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Based on the enzymatic saccharification of the various pulps in the previous 0.8 l ultrasonic stirred tank reactor, the ultrasound-enhanced saccharification of waste papers such as newspaper, carton paper, office paper etc. was carried out in the same reactor as well as larger scale stirred tank reactors of size 3.2 and 6.4 l. The saccharification of each waste paper was less enhanced in the larger reactor at a given ultrasonic intensity. This could be attributed to the decrease in the ultrasonic intensity per reaction volume, i.e., the specific ultrasonic intensity. Most waste papers were more efficiently hydrolyzed with increasing specific ultrasonic intensities, although newspaper was less efficiently done for a too high specific intensity. Such an adverse effect might be due to the fact that some impurities in the newspaper such as lignin were activated by an intensive ultrasonic irradiation to form a rigid and closed network, which inhibited the access and adsorption of cellulase on to the substrate surface. The previous kinetic model was found to be applicable to analyze and simulate the saccharification of each waste paper in the different ultrasonic reactors. The ultimate conversion of a substrate based on the total sugar concentration estimated for an infinite reaction time could be correlated as a function of the ratio of initial substrate to enzyme concentrations at a fixed specific ultrasonic intensity. Either the apparent rate constant or the ultimate conversion increased and tended to approach a constant with an increase in the specific ultrasonic intensity except for the case of newspaper, while neither the apparent Michaelis constant, product inhibition constant nor glucose formation equilibrium constant was influenced by the specific ultrasonic intensity. [Copyright &y& Elsevier]

The article offers information on the American Society of Mechanical Engineers (ASME) Pressure Vessel and Piping Conference that was held in Vancouver, Canada in July 23-27, 2006. The papers presented in sessions about the transportation, storage and disposal of radioactive materials focused on issues such as global safety standards, packaging radioactive materials, and the safe transport of these materials.

The choice of material, manufacturing process, and molding tool significantly affects the quality, environmental impact, and cost efficiency of composite components. Producing one-piece hollow profiles with smooth inner surfaces and undercuts presents major challenges for conventional mold concepts. There is yet no thorough review of shape-variable mandrels in composite manufacturing to be found in the literature. This paper provides an overview of research on shape memory polymers and other shape-variable materials used in tooling applications for composite manufacturing. This work covers shape memory, heat shrink, and other deformable tooling concepts that enable the production of one-piece Type V pressure vessels, air intake ducts, or curved struts and tubes. A systematic literature review in combination with a state-of-the-art open-source active learning tool ASReview is conducted. Fifteen relevant studies were identified. Research on shape-variable tooling is mainly conducted by three research groups in the USA and the PRC. The tooling is mostly made of unreinforced thermosets, especially styrene-based ones. Thermoplastic resins are less common, and reinforcements limit the usable elongation in the temporary shape. The shape variability is either a shape memory and/or a softening process, which, in all studies, is activated by heating. Release agents are widely used to ease demolding. No ecological or economical assessment of the manufacturing methods was conducted in the reviewed studies. Three fields for further research that could be identified are as follows: (1) thorough ecological end economical assessment of shape-variable mandrels in comparison with conventional tooling; (2) thermoplastic shape memory polymer mandrels; and (3) further investigation of simulation capabilities for shape memory mandrels. [ABSTRACT FROM AUTHOR]

Hydro-pneumatic energy storage is a form of compressed-air energy storage that can provide the long-duration storage required for integrating intermittent renewable energies into electrical power grids. This paper presents results based on numerical modelling and laboratory tests for a kilowatt-scale HPES system tested at the University of Malta. This paper presents measurements of the discharge cycle, in which energy stored in compressed air within a pressure vessel is hydro-pneumatically converted back into electricity via a Pelton turbine and fed into the national electricity grid. The tests were conducted using a hydraulic turbine operated under different fixed-turbine rotational speed settings, with the pressure being allowed to decrease gradually during the HPES system's discharge cycle. The system's overall efficiency accounted for flow losses, turbine inefficiencies, and electrical losses. The tests showed that this efficiency was practically independent of the compressed-air pressure of specific water turbine runner speeds, despite the water turbine operating at fixed speeds. A numerical model developed in MATLAB Simulink (R2022a) was also presented for use simulating the hydraulic performance of the system during the discharge cycle. The model used secondary loss coefficients for the hydraulic circuit and derived velocity coefficients from computational fluid dynamics (CFD) for the Pelton turbine nozzle. We achieved very good agreement between the predictions based on numerical modelling and the measurements taken during laboratory testing. [ABSTRACT FROM AUTHOR]

The need for integrity evaluations and remaining life assessments of boilers arises from technical, economic, and legal reasons. The pulp and paper industry has less experience and tradition in using this engineering discipline when compared to other industries such as oil, petrochemical, and power generation. The pertinent Brazilian legal standard (NR-13) is concise in establishing this requirement, without providing details of applicable technical procedures. Furthermore, recovery boilers are a special type of steam generator, being very specific as to their inherent in-service degradation mechanisms and inspection needs. In view of the above scenario, pulp and paper mill engineers often have doubts and encounter diverse interpretations of the official regulations when they need to carry out integrity evaluations of quarter-century old recovery boilers. This paper relates CENIBRA's recent experience in evaluating its recovery boiler No. 1. [ABSTRACT FROM AUTHOR]

Fiber-reinforced polymer matrix composites are increasingly considered for lightweight cryogenic pressure vessels due to their excellent combination of tailorability, specific mechanical properties, and relatively low coefficients of thermal expansion. However, significant challenges must be overcome to fully utilize PMCs for cryogenic fuel tanks in terms of transverse microcracking and subsequent permeation of cryogenic fuel. Gas permeation and microcrack densities of cryogenically cycled composites are highly influenced by their layup, ply thickness, load case, and manufacturing defects like voids and resin rich zones. There has been a significant amount of research on measuring gas permeation of composites fatigued under pure thermal or uniaxial thermo-mechanical stresses. However, results demonstrate that the gas permeability should be measured under biaxial thermo-mechanical stresses to properly gauge the leakage characteristics of damaged composites. This paper summarizes the results from over a hundred papers on the key parameters that influence the gas permeability of composites, appropriate testing methods to cycle composites for permeability measurement, methods to limit the evolution of transverse microcracks, and materials traditionally used for the fabrication of all-composite cryogenic fuel tanks. Thin plies and nanofiller-toughening of the matrix have been shown to provide significant improvements in transverse microcrack suppression within cryogenically cycled composites. [ABSTRACT FROM AUTHOR]

