Planar Surface Research Articles

Stimulus-Responsive Gas Marbles as an Amphibious Carrier for Gaseous Materials.

Gas marbles are a new family of particle-stabilized soft dispersed system with a soap bubble-like air-in-water-in-air structure. Herein, stimulus-responsive character is successfully introduced to a gas marble system for the first time using polymer particles carrying a poly(tertiary amine methacrylate) (pKa ≈7) steric stabilizer on their surfaces as a particulate stabilizer. The gas marbles exhibited long-term stability when transferred onto the planar surface of liquid water, provided that the solution pH of the subphase is basic and neutral. In contrast, the use of acidic solutions led to immediate disintegration of the gas marbles, resulting in release of the inner gas. The critical minimum solution pH required for long-term gas marble stability correlates closely with the known pKa value for the poly(tertiary amine methacrylate) stabilizer. It also demonstrates amphibious motions of the gas marbles.

Alkali-fluoride-salt-accelerated oxidation behavior of graphite under air atmosphere

Air ingress accident scenarios may result in the oxidation of graphite matrix materials and cause serious safety problems in molten salt reactor. However, the oxidation behavior of the molten-salt-infiltrated graphite remains elusive. In this study, the effect of alkali fluoride salts (LiF, NaF, KF and ternary salt FLiNaK) on the oxidation behavior of graphite powder under air atmosphere was investigated. Thermogravimetric analysis and oxidation tests manifest that the initial oxidation temperature of the graphite is reduced from 720 °C to 510–610 °C, because of the presence of the alkali fluoride salts. The catalytic oxidation effect follows the order of KF > NaF > LiF. Careful characterizations reveal that the pristine graphite is mainly oxidized at the graphite edges, while salt-infiltrated graphite is mainly damaged at the graphitic basal planes. Density functional theory calculations suggest that the doping of alkali metal atoms does not change the physical adsorption feature of the oxygen molecule on the graphite plane surface, but increases its adsorption energy to facilitate the graphite oxidation reactions.

Siloxane Containing Polyether Groups-Synthesis and Use as an Anti-Biocorrosion Coating.

In the presented study, the effectiveness of a siloxane polyether (HOL7) coating on glass against microbiological colonization was assessed using microalgae as a key component of widespread aerial biofilms. The siloxane polyether was successfully synthesized by a hydrosilylation reaction in the presence of Karstedt's catalyst. The product structure was confirmed by NMR spectroscopy and GPC analysis. In addition, the thermal stability of HOL7 was studied by thermogravimetric measurement. Subsequently, the surfaces of glass plates were modified with the obtained organosilicon derivative. In the next step, a microalgal experiment was conducted. A mixture of four strains of algal taxa isolated from building materials was used for the experiment-Chlorodium saccharophilum PNK010, Klebsormidium flaccidum PNK013, Pseudostichococcus monallantoides PNK037, and Trebouxia aggregata PNK080. The choice of these algae followed from their wide occurrence in terrestrial environments. Application of an organofunctional siloxane compound on the glass reduced, more or less effectively, the photosynthetic activity of algal cells, depending on the concentration of the compound. Since the structure of the compound was not based on biocide-active agents, its effectiveness was associated with a reduction in water content in the cells.

Molecularly imprinted nanogels as synthetic recognition materials for the ultrasensitive detection of periodontal disease biomarkers.

Periodontal disease affects supporting dental structures and ranks among one of the top most expensive conditions to treat in the world. Moreover, in recent years, the disease has also been linked to cardiovascular and Alzheimer's diseases. At present, there is a serious lack of accurate diagnostic tools to identify people at severe risk of periodontal disease progression. Porphyromonas gingivalis is often considered one of the most contributing factors towards disease progression. It produces the Arg- and Lys-specific proteases Rgp and Kgp, respectively. Within this work, a short epitope sequence of these proteases is immobilised onto a magnetic nanoparticle platform. These are then used as a template to produce high-affinity, selective molecularly imprinted nanogels, using the common monomers N-tert-butylacrylamide (TBAM), N-isopropyl acrylamide (NIPAM), and N-(3-aminopropyl) methacrylamide hydrochloride (APMA). N,N-Methylene bis(acrylamide) (BIS) was used as a crosslinking monomer to form the interconnected polymeric network. The produced nanogels were immobilised onto a planar gold surface and characterised using the optical technique of surface plasmon resonance. They showed high selectivity and affinity towards their template, with affinity constants of 79.4 and 89.7nM for the Rgp and Kgp epitope nanogels, respectively. From their calibration curves, thetheoretical limit of detection was determined to be 1.27nM for the Rgp nanogels and 2.00nM for the Kgp nanogels. Furthermore, they also showed excellent selectivity against bacterial culture supernatants E8 (Rgp knockout), K1A (Kgp knockout), and W50-d (wild-type) strains in complex medium of brain heart infusion (BHI).

