Contribution Ratio Research Articles

The Nature of Molecular Hybridizations in Nanodiamonds for Boosted Fe(III)/Fe(II) Circulation.

Reducing agents have been frequently utilized as electron donors for Fe(II) generation to resolve the sluggish Fe(III) reduction in Fenton-like reactions, while their irreversible consumption necessitates a robust catalytic system that utilizes green electron donors such as H2O2. In this study, we used annealed nanodiamonds (NDs) as a collection of model catalysts with different sp2/sp3 ratios to investigate the roles of the molecular structure in boosting the Fenton-like reactions. The annealed NDs acted as an electron mediator to transfer electrons from H2O2 to surface-adsorbed Fe(III) for Fe(II) generation as well as an electron donor for direct Fe(III) reduction, driving Fe(II)-catalyzed H2O2 decomposition to produce massive hydroxyl radicals, demonstrating potential in the real-water matrixes. Galvanic cell experiments show that the contribution ratio of mediation and electron donation is 2.75:1, indicating that the majority of Fe(II) was generated through electron transfer from H2O2. Additionally, different carbon configurations (sp-sp2-sp3 hybridizations) were compared to assess the molecular structure-performance relationships in Fe(III) reduction. This study unveils the distinct functions of carbon molecular structures in driving Fe(III)/Fe(II) circulation and provides insights into sustainable Fenton oxidation driven by metal-free catalysis.

Spatial-temporal Change and Driving Force of Carbon Storage in Three-River-Source National Park Based on PLUS-InVEST-Geodector Model

Exploring the spatial-temporal changes, driving forces, and future development tendency of the carbon sequestration service function of the Three-River-Source National Park ecosystem has great significance for regional ecological protection and sustainable development. Historical land-use data of Three-River-Source National Park from 1990 to 2020 were selected at five-year intervals, and based on the PLUS-InVEST-Geodector model, the spatial-temporal changes of historical carbon storage were analyzed, and the driving forces of spatial-temporal variation were explored combined with multiple factors. The carbon storage of Three-River-Source National Park in 2030 was predicted under the scenarios of natural development and ecological protection. The results showed that： ① The carbon storage of Three-River-Source National Park showed a fluctuating characteristic of increase-decrease-increase-decrease from 1990 to 2020, the carbon storage was increased by 41.85×106 t overall, and the grassland took the largest contribution. ② The spatial distribution characteristics of carbon storage in Three-River-Source National Park had little change between 1990 to 2020, and the evolution of the spatial distribution was relatively stable. The contribution ratio of the Yangtze River source park, Lancang River source park, and Yellow River source park was 7∶1∶2, which was roughly equivalent to the park area. ③ The major driving factors of the spatial-temporal variation of carbon storage in Three-River-Source National Park from 1990 to 2020 were： FVC, soil type, and annual precipitation. The interactive detection of each driving factor showed dual-factor enhancement and nonlinear enhancement. ④ The carbon storage of Three-River-Source National Park was predicted to decrease by 4.87% and 3.98% from 2020 to 2030 under the scenarios of natural development and ecological protection, respectively, and the carbon storage reduction under the ecological protection scenario had a significant inhibitory effect. The findings can provide data support for national spatial planning of Three-River-Source National Park and the enhancement of terrestrial ecosystem carbon storage.

Novel Catalyst-free Activation of Chlorine by Visible Light for Micropollutant Abatement

This study systematically investigated the direct activation of chlorine by visible light emitting diode (Vis-LED). Vis-LED could effectively activate chlorine to degrade micropollutants with degradation efficiency and pseudo-first-order degradation rate constant range of 64.3%-100% and 0.0340-0.195min-1, respectively. Quenching experiments and modeling results suggested that reactive chlorine species (RCS, including ClO•, Cl2•-, and Cl•) and hydroxyl radical (•OH) were involved in the degradation of atenolol (ATL). The contribution ratio of ClO•, free available chlorine, Cl•, Cl2•-, and •OH to ATL degradation were 58.7%, 17.4%, 15.6%, 1.8%, and 5.9%, respectively, in Vis-LED448/chlorine process. Moreover, the innate quantum yields of HClO and ClO- decreased from 0.229 and 0.0206 to 0.0489 and 0.0109mol·Einstein-1, respectively, as the wavelength increased from 448 to 513nm, leading to a decrease in ATL degradation, which was consistent with the model results. Experimental and modeling results have confirmed that ATL degradation decreased when pH increased from 4.0 to 9.0. Cl- had little effect on the degradation of ATL, while HA and HCO3- affected ATL degradation by scavenging reactive species and/or shielding effect. The concentration of disinfection by-products decreased with the increase of wavelength and pH. In summary, Vis-LED/chlorine is an efficient water treatment process even without a catalyst.

