Mesoscopic modelling and simulation of plasticity in fcc and bcc crystals: Dislocation intersections and mobility

The modelling of dislocation dynamics and interactions in bcc and fcc crystals is examined with particular emphasis on simplified local rules that have to be implemented in mesoscale simulations. The rules for the formation and destruction of dislocation junctions and the relevant laws for dislocation mobility are discussed in some detail. In addition, some of the existing connections between atomistic and mesoscopic scales, on the one hand, and between mesoscopic dislocation properties and yield or flow stresses, on the other hand, are reviewed.     

Research on the frontiers of materials science: The impact of nanotechnology on new material development

Materials continue to play a dominant role in our society, as they have through the millennia. The developments in nanotechnology provide a unique opportunity to not only develop new classes of materials but also do so in harmony with a goal of sustainable development. There is, however, a large gap between the promise of nanotechnology and its integration into a new generation of nano-enabled products. The first half of this paper focuses on the promise of nanotechnology by exploring a novel, self-assembly based technique for the production of structural ceramics, which have the potential to dramatically affect a range of products such as power turbines and aircraft engines. In the second half of the paper examines some of the challenges in setting up a nano-engineered value chain, which is critical for a new generation of nano-enabled products.     

Photovoltaic solar cells: Choice of materials and production methods

Photovoltaic solar cells and modules are produced for:

(i)

large scale power generation, most commonly when modules are incorporated as part of a building (building integrated photovoltaics, BIPV) but also in centralised power stations,

(ii)

supplying power to villages and towns in developing countries that are not connected to the supply grid, e.g. for lighting and water pumping systems,

(iii)

supplying power in remote locations, e.g. for communications or weather monitoring equipment,

(iv)

supplying power for satellites and space vehicles,

(v)

supplying power for consumer products, e.g. calculators, clocks, toys and night lights.

This paper reviews the choice of materials and main methods of manufacture of photovoltaic solar cells and modules that are commercially available.     

Novel Mg-based alloys by selective laser melting for biomedical applications: microstructure evolution,microhardness and in vitro degradation behaviour

Laser-melted Mg-3Zn-xDy (x?=?0, 1, 3, 5?wt. %) alloys were investigated as candidate materials for biodegradable metallic implant applications. The results showed that the α-Mg, MgZn₂ and Mg-Zn-Dy phases were distributed in the Dy-containing alloys. Due to the addition of Dy, the grain size was significantly refined. As the grain size decreased and the second phase content increased, the hardness monotonously increased. The degradation characteristics analysis via immersion testing indicated that the degradation rate of the laser-melted Mg-3Zn-1Dy alloys was remarkably reduced, evidenced by the corresponding lower average hydrogen evolution rate. Consequently, the Mg-3Zn-1Dy was considered to be a promising candidate for implant applications, due to the appropriate rate of mechanical integrity loss during degradation. Overall, the mitigated degradation rate was attributed to the refined grains, the homogeneous microstructure as well as a certain amount of second phase produced during the process of selective laser melting.     

Exploration,exploitation and innovation performance: disentangling the evolution of industry

The evolution of industry has recently attracted the attention of scholars studying the relationships between exploration and exploitation strategies and innovation performance. Surprisingly, although extant research has already acknowledged its multidimensional character, it has only been analyzed in an aggregate fashion. In this paper, we distinguish two components of the evolution of industry, the pace of market evolution and the pace of technology evolution, and we elaborate on their different impacts in the context of exploration and exploitation strategies. More precisely, we argue that while a rapid pace of technology evolution has opposite impacts on the relationships between exploration (positive), exploitation (negative) and innovation performance, a rapid pace of market evolution positively affects both exploration and exploitation. Our findings provide substantial support for our prediction using a large panel of Spanish innovating firms for the period 2008–2012.     

