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For the drag and heat flux reduction of hypersonic blunt body, a novel combinational spike-aerodisk and channel concept has been proposed. The high pressure air behind the bow shock flows into the channel at the head of the aerodisk, and then sprays out through the lateral jet in the middle of the spike. The Reynolds-averaged Navier-Stokes (RANS) equations coupled with the shear stress transport (SST) k - ω turbulence model have been employed to simulate the flow field. The numerical results reveal that compared with the spike-aerodisk, with the application of the channel, the lateral jet pushes the separated shock wave away from the spike. The range of the recirculation zone between the shear layer and the spike is increased, and the intensity of the reattached shock wave is significantly weakened, so the drag and heat flux reduction properties of the combinational configuration are significantly improved. The influences of the channel convergent half angle and lateral jet location on the flow field, drag and heat flux reduction properties are investigated thoroughly. When the channel convergent half angle is appropriate and the location of the lateral jet is close to the middle of the spike, the drag and heat flux reduction effect becomes better. Besides, with the increase of the Mach number and the decrease of the flying height, the drag and heat flux reduction performance become more significant. In the research range, the combinational configuration in which the convergent half angle is 60° and the lateral jet is located in the middle of the spike has a better overall effect of drag and heat flux reduction, and the effect reaches the best when the Mach number is 6 and the flying height is 20 km. Compared with the spike-aerodisk, the total drag coefficient of the configuration is reduced by 12.95%, and the peak value of Stanton number along the blunt body surface is reduced by 35.19%. • A novel combinational spike-aerodisk and channel concept was numerically investigated. • The combinational concept has better performance in both drag and heat flux reduction. • Effects of channel convergent half angle and lateral jet location on drag and heat flux reduction were studied. • Variation laws of drag and heat flux reduction under different Mach numbers and flight altitudes were analyzed. [ABSTRACT FROM AUTHOR]

• A novel performance-enhancement strategy for SLGHP geothermal system is proposed. • It relies on arousing inter-layer groundwater crossflow in reservoirs of multi-aquifers. • A numerical model is developed to describe and study the enhanced SLGHP system. • Effects of related parameters are comprehensively studied. The super-long gravity heat pipe (SLGHP) is a novel down-hole heat exchanger (DHE), which is in fast-developing and extremely suitable for deep-earth geothermal energy exploitation. The SLGHP itself has very high heat transfer coefficient, making the poor heat transfer capability of the surrounding geothermal formulations become the bottleneck constraining the overall performance of the SLGHP geothermal system. Inspired by the enhancing effect of the flowing groundwater in the aquifers on the thermal performance of the traditional DHE system, the present work proposes a heat transfer enhancement strategy based on arousing inter-layer crossflow in wellbore-connected multi-aquifers for the SLGHP geothermal system. A detailed numerical study is conducted to examine the effects of key parameters like the permeability and thickness of aquifers, the distance and pressure difference between aquifers. It is found that: i) a larger aquifer permeability leads to larger heat extraction rate of the SLGHP, but the heat extraction rate increment decreases due to the marginal effect when the aquifer permeability is larger than 10−12 m2; ii) a larger pressure difference improves the heat extraction of the SLGHP, the groundwater flow pattern from the deep to the shallow aquifers rather than the reversed pattern is found to be more beneficial due to the geothermal gradient; iii) the distance between aquifers shows a composite impact on the heat extraction performance of the SLGHP. A larger distance not only enlarges the heat transfer area between the SLGHP and the groundwater, but also creates an impeding effect on the heat uptake of SLGHP from the geothermal formation owing to the presentence of temperature-lowered groundwater in the flow path ending-part in the wellbore. In addition, the aquifer's thickness is found to have great impacts on the SLGHP heat extraction rate, and the "cask" effect may be encountered when the thickness difference between the connected aquifers is considerably large. [ABSTRACT FROM AUTHOR]

A recycled solvent-based green synthesis strategy for 2D/3D zeolitic imidazolate frameworks (ZIFs) has been developed to produce functional nanoporous carbons (NPCs) with tuneable morphology, graphitization, N-doping and high porosity via direct pyrolysis. These tailored NPCs show superior supercapacitance performance over typical NPC derived from MOFs and chemical activation/template-directed methods. [Display omitted] • Two important aspects of green synthesis and improved supercapacitance are reported. • A green synthesis route for ZIF-8 via recycling mother liquors (RMLs) is developed. • Rod-/sheet-/polyhedral-like 2D/3D microstructures are produced with RMLs. • 2D/3D NPCs deliver excellent capacitance values and device-level performance. Carbonized metal–organic frameworks (MOFs)-based nanoporous carbon materials (NPCs) offer attractive activities in electrochemical energy conversion and storage (EECS) applications; however, there is the need for scalable MOFs production under reduced energy/environmental impact. This study reports a green synthesis route for model zeolitic imidazolate framework (ZIF-8) materials via recycling methanol-based mother liquors (ZIF-RML x) under room temperature stirring and their carbonized materials (CZC-RML x) for high-performance supercapacitors. Series of ZIF-RML x samples produced in four recycles offer rod-/sheet-/polyhedral-like 2D/3D microstructures with tuneable internal and external framework and morphological features. Accordingly, CZC-RML x , obtained by direct pyrolysis, with high microporosity and surface area of 1500 m2 g−1 deliver excellent capacitance values of 200–340 F g−1, compared to typical MOFs-derived or chemically activated/templated NPCs, produced via extended chemical processing. Structure-relevant and comparative performance analysis reveal insights for improved charge storage and carbonization-dependent graphitization, nitrogen-doping and microporosity-controlled capacitance characteristics in the CZC-RML x over typical NPCs in literature. The device-level performance with a long-term durability over 21,000 cycles is demonstrated. The practical potential of CZC-RML x is further evaluated by fabricating solid-state cells and their parallel and series circuit combinations result in overall capacitance and voltage boost to 450 F g−1 and 2.4 V, respectively. [ABSTRACT FROM AUTHOR]

The study of high-speed rotating matter is a crucial research topic in physics due to the emergence of novel phenomena. In this letter, we combined cranking covariant density functional theory (CDFT) with a similarity renormalization group approach to decompose the Hamiltonian from the cranking CDFT into different Hermite components, including the non-relativistic term, the dynamical term, the spin-orbit coupling, and the Darwin term. Especially, we obtained the rotational term, the term relating to Zeeman-like effect, and the spin-rotation coupling due to consideration of rotation and spatial component of vector potential. By exploring these operators, we aim to identify novel phenomena that may occur in rotating nuclei. Signature splitting, Zeeman-like effect, and spin-rotation coupling are among the potential novelties that may arise in rotating nuclei. Additionally, we investigated the observability of these phenomena and their dependence on various factors such as nuclear deformation, rotational angular velocity, and magnetic field-like strength. [ABSTRACT FROM AUTHOR]

Lane-changing control is a crucial task to regulate the traffic flow in the intelligent transportation system efficiently, and manipulating the lane-changing maneuvers for many vehicles optimally and simultaneously in a congested traffic environment is a challenge. This study formulates a lane-changing model where the traffic lanes are discretized into cells, considers both mandatory lane-changing and discretionary lane-changing maneuvers and proposes a novel approach based on a deep Q-network with a request–respond mechanism. The modeled lane-changing system is divided into isolated and symmetry groups, then independent Q-learning and the concept "central agent" are integrated to simplify the training process. In the proposed approach, these groups can be classified into two categories: request group and respond group. The request group and respond group are trained separately during the training process. Specifically, the request group trains agents with only considering the states of the group, while the respond group also evaluates the superimposing actions (i.e., the request message) from the request group besides the states of the group. The execution process is also treated the same decentralized way as the training process. Then, the baselines such as a rule-based method, a game theory-based decomposition algorithm and a simple deep Q-learning method are compared with the proposed approach. Results reveal that the proposed approach performs as well as the game theory-based decomposition algorithm and outperforms the other two in terms of lane-changing efficiency. However, the computational time of the proposed approach in the execution process is far less than the game theory-based decomposition algorithm, especially in a congested traffic environment. • A cellular lane-changing model is constructed mathematically. • A deep Q-learning method with the concept of "central agent" is implemented. • The "virtual agent" concept is introduced to train the group. • A novel deep Q-learning approach with a request and respond mechanism is proposed. • Baselines are compared and the proposed approach shows great potential. [ABSTRACT FROM AUTHOR]