Die Effekte einer Lohnnebenkostensenkung für die Volkswirtschaft und die Wettbewerbsfähigkeit

Abstract The tax and social contribution ratio in Austria is very high by European standards, taxes on income in particular. This is reflected in a very wide tax wedge between labour costs and net income. The particularly high inflation in Austria in recent years has led to high wage increases and a loss of competitiveness. Based on a model analysis, it is shown that a reduction of taxes on the wage-sum by 1.4 % of GDP dampens the development of wage costs and increases employment by around 0.9 % or 40,000 persons. In addition, the reform reduces the GDP deflator by 0.9 to 0.7 percentage points and implies an increase in the real export volume by 1.4 % in the first three years.

Collaborative train timetabling and passenger flow control in oversaturated metro lines considering state-dependence

Congestion downgrades the moving speed of passengers in trains and platforms. This in turn affects congestion. That is, the moving speed of passengers interacts with congestion. It is state-dependent and obeys the fundamental diagram. This interaction makes the system unstable and can result in substantial passenger delays and heightened security risks in oversaturated metro lines. This study aims to rectify this by developing a more realistic collaborative optimization approach. Firstly, we formulate a deterministic fluid queuing network model to accurately capture the dynamic propagation of congestion in oversaturated metro lines. This model incorporates the fundamental diagram, thereby effectively considering the interaction between passenger movement speeds and congestion. A recursive algorithm is devised to solve the fluid queuing network model. The complexity of the algorithm is independent of the capacities of the stations and trains. This provides the possibility of analyzing large-scale metro networks. Based on the queuing network model, a mixed-integer nonlinear programming model aimed at minimizing the total passenger waiting time is built. To solve the model effectively, we employ an alternating direction method of multipliers framework to decompose the model into nonlinear programming and integer nonlinear programming problems, which are respectively solved by improved simultaneous perturbation stochastic approximation and adaptive large neighborhood search algorithms. Finally, a small-scale case and a real-world case with data from Chengdu metro lines are implemented to demonstrate the performance and effectiveness of the proposed approach. The experimental results provide some interesting insights. (1) Without consideration of state-dependence, the queuing model underestimates the passenger waiting time and overestimates the service levels. (2) As demand increases, excluding extreme oversaturation scenarios, the optimized results of the state-independent model progressively deteriorate compared to our state-dependent model, with the largest percentage decline being 50.23%. This is especially noticeable when the train capacity is limited. (3) The contribution ratio of passenger flow control in mitigating congestion gradually surpasses that of train timetabling with increasing demand. In the small-scale case, the former contribution ratio to optimization rises from negligible to 98.19%.

Century‐Long Variations in Surface Incident Solar Radiation Over Japan——Characterized by Observations and Reanalyses

