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This study introduces the low‐volume core (LVC) fabrication method, which enables the monolithic molding of compact, complex, versatile, and intelligent soft robotic systems. This method uses thin and flexible thermoplastic sheets to mold internal chambers in soft fluidic actuators, valves, and circuits. The LVC fabrication method creates low‐volume networks in soft actuators (LV‐net actuators) that can be made with compact and complex geometries, enabling both low actuation volume input and multi‐degree‐of‐freedom actuators. LVC fabrication can also be used for compact, completely soft, and monolithic logic components (valves with low‐volume core, also called as LV valves) to provide directional resistance as well as a switching mechanism that enables fluidic logic in soft systems. The compatibility of the fabrication methods for both soft actuators and valves facilitates the creation of compact, integrated, and versatile soft robotic systems with embodied intelligence. This study introduces two examples of such intelligent soft robotic systems that integrate both LV‐net actuators and LV valves to demonstrate capability for complex system fabrication. [ABSTRACT FROM AUTHOR]

The geometrical measurement precision of laser spots is affected by the deviation between the parameters of the laser altimeter and the laboratory measurement results, and the inversion accuracy of surface object height is also limited. The measurement parameters and the load state can be obtained by calibration of the laser altimeter system. Usually, ground detectors are deployed to calibrate the measurement parameters of the laser altimeter, including the divergence angle and the energy distribution of the laser beam. A calibration method for a laser footprint spot without a calibration field was proposed in this paper, focused on the airborne large-footprint laser altimeter system. The geometric parameters of the laser spot were calibrated through the laser echo waveforms of a specific terrain. The experimental results show that geometric calibration of the large-footprint laser altimeter can be achieved in the area of the step surface. The divergence angle of the laser beams obtained from the six experimental areas is 4.604 ± 0.359 mRad, and the consistency of the energy distribution from each laser spot reaches 92.67%. A new method of on-orbit calibration and verification is provided for the satellite laser altimeter system. [ABSTRACT FROM AUTHOR]

• An experimental analysis was present for SGTR in LFRs. • An equation and a dimensionless number were put forward for maximum pressure peak. • Dynamic pressure attenuation was matched based on steam cavity pulse theory. • Reasonability of applying two-phase critical model in SGTR study was demonstrated. Steam Generator Tube Rupture accident (SGTR) accident is one of the main safety events to the industrial application of Lead-cooled Fast Reactors (LFRs). This paper presents a separate effect test facility, called Lead-bismuth Eutectic Steam generator tube rupture Test facility (LEST), for testing high-pressure subcooled water jetting into a Lead Bismuth Eutectic (LBE) pool, and analyzes experimental data of maximum initial pressure peak, dynamic pressure attenuation together with the pressure rising process upon SGTR. The experimental analyses put forward a general equation form together with a dimensionless number of the initial pressure peak associated with a high-pressure Newtonian fluid injecting into another low-pressure Newtonian fluid, and the derivation of the general equation form is specifically applied to match a further semi-empirical equation for an initial maximum pressure peak with 5–10 MPa water injection in SGTR. The attenuation curve of dynamic pressure wave in each experiment is matched, and more weakening conditions can change the pressure peak from concentrated and non-period peak group to approximate period 1.4–3.7 s pulse group. The size relationship between pipe length L and nozzle diameter D , which L / D = 12 , is set to divide SGTR into small wall rupture and tube shear fracture, further three stages of pressure rising are distinguished in the tube shear fracture. This work provides experimental data to help determining the severity of SGTR and assessing the consequences of this event as part of the safety case for the industrial application of LFRs. [ABSTRACT FROM AUTHOR]

Numerical simulation analyses of LIFUS5/MOD2 experiment facility for hyperbaric steam-water jet inside liquid lead bismuth eutectic (LBE) were conducted using computational fluid dynamics (CFD). Alchagirov surface tension correlation and Lee evaporation model were applied in Eulerian-Eulerian two-phase flow model. Benchmark study was performed by comparing the CFD results against experimental data. Four thermal-hydraulics phenomena of sensitivity analysis were established under three extended conditions. These include 1) argon zone compression risk, 2) pressure rising and initial pressure peak, 3) argon entrained by LBE fluctuation, and 4) LBE level rising and steam cavity diffusion path. Overall, CFD models have a great advantage simulating pressure change and pressure wave transfer with 0.37% maximum error. LBE level rising and the radial and even diffusion of steam cavity should happen simultaneously under steam generator tube rupture accident (SGTR). This study provides the engineering basis for Lead-cooled Fast Reactor (LFR) design to improve its safety margin. [ABSTRACT FROM AUTHOR]