Given that defect detection in weld X-ray images is a critical aspect of pressure vessel manufacturing and inspection, accurate differentiation of the type, distribution, number, and area of defects in the images serves as the foundation for judging weld quality, and the segmentation method of defects in digital X-ray images is the core technology for differentiating defects. Based on the publicly available weld seam dataset GDX-ray, this paper proposes a complete technique for fault segmentation in X-ray pictures of pressure vessel welds. The key works are as follows: (1) To address the problem of a lack of defect samples and imbalanced distribution inside GDX-ray, a DA-DCGAN based on a two-channel attention mechanism is devised to increase sample data. (2) A convolutional block attention mechanism is incorporated into the coding layer to boost the accuracy of small-scale defect identification. The proposed MAU-Net defect semantic segmentation network uses multi-scale even convolution to enhance large-scale features. The proposed method can mask electrostatic interference and non-defect-class parts in the actual weld X-ray images, achieve an average segmentation accuracy of 84.75% for the GDX-ray dataset, segment and accurately rate the valid defects with a correct rating rate of 95%, and thus realize practical value in engineering. [ABSTRACT FROM AUTHOR]

This paper presents a new hybrid genetic-particle swarm optimization (GPSO) algorithm for solving multi-constrained optimization problems. This algorithm is different from the traditional GPSO algorithm, which adopts genetic algorithm (GA) and particle swarm optimization (PSO) in series, and it combines PSO and GA through parallel architecture, so as to make full use of the high efficiency of PSO and the global optimization ability of GA. The algorithm takes PSO as the main body and runs PSO at the initial stage of optimization, while GA does not participate in operation. When the global best value (gbest) does not change for successive generations, it is assumed that it falls into local optimum. At this time, GA is used to replace PSO for particle selection, crossover and mutation operations to update particles and help particles jump out of local optimum. In addition, the GPSO adopts adaptive inertia weight, adaptive mutation parameters and multi-point crossover operation between particles and personal best value (pbest) to improve the optimization ability of the algorithm. Finally, this paper uses a nonlinear constraint problem (Himmelblau's nonlinear optimization problem) and three structural optimization problems (pressure vessel design problem, the welded beam design problem and the gear train design problem) as test functions and compares the proposed GPSO with the traditional GPSO, dingo optimization algorithm, whale optimization algorithm and grey wolf optimizer. The performance evaluation of the proposed algorithm is carried out by using the evaluation indexes such as best value, mean value, median value, worst value, standard deviation, operation time and convergence speed. The comparison results show that the proposed GPSO has obvious advantages in finding the optimal value, convergence speed and time overhead. [ABSTRACT FROM AUTHOR]

The large thickness COPV is designed by netting theory and the finite element simulation method, but the actual performance is low and the cylinder performance still cannot be improved after increasing the thickness of the composite winding layer. This paper analyzes the reasons for this and puts forward a feasible solution: without changing the thickness of the winding layer, the performance of COPV can be effectively increased by increasing the proportion of annular winding fiber. This method has been verified by tests and is supported by theory. [ABSTRACT FROM AUTHOR]

Paper quality depends on fiber diameter and wall thickness, and their derivatives. Fiber deformation occurs due to pressure from the vessel during development. The diameter and wall thickness of the fibers were measured following the direction of pressure exerted by the vessel on the face of the fiber cells. Fiber cell diameter measured perpendicular to and parallel with vessel enlargement was referred to as radial and tangential diameter, respectively, and likewise for fiber wall thickness. Differences in radial and tangential diameter and wall thickness of fiber cells in relation to their distance from vessels were analyzed. The radial diameter of fibers adjacent to large vessels decreased from the first to the fifth fiber, and from the first to the second fiber adjacent to small vessels. Conversely, tangential fiber diameter increased from the first to the fifth fiber for fibers adjacent to large vessels, and from the first to the second fiber adjacent to small vessels. The fibers adjacent to the vessel seem to have thicker walls in both the tangential than radial directions up to 2 and 5 fibers for small and large vessels, respectively. The first two fibers adjacent to small diameter vessels may produce higher strength paper than those up to five fibers from large diameter vessels, because the Runkel ratio, Coefficient of rigidity and Muhlsteph ratio values of fibers adjacent to small vessels are lower than fibers adjacent to large vessels. The opposite occurs for flexibility coefficient values. [ABSTRACT FROM AUTHOR]

Supercritical water oxidation is a promising technology for decomposition of industrial wastewater and sludge. However, the system is operated under high temperature and pressure (usually higher than 500 °C and 25 MPa). Corrosion of component materials and salt deposition may lead to leakage or even the burst of the pressure vessel in the SCWO system, resulting in a high level of worry about the safe operation of the system. In this paper, the safety management and accident- control strategies are introduced according to a commercial-scale SCWO plant in China. The safety management strategy refers to the special design and operation strategies of some facilities. Different types of potential accidents are analyzed and the coping strategies for accidents of different levels of severity are described in detail. The strategies are valuable for the safe operation of commercial SCWO plants and other plants operated in high temperature and high pressure. [ABSTRACT FROM AUTHOR]

In this paper, the effects of different designs of pressure vessels on hydrodynamic parameters and the performance of seawater RO systems are investigated using computer simulations. Simulation results showed that designs using pressure vessels with four membranes in two-pass RO systems have a lower energy consumption, 5.29 and 0.33 kWh/m3 for the first and second passes, respectively, than those with two or three membranes. Also, designs No. 4 and No. 10 were the most efficient, 41 and 56% for the first and second passes, respectively, compared to other ones. The first and second passes required a lower permeate and feed pressure when using designs No. 3, No. 6, No. 9, and No. 12 where pressure vessels with two membranes were used. In addition, hybrid designs of two-pass RO systems were found to have the best efficiency and the lowest energy consumption among various other designs. Findings showed that in two-pass RO systems, the first pass consumes more energy than the second pass. Thus, the efficiency of the second pass in all designs of two-pass RO systems is more than the first pass. The results presented in this paper can be used to optimize the design of two-pass RO systems to ensure the optimum operation of such systems. [ABSTRACT FROM AUTHOR]

