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In this work, 0.3 wt% Mn-doped BaTiO 3 - x Bi(Mg 0.5 Hf 0.5)O 3 (BT- x BMH, x = 0.05–0.20) lead-free ceramics were prepared by solid-state reaction method. The structure, dielectric properties, energy-storage characteristics, and pulsed charge/discharge performance were investigated thoroughly. It was found that BMH doping leads to a phase-change from tetragonal to pseudocubic phase with enhanced relaxor behavior. Mn-doping can effectively suppress the leakage current via the associating of Mn2+ ions with oxygen vacancies. The sample of x = 0.15 displays superior dielectric thermal stability meeting the EIA-X9R standard. An optimal recoverable energy-storage density W rec = 3.1 J/cm3 at 255 kV/cm with boosted energy-storage efficiency η = 92.4% were realized in the sample. Moreover, this sample displays superior thermal and frequency stability with large power density (P D ∼ 80.3 MW/cm3) and ultra-fast transient discharge time (t 0.9 –34 ns). These characteristics suggest that the ceramic holds highly promising for high temperature capacitors and energy-storage applications. [ABSTRACT FROM AUTHOR]

Slip flow in a rectangular cavity is studied. Using slip eigenfunctions, an exact series solution is found for a lid sliding longitudinally. For a transversely sliding lid, the stream function for Stokes flow is determined by a new set of slip eigenfunctions and supplemented by point match on the boundary. It is found that slip has considerable effect on the flow properties. Analyses of the region very close to the corner of the velocity discontinuity show the stress singularity of no-slip flow can be eliminated by slip for both longitudinal flow and transverse flow, except when the latter corner is a right angle. [ABSTRACT FROM AUTHOR]

The aim of this work is to investigate the fundamentals of dislocation-particle interactions in a Mg-1%Mn-1%Nd (wt.%) (MN11) alloy in order to better understand the limited precipitation strengthening exhibited by this material. A combined approach including micromechanical testing, slip trace analysis, and high resolution transmission electron microscopy (TEM) is put in place to analyze the interaction between basal and non-basal dislocations with the Mg-Nd plate precipitates that are characteristic of the investigated alloy. It is shown that basal dislocations can easily shear the precipitates, both when their long axis lays parallel and perpendicular to the matrix c axis. This is attributed to the high coherency between the matrix and the particles, which is characterized in detail. It is additionally shown that pyramidal ⟨c + a⟩ dislocations, on the contrary, interact with precipitates both in the form of shearing along the precipitate pyramidal planes, as well as by Orowan looping. This study reveals that pyramidal dislocations are able to shear the plate precipitates along pyramidal planes when there is a good alignment between the slip plane of the incoming matrix dislocation and the outgoing precipitate pyramidal plane. Otherwise pyramidal dislocations sliding on matrix planes with small geometric compatibility with the precipitate pyramidal planes bypass these particles by an Orowan looping mechanism. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The study of the flow in a tube flattened by parallel plates is important in the transport of fluids in laterally restricted conduits. The unsteady (starting and oscillatory) flows are solved using the method of eigenfunction superposition. The necessary eigenvalues and eigenfunctions of the Helmholtz equation are determined, for the first time, by accurate one-region or two-region point match collocations. The starting times for the starting transient depends on the aspect ratio of the duct. For oscillatory flows, the velocity maximum shifts towards the walls at higher normalized frequencies. [ABSTRACT FROM AUTHOR]

• Explicit solutions are found for transient natural convection in ducts. • Eigenfunction superposition method is well suited for fully-developed flow. • Rise time to steady state depends on the first eigenvalue of the Helmholtz equation. This paper models the transient natural convection problem for the hydrodynamical and thermal fully-developed open vertical ducts. The powerful method of eigenfunction superposition yields analytic solutions for general duct cross sections. It is found that the induced flow rate approaches a constant in the steady state, but the transient depends on the Prandtl number (Pr). The rise time to reach 95% of steady state is 3 / (Pr λ 1) if Pr < 1, and is 3/λ 1 if Pr > 1, where λ 1 is the lowest eigenvalue of the Helmholtz equation. The theory is then applied to the circular, semi-circular, rectangular and equilateral triangular ducts. For low Pr at small times, the transient induced velocity is larger in the velocity boundary layer near the walls but the maximum velocity is near the corners of the duct. [ABSTRACT FROM AUTHOR]