• Heat transfer experiment of hydrogen with variable property was conducted in a heated tube. • New friction and heat transfer correlations were developed with a satisfactory accuracy. • Acceleration parameter was used to modify the heat transfer correlation in a wide range. Hydrogen as a fuel or a coolant plays an essential role in carbon emission reduction and energy system transformation. There has been a long need for a better method of explaining the heat transfer mechanism for gases with variable physical properties in the past few decades. In this study, an experimental investigation was conducted to explore the heat transfer and flow friction of hydrogen in a horizontally heated tube for the following ranges: local Reynolds number from 4300 to 48600, local wall temperature up to 1200 K, local wall-to-bulk temperature ratio up to 2.37, and heat flux up to 0.57 MW/m2. The average friction coefficient equations with heat addition are developed for 6000 < Re < 105 and 1.20 < T w / T b < 1.85. It is found that the modified average heat transfer correlation by the acceleration parameter K v is proposed for 4900 < Re < 44500 and 5 × 10−8 < K v < 1 × 10−6 that can cover the laminar-turbulent transition and turbulence regime with an accuracy of ±10%. A new correlation evaluated at the bulk temperatures is proposed with the temperature and length correction to predict the local heat transfer of hydrogen, which is in good agreement with the experimental data in the range of 8000 < Re < 48000, 6.2 < x / D < 111, and 1.17 < T w / T b < 2.37. This investigation can facilitate improvements in thermal hydraulics analysis codes and the heat transport system with variable fluid properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • Thermal conductivity of hybrid nanofluids was greatly improved. • Functionalization of h-BN contributes to the favorable dispersion behavior. • Thermal conducting pathways appeared in the hybrid nanofluids system. • The composite process further facilitates thermal performance enhancement. This study mainly investigated the physicochemical characteristics of ethylene glycol/ water (EG/W) based hydroxyl-functionalized boron nitride (BN-OH) and graphite (G) hybrid nanofluids. A novel simple and efficient annealing method was proposed to have hexagonal boron nitride (h-BN) nanoparticles functionalized to improve the synergistic role between hybrid G/BN-OH nanoparticles. Meanwhile, the dispersion stability, thermal stability, and rheological behavior of diverse nanofluids (h-BN, BN-OH, G, G/BN and G/BH-OH) were comprehensively evaluated. The results showed that the G/BN-OH hybrid nanofluids demonstrate both better dispersion stability and thermal stability, as well as a lower increase in viscosity. In addition, the thermal conductivity of G/BN-OH hybrid nanofluids was increased by up to 18.05% with a concentration of 0.2 wt% when compared to the base fluid. Ultimately, the complicated theoretical mechanism of thermophysical performance augment for G/BH-OH hybrid nanofluids was reliably presented. The enhanced thermal conductivity of nanofluids may be attributed to the formation of adsorption layers and the synergistic effect of the thermal conductivity network. [ABSTRACT FROM AUTHOR]

• LEST was built to study transient SGTR multiphase accident of LFRs. • Initial pressure peak wave was firstly captured as a potential threat to reactor. • Pressure wave transmission and attenuation was fitted. • Three-dimensional plot of steam cavity transport was shown. Transient multiphase flow phenomenon of hyperbaric water jetting into lead-based eutectic (LBE) is of significant importance for safety analysis of Lead-cooled Fast Reactors (LFRs). In order to investigate the thermal-hydraulic parameters under Steam Generator Tube Rupture (SGTR) Accident in LFRs, the Lead-bismuth Eutectic Steam generator tube rupture Test facility (LEST) was built and the effects of (1) initial pressure peak, (2) pressure rising, (3) steam cavity migration in reaction vessel were evaluated. Under the present experimental and theoretical analysis, the results showed that the maximum pressure peak of 2.93 MPa occurred under the condition of 10 MPa water initial pressure which is the highest experimental requirements of reactor second system, and the accident consequence of pressure peak together with the maximum rising rate 2.001 MPa/s might be the most serious. Floating rate of steam cavity was different in radial direction, and was affected by water pressure and LBE level height. The analysis results will provide severity assessment for safety design, accident forecasting and engineering guidance of LFRs. [ABSTRACT FROM AUTHOR]