2,6-Di-tert-butyl-4-methylphenol (BHT) is an excellent antioxidant that is easily oxidized to 2,6-di-tert-butyl-4-hydroperoxyl-4-methyl-2,5-cyclohexadienone (BHTOOH). For the safety of BHT production and usage, it is meaningful to study the thermal stability and decomposition properties of BHT and BHTOOH. In this paper, the thermal decomposition properties of BHT and BHTOOH were compared by the mini closed pressure vessel test (MCPVT) and differential scanning calorimetry (DSC). Their kinetics of thermal decomposition were studied using thermogravimetric analysis (TGA). The thermal decomposition products of BHT and BHTOOH were analyzed by gas chromatography-mass spectrometry (GC–MS). The results show that there was no significant change in temperature pressure when BHT was warmed up under a nitrogen atmosphere, indicating that BHT was stable within 400 K. The thermal decomposition reaction of BHTOOH was rapid with an initial reaction temperature of 375.2 K. The initial exothermic temperature (Ti) and heat release (QDSC) of DSC were 384.9 K and 865.0 J g−1, respectively. The apparent activation energies (Ea) for the thermal decomposition reactions of BHT and BHTOOH calculated by the Kissinger method were 151.8 kJ mol−1 and 66.07 kJ mol−1, respectively. The main decomposition products of BHT were isobutene and 2-tert-butyl-4-methylphenol. The thermal decomposition products of BHTOOH included BHT, 2,6-di-tert-butyl-4-ethylphenol, 3,5-di-tert-butyl-4-hydroxybenzaldehyde, 4,4′-(1,2-ethanediyl) bis [2,6-bis (1,1-dimethylethyl) phenol, etc. Based on the thermal decomposition behavior and products, the reaction pathway has been described. These results indicate that BHT is a potential thermal hazard during production, storage and application. For the safety of the chemical industry, the oxidation of BHT should be avoided. [ABSTRACT FROM AUTHOR]

Composite pressure vessels can be exposed to extreme loadings, for instance, impact loading, during manufacturing, maintenance, or their service lifetime. These kinds of loadings may provoke both visible and invisible levels of damage, e.g., fiber breakage matrix cracks and delamination and eventually may lead to catastrophic failures. Thus, the quantification and evaluation of such damages are of great importance. Considering the cost of relevant full-scale experiments, a numerical model can be a powerful tool for such a kind of study. This paper aims to provide a numerical study to investigate the capability of different modeling methods to predict delamination in composite vessels. In this study, various numerical modeling aspects, such as element types (solid and shell elements) and material parameters (such as interface properties), were considered to investigate delamination in a composite pressure vessel under low-velocity impact loading. Specifically, solid elements were used to model each layer of the composite pressure vessel, while, in another model, shell elements with composite layup were considered. Compared with the available experimental data from low-velocity impact tests described in the literature, the capability of these two models to predict both mechanical responses and failure phenomena is shown. [ABSTRACT FROM AUTHOR]

In pulse wave analysis, the changing curve of pulse wave strength with continuous increasing pressure, that is, the P-S (pressure-strength) curve, contains abundant human physiological information, but there is no accurate model to describe the formation mechanism of the curve. Therefore, this paper proposes a modeling method of the radial artery P-S curve based on the radial vibration of the vascular wall. The modeling method includes three parts. Firstly, based on hemodynamics, we proposed the blood motion equation in the pulsation process of healthy people. Secondly, the motion equation of the vascular wall based on the fluid–structure interaction between blood motion and vascular wall was established. Finally, according to the elastic theory of the vascular wall, the relationship between pulse strength and extravascular pressure of blood vessels was found. To verify the accuracy and applicability of the model, this paper simulated the changes in the vascular wall stress and the intravascular pressure with the extravascular pressure during the process of vascular deformation. In addition, 69 healthy volunteers were selected to participate in this study. Based on the gradient compression, the pulse strength envelope under the continuous pressure sequence of the radial artery, namely the pulse P-S curve, was extracted. We also analyzed the relationship between the individual P-S curve difference and BMI. The results show that the actual human body data collection and analysis results are consistent with the theoretical model established in this paper, which indicates that the model can provide a novel idea for the evaluation of the state of the human body. [ABSTRACT FROM AUTHOR]

Traditional welding quality inspection methods for pipelines and pressure vessels are time-consuming, labor-intensive, and suffer from false and missed inspection problems. With the development of smart manufacturing, there is a need for fast and accurate in-situ inspection of welding quality. Therefore, detection models with higher accuracy and lower computational complexity are required for technical support. Based on that, an in-situ weld surface defect recognition method is proposed in this paper based on an improved lightweight MobileNetV2 algorithm. It builds a defect classification model with MobileNetV2 as the backbone of the network, embeds a Convolutional Block Attention Module (CBAM) to refine the image feature information, and reduces the network width factor to cut down the number of model parameters and computational complexity. The experimental results show that the proposed weld surface defect recognition method has advantages in both recognition accuracy and computational efficiency. In summary, the method in this paper overcomes the limitations of traditional methods and achieves the goal of reducing labor intensity, saving time, and improving accuracy. It meets the actual needs of in-situ weld surface defect recognition for pipelines, pressure vessels, and other industrial complex products. [ABSTRACT FROM AUTHOR]

