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Hypothesis Droplet spreading on surfaces is a ubiquitous phenomenon in nature and is relevant with a wide range of applications. In practical scenarios, surfaces are usually associated with certain levels of vibration. Although vertical or horizontal modes of vibration have been used to promote droplet dewetting, bouncing from immiscible medium, directional transport, etc., a quantitative understanding of how external vibration mediates the droplet behaviors remains to be revealed. Methods We studied droplets impacting on stationary and vibratory surfaces, respectively. In analogy to the Weber number We = ρ U i 2 D 0 / γ , we define the vibration Weber number We * = ρ U v 2 D 0 / γ to quantitively analyze the vibration-induced dynamic pressure on droplet behaviors on vibratory surfaces, where ρ , γ , D 0 , U i and U v are liquid density, surface tension, initial droplet diameter, impact velocity of the droplet, and velocity amplitude of vibration, respectively. Findings We demonstrate that the effect of vibration on promoting droplet spreading can be captured by a new scaling number expressed as We * / [ We 1\2 sin ( θ/2 ) ] , leading to (Dm − Dm0)/Dm0 ∝ We * / [ We 1\2 sin ( θ/2 ) ] , where θ is the contact angle, and Dm0 and Dm are the maximum diameter of the droplet on stationary and vibratory surfaces, respectively. The scaling number illustrates the relative importance of vibration-induced dynamic pressure compared to inertial force and surface tension. Together with other well-established non-dimensional numbers, this scaling number provides a new dimension and framework for understanding and controlling droplet dynamics. Our findings can also find applications such as improving the power generation efficiency, intensifying the deposition of paint, and enhancing the heat transfer of droplets.

The microstructure evolution and its effect on the impact toughness of a new Ni-Fe based alloy GH984G, used in 700 °C ultra-super critical coal-fired power plant, were investigated during thermal exposure at 650 °C–750 °C for up to 10,000 h. The results show that the impact toughness at room temperature drops rapidly at the early stage during thermal exposure at 700 °C and then has no significant change even if after exposure for 10,000 h. The significant decline of the impact toughness is attributed to the coarsening of M23C6 carbides at grain boundaries, which weakens the grain boundary strength and leads to the aging-induced grain boundary embrittlement. The M23C6 carbides have almost no change with further thermal exposure and the impact toughness also remains stable. Additionally, the impact toughness rises with the increase of thermal exposure temperature. The size of γ′ after thermal exposure at 750 °C for 10,000 h is much bigger than that at 650 °C and 700 °C for 10,000 h. Therefore, the intragranular strength decreases significantly due to the transformation of the interaction between γ′ and dislocation from strongly coupled dislocation shearing to Orowan bowing. More plastic deformation occurs within grains after thermal exposure at 750 °C for 10,000 h, which increases the impact toughness.

This study investigates how uncertainty (economic policy uncertainty, market-based uncertainty, firm-specific uncertainty, and CAPM-based uncertainty) impacts the Chinese listed firms’ capital structure for the period 1999–2016, and further tests whether this relationship varies for state-owned enterprises (SOEs) and non-SOEs. In addition, we examine the moderating effect of a non-formal financing channel (trade credit) on the relationship between leverage and uncertainty. The findings show that firms decrease the level of leverage with an increase in uncertainty, and this impact is less prominent for firms owned by the state. Furthermore, the results reveal that trade credit decreases the negative association between uncertainty and leverage, suggesting that firms (especially non-SOEs) adjust their financing demands by using trade credit under high uncertainty. The findings provide implications for corporations and policymakers about how capital structure decisions are influenced by different types of uncertainties in a firm’s environment.

This study investigates the effects of firm-specific, market-based, CAPM-based, and economic policy uncertainty on the relationship between leverage and investment for firms of different nature, i.e., state-owned enterprises (SOEs) and non-state-owned enterprises (non-SOEs). The study uses a panel of Chinese listed firms covering the period 1999–2016 and applies a robust two-step system Generalized Method of Moments technique to cope with the endogeneity problem. The findings show that leverage has a significant and adverse impact on non-SOEs investment behavior. The results further show that firm-specific and market uncertainties exacerbate the negative effect of leverage on investment for non-SOEs. However, economic policy uncertainty and CAPM-based uncertainty attenuate the association between leverage and investment for SOEs and non-SOEs, respectively. Overall the results suggest that the impact of leverage on investment can be mitigating or exacerbating depending on the underlying uncertainty and the nature of the enterprise.