This paper provides the physical design of a low-energy proton irradiation facility for space radiation effect research, based on an existing linear accelerator (linac)-based compact neutron source. The beam requirement of the low-energy proton irradiation consists of a proton flux range of 1 0 8 – 1 0 9 p ∕ cm 2 ∕ s with a nonuniformity of less than 10% in the target diameter area of 2 cm, and optional proton energies of < 1 MeV to 13 MeV. Based on the existing high-current proton linac, the flux range and nonuniformity of the proton beam at the target can be achieved by inserting beam apertures, adjusting quadrupole fields to expand the beam size, and decreasing the repetition rate of the beam pulse. To measure the energy distribution of the protons, one CdZnTe detector can be employed. The above approach is performed on the physical design of the low-energy proton facility for the Compact Pulsed Hadron Source at Tsinghua University. The proton flux at the target can be reduced from 6. 2 × 1 0 14 p ∕ cm 2 ∕ s to 1. 2 × 1 0 8 − 3. 0 × 1 0 9 p ∕ cm 2 ∕ s , and proton energies of 0.56, 5.0, 8.2, and 10.5 MeV can be obtained separately with the energy degrader (aluminum) thicknesses of 75, 800, 550, and 300 μ m. Irradiation nonuniformity is less than 10%. Energy spread is less than 10% for the proton energy of 3.0, 5.0, 8.2, and 10.5 MeV, except for the low energy of 0.56 MeV. [ABSTRACT FROM AUTHOR]

• Instead of Nusselt number, Sparrow number appears in the dimensionless governing equations by using equilibrium thermal diffusivity. • The Sparrow number is interpreted as the equilibrium conduction thermal resistance to the convection thermal resistance in the pores. • A good agreement between the pore scale and volume averaged results for the working fluid of water and air is observed. • A chart is presented in terms of Sparrow number, solid thermal diffusivity and thermal capacitance to estimate the local thermal equilibrium condition. The local thermal non-equilibrium condition for a porous medium with closed cells under unsteady state heat transfer is analyzed. Although the fluid circulates in the closed pores due to the buoyancy effect, the volume averaged velocity for a closed pore is zero causing excluding of the continuity and momentum equations from the volume averaged governing equations. The volume averaged governing equations are non-dimensionalized by using the equilibrium thermal diffusivity and Sparrow number appears in the dimensionless governing equations automatically. The Sparrow number is interpreted as the equilibrium conduction thermal resistance to the convection thermal resistance for the entire domain. For the high values of Sparrow number (such as 1000), the convection heat transfer resistance is considerably smaller than the heat conduction resistance resulting in high possibility of the local thermal equilibrium. Dimensionless governing equations show that four dimensionless parameters as porosity, Sparrow number, solid (or fluid) dimensionless thermal capacitance and thermal conductivity play important roles on the prediction of the local thermal non-equilibrium state in a closed cell porous medium. A chart for the prediction of local thermal non-equilibrium is presented for Sparrow number of 1, 50, 100 and 500. Furthermore, a pore scale study for a closed cell porous medium with working fluids as water and air is performed. A good agreement between the pore scale and volume averaged results is observed. The obtained pore scale results support the results of the volume averaged parametric study and also the suggested chart for the prediction of local thermal non-equilibrium state. [ABSTRACT FROM AUTHOR]

Abstract Effects of coverage layer on electrochemical corrosion behaviour and pitting morphologies of Mg-Al-Mn alloy subjected to massive laser shock peening (LSP) treatment were investigated by potentiodynamic polarisation test, electrochemical impedance spectroscopy (EIS), and scanning electron microscope (SEM) observations. Microstructures of Mg-Al-Mn alloy subjected to massive LSP treatment were also characterized. Results showed that LSP induced an obvious improvement in electrochemical corrosion resistance with increasing coverage layer. Even in a higher corrosive solution concentration, LSP could still prevent corrosion to some extent. The improvement in electrochemical corrosion resistance was due to the grain refinement and compressive residual stress induced by massive LSP treatment. Finally, the influence mechanism of the coverage layer on electrochemical corrosion behaviour of Mg-Al-Mn alloy was revealed. Graphical abstract Schematic illustration of the coverage layer on the electrochemical corrosion behaviour in NaCl solution. (a) The as-received, (b) the LSP-1, and (c) the LSP-4 specimen. Image 1 Highlights • LSP generated an obvious improvement in electrochemical corrosion resistance. • The increment of the coverage layer led to a stronger corrosion resistance. • Even in a more corrosive solution, LSP still prevent corrosion to a certain extent. • Influence mechanism of LSP coverage layer on corrosion resistance was revealed. [ABSTRACT FROM AUTHOR]

The mechanical behavior of nanotwinned Cu was studied through indentation creep and constant strain rate indentation tests from 25 °C to 200 °C. The results showed an enhanced strain rate sensitivity of nanotwinned Cu with temperature, which was higher than that found in coarse-grained Cu. Transmission electron microscopy revealed the same deformation mechanism in the whole temperature range: confined dislocation slip between coherent twin boundaries and formation of dislocation pile-ups at the coherent twin boundaries. The mechanisms responsible for large increase in strain rate sensitivity of nanotwinned Cu with temperature were discussed to the light of experimental observations. [ABSTRACT FROM AUTHOR]

