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The accidental spilling of cryogenic liquid leads to formation of a spreading pool, which may result in pool fires, BLEVE(boiled liquid evaporate vapor explosion) or vapor cloud fire, such as liquefied natural gas, is flammable. The key aspect of evaluating the consequence of such a disaster is to predict vaporization rate of the spreading cryogenic liquid pool. In this study, an empirical function was established to predict the temperature gradient of concrete. Afterwards an improved 1-D heat conduction equation was established to predict heat conduction of the spreading cryogenic liquid, and then vaporization rate was measured. In addition, to validate accuracy of the improved 1-D heat conduction equation, small-scale experiments were conducted to calculate vaporization rate for a spreading cryogenic liquid pool. The resulting vaporization rate decreased with discharge time, and increased with spill rate. The established empirical function was used to predict the temperature gradient displayed satisfactory accuracy with absolute average relative errors (AAREs) less than 10%; the improved 1-D heat transfer model AAREs were less than 13% compared with the experimental value. In summary, the improved 1-D heat transfer model can be applied to predict vaporization rate if the spill rate and discharge time are confirmed. [ABSTRACT FROM AUTHOR]

Directed energy deposition with laser beam (DED-LB) components experience significant residual stress due to rapid heating and cooling cycles. Excessive residual tensile stress can lead to cracking in the deposited sample, resulting in service failure. This study utilized digital image correlation (DIC) and thermal imaging to observe the in situ temporal evolution of strain and temperature gradients across all layers of a deposited 316 L stainless steel thin wall during DED-LB. Both continuous-wave (CW) and pulsed-wave (PW) laser modes were employed. Additionally, the characteristics of thermal cracks and geometric dislocation density were examined. The results reveal that PW mode generates a lower temperature gradient, which in turn reduces thermal strain. In CW mode, the temperature–stress relationship curve of the additive manufacturing sample enters the "brittleness temperature zone", leading to the formation of numerous hot cracks. In contrast, PW mode samples are almost free of cracks, as the metal avoids crack-sensitive regions during solidification, thereby minimizing hot crack formation. Overall, these factors collectively contribute to reduced residual stress and improved mechanical properties through the adjustment of pulsed-wave laser deposition. [ABSTRACT FROM AUTHOR]

In order to investigate the temperature rise mechanism of laser cladding assisted by ultrasonic energy field, the multi-field heat flow behavior of laser cladding with or without ultrasonic field assistance is studied.Based on the theoretical analysis of laser-powder interaction and thermal effect of ultrasonic energy field, the coupling equation of laser effective heat input and ultrasonic effective heat conversion is obtained.A numerical model of three-dimensional phase-change heat transfer in laser cladding assisted by ultrasonic energy field is established. The solid–liquid phase change and dynamic evolution of the cladding layer are treated by the apparent heat capacity method and the deformation geometry method respectively. The variations of transient heat and velocity with distance based on laser spot center with or without ultrasonic energy field are studied. The effect of ultrasonic energy field on multi-field coupling of heat flow in laser cladding layer is discussed.Then ultrasonic field-assisted laser cladding IN718 experiment is conducted. The surface temperature of the melt pool is tracked in real time. The evolution law of the microstructure of the cladding layer and the distribution of alloying elements are analyzed.The reliability of the model is verified by analyzing the experimental results.The results show that when the laser cladding time is 2 s, the peak temperature and velocity of the molten pool reach the maximum value, which are 2483 K and 0.316 m/s respectively.Under the action of ultrasonic field, when the cladding time is 1 s, 2 s, 3 s and 3.5 s, the peak temperature of the molten pool increases by 26 K, 38 K, 105 K and 121 K respectively. The velocity of the molten pool reaches the maximum when the ultrasonic field acts for 2 s, which reaches 0.319 m/s.With the continuous application of ultrasonic field, the temperature gradient(G) of the cladding layer decreases gradually, and the solidification rate(R) and cooling rate increase. The ratio of temperature gradient to solidification rate (G/R) decreased.In the test range, the temperature variation of the molten pool surface is basically consistent with the simulation results.Ultrasonic field can promote the transformation of microstructure of IN718 cladding layer from columnar dendrites to equiaxial dendrites. The average minimum grain size of the top, middle and bottom of the cladding layer is reduced by 53.70%, 21.8% and 40.82% respectively. The element distribution of the cladding layer is also more uniform. [ABSTRACT FROM AUTHOR]

A thorough understanding of the reactor core thermal hydraulic behavior is essential for the design and safety analysis of Sodium-cooled Fast Reactors (SFR). Due to the application of hexagonal subassembly, the core thermal hydraulic behavior is significantly affected by the flow field within the subassemblies, the inter-wrapper region and the hot pool. Analysis of the core thermal hydraulic behavior requires a model coupling the three regions mentioned above, which has been identified as one of the thermal hydraulic challenges in SFR. In the present study, a 3D model that covers the three regions was developed for the core of the China Experimental Fast Reactor (CEFR) with the Computational Fluid Dynamic (CFD) code, Fluent. The inter-wrapper region and the hot pool were modeled in detail, while the subassemblies were modeled with a special porous medium model. The core thermal hydraulics behavior under steady state was studied, more specifically, information for the flow field distribution at the core outlet, the inter-wrapper flow and the duct wall temperature distribution was obtained. Under steady state, liquid sodium in the inter-wrapper region is supplied by the inner region of the hot pool. And it enters the inter-wrapper region from the core outer region and returns back to the hot pool inner region from the core central region. The inter-wrapper flow is cooled by non-fuel subassemblies and heated up by fuel subassemblies. For non-fuel subassembly, the ratio of the total heat transfer rate between the inter-wrapper flow and the subassemblies to the heat generated within subassemblies could reaches 96%; for fuel subassemblies, the maximum ratio of the total heat transfer rate between the inter-wrapper flow and the subassemblies to the heat generated within subassemblies is 2.45%. Significant temperature gradients have been observed on the duct wall, with maximum values of 156.69 K/m in the vertical direction and 2,196.00 K/m in the circumferential direction. The largest temperature gradient appears on the duct of subassemblies adjacent to the transition region of fuel subassemblies and non-fuel subassemblies. [ABSTRACT FROM AUTHOR]

The traditional passive heat dissipation method has low heat dissipation efficiency, which is not suitable for the heat dissipation of the concentrated heat source inside the long-focal aerial camera, resulting in temperature level changes and temperature gradients in the optical system near the heat source, which seriously affect the imaging performance of the aerial camera. To solve this problem, an active heat dissipation method of liquid cooling cycle is proposed in this paper. To improve the solving efficiency and ensure simulation accuracy, a dynamic boundary information transfer method based on grid area weighting is proposed. The thermal simulation results show that the liquid cooling method reduces the heat source temperature by 70.12%, and the boundary temperature transfer error is 0.015%. The accuracy of thermal simulation is verified by thermal test, and the simulation error is less than 6.44%. In addition, the performance of the optical system is further analyzed, and the results show that the MTF of the optical system is increased from 0.077 to 0.194 under the proposed active liquid cooling cycle heat dissipation method. [ABSTRACT FROM AUTHOR]