The effect of initial alloy state on hot deformation and dynamic recrystallization (DRX) of GH984G alloy, used to manufacture large scale forgings for 700 °C advanced ultra-supercritical (A-USC) coal-fired power plants, was studied by isothermal compression test. The experimental results show that the apparent activation energy of hot deformation for the as-cast alloy is larger than that of the hot-rolled alloy. The reasonable ranges of processing parameters for the as-cast and hot-rolled alloys are 1100–1200 °C/0.01–0.5 s−1 and 1100–1200 °C/1.0–10 s−1, respectively, based on the processing maps. The flow instability domain of the as-cast alloy is larger than that of the hot-rolled alloy. The different hot deformation behaviors of the as-cast and hot-rolled alloys result from the various initial grain sizes and DRX mechanisms. The main DRX nucleation mode of the as-cast alloy with large grains is continuous dynamic recrystallization (CDRX). However, for the hot-rolled alloy with fine grains, the discontinuous dynamic recrystallization (DDRX) is dominant.

A key issue in practical option pricing with stochastic volatility models is the choice of feasible model parameters, which can be realized by calibration. Aiming to improve the reliability of calibration results for out-of-sample option pricing without changing original model setting, we introduce a Bayesian approach for calibration with time-based rescaling of option data, which is realized by assuming pricing errors with time-varying variances in the state-space model. The calibration procedure is implemented with Markov chain Monte Carlo (MCMC) algorithm. Empirical tests in SPX option market show strong preference for models calibrated with our method in out-of-sample option pricing, compared with models calibrated without any rescaling of data.

The tensile properties and deformation behavior of several cast Ni-based superalloys, respectively, in the equiaxed, columnar-crystal and single-crystal styles are comparatively studied. The effects of solidification way, heat treatment and strain rate on the tensile properties are discussed in detail. It is found that the reduction of grain boundaries by the feasible solidification ways offers cast Ni-based superalloys the potential capability of improving the mechanical properties, the ultimate achievement of which is also confirmed to lie on the appropriate modifications of chemical composition and heat treatment. The prolongation of solid solution facilitates the precipitation of fine secondary γ′ phase, whereas the extension of high-temperature aging leads to the coarsening of secondary γ′ phase. The combination of these two aspects has a crucial influence on the tensile properties. Under tensile applied stress, the surface grains of DZ-A alloy deform slightly, while the inner grains deform heavily. This deformation inhomogeneity is ascribed to the occurrence of cracks or oblique grains near the surface of specimens and the sliding or decohesion of grain boundaries between the surface and inner grains. Regardless of strain rate, the ILTDM (intermediate-low-temperature ductility minimum) phenomenon always happens in the temperature range from 400 to 600 °C in all the investigated alloys, the occurrence of which is closely related to the strong strain-hardening behavior in the deformation process. Finally, the interaction of slip bands which are the main deformation mode below 600 °C is established to be the essential reason for the strain hardening.

In recent years, the question of how uncertainty influences corporate decisions has received greater interest among academics, researchers, and corporations. This study is an attempt to investigate how uncertainties (firm-specific uncertainty (fsu), market-based uncertainty (mu), and economic policy uncertainty (epu)) influence research and development (R&D) investment and to further examine whether this relation is moderated by product market competition across firms of different sizes. Using a sample of Chinese listed firms covering 2000–2017, this study applies a two-step system GMM model to perform estimations and control for endogeneity issues. The findings show that uncertainties (fsu, mu, and epu) negatively influence R&D investment and that this negative relationship is more prominent for firms operating in competitive industries. In concentrated industries, however, the negative impact of uncertainty is mitigated for large firms, which have more internal resources and better access to external financing. This study contributes to real options theory by illustrating how different forms of uncertainty embedded in a firm’s internal and external environment reduce R&D investment, and by indicating how this relationship is moderated by product market competition.

