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As a core component in high-pressure hydrogen storage systems for hydrogen fuel cell vehicles, the spring-loaded hydrogen decompression valve (SHDV) directly affects the performance of the hydrogen fuel cells. In this study, the transient flow characteristics of fluid– structure interaction in SHDV are investigated using the dynamic mesh method and real gas model. The complete closure of the valve spool is realized by the porous medium model. Adverse pressure gradients, flow separation, and unsteady vortex evolution in the decompression valve are numerically calculated with large eddy simulation, and the reliability of the calculation is verified by the experiments and theoretical model. Results show that the characteristic curve of the SHDV startup process can be divided into three phases: rapid response phase, closure phase, and equilibrium phase. The change in spool angle slightly affects the rapid response phase but substantially affects the fluctuations of pressure and flow during the closure and equilibrium phases. In the equilibrium phase, typical adverse pressure gradients and flow separation occur downstream of the spool, gradually propagating into the control chamber and causing pressure instability. Backflow under the large-angle spool is primarily caused by adverse pressure gradient and wall shear stresses, whereas backflow under the small-angle spool is mainly formed by the obstruction of the upper wall at the control chamber. By adding a convex cylinder structure to the spool, adverse pressure gradients and flow separation downstream of the large-angle spool can be effectively suppressed. [Display omitted] • The transient flow characteristics of fluid-structure interaction are investigated. • The complete closure of the spool is realized by the porous medium model. • The adverse pressure gradient and flow separation are investigated. • The evolution mechanisms of unstable vortices are clarified. • Optimization of unsteady flow downstream of the spool by convex cylinder. [ABSTRACT FROM AUTHOR]

Abstract: Kerogen was treated for 24h at temperatures of 250–700°C and pressures of 500–1500bar. Raman spectroscopic study of the run products documented systematic changes in both the first- and second-order spectral features with temperature and pressure. The micro-FTIR analysis of the kerogen treated showed that the presence of hydrogenated functional groups and importance of aromatic rings in the structures of the kerogen increased with temperature. An abrupt change in the chemical composition and structural state of the kerogen treated occurred at ∼500°C. [Copyright &y& Elsevier]

Abstract: The chemical composition of a barren biotite granite, a two-mica granite, and a rare metal-bearing pegmatite (the No. 3 vein in Keketuohai, Altay Mountains, northwest China), along with mineral separates of apatite and mica, were analyzed and compared in the present work. Bulk chemistries of biotite granite, two-mica granite, and pegmatite rim are consistent with fractional crystallization trend from granites toward pegmatite. Changes in pegmatite composition can be explained mainly by fractional crystallization of biotite. Rb–Sr isochrons yield 248.8±7.5Ma for the biotite granite, 247.8±6.3Ma for the two-mica granite, and 218.4±5.8Ma for the pegmatite rim. Similar geochemical characteristics, including initial ε Nd(T) values (ranging from −0.76 to −3.04) for apatites, similar initial ε Nd(T) values for whole-rock samples of studied granites and pegmatite (ranged from −1.40 to −3.21) and for biotites from granites (ranged from −2.75 to −3.15) suggest that these rocks were derived from a common magma source. Old continental crust may have played a significant role in magma generation. Based on these data, we interpret the evolution of the Keketuohai granite–pegmatite by magma differentiation from a common source. Biotite granite was the first to crystallize, followed by two-mica granites. The residual melt was probably stored in a granitic batholith. The pegmatite veins were injected ∼30M.y. later during another episodic tectono-magmatic event in the Altay Mountains. [Copyright &y& Elsevier]

