Various Conditions Of Temperature Research Articles

Tribological properties of novel Al 7075(T6)-SiC-crumb rubber-MoS2-based hybrid composites: An experimental approach towards green revolution

In the present study, an experimental approach is conducted for analyzing the tribological attributes of the novel green hybrid metal matrix composites fabricated by an advanced vacuum-sealed bottom pouring stir casting comprised of Al 7075(T6) as a base metal doped with three distinct reinforcements as silicon carbide, crumb rubber, and molybdenum disulfide. Six casting process variables such as SiC, crumb rubber, MoS2, stirring speed, stirring time, and pouring temperature have opted for the fabrication of green hybrid composites via Taguchi L18 mixed-level orthogonal array. Tribological studies (in terms of wear loss, frictional force, and coefficient of friction) on fabricated green composites are examined via the high-temperature rotary pin-on-disc tribometer with fixed process parameters (such as wear track diameter, sliding speed, normal load, sliding distance, disc rotation speed, and test duration) under dry sliding wear test. Moreover, the wear test is also executed under variable temperature conditions of 35 °C, 100 °C, 200 °C, and 300 °C. The metallography of synthesized green composites and their worn surfaces is inspected via a metallurgical microscope and scanning electron microscopy–energy dispersive X-ray spectroscopy techniques. Besides, the analysis of variance is implemented to predict the percentage contribution of the combined process variables for wear loss analysis. In contrast to the as-cast specimen (S0), the developed hybrid pin specimen (S3) yields a tremendous improvement in its metallurgical and tribological attributes under varying temperature conditions. Owing to the merits of the proposed composite, it can be extensively used in lightweight, high-temperature, and wear-resistant applications of various automotive and aerospace engineering.

Research on the removal of Cr(VI) ions from wastewater by Mg/Al-layered double oxides

Cr(VI) is a common pollutant in wastewater that poses a threat to human health and wellbeing. Layered double hydroxides (LDHs) have been identified as an effective physical adsorbent due to their strong anion exchange capacity and memory effect. This work found that calcined Mg/Al-LDHs can effectively remove Cr(VI) ions from wastewater. The adsorption capacity of Mg/Al- layered double oxides (LDOs) for Cr(VI) ions was tested under varying temperature conditions, and the results were found to conform to the Langmuir isotherm model. The maximum adsorption capacity of Mg/Al-LDOs for Cr(VI) ions was 147.39 mg/g at 20 °C. The crystal plane spacing and microscopic morphology of Mg/Al-LDHs before and after the adsorption of Cr(VI) ions were analyzed using a X-ray diffractometer, high-resolution transmission electron microscopy and selected area electron diffraction, and their microstructures were analyzed by Fourier transformation infrared absorption spectroscopy and X-ray photoelectron spectroscopy. The results showed that the adsorption of Cr(VI) ions by Mg/Al-LDOs can be divided into two processes at 20 °C. The first process was the recovery of the single-crystal structure of Mg/Al-LDHs by the adsorption of Cr(VI) ions by Mg/Al-LDOs, and the adsorption capacity of Cr(VI) ions in this process was limited due to the restricted layer spacing in the single-crystal structure. The second process was that the recovered Mg/Al-LDHs single-crystal structure continued to adsorb Cr(VI) ions and grew into a nanoflower-like compound with a polycrystalline structure, and this process led to an increase in the layer spacing of Mg/Al-LDHs, greatly increasing the interlayer Cr(VI) ions adsorption capacity. Additionally, the adsorption of Cr(VI) ions by Mg/Al-LDOs was accompanied by the conversion of Cr(VI) ions to Cr(III) ions at 20 °C, and Cr(III) ions could enter the plate structure to form the Mg/Al/Cr-LDHs structure, which further improved the adsorption capacity and efficiency for interlayer Cr(VI) ions.

Effect of Different Fineness of Cement on the Autogenous Shrinkage of Mass Concrete under Variable Temperature Conditions

The internal temperature of the mass concrete is not constant. In the actual project, the internal temperature of the concrete will experience a process of rapid warming to reach the peak temperature and then slow down. In this study, volume measurement method is used to simulate the internal volume deformation of mass concrete under actual engineering conditions. The embedded strain gauge was embedded in concrete with a water-cement ratio of 0.32 for 28 days, and the development of total volume deformation and autogenous volume deformation of concrete under variable temperature conditions was studied by external heating of concrete. The results show that the finer the cement, the earlier the concrete starts to shrink, and the greater the total shrinkage of the concrete. The high temperature will promote the hydration of cement with different fineness and will reduce the total porosity of their paste, but the proportion of harmful pores in the paste with finer cement particles is lower.

