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Operation parameters restrict the performance of hydrocyclone in offshore platforms. Based on the computational fluid dynamics (CFD) software Fluent and the similarity parameter criterion experiment, the numerical simulation of the separation flow field and separation efficiency of hydrocyclone at different feed solid concentration was carried out, taking short circuit flow into account, a new correcting separation size equation was derived according to the locus of zero vertical velocity (LZVV) method. The results shown that when the feed solid concentration was more than 40%, the peak value of tangential velocity decreased and the increasing amplitude of underflow pressure drop will decrease compared with the increasing amplitude of overflow pressure drop, the region with the highest turbulence intensity increased when the concentration was more than 40%. The total separation efficiency and the feed solid concentration showed a positive correlation at 0 ~ 40%, and the increase in total separation efficiency was the smallest when it was higher than 40%, with a value of 0.63%. There was a large difference between the values of d50c* and d50c while the feed solid concentration was 50%. From the above results, it could be concluded that the optimum feed solid concentration ranges were 0 ~ 40%. The new correcting separation size equation could be used in the range of 0 ~ 40%. This study could have certain guiding significance for the field application of the offshore platform desanding hydrocyclone.

In order to study the internal flow field and oil-water separation mechanism of double cone hydrocyclone, based on fluid dynamics software Fluent, the effects of oil phase volume distribution, tangential velocity distribution, feed flow rate at different oil droplet sizes and fractional ratio at different oil concentration on the separation efficiency of the hydrocyclone were analyzed. The results show that the feed flow rate should be less than or equal to 3.5 m3/h to reduce the energy loss; The separation efficiency is the best when the oil droplet size is 1 mm–1.5 mm and the feed flow rate is in the range of 2.5 m3/h–3.5 m3/h; In order to achieve the highest separation efficiency, the split ratio should be 1.2–1.3 times of the inlet oil concentration. The research can provide reference for the separation mechanism and flow field characteristics of hydrocyclone.

Existing design equations can hardly provide reliable guidance in hydrocyclone designs and give explanations for the selected optimum range of spiral tube inlet. In this paper, the spiral tube inlet hydrocyclone for offshore oil-water separation was optimized by using the response surface method and multi-objective optimization method. With optimization results which were verified by numerical simulation and experiments discussed and analyzed, the optimal entrance structural parameters were obtained: d = 7.45 mm; D = 32.50 mm; h = 7.80 mm; C = 2.00, and the separation efficiency of the optimized hydrocyclone was increased by 8.34% and Euler number reduces 4.12. The optimization process show that the response surface method is reliable for the optimization of the inlet structure of the spiral tube, which provides technical guidance for the development and optimization of the sea oil produced water treatment equipment.

In order to reduce the fine particles in the underflow when the hydrocyclone is used to treat coalbed gas fracturing Flow-back fluids, a V-shaped outlet hydrocyclone was designed. Internal flow field of two hydrocyclones was simulated by RSM (Reynolds stress model) and Mixture model. The study shows that the V-shape outlet hydrocyclone can reduce concentration of the underflow particles with a diameter of 2.5 μm to 4.1%, which is 5.29 times lower than that of the ordinary hydrocyclone, and the particle concentration of 10 μm is reduced by 55.17%. In the internal flow field, the maximum pressure value of the V-shaped outlet hydrocyclone is 59.61% lower than that of the ordinary one. Compared with the ordinary hydrocyclone, the maximum negative pressure of V-shaped outlet hydrocyclone is reduced by a factor of 2.1. The maximum value of the tangential velocity in the semi-freedom vortex zone at the V-shaped outlet is 28.32% lower than that of the ordinary structure; the maximum of the axial velocity in the forced vortex zone is 40.03% higher than that of the ordinary one; the radial velocity of the V-shaped structure is reduced by 1.5 times as compared with the ordinary structure.

Inspired by the mechanisms of some insects which are capable of climbing and moving freely on various vertical rough surfaces with their claws and accessory components, we presented a new design of a flexible spiny structure called DNspine (a spine with double needles) featuring two anchoring points to enhance the mobility of wall-climbing robots (WCR). Each flexible spine consists of two separate suspension systems so that the near subspines in the flexible spiny structure will not interface with each other. The two-anchoring point design increases the contact area of spiny array to achieve a better attachment for WCRs. The single DNspine and its array were fabricated via fast prototyping. A customized setup using displacement-control method was carried out to characterize the contact performance of the single DNspine as well as its DNspine array. Their adhesion forces were measured on a sandpaper surface. The results show that both the DNspine and the DNspine array are able to increase the spine adhesion significantly compared with a single flexible spine and its array with only one anchoring point on rough surfaces.