The high-temperature and high-humidity conditions arising from the biochemical degradation of landfill waste result in significant temperature gradients within the landfill cover. The effects of waste temperature on landfill gas transport and microbial aerobic methane oxidation are not fully understood. In this study, a fully coupled theoretical model was developed to simulate the interactions of moisture, heat, and gas transport within a capillary barrier cover. A series of parametric studies were carried out to investigate the influence of the combined effects of temperature gradient, initial soil moisture content, and landfill gas generation rate on methane transport, oxidation, and emissions. The simulated results indicated that increasing waste temperature intensified the temperature gradient, leading to higher surface evaporation rates and variations in methane oxidation efficiencies. Additionally, variations in initial soil moisture content and landfill gas generation rates were found to significantly impact gas migration and methane oxidation in the cover. This study demonstrates the critical role of waste temperature in landfill gas migration within landfill cover systems, providing technical methodologies for the optimized design of soil cover systems. [ABSTRACT FROM AUTHOR]

Yttrium‐stabilized zirconia (YSZ) plays a crucial role in thermal barrier coatings widely used to protect metallic components in gas turbine engines against high‐temperature combustion product gases and harsh environments. The thermal conductivity of these coatings is a critical parameter influencing the gas turbine design, performance, and service life. In this study, a laser temperature gradient method is utilized to measure the thermal conductivity of porous YSZ coatings. The method employs specialized laser energy delivery to create a one‐dimensional temperature gradient through the sample thickness, closely simulating the operational condition. This approach provides an effective, direct means to determine the thermal conductivity of high‐temperature heat‐resistant porous ceramic materials. [ABSTRACT FROM AUTHOR]

In most chemical and high-temperature processes, metals are exposed to temperature gradients which, in turn, affect the extent of corrosion phenomena. In this study, a long, continuous strip of alloy 625 was exposed to lithium fluoride in a temperature range of 50–600 °C, air environment. The hottest section of this strip was analyzed as a coupon and compared with two other coupons which were exposed isothermally. One of the isothermal exposures was carried out in a tube furnace, and the other one was in a vertical furnace. Oxygen had three different kinds of access to these three coupons, which, in turn, affected the corrosion process. In order to limit the access of oxygen, a long column of lithium fluoride was used in a vertical furnace. The results of the isothermal exposure showed that more access of oxygen in a horizontal tube furnace facilitated the fluoride ingress to a great extent. However, a long sample exposed to a temperature gradient suffered more corrosion attack than the isothermal coupon, under the same LiF load in the vertical furnace. This was associated with the reduction of oxygen at a larger cathode area reaching into colder regions in Inconel 625 strip. Increased oxygen reduction also increases the efficiency of an inner anode at the hottest section, causing the observed rapid intergranular fluoride uptake. The study proposes a mechanism explaining these observations. [ABSTRACT FROM AUTHOR]

The oxidation resistance of yttria‐stabilized zirconia (YSZ) thermal barrier coatings and conductivity of YSZ solid oxide fuel cells are closely related to the diffusion of oxygen ions (O2−$\text{O}^{2-}$) in YSZ, but the O2−$\text{O}^{2-}$ diffusion behavior in small‐sized YSZ samples under non‐isothermal condition where the temperature gradient (∇T$\nabla T$) could be significant remaining elusive. Herein, we disclose the previously unrevealed effect of extreme ∇T$\nabla T$ on the self‐diffusion behavior of O2−$\text{O}^{2-}$ in both pristine and strained YSZ. It is found that the O2−$\text{O}^{2-}$ self‐diffusion coefficient (D$D$) experiences a nearly one‐fold increase under an extreme ∇T$\nabla T$ around 60 K/Å. The diffusion direction tends to be toward regions of high temperature. Uniaxial stress is revealed to reduce D$D$ due to the increased activation energy of ions, whereas ∇T$\nabla T$ promotes the O2−${\text{O}}^{2-}$ self‐diffusion in the stressed system. These results underscore the role of ∇T$\nabla T$ in influencing the self‐diffusion behavior of YSZ, providing a theoretical guideline for examining ceramics serving in extreme environments. [ABSTRACT FROM AUTHOR]

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Abstract. Using herbarium specimens spanning 133 years and field-collected measurements, we assessed intraspecific trait (leaf structural and stomatal) variability from grass species in the Great Plains of North America. We focused on two widespread, closely related grasses from the tribe Paniceae: Dichanthelium oligosanthes subsp. scribnerianum (C3) and Panicum virgatum (C4). Thirty-one specimens per taxon were sampled from local herbaria from the years 1887 to 2013 to assess trait responses across time to changes in atmospheric [CO2] and growing season precipitation and temperature. In 2021 and 2022, the species were measured from eight grasslands sites to explore how traits vary spatially across natural continental precipitation and temperature gradients. Δ13C increased with atmospheric [CO2] for D. oligosanthes but decreased for P. virgatum , likely linked to increases in precipitation in the study region over the past century. Notably, this is the first record of decreasing Δ13C over time for a C4 species illustrating 13C linkages to climate. As atmospheric [CO2] increased, C:N increased and δ15N decreased for both species and %N decreased for D. oligosanthes. Across a large precipitation gradient, D. oligosanthes leaf traits were more responsive to changes in precipitation than those of P. virgatum. In contrast, only two traits of P. virgatum responded to increases in temperature across a gradient: specific leaf area (increase) and leaf dry matter content (decrease). The only shared significant trend between species was increased C:N with precipitation. Our work demonstrates that these closely related grass species with different photosynthetic pathways exhibited various trait responses across temporal and spatial scales, illustrating the key role of scale of inquiry for forecasting leaf trait responses to future environmental change. [ABSTRACT FROM AUTHOR]

This research study investigates the impact of various parameters such as L/D ratio, cold mass proportion, inlet pressure, and nozzle count on the performance and thermal energy separation process of a counter flow Ranque-Hilsch vortex tube (VT). Experimental and numerical methods were employed to assess the cold and hot exit temperatures, as well as the thermal energy separation. Four different orifice plates with two, three, five, and six nozzles were used in the experimentation, while air inlet pressure and cold mass fractions were varied between 200–1000 kPa and 0.5–0.7, respectively. The numerical model developed in ANSYS utilized the standard k-ε turbulence model to evaluate velocity and temperature patterns for optimal performance parameters. The results demonstrated that inlet pressure had the greatest influence on VT performance, and higher angular velocity differences were induced between the center and circumferential area of the VT. The study concludes by highlighting the minimum cold exit temperature of − 12 °C and the maximum hot exit temperature of 64.5 °C, as well as providing a useful framework for researchers to assess the thermal energy separation process across different Ranque-Hilsch VTs with varying orifice plates and nozzles. [ABSTRACT FROM AUTHOR]