ABSTRACTSurface incident solar radiation (Rs) is of great importance in determining the energy balance in the Earth system. In this study, we use century‐long homogenized observations over Japan to constrain five 20th century reanalyses to explore their performance in reproducing Rs variation on different time scales (high‐frequency components [HFCs], for signals with cycles less than 10 years; low‐frequency components [LFCs], for signals with cycles more than 10 years) by ensemble empirical mode decomposition (EEMD) method and to quantify the impact factors on the Rs estimations by the sum of tree (SOT) model. It is found that ERA20C, ERA20CM and CERA20C overestimated Rs by 0.48–1.49 W/m−2, while 20CRv2c and 20CRv3 underestimated Rs by −0.63 and −1.18 W/m−2, respectively for 1931–2010. Poor correlation coefficient (R) was found to be 0.10 for ERA20CM and 0.22 for 20CRv2c. 20CRv2c failed for 1931–1960 but improved considerably for 1961–2010. 20CRv3 uses an upgraded model and assimilates more observations compared with its predecessor 20CRv2c; however, only the original components and HFCs in Rs were improved, with nearly no improvement in the LFCs. In general, CERA20C Rs, with small biases and higher R of 0.73 for original signals, 0.83 for HFCs and LFCs, is superior to other reanalyses. No obvious trend in clear sky Rs demonstrated that reanalysed Rs are insensitive to the aerosol forcings. Therefore, cloud cover and water vapour maybe the main factors influenced reanalysed Rs. Most of time, Rs is more sensitive to cloud cover than vapour pressure for all reanalyses except original signals (with contribution ratio of 0.29 for cloud cover and 0.71 for vapour pressure) and LFCs (with contribution ratio of 0.41 for cloud cover and 0.59 for vapour pressure) in CERA20C, and original signals (with contribution ratio of 0.37 for cloud cover and 0.63 for vapour pressure) in ERA20C. This work pointed out that aerosol related processes such as aerosol forcings or aerosol radiative effect in reanalyses should be improved in the future, which will ultimately improve the interaction between aerosol and cloud in Rs simulations.

Identifying the bottleneck and its shifts for the nexus across water supply, power generation and environment systems: Hehuang, China

Identifying the bottleneck is the key to alerting and preventing unexpected failures of the nexus across water supply, power generation, and environment (WPE) systems. However, the bottleneck identification is challenged by the unclear concept of bottleneck as well as the difficulty of simulating complex emergent behaviors. Here, we develop a generic framework for identifying the bottleneck for the WPE nexus, which is defined as the subsystem that has the highest risk of leading to the failure of WPE nexus. First, the evolution of uncertainties of the state variables of WPE nexus is simulated by a generic stochastic dynamical system. Next, the propagation matrix, accumulation ratio (AR), and risk contribution ratio are defined as effective metrics and tools to identify the system bottleneck. Finally, the effects of human decisions and input stochasticity on the shifts of bottleneck are analyzed using sensitivity and scenario analysis. The WPE system in Hehuang Region, China, is selected as a case study. Results indicate that: (a) The effects of human decisions on ARs can be superimposed, suggesting a “superimposition method” for policy-making of Hehuang Region; (b) The subsystems can be classified as “endogenous” or “exogenous”, depending on the sources of accumulated uncertainties that are from local inputs, or inputs from the other subsystems; (c) There exist multiple bottlenecks at the same time that could shift from one subsystem to another, which complicates the prevention of the failures of WPE nexus. For the Hehuang Region, water and energy subsystems are more likely to be bottlenecks at the beginning stage, while society and environment subsystems are more likely to be bottlenecks at the steady stage. This study provides the first attempt to identify the bottleneck within the WPE nexus, which helps to provide realistic insights for preventing unexpected failures.

Source-specific ecological and human health risk analysis of topsoil heavy metals in urban greenspace: a case study from Tianshui City, northwest China.

Soil contamination of heavy metals in urban greenspaces can exert detrimental impacts on ecological biodiversity and the health of inhabitants through cross-media migration-induced risks. Here, a total of 72 topsoil samples were collected from greenspaces in the popular tourist city of Tianshui, ranging from areas with parks, residential, road, industrial and educational soils. The study aimed to evaluate an integrated source-specific ecological and human health risk assessment of heavy metals. Among the analyzed heavy metals, except Cr (mean), all exceeded the local background values by 1.30-5.67-fold, and Hg, Cd, Pb and As were the metals with large CV values. The Igeo and CF results showed Hg, Cd, As and Pb exhibited significantly high pollution levels and were the primary pollution factors. The mean PLI values indicated moderate pollution in educational (2.21), industrial (2.07), and road (2.02) soils but slight pollution in park (1.84) and residential (1.39) greenspaces. The Igeo, CF, and PLI results also revealing that these heavy metals are more likely to be affected by human activity. Four primary source factors were identified based on PMF model: coal combustion (25.57%), agricultural sources (14.49%), atmospheric deposition (20.44%) and mixed sources (39.50%). In terms of ecological risk, the mean IRI values showed considerable risks in educational soils (287.52) and moderate risks in road (215.09), park (151.27) and residential (136.71) soils. And the contribution ratio of atmospheric deposition for park, residential, road, industrial and educational greenspaces were 57.72%, 65.41%, 67.69%, 59.60% and 75.76%, respectively. In terms of human health risk, the HI (below 1) and CR (below 1.00E-04) for adults from soils of all land use types was negligible. However, children have more significant non-carcinogenic and carcinogenic hazards especially in residential soils, the HI (above 1) and CR (above 1.00E-04) revealed the significance of regarding legacy As contamination from coal combustion when formulating risk mitigation strategies in this area. The proposed method for source and risk identification makes the multifaceted concerns of pollution and the different relevant risks into a concrete decision-making process, providing robust support for soil contamination control.