In drug delivery systems, graphene materials are promising drug carriers. Drug molecules are loaded on graphene through π-π interaction between graphene and benzene ring structure, which is widely found in organic drug molecules. Then the drug molecules are released under different conditions, such as different environmental pH, at lesion site. In the application, the adsorption and desorption between benzene ring structure in drug molecules and graphene play a key role. Herein, an experimental method for measuring the adhesion force between a single phenyl and graphene is proposed, and the adsorption and desorption mechanical properties of a benzene ring structure on graphene surface at different environmental pH are firstly measured. The experimental results show that the adhesion force decreases with the increase of environmental pH. Moreover, molecular dynamics simulations show that the influence of pH on adhesion force is mainly realized by changing the electrostatic potential distribution on graphene surface, and the interaction force between a single benzene and graphene changes from attractive to repulsive with the increase of environmental alkalinity. In addition, a molecular dynamics model for the dynamic adsorption and desorption capacities of benzene molecules on graphene surface at different quantity of ions is established. Benzene molecules can achieve full adsorption on the surface of graphene when there are 10 and 20 hydrogen ions. And benzene molecules can achieve full desorption on the surface of graphene when there are 10 and 20 hydroxide ions. [Display omitted] [ABSTRACT FROM AUTHOR]

Stable water in water (W/W) emulsions of guar rich droplets dispersed in an amylopectin rich continuous phase (G/A) and the inverse (A/G) can be achieved by adding gelatin and inducing microphase separation of the latter by cooling. In this research, the effect of gelatin on the emulsion stability was further studied by storing the emulsions at 10, 20 and 25 °C. The visual aspect, the microstructure, and the viscosity of the emulsions were investigated at different times during storage at different temperatures and pH. It was found that depending on the conditions, the gelatin phase wetted the interface or formed small discrete microdomains that adsorbed at the interface and dispersed in the bulk phases. The observed differences in morphology and stability are related to the interplay of the rates of aggregation, phase separation of gelatin, which itself depend on the gelatin concentration, temperature and pH. Emulsions could be prepared in this manner that were stable for at least one week and remained visually homogeneous. We believe that this is a promising method to stabilize W/W emulsions as long as the components of the emulsion are incompatible with aggregated gelatin. • Water in water (W/W) emulsions were stabilized by adding gelatin. • Microphase separation of gelatin in the W/W emulsions was induced by cooling. • Either a gelatin layer or discrete gelatin domains formed at the W/W interface. • The stability is related to the rates of gelatin aggregation and phase separation. • The stability could be tuned by gelatin concentration, temperature and pH. [ABSTRACT FROM AUTHOR]

SnO 2 has a high specific capacity, low price, and a wide range of sources, but the anode material made from SnO 2 is extremely unstable due to volume expansion. In this work, SnO 2 nanoparticles were prepared using Sn-MOF as the precursor and compounded with sunflower seed shell porous carbon (SSSC) in a solvothermal manner to obtain a high-performance lithium-ion battery anode. The size of SnO 2 nanoparticles prepared using Sn-MOF as the precursor is uniform, only 10–20 nm, which can fully alleviate the volume expansion of SnO 2. On this basis, MOF-SnO 2 is anchored onto the porous carbon of the sunflower seed shell, which can provide more lithium insertion sites and further inhibit the volume expansion of SnO 2. The composite anode in this article has a stable specific capacity of 1050.8 mAh g−1 after 100 cycles at a magnification of 0.2C and a stable specific capacity of 512.9 mAh g−1 after 100 cycles at a magnification of 2C. [Display omitted] • SnO 2 nanoparticles were prepared by using tin-based metal organic framework as template. • SnO 2 nanoparticles composited with sunflower seed shell porous carbon were used as anode materials. • The composite material maintains 1050.2 mAh g–1 after 100 cycles at 0.2 C for LIB. [ABSTRACT FROM AUTHOR]

Shock drag and aeroheating are major problems faced by hypersonic vehicles. This study proposes a novel three-dimensional model combining spike-aerodisk with a bleed air channel featuring multiple lateral nozzles for drag and aeroheating reduction. The high-temperature and high-pressure air at the stagnation point of the aerodisk is introduced into the channel and ejected laterally through multiple nozzles to modify the flow field structure and reduce drag and aeroheating. In contrast to previous research employing a two-dimensional axisymmetric assumption, our innovation considers the structure of the exit nozzles and the spacing between nozzles. Due to multiple lateral nozzles, the connection thickness between nozzles can lead to asymmetric flow phenomena. Three-dimensional flow field simulation has been employed with the Reynolds-averaged Navier-Stokes (RANS) equations coupled with the shear stress transport (SST) k-ω turbulence model. The effects of the convergence half-angle of the channel inlet, the divergent angle of the nozzle, and the nozzle position on modifying the characteristics of the flow field are studied. Increasing the convergence half-angle of the channel inlet can further push away the reattachment shock, but when it exceeds 60°, the drag reduction performance degrades. Reducing the divergent angle of the nozzle and increasing the number of nozzles can reduce the drag coefficient and the peak value of the Stanton number. However, when the divergent angle is reduced to 10°, the performance of reducing drag and aeroheating is weakened. In the range of research parameters, when the convergence half-angle is 60°, the divergent angle is 15°, and the nozzles are located in the middle of the spike, compared with the plain spike-aerodisk model, the drag coefficient and peak Stanton number of the combined model are further reduced by 17.8 % and 34.8 %, respectively. Our findings confirm that a multi-nozzle can effectively reduce drag and aeroheating while the channel structure is viable in practice. • A new model of lateral jet without gas source is studied by 3-D numerical simulation. • The gas for the lateral jet is coupled with the outside flow. • A distribution form of multiple lateral nozzles is proposed. • A realistic 3-D simulation is conducted, enhancing its practical applicability. [ABSTRACT FROM AUTHOR]

0.75BiFeO 3 -0.25BaTiO 3 (0.75BF-0.25BT) ceramics have been widely studied because of their high Curie temperature, good thermal stability and lead-free trait. The evolution of domain motion during electric poling and thermal depoling processes is closely related to the piezoelectric properties and thermal stability of ferroelectric ceramics. Herein, the non-180° domain reversals of 0.75BF-0.25BT ceramics in these two processes were investigated by an in situ XRD technique. The non-180° domain switching fraction during the poling and depoling processes was calculated quantitatively based on the (111) and (11 1 ‾) diffraction peaks. During the poling process, the non-180° domain reversal percentage N 111 and piezoelectric properties increase abruptly when the poling field exceeds 35 kV/cm and then saturate at the electric field of 50 kV/cm (N 111 reaches the maximum value of 59%). The domains switched under the poling electric field of 50 kV/cm are stable below 500 °C. The depoling temperature is sensitive to the domain switching fraction under different poling electric fields, and the ceramics under a strong poling field possess excellent thermal stability and high depolarization temperatures. This work revealed the relationship between the electric properties, domain switching, poling electric field, and depoling temperature in the 0.75BF-0.25BT ceramics, which may pave the way to enhancing the room temperature piezoelectric properties and their thermal stability. [ABSTRACT FROM AUTHOR]

