Several consolidation cycles were performed to study the impact of processing parameters on void content, ultrasonic NDT and mechanical performance of CF/PEEK composites. A series of +45/−454S ...laminates were manufactured by out-of-autoclave technologies including vacuum bag only, hot-press, and automatic lay-up with in-situ consolidation. A range of porosity between 0 and 19% of void content was assessed by varying the processing temperature from 340 to 500 °C and pressure from 0.25 to 1.5 MPa. Void content, shape and location were characterized by using C-scan, matrix digestion and 2D microscopy. Mechanical characterization including in-plane shear and interlaminar shear testing was performed. The results show a critical void content where properties start to decrease at a given drop-off rate. The results suggest that each processing technology should have its own quality control criteria. The proposed methodology is useful for engineering applications of thermoplastic composites and the creation of NDT acceptance criteria.
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•The energy performance of a solar-powered VMD plant was evaluated.•The effect of the applied vacuum pressure on the specific energy consumption was demonstrated.•The effect of solar ...radiation on the energy performance of the installation was analyzed.•The impact of recycling hot cooling water used for steam condensation on SEC, GOR and daily production was discussed.
In this paper, a study of the energy performance of a solar powered vacuum membrane distillation was investigated on four typical days that represent the four seasons of the year namely: the equinoxes (March 21st and September 21st) and the solstices (June 21st and December 21st), through the widely used energy criteria such as specific energy consumption, gained output ratio and heat recovery factor. The results indicate that the energy performance of the process is strongly linked to the solar irradiation and as long as the VMD is coupled with solar energy, the process could be competitive with industrialized desalination technologies such as RO, MSF and MED. Besides, the effect of the applied vacuum level on the specific energy consumption was examined. Obviously, the results reveal that for minimum SEEC an optimal vacuum pressure is between 5000 and 10000 Pa. As well a technique to optimize the energy performance by recycling hot cooling water, used for steam condensation, was discussed. An amelioration of about 35%, 26% and 31%, during the hottest day (June 21st) and of about 22%, 19% and 21%, during the coldest (December 21st) in the GOR, the SEC and the daily production could be achieved.
Industry is facing the management of geometrical deviations along the entire lifecycle of the product. It is helped by digital twin tools that may minimise the geometrical deviations from nominal of ...products. The new digital twin tools allow to manage geometrical variations through a set of steps fully related by modern information and communication technologies that establish a continuous and unambiguous flow of information among the different steps of this digital process along the whole product lifecycle. They are based on data coming from manufacturing, assembly and inspection. The available large data sets from manufacturing and inspection allow to develop new and more accurate simulation models that realistically consider form deviations and process signature, i.e. the pattern left by the manufacturing process on the produced part surfaces. The present work introduces a digital twin tool to support the lightweight design of assemblies in composite material. It establishes a continuous and unambiguous flow of variation information from the part design to assembly, passing through manufacturing by considering the manufacturing signature. It was applied to a case study and the obtained results agree with the experimental ones.
A novel process for NO and SO2 simultaneous removal using a vacuum ultraviolet (VUV, with 185 nm wavelength)-activated O2/H2O/H2O2 system in a wet VUV–spraying reactor was developed. The influence of ...different process variables on NO and SO2 removal was evaluated. Active species (O3 and ·OH) and liquid products (SO3 2–, NO2 –, SO4 2–, and NO3 –) were analyzed. The chemistry and routes of NO and SO2 removal were investigated. The oxidation removal system exhibits excellent simultaneous removal capacity for NO and SO2, and a maximum removal of 96.8% for NO and complete SO2 removal were obtained under optimized conditions. SO2 reaches 100% removal efficiency under most of test conditions. NO removal is obviously affected by several process variables. Increasing VUV power, H2O2 concentration, solution pH, liquid-to-gas ratio, and O2 concentration greatly enhances NO removal. Increasing NO and SO2 concentration obviously reduces NO removal. Temperature has a dual impact on NO removal, which has an optimal temperature of 318 K. Sulfuric acid and nitric acid are the main removal products of NO and SO2. NO removals by oxidation of O3, O·, and ·OH are the primary routes. NO removals by H2O2 oxidation and VUV photolysis are the complementary routes. A potential scaled-up removal process was also proposed initially.
Membrane crystallization (MCr) is emerging as an interesting candidate to extract additional freshwater and raw materials from high-concentrated solutions. Traditionally, MCr has been carried out by ...using polymeric membranes that have limited chemical and mechanical stability. These shortcomings can be overcome by using ceramic membranes. The current study describes the preparation and testing of two hydrophobic ceramic membranes synthesized trough sol-gel process, and combined phase-inversion and sintering method. The first membrane (CM-L) was synthesized by coating hydrophobic polymethylsilsesquioxane aerogels on alumina membrane supports via a sol-gel process. The membrane showed stable hydrophobic character in membrane distillation and crystallization tests but very low flux. To obtain high flux, a second type (CM-S) membrane was prepared by applying Fluoroalkylsilanes (FAS) (1H, 1H, 2H, 2H‑perfluorooctyltriethoxysilane) hydrophobic agent at the relatively thin and more porous as-sintered alumina hollow fibers. The suitability of both membranes for MCr process was analyzed by crystallizing NaCl and LiCl. By using 1 M NaCl and 13 M LiCl aqueous solutions, and under the same operative conditions, CM-S membrane exhibited average flux higher than CM-L membrane. The performance of both the membranes, in terms of hydrophobic character, remained stable throughout the performed tests.