To study the form function and combustion characteristics of partially‐cut stick propellants, this paper derived and established the form function of this complex geometry propellant and analyzed the influence of cutting parameters on the form function. The analysis showed that partially‐cut stick propellants retain the high progressive combustion of multi‐aperture granular propellant, which is proportional to the distance between the notch and inversely proportional to the width of the notch. Based on this, partially‐cut stick propellants with different notches were prepared, and closed vessel tests were conducted. The experimental results showed that the notch had a significant effect on the combustion characteristics of the propellant. When there were notches, the wider the notch, the faster the pressure rise. The pressure in the closed vessel for stick propellants without notches rose the fastest. The burning rate of non‐notched or narrow‐notched fluctuated, while the burning rate of wide‐notched was stable. The dynamic vivacity data showed that the wider the notch, the more stable the change of the burning surface, and the combustion characteristic was closer to the granular propellant. Based on the analysis of form function and combustion characteristics, it is recommended that the notch width be 1 mm and the distance between notches on the same side should be the length of a granular propellant for the double‐base homogeneous 19‐perforated propellant studied in this paper. [ABSTRACT FROM AUTHOR]

Particle swarm optimization (PSO) is a population-based swarm intelligence algorithm that falls under the category of nature-inspired algorithms and is similar to evolutionary computing in various ways. Rather than the survival of the fittest, the PSO is driven by a representation of a social psychological model inspired by the group behaviors of birds and other social species. The particle's position is modified in PSO based on its position as well as velocity, while in quantum mechanics, the trajectory idea is absurd; however, the uncertainty principle suggests that a particle's position, as well as velocity, cannot be determined simultaneously. As a result, an advanced version of the quantum mechanics-based PSO method is proposed. The study in this paper is focused on an investigation of a new quantum-behaved PSO (QPSO) method called Gaussian quantum-behaved particle swarm optimization (GQPSO), which uses a mutation operator with a Gaussian distribution and is inspired by classical PSO methods and quantum mechanics concepts. In GQPSO, inadequate control parameter tuning results in poor solutions. To better understand the effect of different control parameters and their implications on GQPSO results, this paper used a full parametric sensitivity analysis on five different problems (the Design of a pressure vessel, Tension/Spring Compression, Rastrigin function, Ackley function, and Constrained Box Volume Problem). By adjusting each parameter one at a time, different optimization problems were used to investigate GQPSO. As a result, to allow particles to change their earliest best solution based on viability, a constraint-handling mechanism was developed. The optimal parameter set for GQPSO is provided based on the analysis of the results. With the help of the proposed optimal parameter set (contraction–expansion coefficient values as (1 = 1.6,2 = 1.3), swarm size as '350', and number of Iterations as '500'), GQPSO returned an optimized solution for Rastrigin and Ackley functions. It also performed better in the case of the design of a pressure vessel and tension/spring compression problems in comparison to the existing solution available in related literature. As per the findings of the sensitivity analysis, GQPSO is the most sensitive to the contraction-expansion coefficient in comparison to the maximum number of iterations (itermax) and swarm size ('n'). [ABSTRACT FROM AUTHOR]

For the exact solution of the stress in the functionally graded (FG) cylindrical/spherical pressure vessel, this paper presents a unified form of the basic equations of the FG hollow cylinder/spherical shell by introducing parameter, and then, the axial/spherical symmetry mechanical problems of FG hollow shells are studied under three different boundary conditions, respectively. Assume that the Young's modulus of the material changes with thickness distribution of cylinder/shell in the form of power functions and the value of Poisson's ratio is constant, the analytical solutions of the displacement and stress of the FG hollow cylindrical/spherical pressure vessel are derived under different boundary conditions. By comparing the analytical solutions of the FG hollow cylinder/spherical shell obtained in this paper with the existing classical theoretical solutions and numerical solutions, the correctness of the analytical solution given in this paper is verified. In the numerical discussion, the distributions of displacement, radial stress and circumferential stress of the FG hollow cylinder/spherical shell under different gradient parameters and different size conditions are given, respectively. Finally, based on the difference numerical method, the stress distribution of FG hollow cylinder/spherical shell with the Young's modulus and Poisson's ratio along thickness distribution in the form of power functions is analyzed numerically. The results show that gradient parameter and geometric size have a great influence on the mechanical response of FG structure under different boundary conditions. [ABSTRACT FROM AUTHOR]

This paper deals with guided wave-based structural health monitoring of composite overwrapped pressure vessels adopted for space application. Indeed, they are well suited for this scope thanks to their improved performance compared with metallic tanks. However, they are characterized by a complex damage mechanics and suffer from impact induced damage, e.g., due to space debris. After reviewing the limited progress in this specific application, the paper thoroughly covers all the steps needed to design and verify guided wave structural health monitoring system, including methodology, digital modelling, reliability, and noise estimation for a correct decision-making process in a virtual environment. In particular, propagation characteristics of the fundamental anti-symmetric mode are derived experimentally on a real specimen to validate a variety of finite element models useful to investigate wave interaction with damage. Different signal processing techniques are demonstrated sensitive to defect and linearly dependent upon damage severity, showing promising reliability. Those features can be implemented in a probability-based diagnostic imaging in order to detect and localized impact induce damage. A multi-parameter approach is achieved by metrics fusion demonstrating increased capability in damage detection with promising implication in enhancing probability of detection. [ABSTRACT FROM AUTHOR]

Pressure vessels having the structure of a cylindrical shell with a tangential nozzle are often used in engineering for some process requirements. But there are no accurate methods in engineering codes for the strength design of this special structure. In this paper, the limit–load analysis was performed to evaluate the weakening effects of the tangential nozzles on the strength of the cylindrical shells under internal pressure. A so-called strength–weakening coefficient was defined to reflect the weakening degree of the load-bearing capacity of the cylindrical shells by the tangential nozzles or specifically by the three dimensionless structural parameters, namely diameter ratio (do/Di), diameter-thickness ratio (Di/T) and thickness ratio (t/T). Results show that when increasing do/Di and Di/T or decreasing t/T, the strength–weakening coefficient increases, which means that the strength–weakening effect of the tangential nozzle on the cylindrical shell increases. With sufficient simulation results, regression equations for the strength–weakening coefficient were obtained which provides a reference for the strength design of cylindrical shells with tangential nozzles under internal pressure. [ABSTRACT FROM AUTHOR]