A series of three-dimensional molecular dynamics (MD) simulations was performed to investigate the effect of temperature on the nanoscale deformation behaviour and mechanical properties of c -plane monocrystalline gallium nitride (GaN) under nanoindentation. Simulation results showed that the atomic displacement and strain increased with increasing temperature. Thus, the nucleation and propagation of dislocations in the main slip systems were promoted to intensify the plastic deformation of GaN crystal. Increasing the temperature also contributed to the increase in local phase transition from the wurtzite crystal structure (B4-GaN) to the zinc-blende crystal structure (B3-GaN) and a very evident amorphization of GaN in the indentation zone. Based on the analysis of the load-depth curves, it was found that both the hardness and Young's modulus decreased as the temperature increased. This work can enrich the atomic-level understanding of the effect of temperature on the mechanical response of monocrystalline GaN when subjected to the external loads. [ABSTRACT FROM AUTHOR]

Operational spacecraft are facing a risk of collision with space debris objects. The net capturing method has been proposed to mitigate this risk on spacecraft. The mass-spring model is usually applied for net modeling by discretizing a cable into one or several mass-spring-damper elements in simulation. The absolute nodal coordinates formulation (ANCF) has also been applied to model the net, and this model is able to describe the flexibility of a net using less elements. However, the influence on the net behavior in simulation by the flexibility modeling of a net is not well understood and barely discussed. In this paper, flexibility models of a net are established based on the mass-spring model and the ANCF model,respectively. The influence on the net behavior by the flexibility modeling is, for the first time, analyzed via simulations. Two case studies of capturing a ball and a cube shaped targets are performed. It is found that the flexibility modeling has little influence on the net dynamics in simulation. Finally, the characteristics and benefits of the ANCF model are described and analyzed. A drawback of the ANCF model was found to be its inferior computational performance. [ABSTRACT FROM AUTHOR]

The current investigation applied the invariant manifold technique to study the halo orbits around the libration points in circular restricted three-body problem. Two dominant (leading) directions were considered as dominant motions for the construction of spatial halo orbits, the third direction motion being the slave (following) motion. The dominant motions correspond to four-dimensional invariant manifolds in the phase space. The invariant nonlinear asymptotic relations (i.e. INARs) between the two dominant motions and the slave motion were established, enabling a transformation from the 3-DOF problem into a 2-DOF problem. Application of the INARs are also discussed. Such invariant nonlinear relations in polynomial expansion form could be used as: (I) approximate analytical solutions; (II) topological constraints to obtain more exact numerical solutions with differential correction. General findings in the current research revealed that the nonlinear asymptotic relations among the directions provided an alternative point of view to explore the overall dynamics of halo orbits around libration points with general rules. The effectiveness of the proposed method was also verified by numerical simulations. • Invariant nonlinear asymptotic relations (INARs) between dominant and slave motions are obtained. • The 3D system is reduced into a 2D system by INARs. • Analytical solutions for halo orbits are obtained by INARs. • INARs are used as topological constraints to obtain halo orbit with differential correction. [ABSTRACT FROM AUTHOR]

In this paper, we use a stochastic dynamic programming model to evaluate the impacts of uncertainties on the abatement planning process. By involving the endogenous emission path, we differentiate two types of uncertainties during the planning process, which come from the volatility of the abatement cost and the ambiguity of emission rate. Results suggest that the considered uncertainties influence the decision-making process in several aspects by shaping the abatement path as well as emission path. (1) The impacts vary with the expected value and the level of variance of the uncertainty effects. Uncertainties caused by abatement costs from 0.02 to 0.06 and emission factors from 0.01 to 0.03 increase the total abatement costs around 7% and 5% respectively. (2) Both of these uncertainties can generate precautionary abatement in short-term. Especially during the early stages, the abatement task will be increased by 1% around in each period due to the uncertainties. However such an action will be diminishing as the duration elapses. (3) Both of these uncertainties influence the long-term abatement performances, however, with different forms and mechanisms. With small volatility, the emission rate changes the priority sequence of abatement actions more substantially in the short-term than the emission rate does. (4) The combined uncertainties can behave in a compound way to improve the uncertainty performance in the model. The difference between the emission peaks of conservative and extreme cases is significant with the gap being about 5 million metric ton. These results have potentially important policy implications and can provide a rationale for abatement actions. • We use a stochastic dynamic programming model to evaluate the impacts of uncertainty on the abatement strategy. • We differentiate two types of uncertainties during the planning process. • For both types of the uncertainty precautionary abatement is required at early stage to hedge the future risk. • The level of synergy effect and the hedging effect between the uncertainties depends on how they are combined. [ABSTRACT FROM AUTHOR]

Thermal management of fuel cell vehicles is posing a constant challenge due to the growing installed power of the fuel cell stack and consequent heat-overloaded situations of the radiator. Based on the "time-dependent" idea that considers the fluctuated heat generation and the intermittent heat peak during the journey, a novel thermal management system that employs a heat-peak regulator is proposed in the present work. The heat-peak regulator is a thermal accumulator filled with phase-change material that separately exchanges heat with the fuel cell coolant and the air conditioner refrigerant. It temporarily receives the excess heat that cannot be released out by the radiator when the heat peak occurs; later on, when the heat peak is gone, the heat is transferred to the refrigerant to remove it from the condenser. The system simulations based on the developed thermal models demonstrate that, the thermal runaway of the fuel cell stack can be eliminated or effectively weakened by this novel thermal management system, relying on the amount of the phase-change material filling the heat-peak regulator. In the present study, the 135 s and 250 s thermal runaway durations can be shortened to 0 s and 105 s, respectively, in the standardized New European Driving Cycle and World-wide Harmonized Light Duty Test Cycle under 38 °C summer weather, and the maximum temperature for the latter can be reduced from 89 °C to 83 °C. This work can make a significant contribution towards the solution of thermal management problems of the fuel cell vehicles. • Proposing the "time-dependent" thermal management methodology. • The thermal management system contains a heat-peak regulator. • The heat-overload problem for the radiator of fuel cell stack is properly handled. • The proposed system is analyzed based on a self-developed thermal model. [ABSTRACT FROM AUTHOR]

Carteolol is a commonly-used topical medication for primary open-angle glaucoma. However, long-term and frequent ocular application of carteolol entails its residuals at low concentration in the aqueous humor for a long duration and may exert latent toxicity in the human corneal endothelial cells (HCEnCs). Here, we treated the HCEnCs in vitro with 0.0117% carteolol for 10 days. Thereafter, we removed the cartelolol and normally cultured the cells for 25 days to investigate the chronical toxicity of carteolol and the underlying mechanism. The results exhibited that 0.0117% carteolol induces senescent features in the HCEnCs, such as increased senescence-associated β-galactosidase positive rates, enlarged relative cell area and upregulated p16INK4A and senescence-associated secretory phenotypes, including IL-1α, TGF-β1, IL-10, TNF-α, CCL-27, IL-6 and IL-8, as well as decreased Lamin B1 expression and cell viability and proliferation. Thereby, further exploration demonstrated that the carteolol activates β-arrestin–ERK–NOX4 pathway to increase reactive oxygen species (ROS) production that imposes oxidative stress on energetic metabolism causing a vicious cycle between declining ATP and increasing ROS production and downregulation of NAD+ resulting in metabolic disturbance-mediated senescence of the HCEnCs. The excess ROS also impair DNA to activate the DNA damage response (DDR) pathway of ATM–p53–p21WAF1/CIP1 with diminished poly(ADP-Ribose) polymerase (PARP) 1, a NAD+-dependent enzyme for DNA damage repair, resulting in cell cycle arrest and subsequent DDR-mediated senescence. Taken together, carteolol induces excess ROS to trigger HCEnC senescence via metabolic disturbance and DDR pathway. [Display omitted] • 0.0117% carteolol induces senescence of human corneal endothelial cells (HCEnCs). • The carteolol activates β-arrestin–ERK–NOX4 axis to elevate ROS production. • The elevated ROS impair DNA and impose oxidative stress (OS) on energy metabolism. • The DNA damage elicits senescence of the HCEnCs via DNA damage response pathway. • The OS provokes metabolic disturbance resulting in senescence of the HCEnCs. [ABSTRACT FROM AUTHOR]