A curved heat transfer surface is proposed to improve the condensation process. The flow performance and condensation law in the cosine-shaped flow channel, a special curved surface, are numerically and theoretically studied. A theoretical model of surface filmwise condensation on a curved flow channel is established and the mathematical model is validated. The liquid film thickness equation in different zones of the curved surface is deduced and calculated. The results show that the main condensation heat transfer zone is in the middle zone (25 mm < s < 45 mm) and the wave crest zone (0 mm ≤ s ≤ 25 mm), the temperature gradient of the liquid film surface decreases along the liquid flow direction, and the liquid film thickness becomes thinner with the increase of steam velocity. [ABSTRACT FROM AUTHOR]

The localised heat addition and rapid temperature fluctuations during welding induces significant levels of residual stresses in thick-walled pipe welds. Residual stress so induced by welding, need to be stress relieved; in these thick walled pipes that are extensively used in power plant applications. While thermal stress relieving (SR) serves as a pivotal intervention, field-welded components and sizable weldments, exceeding furnace capacities, necessitate resistance-based, local post weld heat treatment (PWHT). Nevertheless, the local heating of pipes always results in a finite Through-Thickness Temperature Gradient (TTG). Though, heat treatment parameters are governed by standards, to limit TTG for effective SR; observations indicate limitations of these parameters in achieving desired TTG for specific pipe dimensions. Prior studies specify two alternatives viz. widening the heated band and reducing the heating rate to achieve the desired TTG. However, the preferred approach of widening the heat band for larger pipes; necessitate exorbitantly large capacity power sources and expose a wider zone of weldment to critical transformation temperatures which pose practical limitations and attract industrial apprehensions. Thus, to take informed decisions, the relative efficacies of alternatives over the standard governed approach in terms of relief and redistribution of residual stress, capacity of power source required and energy consumed are evaluated through Finite Element (FE) simulation. Valuable insights from FE results, considering the merits, demerits, logical advantages and financial implications facilitating selection of appropriate SR strategy in industrial applications for successfully relieving stress in difficult to SR pipes (thick-walled, SA335P91) are determined and discussed in detail. [ABSTRACT FROM AUTHOR]

Ground round bars made of WC-20 mass%Co cemented carbides were used to accurately determine the changes in shape. The bars were heated at 1673 K and cooled under different conditions to investigate the changes in Co content and diameter (d) in the longitudinal direction. When the bars were heated in a conventional sintering furnace, rapid cooling increased the Co content and d at both ends, while slow cooling increased those at the center. In the latter case, the amount of change was smaller. When the bar was heated using a tubular furnace and then cooled under 30 K of temperature gradient in the longitudinal direction, the Co content and d on the higher temperature side decreased and those on lower temperature side increased. The relationship between the change in Co content and the change in d could be explained quantitatively by considering the migration of the liquid phase in the temperature range of solid-liquid Co coexistence region. This study revealed that when WC-Co cemented carbides were fabricated using the conventional sintering furnace, an inevitable temperature gradient in the specimen during cooing caused the liquid phase migration and the shape distortion, regardless of the cooling rate. [ABSTRACT FROM AUTHOR]

In areas with large temperature differences, the uneven distribution of temperatures in the CRTS III ballastless track slab due to daytime sunlight can cause warpage deformation, leading to periodic rail irregularities that increase the wheel-rail impact of high-speed vehicles and accelerate track structure damage. Therefore, it is necessary to study the dynamic contact relationship between the composite slab and the base plate during vehicle running. The results of the study show that: 1) Under the influence of temperature gradients, the composite slab tends to deform elliptically. With a positive temperature gradient, the middle part of the track slab bulges upward, causing the slab to be supported by its four corners. Conversely, with a negative temperature gradient, the four corners of the track slab bulge upward, resulting in the slab being supported by its center. 2) Temperature gradients can lead to separation between the composite slab and the base plate, reducing the contact area between layers. During vehicle running, the contact area between layers gradually increases, but the separation cannot be completely closed. 3) The temperature gradient significantly affects the vertical displacement of the track. The vertical displacement in the middle of the slab increases with a positive temperature gradient. In contrast, the vertical displacement at the ends of the slab increases with a negative temperature gradient. 4) The stress of self-compacting concrete at the side position significantly increases under a positive temperature gradient, with the vertical stress increasing by 2.7 times when the temperature gradient increases from 0 to 90 °C·m-1. [ABSTRACT FROM AUTHOR]

Abstract During the operation of load cell, heat is generated by the strain gauge and the electronics on the PCB board, which leads to temperature gradients within the sensor itself. These temperature gradients are unstable at different ambient temperatures. Compensation inaccuracies can also occur when compensating for sensor measurements at different temperatures This paper proposes a method to change the position of temperature compensation resistors to address errors caused by the temperature field effect of the strain gauge sensor itself. Without affecting the sensor’s strain measurement, the correctness of the proposed method is demonstrated through steady-state thermal simulation results in ANSYS and experimental results, effectively addressing errors caused by unstable temperature gradients during the operation of strain gauge sensors.

Solar energy is one of the most important and promising energy sectors in the world. Batteries that convert sunlight into electrical energy could become a replacement for traditional carbon-based energy sources. Vertical thin-film solar batteries are one of the new approaches to solar energy generation. The vertical configuration of solar panels provides maximum absorption of sunlight throughout the day. This orientation allows the batteries to capture solar energy even at low angles of incidence of the sun’s rays, which prolongs their operating time and improves the efficiency of electricity production. In this work, the authors proposed a three-dimensional model of a vertically oriented solar battery, as well as they calculated and evaluated the temperature characteristics and the efficiency obtained under conditions of changing ambient temperature. Herewith the power densities of concentrated solar radiation with maximum values from 1 to 10 kW/m2 were varied. The distribution of the maximum values of the surface temperature of the solar battery has been studied. Also, the dependences of the maximum values of the solar battery temperature and the temperature gradient inside it, as well as the dependences of the minimum and maximum values of the heat flux from the solar battery surface on the time of day in the middle of January and July have been studied and plotted. As the calculations have shown, the maximum values of the temperature gradient inside the solar battery in January are ~47–50 % higher than in July. The potential difference, generated by the battery, reaches its maximum values from 11 a.m. to 4 p.m. both in January and July. The use of vertical thin-film solar batteries will improve the power generation efficiency and lower operating costs by reducing the influence of dust, rain and snow.

