been applied on industrial scale. The technologies used by several plant contractors hereby show considerable differences in their engineering. The study provides a survey of the progress in the state of art of regeneration technology as well as the use of different *** media in the form of a review on existing technologies as well as improvements done within the recent years in the area.

关键词： pickling mild steel high alloyed steel acid recycling technology global emission standard treatment of stack gas

RESEARCH AND DEVELOPMENT OF NEw SUPERALLOY REMELTING PROCES

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Acta Metallurgica Sinica(English Letters) 2005年第1期18卷 81-90页

作者： w.Xie BaosteelGroupShanghaiNo.5SteelCo. Ltd.Shanghai200940China

Shanghai No.5 Steel Co., Ltd. has recently introduced a set of 5-ton protective atmosphere elec-troslag remelting furnace and a set of 10-ton helium-cooling vacuum arc remelting furnace, both of them are the first one of its kind in China. with these equipment, remelting processes about alloy GH4169, CH2132 and GH738 were researched, the process of producing alloy GH4169 by VIM+VAR+ESR triplex-process was developed, and their effects were discussed.

关键词： superalloy argon shield ESR helium cooling VAR VIM+VAR+ESR

Hormone naive prostate cancer： predicting and maximizing response intervals

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Asian Journal of Andrology 2015年第6期17卷 929-935,I0007,I0008页

作者： Judd w Moul Division of Urology Department of Urology Duke Cancer Institute Duke South Duke University Medical Center Durham NC 27710 USA.

Hormone naive advanced prostate cancer is subdivided into two disease states： biochemical recurrence and traditional M 1 （metastatic） prostate cancer and characterized by no prior hormonal therapy or androgen deprivation therapy （ADT）. In biochemical recurrence/ prostate-specific antigen （PSA） recurrence, men should be risk-stratified based on their PSA doubling time, the Gleason score and the timing of the recurrence. In general, only men who are at high risk should be considered for early/immediate ADT although this is best done using shared decision with the patient. The type of ADT to be used in biochemical recurrence ranging from oral-only peripheral blockade （peripheral androgen deprivation） to complete hormonal therapy （combined androgen blockade [CAB]） remains in debate owing to lack of randomized controlled trials （RCT）. However, there is good RCT support for use of intermittent hormonal therapy （IHT）. There is also limited research on biomarker response （PSA and testosterone decline） to predict prognosis. On the other hand, in the setting of M1 hormone naive prostate cancer, there are many more RCT＇s to inform our decisions. CAB and gonadotrophin-releasing hormone antagonists perhaps provide a slight efficacy advantage while IHT may be slightly inferior with minimal M1 disease. The PSA nadir at 7 months after starting ADT is a powerful prognostic tool for M1 patients. There is growing recognition that serum testosterone （T） control while on ADT is linked to the development of castrate-resistant prostate cancer. Especially for a M 1 patient, maintaining a serum T below 20-30 ng d1-1 prolongs the response to ADT. Novel oral agents （abiraterone and enzalutamide） may soon find use in hormone naive disease and may alter the treatment landscape. Despite over 75 years of experience with ADT, many questions remain, and the field continues to evolve.

关键词： androgen deprivation therapy cancer gonadotrophin-releasing hormone antagonists hormonal therapy luteinizing hormone-releasing hormone agonists prostate prostate-specific antigen testosterone

Structural behaviour of fibre metal laminates subjected to a low velocity impact

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Science China(Physics,Mechanics & Astronomy) 2011年第6期54卷 1168-1177页

作者： CANTwELL w J University of Liverpool Department of Engineering

Structural impact tests were first presented to cover typical fibre metal laminates (FMLs) subjected a low velocity projectile impact,which produced the corresponding load-displacement traces and deformation/failure modes for the validation of numerical *** element (FE) models were then developed to simulate the impact behaviour of FMLs *** aluminium (alloy grade 2024-0) layer was modelled as an isotropic elasto-plastic material up to the on-set of post failure stage,followed by shear failure and tensile failure to simulate its failure *** glass fibre laminate (woven glass-fibre reinforced composite) layer was modelled as an orthotropic material up to its on-set of damage,followed by damage initiation and evolution using the Hashin *** damage initiation was controlled by failure tensile and compressive stresses within the lamina plane which were primarily determined by *** damage evolution was controlled by tensile/compressive fracture energies combined with both fibre and *** FE models developed for the 2/1,3/2 and 4/3 FMLs plates made with 4-ply and 8-ply glass fibre laminate cores were validated against the corresponding experimental *** correlation was obtained in terms of load-displacement traces,deformation and failure *** validated models were ready to be used to undertake parametric studies to cover FMLs plates made with various stack sequences and composite cores.

关键词： damage Hashin criterion finite element impact FMLs progressive failure

Lateral distributions of streamwise velocity in compound channels with partially vegetated floodplains

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Science China(Technological Sciences) 2009年第11期52卷 3357-3362页

作者： KNIGHT Donald w School of Civil Engineering The University of Birmingham Birmingham B15 2TT UK

Natural rivers are commonly characterized by a main channel for primary flow conveyance and a floodplain, often partially covered with vegetation such as shrubs or trees, to carry extra flow during floods. The hydraulic resistance due to vegetation on the floodplain typically causes a further reduction of flow velocity and increases the velocity difference between the main channel and the floodplain. As a consequence a strong lateral shear layer leads to the exchange of mass and momentum between the main channel and floodplain, which in turn affects the overall channel conveyance and certain fluvial processes. The prediction of the lateral velocity distribution is important for many flood alleviation schemes, as well as for studies on sediment transport and dispersion in such channels. The present paper proposes a method for predicting the depth-averaged velocity in compound channels with partially vegetated floodplains, based on an analytical solution to the depth-integrated Reynolds-Averaged Navier-Stokes equation with a term included to account for the effects of vegetation. The vegetation is modelled via an additional term in the momentum equation to account for the additional drag force. The method includes the effects of bed friction, drag force, lateral turbulence and secondary flows, via four coefficients f, CD, λ & Γ respectively. The predicted lateral distributions of depth-averaged velocity agree well with the experimental data. The analytical solutions can also be used to predict the distribution of boundary shear stresses, which adds additional weight to the method proposed.

关键词： vegetation compound channel floodplain velocity