1D analytic and numerical analysis of thin film heat transfer gauges and infra-red cameras in non-planar applications

The impulse response method is widely used for heat transfer analysis in turbomachinery applications. Traditionally, the 1D method assumes a: linear time invariant, isotropic, semi-infinite block with planar surfaces and does not accurately model the true geometric behaviour. This paper evaluates the error introduced by the planar assumption and outlines the required modifications for accurate freeform surface analysis. Adapted cylindrical basis functions are defined for the impulse response method and used to evaluate the impact of the 1D planar assumption. The analytic solutions for both convex and concave surfaces are presented. A penta-diagonal algorithm, for a modified numerical Crank-Nicolson scheme, is also evaluated for fast stable implementation of curved geometry simulation. The scheme shows comparable performance to the impulse response, whilst removing the requirement for linear time invariance. The new methods are demonstrated in the case of aerothermal analysis for heat transfer in a turbine nozzle guide vane. A 3D ANSYS simulation is used as a benchmark and further highlights the importance of the curvature effects. The methods are extended using curvature mapping for infra-red camera data, enabling direct 3D thermal simulation or the fast calculation of freeform curvature. This paper defines the methodology to analyse heat transfer measurements on non-planar geometry.

Recycling of Waste Plastic PET on Asphalt Concrete (AC) by Using Application of Response Surface Methodology: Effect of PET on AC Formulated by Duriez Model

The wet recycling process of plastic waste was used to design a composite material (asphalt concrete) following the Duriez method. This process aims to improve the rheological performance of asphalt concrete by transforming PET on powdery and added to bitumen. To attend this objective, Doehlert' surface plane was used to assess how the asphalt rate, the PET rate and size, and then the aggregate rate affected the stability (wet and dry) and, in turn, the immersion/compression strength index (RI/C), the absorption capacity, the compactness as well as the void that could be filled by the 0/10 AC (asphalt concrete). All quadratic multivariate polynomial models with interactions were obtained and validated in order to optimize the responses. Thus, the physical characterization made it possible to obtain an asphalt concrete with good mechanical characteristics. In addition, it was observed that the selected factors had a different impact on the responses, which are: IR/C; the water absorption capacity, compactness and void filled by the binder by significantly increasing or decreasing them in simple, quadratic and interaction contributions. From the multi-response optimization, the objective was to obtain a composite material (Asphalt-PET-Aggregates) with has the best rheological characteristic, resulted in the following compromise: Bitumen rate 7%, PET 6% of asphalt, PET size 0,5mm; Aggregate content 93%. The simulated optimal values yielded the following responses were: 0.77 RI/C, immersion/compressive strength (Y.<SUB>RI/C</SUB>); 2.9%, absorption capacity (Y.<SUB>WAC</SUB>); 94%, compactness (Y.<SUB>C</SUB>); 71% void filled by asphalt (Y.<SUB>VFA</SUB>)

X-Ray Diffraction Measurements for Inconel 718 Alloy Elements Created by Incremental Methods

Abstract The work presented is the result of the implementation of diffraction measurements: phase composition and stresses resulting from additive manufacturing process of nickel superalloy Inconel 718 components print. With the help of diffraction methodologies, the key parameters from the point of view of the quality of prints and their strength were determined. The existence of individual phases in the material after printing was demonstrated, and the surface variation of the stress values was presented, showing its dependence on the geometry of the printed part – measurements were made at various points on the surface of samples with different geometries. In addition, the variation of the stress level was shown depending on the distance of the measurement point from the build platform on which the additive manufacturing process was carried out. Components were printed on the surface of a single build plate in order to study the effect of printing differently oriented samples with respect to the platform geometry, as well as the mutual effect of the temperature of samples printed first on the stress state of elements printed in subsequent steps of the procedure, and the effect of the temperature of elements printed later on the rate of temperature decrease, and consequently on the stress state, of elements printed first.