The increasing number of satellites for specific space missions is hindering efficient control from the ground stations. In addition, the risk of failing or deteriorating elements in a multi-satellite system (MSS) leads to the uncertainty in its operating environment which challenges traditional centralized planning algorithms. Centralized algorithms depend on one coordinator to overview entire system, which is a single poitn of failure, so if it malfunctional, the MSS may go down. To overcome this problem, a distributed onboard mission planning algorithm based on the Hybrid Dynamic Mutation Genetic Algorithm (HDMGA) is proposed for such MSS. The satellites are considered as autonomous agents which can communicate and negotiate with other satellites. The mission objective is decomposed through the team negotiation procedures, and the local goals are dispatched to the participant satellite. The local planning procedure on each satellite is modeled as local search problems, while the planning problem for entire team is formulated as strongly-coupled distributed optimization problem. The verification shows that the proposed distributed approach can achieve the same results as the centralized approach. The simulation results illustrate that the proposed approach shows superior performance on both computation time and success rate, as compared with other two state-of-the-art distributed mission planning approaches. [ABSTRACT FROM AUTHOR]

Abstract Contact dynamic models for active debris capturing using a net are presented and analyzed using numerical simulations. The contact dynamics are based on two methods: the penalty-based method and the impulse-based method. Both methods apply contact detection algorithms based on the Axis-Aligned Bounding Box. The impulse-based method is, for the first time, being used in a net capturing scenario. Strengths and weaknesses of both models are compared and discussed. Moreover, the results from numerical simulations of target capturing are presented and analyzed to evaluate the effectiveness of the contact dynamic models. It is found that the average difference of bullet trajectories obtained by two models can be restricted within 6% when it compares with the dimension of the net. Highlights • The impulse-based method is proposed for contact dynamics modeling of a net capturing scenario. • The impulse-based method is compared with the penalty-based method using numerical simulations. • The impulse-based method is found suitable by avoiding penetration and a stiff equation system. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to seek the suitable local objectives for each satellite to optimal the global mission allocation strategy with a global utility function. This paper uses a game-theoretical formulation for a multi-satellite system in which the satellites are viewed as a unique unit with their self-interests. To solve the problem, the first is to identify the utility functions for individual satellite, align them to form the global utility function which can represents the allocation requirements. The second is to design the suitable negotiation mechanisms that can be equipped on each satellite so they can pursue the optimization by their own interest. The Utility-based Regret play, the Smoke Signal play, and the Broadcast-based play are proposed as negotiation mechanisms for the team to cooperate under the distributed and decentralized system structure. The simulation results illustrate that using these mechanisms can help this multi-satellite system reaches a near-optimal allocation profile. The effectiveness of proposed mechanisms are demonstrated by comparing their simulation results with several existing mechanisms under different scale of participant number. [ABSTRACT FROM AUTHOR]

In field of drug delivery, graphene is a potential material as drug carrier due to its large specific surface area and excellent chemical stability. Many kinds of drug molecules can be adsorbed on graphene surface through single or multiple benzene ring structures in drug molecules. Graphene loaded with drug molecules needs to be transported to the lesion site through blood. The content of water molecules in blood accounts for 92%. Therefore, the influence of water molecule on adsorption performance cannot be ignored. Here, the influence and mechanism of water molecule on the adsorption properties between benzene molecule and graphene is studied. The adsorption models of benzene molecule on graphene surface in vacuum and water environments are established, respectively. The adhesion energy, adhesion force and stable adsorption position of benzene molecule in two environments are analyzed by molecular dynamics simulation and potential function theory. Moreover, a model of preadsorption of a single water molecule on graphene surface is further presented, which explains the reason of the difference in adsorption performance in vacuum and water environment from the perspective of energy. The preadsorption of water molecule on graphene surface promotes the adsorption of benzene molecule. [Display omitted] [ABSTRACT FROM AUTHOR]

• Compressive properties of 3D graphene are studied by theory and MD simulations. • The unified constitutive relations of three kinds of 3D graphene are derived. • Compressive deformation mechanisms of three kinds of 3D graphene are discussed. • The configuration-property relationships of 3D graphene are elucidated. • Energy absorption capacities of three kinds of 3D graphene are analyzed. Combining molecular dynamics (MD) simulations and continuum modeling, the uniaxial in-plane compressive properties of honeycomb three-dimensional (h3D), triangle-like 3D (t3D) and non-equilateral hexagon 3D (nh3D) graphene are investigated to elucidate configuration-property relationships, and the constitutive relations of three kinds of 3D graphene are derived to evaluate the compressive mechanical properties. Based on theoretical and MD simulation results, it is found that the compressive stress-strain responses of 3D graphene can be divided into five stages. The compressive mechanical properties and deformation mechanisms of each stage are different. When 3D graphene is compressed, graphene sidewalls undergo rotations, bending and buckling deformations, collapses. Because graphene sidewalls of h3D graphene are prone to undergo buckling deformations, there is large locking strain in h3D graphene. For t3D and nh3D graphene, their high plateau stress is attributed to unique configurations. Moreover, we also find that with increasing graphene sidewall width, Young's modulus and plateau stress of 3D graphene gradually decrease. In addition to the above investigations, the energy absorption mechanisms and compression-unloading stress-strain curves of 3D graphene are also studied. It is found that there are extraordinary compression-recovery properties and energy absorption capacities in 3D graphene. Finally, the selection criteria of 3D graphene are proposed. [Display omitted] [ABSTRACT FROM AUTHOR]

Heterostructured Bi 3 O 4 Br/α-Bi 2 O 3 nanocomposites are prepared via in situ one-step self-combustion of ionic liquids. Tetrabutylammonium bromide (TBAB) is employed to be fuel, complexing agent for ionic liquids, as well as the reactant supplying Br for the objective material. The ratio of Bi 3 O 4 Br/α-Bi 2 O 3 can be easily adjusted by controlling the amount of TBAB. The heterojunctions show higher photocatalytic ability towards both azo dye methyl orange (MO) and colorless pollutant phenol. The electron spin resonance (ESR) test and p-nitro blue tetrazolium chloride (NBT) degradation result indicate that generation amounts of superoxide anion radicals ( O 2 − ) over heterojunctions are less than that over pure Bi 3 O 4 Br. Photoelectrochemical measurements show that separation efficiencies of photo-generated electrons and holes are decreased after the combination of Bi 3 O 4 Br and α-Bi 2 O 3 . Work function test and scavenger experiments display that holes play key role for pollutant degradation and the position of holes on α-Bi 2 O 3 is lowered via hybridization. Thus, the enhanced photocatalytic activity over composites can be attributed to the position decline of α-Bi 2 O 3 valence band, thus improving the reactivity of holes in direct oxidation of pollutants. In this case, valence band position is confirmed to be more important than separation efficiency of charge carriers in affecting photocatalytic performance. [ABSTRACT FROM AUTHOR]