Numerical Study on the Lateral Load Response of Offshore Monopile Foundations in Clay: Effect of Slenderness Ratio

To meet growing energy demands, offshore wind turbines (OWTs) with higher energy outputs are being developed, presenting increased challenges for their foundation design. Over the past decade, extensive research on the design optimization of OWT support structures has significantly reduced the anticipated costs of offshore wind farm development. Various design methods have been developed and applied in practice, each with its own advantages and limitations. In this study, 3D finite element (FE) modeling, validated against the measured response of a large-scale test monopile, is used to investigate the lateral load response of monopiles with different geometries and slenderness ratios in smaall and large displacements. The results are compared to the standard p–y method, and specific behavioral and design aspects of large-diameter monopiles, such as the moment contribution ratio from different resisting components and the minimum embedment length criteria, are evaluated and discussed. The results showed that the maximum and minimum differences between the 3D FE modeling and one-dimensional (1D) DNV p–y method are 41% and 11% for large displacements, and 32.5% and 13.3% for small displacements, respectively. As the slenderness ratio increases, the discrepancy between the finite element (FE) modeling results and the 1D DNV p–y method decreases, with an average difference of about 13% across all monopile diameters at an L/D ratio of 10, in both small and large displacements, indicating the reasonable accuracy of the 1D method for slenderness ratios of 10 and above. Among the three minimum embedment length criteria examined, the DNV recommended and vertical-tangent criteria offered shorter embedment lengths. The primary resisting moment across all slenderness ratios comes from the distributed lateral load along the monopile shaft (MCRp−y), which increases as the L/D ratio increases.

Mediating function of heart failure in the causal relationship between diastolic blood pressure and hypertensive renal disease with renal failure: a mediated Mendelian randomization study†

Abstract Objective To study the causality relationship between diastolic blood pressure (DBP) and hypertensive renal disease with renal failure (HRDRF) and the mediating role of heart failure (HF) in the causality relationship by network Mendelian randomization (MR). Methods Genome-wide analysis of DBP, HRDRF, and HF was downloaded from the public database (Genome-Wide Analysis Study [GWAS]) and was used to analyze the results and to conduct mediated MR analysis. Results Analysis showed that DBP was positively correlated with HRDRF (OR = 1.0002, 95% CI: 1.0001–1.0003, P = 1.8076e–05) and DBP was positively correlated with HF (OR = 1.0295, 95% CI: 1.0221–1.0370, P = 2.5292e–15). HF and HRDRF had a positive causal effect (OR = 1.0001, 95% CI: 1.0000–1.0001, P = 0.0152). Mediation analysis showed that the contribution ratio of HF to the combined effect of DBP and HRDRF was 24.69%. Conclusions DBP can increase the risk of renal disease with renal failure, and HF may play an important role in mediating this causal relationship.

Effect of cold expansion on the fatigue life of multi-hole 7075-T6 aluminum alloy structures under the pre-corrosion condition

The multi-hole structures with cold expansion are extensively utilized in the various joint parts of aircraft. However, the synergistic effect of stress concentration and atmospheric corrosion will cause severe deterioration of structural loading capabilities. Thus, it is crucial to investigate the fatigue life degradation mechanism of these structures under pre-corrosion conditions. In this paper, three-hole specimens with cold expansion (CE) and non-cold expansion (NCE) were used to investigate the effect of cold expansion on the fatigue performance of multi-hole structures of 7075-T6 aluminum alloy under pre-corrosion conditions. The life degradation law and damage mechanism of these two types of specimens under pre-corrosion conditions were analyzed. Furthermore, the cold expansion strengthening factor was proposed through the curve-fitting of the fatigue life attenuation ratio of these two types of specimens. Finally, a competition mechanism for the contribution ratio to the final fracture of the specimens in corrosive environments was proposed based on the SEM morphology analysis of the fatigue fracture of the specimens.