The nanoscale Cu-rich precipitates (CRPs) are one of the most critical microstructural features responsible for degrading the mechanical properties of reactor pressure vessel (RPV) steels. The prospect of the rapid regeneration of the service performance of degraded materials through electropulsing is attractive, and electropulsing has been proven to have the application potential to eliminate the CRPs and recover the mechanical properties of RPV materials. However, few studies have investigated the secondary service issue of electropulsing. This paper provides experimental findings from microstructural investigations and property evaluations of a FeCu RPV model alloy subjected to re-aging following recovery electropulsing and annealing treatments. The evolution behavior of CRPs and the changes in the hardness of the alloy during the re-aging process after electropulsing treatment were consistent with the initial aging process, while the re-aging process of the annealing treatment group was quite different from the initial aging. The difference between the electropulsing and annealing treatment groups was that the annealing treatment failed to eliminate the precipitates completely, leaving behind some large precipitates. This work demonstrates the potential application of EPT in this field. [ABSTRACT FROM AUTHOR]

Dissimilar metal welds (DMWs), widely used in many components of nuclear power plants, may cause catastrophic failures because of damages (such as corrosion). Pulsed eddy current testing (PECT) could be used for DMW detection for its advantages of broadband property and high lift-off immunity. However, the research on PECT for DMW detection has seldom been studied because its structure and material are complicated. In this paper, the detection and evaluation of flaws in DMWs are studied based on the transmitter-receiver (Tx-Rx) PECT probe. Simulation and experiment studies show that, for better detection accuracy, the Tx coil of the probe should be located above the pressure vessel, the Rx coil should be located above the weld, and the minimum distance between the Tx and Rx coils is suggested. Moreover, the peak value of the differential signal and the coefficient a1 of the fitted differential signals with a second-order Gaussian function can be used for defect evaluation. The research in this paper is beneficial for DMW detection by using PECT Tx-Rx probes. [ABSTRACT FROM AUTHOR]

Ion irradiation combined with nanoindentation is a promising tool for studying irradiation-induced hardening of nuclear materials, including reactor pressure vessel (RPV) steels. For RPV steels, the major sources of hardening are nm-sized irradiation-induced dislocation loops and solute atom clusters, both representing barriers for dislocation glide. The dispersed barrier hardening (DBH) model provides a link between the irradiation-induced nanofeatures and hardening. However, a number of details of the DBH model still require consideration. These include the role of the unirradiated microstructure, the proper treatment of the indentation size effect (ISE), and the appropriate superposition rule of individual hardening contributions. In the present study, two well-characterized RPV steels, each ion-irradiated up to two different levels of displacement damage, were investigated. Dislocation loops and solute atom clusters were characterized by transmission electron microscopy and atom probe tomography, respectively. Nanoindentation with a Berkovich indenter was used to measure indentation hardness as a function of the contact depth. In the present paper, the measured hardening profiles are compared with predictions based on different DBH models. Conclusions about the appropriate superposition rule and the consideration of the ISE (in terms of geometrically necessary dislocations) are drawn. [ABSTRACT FROM AUTHOR]

It is necessary to quantify the effects of flux on reactor pressure vessel steel embrittlement under neutron irradiation, if surveillance or high-flux test reactor data is used to predict vessel embrittlement occurring at lower fluxes. This is particularly important when considering embrittlement occurring during extended (60-80 years) operation for which there is no direct experience. Dedicated investigations are time-consuming and expensive even when only small flux-fluence ranges are investigated, so collating data from multiple campaigns is necessary to provide sufficient information to cover the wide range of fluxes required for vessel assessment in the long term. This paper collates and reviews such data. The review finds that flux dependences probably differ in sign and strength in different regimes (low flux and fluence, intermediate flux at low and high fluence, high flux at low and high fluence) with the regime limits affected by composition and temperature. The current understanding of diffusion processes and microstructural development are invaluable in interpreting the trends and limits. Many contradictory data sets were found, however, and not all contradictions could be dismissed as resulting from poor quality data. Suggestions are made for investigations to clarify the uncertainties. One wide-ranging model of flux effects, based on an extensive data set, is used to compare high-fluence data from different sources, to assess whether embrittlement rates accelerate after a high, threshold fluence. The model helps to identify experiments which investigated comparable fluxfluence-temperature regimes. The comparable data are split evenly between data sets supporting acceleration after a particular fluence and data sets contradicting it. The model identifies regimes in which further campaigns would clarify the causes of these contrasting observations. [ABSTRACT FROM AUTHOR]

The flow distribution characteristics at core inlet directly determines the thermal and hydraulic characteristics in the core, and it is closely related to the safety of nuclear reactor. The primary coolant is subjected to additional inertial force in ocean motion, which influence the flow distribution characteristics at core inlet. In the present paper, numerical simulation method is adopted to analyze the coolant flow distribution characteristics at core inlet of the Reactor Pressure Vessel (RPV) of a Small Reactor under rolling condition. Then the results of the flow distribution characteristics were compared with those under steady state. The results show the variation range of flow distribution factors in each channel under rolling condition is within 5%. And the uneven distribution of coolant at the core inlet increases with the increase of rolling amplitude, and decrease with the rolling period in short period. Standard deviation of flow distribution factor at the core inlet changes little under rolling condition, which indicates the flow distribution at the core inlet keeps good uniformity. [ABSTRACT FROM AUTHOR]

A recent development in Fault Tree Analysis (FTA), known as Dynamic and Dependent Tree Theory (D2T2), accounts for dependencies between the basic events, making FTA more powerful. The method uses an integrated combination of Binary Decision Diagrams (BDDs), Stochastic Petri Nets (SPN) and Markov models. Current algorithms enable the prediction of the system failure probability and failure frequency. This paper proposes methods which extend the current capability of the D2T2 framework to calculate component importance measures. Birnbaum's measure of importance, the Criticality measure of importance, the Risk Achievement Worth (RAW) measure of importance and the Risk Reduction Worth (RRW) measure of importance are considered. This adds a vital ability to the framework, enabling the influence that components have on system failure to be determined and the most effective means of improving system performance to be identified. The algorithms for calculating each measure of importance are described and demonstrated using a pressure vessel cooling system. [ABSTRACT FROM AUTHOR]