A large amount of uranium-containing wastewater is produced by the nuclear industry, which causes harm to human health and the environment. Goethite (α-FeOOH) is highly insoluble in water and has a net positive surface charge, making it an effective sorbent for metal–anion complexes in aqueous solutions. In this study, goethite (α-FeOOH) and Fe2+-modified magnetic goethite (M-α-FeOOH) were prepared using an easy one-pot chemical precipitation method and used to remove uranium from solution. The adsorbents were characterized using scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), BET surface area analysis, fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and vibrating sample magnetometry (VSM). When Fe2+ partially substitutes for Fe3+, the material is magnetic, has a larger specific surface area and can be rapidly separated in a magnetic field. The uranium adsorption performance of M-α-FeOOH was substantially better than that of α-FeOOH, and its maximum adsorption capacity increased by 46.09%. The data fitted well with the quasi-second order kinetic model and the Langmuir isothermal adsorption model. According to the results of this study, the increase in the uranium removal performance of M-α-FeOOH was attributed to its higher specific surface area, better dispersion, and larger quantity of activated adsorption sites. These results, along with its low-cost, environmentally friendly, and facile synthesis, reveal M-α-FeOOH is a promising material for uranium capture.

In order to study the effect of limestone powder as an auxiliary cementing material replacing part of cement on the properties and pore structure of cement mortar, the working performance, mechanical properties and pore structure characteristics of cement mortar with 0%, 10%, 20% and 40% substitutions of limestone powder were tested. The experimental results show that with the increase of the amount of limestone powder, the fluidity of mortar increases continuously and the water retention also becomes better. The addition of limestone powder improves the workability of mortar, but with the increase of limestone powder, the compressive strength of mortar decreases continuously. The results of low field NMR show that the porosity of cement mortar increases firstly and then decreases with the increase of limestone powder content. Compared with the reference mortar, its porosity is improved to some extent, however the pore throat distribution indicates that the increase of porosity is caused by the increase of small pores between 0.01μm and 0.16μm. The harmful macropores between 0.16μm and 0.63μm in mortar are reduced, which indicate that the addition of limestone powder can effectively improve the pore diameter distribution of mortar.

This paper presents a three-row opposed gripping mechanism with radial configuration for wall-climbing robots inspired by the structure of the gripper of LEMUR IIB. The mechanism builds upon a kind of microspines for climbing robots. This work utilizes an opposed spoke configuration with 3 rows of 31 microspines on each linkage array, splayed around a central bracket. A single motor drives the 3 linkage arrays by a set of gears to achieve attachment and detachment procedures, and the trajectory of each linkage array tip makes the miniature spines easy to penetrate in and pull off the surfaces. The mechanism designed as a foot of climbing robots can vertically resist at least 1kg of load on rough surface. The findings provide a foundation for constructing a system for a rough-wall-climbing robot.

Graphene wrapped nitrogen-doped active carbon fibers (ACF@GR) of a core-shell structure were successfully prepared by a simple dip-coating method using natural silk as template. Compared to pure silk active carbon, the as-prepared ACF@GR composites exhibit high specific surface area in a range of 1628–2035 m 2 g −1 , as well as superior energy storage capability, an extremely high single-electrode capacitance of 552.8 F g −1 was achieved at a current density of 0.1 A g −1 in 6 M KOH aqueous electrolyte. The assembled aqueous symmetric supercapacitors are capable of deliver both high energy density and high power density, for instance, 17.1 Wh kg −1 at a power density of 50.0 W kg −1 , and 12.2 Wh kg −1 at 4.7 kW kg −1 with a retention rate of 71.3% for ACF@GR1-based supercapacitor.