IF钢铁素体区热轧和退火过程中织构的演变

研究了一种Ti—IF（Interstitial—free）钢在铁素体区热轧和退火过程中织构的变化．由于轧制过程摩擦的影响,热轧织构和退火织构在厚度方向上都有很大的差异．在钢板的表层,热轧织构的主要组分是{110}（001）,退火后表层的铁素体晶粒没有发生再结晶,该组分转变为（001）（110）;在试样的中心和1／4面,热轧织构组分主要是较弱的（111）／／ND（板法向）织构和部分（110）／／RD且在{001}（110）处最强;退火后中心面上的晶粒发生了完全再结晶,{001}组分转变为（111）／／ND组分使（111）／／ND织构成为唯一织构组分且在{111}（112）处最强．     

Scientific imaginaries and science diplomacy: The case of ocean exploitation

As technologies of ocean exploitation emerged during the late 1960s, science policy and diplomacy were formed in response to anticipated capabilities that did not match the realities of extracting deep‐sea minerals and of resource exploitation in the deep ocean at the time. Promoters of ocean exploitation in the late 1960s envisaged wonders such as rare mineral extraction and the stationing of divers in underwater habitats from which they would operate seabed machinery not connected to the turbulent surface waters. Their promises coincided with others' fears that nuclear weaponry would be placed on the seabed. Those who lacked the technological capability to extract minerals from the seabed also had concerns that other nations would exploit their resources. Scientific imaginaries caused uncertainty in the international community—especially in the “Global South.” The UN called the “Law of the Sea” conferences to mediate emerging geopolitical tensions caused by these imaginaries of exploitation of ocean resources. These conferences became a site where lawmakers projected futures rather than merely responding to past or present dilemmas. Diplomats' negotiations, with their basis in anticipation of the future uses of science and technology, reveal the role of scientific imaginaries within complex negotiations. Here, we see the impact of the distinction (or blurring) of the real and the imagined on the balance of relations between Global North and South increasing global imbalances of resources and power. This article's analysis of such scientific diplomacy provides a valuable example of the power of scientific imaginaries to have a global impact.     

Glue-assisted grinding exfoliation of large-size 2D materials for insulating thermal conduction and large-current-density hydrogen evolution

Two-dimensional (2D) materials have many promising applications, but their scalable production remains challenging. Herein, we develop a glue-assisted grinding exfoliation (GAGE) method in which the adhesive polymer acts as a glue to massively produce 2D materials with large lateral sizes, high quality, and high yield. Density functional theory simulation shows that the exfoliation mechanism involves the competition between the binding energy of selected polymers and the 2D materials which is larger than the exfoliation energy of the layered materials. Taking h-BN as an example, the GAGE produces 2D h-BN with an average lateral size of 2.18 μm and thickness of 3.91 nm. The method is also extended to produce various other 2D materials, including graphene, MoS₂, WS₂, Bi₂O₂Se, mica, vermiculite, and montmorillonite. Two representative applications of thus-produced 2D materials have been demonstrated, including 2D h-BN/polymer composites for insulating thermal conduction and 2D MoS₂-based electrocatalysts for large-current-density hydrogen evolution, indicating the great potential of massively produced 2D materials.     

复合电沉积制备（Ni-Mo）-TiO2电极及其电催化析氢性能

为开发新型廉价高效的析氢材料,用恒电流复合电沉积方法制备了(Ni-Mo)-TiO2复合电极,讨论了TiO2悬浮量和电沉积时间对电极催化析氢性能的影响.用XRD和SEM对电极的晶体结构和表面形貌进行了表征,以稳态极化曲线对电极的催化析氢特性进行了评价.结果表明,(Ni-Mo)-TiO2电极是纳米TiO2粒子相和纳米晶Ni-Mo固溶体相构成的复合电极.电极具有较高的催化析氢活性.在25℃、0.5mol.dm-3H2SO4溶液中其表观交换电流密度是Ni-Mo合金电极的2.6倍,是Ni电极的60倍.在电流密度为100mA·cm-2时,电极电势相对于Ni-Mo电极正移了120mV,相对于Ni电极正移了542mV.催化活性的提高源于反应机理的改变,表观活化吉布斯自由能相对于Ni-Mo合金电极降低了24.48kJ·mol-1.     