Lead-cooled Fast Reactors (LFRs) has become a main candidate choice among the fourth-generation reactors, and Steam Generator Tube Rupture accident (SGTR) is one kind of its important Design Extension Condition (DEC). Due to the limitations of existing theoretical research and simulation tools, many SGTR thermal-hydraulic experiments have been carried out recently. This paper reviews thermal-hydraulics stages into four stages: 1) water-LBE interaction together with steam explosion, 2) high-pressure water jet and structures impact, 3) steam bubbles transport in primary system, 4) bubble entrained and stayed in the reactor core. The existing SGTR experiments are classified as separate SGTR effect test experimental facilities and separate LBE-water interaction experimental facilities. The methods of high-pressure injection, LBE status change and parameters measurement of separate SGTR effect experimental facilities are introduced. Four experimental prospects for further research are suggested as pressure transmission and structure impact, steam lifting and visualization, bubble transport in full-scale or reduced-scale model of reactor, behaviors of LBE-water mixture. • An LFR experimental review of SGTR thermal-hydraulic experiments. • SGTR thermal hydraulic phenomena are divided. • SGTR thermal hydraulic experiments are classified into two categories. • Experimental methods introduction and further research suggestion. [ABSTRACT FROM AUTHOR]

In order to meet the personalized needs of Chinese intelligent vehicles and improve the satisfaction and acceptance of human–computer interaction and collaboration in domestic intelligent vehicles. In this paper, we design an adaptive longitudinal following model that integrates the perceptual perturbation process and driver characteristics for simulating driver following behavior and studying the variability of driver following behavior. Firstly, for the independence and randomness of driver perception process, a set of random variables conforming to Wiener process is introduced to simulate the perception process of speed and following distance of the vehicle in front; secondly, for the characteristic differences of different drivers' following behavior, a driver characteristic parameter identification algorithm is designed to identify the expected collision time distance and following distance parameters of different drivers, and the identified parameters will be used for Again, a sliding mode control system based on fuzzy switching gain adjustment is designed to simulate the driver following control system. The results show that the designed following model recognizes the driver's characteristics well and can better simulate the driver's following behavior, and the following index is relatively improved by 80%. [ABSTRACT FROM AUTHOR]

• A DPM Model with a drag coefficient correlation is performed to simulate SGTR. • The possibility and location of bubbles entrained to the core are evaluated. • The effects of rupture height, rupture periphery and bubble size are analyzed. • Two experiments about ratio of bubbles amount are considered in the simulation. Steam generator tube rupture (SGTR) is a design basis accident in Lead-cooled Fast Reactor (LFR). A 1/8 centrosymmetric scale geometric model of ELSY primary system is adopted to build the computational domain. A Eulerian-Lagrangian CFD Discrete Phase Model (DPM) with an appropriate drag coefficient correlation is performed, and a base case of bubble transport study is analyzed to obtain the distribution of bubbles. Furthermore, the possibility of bubbles entrained to the core is evaluated. Results show that bubbles firstly reach the core edge channels and then to the middle channels. Meanwhile, a rupture at low and peripheral position can inject more bubbles to the core. In addition, 0.3 mm-0.6 mm and 1 mm bubbles have the largest probability to reach the core, considering the amount of bubbles with different sizes. This study is a guiding paper for bubble transport in SGTR, and it can provide useful reference for judging the impact of accident. [ABSTRACT FROM AUTHOR]

The improved low temperature SCR activity and operating window of MnTiS0.05 caused by the greatly enhanced L-H route owing to the replacement of Ti4+ by S4+ to form Ti O S band. • S is doped into TiO 2 via the replacement of Ti4+ by S4+ to form Ti O S bond. • Brønsted acid sites and redox property are enhanced due to more active species. • Reactivity and amount of ad-NH 3 and ad-NO x species are improved. • L-H route occurred on the S-doped catalyst is more significant than E-R route. • MnTiS0.05 exhibits the best SCR performance and widest operating window. A series of S-doped MnO x /TiO 2 catalysts were prepared by sol-gel method for the purpose of enhancing SCR performance. The obtained catalyst with mole ratio of S:Ti = 0.05:1 exhibited the best low temperature SCR performance and the widest active temperature window. According to the results of various analyses, the proper S was doped into TiO 2 lattice via the replacement of Ti4+ by S4+ to generate Ti O S bond, along with increasing surface area, more surface Mn4+ species and more active oxygen species (O 2 −). These enhanced properties improved the Brønsted acid sites and redox property of the properly S-doped MnO x /TiO 2 catalyst. These advantages of S doping can essentially benefit the de-NO x ability of MnO x /TiO 2 catalysts. Meanwhile, the in situ DRIFT experiments revealed that the adsorbed NH 4 + and gas-phase NO 2 species were greatly increased after proper S-doping, along with the enhanced reactivity of the adsorbed NH 3 and NO x species. Both E-R and L-H mechanisms occurred on the S-doped catalysts, while the promoting effect of S-doping was performed by facilitating the L-H route during SCR reaction. [ABSTRACT FROM AUTHOR]