Graphene nanosheets (GNs) functionalized attapulgite (ATTP)/sulfur (ATTP@GNs/S) composites were prepared through the melt-diffusion method, and investigated as cathode of lithium–sulfur (Li–S) batteries. Owing to the strong adsorption capability and sulfur/lithium polysulfides (Li 2 S n ) confinement of the natural ATTP nanofibers and partially reduced GNs, ATTP/S and ATTP@GNs/S exhibit improved electrochemical performance compared to elemental sulfur. The ATTP@GNs/S composite shows an initial discharge capacity of 1143.9 mAh g −1 , and a reversible capacity of ca. 512.0 mAh g −1 after 100 cycles at 0.1C, giving a capacity decay rate of as low as 0.5% per cycle. This research demonstrates the possibility of utilizing ATTP as sulfur host matrix or as cathode additives for enhanced energy storage capability of Li–S batteries.

Low-cost and high performance electrode materials are critical for rapid development and wide applications of supercapacitors. Herein, we report a cost-effective approach to prepare nitrogen-doped active carbon/graphene (N-AC/Gr) composites using renewable corn straw and soy protein as precursors, respectively. The as-prepared composites have moderate specific surface areas in a range of 1233.6–1412.9 m2 g–1 and abundant porosity. Furthermore, the composites demonstrate high single electrode gravimetric and volumetric specific capacitances of 378.9 F g–1 and 257.7 F cm–3 at 0.05 A g–1 and of 321.1 F g–1 and 213.2 F cm–3 at 20 A g–1, accounting for an excellent rate capability with a retention of 66.4% in 6 M KOH electrolyte. The assembled N-AC/Gr-based aqueous symmetric supercapacitor exhibits superior cycling durability with 93% retention after 10,000 cycles at 2 A g–1 and delivers a high energy density of 13.1 Wh kg–1 (11.1 Wh L–1) with a power density of 12.5 W kg–1 (10.6 W L–1).

Sandwich-like nitrogen-enriched porous carbon/graphene composites were prepared by carbonization of polyacrylonitrile (PAN) nanofiber paper with bulk-doped and/or surface-coated graphene oxide (GO), and followed by activation with KOH at high temperatures. The composites exhibit high specific surface areas in a range of 1957.2–2631.8 m 2 g −1 , as well as superior energy storage capability as electrodes for supercapacitors. A very high specific capacitance of 381.6 F g −1 at a current density of 0.1 A g −1 was achieved in 6 M KOH aqueous electrolyte for N-ACGrF@Gr1 that contains two types of graphene. According to the investigation results, the surface-coated graphene plays a more positive effect on improved supercapacitance than the bulk-doped graphene in the composites. Additionally, the assembled aqueous symmetric supercapacitors deliver a high energy density of 13.2 W h kg −1 at a power density of 25.0 W kg −1 , and 8.3 W h kg −1 at 4.7 kW kg −1 with a retention rate of 62.9%.

Reed straw-derived active carbon@graphene (AC@GR) hybrids were prepared by one-step carbonization/activation process using a mixture of reed straw and graphene oxide (GO) as raw materials and ZnCl2 as activation agent. The as-prepared hybrids exhibit high specific surface area in a range of 1971–2497 m2 g−1, abundant porosity, as well as excellent energy storage capability. The symmetric C//C supercapacitor using the hybrid obtained at 700 °C as electrodes demonstrates superior cycling durability, ca. 90 % retention after 6000 cycles at 2 A g−1, and a high energy density of 6.12 Wh kg−1 at a power density of up to 4660 W kg−1 in 6 M KOH aqueous electrolyte. The excellent capacitive performance is attributed to the synergistic effect of AC and GR.

To improve the properties of ground granulated blast furnace slag (GGBS) and utilize ground granulated blast furnace slag efficiently, this study investigates the effect of fineness on the hydration activity index (HAI) of ground granulated blast furnace slag. The hydration activity index of GGBS with six specific surface areas (SSAs) was characterized by the ratio of compressive strength of the prismatic mortar test block. The particle size distribution of GGBS with different grinding times was tested by laser particle size analyzer. The paste of different specific surface area GGBSs in different curing ages was investigated at the micro level by X-ray diffraction, scanning electron microscope, energy dispersive spectrometer, thermogravimetric scanning calorimeter, and differential scanning calorimeter. The effect of particle distribution of GGBS on the hydration activity index of different curing ages was studied by gray correlation analysis. The results indicated that the compressive strength and hydration activity index increases with the increase of a specific surface area of GGBS at different curing ages. The hydration activity index at different curing ages is almost a linear role for specific surface areas. With the increase in the specific surface area of GGBS, the content of Ca(OH)2 in paste decreases gradually. When GGBS was added into a mortar test block, the hydrate calcium silicate gel in paste changed from a high Ca/Si ratio to a low Ca/Si ratio. The 0&ndash, 10 micron particles of GGBS particle distribution were highly correlated with the hydration activity index at different curing ages.

