Effect Of Loading Research Articles

Destabilization of Cylindrical Shells Coupling Effect of Local Impact Load and Circumferential Pressure

Destabilization of Cylindrical Shells Coupling Effect of Local Impact Load and Circumferential Pressure

Biodiesel Production from Waste Cooking Oil Using Recombinant Escherichia coli Cells Immobilized into Fe3O4-Chitosan Magnetic Microspheres.

Developing reusable and easy-to-operate biocatalysts is of significant interest in biodiesel production. Here, magnetic whole-cell catalysts constructed through immobilizing recombinant Escherichia coli cells (containing MAS1 lipase) into Fe3O4-chitosan magnetic microspheres (termed MWCC@MAS1) were used for fatty acid methyl ester (FAME) production from waste cooking oil (WCO). During the preparation process of immobilized cells, the effects of chitosan concentration and cell concentration on their activity and activity recovery were investigated. Optimal immobilization was achieved with 3% (w/v) chitosan solution and 10 mg wet cell/mL cell suspension. Magnetic immobilization endowed the whole-cell catalysts with superparamagnetism and improved their methanol tolerance, enhancing the recyclability of the biocatalysts. Additionally, we studied the effects of catalyst loading, water content, methanol content, and reaction temperature on FAME yield, optimizing these parameters using response surface methodology and Box-Behnken design. An experimental FAME yield of 89.19% was gained under the optimized conditions (3.9 wt% catalyst loading, 22.3% (v/w) water content, 23.0% (v/w) methanol content, and 32 °C) for 48 h. MWCC@MAS1 demonstrated superior recyclability compared to its whole-cell form, maintaining about 86% of its initial productivity after 10 cycles, whereas the whole-cell form lost nearly half after just five cycles. These results suggest that MWCC@MAS1 has great potential for the industrial production of biodiesel.

Oxygen evolution reaction activity of carbon aerogel supported Pd–Ni–Al catalysts synthesized by microwave irradiation method

The oxygen evolution reaction (OER) is a critical step for oxygen production during the electrochemical splitting of water. Effective OER catalysts support the development of clean energy technologies by increasing the energy efficiency of these processes. In this study, carbon aerogel (CA) was first synthesized as a catalyst support material using sol-gel, supercritical drying, and pyrolysis process. Then, mono-metallic (Pd/CA, Al/CA), bi-metallic (Pd–Al/CA, Pd–Ni/CA), and tri-metallic (Pd–Ni–Al/CA) catalysts were synthesized by microwave irradiation method. Inductively coupled plasma-mass spectrometry (ICP-MS), X-ray diffraction (XRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy have been made to examine the structural properties of the synthesized catalysts. Electrochemical analysis was carried out through cyclic voltammetry (CV), chronoamperometry, and electrochemical impedance spectroscopy (EIS) in alkaline media (1 M KOH: Methanol) to examine the effect of metal loading of CA support material towards OER performance. All the compositions showed excellent activity toward OER, among all Pd–Ni/CA catalysts showed the highest activity. The OER peak current increased remarkably up to 48 mA cm−2 with methanol addition, which signifies the substantial application of carbon aerogel supported-Pd-Ni-Al catalysts in direct methanol fuel cells (DMFCs). Pd–Ni/CA display high OER performance with maximum diffusion coefficient, Do (6.6 × 10−8 cm2 s−1) and heterogeneous rate constant, ko (4.706 × 10−4 cm s−1), and smaller value of Tafel slope (128 mV dec−1). Electrochemical studies predicted that all the prepared carbon aerogel supported-Pd-Ni-Al catalysts can be used as efficient catalysts for OER and other related electrocatalysis applications.