Direct preparation of glass-ceramics from slag is an efficient way to use the “slag” and “heat” of the slag, making this preparation a sought-after research topic. To prepare glass-ceramics using the Petrurgic method, this paper used silico–manganese slag as the main raw material, along with chromite and serpentine as modifiers. The Petrurgic method is a heat treatment process involving controlled crystallization during slag cooling to form glass-ceramics. The prepared glass-ceramic samples had a diameter of 100 mm and a height of 20 mm. Various tests and analyses such as X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy with energy dispersive X-ray spectroscopy, flexural strength, compressive strength, water absorption, and bulk density were performed on the samples. The influence of different heat treatment regimens on the phase composition and properties of silico–manganese slag microcrystalline glass was discussed. Additionally, the study investigated the temperature variation inside the glass-ceramic samples, and the results indicated that by modifying the slag and annealing it at 700℃ after cooling to the crystallization temperature, microcrystalline glass meets the performance requirements of natural granite. The temperature range of 900–1050 ℃ was found to be associated with the crystallization of the augite phase, while the temperature range of 1000–1050 ℃ was related to the crystallization of the akermanite phase. With improvements in the heat treatment system, the amount of akermanite phase precipitation will increase, and the grain will become coarser than before. At 900 ℃, the grain growth of the microcrystalline glass was not as significant as that of the samples annealed at 1000 ℃ and 1050 ℃, and the lack of excessive crystallization led to fewer defects inside the glass-ceramics. After studying the temperature profile data, it was observed that during the heat treatment process at 1000–1050 ℃, inconsistent crystallization between the inner and outer parts of the sample resulted in a temperature gradient from the center to the edge. After studying the temperature profile data, it was observed that during the heat treatment process at 1000–1050 ℃, inconsistent crystallization between the inner and outer parts of the sample resulted in a temperature gradient from the center to the edge. However, at 900 ℃, the temperatures of the central and edge regions remained consistent during the crystallization stage. For the heat treatment at 800 ℃, the slag temperature quickly decreased below 900–1050 ℃, making crystallization difficult. The overall trend of the temperature difference between the central and side parts of the sample was similar for all four heat-treatment conditions. After casting the slag into the mold, temperature gradients were formed within the sample. These formations do not affect the types of crystalline phases that precipitate; however, they do affect the quantity of crystallization.

Purpose – Temperature is an important load for a ballastless track. However, little research has been conducted on the dynamic responses when a train travels on a ballastless track under the temperature gradient. The dynamic responses under different temperature gradients of the slab are theoretically investigated in this work. Design/methodology/approach – Considering the moving train, the temperature gradient of the slab, and the gravity of the slab track, a dynamic model for a high-speed train that runs along the CRTS III slab track on subgrade is developed by a nonlinear coupled way in Abaqus. Findings – The results are as follows: (1) The upward transmission of the periodic deformation of the slab causes periodic track irregularity. (2) Because of the geometric constraint of limiting structures, the maximum bending stresses of the slab occur near the end of the slab under positive temperature gradients, but in the middle of the slab under negative temperature gradients. (3) The periodic deformation of the slab can induce periodic changes in the interlayer stiffness and contact status, leading to a large vibration of the slab. Because of the vibration-reduction capacity of the fastener and the larger mass of the concrete base, the accelerations of both the slab and concrete base are far less than the acceleration of the rail. Originality/value – This study reveals the influence mechanism of temperature gradient-induced periodic deformation in the dynamic responses of the train-track system, and it also provides a guide for the safe service of CRTS III slab track.

In order to study the unstable vibration of generator unit in nuclear power plant, a rotor dynamics analysis model was established, in which the thermal effect induced by oil shear flow in bearing was considered. One-dimensional energy balance equation was used to solve the journal temperature difference caused by the flow of lubricating oil in the bearing small gap. The average journal temperature difference and its angle during a whirling cycle were obtained. The effect of cross-sectional temperature gradient on shaft bending deformation was calculated, and the equivalent bending moment was obtained. The equivalent bending moment was input to the shaft in finite element model, and the bending deformation of the generator shaft was calculated. The results show that the temperature difference of the journal is induced by the shear flow of lubricating oil in the bearing clearance. The temperature difference of the journal increases with the increase of journal eccentricity and bearing clearance. After the eccentricity of the journal increases to a certain extent and the bearing clearance decreases to a certain extent, the temperature difference of the journal section increases rapidly, exhibiting typical nonlinear characteristics. If the amplitude of synchronous whirling orbit increases, the dynamic eccentricity increases and the cross-sectional temperature difference increases. Journal temperature difference of a certain nuclear power generation unit was calculated using the model. Within a reasonable range of bearing parameters in nuclear power units, the temperature difference can reach 10 ℃. Its impact on vibration is equivalent to the impact of G2.5 level imbalance force on the generator. The periodic vibration fluctuation phenomenon that occurred on a certain type of nuclear power unit was introduced. Test shows that the fluctuation amplitude is related to the lubricating oil temperature. It is pointed that the journal temperature difference produces rotational unbalance, resulting in vibration fluctuation. Unstable vibration is related to lubricating oil viscosity, bearing clearance, eccentricity ratio and unbalanced force. The unstable vibration can be reduced by reducing the viscosity of lubricating oil, increasing the bearing clearance, reducing the eccentricity and unbalance. The engineering verification test of adjusting lubricating oil temperature was carried out. The test results show that increasing the temperature of lubricating oil to reduce the temperature viscosity of lubricating oil is helpful to reduce the unstable vibration. The analysis results by calculation are consistent with the engineering practice. The model established in this study can be used for the analysis of unstable vibration of nuclear power generator units.

Sn–Ag solders are widely used for advanced electronic packaging. The combined effect of Ag element and temperature gradient (TG) on the formation of Sn grains in Cu/Sn-xAg/Cu micro solder joints was elucidated systematically. Numerous small-sized β-Sn grains were formed in both Cu/Sn/Cu and Cu/Sn-0.5Ag/Cu micro solder joints after reflow with or without TG. The Cu/Sn-0.5Ag/Cu joint was found to have more twinning β-Sn structures. The formation of the multiple β-Sn grains in these two joints was attributed to the presence of multiple tetrahedral metastable short-range order (SRO) structures which acted as nuclei for the nucleation and growth of β-Sn. The existence of TG slightly enhanced the preferred orientation characteristics of Sn grains. For the joints with Ag content was or higher than 2 wt%, several Sn grains were formed without TG, while a single or highly oriented Sn grains were observed with TG. The number and orientation of Sn grains were affected by the combined effect of Ag element and TG significantly. The β-Sn grains formed without TG were based on the {101} type cyclic twinning configuration clusters that stabilized by Ag atoms and acted as nuclei. The formation of a single or highly preferred β-Sn grains was benefit from the combined effect of Ag element and TG. The results provide theoretical guidance for optimizing the composition of Sn–Ag solders and controlling the microstructure of the joints, thereby contributing to the advancement of electronic packaging technologies.