Heat transfer of MHD flow over a wedge with a surface of mutable temperature

AbstractThe objective of this study is to investigate the thermal distribution and heat transfer in the boundary layer of a wedge with a variable surface temperature in the presence of a magnetic field. To achieve this, we first used similarity solutions to transform the governing equations of magnetohydrodynamic flow for variable surface temperature conditions into ordinary differential equations. We then solved the resulting equations using the collocation method (CM) with different intensity magnetic fields and varying Hartmann (Ha) numbers and surface temperatures. The CM was further modified by incorporating boundary conditions. The results obtained from the solved equations were validated and compared with those obtained using the numerical Runge–Kutta fourth‐order method and previous literature. Finally, we investigated the impact of various parameters on the friction coefficient (Cf) and Nusselt number (Nu), including the power of variable surface temperature (n), Prandtl (Pr) number, Eckert (Ec) number, the half angle of the wedge (φ), and Ha number. We considered values for these parameters within the ranges 0.5 ≤ n ≤ 1.5, 0.5 ≤ Pr ≤ 5, 0.001 ≤ Ec ≤ 0.002, 15° ≤ φ ≤ 60°, and 0 ≤ Ha ≤ 3. Our findings indicate that the slope of the boundary layer increases with increasing Ha or φ, resulting in an increase in Cf on the surface by up to 526%. The Nu number, calculated using the energy equation, increases up to 91.7%, 39.8%, and 1.43% with increasing Ha, n, and Ec, respectively, resulting in faster growth of the thermal boundary layer, which causes the thickness to decrease and the Nu number to rise. However, as φ increases, the Nu number drops on the surface, and the heat transfer behavior remains similar to that observed previously.

Prediction of PV cell parameters at different temperatures via ML algorithms and comparative performance analysis in Multiphysics environment

As the world moves towards renewable resources to meet the heaping power demand, the dependence on Photo Voltaic (PV) panel-based power generation has globally touched 1000TWh in 2021. These panels made up of different materials, such as Germanium (Ge), Silicon (Si), Indium Phosphide (InP), and Gallium Arsenide (GaAs), work in wider applications ranging from earth to space. But in real-time environmental conditions, these materials exhibit only 11 to 15 % efficiency, mainly due to thermal loss and exposure to variable irradiation and temperature conditions. Thus, in the current research, the PV cell/panel is modeled in an experimentally validated Multiphysics environment at temperatures from – 45 0C to + 51 0C using Ge, Si, InP, and GaAs as materials.The efficiency of the PV cell/panel is estimated in the current research based on the thermal losses within the material, the width of the bandgap, and the thickness of the cell. To analyze the thermal losses, joule heat generation of PV cell/panels made of all different materials is obtained. It is observed that at ambient temperature, although the GaAs and InP have an energy bandgap of 1.42 eV and 1.34 eV, respectively, the joule heating effect is minimum (3.95KW/m3 - InP, 5.05KW/m3- GaAs) when compared to Si (61KW/m3) and Ge (234KW/m3). But InP showed lower efficiency due to the thickness of the cell, which prevents the penetration of photons deeper into the inner layers. Further, in this research, the effect of real-time temperature conditions is obtained for all the PV panels by modeling them at −45 °C, 0 °C, 25 °C, and 51 °C. Parameters such as short circuit current (Isc), open circuit voltage (Voc), Fill Factor (FF), and maximum power (Pmax) are enumerated along with the efficiency. For a faster parametric analysis at all possible real-time temperature conditions in Indian climatic scenario, in this research, an ML based prediction model is developed using Kernel Ridge Regression (KRR), Polynomial Regression (PR), Linear Regression (LR), and Support Vector Regression (SVR). It is observed that, the KRR algorithm can give faster (in few seconds), effective, and error-free prediction (92.23% of accuracy). The prediction results are validated with the Multiphysics environment, data sheet, and experimental data.