Generation and sensing of membrane curvature: Where materials science and biophysics meet

We briefly introduce the biological background of biomembrane curvature generation and sensing. Using several examples from our own research, we illustrate how computational models of different resolution (atomistic, coarse-grained and continuum mechanics) can be used to dissect the underlying physical principles that govern peptide/protein-membrane interactions, which ultimately shape the mechanism and biological function of biomembrane remodeling and curvature sensing. Through these discussions, we hope to highlight that this research area can greatly benefit further cross talks between the materials and biophysics communities. Important mechanistic insights can be obtained by studying model systems using approaches established in the soft matter community, such as the analysis of phase behavior. On the other hand, defining the principles that govern these biological processes can inspire the design of novel strategies that organize non-biological molecules for materials applications. Current challenges in the computational methodologies are also briefly discussed.     

Transient evolution of weakly nonlinear sloshing waves: an analytical and numerical comparison

The problem of water waves generated in a horizontally oscillating basin is considered, with specific emphasis on the transient evolution of the wave amplitude. A third-order amplitude evolution equation is solved analytically in terms of Jacobian elliptic functions. The solution explicitly determines the maximum amplitude and nonlinear beating period of the resonated wave. An observed bifurcation in the amplitude response is shown to correspond to the elliptic modulus approaching unity and the beating period of the interaction approaching infinity. The theoretical predictions compare favorably to fully nonlinear simulations of the sloshing process. Due to the omission of damping, the consideration of only a single mode, and the weakly nonlinear framework, the analytical solution applies only to finite-depth, non-breaking waves. The inviscid numerical simulations are similarly limited to finite depth.     

Solar energy technology: Knowledge,awareness, and acceptance of B40 households in one district of Malaysia towards government initiatives

Various initiatives have been planned and implemented by the Government of Malaysia to increase the lower 40% household income known as “B40”. Among these was the solar photovoltaic (PV) project publicly known as “MySuria,” which was presented by the 6th Prime Minister of Malaysia in Budget 2017. As classified by the Department of Statistic Malaysia (DSoM), B40 is a household group that earns a monthly income of RM3,855 and below. It is a group of people who have low wealth and non-financial asset ownership and desperately needed governmental and non-governmental organizations (NGOs) assistance to survive and very vulnerable to economic shocks. This study was conducted to identify the B40 households' level of basic science knowledge, awareness, and acceptance to use solar photovoltaic (PV) energy technology to generate extra income. A set of questionnaires comprises demographic information, awareness, and acceptance to utilizing solar PV technology, as well as a short test about the basic science of solar energy, were distributed to selected respondents. The respondent was composed of one hundred B40 working individuals in the public and private sectors around the Tanjong Malim district. Since this research is intentionally done to identify the specific group interests with no intention to generalized the data, the group population was purposefully sampled to achieve the research's objective. It was found that 43% of respondents have a tertiary education (diploma or degree), 70% were married, and 90% were youth (under 40 years old). The findings of this study also revealed that although 80% of respondents have basic knowledge of science, their level of awareness about solar energy technology and its use was at the average score. However, the respondents showed their high level of acceptance towards the government's initiative in using solar energy technology to increase their household incomes. Additionally, the study also discovered that the B40 group in Tanjung Malim district is highly engaged in the changes brought by the new technology product to their society that would benefit them. On top of that, the respondents gave a full-fledged commitment to use, promote, and educate their families in solar energy technology.     