This study comprehensively investigated physicochemical and tribological performance of polyalphaolefin (PAO4) oil introducing oleic acid (OA)-functionalized SiC/TiN hybrid nanomaterials. The dispersion stability, wettability, thermal stability, and friction properties of the nanolubricants (NL) system were greatly improved following the application of hybrid NL. Additionally, the anti-wear and reducing-friction behavior were assessed via a four-ball tribometer. The results showed that the COF and WSD values of wear scar lubricated by hybrid NL were greatly reduced by approximately 32.7% and 35.1%, respectively, compared with the base oil. Finally, it is strongly confirmed that the significant improvement of friction performance is mainly due to improved interfacial effect of NL, the stable chemical tribo-film generated onto the friction surface, and the synergistic effect among SiC, TiN nanoparticles, and OA surfactant. • The synergetic role between hybrid nanomaterials and OA was proposed. • Dispersion stability and physicochemical performance of hybrid NL was further improved. • COF and WSD values were greatly reduced by approximately 32.7% and 35.1%. • The chemical tribo-film is responsible for the improvement of tribological performance. [ABSTRACT FROM AUTHOR]

The discrete element method (DEM) was applied to simulate the direct shear tests of irregular ballast stones by constructing clump particles, where irregular clumped-particles have similar particle size distribution (PSD) with those of the real ballast stone. With these clumped particles, the interlock of ballast stones in the direct shear test is investigated. The nonlinear contact force model with Mohr–Coulomb is adopted to model the interaction of the clumped particles. With different normal loads, the simulated microscopic characteristics in the direct shear test were linked with that of tests. The results demonstrate that DEM numerical simulations can produce interrelated responses of the ballast behavior, including the critical state response and are in good agreement with experimental observations. The shear resistance value increases with the normal stress application, indicating that the lateral confinement of ballast bed leading to less vertical settlement and more track stability. In addition, the DEM can further provide details of the microstructure evolutions during shearing processes. [ABSTRACT FROM AUTHOR]

Due to the difference in surface reflectivity, the laser measurement waveform data recorded in full waveform have a saturation phenomenon. When the signal is saturated, the echo waveform produces peak clipping and pulse spreading, which seriously restrict the accuracy of laser measurement results and the usability of data. Therefore, we conducted a ranging investigation on the "peak clipping" phenomenon of the saturated waveform and found a nonlinear time delay in the range, which is between the two extreme cases of saturated "dead time" and Gaussian fitting peak time as pulse signal reception time. Subsequently, based on the consistent relationship between the geometric characteristics of the high- and low-gain channels of the space-borne laser altimeter, we constructed a laser waveform saturation compensation model, namely, the laser pulse flight time delay compensation and the laser waveform peak intensity compensation, and carried out the data saturation compensation and validation with the dual-channel measurement data from the GaoFen-7 (GF-7) satellite. The experimental results showed that the saturation compensation model (SCM) proposed in this paper could restore the features of the saturated waveform signal and effectively improve the accuracy of the laser ranging. The accuracy of the laser waveform fitting result after saturation compensation improved from 0.7 ns (0.11 m) to 0.14 ns (0.02 m), which greatly improved the usability of the saturated laser measurement waveform data. [ABSTRACT FROM AUTHOR]