Savings and Credit Co-operative Societies (SACCOS) increasingly recognized as the valuable tool for economic development in low-income countries. However, recently researchers reported that one of their primary challenges to their expansion is the high level of inefficient. In this study, we analyzed the relationship between growth and efficiency of SACCOS using economies of scale concept. Then we address the role of management of the capital structure and allocation of resources in the expansion of SACCOS. The study used financial statement data from 60 SACCOS in Tanzania for the period of 2004–2011. The findings supports that most of SACCOS are small and cost inefficient because the industry is young, but, the efficiency increases as SACCOS expand. Second the allocation of resources in liquid, financial and non-financial investment leads to no expansion in SACCOS. Thus, the growth of SACCOS via increasing loan to members, members’ savings, shares, and institutional capital should be encouraged as it increases the efficiency of SACCOS. Also, SACCOS should minimize the allocation of assets in other investments which are different from credit to members.

Investigations into the thermal stability of primary MC carbide (TSMC) during long-term thermal exposure and its effects on the performance of nine cast Ni-based superalloys with different Nb/Ti and (W + Mo)/Cr ratios have been undertaken. The results show that the chemical composition of primary MC can be precisely modified by the Nb/Ti ratio of alloys while the distribution and morphology of primary MC carbides is not affected. During long-term thermal exposure, the TSMC is dependent not only on the composition of primary MC, i.e. the Nb/Ti and (Nb + Ti)/(W + Mo) ratios of primary MC, but also on the (W + Mo)/Cr ratios of the alloys, and the latter has a more significant effect than the formers. With the decrease of these parameters, the TSMC decreases and more degeneration reactions of primary MC occur during thermal exposure. Moreover, with the (W + Mo)/Cr ratio of the alloys decreasing from 0.55 to 0.37 and finally to 0.22, the transformed carbides from primary MC change from M6C to coexist of M6C and M23C6 and to M23C6. With the decrease of TSMC, the stress-rupture life of alloy at 800 °C/294 MPa is improved, because that more secondary carbides precipitate in the matrix which can retard or even suppress the topologically close-packed (TCP) phases.

A new low cost hot-corrosion resistant Ni–Fe–Cr based superalloy is designed and fabricated. The microstructure evolution, mechanical properties and effect of minor Cr variation on the microstructure stability during long-term thermal exposure have been investigated in details. Microstructure observations reveal that the new Ni–Fe–Cr based superalloy is constituted of γ matrix, γ′ precipitate, primary MC carbide and grain boundary (GB) M23C6 carbide after standard heat treatment. During long-term thermal exposure at 850 °C, the γ′ precipitate coarsens greatly within 3000 h, which significantly degrades the room temperature hardness and stress-rupture life at 800 °C/294 MPa. The primary MC degenerates gradually by reactions of MC + γ → M23C6 + γ′, MC + γ → M23C6 + M6C + γ′ and MC + γ → M23C6 + M6C + η, respectively. The growth of carbide and γ′ along GB changes it from thin discontinuous chain structure to coarse continuous chain structure, which might lead to the intergranular fracture during stress-rupture. In addition, small amount of grain interior (GI) M23C6 carbide precipitates in the matrix, which has negligible influence on the stress-rupture property. Moreover, minor increase of Cr content (from 20% to 21%) extends the precipitating temperature range of σ phase and enhances its precipitating peak temperature, which results in a large amount of σ phase precipitates in the Ni–Fe–Cr based superalloy during long-term thermal exposure at 850 °C. The formation of σ phase increases the room temperature hardness but degrades the stress-rupture life and elongation of the Ni–Fe–Cr based superalloy greatly.

