Numerical Simulation and Experimental Study on the Interface Bonding of Stainless Steel Clad Plate

The rolling temperature and rate of thickness reduction directly affect the interface bonding quality, mechanical properties and microstructure of stainless steel clad plate. In order to obtain reasonable rolling process parameters, the multi-pass rolling processes of Q345R/316L stainless steel clad plate were simulated by the DEFORM software package. The distributions of stress, strain, and microstructure fields of the clad plate at different rolling temperatures and reduction rates were investigated. The bonding state of the interface was determined and the change rules governing the grain size of the rolled substrate layer also were analyzed. Vacuum hot-rolling tests were carried out to characterize the microstructure and mechanical properties. It was found that the higher the rolling temperature, the lower was the reduction rate needed to realize the interface bonding. However, too high temperatures produce a higher fraction of coarse grains, which affects the overall mechanical properties of the clad plate. It was concluded from the tests and numerical results that rolling temperature of 1150°C and reduction rate exceeding 50%, stainless allow one to produce steel clad plates with high interface bonding quality and excellent microstructure.Показано, что температура прокатки и степень обжатия оказывают влияние на силу сцепления на поверхности раздела, механические свойства и микроструктуру пластины, плакированной нержавеющей сталью. Процесс прокатки за четыре пропуска для пластины, плакированной нержавеющей сталью Q345R/316L, моделировали с помощью программы DEFORM, что позволило рассчитать его рабочие параметры. Исследовано распределение полей напряжений, деформаций и микроструктуры пластины при различной температуре прокатки и степени обжатия. Определена сила сцепления на поверхности раздела, проанализирован гранулометрический состав катаного подслоя при различных температурах. Проведены испытания образцов, полученных горячей вакуумной прокаткой, для оценки микроструктуры и механических свойств. Установлено, что чем выше температура прокатки, тем ниже степень обжатия, необходимая для обеспечения сцепления на поверхности раздела. Однако более высокие температуры вызывают увеличение доли грубых зерен, что оказывает влияние на механические свойства пластины. Экспериментально и численно показано, что температура прокатки в 1150°С и степень обжатия более 50% обеспечивают необходимую силу сцепления и качественную микроструктуру плакированной пластин

Novel low energy hydrogen–deuterium isotope breakthrough separation using a trapdoor zeolite

AbstractCs-chabazite, a type of zeolite with caesium counter-cations, possesses interesting gas separation properties due to a highly selective molecular “trapdoor” effect. Herein the use of this material for H2/D2 isotope separation is demonstrated. Isotope separation was achieved using breakthrough separation with a single pass through a packed bed at moderate temperatures (293K) and pressures (0.17MPa) when one species was in a sufficiently low concentration. The breakthrough separation curves were successfully modelled using the Thomas kinetic breakthrough model and the Yoon and Nelson kinetic breakthrough model, where working transferable kinetic rate constants were developed. Use of this material for hydrogen isotope separation would significantly lower the total energy demand compared with current hydrogen isotope separation techniques such as cryogenic distillation and is applicable to separating out low concentrations of D2 (0.0156%) present in standard grade H2

Voronoi-Delaunay analysis of normal modes in a simple model glass

We combine a conventional harmonic analysis of vibrations in a one-atomic model glass of soft spheres with a Voronoi-Delaunay geometrical analysis of the structure. ``Structure potentials'' (tetragonality, sphericity or perfectness) are introduced to describe the shape of the local atomic configurations (Delaunay simplices) as function of the atomic coordinates. Apart from the highest and lowest frequencies the amplitude weighted ``structure potential'' varies only little with frequency. The movement of atoms in soft modes causes transitions between different ``perfect'' realizations of local structure. As for the potential energy a dynamic matrix can be defined for the ``structure potential''. Its expectation value with respect to the vibrational modes increases nearly linearly with frequency and shows a clear indication of the boson peak. The structure eigenvectors of this dynamical matrix are strongly correlated to the vibrational ones. Four subgroups of modes can be distinguished

Pressure and linear heat capacity in the superconducting state of thoriated UBe13

Even well below Tc, the heavy-fermion superconductor (U,Th)Be13 has a large linear term in its specific heat. We show that under uniaxial pressure, the linear heat capacity increases in magnitude by more than a factor of two. The change is reversible and suggests that the linear term is an intrinsic property of the material. In addition, we find no evidence of hysteresis or of latent heat in the low-temperature and low-pressure portion of the phase diagram, showing that all transitions in this region are second order.Comment: 5 pages, 4 figure

Quantum interference in the fluorescence of a molecular system

It has been observed experimentally [H.R. Xia, C.Y. Ye, and S.Y. Zhu, Phys. Rev. Lett. {\bf 77}, 1032 (1996)] that quantum interference between two molecular transitions can lead to a suppression or enhancement of spontaneous emission. This is manifested in the fluorescent intensity as a function of the detuning of the driving field from the two-photon resonance condition. Here we present a theory which explains the observed variation of the number of peaks with the mutual polarization of the molecular transition dipole moments. Using master equation techniques we calculate analytically as well as numerically the steady-state fluorescence, and find that the number of peaks depends on the excitation process. If the molecule is driven to the upper levels by a two-photon process, the fluorescent intensity consists of two peaks regardless of the mutual polarization of the transition dipole moments. If the excitation process is composed of both a two-step one-photon process and a one-step, two-photon process, then there are two peaks on transitions with parallel dipole moments and three peaks on transitions with antiparallel dipole moments. This latter case is in excellent agreement with the experiment.Comment: 11 pages, including 8 figure