Magnetic anisotropy of NiFeP/Cu composite wire induced by chemical plating under DC current

NiFeP/Cu composite wires were fabricated by chemical plating under DC current. In this work, DC current was adjusted from 0 to 100 mA and the influence of current on the surface morphology, magnetic properties and GMI effect was investigated. It is found that the DC current has little impact on the composition of the coating. However, with the change of current, the surface morphology, plating rate and magnetic properties of the coating have undergone significant changes which in turn affect the GMI effect. As a result, when the appropriate current is applied, a transverse magnetic structure with an anisotropy angle of approximately 26 degrees can be generated, enabling a maximum GMI ratio of 1964 % and a field sensitivity of 463 %/Oe, which shows potential practical application in the magnetic sensors.

Performance of a novel loop heat pipe coupled with micro vapor-driven jet injector – An experimental and numerical study

Loop heat pipe (LHP) is an efficient phase-change heat transfer device which has been widely applied in cooling high-power electronics on ground and in spacecraft. In previous work, a novel LHP coupled with vapor-driven jet injector (VDJI) has been proved to be feasible and shows excellent performance, namely LHPI. However, due to the lack of pressure data during LHP operation, the coupling mechanisms of VDJI and LHP remain unknown. Especially, the heat-mass transfer between high-speed vapor and subcooled liquid inside VDJI, which has great influence on the LHPI, need to be investigated to guide the design of the LHPI. In this paper, the start-up process, steady-state operation characteristic of LHPI and internal flow field of VDJI were investigated experimentally and numerically. By using the pore-forming sintering and integrated sintering method, the bi-porous wick was prepared and embedded on the base plate surface of evaporator, which brought a significant improvement in its performance. The results indicated that the LHPI could operate under a power of 600 W (50.0 W/cm2) without dry-out. Maintaining the heating wall temperature within 85 °C, the minimum thermal resistance of the LHPI with bi-porous and integrated sintered wick was below 0.18, and the maximum heating power can reach up to 404 W, which are 60% lower and 52.5% higher than mono-porous wick, respectively. In addition, four operation modes of VDJI were classified as low-efficiency mode, normal-injection mode, restricted expansion mode and superheated mode. The operation modes of VDJI had great influence on the performance of LHPI. In normal-injection mode, the entrainment ratio of VDJI exceeded 100, which resulted in the lowest thermal resistance of LHPI. For long-term operation of LHPI, the VDJI is suggested keep operating in normal-injection mode. Moreover, by using 3D numerical simulation method, the internal flow structure of the VDJI was obtained to gives an insight into mechanisms of these four operation modes. The numerical results showed the profile of compression waves and confirmed the existence of condensation shock wave in VDJI.

Mechanical Properties of Glass Plate During Anticlastic Cold Bending

Anticlastic glass surfaces play a significant role in free-form glass facades. For realizing anticlastic surface, cold bending by loading at the corner of the plate is more adaptive and more economic than traditional hot bending method. Previous research on anticlastic cold bending mainly focuses on the description of instability phenomenon and qualitative analysis of parameters. However, the failure mechanisms of glass plates during cold bending and the influence of lamination remains unclear. In this paper, the anticlastic cold bending test was conducted to explore the influence of various factors, including aspect ratio, scale and composition of the plates. Subsequently, an effective finite element model was established and validated by test results, which is used for further explore the cold bending controlling condition for better engineering practice. The failure modes are considered as instability and strength failure. For laminated glass, maximum stresses can be derived from monolithic glass based on equivalent thickness method. The instability is induced by the compression area in the middle surface of glass plate which is significantly influenced by the composition of the laminates. Consequently, thin glass laminates exhibit enhanced stability because a reduced glass to PVB thickness ratio changes the compression area from bi-directional to uni-directional.