Herein, a report on non-noble metal (Ni, Co, Cu, and their combination) nanoparticles (NPs) supported on TiO 2 spheres as catalysts for hydrogen generation via hydrolysis of ammonia borane (NH 3 BH 3 , AB) is provided. The TiO 2 spheres were prepared through a template method by using polystyrene (PS). The metallic nanoparticles were synthesized by a redox replacement reaction. The structure, morphology, and chemical composition of the obtained samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) equipped with energy dispersive X-ray spectroscopy (EDX), and X-ray Photoelectron Spectroscopy (XPS). The characterization results showed that the metallic nanoparticles were well dispersed on the TiO 2 supports. The catalytic activity toward the hydrolysis of AB was found to correlate well with the amount of metallic elements in catalysts while for the multicomponent phases, a synergistic effect was noticed. Theoretical calculations revealed that Ni, Co, and Cu atoms significantly influenced the electronic behavior of TiO 2 and thereby, the catalytic properties of the materials. [ABSTRACT FROM AUTHOR]

The de-/rehydrogenation features of the 6LiBH 4 /SrF 2 reactive hydride system have been systematically investigated. It was found that the thermal stability of LiBH 4 can be reduced markedly by combining it with SrF 2 . Dehydrogenation of the 6LiBH 4 /SrF 2 system proceeds via the 6LiBH 4 + SrF 2 → SrB 6 + 2LiF + 4LiH + 10H 2 reaction, which involves SrH 2 as the intermediate product. The dehydrogenation enthalpy change was experimentally determined to be 52 kJ/mol H 2 based on the P–C isotherm analysis. For rehydrogenation, LiBH 4 and SrF 2 were regenerated along with LiSrH 3 at 450 °C under ∼8 MPa hydrogen pressure; thus, approximately 5.2 wt% of hydrogen can be released during the second dehydrogenation process. [ABSTRACT FROM AUTHOR]

The aim of this study was to investigate the effect of dietary high non-phytate phosphorus (NPP) level on the growth performance and metabolism of Ca and P in Lion-head geese during starter and grower-finisher periods. A total of 384 goslings at d 1 and 240 geese at d 29 were divided into 3 treatments with 4 replicate pens each treatment for Exp. 1 (the starter period for d 1–21) and Exp. 2 (the grower-finisher period for d 29–72), respectively. The 3 supplemental NPP levels (Ca: NPP ratio) in diets were 0.40% (2.38), 0.60% (1.58) and 0.80% (1.19) for Exp. 1 and were 0.30% (2.83), 0.50% (1.70) and 0.70% (1.21) for Exp. 2. In Exp. 1, final body weight, average daily gain and average daily feed intake of goslings fed a diet containing 0.80% NPP (Ca: NPP ratio,1.19) were decreased ( P  < 0.05) compared to birds fed a diet containing 0.60% NPP (Ca: NPP ratio, 1.58) at the starter period, with no difference ( P  > 0.05) between the two diets containing NPP of 0.40% (Ca: NPP ratio, 2.38) and 0.80% (Ca: NPP ratio,1.19). At d 21 of goslings, the concentrations of Ca, P, parathyroid hormone and bone gla-protein, and alkaline phosphatase activity in serum were decreased ( P <  0.05) linearly in response to the increasing NPP level and decreasing Ca: NPP ratio in diets. At d 72 of geese, tibia bone Ca content was decreased ( P <  0.05) linearly as dietary NPP level increased and Ca: NPP ratio decreased. Our results indicated that dietary high NPP level along with low Ca: NPP ratio can reduce growth performance and disrupt Ca and P metabolism together with the changes of serum characteristics in goslings at the starter period. [ABSTRACT FROM AUTHOR]

The high-throughput technique of diffusion multiples has been utilized to unveil the effect of solutes on the mechanical properties (yield strength, elastic modulus, hardness), as well as on slip activity, in β (bcc) quaternary Ti alloys. Using this methodology, libraries of [134] Ti-Al-Cr-Mo and [113] Ti-Al-V-Mo single crystals with gradient compositions were generated over distances spanning a few hundred microns and their mechanical properties were probed at room temperature by compression of micropillars milled at selected compositions. Our results evidence that Cr is a more potent strengthener than Mo in Ti-Al-Cr-Mo alloys, and that Mo is very effective in strengthening Ti-Al-V-Mo alloys. Slip activity was measured by observation of slip traces. In all single crystals investigated, irrespective of orientation and composition, plastic strain was accommodated by cross slip between different {110} planes. The specific combination of {110} slip systems that act cooperatively to accommodate strain, as well as the amount of strain accommodated by each slip system, however, is dependent on orientation and on composition. Anomalous {110} slip was observed in the Ti-Al-V-Mo alloys. The incidence of this mechanism was found to increase with increasing Mo. This study highlights the efficiency of diffusion multiples for non-trivial materials' discovery and design. [ABSTRACT FROM AUTHOR]