Mn–Zn ferrite powders were produced from low-grade manganese ore (LMO) via the chemical co-precipitation method combined with the ceramic method, after the LMO was leached in sulfuric acid and the obtained solution was purified. The effect of the pH on the magnetic properties of Mn–Zn ferrite was investigated by the varying pH of the co-precipitation system. The crystal structure and phases of the samples were characterized by X-ray diffraction and infrared spectrum, respectively. The magnetic measurements were carried out on a vibrating sample magnetometer. The optimal sample was obtained with a saturation magnetization of 55.02 emu/g, a coercivity of 8.20 G and a remanent magnetization of 1.71 emu/g when pH is 7.5.

MnO2/graphene nanosheets (MnO2/GNs) hybrid composite can be prepared by spray-drying technique with either graphene oxide (GO) or hydrazine-reduced graphene as precursor. The characterization results of the as-synthesized composites indicate that MnO2 and GNs are uniformly distributed and intertangled forming porous microspheres in a diameter of 2–4 μm. This special secondary structure is beneficial for an intimate contact between MnO2 and GNs accounting for improved conductivity. In addition, the high surface area and abundant porosity enables aqueous electrolyte to penetrate deeply inside the hybrid microspheres, and facilitating the Na+ insertion/release process, which increases the utilization of active component resulting in enhanced supercapacitance. MnO2/graphene hybrid microspheres exhibit a good cycling performance as the intertangled graphene buffers the volume change of MnO2 during charge–discharge cycles.

A solid oxide fuel cell with a nickel-yttria stabilized zirconia cermet anode and a porous lanthanum strontium manganite cathode was used to generate electrical power directly from anaerobic digester gas and commercial diesel steam reformate. A diesel reformer was combined with the solid oxide fuel cell system in a single operating unit to convert diesel to electricity. To model anaerobic digester gas (ADG), a fuel gas mixture was prepared based on analytical data on real ADG from a local water cleaning facility. Electrochemical performance characterization involved power generation across a variety of external loads to characterize open circuit potential, maximum power densities and limiting current densities. The effects of anode poisoning from of sulfur compounds and their removal from the ADG fuel were studied.

The compressive strength of the contrast mortars and test mortars at different curing temperatures at different ages were tested. Effect of curing temperature on the strength of the test mortars and the contrast mortars was analyzed. The relative activity index and absolute activity index of the silica fume were studied. The mercury porosimetry method was used to test the pore structure of mortar specimens, and the improving effect of silica fume on the pore structure of mortar specimens under different curing temperatures was analyzed. The results show that with the increase of age, the decrease of curing temperature will cause the strength of mortar specimens to slow down. At the 3d and 7d ages, with the decrease of curing temperature, the absolute activity value of silica fume gradually increases. After 7 days of age, with the decrease of curing temperature, the absolute activity of silica fume gradually decreases. With the increase of curing age, the relative activity of silica fume decreases at first and then increases at 20°C and 10°C. The relative activity value of silica fume under the maintenance of 5°C and -3°C increased first and then decreased gradually. The addition of silica fume in the concrete improved the internal pore structure of the specimen, and the effect of curing temperature on the specimen was consistent.

The surface-modified dental barium glass with silane coupling reagent KH-570 was studied. The prepared samples before and after modification were characterized by static precipitation, angle of contact, transmission electron microscopy, X-ray photoelectron spectroscopy, Fourier transform infrared ray, and thermo-gravimetric analysis. Research showed that the KH-570 was bound on the surface of barium glass, a firm chemical bonding of KH-570 to barium glass and an organic layer was formed, and the maximum mass fraction of KH-570 coated on the barium glass surface measured was about 2.86%. The surface performance of modified barium glass changed from hydrophilic to hydrophobic. Mechanical tests revealed that the mechanical properties of composite resin filled by KH-570 modified barium glass improved simultaneously.