H2O2-assisted photo-electrocatalytic and photocatalytic degradation of methyl violet by CuO-modified TiO2 nanotube arrays

Photoelectrocatalytic degradation is an environmental friendly and efficient technique providing solutions for the dire issue of water pollution. TiO2 nanotubes are widely used as the photocatalyst but its efficiency is restricted by the wide band gap. This study deals with the fabrication of CuO-modified TiO2 nanotubes by electrochemical anodization following the hydrothermal method to enhance the photocatalytic degradation. Optical studies revealed a reduction in the bandgap (2.12 eV) of CuO-modified TiO2 nanotubes, which plays an important role in increasing the photocatalytic activity. The effect of CuO loading on TiO2 nanotubes in photocatalytic degradation as well as the effect of bias and H2O2 on photo-electrocatalytic degradation were studied. In photocatalytic degradation, 0.05 M CuO–TiO2 photocatalyst produced a maximum degradation of 49.5 % in 8 h. Compared with the pristine TiO2 nanotubes, the photodegradation of CuO-loaded TiO2 nanotubes increased by 16 %. Furthermore, when an external bias was applied, the photodegradation efficiency increased by 36 %. In addition of H2O2 to the PEC system, 0.05 CuO–TiO2 photocatalyst produced 100 % degradation of methyl violet in 2.5 h. Reusability studies showed that the photocatalysts are stable and can therefore be used for practical applications such as photocatalytic degradation and photoelectrochemical degradation of methyl violet.

Shear response of 〈110〉 asymmetric tilt grain boundaries in BCC-Fe

The present study investigated the effect of shear load on the 110 asymmetric tilt grain boundaries of body-centered cubic iron with molecular dynamics simulations. Various mechanisms like grain boundary (GB) sliding, shear-coupled migration, GB migration with rotation, GB decomposition, and GB deformation with dislocations emission were observed. Low-angle tilt GBs migrated with the help of two dislocation mechanisms, gliding and climbing. Two types of twin nucleation mechanisms were noticed in high-angle tilt GBs with varying tilt angles (η). For 16° ≤ η ≤ 112° and η ≥ 130° cases, dynamic self-adjustment of the atoms at the GBs caused GBs decomposition with the formation of twin boundaries (TBs). Newly nucleated TBs migrated under further applied shear load. For 112° < η < 130° case, TBs nucleated from the GB on either side of the misfit dislocations due to their localized core structure on the GB plane.

An optimizated additional damping control for suppressing ultra‐low frequency oscillation suppression based on SVC

AbstractThe ultra‐low frequency oscillation (ULFO) imposes an emerging stability challenge to the high proportion of hydropower grids. To suppress ULFO without reducing the primary frequency regulation of the hydro governor, a novel idea to exploit the voltage regulation effect of load is implemented. First, the additional damping controller is designed and configured in static var compensator (SVC), and the frequency analysis model considering the configuration of SVC as well as damping controller is established. Based on the model, the specific influence of SVC and controller on ULFO is analysed through eigenvalue calculation. In addition, the influence of various load models and SVC location on the damping level are further studied. Consequently, a parameter optimization design method for SVC additional damping control is proposed, it is modelled as the optimization problem of damping ratio in ULFO mode under multi‐operation conditions, which is solved by a particle swarm optimization algorithm. Finally, the effectiveness of the designed SVC additional damping controller is verified in the improved four‐machine two‐area power system and the actual power grid in China.

Review of Lithium-Ion Battery Internal Changes Due to Mechanical Loading

The growth of electric vehicles (EVs) has prompted the need to enhance the technology of lithium-ion batteries (LIBs) in order to improve their response when subjected to external factors that can alter their performance, thereby affecting their safety and efficiency. Mechanical abuse has been considered one of the major sources of LIB failure due to the changes it provokes in the structural integrity of cells. Therefore, this article aims to review the main factors that aggravate the effects of mechanical loading based on the results of different laboratory tests that subjected LIBs to abusive testing. The results of different cell types tested under different mechanical loadings have been gathered in order to assess the changes in LIB properties and the main mechanisms responsible for their failure and permanent damage. The main consequences of mechanical abuse are the increase in LIB degradation and the formation of events such as internal short circuits (ISCs) and thermal runways (TRs). Then, a set of standards and regulations that evaluate the LIB under mechanical abuse conditions are also reviewed.