This paper presents an onboard autonomous mission re-planning system for Multi-Satellites System (MSS) to perform onboard re-planing in disruptive situations. The proposed re-planning system can deal with different potential emergency situations. This paper uses Multi-Objective Hybrid Dynamic Mutation Genetic Algorithm (MO-HDM GA) combined with re-planning techniques as the core algorithm. The Cyclically Re-planning Method (CRM) and the Near Real-time Re-planning Method (NRRM) are developed to meet different mission requirements. Simulations results show that both methods can provide feasible re-planning sequences under unforeseen situations. The comparisons illustrate that using the CRM is average 20 % faster than the NRRM on computation time. However, by using the NRRM more raw data can be observed and transmitted than using the CRM within the same period. The usability of this onboard re-planning system is not limited to multi-satellite system. Other mission planning and re-planning problems related to autonomous multiple vehicles with similar demands are also applicable. [ABSTRACT FROM AUTHOR]

In this study a thermo-sensitive switching membrane was prepared through grafting, using a click reaction, of an N -isopropylacrylamide (NIPAAm) derivative onto an electrospun poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) fibrous membrane (EPFM). The PPO was first electrospun into a fibrous membrane, then brominated and reacted with NaN 3 to generate the azido-terminated EPFMs. A propargyl-terminated poly( N -isopropylacrylamide) (PNIPAAm) was synthesized and grafted onto the azido-terminated EPFMs. The surface roughness of PPO fibers was increased due to the presence of PNIPAAm grafts, such that the thermoresponse of the static water contact angle (SWCA) of PNIPAAm-grafted EPFMs between 25 and 45 °C was significantly greater than that of the same PNIPAAm grafted on a flat surface. Thermo-sensitive affinity of the membrane with water resulted the average pore dimension responded to temperature changes. Taking advantage of this temperature-responsive affinity, we applied the membranes as protein valves that blocked and released an antibody. At 25 °C, the collection efficiency was 90% for antibody concentrations of up to 5 ng/mL. Increasing the temperature to 45 °C caused the collection efficiency to decrease abruptly, to 7.5%, when the antibody concentration was greater than 1.5 ng/mL. Accordingly, this system of PNIPAAm-grafted PPO fibers functioned as a protein valve, allowing the blocking and release of proteins. [ABSTRACT FROM AUTHOR]

Failure detection, isolation, and recovery is an essential requirement of any space mission design. Several spacecraft components, especially sensors, are prone to performance deviation due to intrinsic physical effects. For that reason, innovative approaches for the treatment of faults in onboard sensors are necessary. This work introduces the concept of agent-based fault detection and recovery for sensors used in satellite attitude determination and control. Its focuses on the implementation of an algorithm for addressing linear drift bias in gyroscopes. The algorithm was implemented using an agent-based architecture that can be integrated into the satellite's onboard software. Numerical simulations were carried out to show the effectiveness of this scheme in satellite's operations. The proposed algorithm showed a reduction of up to 50% in the stabilization time for the detumbling maneuver, and also an improvement in the pointing accuracy of up to 20% when it was applied in precise payload pointing procedures. The relevance of this contribution is its added value for optimizing the launch and early operation of small satellite missions, as well as, an enabler for innovative satellite functions, for instance, optical downlink communication. [ABSTRACT FROM AUTHOR]

Photovoltaic solar array (PVSA) systems are the most widely used method for spacecraft power generation. However, in many satellite missions, the optimum orientation of the PVSA system is not always compatible with that of the payload orientation. Many methods, have been examined in the past to overcome this problem. Up to date, the most widely used active method for large costly satellites is the Solar Array Drive Mechanism (SADM). The SADM serves as the interface between the satellite body and the PVSA subsystem, enabling the decoupling of their spatial orientation. Nonetheless, there exists a research and development gap for such systems regarding low cost micro-satellites. During the literature study of this paper, individual orbital parameters of various micro-satellites have been extracted and compared to the rotational freedom of the corresponding SADMs used. The findings demonstrated that the implemented SADMs are over designed. It is therefore concluded that these components are not tailored made for each spacecraft mission individually, but rather, exhibit a generic design to full fill a majority of mission profiles and requirements. Motivated by the above analysis, the cardinal objective of the current research is to develop a low cost mechanism that will be precisely tailored for the use of a low Earth orbit (LEO) micro-satellite platform orbiting in altitudes of 500 − 1000 km . The design of the mechanism may vary from the existing miniaturized SADMs. For example, the preliminary analysis of the current research suggests, that the conventional use of the slip ring system as the electronic transfer unit can be replaced by a seMI Orientation Unit (MIOU). Systems engineering tools for concept generation and selection have been used. In addition, simulation and mathematical modelling have been implemented on component and system level, to accurately predict the behaviour of the system under various modes of operation. The production and system testing of the prototype has taken place and it has verified that the development of such a system, will aid the power generation of the solar arrays, while having a positive impact on the cost reduction of such satellites. [ABSTRACT FROM AUTHOR]

Space missions have traditionally been controlled by operators from a mission control center. Given the increasing number of satellites for some space missions, generating a command list for multiple satellites can be time-consuming and inefficient. Developing multi-satellite, onboard mission scheduling & planning techniques is, therefore, a key research field for future space mission operations. In this paper, an improved Genetic Algorithm (GA) using a new mutation strategy is proposed as a mission scheduling algorithm. This new mutation strategy, called Hybrid Dynamic Mutation (HDM), combines the advantages of both dynamic mutation strategy and adaptive mutation strategy, overcoming weaknesses such as early convergence and long computing time, which helps standard GA to be more efficient and accurate in dealing with complex missions. HDM-GA shows excellent performance in solving both unconstrained and constrained test functions. The experiments of using HDM-GA to simulate a multi-satellite, mission scheduling problem demonstrates that both the computation time and success rate mission requirements can be met. The results of a comparative test between HDM-GA and three other mutation strategies also show that HDM has outstanding performance in terms of speed and reliability. [ABSTRACT FROM AUTHOR]

By slotting an inlet at the head of the aerodisk, a channel through the spike, and the lateral jet outlet at the middle of the spike, the blunt body with spike-aerodisk can further reduce its aeroheating and drag. In this paper, the numerical simulation method was used to analyze the flow field structure of this spike-aerodisk-channel, the effects of the spike length, the aerodisk diameter, and the channel diameter on the drag and aeroheating performance of this spike-aerodisk-channel configuration were studied. In general, the lateral jet introduced by the channel from the stagnation region of the aerodisk leads to the shear layer separation in advance, pushes the separation shock away from the spike, enlarges the recirculation zone near the blunt body, avoids the interaction between the separation shock and the reattachment shock, increases the distance from the reattachment shock to the surface of the blunt body. The reattachment shock strength of the blunt body is weakened. With increased spike length and channel diameter, drag and aeroheating reduction are improved. With the increase of the diameter of the aerodisk, the aeroheating performance is improved, but the drag reduction performance continues to decline. Compared with the plain spike-aerodisk, the spike-aerodisk-channel is generally conducive to further drag and aeroheating reduction. In the range of research parameters, considering the effect of drag and aeroheating reduction and the structural feasibility, the spike-aerodisk-channel has the best drag and aeroheating reduction performance when the spike length is twice the blunt-body diameter, the ratio of the aerodisk diameter to the blunt-body diameter is 0.3, and the ratio of the channel diameter to the blunt-body diameter is 0.075. Compared with the plain spike-aerodisk of the same size, the aeroheating reduction efficiency is increased by 37.9%, and the drag reduction efficiency is increased by 16.0%. • Drag and aeroheating reduction mechanism of the spike-aerodisk and channel concept under hypersonic conditions was investigated by the numerical simulation. • Three influence factors were analyzed and compared comprehensively. • Combined spike-aerodisk and channel concept is a promising drag and aeroheating reduction technique. [ABSTRACT FROM AUTHOR]