Significant contribution of amino acids to antioxidant capacity of Japanese rice wine (sake).

Various antioxidant components have been reported in Japanese rice wine (sake), while the contribution ratio of each component to the antioxidant capacity of whole sake has not been well understood. In this study, we evaluated the radical absorption capacity (H-ORAC and/or DPPH radical scavenging ability) and antioxidant components of commercially available sake, and estimated the major components contributing to antioxidant capacity. Water-soluble components with a molecular weight of less than 3000 contributed more than 90% to H-ORAC of sake by measuring the ultrafiltered fraction. The Maillard reaction seemed to have little influence on H-ORAC by browning experiments. The radical absorption capacity of sake showed a strong positive correlation with the amounts of four antioxidant amino acids (Cys, Met, Tyr, Trp) and two phenolic acids (ferulic acid and p-coumaric acid). Evaluating H-ORAC of a sake model solution composed of these antioxidants revealed that the four amino acids showed a clearly higher contribution (25.7-58.2%) than the phenolic acids. In addition, there was a slight synergistic effect when the four amino acids were mixed, whereas such effects were not seen when mixed with the phenolic acids and other sake major components (organic acids, glucose and ethanol). We concluded that the contribution of free amino acids to the radical absorption capacity is quite important in sake. These findings will provide a new perspective for antioxidant researches of sake and many fermented foods. © 2024 Society of Chemical Industry.

RBFsim – A tool for early planning stage of riverbank filtration systems

Riverbank filtration (RBF) is increasingly being considered an effective method to support the management of water supply and the management of groundwater-river water exchange. Literature, however, provides very limited methods for the initial evaluation of the RBF system. Specifically, initial evaluations need to rely on limited data, be cost-effective, and provide sufficient useful output. The paper provides the development of a tool called RBFsim, designed for the early assessment of flow hydraulics in a riverbank filtration (RBF) scheme during site selection and optimization of well operation. The developed tool allows simplified computation (based on the Analytical Element Method or AEM) of the flow field for single and multiple wells in a 2D homogeneous and isotropic aquifer with uniform flow. The tool superimposes analytical solutions for key RBF quantities such as residence time (the time required for river water to reach the well) and the proportions of water (contributed by the river and groundwater) in the well discharge. These solutions are superimposed on the developed flow field. Additionally, the tool can be used to evaluate the impact of riverbed clogging on the operation of the RBF system. The simplified computation due to AEM and limited data requirements allows the tool to be used in handheld (smartphones) or desktop devices with or without internet connection. RBFsim results are verified by comparing them with results from MODFLOW and MODPATH simulations, which are based on entirely different (finite difference) computational schemes. The obtained results from both these models match within the error margin of less than 5%. Further, the practicality and applicability of RBFsim are illustrated using synthetic and field data. While the tool provides a matching river water contribution ratio with field data, it demonstrates the best-fit residence times primarily for higher well discharge rates. These limitations are attributed to complexities observed in the field, such as a heterogeneous aquifer and nonuniform flow. Overall, the developed tool simplifies the complex computations required, particularly for assessing the feasibility and risk of RBF schemes. The developed tool’s methods and code are open-sourced (licensed under CC-BY 4.0), which promotes personalized modifications and extensions.

Cost Volume Profit Analysis as a Profit Planning Tool at Buket Husnul

UMKM Buket Husnul is a business in the creative industry that sells products in the form of flower bouquets with various models. In its profit planning Buket Husnul does not yet have a planning tool, therefore this study discusses related to profit planning at UMKM Buket Husnul which utilizes Cost-Volume-Profit analysis as a tool to plan its profits. Cost-Volume-Profit analysis is a very good profit planning tool to help business people make decisions in order to optimize their business profits. In this study, researchers used a type of research with descriptive qualitative methods, based on data sources from interviews and direct observation in the field. The research results of the cost volume profit analysis that have been carried out are for the contribution margin of Rp43,125,000.00 with a contribution ratio of 52%. In order to reach the break-even point or Break-Event- Point the business owner must be able to sell a bouquet of 1,100 units with an income of Rp. 8,269,231.00 per quarter so that the business does not get a loss, with the maximum Margin of Safety that can only decrease by Rp. 74,230,769.00 with a ratio of 89.98% and the results of Operating-Leverage of 1.12 times operating profit.