People with diseases such as stroke, spinal cord injury, and trauma usually have paretic ankle involvement because of the plantar flexor and dorsiflexor muscle weakness. Individuals with paretic ankle normally have the drop-foot gait, which has the complications of foot-slap after heel contact and toe-drag during the swing phase of a gait cycle. This could cause slow walking speed, short step-length, high metabolic cost, and high risk of tripping. Ankle-foot orthotic intervention is mostly prescribed to treat paretic ankle impairments. In addition, ankle-foot orthoses (AFOs) have been developed to assist human walking, which can reduce the wearer's metabolic cost of walking. To date, three kinds of AFOs have been developed, including the passive AFOs, semi-active AFOs, and active AFOs. This paper provides a systematic review on these three types of AFOs, where the biomechanics of normal and pathological gaits of human, the design concepts of the AFOs, and motion data collection of the human-machine system in human trials are described. The limitations of the currently developed AFOs and future research and development directions of AFOs are discussed, which would provide useful information for researchers to develop suitable AFOs. [ABSTRACT FROM AUTHOR]

A vital component that is frequently employed in the industrial powder conveying sector is the fluidized bed. In the light of powder unloading with a fluidized bed as the research object, an orthogonal experiment with two factors and four levels was established for the structural parameters of the fluidized bed. In the case of different noise factors, 16 schemes are designed and all schemes via computational fluid dynamics numerical simulation. The Taguchi method and regression analysis are used to analyze the response. Finally, the accuracy of the optimization results is tested. The results show that gas velocity decreases sharply at the airway's entrance and, then, gas flows to the second half of the airway and velocity decreases steadily and uniformly. Airway arc length L exerts a greater effect on the signal-to-noise ratio (SNR) than airway height H. The parameter combination of 180 mm L and 17 mm H for obtaining the optimal velocity distribution uniformity is determined. The test results indicate that the overall fluidization effect of the fluidized bed with the optimal parameters is better. The linked research findings can be used as a guide when designing a fluidized bed system for transporting comparable powder. [ABSTRACT FROM AUTHOR]

Material properties of the components of magnetorheological (MR) fluids are critical to their control accuracy and service life. The aim of this study was to reveal the effects of temperature on the material properties of MR fluid components. In this paper, a detailed introduction to the components of MR fluids, including main performance indicators and commonly used materials, was presented at first. Then, theoretical analysis and experimental investigation were performed on the temperature-dependent material properties of MR fluid components. These material properties included the magnetization properties of the magnetic particle, as well as the shear viscosity and thermal expansion of the carrier fluid. Experimental results indicated that both the mass magnetization and coercivity of MR particles decreased as the temperature increased and the phenomenon was particularly obvious at high temperatures. Moreover, an increasing temperature could lead to a severe decrease of the shear viscosity and a relatively large thermal expansion of the carrier fluid. Research results from this study may serve to provide a theoretical and an experimental basis for the preparation of MR fluids with high thermal stability. [ABSTRACT FROM AUTHOR]

Abstract: The Wangfeng–Tianger–Saridala ore district consists of over 20 orebodies with total proven gold reserves exceeding 15 tonnes. The district is located on the EW-striking Tianger (Bingdaban) shear zone in west Tianshan Mountains, northwest China. The lensoid orebodies are distributed along the shear zone in a region about 25 km in length and 1 km in width. Enhanced fluid flow and fracturing controlled location and orientation of mineralized zones during deformation along narrow shear bands oriented oblique to the overall shear zone margins. Fabrics in fractures and strain shadow overgrowths generally plunge steeply, parallel to the lineation in the surrounding cataclasite matrix consisting of new grains of quartz and minor amounts of micas. Native gold occurs in mylonitized granites or mylonitized sulfide–mica–quartz veins. Gold grade is closely related with the occurrence of sulfide–quartz veins. Pyrite and pyrrhotite in gold-bearing sulfide–quartz veins contain inclusions of native gold. Chondrite-normalized rare earth element (REE) distribution patterns for pyrite from the orebodies show light REE enrichments and negative Eu anomalies. Relationships between gold contents and Th/U, Zr/Hf and (La/Yb) N values for pyrites imply that gold-rich pyrites are different from gold-poor pyrites, thus indicate that the pyrites in the orebodies have a different origin compared with those in wall rocks. A Rb–Sr isochron for the mylonitized Au-bearing quartz veins indicates an age of 224±14 Ma with an initial 87Sr/86Sr ratio of 0.7294±0.0089 (MSWD=1.1). This age is conformed by 40Ar/39Ar dating on muscovites (220.9 to 222.5 Ma), which is interpreted as the age of ore-formation in the Tianger deposit. High initial 87Sr/86Sr ratios (0.7294), high δ 34S values (+11.2 to +16.5‰), low δ 18OH2O values (1.67 to 3.07‰) and low δD values (−84 to −104‰) indicate that the ore-forming fluid was unrelated to any magmatic process. [Copyright &y& Elsevier]