The development of cuffless blood pressure monitoring devices is attracting attention. The method of measuring vessel diameter from ultrasound A-mode waveforms is expected to be applied to daily blood pressure measurement due to the simplicity of the device. On the other hand, there is a problem in that the received intensity of the reflected wave from the blood vessel wall decreases due to displacement caused by body movement, resulting in incorrect measurement of the vessel diameter. In this paper, we examine how displacement of the positional relationship between the sensor and the blood vessel affects the measurement of blood vessel diameter and present a solution to the sensitivity reduction caused by angular displacement in the direction of the vessel axis by sending ultrasonic waves radially in the direction of the vessel axis. As a verification, a prototype sensor with an acoustic lens was fabricated. Evaluation of the sensor using a silicone resin tube model of a blood vessel showed that it maintained received intensity of about 50%of the strongest received intensity over a range of ±10°and the calculated blood vessel diameter was accurate to±0.05mm over a range of ±10°. Since this technology does not require a complex system, it is expected to be applied to devices that daily blood pressure measurement without the patient’s consciousness. [ABSTRACT FROM AUTHOR]

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Copyright of FME Transactions is the property of University of Belgrade, Faculty of Mechanical Engineering 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.)

Most WWER-440 reactors are operated over the planned operational lifetime of 30 years. Now, the owners/operators are preparing for the second phase of extending the operation. The paper presents an overview of the most important aspects of ageing of the main components of the WWER-440-type reactors based on the operational and ageing management experiences and primary research efforts supporting the operation. The paper aims to demonstrate that the expectations for the operability of these reactors for up to 60–70 years are realistic. The scope of the review is limited to the ageing of the reactor pressure vessel, vessel internals, and steam generator, which are the lifetime-limiting components besides the containment structure. Some of the corrective actions, improvements of in-service inspections, maintenance, and ageing management are also considered in the paper. It is shown that the selection of materials and unavoidable material degradation processes do not limit the operation of the WWER-440 reactors for up to 60–70 years under the established operational environment and ageing management practice. [ABSTRACT FROM AUTHOR]

Composite pressure vessels have the characteristics of light weight, corrosion resistance, good sealing, and high reliability, and have been widely used in military and civilian applications. With the widespread use of composite pressure vessels today, determining how to conduct scientific research and correct analysis becomes very important. With the continuous development of computer technology and the continuous improvement of finite element algorithms, the numerical calculation method has become an important method for studying composite pressure vessels. In this paper, the finite element analysis of filament wound composite pressure vessels is carried out by means of ANSYS and OpenSees. The semi-analytical method is used to optimize the design with the help of the Python tool. The parametric language is used to design different fiber layer schemes. The optimal fiber layer scheme is obtained by Nelder-Mead optimization function optimization. The optimal angle and thickness obtained after multiple iterations are 9.96875° and 0.03325 m, respectively. [ABSTRACT FROM AUTHOR]

States that the National Board of Boiler and Pressure Vessel Inspectors (NBBI), is searching for technical papers to present at their 66th General Meeting. Dates of meeting; Where meeting is to be held; Topics that papers should cover; Requirements of the paper; Deadline date for papers.

Research to better understand the phenomena influencing materials and components' performance is important for increasing the safety of Generation II and III nuclear plants. A crucial step for improving nuclear safety is the development of new experimental techniques that can provide the necessary data. The three H2020 projects presented in this paper, MEACTOS (2017–2022), INCEFA-SCALE (2020–2025), and FRACTESUS (2020–2024), cover the steps needed to realize those safety improvements. The goal of the MEACTOS project is to improve the resistance of critical locations, including welds, to environmentally-assisted cracking through optimizing surface machining and treatments. The project is currently in its final stage, and the complete analysis of the data is finished. The objective of INCEFA-SCALE is to improve predictions of component fatigue lifetime when subjected to Environmentally-Assisted Fatigue (EAF). The strategy consists of producing guidance on how to appropriately accommodate variable amplitude and plant-relevant loading in EAF assessments. Increasing the understanding of the EAF mechanism based on substantial testing, characterization, and analysis program will support the INCEFA-SCALE strategy. The FRACTESUS project will validate the use of miniaturized compact tension specimens by comparing the results of master curve-oriented fracture toughness tests performed with small and large specimens. The round-robin exercises will use irradiated and non-irradiated Reactor Pressure Vessel (RPV) materials. The material selection process is complete in time for the project to enter the testing phase. The output of the project will be beneficial from a long-term operation perspective and a saving in the material amount needed for RPV surveillance programs. Even though each project is devoted to different research areas, common aspects are clearly visible. All three projects investigate phenomena that are relevant to the performance and safe operation of the nuclear plant. Moreover, each project will provide valuable databases and analyses of test results for materials relevant to components in the nuclear plant. The output of these projects will be of great value to the nuclear industry. This paper presents the current progress for each project, emphasizing the common research domains between the projects. [ABSTRACT FROM AUTHOR]

Tourist submersibles are a new class of underwater vehicles where new materials and innovative structural concepts are used. Because of the lack of experience with these innovative vessels, prescribed rules of classification societies are not directly applicable in their structural design. Thus, a novel design-by-analysis approach, as given in the Boiler and Pressure Vessel Code of ASME, is employed for dimensioning structural components. Design-by-analysis stands for a consistent set of loads, boundary conditions, modelling principles, failure modes, and safety factors if the finite element analysis is performed instead of using rule formulas. The approach has been used until now in the structural design and optimization of unconventional pressure vessels, while in this paper it is for the first time employed in structural design of the underwater vehicle. This study can serve as guidance for future applications of design-by-analysis in the development of the innovative structures exposed predominantly to the pressure loading. [ABSTRACT FROM AUTHOR]