Thermal kaons production in the relativistic heavy ions collision

We study the thermal production of kaons in hot and dense symmetric and asymmetric hypernuclear matter in the context of the modified quark-meson coupling model. All the baryon species and kaons are treated as MIT bags that interact with each other via the scalar mesons $\sigma,\sigma^*$ and the vector mesons $\omega,\phi$ as well as the isovector meson $\rho$. Furthermore, in our calculations, we use realistic sets of hyperon-hyperon (or $YY$) interactions based on several versions of Nijmegen core potential models. We consider a system of strange hadronic matter and kaons but with zero total net strangeness of the system and conserved small negative fraction of the isospin-charge. We find strange baryons as well as kaons are produced abundantly when the temperature increases and approaches the critical temperature for the phase transition to the quark-gluon plasma. Our results show that the kaons are produced only thermally in the symmetric and asymmetric hypernuclear matter and there is no signature for the onset of kaon condensation in the relativistic heavy ions collision. The kaons appear in the system only by thermal production. However, when the system cools down strange hadrons could survive.Comment: 40 pages, 21 figure

Interaction of quasilocal harmonic modes and boson peak in glasses

The direct proportionality relation between the boson peak maximum in glasses, $\omega_b$, and the Ioffe-Regel crossover frequency for phonons, $\omega_d$, is established. For several investigated materials $\omega_b = (1.5\pm 0.1)\omega_d$. At the frequency $\omega_d$ the mean free path of the phonons $l$ becomes equal to their wavelength because of strong resonant scattering on quasilocal harmonic oscillators. Above this frequency phonons cease to exist. We prove that the established correlation between $\omega_b$ and $\omega_d$ holds in the general case and is a direct consequence of bilinear coupling of quasilocal oscillators with the strain field.Comment: RevTex, 4 pages, 1 figur

Final Report of the Fifth Meeting of Scientific Experts on Fish Stocks in the Central Arctic Ocean

This report provides a summary of the 5th meeting of scientific experts on Fish Stocks in the Central Arctic Ocean (FiSCAO) on October 24‐26, 2017, in Ottawa, Canada. At the request of the 10 parties negotiating on an agreement to prevent unregulated commercial fishing in the High Seas portion of the Central Arctic Ocean (CAO), participants of the 5th FiSCAO meeting were tasked with addressing four Terms of Reference, summarized below: ToR 1. Design a 1‐3 year long mapping program. ToR 2. Design a monitoring program. ToR 3. Identify human, financial, vessel/equipment resources needed for mapping and monitoring. ToR 4. Develop data collection, sharing, and hosting protocols that outline the details of what and how data shall be collected, shared, and hosted for consideration by the Parties. The 5th FiSCAO meeting included scientific representatives from seven states including Canada, the People's Republic of China, the European Union, Iceland, the Republic of Korea, the Kingdom of Norway and the United States of America. The meeting also included representatives from the International Council for the Exploration of the Sea (ICES), the North Pacific Marine Science Organization (PICES) and the Arctic Council’s Protection of the Arctic Marine Environment (PAME) and Conservation of Arctic Flora and Fauna (CAFF) working groups. The report summarizes the elements for collecting baseline data (i.e., a mapping program) in the high seas CAO to achieve the goals of documenting species distributions, relative abundances and key ecosystem parameters (ToR 1). The mapping program describes the priority areas to sample, the types of data to collect and possible data collection approaches to employ. Participants emphasized that existing planned surveys are very limited, and that significant dedicated resources will be required to implement the mapping program. The report outlines a strategy for monitoring indicators of fish stocks and ecosystem components (ToR 2). The report includes a list of existing monitoring programs and a prioritized list of indicators to detect environmental change in the high seas CAO. Further refinement of a monitoring program will use information from the mapping program (ToR 1). Participants emphasized the need to begin monitoring as soon as possible and that additional research is required to operationalize monitoring indicators. The report summarizes the preliminary cost estimates (ToR 3) to implement a mapping program to collect data in the high seas portion of the CAO using a vessel of opportunity and in the Pacific Gateway region of the CAO using an independently‐organized survey. Cost implications for the monitoring program and other scientific activities are also listed (e.g., data analysis, data management). The report includes a draft data sharing policy as the foundation for a future data sharing protocol, including the technical specifications for data sharing (ToR 4). The development of the data sharing protocol will require negotiation and legal review among the participating states. A data management and data sharing pilot study on a CAO fish database is suggested to test a framework

On the Nature and Genesis of EUV Waves: A Synthesis of Observations from SOHO, STEREO, SDO, and Hinode

A major, albeit serendipitous, discovery of the SOlar and Heliospheric Observatory mission was the observation by the Extreme Ultraviolet Telescope (EIT) of large-scale Extreme Ultraviolet (EUV) intensity fronts propagating over a significant fraction of the Sun's surface. These so-called EIT or EUV waves are associated with eruptive phenomena and have been studied intensely. However, their wave nature has been challenged by non-wave (or pseudo-wave) interpretations and the subject remains under debate. A string of recent solar missions has provided a wealth of detailed EUV observations of these waves bringing us closer to resolving their nature. With this review, we gather the current state-of-art knowledge in the field and synthesize it into a picture of an EUV wave driven by the lateral expansion of the CME. This picture can account for both wave and pseudo-wave interpretations of the observations, thus resolving the controversy over the nature of EUV waves to a large degree but not completely. We close with a discussion of several remaining open questions in the field of EUV waves research.Comment: Solar Physics, Special Issue "The Sun in 360",2012, accepted for publicatio