Variation of nitrate sources affected by precipitation with different intensities in groundwater in the piedmont plain area of alluvial-pluvial fan

A substantial reservoir of nitrogen (N) in soil poses a threat to the quality and safety of shallow groundwater, especially under extreme precipitation that hastens nitrogen leaching into groundwater. However, the specific impact of varying precipitation intensities on the concentration and sources of nitrate (NO3−) in groundwater across diverse hydrogeological zones and land uses remains unclear. This study aims to elucidate the fluctuations in NO3− concentration, sources, and controlling factors in shallow groundwater under different intensities of precipitation (extreme heavy precipitation and continuous heavy precipitation) in a typical alluvial-pluvial fan of the North China Plain by using stable isotopes (δ2H–H2O, δ18O–H2O, δ15N–NO3-, δ18O–NO3-), hydrochemical analyses and the SIAR model. Affected by extreme heavy precipitation the depleted isotopes of δ2H–H2O and δ18O–H2O in groundwater of the entire area suggested the rapid recharge of fast flow by precipitation. The enriched isotopes of δ2H–H2O and δ18O–H2O of north part in alluvial fan after continuous heavy precipitation showed the recharge of translatory flow of soil water. NO3−concentrations increased to 78.9 mg/L after extreme heavy precipitation and increased to 105.3 mg/L after continuous heavy precipitation when compared to those in normal year (56.8 mg/L) of north part of the alluvial fan. However, NO3− concentrations had slight variation after continuous heavy precipitation of south part of the fan due to the deep vadose zone. The contribution ratio of sources of NO3− in groundwater by using SIAR analysis revealed manure & sewage (MS) as the primary NO3− source (accounting for 59.7–78.1%) before extreme heavy precipitation, chemical fertilizer (CF) making a minor contribution (6.9–17.3%). Different precipitation events and land use types lead to changes in NO3− sources. Affected by extreme heavy precipitation, the contribution of MS decreased while CF increased, particularly in vegetables (26.2–28.1%) and farmland (29.2–34.7%). After continuous heavy precipitation, MS increased again, particularly in vegetables (50.0%) and farmlands (20.4–66.4%), with CF either increasing or remaining steady. This indicated that continuous heavy precipitation accelerated the leaching of nitrogen (organic manure application) stored in deep soil to groundwater and it has a larger influence on the increasing of NO3− concentrations of groundwater than extreme heavy precipitation which carried nitrogen (chemical fertilizer application) in shallow soil to groundwater by fast flow. These findings underscore the importance of considering soil chemical N stores and their implications for groundwater contamination mitigation under future extreme climate scenarios, particularly in agricultural management practices.

Mechanism and bearing load-capacity of compound stirrup UHPC-encased CFST columns under axial compression

To augment the synergistic performance between the outer reinforced concrete and the core concrete-filled steel tube (CFST) in standard reinforced concrete encased CFST columns, 14 columns underwent axial compression testing. Of these, 12 columns were encased with compound stirrup Ultra-High Performance Concrete (UHPC), one with compound stirrup high-strength cement-based material, and one with ordinary reinforced concrete. The experiment investigated the effects of compound stirrup forms, stirrup spacing, steel fiber content, steel tube wall thickness, outer concrete types, and core concrete strength on the final failure mode, load-displacement curve, strain characteristics, and development pattern of the specimens. Results indicated improved deformation coordination between the outer compound stirrup UHPC and the core CFST in compound stirrup UHPC encased CFST columns. The yield strength of both the compound stirrup and the steel tube was fully developed within the tested parameter range. A calculation method considering the compound stirrups, fiber constrained outer concrete, and the CFST’s contribution ratio was used to predict the ultimate bearing capacity of reinforced concrete encased CFST columns.