The filling of a membrane tube with self-weight by a fluid is studied theoretically for the first time. The fundamental problem depends on two non-dimensional parameters, β and γ which represent the importance of internal pressure and membrane self-weight respectively. The nonlinear equations are solved by an efficient numerical integration method. It is found that membrane self-weight has considerable effect on the tube geometry and the tension of the membrane at low filling pressures. [ABSTRACT FROM AUTHOR]

This paper aims to identify a well-defined effective diameter of Nanowires (NWs) in evaluating their Young's modulus and to investigate the physical mechanisms behind the achieved surface elasticity. To this end, GaN NWs were considered for which a layer-wise model was developed and the tensile tests were performed based on molecular statics simulations (MSS). It was shown that two previously defined effective diameters result in opposing effects of the surface elasticity and reversed size-dependence of the overall Young's modulus. Subsequently, a proper effective diameter was decided for the NWs, which enables one to correctly interpret atomistic simulations in terms of continuum mechanics concepts. In particular, clear evidence was attained showing that the bond loss on the NW surface results in around 43% surface softening relative to the NW interior and bulk material. [ABSTRACT FROM AUTHOR]

This work aims to investigate the influence of solute segregation at particle-matrix interfaces on the twin activity of aged Mg alloys. With that purpose a binary Mg-8Al alloy (wt%) and two ternary Mg-8Al-1 Zn and Mg-8Al-1Ag alloys (wt%) were first homogenized and then aged in order to obtain comparable precipitate distributions. Particle-matrix interfaces in the binary alloy were observed to be clean, while Zn and Ag atomic segregation was clearly present at the interfaces of the ternary alloys. Room temperature micropillar compression tests were carried out in grains with favorable orientations for tensile twinning in the homogenized and the aged conditions for the three materials under investigation. The activation of twinning and slip was then characterized by electron microscopy. This study shows that while in the binary alloy precipitation did not lead to any major changes in the twinning activity and, in particular, it did not prevent the formation of thick twin lamellae encompassing the entire width of the tested micropillars, a drastic reduction of the twin activity took place in the aged ternary alloys. In the latter, straining led to the formation of narrow twin lamellae belonging to a single variant, and occasionally arrested at the interior of the micropillars. We propose that the drastic reduction of the twin volume fraction in the aged ternary alloys may be attributed to the decrease of the particle-matrix interface energy due to Zn and Ag segregation, which would hinder re-nucleation at such interfaces, thus suppressing twin propagation. [Display omitted] [ABSTRACT FROM AUTHOR]

Blade fatigue is a widely concerning issue when a turbine transforms ocean energy into electronic power. The frequent changes in flow velocity may cause a wide range of hydraulic excitation frequencies and result in blade resonance. The hydrodynamic damping ratio is of great importance in assessing the resonance amplitude in the design stage. However, it is difficult to make accurate predictions through the basic prediction equation (BPE) because some key flow parameters are not fully taken into account. The present research simplifies the blades as hydrofoils and devotes to improving the accuracy of the BPE. Firstly, multiple correction terms (including velocity, attack angle, and tip clearance correction terms) relative to the BPE are proposed, based on previously published works. Secondly, a comprehensive empirical equation (CEE) is constructed, by coupling the BPE and multiple correction terms. Accuracies of the CEE for first bending and torsional modes are evaluated separately In particular, the average error of the CEE for the first bending mode decreases from 57.16% to 9.87% in comparison with that of BPE. And the average error decreases from 259.48% to 50.72% for the first torsional mode. CEE provides a new tool for engineering evaluation of the resonance failure of blade-like structures. • The hydrodynamic damping behavior in the lock-in region is captured with a Gaussian function. • A CEE is constructed by considering the multiple influencing parameters of the hydrodynamic damping ratio. • The average prediction accuracy of the CEE improves from 57.16% to 9.87% compared to that of the basic prediction equation. [ABSTRACT FROM AUTHOR]

Transformation of the tube-side mass transfer coefficient derived in hollow fibre membrane contactors (HFMC) of different characteristic length scales (equivalent diameter and fibre length) has been studied when operated in the low Graetz range ( Gz <10). Within the low Gz range, mass transfer is generally described by the Graetz problem ( Sh =3.67) which assumes that the concentration profile comprises a constant shape over the fibre radius. In this study, it is experimentally evidenced that this assumption over predicts mass transfer within the low Graetz range. Furthermore, within the low Gz range (below 2), a proportional relationship between the experimentally determined mass transfer coefficient ( K ov ) and the Graetz number has been identified. For Gz numbers below 2, the experimental Sh number approached unity, which suggests that mass transfer is strongly dependent upon diffusion. However, within this diffusion controlled region of mass transfer, tube-side fluid velocity remained important. For Gz numbers above 2, Sh could be satisfactorily described by extension to the Lévêque solution, which can be ascribed to the constrained growth of the concentration boundary layer adjacent to the fibre wall. Importantly this study demonstrates that whilst mass transfer in the low Graetz range does not explicitly conform to either the Graetz problem or classical Lévêque solution, it is possible to transform the experimentally derived overall mass transfer coefficient ( K ov ) between characteristic length scales ( d h and L ). T h is was corroborated by comparison of the empirical relationship determined in this study ( Sh =0.36 Gz ) with previously published studies operated in the low Gz range. This analysis provides important insight for process design when slow tube-side flows, or low Schmidt numbers (coincident with gases) constrain operation of hollow fibre membrane contactors to the low Gz range. [ABSTRACT FROM AUTHOR]