Effect of CO<sub>2</sub> Additives on the Non-Catalytic Conversion of Natural Gas into Syngas and Hydrogen

Abstract—A kinetic analysis of the non-catalytic carbon dioxide reforming of CH4 has been carried out in the temperature range of 1500–1800 K under conditions of variable temperature behind the reflected shock wave. The stages of conversion of methane into synthesis gas, the characteristic time intervals corresponding to these stages, and the most important elementary reactions have been established. At the first stage, as a result of thermal pyrolysis, methane molecules are sequentially converted into ethane, ethylene, and then acetylene, the most stable hydrocarbon in this temperature range. At the second stage, acetylene is normally converted into CO and H2, being accompanied by the formation soot particles in the case of rich mixtures. The conversion of CO2 proceeds at the second and third stages, when CH4 conversion is almost complete. It occurs as a result of the interaction of CO2 molecules with H● atoms arising in the reacting system and leads to the formation of CO molecules and OH● radicals. Acetylene is predominantly consumed in the reaction with OH radicals. A high concentration of acetylene during methane reforming promotes the intensive formation of soot nuclei, for which acetylene makes the highest contribution to the rate of their surface growth. At the same time, acetylene itself is not a precursor of soot particle nuclei, which are mainly formed from \({{{\text{C}}}_{{\text{3}}}}{\text{H}}_{3}^{\centerdot }\) radicals.

Experimental study of the dielectric properties of energy-containing materials at variable temperatures.

Due to the inherent material characteristics of fireworks and negligent safety management, safety accidents have occurred in recent years, resulting in significant personal and property losses. Therefore, the status inspection of fireworks and other energy-containing materials is a hot issue in the field of energy-containing materials production, storage, transportation, and application. The dielectric constant is a parameter used to characterize the interaction between materials and electromagnetic waves. The methods of obtaining this parameter in the microwave band are not only numerous but also fast and easy. Thus, the real-time status of energy-containing materials can be monitored by monitoring their dielectric properties. Usually, temperature variation has an important effect on the state of energy-containing materials, and the accumulation of temperature can directly cause energy-containing materials to burn or even explode. Based on the above background, this paper proposes a method for testing the dielectric properties of energy-containing materials under variable temperature conditions based on the resonant cavity perturbation theory, which provides important theoretical support for testing the state of energy-containing materials under variable temperatures. Based on the constructed test system, the law of the variation of the dielectric constant of black powder with temperature was obtained, and the theoretical analysis of the test results was carried out. Experimental results show that the temperature change will induce chemical changes in the black powder material, specifically in its dielectric properties, and the magnitude of the changes is large, which is very conducive to real-time monitoring of the black powder state. The system and method developed in this paper can be used to obtain the high-temperature evolution of the dielectric properties of other types of energy-containing materials and provide technical support for the safe production, storage, and application of various types of energy-containing materials.

Preparation of a thermosensitive nanofibre membrane for blackberry preservation

Blackberries provide multiple health benefits. However, they deteriorate easily during harvesting, storage, and transportation (temperature-changing). Therefore, to extend their shelf-life under variable temperature conditions, a temperature-sensitive nanofibre-based material with good preservation attributes was developed, composed of polylactic acid (PLA) electrospun fibres, loaded with lemon essential oil (LEO) and covered with poly (N-isopropylacrylamide) (PNIPAAm). Compared with PLA and PLA/LEO nanofibres, PLA/LEO/PNIPAAm exhibited good mechanical properties, oxidation resistance, antibacterial ability, and controlled release of LEO. The PNIPAAm layer prevented rapid LEO release below the low critical solution temperature (32 °C). When the temperature exceeded 32 °C, the PNIPAAm layer underwent a chain-to-globule transition and accelerated LEO release (slower than PLA/LEO). The temperature-controlled release of LEO via PLA/LEO/PNIPAAm membrane prolongs its action time. Therefore, PLA/LEO/PNIPAAm effectively maintained the appearance and nutritive quality of blackberries during variable storage temperatures. Our research demonstrated that active fibre membranes have great potential applications in preserving fresh products.