The objective of this study is to demonstrate the basic characteristics of thermophilic strain TH-2 and evaluate the effect of strain TH-2 on different crude oils. Strain TH-2 is a non-motile, Gram-negative, oil-degrading thermophile that was isolated from a reservoir of the Shengli oil field in East China. The cells of strain TH-2 were grown at high temperatures up to 85 °C in the neutral to alkaline pH range. Depending on the culture conditions, the organisms occurred as single rods, or as filamentous aggregates. Strain TH-2 was grown chemoorganotrophically and produced volatile fatty acids and such surfactants as 1,2-benzenedicarboxylic acid-bis ester, dibutyl phthalate, and di-n-octyl phthalate. It could use different organic substrates (acetate, d-glucose, fructose, glycerol, maltose, pyruvate, starch, sucrose, and xylose). Laboratory studies have demonstrated that the strain affected different crude oils, converted and degraded various components and changed the physical and chemical properties of crude oils. The strain TH-2 degraded crude oil and growth of the bacterium on crude oil resulted in loss of aromatic hydrocarbons, resins, and asphaltenes. The bioconversion of crude oils leads to an enrichment in lighter hydrocarbons and an overall redistribution of these hydrocarbons. The interactions of microorganisms with crude oils are variable and depend on the microbial species and the chemical compositions of crude oils. Different interactions may influence the efficiency of processes in which single or mixed microbial species are used for the oil treatment and may also suggest possible combinations of biological and chemical technologies. [Copyright &y& Elsevier]

• A kinematic position decomposition strategy is proposed to assign different motion targets to the macro and micro arm respectively to reduce the dimension of the nonlinear kinematic problem. • An improved particle swarm (PSO) algorithm with a dynamic learning factor, called DFPSO, is proposed, which can accelerate and optimize the processing of solving nonlinear formulas of redundant robot's kinematics. • Use the potential energy calculated by the dynamic model as an optimization index to filter the redundant solutions by the DFPSO algorithm. The Chinese Fusion Engineering Testing Reactor (CFETR) is a superconducting Tokamak device, whose components would get gradually damaged by being susceptible to high temperature, strong magnetic field, radiation, and so on, and should be maintained regularly. The CFETR Multipurpose Overload Robot (CMOR) is a redundant robot designed as a macro-micro arm structure for a gigantic workspace in the blanket and diverter of CFETR's maintenance. Due to the macro-micro arm structure, the robot has a high degree of freedom, and its serial DOF is up to 16 so the traditional algorithm is low efficient for the robot's kinematics. Hence, in this paper, a kinematic decomposition strategy is proposed to allocate or decouple the position aim. Besides, a novel particle swarm optimization (PSO) with dynamic accuracy called dynamic factor particle swarm optimization (DFPSO) is designed to accelerate solving the high-dimensional nonlinear kinematic problem and to improve accuracy. The results of the research show the validation and efficiency of DFPSO in the CMOR system's kinematics. Moreover, it's also a universal kinematic algorithm for all high-DOF robots. [ABSTRACT FROM AUTHOR]