A two-step joining approach was proposed to minimize or eliminate decomposition bubbles in laser joining metal to polymer. Finite element simulation was utilized to analyze the temperature distribution and incorporated the bubble shrinkage mechanism and thermal capillary effect, providing the theoretical basis for explaining the reduction in bubbles and their movement. Two experimental setups were employed: with and without laser beam offset. In experiments without offset, the bubbles after the second joining process underwent significant shrinkage, resulting in a notable reduction in volume. In offset experiments, the bubbles not only reduced in size but also exhibited movement and elimination. This was induced by the laser beam offset, which created a temperature gradient perpendicular to the joining direction, triggering thermal capillary effects that caused the bubbles to migrate towards the hotter side and eventually escape from the joint edges. Consequently, the joints obtained through double welding exhibited higher fracture stress as compared to those obtained through single welding. The theoretical analysis of the bubble reduction mechanism aligned with experimental observations, further validated by camera images.

The paper is devoted to the study of temperature and stress distribution in the medium-pressure rotor of the K-200-130 turbine, which are of considerable interest when predicting the durability of this equipment and extending its operation beyond the service life. A geometric model of the most loaded part of the rotor – from the middle of the shaft neck in the thrust bearing area to the 5th stage disc – was developed. The study of the thermal and stress-strain state of the rotor during start-up from a cold state was performed in a two-dimensional formulation using the finite element method. The non-stationary problem of heat conduction during start-up was solved. The obtained results indicate a fairly uniform thermal state during variable operating conditions. The largest temperature gradient (1200–2200 K/m) is observed at the time points from the rotor push to the synchronization of the turbine generator with the power system. After the turbine generator is loaded with up to 30 MW of electric power, a decrease in the temperature field irregularity and its gradual stabilization are observed. It was found that when operating at the nominal steam parameters, the maximum metal temperature is 508 °C in the region of the control stage and decreases when the distance from it increases. The stress-strain state of the rotor was evaluated taking into account the unevenness of temperature fields during start-up, stresses from thermal expansion, and centrifugal forces. The highest stresses are characteristic of the moment when the turbine comes to idle in the area of thermal compensation grooves of the rotor and the control gate and amount to 440–472 MPa. It is noted that these areas are the most likely zones of ring crack nucleation during turbine start-up operations. Subsequently, the stress level gradually decreases as the turbine unit reaches its rated power. It has been established that the most stressed area of the rotor during stationary operation is the area of the axial bore under the control stage and its diaphragm seal (121–134 MPa)

This study aimed to elucidate the influence of various culture medium components, including carbon sources, nitrogen sources, inorganic salts, suspension agents, and temperature, on the mycelial growth characteristics of Phallus dongsun. Employing single-factor experiments and response surface methodology within glass Petri dishes, the research identified that carrot powder, soybean powder, and ZnSO4 notably enhanced the proliferation of aerial mycelium, significantly augmenting the growth rate of P. dongsun mycelium. The resultant mycelium was observed to be dense, robust, and fluffy in texture. In particular, ZnSO4 markedly accelerated the mycelium growth rate. Furthermore, xanthan gum was found to effectively modulate the medium’s viscosity, ensuring a stable suspension and facilitating nutrient equilibrium. The optimal cultivation temperature was determined to be 25°C, with mycelial growth ceasing below 5°C and mycelium perishing at temperatures exceeding 35°C. The optimal medium composition was established as follows: wheat starch 5 g/l, carrot powder 5 g/l, soybean powder 7.50 g/l, glucose 10 g/l, ZnSO4 0.71 g/l, NH4Cl 0.68 g/l, xanthan gum 0.5 g/l, and agar 20 g/l. Under these optimized conditions, the mycelium of P. dongsun exhibited a rapid growth rate (1.04 ± 0.14 mm/day), characterized by a thick, dense, and well-developed structure. This investigation provides a theoretical foundation for the conservation, strain selection, and breeding of P. dongsun.

The temperature dependences of the thermoelectromotive force of chromium mono and disilicides in the temperature range 200℃÷+600℃ have been studied. For chromium disilicide, the dependence of the thermopower coefficient (α) on temperature (T) has three sections. Chromium monosilicide is characterized by a smooth increase in thermopower with increasing temperatures up to 200℃, and then its constancy. It was revealed that silicides rich in chromium atoms have lower thermopower values than silicides rich in silicon. The maximum thermo-EMF values of 110 μV/K and 190 μV/K were observed for chromium mono- and disilicides, respectively. It was revealed that for chromium silicides the dependence of the dimensionless parameter Q = Z∙T on temperature is linear. The possibility of predicting the technology of synthesis of semiconductor material with optimal thermoelectric properties using the dependence of thermopower on conductivity and the parameter Q on temperature is shown.

The nonlinear free vibrations of elastically supported fiber-reinforced polymer cylindrical shells (FRPCSs) under temperature gradient conditions are investigated using both theoretical and tested techniques. A dynamic model of the FRPCSs with consideration of such complex thermal conditions is firstly established based on the first-order shear deformation theory in conjunction with Hamilton's principle, the Galerkin method, the artificial spring technique, etc. Numerical results at room temperature and in a uniform thermal environment with classical or arbitrary boundary conditions are utilized to give a rough validation of this model. Subsequently, a thermal-vibration system is set up to measure the nonlinear natural frequencies of two FRPCS specimens subjected to four different temperature gradient conditions in free-free boundary constraints, and iterative calculations are performed to identify the temperature-dependent material properties. Finally, the detailed comparisons of calculated and experimental results provide a solid validation of the proposed model. This study offers a practical model tool to forecast the nonlinear free vibrations of the FRPCSs in a complex thermal environment, which can be readily adjusted and extended to other forms of composite shells. Also, the predicted and measured results can help assess the structural thermal-vibration behaviors when the temperature gradient effect needs to be considered. Communicated by Makoto Ohsaki. [ABSTRACT FROM AUTHOR]

This study investigates the feasibility of utilizing the finite element method (FEM)-based conductive heat transfer (CHT) analysis simulation to determine temperature gradients and solidification rates at the solid–liquid interface during laser beam oscillation welding. By comparing experimental observations with FEM-based CHT analysis, the underlying microstructural evolution and grain formation during welding were examined. FEM-based CHT enables the calculation of temperature gradients (G) and solidification rates (R), offering insights into the formation of equiaxed structures, which are crucial for suppressing hot cracking. Columnar-to-equiaxed structure transition thresholds, such as G/R and G3/R, accurately predict the emergence of fully equiaxed grain structures, validated by electron backscatter diffraction. This research provides valuable insights into temperature gradients and solidification rates in oscillation welding, guiding process design for achieving refined equiaxed structures and minimizing hot cracks. [ABSTRACT FROM AUTHOR]

This research paper focused on investigating the influence of various factors on steady Couette flow beneath a permeable bed. Factors studied included aligned magnetic field, thermal radiation, temperature gradient heat source, viscous dissipation, and Joules dissipation. The momentum and energy equations governing flow and heat transmission were analytically solved to predict the generation of entropy. The findings were visually presented through graphical representations, which effectively demonstrated the effect of these factors on the fluid's velocity, temperature, entropy production, and Bejan number. In addition, the shear stress and rate of heat transfer coefficient at the channel walls were computed and their behavior was documented in tables to provide further insights. [ABSTRACT FROM AUTHOR]