The developing economies are experiencing a growing trend of financial Linkage between formal and less-formal financial institutions. Normally, less-formal financial institutions receive loanable funds from formal financial institutions as an approach to meet their financing deficit, while formal financial institutions engage in linkage as a mean to expand business. The main concern of stakeholders regarding this practice is how such linkage can affect the performance of the less-formal financial institutions. In Tanzania, the Savings and Credit Co-operative Societies (SACCOS) are the most used less-formal financial institutions which are also highly involved in financial linkage. In this study therefore, we used Tanzania SACCOS’ financial statement data, for the period of 2004–2011, and panel data regression model to examine the relationship between financial linkage (measured as financial dependency ratio) and sustainability (measured as Operational Self Sufficiency) of less-formal financial institutions. The findings suggest that the higher the level of financial linkage the more the SACCOS become unsustainable. Implying that, to be sustainable institutions, the SACCOS should try keep away from the use of external funds in their loan portfolio.

GH984G alloy is a low cost Ni–Fe based wrought superalloy designed for 700 °C advanced ultra-supercritical (A-USC) coal-fired power plants. In this paper, the microstructure evolution and tensile properties of GH984G alloy with different Ti/Al ratios during thermal exposure at different high temperatures are investigated. Detailed microstructure analysis reveals that the Microstructure of alloys with different Ti/Al ratios are similar after standard heat treatment, and the primary precipitates are γ′, MC, M 23 C 6 and M 2 B. However, η phase precipitates at grain boundary in the alloy with high Ti/Al ratio after thermal exposure at 750 °C for 570 h. By contrast, the microstructure stability of the alloy with lower Ti/Al ratio is excellent. There is no detrimental phase even if after thermal exposure at 750 °C for 5000 h in the alloy with lower Ti/Al ratio. γ′ coarsening plays a great role on the tensile strength, and the critical size range of γ′ could be defined as approximately 27–40 nm. The influence of η phase on tensile strength has close relationship with its volume fraction, the high volume fraction results in the decrease of tensile strength. The tensile strength of the alloy with lower Ti/Al ratio is obviously higher than the alloy with higher Ti/Al ratio and the yield strength has no obvious decrease during long-term thermal exposure at 700 °C. It is demonstrated that the thermal stability of microstructure and mechanical properties of GH984G alloy can be improved by moderately decreasing Ti/Al ratio to satisfy the requirement of A-USC plants.

The influence of phosphorus on hot deformation microstructure of GH984G alloy was investigated. The results indicate that phosphorus accelerates the process of dynamic recrystallization (DRX) nucleation and prolongs the time of DRX grain growth. The alloy containing more phosphorus shows greater flow stress and dislocation density in the early stage of hot deformation, while the stress and dislocation density decrease with the increase of phosphorus after further deformation. Phosphorus inhibits the formation of Σ3 twin boundary at low strain rate or high deformation temperature but promotes it at high strain rate and low deformation temperature. The microstructure characterizations reveal that more blocky MC carbides with larger size form in the alloy with higher phosphorus content and serve as strong obstacles to the dislocation movement, thus increasing the flow stress and dislocation density in the early stage of hot deformation. The higher dislocation density promotes the nucleation of dynamic recrystallization and then reduces the flow stress and dislocation density at higher strain. The formation of Σ3 boundaries depends on growth accident during the process of DRX grain growth. More MC carbides in phosphorus-containing alloy decrease the rate of grain boundary migration and the frequency of growth accident, then reduce the fraction of Σ3 boundary. The change of twin boundary with phosphorus content at high strain rate and low deformation temperature is related to the critical grain size of twin formation.

If financial systemic crisis occurred, one of the effective countermeasures is to issue contingent securities like contingent convertible bonds (CoCos). In this paper, we present a new kind of CoCos which is of investor-friendly dual-trigger property, and it is called “Contingent Convertible bond after Converted” which can be put back at a discount price or converted into CoCos prior to an imminent financial systemic risk. We provided the design rule of this bond and a closed-form pricing formula under some assumptions, and this kind of bond is likely to be more powerful in loss absorbing capacity. Consequently, it is necessary to restrain investors’ option to put the CoCoCo back in order to keep loss absorbing capacity more powerful, meaning to limit the discount ratio \( \alpha \) less than 1.

A model is proposed to estimate the probability distribution of asset value based on the benefit effects as well as the risk effects of deposit insurance with the minimum cross-entropy principle. Three scenarios are constructed to depict situations with different dual effects of deposit insurance. The corresponding assets distribution functions are obtained accordingly. The results show that it is positively correlated between the supervision level and the risk aversion effects of deposit insurance. The increase of the deposit insurance premium moves the bank’s assets distribution to the right side although not significantly. The asset probability distributions estimated in this paper can be taken as a reference for banks to choose the proper credit investment projects.