This paper proposes a novel nature-inspired optimization algorithm called the Fox optimizer (FOX) which mimics the foraging behavior of foxes in nature when hunting preys. The algorithm is based on techniques for measuring the distance between the fox and its prey to execute an efficient jump. After presenting the mathematical models and the algorithm of FOX, five classical benchmark functions and CEC2019 benchmark test functions are used to evaluate it's performance. The FOX algorithm is also compared against the Dragonfly optimization Algorithm (DA), Particle Swarm Optimization (PSO), Fitness Dependent Optimizer (FDO), Grey Wolf Optimization (GWO), Whale Optimization Algorithm (WOA), Chimp Optimization Algorithm (ChOA), Butterfly Optimization Algorithm (BOA) and Genetic Algorithm (GA). The results indicate that FOX outperforms the above-mentioned algorithms. Subsequently, the Wilcoxon rank-sum test is used to ensure that FOX is better than the comparative algorithms in statistically significant manner. Additionally, parameter sensitivity analysis is conducted to show different exploratory and exploitative behaviors in FOX. The paper also employs FOX to solve engineering problems, such as pressure vessel design, and it is also used to solve electrical power generation: economic load dispatch problems. The FOX has achieved better results in terms of optimizing the problems against GWO, PSO, WOA, and FDO. [ABSTRACT FROM AUTHOR]

We present a cross-cutting review of three on-going Horizon 2020 projects (ADVISE, NOMAD, TEAM CABLES) and one already finished FP7 project (HARMONICS), which address the reliability of safety-relevant components and systems in nuclear power plants, with a scope ranging from the pressure vessel and primary loop to safety-critical software systems and electrical cables. The paper discusses scientific challenges faced in the beginning and achievements made throughout the projects, including the industrial impact and lessons learned. Two particular aspects highlighted concern the way the projects sought contact with end users, and the balance between industrial and academic partners. The paper concludes with an outlook on follow-up issues related to the long term operation of nuclear power plants. [ABSTRACT FROM AUTHOR]

In this paper, we present an overview of all analytical engineering solutions delivered over the past 60 years for corrosion problems in pressure vessels. We briefly detail the strengths and weaknesses of existing approaches, thus demonstrating the need for novel uniform corrosion analysis methods for both current and new applications. To complement the review, we also present a new analytical model allowing the estimation of the lifetime of pressured elastic vessels with mechanically assisted corrosion. Both internal/external pressure and internal/external corrosion are captured, and dissolution-driven corrosion is also considered. The readily implemented method improves existing analytical approaches and is shown to be effective for thin and thick shells, as well as various loading and corrosion intensity and geometrical conditions. [ABSTRACT FROM AUTHOR]

With the development of the pressure vessel industry, high-energy wire welding has a great future. However, this means higher demands on the weldability of pressure vessel steels. Controlling inclusions via oxidative metallurgy is a reliable method of improving the weldability of pressure vessel steels. Hence, in this paper, experimental steels with different Mg element mass fractions were prepared using vacuum metallurgy. Simulated welding for high-heat input welding was carried out using the Gleeble-2000 welding thermal simulation test machine. The inclusions in the welding heat-affected zone (HAZ) in the experimental steels were observed using an optical microscope (OM) and scanning electron microscope (SEM). The compositions of the inclusions were analyzed using an energy-dispersive spectrometer (EDS). The research results indicated that the addition of Mg could increase the number density of the inclusions in the welding HAZ. With the addition of Mg from 0 to 5 wt.%, the total number density of the inclusions increased from 133 to 687 pieces/mm2, and the number density of the inclusions with a size of 0–5 μm2 increased from 122 to 579 pieces/mm2. The inclusions in the experimental steel welding HAZ with Mg elements were mainly elliptical composite inclusions composed of (Mg-Zr-O) + MnS. Moreover, MnS precipitated on the surface of the Mg-containing inclusions in the welding HAZ. Intragranular acicular ferrite (IAF) nucleation was primarily induced via the minimum lattice mismatch mechanism, supplemented with stress-strain energy and inert interface energy mechanisms. [ABSTRACT FROM AUTHOR]

Different applications or industries use different systems for linear actuation, such as hydraulic, pneumatic or electric. Electric systems are becoming increasingly popular and are already replacing hydraulic systems in various applications. These are known to be potentially harmful to the environment, as large amounts of fluid can be released into the environment in the event of a pipe burst or other accident. This paper presents the results of a comparison between hydraulic, pneumatic and electric systems under variable conditions but with similar loads in all three systems. The common feature of all three systems is the input power, which was limited to 1.1 kW. There was no hydraulic accumulator in the hydraulic system and no pressure vessel in the pneumatic system, so no stored energy could influence the system behaviour or results. The main difference between the systems studied was the profile of displacement and power consumption. The most consistent response and lowest power consumption were obtained with the electric system, although both hydraulic and pneumatic systems can achieve consistent response with some modifications. [ABSTRACT FROM AUTHOR]

Seawater reverse osmosis (SWRO) desalination has been in wide use for over 25 y. This paper examines limitations of the prevalent membrane configuration, based on a single stage consisting of one or more membrane housings operating in parallel with 6-7 elements per membrane housing. A brinestage configuration using interstage pressure boosting is proposed to address limitations in single stage systems including high biofouling potential, excessive permeate salinity and high energy consumption. Membrane array optimization requires careful review of concentration polarization (Beta or CP) and the feed flow rate through each membrane element (Qele), (a proxy for cross-flow velocity). CP is the formation of a salinity gradient normal to the membrane surface generated by a combination of boundary layer formation and permeation. CP is often characterized by the term Beta, which is defined as the ratio of salinity at the membrane surface divided by the bulk feed salinity. A high Beta means that the membrane surface is exposed to elevated salinity (hence higher osmotic pressure and increased salt passage) and a greater concentration of foulants. These conditions increase the required pressure, increases permeate total dissolved solids (TDS) and promotes fouling of membrane spacers and surfaces. A high Qele is preferred to minimize boundary layer thickness and to better scour feed channel spacers and the membrane surface. This paper explores a brine staged SWRO membrane array that achieves preferred levels of Beta and Qele to achieve improved biofouling resistance and lower permeate TDS while providing a recovery of 60% in typical SWRO applications using standard membranes, pressure vessels and energy recovery devices (ERDs). Major membrane suppliers have endorsed high recovery SWRO using brine staging as described in this paper. The focus also includes optimal ways to implement brine staging over very large SWRO systems using turbochargers in a unique configuration that maximizes brine stage performance as well as energy recovery efficiency. The paper also addresses related ERD technologies and variable frequency devices that together can reduce energy consumption as well as provide a substantial reduction in capital costs (CAPEX) and operating costs (OPEX) with realistic reductions of 16% in mega-scale SWRO facilities. [ABSTRACT FROM AUTHOR]