•Novel ceramic membranes for MCr/MD process•Influence of membrane characteristics on MCr process•Membrane assisted crystallization in desalination
We describe fuel-free, near-infrared (NIR)-driven Janus mesoporous silica nanoparticle motors (JMSNMs) with diameters of 50, 80, and 120 nm. The Janus structure of the JMSNMs is generated by vacuum ...sputtering of a 10 nm Au layer on one side of the MSNMs. Upon exposure to an NIR laser, a localized photothermal effect on the Au half-shells results in the formation of thermal gradients across the JMSNMs; thus, the generated self-thermophoresis can actively drive the nanomotors to move at an ultrafast speed, for instance, up to 950 body lengths/s for 50 nm JMSNMs under an NIR laser power of 70.3 W/cm2. The reversible “on/off” motion of the JMSNMs and their directed movement along the light gradient can be conveniently modulated by a remote NIR laser. Moreover, dynamic light scattering measurements are performed to investigate the coexisting translational and rotational motion of the JMSNMs in the presence of both self-thermophoretic forces and strong Brownian forces. These NIR-powered nanomotors demonstrate a novel strategy for overcoming the necessity of chemical fuels and exhibit a significant improvement in the maneuverability of nanomotors while providing potential cargo transportation in a biofriendly manner.
Air-stable doping of transition metal dichalcogenides is of fundamental importance to enable a wide range of optoelectronic and electronic devices while exploring their basic material properties. ...Here we demonstrate the use of benzyl viologen (BV), which has one of the highest reduction potentials of all electron-donor organic compounds, as a surface charge transfer donor for MoS2 flakes. The n-doped samples exhibit excellent stability in both ambient air and vacuum. Notably, we obtained a high electron sheet density of ∼1.2 × 1013 cm–2, which corresponds to the degenerate doping limit for MoS2. The BV dopant molecules can be reversibly removed by immersion in toluene, providing the ability to control the carrier sheet density as well as selective removal of surface dopants on demand. By BV doping of MoS2 at the metal junctions, the contact resistances are shown to be reduced by a factor of >3. As a proof of concept, top-gated field-effect transistors were fabricated with BV-doped n+ source/drain contacts self-aligned with respect to the top gate. The device architecture, resembling that of the conventional Si transistors, exhibited excellent switching characteristics with a subthreshold swing of ∼77 mV/decade.
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•Membrane contactors with renewable CO2 absorbents are used for biogas upgrading.•Mass transfer resistance in the membrane contactor for biogas upgrading is studied.•Temperature has ...little effect on CO2 absorption rates of the renewable absorbents.•Biogas upgrading performance is highly dependent on the gas and liquid flow rates.•This study paves a new way to use renewable absorbents for carbon minimization.
This study employs novel renewable absorbents derived from biogas slurry (BS) for biogas upgrading via membrane contactors. CO2 absorption capacity of biogas slurry can be enhanced by adding alkali solutions, vacuum regeneration or vacuum membrane distillation (VMD). These methods are used to produce four types of renewable CO2 solvents, including vacuum regenerated BS, recovered aqueous ammonia (RAA) from BS by VMD, calcium oxide treated BS and potassium hydroxide treated BS. These renewable absorbents for CO2 capture from biogas by membrane contactors are investigated. CO2 removal efficiency reduces but absorption rates increase with the rise in CO2 volume fraction in the feed gas stream. Absorption temperature has a limited effect on CO2 absorption rates of the renewable absorbents. RAA shows the best CO2 absorption performance among the four types of renewable absorbents in the membrane contactor. RAA flowing on the tube side leads to a 50% higher CO2 removal efficiency compared with RAA on the shell side. At low gas flow rates, partial absorbents and hollow fibers may not be utilized. Thus, selection of membrane module parameters, including the length of module, the number of hollow fibers, biogas flow rates and absorption performance, should be carefully considered when using membrane contactors for biogas upgrading.
A low band gap quinolizino acridine based molecule was designed and synthesized as new hole transporting material for organic–inorganic hybrid lead halide perovskite solar cells. The functionalized ...quinolizino acridine compound showed an effective hole mobility in the same range of the state-of-the-art spiro-MeOTAD and an appropriate oxidation potential of 5.23 eV vs the vacuum level. The device based on this new hole transporting material achieved high power conversion efficiency of 12.8% under the illumination of 98.8 mW cm–2, which was better than the well-known spiro-MeOTAD under the same conditions. Moreover, this molecule could work alone without any additives, thus making it to be a promising candidate for solid-state photovoltaic application.
To investigate the effect of RDX on the explosion reaction mechanism of FOX-7 based aluminized explosives in vacuum environment, the explosion field temperature of FOX-7 based aluminized explosives ...and RDX/FOX-7 based aluminized explosives were measured in an isolated explosion chamber. The results show that adding RDX would increase the equilibrium temperature of explosion field of FOX-7-based aluminized explosives. The equilibrium temperature of FOX-7-based aluminized explosives and RDX/FOX-7-based aluminized explosives increases first and then decreases with the increasing of Al content, which shows the highest equilibrium temperature as the Al content is 30%. When the Al content is less than 25%, the explosion peak temperature of FOX-7-based aluminized explosives would increased by adding RDX, and when the aluminium content is more than 30%, the explosion peak temperature of FOX-7-based aluminized explosives can be reduced by adding RDX.
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