Laser powder bed fusion (L-PBF) technology offers significant advantages, such as lightweight and miniaturized product fabrication and short manufacturing cycles. Circular channels are widely ...utilized in hydraulic manifold blocks due to their favorable hydrodynamic properties. However, when manufactured using L-PBF, circular channels often exhibit shape deviations caused by residual stresses. In this study, Ti6Al4V (TC4) circular channels with various processing parameters were produced through L-PBF. The influence of scanning speed and laser power on the actual channel profile was investigated. A novel deformation prediction model for circular channels was established based on the Euler–Bernoulli theory. This model accurately predicts deformations resulting from residual stresses during horizontal manufacturing of circular channels using L-PBF, considering the interaction between forces and deformations across different manufactured layers. Furthermore, the model can be employed for channel shape compensation design. The results indicated excellent agreement between the proposed deformation prediction model and the profile of the experimentally manufactured samples. Using the channel shape compensation model for circular channels substantially can reduce the root mean square (RMS) deviation, thereby improving dimensional accuracy.
Fluid–solid erosion wear may damage the port structure and change the linear characteristics of the spool valve. They may also affect null characteristics and the control accuracy of the valve, ...resulting in production and safety accidents. In the present study, the prediction model of the orifice throttling coefficient and worn profile for engineering applications such as compensation control and life degradation assessment is established. The collision probability between particles and the wall surface is particularly considered based on the E/CRC erosion wear model. The relationship between the spool opening and the impact angle of particles is investigated numerically when developing collision probability model. Meanwhile, the influence of particle concentration, spool opening, and differential pressure on the orifice throttling coefficient and worn profile is analyzed by experiments, and the microcosmic surface morphology of the spool metering edge is analyzed by scanning electron microscopy (SEM). The results show that the impacting of solid particles on the orifice will result in extrusion-thin platelets flaking wear and deformation wear. The maximum relative error between the predicted results and the experimental measurements is 2.25%. Moreover, the predicted results of the model are in good agreement with the measured values under different particle concentrations, spool openings and differential pressure.
•The probability model of solid particle–orifice collision is proposed.•Based on the E/CRC model, models are developed for predicting the worn profile and orifice throttling coefficient.•The maximum error between the orifice throttling coefficient prediction values and the experimental measurements is 2.25%.•The impacting of solid particles on the orifice will result in extrusion-thin platelets flaking wear and deformation wear.
Laser powder bed fusion (L-PBF) technology is an appropriate scheme for producing intricate components with complex internal structures, such as the intricate flow channel networks in aircraft ...hydraulic manifolds. However, it is an enormous challenge to fabricate circular channels without support structures that exhibit low shape deviation and high surface quality through L-PBF. This study introduces an innovative annular gradient-forming process that divides the circular flow channel into three sections, namely the inner layer, the transition layer, and the substrate, sequentially from the inside to the outside along the radial direction. Throughout the L-PBF process, the laser energy density is incrementally increased for the inner layer, transition layer, and substrate. The research focuses on manufacturing Ti6Al4V (TC4) circular channels with a diameter of 10 mm, exploring various process parameters to achieve low surface roughness, high dimensional accuracy, and low porosity through the annular gradient process. The effectiveness of the proposed annular gradient process and its parameters is validated through the fabrication and testing of circular channels with diameters of 8 mm, 10 mm, and 12 mm. The results demonstrate that the root mean square deviation (RMS) of the horizontal circular channels using the annular gradient process is reduced by over 80%, and the surface roughness Ra is reduced by over 50%. Furthermore, the channels also have better mechanical properties.
•An innovative annular gradient process method is introduced for circular channels.•The effects of process parameters on forming quality of channels are investigated.•The annular gradient process effectively reduces dimensional deviations and surface roughness.•The annular gradient process ensures high strength and low porosity in channels.