Quantitative estimation of the effective elastic thickness around the Burma Plate and correlation analysis of its influencing factors

The Burma Plate is a microplate that extends along the boundary between the Indian and Eurasian plates. It is characterized by an extraordinarily complex lithospheric tectonic setting, resulting from the continental collision in the north, the oceanic crustal subduction in the south, and the large amount of sediment from the Tibetan Plateau. The lithospheric strength is a key to understanding the tectonic evolution of the Burma Plate. In this study, we use topography and gravity disturbance data to estimate the spatial distribution of effective elastic thickness Te, which is a measure of lithospheric strength. The Tevalues range from ∼10 km to 80 km, with higher values in the Indian Plate than those in the other regions. The non-isostatic flexural effects of sediment loading and subducting slab pull can bias the Te estimation, with maximum reductions of ∼50 km and ∼10 km, respectively. The consistent distributions of the Te and the shear wave velocity anomaly ΔVsat 100 km depth suggest that the lithospheric strength is generally controlled by the thermal structure of the upper mantle. Meanwhile, the Te variations are highly related to the geometry of the subducting Indian Plate along the collision and subduction zones, indicating that the plate tectonics play a dominant role in determining the lithospheric strength of the Burma Plate.

The study of the blast resistance performance of underground cavern support structures under the effect of explosive ground loads

The use of support structures with good explosion resistance to support and reinforce underground projects has become a focus of concern for relevant units in order to ensure the safety of underground projects in explosive ground loads. The blast resistance of underground caverns and the influence of support parameters on blast resistance have been studied when lining and pre-stressing anchors are supported individually under dynamic and static coupling. Straight-walled arched caverns are chosen for this study because of their strong blast resistance. The influence of excavation unloading on the support structure was analyzed under the condition of a burial depth of 500 m. The study investigated the blast resistance of caves supported solely by singular concrete lining support and singular pre-stressed anchor bolt support. The research findings indicate that pre-stressed anchor bolts significantly limit the deformation capacity of surrounding rock while lining is more effective in restricting the vibration response of surrounding rock. The pre-stressed anchor bolts ensure operation within the strength range throughout the entire process with no alteration in load-bearing capacity. Increasing the thickness of the lining can reduce the vibration response of the cavern. Meanwhile, enhancing the pre-stressed anchor bolts within a certain range notably restricts the deformation response of the cavern. Therefore, the pre-stressed anchor bolts should be employed as the supporting structure to bear the excavation and unloading loads of the cavern.

Load effect of visual working memory on distractor interference: An investigation with two replication experiments.

Konstantinou et al. (Experiment 1B; Attention, Perception, & Psychophysics, 76, 1985-1997, 2014) reported that an increase in visual short-term memory (VSTM) load reduced distractor interference in the flanker task. Yao et al. (Experiment 3; Attention, Perception, & Psychophysics, 82, 3291-3313, 2020) replicated the design of Konstantinou et al.'s experiment and showed that the VSTM load did not modulate the distractor interference effect, contradicting the original findings. However, it is unknown whether differences in task-design between the two experiments contributed to the inconsistent results. Therefore, we first replicated the original two studies with Experiment 1 (N = 54) and Experiment 2 (N = 54) and performed a statistical comparison between the data from these two experiments. In a third experiment (N = 28), we incorporated articulatory suppression into the design to exclude possible effects of verbalization. According to the ANOVA analyses, the VSTM load did not change the level of distractor interference in all three experiments, indicating that differences in task design alone do not explain the inconsistency.

Reliability design for bearing capacity of steel plate strengthened RC beams based on the improved design value method

AbstractThe partial factor method is widely employed as a design approach for structural reliability and serves as a crucial foundation for structural design codes. However, in practical applications, this method has gradually revealed shortcomings, such as issues with generality and insufficient precision in reliability control. In this article, an improved design value method for the bearing capacity design of steel plate strengthened RC beams was established. Additionally, considering the impact of the live‐to‐dead load effect ratio on the partial safety factor of resistance, a simplified expression for the ultimate limit state design of bearing capacity was proposed. The results show that the reliability index calculated using the partial factor method for the bearing capacity of steel plate strengthened RC beams has a significantly larger relative error. In contrast, the reliability indexes calculated based on the improved design value method are all greater than the target reliability index, ensuring the requirements of reliability design and providing a higher degree of precision in reliability control.