Effect of Different Expansive Agents on the Deformation Properties of Core Concrete in a Steel Tube with a Harsh Temperature History

The shrinkage of core concrete during construction is the key reason for the separation of steel pipes and core concrete. Utilizing expansive agents during cement hydration is one of the main techniques to prevent voids between steel pipes and core concrete and increase the structural stability of concrete-filled steel tubes. The expansion and hydration properties of CaO, MgO, and CaO + MgO composite expansive agents in C60 concrete under variable temperature conditions were investigated. The effects of the calcium-magnesium ratio and magnesium oxide activity on deformation are the main parameters to consider when designing composite expansive agents. The results showed that the expansion effect of CaO expansive agents was predominant in the heating stage (from 20.0 °C to 72.0 °C at 3 °C/h), while there was no expansion in the cooling stage (from 72.0 °C to 30.0 °C at 3 °C/d, and then to 20.0 °C at 0.7 °C/h); the expansion deformation in the cooling stage was mainly caused by the MgO expansive agent. With the increase in the active reaction time of MgO, the hydration of MgO in the heating stage of concrete decreased, and the expansion of MgO in the cooling stage increased. During the cooling stage, 120 s MgO and 220 s MgO resulted in continuous expansion, and the expansion curve did not converge, while 65 s MgO reacted with water to form brucite in large amounts, leading to its lower expansion deformation during the later cooling process. In summary, the CaO and 220 s MgO composite expansive agent in the appropriate dosage is suitable for compensating for the shrinkage of concrete in the case of a fast high-temperature rise and slow cooling rate. This work will guide the application of different types of CaO-MgO composite expansive agents in concrete-filled steel tube structures under harsh environmental conditions.

Experimental Study of Complex Resistivity Characteristics of a Sandstone Reservoir under Different Measurement Conditions

Due to the variability of fluid properties and saturation of reservoirs, large differences in formation temperature and pressure, and the diversity of rock and mineral compositions, the petrophysical response of reservoirs is often complex. This study explored a new method of reservoir fluid identification and evaluation based on the complex resistivity response characteristics of sandstone reservoirs under different measurement conditions. The complex resistivity of the five sandstone samples was measured under normal temperature and pressure and variable pressure, temperature, and formation conditions and under different oil saturations. Furthermore, the reservoir was comprehensively analyzed and evaluated based on the mineral composition, porosity, and permeability parameters. The results show that the resistivity of the sandstone increases logarithmically with pressure and oil saturation but decreases logarithmically with temperature and depth. The polarizability decreases slightly with increasing pressure and increases slightly with increasing temperature. With increasing depth, the polarizability decreases obviously, and with increasing oil saturation, the polarizability decreases moderately. Under different measurement conditions, the complex resistivity data for the sandstone reservoir and the IP parameters extracted through inversion are regular. The results of this study provide a new method for the identification and evaluation of complex reservoir fluids and have important reference value.

Straw amendment and nitrification inhibitor controlling N losses and immobilization in a soil cooling-warming experiment

It is common practice in agriculture to apply high‑carbon amendments, e.g. straw, or nitrification inhibitors (NI) to reduce soil nitrogen (N) losses. However, little is known on the combined effects of straw and NI and how seasonal soil temperature variations further affect N immobilization. We conducted a 113-day mesocosm experiment with different levels of 15N-fertilizer application (N0: control; N1: 125 kg N ha−1; N2: 250 kg N ha−1) in an agricultural soil, amended with either wheat straw, NI or a combination of both in order to investigate N retention and loss from soil after a cooling-warming phase simulating a seasonal temperature shift, i.e., 30 days cooling phase at 7 °C and 10 days warming phase at 21 °C. Subsequently, soils were planted with barley as phytometers to study 15N-transfer to a following crop.Straw addition significantly reduced soil N-losses due to microbial N immobilization. Although carbon added as straw led to increased N2O emissions at high N fertilization, this was partly counterbalanced by NI. Soil cooling-warming strongly increased ammonification (+77 %), while nitrification was suppressed, and straw-induced microbial N immobilization dominated. N immobilized after straw addition was mineralized at the end of the experiment as indicated by structural equation models. Re-mineralization in N2 was sufficient, but still suboptimal in N0 and N1 at critical times of early barley growth. N-use efficiency of the 15N tracer decreased with fertilization intensity from 50 % in N1 to 35 % in N2, and straw amendment reduced NUE to 25 % at both fertilization rates. Straw amendment was most powerful in reducing N-losses (−41 %), in particular under variable soil temperature conditions, but NI enforced its effects by reducing N2O emission (−40 %) in N2 treatment. Sufficient N-fertilization coupled with straw application is required to adjust the timely re-mineralization of N for subsequent crops.