In the process of preparing polycrystalline silicon using Al-Si alloy purification, the enrichment of primary silicon can effectively reduce the consumption of aluminum and acid in the subsequent pickling process, thereby lowering the separation cost of high-purity primary silicon. Electromagnetic directional solidification is one of the best methods for preparing polycrystalline silicon currently due to its advantages such as simple process and strong controllability. However, there is a lack of systematic research on how various process parameters affect the enrichment of primary silicon. Therefore, this study investigates the effects of initial solidification temperature, crucible initial position, and descent rate on the behavior of primary silicon enrichment during the solidification process of Al-50% Si (mass fraction) alloy, and characterizes the morphology of primary silicon grains within the enrichment zone. The results show that when the initial solidification temperature is 950 ℃, the initial crucible position is -5 mm, and the crucible descent rate is 2 mm/h, primary silicon is mainly concentrated in the lower part of the ingot with a maximum enrichment rate of 79. 1%, which is the optimal combination of processes. At the same time, as the degree of primary silicon enrichment increases, the primary silicon grains change from "disk-like" to coarse "spherical", which helps reduce the inclusion of primary silicon and improve its purity. [ABSTRACT FROM AUTHOR]

Copyright of Atomic Energy Science & Technology is the property of Editorial Board of Atomic Energy Science & Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work conducted an exploring study to minimize porosity cavities in a 300 mm × 2000 mm slab by mechanical heavy reduction when it has solidified. Real density measurements of slab samples indicated that, with a heavy reduction of 20 mm to slab after behind its solidification end, slab center was much denser and much more consistent. Porosity volumes at 1/4 and 1/2 width regions of slab were minimized from 5.19 × 10−4 cm3/g to 1.29 × 10−4 cm3/g and from 2.27 × 10−4 cm3/g to 1.05 × 10−4 cm3/g, respectively. Original Position Statistical-Distribution Analysis (OPA) of larger sampled slabs indicated that the heavy reduction was efficiently penetrated from slab surface into center to heal porosity cavities. Obtained results indicated positive influences of heavy reduction in healing porosity holes in slab even after solidification, when the temperature gradient of slab surface and center was about 280 °C. [ABSTRACT FROM AUTHOR]

Copyright of Micronanoelectronic Technology is the property of Micronanoelectronic Technology Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Aiming at the problem of moist and thermal coupling effect of winter aqueduct, the finite element model of temperature field, humidity field and humid heat coupling field of concrete box aqueduct with different environmental parameters was established by using Fluent finite element software. Taking an aqueduct in Northwest China as an example, the ambient temperature, ambient humidity and wind speed from January 5 to January 20, 2023 were measured, and the influence of different working conditions on the temperature effects of the aqueduct in the uncoupled and fully coupled state in winter was analyzed. The analysis results show that the most unfavorable temperature difference in winter when the aqueduct is open to water is - 14. 7 ℃ and - 6. 3 ℃ when it is not water. The most unfavorable transverse temperature difference in winter when the aqueduct is open to water is - 10. 2 ℃ and - 6. 2 ℃ when no water is not connected. In the process of humidity diffusion, the humidity in the direction of plate thickness gradually decreases from inside to outside, and the water absorption rate decreases with the increase of time. In the process of moist and thermal coupling, the temperature value of the fully coupled field is less than the temperature value of the non-coupling field, the deflection change value of the fully coupling action of humidity and heat is less than the deflection change value under the non-coupling of humidity and heat, and the tensile stress of the moist and thermal coupling action is less than the tensile stress value under the non-coupling of moist heat, therefore, the full coupling of humidity and heat is beneficial to the deformation of the aqueduct structure. [ABSTRACT FROM AUTHOR]

As the water pipe cooling system is widely applied to controlling temperature in mass concrete structures, the precise simulation of the temperature field in mass concrete with cooling pipes embedded is meaningful. This paper presents an isogeometric analysis (IGA) with NURBS for heat transfer in mass concrete with consideration of the cooling pipe. The proposed method not only achieves the same level of accuracy with fewer nodes but also eliminates the time-consuming process of mesh in the traditional FEM. The coarsest parameter space which depicts small pipe and large concrete precisely is constructed to create an efficient model for numerical computation. In addition, the unique k-refinement in IGA is supposed to be the most appropriate encryption mechanism, and the knot insertion vector for effective refinement is calculated by considering the characteristics of temperature gradient distribution around the cooling pipes. In addition, a different calculation parameter has been discussed to show the stability and flexibility of the IGA. The obtained numerical results demonstrate the accuracy and efficiency of the proposed scheme in the simulation of transient temperature fields in concrete structures with cooling systems. [ABSTRACT FROM AUTHOR]

Direct-current gas-insulated switchgear (DC GIS) is an important device for promoting the lightweight and compact design of offshore wind power platforms. Gas pressure and temperature gradients are crucial factors that must be considered during the design process of the DC GIS. In this study, the multi-physics coupling model of basin insulators considering surface charge accumulation was established, and the corresponding real-sized insulator surface charge measurement platform was constructed. The effects of gas pressure and temperature gradient on the surface charge accumulation characteristics were investigated, respectively. The results show that the effect of gas pressure on the surface charge distribution characteristics depends on the dominant mode of surface charge. When volume conduction is dominant, the effect of gas pressure on the surface charge is negligible. However, when gas conduction is dominant, the accumulation of a uniform charge pattern on the insulator surface increases with the rise in gas pressure. Furthermore, due to gas convection, the temperature of the upper part of the DC GIS is significantly higher than that of the lower part, which leads to a temperature difference between the upper and lower surfaces of the insulator. The charge density on the insulator upper surface near the central conductor rises with the increase in load current. [ABSTRACT FROM AUTHOR]

Bridge early warning based on structural health monitoring (SHM) system is of significant importance for ensuring bridge safe operation. The temperature-induced deflection (TID) is a sensitive indicator for performance degradation of continuous rigid frame bridges, but the time-lag effect makes it challenging to predict the TID accurately. A bridge early warning method based on nonlinear modeling for the TID is proposed in this article. Firstly, the SHM data of temperature and deflection of a continuous rigid frame bridge are analyzed to examine the temperature gradient variation patterns. Kernel principal component analysis (KPCA) is used to extract principal temperature components. Then, the TID is extracted through wavelet transform, and a nonlinear modeling method for the TID considering the temperature gradient is proposed using the support vector machine (SVM). Finally, the prediction errors of the KPCA-SVM algorithm are analyzed, and the early warning thresholds are determined based on the statistical patterns of the errors. The results show that the KPCA-SVM algorithm achieves high-precision nonlinear modeling for the TID while significantly reducing the computational load. The prediction results have coefficients of determination above 0.98 and fluctuate within a small range with clear statistical patterns. Setting the early warning thresholds based on the statistical patterns of errors enables dynamic and multi-level warnings for bridge structures. [ABSTRACT FROM AUTHOR]