In this paper we examine the role of Savings and Credits Cooperative Societies (SACCoS) in the economic growth of Tanzania by answering two main questions. First, are financial services in SACCoS significant factors for economic growth? Second, are financial services in SACCoS Granger causing economic growth? We use credits-real GDP per capita ratio and savings-real GDP per capita ratio as proxy measures for financial services and real GDP per capita for economic growth. We employ Newey-West standard errors regression model and Wald Granger causality tests in analysis. The sample period is 1990-2012. Data are from the Ministry of Agriculture, Food and Cooperatives, World Economic Outlook (WEO) database, International Monetary Fund (IMF). The findings show that, there is a strong positive association between the financial services and the economic growth, also there istwo-ways Granger causality between them. However, we find out that savings are much important in fostering economic growth as compared to credits/loans. These criteria make SACCoS the distinct microfinance institutions in the economic development in Tanzania and therefore should be promoted with more emphasis on the savings objective.

The mechanism of primary MC decomposition and its influence on the rupture behaviors in the hot-corrosion resistant superalloy K444 are investigated by the combination of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results reveal that the blocky primary MC mainly distributes at interdendritic regions and grain boundaries after the standard heat treatment. During long-term thermal exposure, primary MC decomposes gradually, which can be summarized into three stages. Firstly, the primary MC reacts with the gamma matrix and produces the M23C6 particles and gamma' film, which can be described as MC + gamma -> M23C6 + gamma'. In the second stage, the un-decomposed primary MC arrests the Ni element and forms the M6C particles and eta phase, which can be expressed as MC + gamma -> M6C + eta. In the third stage, the remaining primary MC reacts with the diffused Ni element and forms the eta phase with M6C and M23C6 particles inside, which can be described as MC + gamma -> M6C + M23C6 + eta. The reaction of the second and third stages should be ascribed to the high (Ti + Nb + Hf)/Al ratio and segregated W, Mo and Cr element in the decomposed region. In addition, the platelet-like sigma phase is found in the third stage. The primary MC decomposition has different effects on the rupture behaviors between tensile and stress-rupture test. (C) 2012 Elsevier B.V. All rights reserved.

We consider the valuation of CDO tranches with single factor M G - NI G copula model, where the involved distributions are mixtures of Gaussian distribution and NI G distribution. In addition, we consider two cases for stochastic correlation and random factor loadings instead of constant factor loadings. We analyze the unconditional characteristic function of accumulated loss of the reference portfolio, and derive the loss distribution through the fast Fourier transform. Moreover, using the loss distribution and semi-analytic approach, we can get the CDO tranches spreads.

Based on the mixed control strategy (regular control and impulse dividend control strategy), we formulate a proportional reinsurance model with transaction costs. For getting the maximal return function and associated mixed control strategy, using Ito calculus and classical mixed control theory, we derive the quasi-variational inequality solution to this optimal problem. Furthermore, we obtain its closed forms under some assumptions.

SiC short fibers, with an average diameter of 13 μm, length of 300–1,000 μm and chopped from SiC continuous fibers, were surface modified by the semi-solid mechanical stirring method to produce a discrete coating of aluminum particles. Then the starting mixtures, which consist of SiC short composite fibers, aluminum powder less than 50 μm and α-SiC powder of an average diameter of 0.6 μm, were mechanically mixed in ethanol for about 3 h, dried at 80 °C in air, and hot pressed under 30 MPa pressure at 1,650, 1,750 and 1,850 °C with 1 h holding time to prepare SiCf/SiC composites. Volume fraction of SiC short fibers in the starting powder for SiCf/SiC composites was about 25 vol.%. The composites were characterized in terms of bulk density, phase composition, and mechanical properties at room temperature. In addition, the distribution of SiC short fibers in the matrix and the cracking pattern in the composites were examined by optical microscope. Fracture surface of the composites were performed by a scanning electron microscope (SEM). The effect of hot-pressing temperature on bulk density and mechanical properties was investigated. The results indicated that SiC short fibers were uniformly and randomly distributed in the matrix, bending strength and bulk density of the composites increased with increasing sintering temperature. The composite, hot-pressed at 1,850 °C, exhibited the maximum bulk density and bending strength at room temperature, about 3.01 g/cm3 and 366 MPa, respectively. SEM analyses showed that there were a few of fiber pullout on the fracture surface of samples sintered at 1,650 °C and 1,750 °C, which was mainly attributed to lower densities. But few of fiber pullout was observed on the fracture surface of sample sintered at 1,850 °C, the combined effects of high temperature and a long sintering time were considered as a source of too severe fiber degradation because of the large amount of oxygen in the fibers.