The medium-Mn steel with M 3 characteristics (multi-phase, multi-scale, meta-stable) is a promising third-generation automotive steel. Its chemical composition, microstructure, thermal and mechanical properties are introduced and a warm stamping process for the medium-Mn steel is proposed. The optimal process parameters are identified through mechanical testing and microscopic analysis to achieve balanced properties of hardenability, hardness, strength, elongation and fracture behavior. The optimal forming process consists of an austenitization temperature of 790–840 °C, a soaking time of 4–7 min, an initial stamping temperature of 450–500 °C, and a cooling rate of 10–60 °C/s. A typical automotive structural part B-pillar was stamped using the proposed process and the final part exhibits ultrafine martensite-lath microstructure and desired mechanical properties for intrusion prevention and energy absorption. [ABSTRACT FROM AUTHOR]

The influence of massive laser shock peening (LSP) impacts with coverage area on tensile properties of AM50 magnesium alloy was investigated using MTS880-10 servo-hydraulic material testing machine system. Microstructure in the surface layer and fracture morphologies of as-machined and LSPed tensile specimens were also characterized and analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and cross-sectional optical microscopy (OM). Special attention is paid to the crack initiation location as a function of LSPed coverage area in the gauge part of tensile specimen. Experimental results and analysis indicate that coverage area significantly influenced tensile properties of the tensile specimen. In addition, the grain refinement process in the top surface layer of AM50 magnesium alloy caused by massive LSP impacts is presented. Furthermore, the underlying influence mechanism of LSPed coverage area on tensile properties and crack initiation location of tensile specimen was clearly revealed. [ABSTRACT FROM AUTHOR]

The classic problem of a circular tube or ring buckled by external pressure is investigated by including geometric nonlinearity, material nonlinearity and initial residual stress. Perturbation theory for buckling and immediate postbuckling agree well with numerical integration. It is found that for softening materials the postbuckling may be unstable and catastrophic snap through may occur. [ABSTRACT FROM AUTHOR]

This paper is devoted to discuss arbitrarily switching control problem for a class of nonlinearly parameterised nonlinear switched systems. Compared with the existing results, improvements are that a systematic procedure is given for an explicit construction of a common smooth adaptive controller independent of the switching signals. Meanwhile, the developed design method can be extended to the adaptive arbitrarily switching stabilisation problem for a class of cascade switched nonlinear systems. The theoretical analysis is presented for the Lyapunov stability of the resulting closed-loop switched system and the convergence of the original switched system states at the equilibrium under arbitrary switching. Moreover, the effectiveness and feasibility of the developed method are demonstrated by both a numerical example and a chemical system. [ABSTRACT FROM AUTHOR]

In this paper, the 4LiBH 4 –LiAlH 4 –MgF 2 ternary reactive system was constructed to investigate its de-/rehydrogenation properties and reaction mechanisms. It was found that the 4LiBH 4 –LiAlH 4 –MgF 2 system starts to release hydrogen at about 100 °C and totally desorbs about 8.9 wt.% of hydrogen up to 480 °C. These dehydrogenation properties are much better than those of the 2LiBH 4 –LiAlH 4 , 2LiBH 4 –MgF 2 and 4LiBH 4 –LiAlH 4 –MgH 2 systems. Thermal dehydrogenation of the 4LiBH 4 –LiAlH 4 –MgF 2 system proceeds mainly in three steps with MgAlB 4 , LiH and LiF as the desorbed products. After rehydrogenation at 400 °C under 6 MPa hydrogen pressure, about 4.9 wt.% of hydrogen can be desorbed during the second dehydrogenation process. [ABSTRACT FROM AUTHOR]

In the high-speed machining of hardened steel for the die and mould industry, determining how to reduce the wear of coated carbide tools and improve their machining efficiency and quality has been an important subject. This study investigated the high-speed machining of hardened steel (SKD11/HRC 62, S136/HRC 51) using two types of PVD-coated carbide tools (TiAlN and TiSiN) to determine the mechanism of cutting tool wear and breakage and the effects of tool angle, tool diameter, tool extended length, cutting force and cutting-induced vibration on the tools. The results indicated that the dominant wear patterns of coated carbide tools included flank wear, rack face wear, breakage and micro-chipping. The modes of breakage of the coated carbide tools used for the high-speed milling of hardened steel were coating peeling, chipping and tip breakage. The lives of the cutting tools coated with TiSiN were longer than those of the tools coated with TiAlN due to reduced abrasive wear. The tool extended length during machining caused chips to transform from spiral chips into c-shaped chips and produce sawtooth chips as the length increased. The selection of the optimal tool extended length can deliver the minimum cutting force, a small degree of tool wear and the best machining quality. The characteristics of the cutting force can distinctly reflect abnormal conditions as the cutting tool wears. A tool with a small rake angle, suitable clearance angle and large helix angle will not only reduce the cutting force but also ensure a smooth cutting process and generate less cutting tool wear. [ABSTRACT FROM AUTHOR]