Crystal Structure Algorithm (CryStAl) is a new meta-heuristic algorithm, and it has been studied by many scholars because of its wide adaptability and the fact that there is no need to set parameters in advance. An improved crystal structure algorithm (GLCryStAl) based on golden sine operator and Levy flight is designed in this paper. The algorithm makes good use of the relationship between the golden sine operator and the unit circle to make the algorithm exploration space more comprehensive, and then gradually narrows the search space in the iterative process, which can effectively speed up the convergence rate of the algorithm. At the same time, a Levy operator is introduced to help the algorithm effectively get rid of the attraction of local optimal value. To evaluate the performance of GLCryStAl, 12 classic benchmark functions and eight CEC2017 test functions were selected to design a series of comparative experiments. In addition, the experimental data of these algorithms are analyzed using the Wilcoxon and Friedman tests. Through these two tests, it can be found that GLCryStAl has significant advantages over other algorithms. Finally, this paper further tests the optimization performance of GLCryStAl in engineering design. GLCryStAl was applied to optimize pressure vessel design problems and tension/compression spring design problems. The optimization results show that GLCryStAl is feasible and effective in optimizing engineering design. [ABSTRACT FROM AUTHOR]

In this paper, free vibration analysis of truncated conical shells reinforced with graphene nanoplatelets (GNPs) is studied. The composite shell is considered to be composed of epoxy reinforced with GNPs distributed along the thickness direction based on the various patterns. The shell is modelled based on the first-order shear deformation theory and effective material properties are calculated based on the Halpin-Tsai model along with the rule of mixture. The set of governing equations and boundary conditions are derived using Hamilton's principle and are solved numerically using generalised differential quadrature method for all possible combinations of clamped, simple and free conditions. Convergence and accuracy of the presented solution are confirmed and influences of various parameters on natural frequencies of the shell are investigated including boundary conditions, semi-vertex angle, circumferential mode number and also total mass fraction, width, thickness and distribution pattern of GNPs. Due to excellent mechanical and thermal properties of GNPs and wide application of conical shells in modern industries such as pressure vessels, aerospace structures and piping, results of this paper can be valuable and useful. [ABSTRACT FROM AUTHOR]

The paper presents the issues related to the design and assessment of the technical condition as well as determination of the residual durability of pressure equipment. Based on a real a example, a liquid nitrogen spherical tank, we present the development and applicability of the method for assessment of the durability of the structure. In terms of the material itself, the authors analyze macroscale (structural) factors of the geometry of the real structure (by 3D scanning: material wear detection, deflections and deformations, etc.) and measured real operational loads to develop an integrated method, including material model and behavior in its operational condition, delivering a useful tool for macroscale structural analyses of the materials under complex load (mechanical, thermal, chemical, etc.). As a result, a detailed analysis of the tank is presented. The paper gives an idea of the method, its development, usefulness, and applicability of the presented approach by indication of the mutual influence of pressure vessel components (e.g., stubs, manholes) and operational loads, which may result in underestimating the strength and durability of the pressure vessels in the design process and during operation. [ABSTRACT FROM AUTHOR]

Hydrogen has become a popular alternative energy to traditional fossil fuels due to its potential to contribute to a more sustainable future. It is recognized that the safety, efficiency, and economic aspects of hydrogen storage and transportation play an important role in the hydrogen energy industry. The development and commercialization of hydrogen energy are currently hindered by the structural integrity issue associated with hydrogen storage tanks. To tackle this structural integrity issue, a tangible structural health monitoring (SHM) technology is entailed for the health management of hydrogen storage tanks. Currently, flexible transducers are increasingly used to construct sensing systems and facilitate the deployment of SHM methods due to their superior properties such as conformality, low profile, and lightweight. This paper provides an overview of the SHM methods based on flexible sensing technology for hydrogen storage tanks. The most common damage modes caused by diverse factors during the service life for four types of hydrogen storage tanks are first summarized. The burgeoning flexible sensing technologies with corresponding damage characterization methods (including strain-based and elastic wave-based methods) are reviewed, and their applications in storage tanks are also discussed. On this basis, potential advancements and research topics regarding SHM systems based on flexible sensing technology for hydrogen storage tanks are discussed, and it is expected that flexible sensing technology will play a game-changing role in the future construction of SHM systems for hydrogen storage tanks. [Display omitted] • Flexible sensors are suitable for the SHM application of hydrogen storage tanks. • The sensor array and composite sensor-structure approaches are introduced. • Flexible piezoelectric transducers can provide guided waves with mode tuning. • Applying ultrasonic guided wave method to composite pressure vessels is limited. [ABSTRACT FROM AUTHOR]

The radial displacement of hydrogen storage composite overwrapped pressure vessel (COPV) is a key factor related to the collapse failure and burst pressure. However, there is still lack of effective method to monitor the radial displacement during the hydrostatic test and service process of the vessels. This paper proposed a method to measure the radial displacement based on fringe projection profilometry (FPP). Hydrostatic test with a composite overwrapped pressure vessel verifies the proposed method. The variation of displacement changing with inner pressures observed in the experiments is in agreement with that obtained from finite element analysis. Also Computed Tomography (CT) scanning is conducted and a widely spread micro defects is found in the composite layer of the cylinder. 78.9% of the total observed defects are small (<1000 mm2). In regions where large-sized defects (>1000 mm2) are concentrated, the total area of defects reaches 16,200 mm2. According to the statistical analysis, the strong correlation is found between the defects area and radial displacement. • Presented a novel method based on fringe projection profilometry (FPP) for monitoring the deformation of composite overwrapped pressure vessels (COPVs) during hydrostatic testing. • Employing 3D point clouds from FPP to reconstruct the cylinder and measure radial displacement. • The variation trend of radial displacement with pressure obtained by experiments is consistent with the finite element results. • Utilized Computed Tomography (CT) to detect and quantify micro delamination defects in the cylinders. • A significant correlation was found between the area of defects and radial displacement, while the relationship between the number of defects and radial displacement was less pronounced. [ABSTRACT FROM AUTHOR]