The RMB index was calculated with July 21, 2005, as the base period; the weight of both the broad- and narrow-basket RMB indexes was determined separately; and a functional test was performed. The research indicated that the broad-basket RMB index was more stable and can better reflect the trends of the RMB against a basket of currencies both prior to and as well as in financial crisis. The broad-basket RMB index has better stability compared with the USD index and the Shanghai composite (security) index because the broad-basket RMB index fluctuates less.

A discrete coating of aluminum particles on the surface of Al 2 O 3 particles was prepared by the semi-solid mechanical stirring method. Al 2 O 3 particles with an average diameter of 80 μm, preheated to about 300°C, were added to semi-solid pure aluminum to prepare a slurry by the mechanical stirring method. The volume fraction of Al 2 O 3 particles in the slurry was about 20%. As the ceramic particles were uniformly dispersed in the semi-solid aluminum, the temperature of the slurry decreased quickly, but the slurry continued to be stirred until all the slurry was converted into composite powder. The composite powder was then cooled down to room temperature in a steel block cooler in an argon atmosphere. The surface morphology and transverse sections of the composite powder were examined using a scanning electron microscope (SEM), electron probe X-ray microanalyser (EPMA), optical microscope and augur electron spectroscopy (AES). The results indicate that the composite powder was a mixture of Al/Al 2 O 3composite particles and pure aluminum powder in quasi-spherical shapes. A single layer of nano-, submicron- and micron-sized aluminum particles were coated on the surfaces of the Al 2 O 3 particles. The slurry could be converted into the composite powder resulting from faster solidification of liquid aluminum and mechanical stirring.

Composite powder, which is a mixture of Al/Al 2 O 3 composite particles and nanometer, submicron and micron sized aluminum powder, was prepared by semi-solid mechanical stirring method with addition of Al 2 O 3 ceramic particles. The ceramic particles have an average diameter of 80 μm and a volume fraction of 15% in the slurry. The methods used to measure the size distribution of particles greater than 50 μm and less than 50 μm were sieve analysis and photosedimentation, respectively. The surface morphology and transverse sections of the composite powder of different sizes were examined by scanning electron microscope (SEM), optical microscope and auger electron spectroscopy (AES). The results indicate that the composite powder prepared in present work have a wide size distribution ranging from less than 50–900 μm, and the aluminum particles and Al/Al 2 O 3 composite particles are separated and isolated. The particles greater than 200 μm and less than 50 μm are almost pure aluminum powder. The rate of conversion of ingot aluminum into particles less than 1 μm containing nanometer and submicron sizes is 1.777 wt.% in this work. The aluminum powder of different sizes has different shape and surface morphology, quasi-spherical in shape with rough surface for aluminum particles of micron scale, irregular in shape for aluminum particles of submicron scale, and quite close to a globular or an excellent globular in shape for aluminum particles of nanometer size. On the other hand, the surface of ceramic particle was coated by aluminum particles with maximum thickness less than 10 μm containing nanometer and submicron sizes as a single layer. It is suggested that the surface of ceramic particles can provide more nucleation sites for solidification of liquid aluminum and the nucleation of liquid aluminum can take place readily, grow and adhere on the surface of ceramic particles, although it is poorly wetted by the liquid aluminum and the semi-solid slurry can convert into composite powder owing to the addition of ceramic particles and the shear force of mechanical stirring during solidification.