Electro-hydraulic proportional servo valve (EHPSV) is a typical precision hydraulic component, widely used in construction machinery, aircraft, ships and other important equipment. When the ...electro-hydraulic proportional servo valve is working, the pollution particles in the hydraulic oil will cause erosion and wear of the valve element and seriously affect the control precision of the valve. In addition, the hydraulic system is a typical nonlinear system, if the traditional PID controller is used for control, the control precision of the system can not be guaranteed. In this paper, the typical valve controlling cylinder system in hydraulic system is taken as the research object. An ARC controller is designed to control the system, and an erosion wear prediction model is established by finite element simulation to control the valve-controlled cylinder system with high-quality flow compensation under the ARC control architecture. In this paper, the modeling and simulation of valve controlling cylinder system are carried out by MATLB/Simulink. The results show that the adaptive robust controller with erosion wear prediction model can effectively improve the control precision of proportional servo valve.
Aviation hydraulic integrated block is an important part of aircraft hydraulic system, but its large volume, mass weight and internal pipeline pressure loss greatly limit the increase of hydraulic ...system power density ratio, is one of the components with the greatest weight reduction potential in aircraft hydraulic system. The application of AM technology can greatly improve the design freedom of aviation hydraulic integrated block. Proper design can not only reduce weight and volume, but also improve the internal fluid performance. In this paper, by means of COMSOL, finite element analysis and simulation are carried out on the velocity field and pressure field of circular turning pipe, continuous radius change pipe and B-spline curve pipe. In this paper, the influence of structural parameters of continuous radius change pipe and B-spline curve pipe on pressure loss is investigated in detail. The simulation results show that compared with the traditional machined transition pipe, the circular turning pipe, continuous radius change pipe and B-spline curve pipe can improve the flow performance of the internal fluid, and reasonable structural parameters can further reduce the pressure loss. This result lays a theoretical foundation for the structural optimization design of the internal flow path of the additive manufacturing hydraulic integrated block.
In order to efficiently mitigate error propagation and reduce computational complexity, this paper proposes a scheme for traditional cooperative networks, named as dual-threshold symbol selective ...demodulate-and-forward. In the scheme, two log likelihood ratio (LLR)-based thresholds are devised to measure the reliability of received signals for the relay and the destination, respectively.One of the threshold guarantees that the relay only forwards reliable symbols, thus less error will be propagated to the destination. The other threshold is used at the destination for determining the reliability of symbols received from the source.The destination will directly demodulate reliable symbols received from the source. Otherwise, when the symbols received from the source are not reliable, the maximum ratio combiner (MRC) is used to combine symbols received from the source and the relay.Closed-form expression of the bit error probability (BEP) of the proposed scheme is derived and analyzed under binary phase shift keying (BPSK) modulation. Then, the relationship and closed-form solutions of two LLR-based thresholds are derived. Simulation results prove that the theoretical BEP of the proposed scheme closely matches the simulated ones. The proposed scheme can achieve high performance with low computational complexity compared to existing schemes.
Biological fluoride ion channels are sub-1-nanometer protein pores with ultrahigh F
conductivity and selectivity over other halogen ions. Developing synthetic F
channels with biological-level ...selectivity is highly desirable for ion separations such as water defluoridation, but it remains a great challenge. Here we report synthetic F
channels fabricated from zirconium-based metal-organic frameworks (MOFs), UiO-66-X (X = H, NH
, and N
(CH
)
). These MOFs are comprised of nanometer-sized cavities connected by sub-1-nanometer-sized windows and have specific F
binding sites along the channels, sharing some features of biological F
channels. UiO-66-X channels consistently show ultrahigh F
conductivity up to ~10 S m
, and ultrahigh F
/Cl
selectivity, from ~13 to ~240. Molecular dynamics simulations reveal that the ultrahigh F
conductivity and selectivity can be ascribed mainly to the high F
concentration in the UiO-66 channels, arising from specific interactions between F
ions and F
binding sites in the MOF channels.