Highlights: [•] Vibrating membranes composed of long strips with local enlargement may lead to trapped modes. [•] Often there exists a much lowered fundamental frequency which dominates the vibration mode. [•] Results are applicable to vibrating plates, acoustic and EM waveguides, and quantum waveguides. [Copyright &y& Elsevier]

Abstract: Vibration of a circular plate internally concentrically supported is basic in structural mechanics. The complete first six frequencies and mode shapes are determined for clamped, simply-supported, sliding, and ring supports using exact characteristic frequency equations. Complex mode switches occur as the support radius is varied. Asymptotic formulas for large support radii are derived. Different types of singularities as the support radius shrinks to zero are distinguished and classified. [Copyright &y& Elsevier]

Highlights: [•] Re and Ru synergistic effects in nickel-based superalloys are investigated. [•] The Al site occupation of Re atom in the γ′ phase is observed directly. [•] The addition of Ru results in the repartitioning of Re to γ phase. [ABSTRACT FROM AUTHOR]

Abstract: A Ritz method for solving slip flow in general ducts is introduced. The method is robust and efficient. It is applied to the slip flow in super-elliptic ducts which are difficult to treat by existing methods. Super-elliptic ducts, resembling rectangular ducts with rounded corners, are extensively used in microfluidics. [Copyright &y& Elsevier]

Abstract: Mg–Al co-doped ZnO thin films were prepared via radio-frequency reactive magnetron sputtering technique. X-ray diffraction investigation showed all the thin films with different Mg:Al ratio had hexagonal wurtzite structure. All the thin films showed (100) preferential orientation of ZnO. When Al concentration was kept constant but Mg concentration was increased, the grain size decreased at first and then increased. When Mg:Al ratio was 3:1, the grain size reached a maximum. Ultraviolet–visible spectra showed the thin films had a high average transmittance of 80% in the visible range. The optical band gaps of the thin films were obtained as follows: 3.31, 3.32, and 3.37eV, corresponding to the Mg:Al ratio of 0:1, 1:1, and 3:1, respectively. Photoluminescence spectroscopy showed all the thin films had four main peaks located at 386, 410, 463, and 499nm. The origin of blue peak is oxygen vacancy. When Mg concentration was kept constant but Al concentration was increased, I–V curve presented that for both of the heterojunctions the rectifying behavior was formed. The conductivity of Mg:Al=1:1 thin film is higher than that of Mg:Al=1:0 thin film. After illumination, light I–V curve deviated from rectifying character. [Copyright &y& Elsevier]

The aim of this 2008-2012 study was to prove the hypothesis that the Three Gorges Reservoir ( TGR) and the upper free-flowing section can offer a habitat for restocking the Chinese sturgeon, Acipenser sinensis. Thus, 498 cultured A. sinensis (including 28 sub-adults tagged with ultrasonic transmitters) were released into the TGR and the adjacent free-flowing section of the Yangtze River. The distribution, movement and growth of the released fish were collected by acoustic telemetry and bycatch information. Results indicated that only three sub-adults migrated upstream to the free-flowing section where they remained for the three-year observation (limited by the longevity of the transmitter battery). However, most sub-adults migrated downstream after release, with a migration distance of 15-877 km as well as a tracking duration from 19 to 6063 h. The downstream traveling speed in the free-flowing section (mean = 3.70 km h−1, range = 1.51 -8.25 km h−1) was significantly faster than that in the reservoir section (mean = 1.05 km h−1, range = 0.12 -1.82 km h−1; p < 0.05). Only three sub-adults migrated to within 3 km of Three Gorges Dam ( TGD) and stayed in the reservoir. Sub-adults stayed obviously deeper within the reservoir (mean = 11.47 m) than in the free-flowing section (mean = 3.63 m; p < 0.05). Juveniles were recaptured from 45 -810 km downstream their release sites with a mean traveling speed of 1.05 km h−1 (range = 0.13 -1.82 km h−1), lower than that of the sub-adults released in the free-flowing section. Twelve percent of juveniles released in one of the tributaries of the Yangtze River found the entrance and migrated downstream to the reservoir within the first 30 days. Average body weight of the recaptured juveniles increased by 10.3% (range = 2.3% -15.3%) and some crustaceans (e.g. river shrimp) were found in the stomach and gut of two juveniles. The results demonstrate that the TGR and its adjacent upstream free-flowing Yangtze River section can serve as reintroduction sites to support a certain quantity of Chinese sturgeon to remain and mature there. [ABSTRACT FROM AUTHOR]