• Differential expressed noncoding RNAs among the healthy controls and the patients with AAA before and after underwent EVAR were detected. • 164 differentially expressed miRNAs, 179 co-differentially expressed lncRNAs, and 440 co-differentially expressed circRNAs were obtained. • lncRNA-miRNA-mRNA ceRNA network included 15 lncRNAs, 63 miRNAs and 57 mRNAs. • CircRNA-miRNA-mRNA ceRNA network included 79 circRNAs, 21 miRNAs, and 49 mRNAs. • AAA patients might be benefit from EVAR based on various pathways and some molecules related with shear stress. The aim of the study was to explore the potential molecular mechanism associated with shear stress on abdominal aortic aneurysm (AAA) progression. This study performed RNA sequencing on AAA patients (SQ), AAA patients after endovascular aneurysm repair (EVAR, SH), and normal controls (NC). Furthermore, we identified the differentially expressed microRNAs (miRNAs), long noncoding RNAs (lncRNAs), and circular RNA (cirRNAs) and constructed competing endogenous RNA (ceRNA) networks. Finally, 164 differentially expressed miRNAs, 179 co-differentially expressed lncRNAs, and 440 co-differentially expressed circRNAs among the three groups were obtained. The differentially expressed miRNAs mainly enriched in 325 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways. Target genes associated with co-differentially expressed genes among the group of SH, SQ, and NC mainly enriched in 66 KEGG pathways. LncRNA-miRNA-mRNA interactions, including 15 lncRNAs, 63 miRNAs and 57 mRNAs, was constructed. CircRNA-miRNA-mRNA ceRNA network included 79 circRNAs, 21 miRNAs, and 49 mRNAs. Among them, KLRC2 and CSTF1, targeted by miR-125b, participated in cell-mediated immunity regulation. MiR-320-related circRNAs and SATB1-AS1 serving as the sponge of miRNAs, such as has-circ-0129245, has-circ-0138746, and has-circ-0139786, were hub genes in ceRNA network. In conclusion, AAA patients might be benefit from EVAR based on various pathways and some molecules, such as miR-125b and SATB1-AS1, related with shear stress. [ABSTRACT FROM AUTHOR]

Aureobasidium pullulans is an increasingly attractive host for bio-production of pullulan, heavy oil, polymalic acid, and a large spectrum of extracellular enzymes. To date, genetic manipulation of A. pullulans mainly relies on time-consuming conventional restriction enzyme digestion and ligation methods. In this study, we present a one-step homologous recombination-based method for rapid genetic manipulation in A. pullulans . Overlaps measuring >40 bp length and 10 μg DNA segments for homologous recombination provided maximum benefits to transformation of A. pullulans . This optimized method was successfully applied to PKSIII gene (encodes polyketide synthase) knock-out and gltP gene (encodes glycolipid transfer protein) knock-in. After disruption of PKSIII gene, secretion of melanin decreased slightly. The melanin purified from disruptant showed lower reducing capacity compared with that of the parent strain, leading to a decrease in exopolysaccharide production. Knock-in of gltP gene resulted in at least 4.68-fold increase in heavy oil production depending on the carbon source used, indicating that gltP can regulate heavy oil synthesis in A. pullulans . [ABSTRACT FROM AUTHOR]

A tethered-net is a promising method for space debris capturing. However, its deployment dynamics is complex because of the flexibility, and its dependency of the deployment parameters is insufficiently understood. To investigate the deployment dynamics of tethered-net, four critical deployment parameters, namely maximum net area, deployment time, traveling distance and effective period are identified in this paper, and the influence of initial deployment conditions on these four parameters is investigated. Besides, a comprehensive study on a model for the tethered-net based on absolute nodal coordinates formulation (ANCF) is provided. Simulations show that the results based on the ANCF modeling method present a good agreement with that based on the conventional mass–spring modeling method. Moreover, ANCF model is capable of describing the flexibility between two nodes on the net. However, it is more computationally expensive. [ABSTRACT FROM AUTHOR]

Plasma-activated water (PAW) is a promising nonthermal technology in food preservation and food safety. The inactivation efficacy of PAW was investigated against Saccharomyces cerevisiae CICC 1374 inoculated on grape berries. PAW30 and PAW60 were obtained by activating water with plasma for 30 and 60 min, respectively. Grapes were directly treated with PAW, and a 0.38- to 0.53-log CFU/ml reduction of S. cerevisiae was achieved in a time-dependent manner (P < 0.05). The oxidation-reduction potential and pH values of PAW30 and PAW60 were also in a time-dependent manner (P < 0.05). Grape quality assessment demonstrated no significant change in surface color and total anthocyanin content after 30 min of PAW60 treatment (P > 0.05). Although grape quality was unaffected by PAW in this study, this technology should be optimized to enhance inactivation efficiency. [ABSTRACT FROM AUTHOR]

We specify a general model of the dynamic abatement technology adoption process and show how the accumulated experience among them can alter the adoption timing. Learning-by-doing (LBD) effect is considered to describe the reduction of the costly price to the adoption. Moreover, spillovers effect which reflects how accumulated experience can be shared among different technologies, is integrated into the learning process. To ensure the specification convincing, some reasonable assumptions are considered such as one abatement technology must conduct its own experience in order to realize the spillover. Besides, to investigate how the abatement process is influenced by the technology allocation under the spillovers effect, an endogenous emission path is considered to necessitate a meaningful optimization problem. Finally, apart from obtaining some basic properties of the model, we implement an empirical study to verify the effectiveness of the model. Data from the iron industry in China is used to specify the process, which can highlight the spillovers effect among different technologies from a sector angle. In the results, we find that intrinsic mechanism in the model results in the interplay among abatement coefficient, spillover factor and the growing rate of the emission etc. Collaborative relationships between variables are discussed as well. [ABSTRACT FROM AUTHOR]

As CO 2 emissions are quantified by allowances and traded in markets, wise trading strategies will bring emitting companies higher profits or lower costs. Based on the big data of Community Independent Transaction Log (CITL), this article hereby presents a micro study on the emitting companies' efforts in increasing profits and saving costs during the allowances trading in the first two phases of the European Union Emission Trading Scheme (EU ETS). The efforts are measured by an after-action factor of trading performance, which is built on a series of behaviour and monetary variables. By comparison, demanders of the emitting companies are more inclined to reach a higher trading performance, while that inclination is heterogeneous among the suppliers. In addition, emitting companies with lower emission levels had a better trading performance. With a higher proportion of low-emitting companies, the manufacturing sector had a better trading performance than the energy sector. The effect of the trading requirement on trading performance are investigated via a quantile regression mode. Results suggest that: (1) the selling requirement of suppliers has a positive effect on their trading performance, while the effect becomes weaker when the selling requirement increases; (2) the buying requirement has a positive effect on the demanders' trading performance only when the requirement is high, and the effect becomes stronger as the requirement increases; and (3) when the buying requirement is at a lower level, demanders' trading performance becomes worse as the requirement grows. The conclusion is that the emission level, industrial sector and trading requirement do have influences on the trading performance of emitting companies in emission trading. [ABSTRACT FROM AUTHOR]

Molecular dynamics (MD) simulations have been performed to investigate the diffusion properties of hydrogen (H) atoms in body-center-cubic (bcc) iron (Fe) with point defects, i.e., vacancies (Vs) and self-interstitial atoms (SIAs). Firstly, the binding energies of a H atom to a H/SIA-H cluster have been calculated by molecular statics simulations. The results show that single-H diffusion should be the major diffusion mechanism in perfect bcc Fe and bcc Fe with SIAs, but for bcc Fe with Vs, results from literatures show that multi-H diffusion should be taken into account. Further, the mean squared displacements method has been employed to determine the diffusivities and diffusion energy barriers of single-H at different temperatures in perfect bcc Fe. The diffusion energy barrier varies with the temperature. Furthermore, the H diffusion properties with different point defect concentrations have also been demonstrated, which showed that diffusivities reduce as the point defect concentration increases and the influence of point defects reduces as the temperature increases. Especially, SIAs exhibit negligible effect when the temperature is higher than 600 K. [ABSTRACT FROM AUTHOR]