Study of magnetic properties of electrical steels with different Si content considering the effect of temperature

Electrical steel cores in electric motors are often operated under variable temperature conditions, and the temperature has a large impact on the magnetic properties of electrical steel. Different Silicon content also makes electrical steel have different performance characteristics. Therefore, in this paper, an environmentally adjustable electrical steel magnetic property testing system is built to investigate the magnetic property variation of non-oriented electrical steel sheets with different Si contents at different temperatures. Through the experiments in this paper, it is found that the trend of magnetic properties of electrical steels tends to flatten out with increasing Si content under the influence of temperature. In particular, the loss of 6.5% Si shows a trend of first decreasing and then increasing with the increase of temperature. The internal grain structure of electrical steel can explain this phenomenon very well. The larger the grain size, the less the magnetic properties of electrical steel are affected by temperature. In order to further analyze the variation phenomenon of electrical steel loss, the loss separation calculation was carried out for 5 more electrical steels with different Si content in this paper. The reason for this phenomenon was finally explained by a special preparation process of 6.5% Si.

A new technique for monitoring plant transpiration under field conditions using leaf optical dendrometry

Monitoring plant transpiration (Ec) is important for quantifying irrigation amounts and maintaining optimum soil moisture conditions for maximum growth potential. However, real-time quantification of Ec dynamics under field conditions is still challenging due to technical limitations. Here, we present a new approach for monitoring plant water use using continuous measurement of stem water potential dynamics (Ψstem) under non-limiting water conditions. According to Darcy's law, if daytime root to stem hydraulic conductance (Kr-s) remains constant and the contribution of plant capacitance to Ec is minimal or accounted for, then daytime Ec could potentially be continuously inferred from Ψstem dynamics. We investigated the viability of this approach by first quantifying the dynamics of daytime Kr-s and the transient buffering effects of plant capacitance in irrigated plants of two crop species with contrasting physiology and life history: the perennial herbaceous Tanacetum cinerariifolium and the annual monocot Triticum aestivum. Daytime Kr-s dynamics and the effects of plant capacitance were determined by continuously and simultaneously measuring Ψstem with optical dendrometers and Ec with gravimetric method under naturally variable conditions of light, temperature and humidity. Kr-s remained relatively stable throughout the day and the effects of plant capacitance were negligible in both species under field conditions implying that the dynamics of Ec can be inferred from Ψstem. This was clearly supported by the close agreement between measured Ec and that predicted from the optically derived Ψstem. We conclude that optical dendrometry has the potential to continuously monitor both Ec and plant hydration status at high accuracy and temporal resolution under naturally variable atmospheric conditions and optimum water supply. Combining these two aspects of the optically derived Ψstem should create new opportunities to monitor crop water use and maintain plant hydration at optimum levels for maximum productivity in various crops under field conditions.

A reduction in temperature induces bioactive red pigment production in a psychrotolerant Penicillium sp. GEU_37 isolated from Himalayan soil

Filamentous fungi are being globally explored for the production of industrially important bioactive compounds including pigments. In the present study, a cold and pH tolerant fungus strain Penicillium sp (GEU_37), isolated from the soil of Indian Himalaya, is characterized for the production of natural pigments as influenced by varying temperature conditions. The fungal strain produces a higher sporulation, exudation, and red diffusible pigment in Potato Dextrose (PD) at 15 °C as compared to 25 °C. In PD broth, a yellow pigment was observed at 25 °C. While measuring the effect of temperature and pH on red pigment production by GEU_37, 15 °C and pH 5, respectively, were observed to be the optimum conditions. Similarly, the effect of exogenous carbon and nitrogen sources and mineral salts on pigment production by GEU_37 was assessed in PD broth. However, no significant enhancement in pigmentation was observed. Chloroform extracted pigment was separated using thin layer chromatography (TLC) and column chromatography. The two separated fractions i.e., fractions I and II with Rf values 0.82 and 0.73, exhibited maximum light absorption, λmax, at 360 nm and 510 nm, respectively. Characterization of pigments using GC–MS showed the presence of the compounds such as phenol, 2,4-bis (1,1-dimethylethyl) and eicosene from fraction I and derivatives of coumarine, friedooleanan, and stigmasterole in fraction II. However, LC-MS analysis detected the presence of derivatives of compound carotenoids from fraction II as well as derivative of chromenone and hydroxyquinoline as major compounds from both the fractions along with other numerous important bioactive compounds. The production of such bioactive pigments under low temperature conditions suggest their strategic role in ecological resilience by the fungal strain and may have biotechnological applications.