Enhancement of the microwave absorption properties of the SrFe12O19@Fe3O4@rGO composite material

In this work, graphene oxide (GO) was prepared via the Hummers’ method, whereas SrFe12O19, SrFe12O19@Fe3O4, and SrFe12O19@Fe3O4@rGO were fabricated using the hydrothermal techniques. The samples' phase structure, surface morphology, magnetic properties, and electromagnetic wave absorption characteristics were studied and compared. Findings show that the Fe3O4 particles adhered to the surface of the SrFe12O19 hexagonal plates, and the combination of SrFe12O19@Fe3O4 foam flakes and two-dimensional graphene rGO could enhance the absorption electromagnetic wave performance. The composite SrFe12O19@Fe3O4@rGO sample exhibited an ideal impedance matching within the frequency f range of 11 GHz–12.4 GHz. The minimum reflection loss reached −62.3 dB at 12.2 GHz with a thickness of 2 mm. With a thickness of 2 mm, the effective absorption bandwidth obtained the value of −20 dB, covering a range of 9.3 GHz. The composite SrFe12O19@Fe3O4@rGO sample, which shows the highest performance both in reflectivity and bandwidth, can find potential application in microwave absorptions.

The Comparison of Surface Dose in Vivo Dosimetry Using 3D-CRT and IMRT Technique on Breast Cancer Case

The aim of this study is to verify the adequacy of the surface radiation dose calculated by the Treatment Planning System (TPS) using 3DCRT and IMRT technique with the dose measured by the TLD-100, referring to the report of the American Association of Physicists in Medicine Task Group No.219 (AAPM-TG No.219). This research process began with annealing the TLD-100 at the Research Center for Safety Technology Metrology and Nuclear Quality of the National Innovation Research Agency (PRTKMMR-BRIN), followed by scanning the TLD-100 on the surface of the phantom plate using a CT simulator. In addition, the TLD-100 was calibrated with different radiation doses (0; 20; 50; 80; 100; 150; 200; 250; 370) cGy. Verification of the surface radiation dose was performed by calculating the TPS surface dose by Patient Specific Quality Assurance (PSQA) and comparing it with the dose measured by the TLD-100. The result is Radiation techniques such as IMRT are more conformal than 3D-CRT because they precisely control dose intensity, making the TLD dose in IMRT closer to TPS. Differences in detector types such as TLD also affect the results of radiation dose measurements. Continuous assessment of patient dose is important for the safety of radiation therapy.

Non-adhesive and adhesive contacts of an elastic quarter-or eighth-space with freely sliding sides

The contact of an elastic quarter- or eighth-space is studied under the condition that the movement of the side surface of the quarter-space is constrained: It can slide freely along the plane of the side surface but its normal movement is blocked (for example, by a rigid wall). The solution of this contact problem can be easily achieved by additionally applying a mirrored load to an elastic half-space. Non-adhesive contact and the Johnson-Kendall-Roberts (JKR)-type adhesive contact between a rigid sphere and an elastic quarter-space under such a boundary condition is numerically simulated using the fast Fourier transform (FFT)-assisted boundary element method (BEM). Contacts of an elastic eighth-space are investigated using the same idea. Depending on the position of the sphere relative to the side edge, different contact behavior is observed. In the case of adhesive contact, the force of adhesion first increases with increasing the distance from the edge of the quarter-space, achieves a maximum, and decreases further to the JKR-value in large distance from the edge. The enhancement of the force of adhesion compared to the half-space-contact is associated with the pinning of the contact area at the edge. We provide the maps of the force of adhesion and their analytical approximations, as well as pressure distributions in the contact plane and inside the quarter-/eighth-space.

Development of a five-axis printer for the fabrication of hybrid 3D scaffolds: From soft to hard phases and planar to curved surfaces