A cylindrical shell model with distributed springs for a rotating tire

In a companion paper (Vol. 248, Article 108227), we demonstrated the dependence of tire parameters on the modal characteristics of a stationary tire. For a more realistic scenario, when tire rotation is considered, the modal characteristics are veered due to centrifugal, Coriolis, and gyroscopic effects. In this paper, we study the forced vibration response of a rotating tire and also consider the effect of static load on modal characteristics. The tire tread is modeled as a cylindrical shell and the sidewall is modeled using distributed springs in axial, circumferential, and radial directions. The tire inflation pressure is accounted for, which generates pre-stresses in the tire belt in circumferential and axial directions. The material model incorporates an orthotropic composite structure of the tire with multiple stacked layers of steel belt reinforcing. The governing equations of motion of the rotating shell are derived and further reduced to the corresponding eigenvalue problem. Galerkin’s projection with orthogonal basis functions is used to obtain the natural frequencies and associated mode shapes. For the forced vibration, the tire is excited by a harmonic point load at a fixed location, and the response is calculated by superimposing the basis functions of the free vibration problem. The analytical model predictions are compared against the computation finite element (FE) model developed in ABAQUS® and experimental modal testing results. To understand the effects of rotation on wave propagation, dispersion relations were obtained, and the wave number spectrum of the rotating tire was compared with that of the stationary one. Finally, to understand the dependence of natural frequencies on tire rotation and normal load, Campbell diagrams and frequency response functions (FRFs) were obtained from the proposed model. The model shows a fairly good agreement with experimental results and FE simulations.

Effect of biocatalysts β-galactosidase loading in their performance in the kinetically controlled synthesis of lactulose

β-galactosidase from Kluyveromyces lactis has been immobilized on chitosan-glutaraldehyde particles employing different enzyme loadings (in a range of 0.7–7 mg/g of support). The biocatalysts had been later utilized to produce lactulose by transglycosylation using milk whey supplemented with fructose. The amount of produced lactulose decreased when the enzyme loading increased, from around 18 mg/mL using the biocatalysts with only 0.7 mg/g to around 7 mg/mL using the biocatalyst with a loading of 7 mg/mL. The results showed in this paper shows the great effect of the substrates and product concentration gradients inside the biocatalyst particle, not only lactulose, but also glucose and galactose. That is, the use of a excessive enzyme loading can lead to a significant worsening of the β-galactosidase biocatalyst performance in kinetically controlled synthesis.

Effect of contact blast loading on the plastic deformation forming ability of large steel pipes

Plastic deformation forming with metal pipe blanks by contact blast loading inside pipes is an interesting moldless forming technique, also a complex and error-prone process. Some advantages are very characteristic of this forming technique such as no cost of mold, tooling and low energy consumption, no complicated control equipment compared to other forming techniques such as casting, rolling, tube hydrostatic forming, bending – welding. Up to now, the calculation and design of this forming technique mainly use some existing reference empirical formulas, so the experimental results are only suitable in the range of small pipe diameters, and still there are significant deviations for larger pipe diameters. In order to increase the predictability and accuracy of forming process by contact blast loading inside large pipes, this paper presents a study on the influence of the mass of highly explosive material – TNT to the forming ability of large steel pipes from API-5LX-42 mild steel materials by modern 3D numerical simulation – using Abaqus/Cae software. Four output criteria with maximum values are used to evaluate the efficiency of this forming process, including maximum diameter of the blast zone (Dmax£2D0), Von Mises stress (Smax£UTS), Hoop plastic strain component (PE22max£1), and Pipe wall thinning rate (eT-max£60 %). The results of this research on the plastic deformation forming process using numerical simulation can be used for the next experimental step to evaluate the difference between simulation and experiment, as well as use this data in the calculation and design of pipe products with circular or square cross-sections to save both time and money of trial and error before application in actual manufacturing

Compressive load analysis of mechanical setting process of test string Packer in Ultra-high-pressure Gas Wells