Influence of Heating–Cooling Regime on the Engineering Properties of Structural Concrete Subjected to Elevated Temperature

Structural concrete has become a highly preferable building material in the construction industry due to its versatile characteristics, such as workability, strength, and durability. When concrete structures are exposed to fire, the mechanical properties of concrete degrade significantly. The research on the residual mechanical properties of concrete after exposure is necessary, particularly for the repair and rehabilitation of concrete elements and for the stability of the infrastructure. Factors, such as the grade of concrete, the effect of temperature exposure, and rapid water cooling, affect the residual strength characteristics of concrete. Considering these factors, the present investigation evaluates the mechanical properties of concrete using different grades, such as those ranging from 20 to 50 MPa, with an increment of 10 MPa. The specimens were exposed to different durations of fire from 15 to 240 min, following the standard rate of heating. A loss of strength was observed after fire exposure for all the grades of concrete. The rate of reduction in tensile and flexural strengths of the concrete was greater than that of compressive strength. The experimental results also showed that the strength reduction is greater for M50 than M20 concrete concerning the duration of heating. A microstructure evaluation confirmed the extent of damage to concrete under varied temperature conditions.

Noninvasive liquid level sensing with laser generated ultrasonic waves

This article proposes a noninvasive liquid level sensing technique using laser-generated ultrasound waves for nuclear power plant applications. Liquid level sensors play an important role of managing the coolant system safely and stably in the plant structure. Current sensing techniques are mostly intrusive, performing inside the fluidic structure, which is disadvantageous in terms of the regular maintenance of the plant system. Furthermore, typical intrusive sensors do not perform stably under varying environmental conditions such as temperature and radiation. In this study, sensing units are attached to the outer surface of a liquid vessel to capture guided ultrasound waves in a nonintrusive manner. The signal intensity of the guided wave dissipates when the signal interacts with the internal liquid media. The sensing mechanism is mathematically expressed as an index value to correlate the liquid level with the sensor signal. For the acoustic wave generation, laser-generated ultrasound was adopted instead of using typical contact type transducers. Following the simulation validation of the proposed concept, the performance of the developed sensor was confirmed through experimental results under elevated liquid temperature conditions. The nonlinear multivariable regression exhibited the best-fit to the datasets measured under the variable liquid level and temperature conditions.

Analysis of the Resistance Change of Chemosensitive Layers to the Presence of Ammonia Vapors under Variable Conditions of Air Temperature and Humidity

The developed chemosensitive layers consisted of multi-walled carbon nanotubes (MWCNTs), reduced graphene oxide (rGO), and a conductive polymer (polyaniline-PANI) in a polymeric matrix (a polystyrene solution in methylene chloride). The layers were challenged with a test gas to determine the optimum variant in terms of sensitivity to the selected analyte and the repeatability of results. In terms of individual components, the greatest percentage change in resistance (32%) and the best repeatability were found for chemosensitive layers containing a PANI salt in the polymeric matrix. Even greater changes in resistance were exhibited by sensors containing more than one active component in the matrix: 45% for PANI + MWCNTs and 75% for PANI + rGO. The presented method of thin-layer deposition was shown to be suitable for the production of sensitive and functional sensors of ammonia vapors. The developed sensors were characterized by high repeatability and sensitivity to a harmful substance that constitutes an inhalation hazard to workers. The sensors were also analyzed for their durability and recovery as well as the ability to function under varying temperature and humidity conditions.