The freshwater red-eared slider (Trachemys scripta elegans) is found not only in freshwater but also in coastal saline habitats. Hyperosmotic salinity can induce cell damage. p53, regarded as the guardian of the genome, is very important and versatile in response to the change of environment. In this study, the role of p53 in T. s. elegans under environmental salinity change will be explored. The results indicated that amino acid sequence of p53 showed high similarity to p53 of other species. In addition, the expression of p53 showed differences in various tissues under normal condition. Under salinity stress, the mRNA levels of p53 in the liver increased significantly at 48 h with 15‰ group (15 practical salinity units-exposed group). In the heart, p53 mRNA levels increased at 6 h in 5‰ (5 practical salinity units) and 15‰ groups. Furthermore, the changes of p21 mRNA expression levels in liver and heart were similar to p53, while cyclin D1, cyclin-dependent kinase4 (CDK4) and cyclin-dependent kinase6 (CDK6) showed opposite changes to p53. Moreover, Bax and caspase 3 mRNA expression levels were similar to p53, respectively, while Bcl-2 showed opposite changes. The positive cells of apoptosis were found in the liver of 15‰ at 48 h and 30 d of chronic stress. Taken together, these results indicated that the T. s. elegans may protect itself by regulating cell cycle progression and apoptosis of damaged cells under salinity stress, which played an important role for T. s. elegans in salinity adaptation. The invasive species Trachemys scripta elegans , a freshwater turtle, activated p53 signaling to protect itself by inducing apoptosis of damaged cells through Bax-caspase 3 pathway, or contribute to the self-repair of damaged cells by regulating cell cycle progression through the cyclin D1-CDK4/6 pathway, in response to elevated environmental salinity. Unlabelled Image • CDS region of p53 gene in Trachemys scripta elegan was contrastively analyzed with other species. • Under salinity stress, hepatic p53 expression decreased firstly and then increased. • p53 modulates cell cycle by p21, cyclin D1 and CDK4/6 and regulates apoptosis by Bax, Bcl-2 and caspase 3 in Trachemys scripta elegan in response to salinity stress. [ABSTRACT FROM AUTHOR]

• The thermal–hydraulic characteristics of lead–bismuth eutectic in a vertical tube under rolling conditions are numerically investigated. • It is concluded that the frictional resistance coefficient and heat transfer correlations now used are not suitable for the ship-based LFR. • Comparison with water coolant shows that the enhancement of radial secondary flow is the main cause for the change of heat transfer ability of coolant. The investigation of flow and heat transfer of lead–bismuth eutectic (LBE) under rolling conditions is vital to the application of LBE cooled reactor in offshore engineering. In this paper, mature numerical method for modelling low Prandtl number liquid metal is used for LBE flow in a vertical tube under rolling conditions. Reynolds stress turbulent model is chosen to consider the complex secondary flow caused by additional force. It is found that the transverse additional force is the main reason accounting for the enhancement of heat transfer and secondary flow. The transient maximum heat transfer ability can be enlarged by 18% under condition of rolling angle of 30° and period of 8 s. And 10 times transverse additional force caused by rolling angle of 30° and period of 8 s is enough to change the flow resistance characteristic of LBE. Comparisons with water coolant indicate that the intensity of radial secondary flow play an important role in determining the heat transfer characteristic of fluid under rolling conditions. The high density and low Prandtl number also make the features of LBE under rolling conditions different from those of water. The empirical correlations used in system code now could not predict the flow and heat transfer of LBE under rolling conditions. Special attention should be paid to safety design criteria of the off-shore LBE cooled reactor. This paper may contribute to the thermal–hydraulic design of off-shore liquid metal cooled reactors. [ABSTRACT FROM AUTHOR]

• A 2-D multiphase fluid dynamics code ACENA has been preliminarily developed. • This code is intended to simulate multiphase flow during LFR postulated accidents. • The models adopted in this code has been validated against several experiments. • The prediction results of this code agree well with experimental results. To simulate the heavy liquid metal-gas (HLM-gas) two phase flow phenomena that may occur during postulated accidents of Lead-based fast reactors (LFRs), a 2D multiphase fluid dynamics code, ACENA, is preliminarily developed and validated in this study. A brief description of theoretical models, including governing equations, auxiliary models and material properties are listed in this study. The capability of simulating flow and heat transfer characteristics between gas and liquid phases has been examined by typical air-water bubble column experiment, LBE-N 2 two phase flow experiment and Lead-Ar heat transfer experiment, and the comparison results show that this code could attain acceptable accuracy in simulating flow and heat transfer characteristics of HLM-gas two phase flow with appropriate interfacial drag coefficient and heat transfer coefficient models. [ABSTRACT FROM AUTHOR]