The Sichuan-Tibet Railway traverses the Qinghai-Tibet Plateau in China, where giant landslides occur frequently and densely. Accurately assessing the velocity, runout distance, and influenced area of the potential landslides is one of the nonnegligible scientific and technical issues. This study establishes a dynamic model for the landslide runout assessment along the Sichuan-Tibet Railway. The proposed model is based on the shallow water theory and takes into account the mechanism that the friction is weakening with the increase of velocity, the finite difference method is used to solve the governing equations, and the ideal one-dimensional dam break experiment was used to verify the shock-capturing capacity of the numerical methods. The Lagang ancient landslide, only 500 m away from the Jiacha Station of the Sichuan-Tibet Railway, represents the typical environment and development pattern of landslides in this region. Therefore, the proposed model is applied to discuss its effects on the landslide dynamic process and deposit patterns. Besides, 75 sets of numerical experiments were further carried out to explore the sensibility of the three parameters including peak friction coefficient μ p , steady friction coefficient μ s , and critical velocity V c in this model. The results indicate that μ s determine the lower limit of the friction coefficient, which significantly impacts the landslide runout distance; μ p is mainly acting at the initial and final stage and has less influence on the landslide dynamic. By contrast, V c is the most significant. When the V c is small, the landslide can quickly reach the threshold velocity after the initial, and the dynamic process has a small correlation with the μ p ; when the V c is large, the landslide is difficult to reach the threshold, and the mobility will be limited. It should be noted that the materials, lithology, strength, and micro-cracks of landslides mass formed under the special geological, geomorphic, and climatic conditions in this region may affect the input values when using the friction weakening model on landslides risk assessment. • Established a numerical method for landslide risk assessment in the Sichuan-Tibet railway area • The parameters sensitivity of the resistance weakening model was discussed based numerical tests • Provides a calibration basis and range for the parameters required to apply the model [ABSTRACT FROM AUTHOR]

Autonomous cluster operation such as cluster reconfiguration is one of the enabling technologies for fractionated spacecraft. By virtue of the multi-agent system theory, this paper presents an organizational architecture for fractionated spacecraft, which not only enables autonomous cluster operations but also facilitates its non-traditional attributes. Within this organizational architecture, a decentralized framework is proposed to solve cluster reconfiguration problems based on primal and dual decomposition, where subgradient methods are adopted to include reconfiguration cases with non-differentiable objectives. Two typical constraints are considered: final configuration constraints representing coupling variables and collision avoidance constraints representing coupling constraints, both of which are non-convex. General schemes are proposed to convexify those constraints via the linearization and convex restriction technology. Then final configuration constraints are tackled by primal decomposition, while collision avoidance constraints by dual decomposition. To the end, multi-level primal and dual decompositions are employed to solve reconfiguration problems with both coupling variables and coupling constraints. For illustration an example of in-plane cluster reconfiguration is solved and compared with the centralized approach the solution is optimal. [ABSTRACT FROM AUTHOR]

This paper provides an update of the Delfi nanosatellite programme of the Delft University of Technology (TU Delft), with a focus on the recent in-orbit results of the second TU Delft satellite Delfi-n3Xt. In addition to the educational objective that has been reached with more than 80 students involved in the project, most of the technological objectives of Delfi-n3Xt have also been fulfilled with successful in-orbit demonstrations of payloads and platform. Among these demonstrations, four are highlighted in this paper, including a solid cool gas micropropulsion system, a new type of solar cell, a more robust Command and Data Handling Subsystem (CDHS), and a highly integrated Attitude Determination and Control Subsystem (ADCS) that performs three-axis active control using reaction wheels. Through the development of Delfi-n3Xt, significant experiences and lessons have been learned, which motivated a further step towards DelFFi, the third Delfi CubeSat mission, to demonstrate autonomous formation flying using two CubeSats named Delta and Phi. A brief update of the DelFFi mission is also provided. [ABSTRACT FROM AUTHOR]

The aim of this paper is to identify the fatigue crack initiation and small crack growth mechanisms of GH4169 at 650 °C in air. Results show that fatigue cracks tend to initiate at oxidized inclusions. The crack incubation period takes up more than 90% of the fatigue lifetime. The δ phase can improve the crack initiation life and the total fatigue lifetime. The similarity between small crack and long crack growth data at relatively high Δ K can be attributed to the similarity of propagation mode. Two three-stage models are proposed to describe the cracks initiation and propagation processes. [ABSTRACT FROM AUTHOR]

The interactions between dust and plasma-facing material (PFM) relate to the lifetime of PFM and impurity production. Series results have been obtained theoretically and experimentally but more detailed studies are needed. In present research, we investigate the evolution of kinetic, potential and total energy of plasma-facing material (PFM) in order to understand the dust/PFM interaction process. Three typical impacting energy are selected, i.e., 1, 10 and 100 keV/dust for low-, high- and hyper-energy impacting cases. For low impacting energy, dust particles stick on PFM surface without damaging it. Two typical time points exist and the temperature of PFM grows all the time but PFM structure experience a modifying process. Under high energy case, three typical points appear. The temperature curve fluctuates in the whole interaction process which indicates there are dust/PFM and kinetic/potential energy exchanges. In the hyper-energy case in present simulation, the violence dust/PFM interactions cause sputtering and crater investigating on energy evolution curves. We further propose the statistics of energy distribution. Results show that about half of impacting energy consumes on heating plasma-facing material meanwhile the other half on PFM structure deformation. Only a small proportion becomes kinetic energy of interstitial or sputtering atoms. [ABSTRACT FROM AUTHOR]

[Display omitted] • The pH effect of adhesion force of benzene on graphene is quantitatively studied. • The edge effect of adhesion force is confirmed by experiment. • The potential function method is used to reveal the mechanism of pH effect. • The edge effect is explained by the vdW and electrostatic interaction. Graphene materials, as drug carriers, play an important role in the specific drug delivery system. The drug molecules with aromatic structures can be adsorbed on the surface of graphene in vitro through π-π stacking interaction and released directionally at the lesion under special temperature and pH-value environment. This paper proposes a new experimental method and theoretical model for the purpose to study the effect and mechanism of environmental pH and edge of graphene on the adsorption mechanical properties between graphene and benzene. The experimental results based on atomic force microscope show that the acidic environment is more conducive to the adsorption of benzene on the surface of graphene than the alkaline environment. The adsorption performance of benzene at the center of graphene is better than that at the edge. Moreover, based on experimental results, mechanisms of pH effect and edge effect are revealed by potential function theory. The pH effect is influenced by the change of electrostatic interaction in different pH environments. In addition, edge effect is mainly dominated by van der Waals interaction. This study solves the problem of specific influence mechanism of pH on π-π stacking interaction using mechanical means for the first time, and shows that graphene as a drug carrier has strong pH response characteristics and great application potential. [ABSTRACT FROM AUTHOR]

Battery capacity fade occurs when battery capacity, measured in Ampere-hours, degrades over the number of charge/discharge cycles. This is a comprehensive result of various factors, including irreversible electrochemical reactions that form a solid electrolyte interphase (SEI) in the negative electrode and oxidative reactions of the positive electrode. The degradation mechanism is further complicated by operational and environmental factors such as discharge rate, usage and storage temperature, as well as cell-level and battery pack-level variations carried over from the manufacturing processes. This research investigates a novel Bayesian method to model battery capacity fade over repetitive cycles by considering both within-battery and between-battery variations. Physics-based covariates are integrated with functional forms for modeling the capacity fade. A systematic approach based on covariate identification, model selection, and a strategy for prognostics data selection is presented. The proposed Bayesian method is capable of quantifying the uncertainties in predicting battery capacity/power fade and end-of-life cycles to failure distribution under various operating conditions. [ABSTRACT FROM AUTHOR]