Micromechanical constitutive modelling of granular media: evolution and loss of contact in particle clusters

Micromechanical constitutive equations are developed which allow for the broad range of interparticle interactions observed in a real deforming granular assembly: microslip contact, gross slip contact, loss of contact and an evolution in these modes of contact as the deformation proceeds. This was accomplished through a synergetic use of contact laws, which account for interparticle resistance to both sliding and rolling, together with strain-dependent anisotropies in contacts and the normal contact force. By applying the constitutive model to the bi-axial test it is demonstrated that the model can correctly predict the evolution of various anisotropies as well as the formation of a distinct shear band. Moreover, the predicted shear-band properties (e.g. thickness, prolonged localisation, void ratio) are an even better fit with experimental observations than were previously found by use of previously developed micromechanical models.     

The evolution of family level sales forecasts into product level forecasts: Modeling and estimation

It is frequently the case that sales forecasts are available at the detailed product level for only a relatively short time horizon. For the rest of the forecast horizon, only aggregate sales forecasts at the product family level are available. The problem addressed in this paper is how to fit a forecast simulation model to a history of these aggregate and disaggregate forecasts. Our approach to develop such a model is to combine a forecast update model with a forecast disaggregation model. The forecast update model is called the Martingale model of forecast evolution. The parameters of the two models must be estimated from historical forecast data. It is this statistical parameter estimation problem that occupies the major part of our investigation. We recommend an estimation technique based on the method of moments.     

Linking the bottom-up and top-down evolution of regional innovation systems to policy: organizations,support structures and learning processes

The literature is ambiguous about whether regional innovation systems (RIS) evolve bottom-up or top-down. This is reflected in RIS policies, which tend to focus on either development of the actor level, i.e. organizations in a RIS, or the system level, i.e. the support structure for innovation. Here, we analyzed a Norwegian RIS policy programme, the Programme for Regional R&D and Innovation (VRI), which aimed to combine both approaches. We found that VRI mainly developed the support structure for innovation and that learning outcomes from VRI involvement in organizations differed between the involved actor groups. This is particularly so for RIS development in regions inexperienced with support structure development prior to VRI involvement. Conversely, in regions with well-functioning support structures prior to VRI, the focus was most beneficially on stimulating learning at the actor level. We argue that future research should investigate mechanisms and interlinkages between the two levels and especially their regional particularities.     

Exploring and visualizing spatial-temporal evolution of patent collaboration networks: A case of China's intelligent manufacturing equipment industry

With the integration of intelligent manufacturing (IM) technology and the manufacturing industry, the intelligent manufacturing equipment industry (IMEI) has become the focus of a new round of industrial revolution. This integration has led to a new revolution in the manufacturing industry and is key to transforming China into a manufacturing country with international competitiveness. However, China's IMEI is in the development stage, thus presenting a major challenge to it becoming a competitive core industry. Therefore, there is an urgent need to explore the IMEI patent collaboration network and analyze its evolutionary characteristics, which can improve not only the innovation ability of network organizations but also the overall competitiveness of the IMEI. This study employs social network analysis (SNA) to study the evolution of the patent collaboration network of China's IMEI. The results show that the number of co-patents for the IMEI field in China has obvious stage characteristics, the collaborative innovation patterns adopted by different provinces vary, and the State Grid has a strong influence on the network. The scale of the patent collaboration network is gradually expanding, exhibiting a “small-world” structure. Jiangsu mainly innovates through intra-provincial collaboration. Provinces such as Beijing, Guangdong and Shandong are more inclined to inter-provincial collaboration.     

Coupling and evolution mechanism of infrastructure mega-projects complex ecosystem: Case study on Hong Kong-Zhuhai-Macao Bridge

Infrastructure mega-projects (IMP), which involve complex interactions and feedback, have more significant impact on economic, social, and other systems. This paper proposes a concept—the IMP complex ecosystem—to analyze IMP from a broad perspective of organic links across engineering, social, economic, and resource environments. Moreover, this paper proposes the theoretical concept, framework, and functions for the IMP complex ecosystem based on complex ecosystem theory. First, the coupling process between IMP complex ecosystem subsystems is analyzed through material flows, energy flows, information flows, and value streams. Second, a logistic model of the IMP complex ecosystem is proposed by analyzing the evolution conditions and motivations. Third, the evolution pattern of the IMP complex ecosystem is determined. Fourth, the positive evolution strategy of the IMP complex ecosystem based on dissipative structure theory and the influencing factors of the evolutionary process is introduced. Finally, the Hong Kong-Zhuhai-Macao Bridge and Sousa chinensis are used as the case study. This paper also analyzes the coupling structure on the complex ecosystem of the Hong Kong-Zhuhai-Macao Bridge and investigates the coupling and evolution mechanism application of the IMP complex ecosystem on Sousa chinensis protection for the Hong Kong-Zhuhai-Macao Bridge project.     