Three-dimensional (3D) printing of hybrid scaffolds with material gradients, combining soft and hard phases, is an appealing frontier in additive manufacturing. However, most 3D printers are limited to either three-axis or mono-material capabilities, rendering them unsuitable for fabricating hybrid scaffolds. Additionally, printing on curved surfaces requires advanced printing capabilities. Our work aims to advance additive manufacturing by developing a hybrid piezoelectric inkjet-extrusion printer equipped with five-axis functionalities. The printer could be used to fabricate customized hybrid scaffolds, surpassing conventional mono-material or linear three-axis printing strategies. The soft phase comprises a low-viscosity photocurable resin and a high-viscosity peptide hydrogel, while the hard phase comprises 3D-printed polylactic acid and hydroxyapatite parts. To validate the system, we fabricated three hybrid scaffolding use cases, characterized by multi-material porous structures fabricated on planar, single-curved, and free-form surfaces. The scaffolds were subsequently analyzed using digital microscopy to assess their accuracy, particularly the feature sizes of pores and struts (i.e., 0.8–3.6 mm). In the first part of the study, we demonstrated the versatility of inkjet and extrusion printing by hybrid printing an interconnected network in the soft phase on top of a planar ceramic hard phase. A pore width and height deviation of 6% was achieved compared to the intended design. In the second part of the study, we evaluated the 3D inkjet printing of a multi-material porous scaffold on a single-curved surface for osteochondral defects. The circumferential pore width and radial pore height deviated by 0.8% and 2%, respectively. Finally, we inkjet-printed a mesh structure on a free-form surface, which acted as a membrane for palatal implants. In this case, the pore width deviations were -16% in the printing direction and 2% perpendicular to the printing direction.

Study on shear surface morphology and failure mechanism of soil-rock mixture under wet-dry cycle action

The present study investigates the failure modes and formation mechanisms of shear surfaces in soil-rock mixtures from various perspectives. Firstly, through in-situ direct shear tests, two main shear failure modes, namely planar and non-planar, are identified. Subsequently, using PFC 2D numerical simulation, an in-depth exploration of the characteristics and causes of these two typical failure modes is conducted. The findings reveal that in the natural state, the material is relatively dry, and the matrix suction within the soil-rock mixture is significant. During shearing, the inter-particle force chains are prone to rupture, exhibiting characteristics akin to brittle failure. This leads to nearly planar shear surfaces, with force chain ruptures primarily localized near the planar regions adjacent to the shear surface. However, after multiple dry-wet cycles, the plastic enhancement of the soil-rock mixture reduces the matrix suction to almost zero. The continuous rupture and reorganization of force chains deepen the shear band under their influence, resulting in non-planar shear surfaces. It is noteworthy that the characteristic point fitting curve of non-planar shear surfaces exhibits a nonlinear trend. In summary, our study elucidates the evolution process and causes of shear surface morphology in soil-rock mixtures, which holds significant implications for understanding their mechanical properties and engineering behavior.

Flexible anisotropic magnetoresistive sensors for novel magnetic flux leakage testing capabilities

Rigid magnetic field sensors such as anisotropic magnetoresistive (AMR), giant magnetoresistive (GMR) and Hall sensors have been used for years and have become industry standard for electromagnetic non-destructive testing (NDT). Recent technological developments in the field of flexible electronics allow for the fabrication of reshapeable magnetic field sensors on flexible substrates via thin-film deposition or printing. The magnetic properties of these sensors have comparable characteristics to industry-standard rigid magnetic field sensors, with the added ability of adapting to the surface of complex components and scanning in contact with the sample surface. This improves defect detectability and magnetic signal strength by minimizing the scanning lift-off (LO) distance. In this article flexible AMR sensors mounted on a rotative mechanical holder were used to scan a semi-circular ferromagnetic sample with 3 reference defects via magnetic flux leakage (MFL) testing, thus demonstrating the applicability of this type of sensors for the scanning of curved samples. In order to benchmark the performance of these sensors in comparison to industry standard rigid magnetic field sensors, a ferromagnetic sample with 10 reference defects of different depths was scanned employing flexible AMR and rigid GMR sensors. Defects with depths ranging from 110μm up to 2240μm were detected with an signal-to-noise ratio (SNR) of 2.7 up to 27.9 (for flexible AMR sensors) and 6.2 up to 72.3 (for rigid GMR sensors), respectively. A 2D magnetometer mapping of the sample with a spatial scanning step of 10×50μm2 (flexible AMR) and 16×100μm2 (rigid GMR) was obtained. The results show that this type of sensor can be used for high-resolution and high-detail mapping of defects on the surface of planar and non-planar ferromagnetic samples since the scanning lift-off distance is equal to the substrate thickness of 20μm for in-contact scanning. The SNR comparison between flexible and rigid sensors shows that the performance of the flexible AMR sensors employed is not very far behind the performance of the rigid GMR sensors used.