THERMO-MECHANICAL SIMILARITY IN THE EXPERIMENTAL AND THEORETICAL MODELING OF THE THERMAL RESISTANCE OF ROAD MATERIALS AND STRUCTURES

Experimental or theoretical modeling of the thermal strength of road materials and structures is usually associated with replacing the study of the effect we are interested in nature (prototype) with the analysis of the solutions of the corresponding mathematical equations or with the consideration of a similar phenomenon on a smaller or larger scale experimental model in special laboratory or experimental conditions with full or partial observance of the correspondence between the physical properties of the objects of nature and the model. The main content of modeling is that, based on the results of mathematical or experimental experiments, it is possible to draw conclusions about the behavior of the system in natural conditions. As a rule, modeling is based on consideration of geometrically or physically similar deformation phenomena of structures. At the same time, it is considered that two bodies are geometrically similar, if the ratio of all corresponding lengths is the same, that is, equal to the coefficient of similarity or scale. Two phenomena are physically similar if the given characteristics of one of them can be used to determine the characteristics of the other with the transition from one system of units to another. As a result of establishing a system of parameters defining a selected class of phenomena, conditions for the similarity of two phenomena can be established. The task of determining similarity conditions for road materials and structures becomes more complicated when they are operated in conditions of variable temperatures, and the number of parameters for which it is necessary to calculate scale factors increases. In this work, they are determined on the basis of the theory of thermoelasticity for geometric characteristics, elasticity parameters (Young's modulus, Poisson's ratio), thermal parameters (linear thermal expansion coefficient, thermal conductivity coefficient). Similarity conditions are defined for the thermal displacement, thermal stress, and temperature functions. Concrete examples also show that methods of similarity theory can be a tool for solving applied problems.

Fluorescent naphthalimide boronates as theranostics: structural investigations, confocal fluorescence and multiphoton fluorescence lifetime imaging microscopy in living cells.

New design and synthetic strategies were developed to generate functional phenyl boronic acid (BA)-based fluorescent probes incorporating the 1,8-naphthalimide (NI) tag. This fluorescent core was anchored onto the BA unit through small organic linkers consisting of nitrogen groups which can arrest, and internally stabilise the phenyl-boronate units. The newly synthesised fluorophores were characterised spectroscopically by NMR spectroscopy and mass spectrometry and evaluated for their ability to bind to a naturally occurring polysaccharide, β-d-glucan in DMSO and simultaneously as act as in vitro cell imaging reagents. The uptake of these new NI-boronic acid derivatives was studied living cancer cells (HeLa, PC-3) in the presence, and absence, of β-d-glucan. Time-correlated single-photon counting (TCSPC) of DMSO solutions and two-photon fluorescence-lifetime imaging microscopy (FLIM) techniques allowed an insight into the probes' interaction with their environment. Their cellular uptake and distributions were imaged using laser scanning confocal fluorescence microscopy under single- and two-photon excitation regimes (λmax 910 nm). FLIM facilitated the estimation of the impact of the probe's cellular surroundings using the fluorophore lifetime. The extent to which this was mediated by the β-d-glucan was visualised by 2-photon FLIM in living cells. The fluorescence lifetime observed under a range of temperatures varied appreciably, indicating that changes in the environment can be sensed by these probes. In all cases, the cellular membrane penetration of these new probes was remarkable even under variable temperature conditions and localisation was widely concentrated in the cellular cytoplasm, without specific organelle trapping: we conclude that these new probes show promise for cellular imaging in living cancer cells.

Pressure vessel leakage detection method based on online acoustic emission signals

Pressure vessel leakages cannot initially be visited directly and will gradually cause deterioration, which can result in catastrophic damage. Acoustic emission (AE) signals generated by leakage have the potential of being used for online monitoring. Unfortunately, AE signals have the characteristics of being non-stationary, wide-band and with strong noise interference, which causes the monitoring results to have low reliability. To address the poor robustness of traditional time-domain and time-frequency domain-based monitoring methods, an online monitoring method based on adaptive singular value decomposition (ASVD) is proposed in this paper. Firstly, singular value decomposition (SVD) is used to divide the signal space into a signal subspace and a noise subspace. Experiments indicate that SVD can distinguish leakages under conditions of different pressures and variable temperature, which means that SVD is sensitive to changes in signal. Subsequently, update iteration-based ASVD algorithms are proposed for long-term online health monitoring and ASVD is shown to be successful in distinguishing the different statuses of intact, leakage and repaired. To improve the robustness of ASVD, a novel energy indicator is proposed, which can identify the status change more effectively. With the proposed methodology, an online monitoring application for pressure vessel leakage detection is expected to be achievable.