ABSTRACT To address the packer setting problems under complex operating conditions in ultra-high pressure gas wells, a mechanical analysis model for the mechanical setting process of packer in ultra-high pressure gas wells is established. The model takes into account factors such as wellbore trajectory, bending moment, internal and external fluid pressure, and the coupled effect of axial load, frictional resistance and buckling. The established model can be used to calculate the axial force of tubing string in ultra-high pressure gas wells, and analyze the effects of the tubing string length below packer, line weight combination, friction coefficient and the released wellhead suspended load on the packer setting force. The case calculation and parameter sensitivity analysis indicate that the original design of a high-pressure gas well cannot meet the requirements of packer setting. The setting performance of the packer can be effectively improved by adjusting the released wellhead suspended load, optimizing the tubing string length below the packer, reducing the friction coefficient and optimizing the length configuration of tubing string with small diameter. An increase in wellhead release weight by 60 kN was accompanied by a corresponding increase in packer pressure of 12.48 kN. When the lower string length was extended by 600 m, the packer weight without suspension was reduced by 65.34 kN, whereas the packer weight with release was diminished by 21.69 kN. Furthermore, an augmentation in the friction coefficient by 0.15 resulted in a decrease in the pressure weight of the packer under release suspension by 55.79 kN. Additionally, a reduction in the small pipe diameter length by 1000 m caused an increase in the packer weight with a release load of 17.98 kN. The research content not only provides theoretical guidance for the long-term safety of test string in high-pressure gas wells, but also offers practical insights for the design and operation of packers.

Scalar Inferencing, Polarity and Cognitive Load

According to the Polarity Hypothesis, the presence or absence of a processing cost for Scalar Inferences (SIs) depends on their polarity. This hypothesis predicts, among other things, that the processing of lower-bounding SIs should not be affected by cognitive load the same way upper-bounding SIs are. To date, evidence in support of this prediction comes from the comparison between upper-bounding and lower-bounding SIs elicited by disparate scalar words. In this paper, we report on two dual-task experiments testing this prediction in a more controlled way by comparing upper-bounding and lower-bounding SIs arising from the same scalar words or scale-mates operating over the same dimension. Results show that, for these more minimal comparisons, lower-bounding SIs involve comparable cognitive demands as their upper-bounding counterparts. These findings challenge the idea that load effects are consistently modulated by SI polarity and suggest instead that these effects are relatively consistent across different types of SIs.

The Effects of Vertical Load and Gaps on Lateral Resistance of Fork-Column Dougong in Traditional MultiStory Wooden Structures

ABSTRACT This article investigates the mechanical performances of the Fork-Column Dougong (FCDG), also named as Cha-Zhu-Zao Dougong, which is a common type of connection between the upper and lower columns in a traditional multistory Chinese wooden building. Numerical results of a typical FCDG under different vertical loads illustrate that the vertical load can strengthen the lateral stiffness of FCDG to some extent. Because existing FCDGs have different lengths of column limbs in their construction, the effect of this variation on the lateral behavior of the FCDG is also studied with reference to the different contact states between different components of the FCDG. The FCDG without gaps between its components gives generally better lateral behavior according to the lateral force-displacement curve. Because the column is the main member of the structure to carry the structural load transferred through by contact between the column limbs and the supporting Fangs. The length of column limbs would directly affect the effective contact area at the bottom and roots of column limbs, and the variation of the contact area would change the bearing capacity and load path of the FCDG. Results from this study may serve as reference to the restoration and protection of traditional Chinese wooden structures.