• An offline and online distributed architecture is proposed for fusion robots, which is more conducive to algorithm development and verification in fusion intelligent maintenance. • The use of an open-source platform is efficient for the rapid construction of the system software in the device development stage, has better economic benefits compared to commercial software, and is convenient for more researchers in develop projects collaboratively. • 3. The CMOR Motion Control System is a systematic solution from software to hardware control, which covers multiple scalable modules such as robot control, planning, simulation, and algorithms, and provides a framework not only for new fusion robots developing in the future but also for the integration of new devices. The CMOR Motion Control System is a multi-degree-of-freedom, long-beam, heavy-duty robot system with end effectors used to maintain the blanket and divertor of the China Fusion Engineering Test Reactor (CFETR) with irregular structural geometry. Since the multi-degree of freedom, large size, and flexible structure of the fusion robot will increase the complexity of the algorithm, it is necessary to design the corresponding control system and auxiliary algorithm to realize the motion control of the robot. In this paper, a feasible CMOR (CFETR Multipurpose Overload Robot) motion control system architecture is proposed, which adopts the distributed control structure of the upper and lower machine. Firstly, the game theory algorithm decouples the macro arm with 9-degree-freedom and the micro arm with 14 degree-of-freedom (dual 7-DOFs robots) and separates the pose and accuracy targets after planning the motion of the target task with the Markov chain. Secondly, to improve the accuracy, the kinematics controller based on macro arm motion planning strategy for initial positioning and the force-position hybrid controller based on micro arm motion planning strategy for compensation for precise positioning are designed separately. Finally, a robot distributed architecture is designed to realize offline and online simulation and control in which the offline mode simulates a collision-free trajectory based on the game theory and the online mode synchronously displays fusion robot motion by digital twin technology. The feasible CMOR motion control system architecture is proposed in this paper which can assist complex algorithms to achieve intelligent control in the fusion application. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: Water of high pressure and temperature is attracting attention for its unique properties and here an in situ observational technique has been developed to study organic matter transformations in H-P and -T (high-pressure and -temperature) water. Three samples of different kind involving aromatic organic compound, polymer, and natural biomass behave greatly different. Anthracene dissolves in water at the temperature of 325°C and corresponding pressure of 315.9MPa and remains stable till the highest temperature of 420°C of this work. Polystyrene and rice straw hydrolyze in the form of heterogeneous phases in H-P and -T water. Polystyrene melts to form non-soluble liquid spherule before hydrolysis, whereas rice straw hydrolyzes directly from non-soluble solid. The light organic molecules produced from hydrolysis dissolve in water at high temperatures and separate out during cooling. The study is helpful to understand reaction mechanism and process of hydrolysis of biomass and polymer in H-P and -T water. [Copyright &y& Elsevier]

Mixtures of CO2-NaCl-H2O contained in synthetic fluid inclusions are studied by laser Raman spectroscopy at high temperatures. With increasing temperature, the band splitting (X) of υ1-2υ2 diad of spectrum of CO2 presents more variations, and the intensity ratios of the hot bands to the υ1-2υ2 diad increase. For mixtures of gas phase rich in CO2 and liquid phase rich in H2O before homogenization, the strength of hydrogen bonding of water in the liquid phase decreases almost linearly with increasing temperature. When mixtures become homogeneous liquid phases, carbon dioxide content increases significantly as a result of the abrupt decrease in hydrogen bonds. Our results show that the hydrogen bonds change only slightly at higher temperatures above the homogeneous point, and a certain extent of the hydrogen bonds still remains at the highest temperature of 550°C of this work. The study is helpful to Raman spectroscopic analysis of natural fluid inclusions at high temperatures. [Copyright &y& Elsevier]