Highlights: [•] Porous Ti with various pore size and porosity was made using PMMA as space holder. [•] Compressive strength and modulus vary with the porosity and macro-pore size. [•] The failure of the struts on porous Ti is controlled primarily by macro-pores. [•] Compressive fractography shows the brittle cleavage fracture mainly. [ABSTRACT FROM AUTHOR]

The aim of this work is to investigate the interaction of basal dislocations and twin boundaries with ultrafine basal disk-shaped precipitates at the atomic scale in the peak-aged Mg-1Mn-1Nd-3Zn (wt.%) alloy. With that goal, an experimental approach consisting on micropillar compression of two grains oriented favorably for basal slip and for tensile twin activation, respectively, as well as high resolution transmission electron microscopy, was put in place. First, a novel mechanism of interaction between particles and basal dislocations was observed. In particular, the movement of dislocations along basal planes led to the dissolution of the ultrathin basal precipitates in the nearby regions (within 80 nm) and to solute diffusion resulting in microsegregation of solutes at the slip lines. Hindering of basal slip due to such microsegregation prevented slip localization by promoting the consecutive activation of softer basal planes. Second, twin-precipitate interactions were found to be dependent on the twin boundary plane. In particular, bypassing of precipitates by coherent twin boundary segments were observed to lead to elastic rotations of the precipitate lattice, while the interaction of CTB/prismatic-basal intersections with precipitates resulted in precipitate shearing along prismatic planes. [Display omitted] [ABSTRACT FROM AUTHOR]

Highlights: [•] We explore the spin transport properties of the chemically functionalized graphene nanoribbon. [•] The calculated I–V curves exhibit negative differential resistance. [•] Chemically functionalized graphene nanoribbon can be used as molecular spin electronic device. [Copyright &y& Elsevier]

Slip flow occurs in a wide variety of practical chemical engineering processes. This work models, for the first time, the interaction of surface slip and system rotation normal to the flow direction. It is found that the flow fields are affected considerably. For Poiseuille flow, slip increases the longitudinal flow rate at low rotation, but decreases it at high rotation. For Couette flow, slip decreases the longitudinal drag. The solutions are also exact solutions of the Navier-Stokes equations. [ABSTRACT FROM PUBLISHER]

We consider in this article a problem of finding paths in a graph within a distance window, termed distance-confined path problem and develop a successive graph reduction scheme to solve such a problem effectively. Integrated with the surrogate constraint formulation, our proposed solution algorithm for the distance-confined path problem finds a prominent application in separable non-linear integer programming. By forming a family of distance-confined path problems, we are able to remove gradually all primal infeasible points in the region defined by the surrogate constraint and eventually achieve an exact equivalence between the surrogate constraint formulation and the primal problem, thus a zero duality gap. [ABSTRACT FROM AUTHOR]

Abstract: An axisymmetric stagnation flow impinges on a moving plate with different slip coefficients in two orthogonal directions. Such anisotropic slip occurs on geometrically striated surfaces and superhydrophobic strips. A similarity transformation reduces the Navier–Stokes equations to a set of 10th order nonlinear ordinary differential equations. The problem is solved by asymptotic analysis for large slip and numerical integration. Anisotropy is reflected in the differences of slip velocities in the two directions, and may be considerable. [Copyright &y& Elsevier]

The endoparasitic nematophagous fungus,Esteya vermicola, has potential as a biocontrol agent against pinewood nematode,Bursaphelenchus xylophilus. AnE. vermicolaconidial formulation was developed to improve conidial resistance to ultraviolet (UV), drought and heat stress. The effective concentration of each protective additive [UV protectant [fulvic acid (FA) and skim milk (SM)]; drought protectant (sorbitol) and heat protectant (calcium chloride)] was determined based on the germination rate ofE. vermicolaconidia after exposure to the different stressors. A combination of 0.2% FA and 4% SM, 5% sorbitol and 0.05% calcium chloride provided the most effective protection. In addition, the concentrations of spreader–sticker and antibiotic were also decided. The final formulation could be used to improve the resistance ofE. vermicolaconidia to multiple stressors and to increase nematode mortality compared with unformulated conidia. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, micro-drills with diameters of 0.1–0.3mm were used to drill printed circuit boards (PCBs) with a highest spindle speed of 300krpm. To study the wear mechanisms of PCB micro-drills, micro-drill morphology was observed, and the flank wear of the micro-drills was measured. The factors affecting flank wear were studied. In addition, hole wall roughness, nail head formation, and the accuracy of hole location were measured and analysed to determine how micro-drill wear influenced hole quality. It was found that abrasion was the main mechanism controlling the deterioration of cemented tungsten carbide micro-drills. The aggressive rubbing by glass fibre broken chips and reinforcing fillers, and the diffusion of cobalt caused abrasive wear of the flank, the chisel edge, the rake face, and the minor flank of the micro-drills. Resin that was softened by cutting heat would adhere to the micro-drills, which decreased chip removal and the accuracy of hole location. Micro-drill wear was inclined to cause nail heads and decrease the accuracy of hole location. [Copyright &y& Elsevier]