As the newest two members of the carbon materials family, carbon dots (CDs) and graphene oxide (GO) possess many excellent optical properties resulting in a wide range of applications. In this work, ...we successfully synthesized CDs with a high-quantum-yield, and labeled them on oligodeoxyribonucleotide (ODN). The fluorescence of resultant CDs-labeled oligodeoxyribonucleotide (ODN–CDs) was quenched by GO via fluorescence resonance energy transfer. In the presence of Hg2+, the fluorescence was recovered by the release of ODN–CDs from GO due to the formation of T–Hg2+–T duplex. In the light of this theory, we designed a simple, highly sensitive and selective fluorometric Hg2+ sensor based on CDs-labeled oligodeoxyribonucleotide and GO without complicated, costly and time-consuming operations. Under the optimal conditions, a linear relationship was obtained between relative fluorescence intensity and the concentration of Hg2+ in the range of 5–200nM (R2=0.974). The present GO-based sensor system is highly selective toward Hg2+ over a wide range of metal ions and has a detection limit of 2.6nM. This method is reliable, and has been successfully applied for the detection of Hg2+ in practical samples.
•We synthesized carbon dots (CDs) with a quantum yield as high as ca. 75.0%.•CDs were firstly labeled on T-rich oligodeoxyribonucleotide to be probe of Hg2+.•The fluorescence of CDs-labeled ODN was quenched by GO and recovered by adding Hg2+.•We designed Hg2+ biosensor by combining FRET of GO and CDs with selectivity of ODN.•CDs showed potential in the fluorescent label technology.
Cement-based materials with a low water/binder ratio contain a high number of unhydrated cement particles, which implies that a rehydration reaction occurs when they encounter water again. This study ...aimed to explore how rehydration influences the macroscopic and microscopic properties of cement-based materials. The key study findings included that rehydration could still occur in cement-based materials after one year of hydration, and that the capacity for rehydration-induced repair or damage to cement-based materials depended on whether their internal pores could accommodate rehydration products. During rehydration, the compressive strength and porosity of the specimens were found to first increase and then decrease. The capillary water absorption coefficient decreased continuously over a rehydration period of 120 days. As the water/binder ratio rose, the rehydration rate first increased and then decreased. First, the influence of temperature on the rehydration rate was more noticeable when the water/binder ratio was below 0.3; second, whereas adding large amounts of fly ash and silica fume did not prove to be conducive to repairing and enhancing cement-based materials undergoing rehydration, adding slag and small quantities of silica fume, or alternatively compounding small amounts of silica fume and fly ash could improve the repair and enhancement effects of rehydration.
•Users are strongly influenced by priming with different development origin of image schemas in GES.•EIS-priming results in final gesture set that are higher in initial and overall ...learnability.•LIS-priming improves gesture proposal production in comparison to no-priming condition.
Gesture elicitation study is an effective method to design gestures for various contexts. Through involving end-users, GES results in intuitive gestures because they directly reflect end-users’ mental models and preferences. However, limited by personal experience, end-users are not capable of taking full advantages of technology while proposing gestures, which is referred as legacy bias. To overcome this, previous studies demonstrate that users’ performance can be improved by priming, such as viewing gestures, watching fictional movies, and experiencing framed scenarios. This research extends this line of studies by considering the developmental origin of image schemas in priming. More specifically, we compared the influences of no-priming, priming with early image schemas (EIS), and priming with late image schemas (LIS) on GES. Controlled experiments were conducted (N = 120) along the three stages of GES: users’ generation of gestures (Experiment 1), final gesture sets (Experiment 2), and end-users’ learnability of gestures (Experiment 3). Results show that users are largely influenced by developmental origin of image schemas in priming. LIS-priming improve gesture proposal production in comparison to no-priming condition. As for end-users’ evaluation, EIS-priming gestures exhibit higher initial and overall learnability.
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