The raft-type wave energy converter (WEC), consisting of several hinged rafts and hydraulic power take-off (PTO) systems, captures wave power in a line absorber manner, whose scattered and radiated wave pattern is different from that of a point absorber. This paper focuses on the latching control of a raft-type WEC consisting of two rafts and a hydraulic PTO system. To reduce the complexity of finding the optimal latching duration, the hydraulic PTO system is modelled as a Coulomb damping and the optimal latching control law is derived from a Coulomb damping-based model using the optimal control theory. The effectiveness of latching control on improving power capture ability of the raft-type WEC with a hydraulic PTO system and the benefit introduced by latching control in terms of power improvement are investigated. Results show that the optimal latching control law derived from the Coulomb damping-based model can effectively improve the power capture ability of the raft-type WEC with a hydraulic PTO system. The benefit due to latching control can reach a peak value of 3.04, which is 2 times that introduced by load control. Moreover, latching control can further benefit the raft-type WEC where load control has been performed. • Coulomb damping characteristics of the hydraulic PTO system is considered. • Determination of the optimal latching duration is specified and studied. • Effectiveness of latching control on a raft-type WEC with a hydraulic PTO is studied. • Benefit due to latching control in terms of power improvement is investigated. • Latching control can further benefit the raft-type WEC where load control has been performed. [ABSTRACT FROM AUTHOR]

To accurately describe the power transmission in the hydraulic power take-off (HPTO) system, a high-precise model for the HPTO system of a raft-type wave energy converter is presented. The model incorporates all the necessary dynamics and the undesirable physical effects, such as pressure drop, flowrate leakage, flow resistance, and friction. The model is validated by the comparison with the results obtained using a hardware-in-the-loop test rig and results show that the proposed model can describe the power transmission more accurately than previous models. Furthermore, the research focuses on the holistic performance of the HPTO system including the transmission efficiencies of HPTO components, the overall transmission efficiency of HPTO system and the power losses of HPTO components across a wide range of wave parameters. Results show that the power losses from each component and the efficiencies of the hydraulic cylinder and the generator increase as wave height increases or raft length-to-wavelength ratio approaches the optimal value, while the efficiencies of the check valves and the pipeline display inverse variation tendencies. Besides, the hydraulic motor is the main contributor to the overall power losses and the HPTO efficiency displays a similar variation tendency against wave parameters with that of the hydraulic motor. • A high-fidelity model for the HPTO system of a raft-type WEC is proposed. • The model incorporates all the relevant dynamics and undesirable physical effects. • Impact of undesirable physical effects on power capture and generation is analyzed. • Power losses and efficiencies of HPTO components are investigated. • Hydraulic motor is the main contributor to the overall power losses. [ABSTRACT FROM AUTHOR]

Shock tunnel tests and CFD simulations are conducted to study effects of vortex generators (VGs) on unsteady unstarted flows of an axisymmetric hypersonic inlet with nose blunt radii of 0.8 mm and 3.2 mm. The inlet exit is throttled with a preseted block to generate unstarted flows at a freestream Mach number of 5.9. Unstarted flows of no VGs, 0.5 mm and 1 mm-thick VGs are recorded through schlieren imaging and pressure measurements. Experimental results show that the unstarted flows are characterized with prominent shock oscillations and pressure fluctuations. VGs reduce scales of the external separations, enlarge angles of the separated shock waves, and increase time-averaged magnitudes of surface pressures. The oscillatory period can be shortened from 4 ms to 3.13 ms by 1 mm-thick VGs for the R 0.8 mm configuration. The maximum increment of the time-averaged pressure magnitudes can reach 16.2 times the freestream static pressure (p ∞) for the R 0.8 mm configuration with 1 mm-thick VGs. In addition, VGs generally increase pressure standard deviations of the measuring points upstream of the throat section within 4.0 p ∞ and decrease those of the downstream measuring points up to 8.6 p ∞ , despite the 0.5 mm-thick VGs condition of the R 3.2 mm configuration. Flow mechanisms dominating the effects of VGs on the unsteady unstarted flows are analyzed with the aid of the CFD simulations. Feasibility of VGs on unstarted flow control is also evaluated. [ABSTRACT FROM AUTHOR]