Hyper-Progressive Real-Time Detection Transformer (HPRT-DETR) algorithm for defect detection on metal bipolar plates

Aiming to address common defects such as scratches, cracks, bumps, and indentations on the surface of metal bipolar plates, this thesis proposes an algorithm called HPRT-DETR for detecting defects on metal bipolar plates. The algorithm aims to address issues such as small defects, complex backgrounds, and low detection accuracy. To enhance the performance of the algorithm, we adopt the DA to improve the AIFI module. This enhancement enables the algorithm to focus on the defective region, helping it capture more informative features. Meanwhile, we have implemented Zoom-cat scaling splicing and SSF to enhance the multi-scale feature fusion capability of the network in the CCFM module. Additionally, we have introduced the NWD metric loss to reduce sensitivity to small target locations, thereby improving detection accuracy and efficiency. Experimental validation shows that the enhanced HPRT-DETR model achieves improvements of 6.4, 1.7, and 4.7 percentage points in accuracy, recall, and average precision, respectively, compared to the original model. These results indicate that the enhanced model lays the foundation for automated production and intelligent inspection of metal bipolar plates.

Theoretical investigation of thermal and mass stratification effects on unsteady flow across a vertical oscillating plate with periodic temperature variation and variable mass diffusion

AbstractThis research paper examines the combined effects of thermal and mass stratification on unsteady flow past a vertical oscillating plate with periodic temperature variation and variable mass diffusion. The Laplace transform technique is introduced to deal with the linear coupled parabolic equations satisfying initial as well as boundary conditions and obtained solutions in closed form for concentration, temperature, and velocity. For example, to find the Laplace transform of an exponentially ordered piece wise continuous function , one can uses the formula , t being the time and s is a parameter. In this study, we explore the effects of different factors such as plate amplitude, plate frequency, thermal Grashof number, and the mass Grashof number on the concentration, velocity, and temperature profiles and shows them graphically. We see a decline in the fluid's velocity for thermal and mass stratification. Most interestingly, in presence of higher temperature gradient, as the frequency of the oscillations increases close to the plate surface, the fluid velocity declines. The reason behind this is that the flow system has a plate with very high fluctuations. We have found that the fluid's temperature goes up while the concentration goes down when there is a decrease in the thermal stratification and a rise in the mass stratification.

Concepts for compensation of wave effects when measuring through water surfaces in photogrammetric applications

Abstract. A common problem when imaging and measuring through moving water surfaces is the quasi-random refraction caused by waves. The article presents two strategies to overcome this problem by lowering the complexity down to a planer air/water interface problem. In general, the methods assume that the shape of the water surface changes randomly over time and that the water surface moves around an idle-state (calm planar water surface). Thus, moments at which the surface normal is orientated vertically should occur more frequently than others should. By analysing a sequence of images taken from a stable camera position these moments could be identified – this can be done in the image or object space. It will be shown, that a simple median filtering of grey values in each pixel position can provide a corrected image freed from wave and glint effects. This should have the geometry of an image taken through calm water surface. However, in case of multi camera setups, the problem can be analysed in object space. By tracking homological underwater features, sets of image rays hitting accidently horizontal orientated water surface areas can be identified. Both methods are described in depth and evaluated on real and simulated data.

Multimedia Photogrammetry with non-planar Water Surfaces – Accuracy Analysis on Simulation Basis

Abstract. If multimedia-photogrammetry is used for the generation of point clouds of submerged objects or of the water bottom, Snell’s law has to be considered. When the images are taken from air, image rays are refracted at the air-water interface. This results in the collinearity equations being no longer valid. Bundle block adjustment can still be solved by adding additional terms considering Snell’s law. Existing approaches usually assume that the water surface is flat. Refractive indices and water height can either be measured separately or included as unknowns in the adjustment. However, when the water surface is not flat due to the presence of waves, assuming a planar water surface leads to large geometric errors. This work will analyze the significance of those errors and propose a way of including water surface parameters as unknowns into the bundle block adjustment, both based on simulated data. The simulation reproduces multiple images taken simultaneously, e.g. from synchronized UAV cameras or from cameras on tripods.