Direct reduction of calcium carbonate by coupling with methane dry reforming using NiO/S-1 as catalyst

Thermal decomposition of carbonate is an important process in the production of cement, refractory materials, and steel. Nevertheless, this process requires high temperature and is always accompanied with large amounts of CO2 emission. To reduce the decomposition temperature and simultaneously mitigate CO2 emissions, direct reduction of carbonate under a reducing atmosphere has been proposed as a novel strategy. This work mainly investigated the feasibility of direct reduction of CaCO3 by CH4 in the presence of a highly dispersed NiO/S-1 catalyst. It was found that the introduction of a CH4 atmosphere without a catalyst had little promotion effect on CaCO3 decomposition (as compared to air atmosphere), and no notable conversion of CO2 was observed. However, the presence of a highly dispersed NiO/S-1 catalyst significantly decreased the decomposition temperature of CaCO3 in a CH4 atmosphere, and most of the carbon species in CaCO3 can be converted to CO. To gain a comprehensive understanding of CaCO3 reduction in CH4, the effects of reaction temperature, CH4 concentration, and NiO loading in the NiO/S-1 catalyst were systematically explored. With the best-performing catalyst, i.e., 7NiO/S-1, complete CaCO3 decomposition and approximate 90 % CH4/CO2 conversion can be achieved under the condition of 750 °C and 25 vol% CH4. Characterization results indicated that the CaO particles obtained in the CH4 reducing atmosphere exhibited a more porous structure compared to that attained in air, due to the more intensive CaCO3 decomposition in CH4. Further data analysis revealed that reverse water-gas shift reaction also contributed to CO2 conversion during the reduction of CaCO3 in CH4. The findings obtained in this research can provide new perspectives for CO2 emission control and energy saving in traditional heavy-emission and high energy consumption industries.

Intermittent cyclic stretch of engineered ligaments drives hierarchical collagen fiber maturation in a dose- and organizational-dependent manner

Hierarchical collagen fibers are the primary source of strength in tendons and ligaments; however, these fibers largely do not regenerate after injury or with repair, resulting in limited treatment options. We previously developed a static culture system that guides ACL fibroblasts to produce native-sized fibers and early fascicles by 6 weeks. These constructs are promising ligament replacements, but further maturation is needed. Mechanical cues are critical for development in vivo and in engineered tissues; however, the effect on larger fiber and fascicle formation is largely unknown. Our objective was to investigate whether intermittent cyclic stretch, mimicking rapid muscle activity, drives further maturation in our system to create stronger engineered replacements and to explore whether cyclic loading has differential effects on cells at different degrees of collagen organization to better inform engineered tissue maturation protocols. Constructs were loaded with an established intermittent cyclic loading regime at 5 or 10 % strain for up to 6 weeks and compared to static controls. Cyclic loading drove cells to increase hierarchical collagen organization, collagen crimp, and tissue tensile properties, ultimately producing constructs that matched or exceeded immature ACL properties. Further, the effect of loading on cells varied depending on degree of organization. Specifically, 10 % load drove early improvements in tensile properties and composition, while 5 % load was more beneficial later in culture, suggesting a shift in mechanotransduction. This study provides new insight into how cyclic loading affects cell-driven hierarchical fiber formation and maturation, which will help to develop better rehabilitation protocols and engineer stronger replacements. Statement of significanceCollagen fibers are the primary source of strength and function in tendons and ligaments throughout the body. These fibers have limited regenerate after injury, with repair, and in engineered replacements, reducing treatment options. Cyclic load has been shown to improve fibril level alignment, but its effect at the larger fiber and fascicle length-scale is largely unknown. Here, we demonstrate intermittent cyclic loading increases cell-driven hierarchical fiber formation and tissue mechanics, producing engineered replacements with similar organization and mechanics as immature ACLs. This study provides new insight into how cyclic loading affects cell-driven fiber maturation. A better understanding of how mechanical cues regulate fiber formation will help to develop better engineered replacements and rehabilitation protocols to drive repair after injury.

Influence of Artificial Pit on Corrosion Fatigue Behavior of 316LN SS and Its Weldment

AbstractThe effect of cyclic loading on smooth and pre-pitted type 316LN stainless steel and its weldment in acidified chloride environment is investigated in this study. The onset of fatigue cracks at the bottom of the pit is brought on by the maximum stress concentration effect in acidified chloride environment. Pre-pitted specimens exhibit a more pronounced fatigue life reduction compared to smooth specimens at lower stress amplitudes. The growth of a microscopic crack from an artificial pit, which is influenced by the combined effects of the pit electrolyte and stress concentration factor, is vital for maintaining structural integrity.