Diurnal and seasonal temperature variations cause uniform temperature changes, vertical temperature gradients, and horizontal temperature gradients. Vertical temperature gradients occur when the bridge deck absorbs heat due to solar radiation more than the bottom parts of bridge girders. Consequently, the vertical temperature gradient causes redistribution of bearing reactions, and induces additional flexural stresses in continuous spans. Estimating the vertical temperature gradient effect on continuous concrete bridges requires knowledge of thermal analysis of statically indeterminate structures or advanced three-dimensional (3 D) finite element (FE) analysis. Therefore, this article focuses on developing a simplified analysis method for estimating vertical temperature variations effects on continuous prestressed concrete bridge girders, which is required for bridge design. Restraint moments induced by vertical temperature gradients are investigated using 3 D FE analysis. A total of 115 bridges with different configurations (number of spans, girder spacing, and girder type) were analyzed to estimate the positive thermal moments at support locations. Results from these analyses were then used to develop simplified equations for estimating the positive restraint moments due to vertical temperature gradients from AASHTO LRFD Bridge Design Specifications (BDS). The developed equations are validated using John James Audubon Bridge #2 field data, and for other AASHTO LRFD temperature zones. [ABSTRACT FROM AUTHOR]

Desiccation tolerance of pathogenic bacteria is one strategy for survival in harsh environments, which has been studied extensively. However, the subsequent survival behavior of desiccation-stressed bacterial pathogens has not been clarified in detail. Herein, we demonstrated that the effect of desiccation stress on the thermotolerance of Escherichia coli O157:H7 in ground beef was limited, and its thermotolerance did not increase. E. coli O157:H7 was inoculated into a ground beef hamburger after exposure to desiccation stress. We combined a bacterial inactivation model with a heat transfer model to predict the survival kinetics of desiccation-stressed E. coli O157:H7 in a hamburger. The survival models were developed using the Weibull model for twodimensional pouched thin beef patties (ca. 1 mm), ignoring the temperature gradient in the sample, and a three-dimensional thick beef patty (ca. 10 mm), considering the temperature gradient in the sample. The two-dimensional (2-D) and three-dimensional (3-D) models were subjected to stochastic variations of the estimated Weibull parameters obtained from 1,000 replicated bootstrapping based on isothermal experimental observations as uncertainties. Furthermore, the 3-D model incorporated temperature gradients in the sample calculated using the finite element method. The accuracies of both models were validated via experimental observations under non-isothermal conditions using 100 predictive simulations. The root mean squared errors in the log survival ratio of the 2-D and 3-D models for 100 simulations were 0.25-0.53 and 0.32-2.08, respectively, regardless of the desiccation stress duration (24 or 72 h). The developed approach will be useful for setting appropriate process control measures and quantitatively assessing food safety levels. [ABSTRACT FROM AUTHOR]

High-quality, large-size CaF2 crystals are urgently needed for advanced applications such as deep ultraviolet lithography and aerospace cameras. However, growing such crystals is a challenging task in the field of crystal growth. Heat transfer, flow, and phase change processes of 3, 7, and 20 inch (1 inch =2. 54 cm) CaF2 crystals at different growth stages on the vertical Bridgman growth were conducted by numerical simulation. The results show that as the crystal size increases, the melt flow strength and the area of heat dissipation on the crucible wall increase, resulting in problems such as local depression of the melt-crystal interface, increase in the radial temperature difference, reversal of the temperature difference between the crystal edge and center, and decrease in the axial temperature gradient near the melt-crystal interface. Furthermore, this article discusses optimization strategies for growth rate and power of heater in the growth of large-size CaF2 crystals. [ABSTRACT FROM AUTHOR]

The repair of magnesium alloy castings is of great importance in terms of engineering and economic benefits. This study employs the cold welding technique to repair the ZM5 alloy, and the effects of current and preheating treatment on the microstructure and mechanical properties were investigated. The increase in current exacerbates the cracks, while the preheating treatment can effectively control them. However, the liquefaction cracks occur near the heat-affected zone after preheating at 300 °C. The microstructure of the repaired zone shows finer dendritic structure consisting of α-Mg and β-Mg17Al12 phases. After preheating treatment, the repaired zone shows the microhardness of 72 HV0.1, higher than the non-preheating samples (65 HV0.1), and the substrate (63 HV0.1). The average tensile strength of the preheated samples is 110 MPa higher than the non-preheating samples, and reaching 88.7% of the substrate. The fracture mechanism for both the substrate and repaired samples was brittle failure. [ABSTRACT FROM AUTHOR]

New types of instabilities associated with crystal anisotropy during thermomigration of rectilinear and curvilinear (annular) zones under the action of a temperature gradient in the silicon-aluminium system are experimentally revealed. A force model of thermomigration is improved, which takes into account vectors of resistance forces to atomic-kinetic processes at the dissolution front. This model explains the observed features of the stable and unstable motion of the linear zones. Reasons and a mechanism of thickenings and kinks of the ends of rectilinear zones, their fragmentation and decay, as well as transformation of annular linear zones into triangular and square zones during thermomigration in the < 111 > and < 100 > directions, respectively, were also explained. [ABSTRACT FROM AUTHOR]

The priming effects (PEs) of soil organic carbon (SOC) decomposition is a crucial process affecting the C balance of terrestrial ecosystems. However, there is uncertainty about how PEs will respond to climate warming. In this study, we sampled soils along a subtropical elevation gradient in China and conducted a 126‐day lab‐incubation experiment with and without the addition of 13C‐labeled high‐bioavailability glucose or low‐bioavailability lignin. Based on the mean annual temperature (MAT) of each elevation (9.3–16.4°C), a temperature increase of 4°C was used to explore how PEs mediate the decomposition of SOC in response to warming. Our results showed that the magnitude of glucose‐induced PEs (PEglucose) was higher than lignin‐induced PEs (PElignin), with both PEs linearly increasing with MAT. Across the MAT (i.e., elevation) gradient, short‐term warming had a constant magnitude of negative effects on PEglucose, whereas rising MAT exacerbated the negative effects of short‐term warming on PElignin. Moreover, the temperature sensitivity of SOC decomposition decreased after adding glucose and lignin across the MAT gradient, suggesting that fresh C inputs may prime the microbial breakdown of labile SOC under warming. Taken together, warming alleviated SOC loss due to PEs through varying mechanisms depending on substrate bioavailability. Warming mediated the PEglucose by increasing available nitrogen and weakening microbial nitrogen‐mining but inhibited the PElignin by shifting from microbial nitrogen‐mining to microbial co‐metabolization. Our findings highlight the role of warming in regulating the PEs and suggest that incorporating the suppression effect of warming on PEs can contribute to the accurate prediction of soil C dynamics in a warming world. Plain Language Summary: Tropical and subtropical ecosystems have the highest vegetation productivity and diversity on earth and play a crucial role in regulating climate change. However, it is unclear how diverse plant‐derived components stimulate microbial decomposition of soil organic carbon (SOC) via a phenomenon called priming effects (PEs) under climate warming. Here, we added two 13C‐labeled substitutions of plant components (e.g., glucose and lignin) to soils collected from a subtropical elevation gradient and carried out a 126‐day lab‐incubation experiment. Warming consistently harmed glucose‐induced PEs (PEglucose), while amplified the negative effect on lignin‐induced PEs (PElignin) across the elevation gradient, suggesting that warming has stronger negative effects on PElignin at warmer sites. Warming mediates the PEglucose by weakening microbial N‐mining but strengthening microbial preferential substrate utilization. This is achieved by reducing substrate‐built microbial biomass and making more substrate for respiration compared to unwarmed soil. In contrast, warming inhibits lignin‐induced PEs by shifting from microbial N‐mining to microbial co‐metabolization. This shift is supported by the positive association between lignin‐induced PEs and lignin‐derived microbial biomass and available nitrogen. Our measurement suggests that warming decreased the intensity of SOC decomposition by downregulating the primed SOC loss with fresh substrate inputs through varying mechanisms depending on substrate bioavailability. Key Points: Soil C priming effect linearly decreases with elevation in subtropicsHigh‐ and low‐quality substrates play opposite but complementary roles in soil C feedback to climate warmingThe suppression effect of warming on priming can contribute to the accurate prediction of soil C dynamics in a warmer world [ABSTRACT FROM AUTHOR]