The poisoning of Pt-based catalyst occurs generally during methanol electro-oxidation. Though traditional electrochemical techniques have probed these issues intensively, it is amazing to find that the negative resistance presents in the intermediate potential zone during an electrochemical impedance spectroscopy (EIS) measurement. Based on the chemical reaction analysis, we establish an EIS model and make some numerical analyses, thus determining the specific EIS shapes and equivalent circuits relating to various potential zones. These results not only compensate the drawback for traditional electrochemical approaches, but also reveal the dynamic adsorption of CO and OH species on Pt surfaces, providing a chance for understanding bifunctional mechanism towards quantitative manners. Significantly, we clarify that the negative resistance begins from the maximum catalysis of methanol electro-catalysis and ends in the initial passive state on Pt surfaces, offering a tool for further improvement. Interestingly, our discovery for negative resistance is consistent with that in general electrochemical system, facilitating its extension and direction in future. [ABSTRACT FROM AUTHOR]

The aim of this paper was to identify the grain size effect on the small fatigue crack initiation and growth mechanisms of nickel-based superalloy GH4169. Results showed that there was a transition of fatigue crack initiation mechanism between fine-grained material and coarse-grained material. Small fatigue crack growth rates were almost constant across a wide range of crack lengths. Once the surface crack length reached the critical size of 200 μm, the crack would propagate fairly quickly. At a given experimental condition, the scattering of fatigue lives of the parallel specimens was dependent on the crack initiation mechanisms. [ABSTRACT FROM AUTHOR]

Oil-related events have increased the uncertainty and complexity of the worldwide oil market. This paper investigates the effects of four types of oil-related events on world oil prices, using an event study methodology and an AR-GARCH model. The Internet information concerning these events, which is derived from search query volumes in Google, is introduced in an analytical framework to identify the magnitude and significance of the market response to oil-related events. The results indicate that world oil prices responding to different oil-related events display obvious differentiation. The cumulative abnormal returns, which reflect the influence of the global financial crisis, tend to drop first and then reverse and rise, while the cumulative abnormal returns induced by other oil-related events present a stronger persistent effect. The impact of the global financial crisis on oil price returns is significantly negative, while the impact of the Libyan war and hurricanes is significantly positive. However, the reactions of oil price returns to different OPEC production announcements are inconsistent. [ABSTRACT FROM AUTHOR]

Laminar forced convective heat transfer is studied for the purpose of getting the best heat transfer performance with the least flow resistance increase. The variation calculus method is employed to establish the equations describing the optimized fluid velocity field and temperature field. Numerical solutions of the equations for a convective heat transfer process in a section-cut of a square duct indicate the optimized flow should have a transverse secondary swirl flow pattern consisting of multiple vortexes with identical swirl direction in the junction region of any two neighboring vortexes. We then propose the convective heat transfer enhancement method relying on excitation of transverse secondary swirl flow. To validate this method, we numerically study the heat transfer and flow resistance characteristics of laminar flows in tubes with four-reverse-vortex-generator (FRVG) inserts, four-homodromous-vortex-generator (FHVG) inserts, or a twisted tape insert. The calculated transverse secondary flow in the tube with the FRVG inserts approximately follows the optimized flow pattern and the tube is thus found to have the best thermo-hydraulic performance, validating the proposed convective heat transfer enhancement method. [ABSTRACT FROM AUTHOR]

Underactuated attitude control is supposed to be used on spacecraft when failure happens with onboard actuators. One main problem with existing underactuated attitude control designs is their limited capabilities against disturbances. In order to solve this problem, an approach based on the theory of H ∞ is proposed in this paper. Two propositions are derived from the H ∞ theory to improve the robustness of one popular underactuated attitude control design, which was presented by Tsiotras et al. It is proved mathematically that the controller satisfying these two propositions respectively can stabilize the underactuated attitude system locally or globally. The numerical simulations show that the improved controllers based on the H ∞ theory could provide higher pointing accuracy for small satellites against disturbances. This validates the effectiveness of the proposed H ∞ based approach to improve existing underactuated attitude control designs. [ABSTRACT FROM AUTHOR]

As a typical semiconductor, ZnO is considered as a favorable photocatalyst due to its excellent photoelectrochemical properties. However, low response of visible light and the recombination of photoinduced carriers limits its application in photocatalysis. Herein, a novel, robust and recyclable heterogeneous photocatalyst based on flower-like Co doped ZnO microspheres was presented without changing the hierarchical morphology. The crystal structure, light absorption, and electrochemical performance were systematically investigated, and the response of Co doped ZnO to visible light significantly enhanced with the gap band reduced from 3.20 eV to 2.54 eV. Due to the transformation of Co2+ to Co3+, more oxygen vacancies were produced, with more photoinduced electrons transferring to Co3+ which would greatly inhibit the recombination of photoinduced electrons and holes and improve photocatalytic activity. 2-Mercaptobenzothiazole (MBT) which is considered as a long half-life intermediate of antibiotic medicine is chosen as a target. As a result, the 7% Co-ZnO photocatalyst exhibited excellent photocatalytic activity for the degradation of MBT with the rate constant of 0.1498 min−1 and removing ratio of 97.3% in 50 min. The formation of excess oxygen vacancies and the conversion between Co2+ to Co3+ were further identified by XPS analysis. This work provides new sights for doping transition metal with different chemical valence in semiconductors for producing oxygen vacancy and improving the photocatalytic efficiency. [Display omitted] • A novel and recyclable heterogeneous flower-like Co doped ZnO microspheres is prepared via simple procedure. • Doping of Co species effectively reduces the band gap energy of ZnO with the formation of abundant oxygen vacancies. • Electrons are trapped due to the transformation of Co2+ and Co3+ which hinders the recombination of photo-induced carriers. • The formation of oxygen vacancies and the conversion between Co2+ to Co3+ are further identified by XPS analysis. • The prepared photocatalyst exhibits excellent photocatalytic activity for degradation of 2-mercaptobenzothiazole. [ABSTRACT FROM AUTHOR]

Abstract: This paper attempts to characterize failure behaviour of small satellites through statistical analysis of actual in-orbit failures. A unique Small Satellite Anomalies Database comprising empirical failure data of 222 small satellites has been developed. A nonparametric analysis of the failure data has been implemented by means of a Kaplan–Meier estimation. An innovative modelling method, i.e. Bayesian theory in combination with Markov Chain Monte Carlo (MCMC) simulations, has been proposed to model the reliability of small satellites. An extensive parametric analysis using the Bayesian/MCMC method has been performed to fit a Weibull distribution to the data. The influence of several characteristics such as the design lifetime, mass, launch year, mission type and the type of satellite developers on the reliability has been analyzed. The results clearly show the infant mortality of small satellites. Compared with the classical maximum-likelihood estimation methods, the proposed Bayesian/MCMC method results in better fitting Weibull models and is especially suitable for reliability modelling where only very limited failures are observed. [Copyright &y& Elsevier]

Highlights: [•] The impact of market concern derived from the Web on oil volatility is analysed. [•] It has an equilibrium relationship between oil prices and long-run market concern. [•] The short-run market concerns have an asymmetric influence on oil price volatility. [•] The Internet can exaggerate the impact of information shocks on oil price. [ABSTRACT FROM AUTHOR]