Abstract: The present study describes a direct shoot regeneration-based micropropagation procedure for the self-heading cultivars of Philodendron. Three types of explant (i.e. leaf lamina, petiole, stem nodal segment) were screened for their shoot induction potential following a three months treatment with 0.5mgl−1 of either 2,4-dichlorophenoxyacetic acid (2,4-D), thidiazuron (TDZ) or both. Results indicated that the leaf laminas were poor candidates for shoot induction whereas the petioles showed potential for adventitious shoot production at frequencies of 2.8–11.1% in two of the cultivars tested. Stem nodal segments were the most responsive among the three as shoots formed directly following the TDZ treatment at frequencies of 16.7–41.7% depending on the cultivar. When comparing the effectiveness of different cytokinins to induce shoot proliferation on stem nodal segments, it was found that the 0.5 and 1mgl−1 of kinetin (Kn) and 6-benzyladenine (BA) treatments resulted in higher shoot formation percentages compared to the 0.5 and 1mgl−1 of TDZ treatments in two of the three cultivars. Furthermore, more shoots were produced on BA than on Kn-supplemented media in all the three cultivars. Shoots derived from the 0.5mgl−1 of BA treatment can be induced to root following one month incubation with 0.1–1mgl−1 of indole-3-butyric-acid (IBA). The rooted shoots showed 100% survival after acclimatization in the greenhouse. The procedure reported in the present study can assist in the large-scale multiplication of elite self-heading cultivars of Philodendron in the future. [Copyright &y& Elsevier]

Oscillatory channel flow in a rotating system is considered. The Navier-Stokes equations reduce to the Ekman equations that are solved exactly. The results show the interaction between oscillation frequency and rotation rate. Resonance occurs when the oscillation frequency is twice the rotation rate. [ABSTRACT FROM AUTHOR]

Abstract: In this paper the nonlocal shell and beam theories are used to study the transverse vibration of slender NTs. The agreement between the shell model and molecular dynamics simulations shows that the nonlocal effect originates predominantly from the atom-atom interaction in circumferential direction. It thus does not decrease with rising axial wavelength. In this case, a nearly constant nonlocal coefficient e 0 can be achieved for vibrating NTs. These behaviors however cannot be captured by the widely used nonlocal beam theory where only the axial nonlocal effect is included. Thus, caution must be taken when the one-dimensional nonlocal model is applied to slender NTs. [Copyright &y& Elsevier]

Presented herein are exact solutions for the free vibration problems of a class of annular plates with parabolically varying rigidity and for a sandwiched non-uniform annular plate. These exact solutions are useful for verifying numerical methods and algorithms. [ABSTRACT FROM AUTHOR]

Abstract: The effect of the axisymmetric spreading of a layer of material (oil or solid particles) on the surface of a viscous fluid is studied. Assuming high Reynolds numbers, the boundary layer equation is derived and solved for general power law surface velocities. The composite streamlines show sharp turns near the surface. [Copyright &y& Elsevier]

Abstract: The slip flow due to a stretching cylinder is studied. A similarity transform reduces the Navier–Stokes equations to a set of non-linear ordinary differential equations. Asymptotic solutions for large Reynolds number and small slip show the problem can be related to the existing two-dimensional stretching cases. Due to algebraic decay, the equations are further transformed through a compressed variable, and then integrated numerically. It is found that slip greatly reduces the magnitudes of the velocities and the shear stress. [Copyright &y& Elsevier]

Abstract: Similarity solutions are essential for understanding nonlinear viscous fluid flow. The similarity transform reduces the Navier–Stokes equations to a set of nonlinear ordinary differential equations, which can be solved to yield universal curves. This paper reviews the advances in similarity solutions of a viscous fluid due to a stretching boundary. [Copyright &y& Elsevier]

We show that a unique, nontrivial, natural convection state exists under the Boussinesq approximation and completely passive boundary conditions. The authors show that a unique, nontrivial, natural convection state exists under the oussinesq approximation and completely passive boundary conditions [ABSTRACT FROM AUTHOR]

Abstract: ZnO–CNT nanotubes (NTs) have been fabricated by coating carbon nanotubes with zinc oxide (ZnO). One of their potential applications is the pressure/stress sensors based on their vibration sensitivity to external pressure. To implement the application, this paper aims to develop a mechanics model to quantify the pressure dependence of the NT vibration, identify the major factors that determine the pressure sensitivity and investigate the physics of the pressure-dependent vibration. The linear pressure dependence of the NT frequency is achieved with the pressure derivative rising rapidly with the radius of the core CNTs. The results provide essential information for the development and optimum design of the nanosensors, and offer useful guidance for further research on the mechanics of the hybrid nanostructures. [Copyright &y& Elsevier]