The initiation of the first crack mainly determines the criteria for glass failure. However, the extended consequences of cracking, with the formation of multiple cracks merging, result in fallout conditions under varying thermal loads that become more critical. Point-supported glass arrangements are globally used in high-rise and energy-efficient buildings for architectural ingenuity aimed at a low budget. However, the formation of cracks due to thermal load resulting in glass breakage could infuriate the overall fire dynamics of the enclosed area. Therefore, experimental study and prediction of glass failure become very crucial. The present experimental study focuses on finding the most critical parameter that may quantify the cause of glass failure and further breakage in fallout conditions under varying thermal loads. 45 experiments were carried out on float glass of 300 × 300 mm2 with 4 mm, 6 mm, 8 mm, 10 mm, and 12 mm with continuous fuel supply arrangements. Critical parameters analysed were the time of crack initiation, glass temperature at the time of cracking, maximum temperature difference at glass failure, and thermal strain caused by the temperature difference on the glass surface. The range of minimum and maximum temperature difference recorded on the glass surface for the present study was between 30–35°C and 55–60°C at the breakage time for all the experiments. The Maximum temperature difference measured was 56.99°C on the 12 mm glass surface, and the corresponding maximum thermal strain found was 482 × 10−6 mm/mm. The maximum heat release rate was found to be approximately 200 kW. Maximum heat flux was found in the range of 10.33 kW/m2 to 21.14 kW/m2. A correlation was also developed using the least square method for all the thicknesses, which is well correlated with the glass thickness per unit length.

A thorough understanding of the reactor core thermal hydraulic behavior is essential for the design and safety analysis of Sodium-cooled Fast Reactors (SFR). Due to the application of hexagonal subassembly, the core thermal hydraulic behavior is significantly affected by the flow field within the subassemblies, the inter-wrapper region and the hot pool. Analysis of the core thermal hydraulic behavior requires a model coupling the three regions mentioned above, which has been identified as one of the thermal hydraulic challenges in SFR. In the present study, a 3D model that covers the three regions was developed for the core of the China Experimental Fast Reactor (CEFR) with the Computational Fluid Dynamic (CFD) code, Fluent. The inter-wrapper region and the hot pool were modeled in detail, while the subassemblies were modeled with a special porous medium model. The core thermal hydraulics behavior under steady state was studied, more specifically, information for the flow field distribution at the core outlet, the inter-wrapper flow and the duct wall temperature distribution was obtained. Under steady state, liquid sodium in the inter-wrapper region is supplied by the inner region of the hot pool. And it enters the inter-wrapper region from the core outer region and returns back to the hot pool inner region from the core central region. The inter-wrapper flow is cooled by non-fuel subassemblies and heated up by fuel subassemblies. For non-fuel subassembly, the ratio of the total heat transfer rate between the inter-wrapper flow and the subassemblies to the heat generated within subassemblies could reaches 96%; for fuel subassemblies, the maximum ratio of the total heat transfer rate between the inter-wrapper flow and the subassemblies to the heat generated within subassemblies is 2.45%. Significant temperature gradients have been observed on the duct wall, with maximum values of 156.69 K/m in the vertical direction and 2,196.00 K/m in the circumferential direction. The largest temperature gradient appears on the duct of subassemblies adjacent to the transition region of fuel subassemblies and non-fuel subassemblies.

The use of polymers for water storage or distribution is closely monitored, especially with regard to the possible contamination with substances coming from the material's surfaces. Different standards are practiced across countries according to type of applied materials and such test methods are prevalently based on constant temperature conditions. However, these polymers systems could be located in diverse environment which does not necessarily provide constant conditions. Experimental findings show that exposure of liquid inside polymeric materials to specific temperature gradients, and consequently to emerging organized flows, can result in an accelerated leaching of undesirable substances from the solid surface. In presented work model steady-state and organized flow conditions are used to compare release of contaminates from polyethylene by measuring of surface tension, UV–Vis spectroscopy, FTIR, scanning electron microscopy and elemental analysis of polymer surfaces and water leachates. The pilot study shows that convective flow generated via temperature gradient significantly affects contaminant release in comparison to a steady state and mixing flow conditions.

To further study adiabatic parameters distortion, the adiabatic decomposition of 2,4-DNT, 20%DTBP, and 45%Glucose was systematically analyzed using thermal analysis calorimetry and numerical simulation methods. The study revealed the variation laws and influence mechanisms of the temperature gradient effects and thermal inertia in adiabatic systems. A numerical model for decomposition in a closed adiabatic system was developed by integrating the apparent kinetics into the CFD code. The results show that the temperature gradient effects during adiabatic decomposition initially increase and then decrease until reaching zero. The temperature gradient effects become more pronounced as the exothermic characteristics of substances increase. They are the most significant at the peak self-heating rate, with gradients of 182.4 °C·cm−1, 21.6 °C·cm−1, and 0.78 °C·cm−1, respectively. Specific data segments for adiabatic analysis should maintain α values below 0.138 for 2,4-DNT, 0.484 for 20%DTBP, and should utilize complete 100 % adiabatic data for 45%Glucose, aiming to mitigate potential distortion in adiabatic parameters. Furthermore, Фeff varies with the reaction, initially increasing and then decreasing in deviation from the theoretical value, with peak deviations of 60 %, 20 %, and 0.3 % for three substances, respectively. These findings lay the foundation for further optimizing the temperature gradient effects and establishing a dynamic Фeff correction model.