The evolution of short fatigue crack lengths and crack density: two approaches

The density and size of short cracks on the surface of 1Cr18Ni9Ti stainless steel smooth specimens during low cycle fatigue are investigated using a replica technique. The density and size data are analysed from two different observation policies, i.e. Policy I pays attention to the whole specimen test piece and Policy II is related to an ‘effective short fatigue crack criterion’, which pays attention to the dominant crack (DC) initiation zone and the zones ahead of the DC tips. The results reveal that both the crack density and crack size evolution exhibit a specific character during the microstructural short crack (MSC) and physical short crack (PSC) stages. The Policy I‐based observations exhibit an increasing density and little scatter of the density data. The increasing density violates the general test observation of decreasing collective crack effects in the PSC stage. The little scatter is too small to reflect the intrinsic scatter of fatigue properties. Both the crack density and crack size evolution from this policy show little relationship with the intrinsic localization of fatigue damage. However, Policy II‐based observations show an increasing crack density and an increasing density scatter in the MSC stage. The density and scatter reach their maximum values at the transition point between the MSC and PSC stages. Then, they decrease with fatigue cycling in the PSC stage and tend to their saturation values when the DC size is above about 500 μm. This behaviour shows a good agreement with the general test observations of decreasing collective crack effects and growth rate scatter in the PSC stage. Further, both approaches exhibit an evolutionary positively skewed crack size distribution, and an increasing difference between the average crack length and the DC length in the PSC stage, indicative of decreasing collective crack effects. A three‐parameter Weibull distribution (3‐PWD) is appropriately used to describe the crack sizes and a 6.5 to 7.6 μm value of location parameter of the distribution is obtained to reflect a minimum value for the initial cracks. It is worth noting that Policy I‐based observations show an increasing positively skewed crack size distribution, an increasing scatter of the size data and a decreasing shape parameter of the 3‐PWD. This represents an increasing collective crack effect and an increasing irregularity of interactive cracks, which violates the general test observations. In contrast, Policy II‐based observations exhibit a decreasing positively skewed size distribution shape and an increasing (from <1 gradually to >1) shape parameter of the 3‐PWD that is in agreement with the general test observations. The increasing shape parameter indicates that the collective crack effects act as an evolutionary process from an initial non‐ordered (chaotic) random state gradually to an independent random state at the transition point between the MSC and PSC stages and then, to a loading history‐dependent random state. This behaviour is in accordance with the evolutionary DC growth behaviour. Therefore, the evolutionary short crack behaviour associated with the intrinsic localization of fatigue damage should be appropriately revealed from the ‘effective short fatigue crack criterion’‐based observations.     

Ternary binder made of CFBC fly ash,conventional fly ash,and calcium hydroxide: Phase and strength evolution

Coal combustion products present a source of aluminosilicate materials for further utilization. The ternary binder studied here is such an example, consisting of circulating fluidized bed combustion (CFBC) fly ash, conventional fly ash and Ca(OH)² activator. The paste yields a compressive strength of 32 MPa after 28 days of standard sealed curing. Volumetric evolution of crystalline and amorphous phases during hydration is quantified using XRD analysis, differential thermal gravimetry, porosimetry and electron microscopy. A micromechanical model is applied to interpret the evolution of compressive strength due to the growing proportions of C-S-H and ettringite in the system. This opens the way for further optimization and utilization of this ternary binder.