Tool wear prediction based on kernel principal component analysis and least square support vector machine

Abstract To accurately predict the amount of tool wear in the machining process, a monitoring model of tool wear based on multi-sensor information feature fusion is proposed. First, by collecting the cutting force, vibration, and acoustic emission signals of the tool during the whole life cycle, the multi-domain characteristics of the signal are extracted; then, kernel principal component analysis is used to reduce the dimensionality of the extracted data, and the principal components whose cumulative contribution ratio exceeds 85% are obtained. The redundant features with little correlation with tool wear were removed from the feature vectors to generate the fusion features. Finally, the fusion features are input into the least squares support vector machine model optimized by particle swarm algorithm for regression prediction of tool wear. The non-linear mapping relationship between the physical signal and the tool wear is discovered, which effectively realizes the prediction of the tool wear. Compared with the existing tool wear prediction methods, the method proposed has higher prediction accuracy.

Interaction and compatibility between steel and concrete of circular CFST stub columns with high-strength materials

To promote the application of high-strength-materials in concrete-filled steel tubular (CFST) columns, finite element modeling, and parametric analysis were conducted on circular CFST stub columns filled with normal-strength concrete (NSC) and ultra-high strength concrete (UHSC). For simulating properties of concrete under passive confinement, a three-dimensional constitutive model for NSC and UHSC was established, of which the stress-strain relation and evolution of dilation angle are both related to confining pressure and axial plastic strain. The model was verified by tests of CFHSST (concrete-filled high-strength steel tube) and UHSCFST (ultra-high-strength concrete-filled steel tube), demonstrating that the interaction between concrete and steel tube can be revealed correctly. Parameter analysis of CFST stub columns filled with NSC and UHSC was carried out, with the grade of steel tube covering from Q235 to Q890 and the D/t ratio ranging from 8.9 to 75. With the decrease of D/t ratio, the deformation capacity and post-peak performance of columns are improved. A recommended range of steel contribution ratio of UHSCFST was proposed for the consideration of cost and safety, which is 25% ∼ 63%. Based on the analysis of interaction between concrete and steel tubes, the compatibility of the two materials is recommended, of which the yield of steel tube occurs after contact with concrete and before the concrete reaches its peak strength. Besides, the formula in EC4 overestimates the load-bearing capacity of CFST stub columns with high-strength materials. Therefore, a modified formula was proposed that reduces the enhancement factor of concrete strength and enables a safer prediction of load-bearing capacity.

Optimization of an Aerospace Bracket by Additive Manufacturing with Continuous Fiber Reinforced Plastics

Fused Deposition Modelling (FDM), one of the most widely used methods of Additive Manufacturing Technique known as 3D Printing, is a popular technique used to produce different engineering components using common engineering fibre. Carbon fibre filament. This study presents an experimental study examining the effect of printing parameters on the mechanical properties of components produced with Carbon fibre filaments. The effects of the printing parameters determined as infill pattern, infill density and nozzle temperature on the mechanical strength parameter determined as tensile strength and flexural strength of Carbon fibre samples produced in standard sizes were investigated experimentally. The experimental design was carried out in accordance with the Taguchi L9 orthogonal array, and the relationship between the printing parameters and the mechanical strength parameters was modelled mathematically. The predicted strength values calculated using mathematical models were compared with the experimental test results. The results showed that the tensile strength and flexural strength values were directly proportional to the infill density. Experiments have shown that the most effective 3D printing parameter on the mechanical strength parameters is the infill density parameter with a contribution ratio of 62.09% for tensile strength and 72.83% for flexural strength. As a result of the RSM optimization, it was determined that the infill density 60%, the nozzle temperature value 265 C° and the infill pattern type lines to maximize the flexural strength and tensile strength values. Key Words: Sustainable Material, 3D Printing Parameters, Mechanical Strength Optimization, Response Surface Methodology.

Extremely high wall pressure events in shock wave and turbulent boundary layer interactions using DNS data

This study investigates high-amplitude Extreme Wall Pressure fluctuation Events (EWPEs) in Shock wave/Turbulent Boundary Layer Interactions (STBLIs) through the conditional sampling of direct numerical simulation databases. The aim is to evaluate the effect of STBLIs and their strength on the statistical properties and associated turbulent structures of EWPEs using the conditional-averaging and clustering method. The temporal statistical results show that the occurrence probability and contribution ratio of EWPEs decrease downstream of strong STBLI, but their duration and interval time increase. Regarding two-dimensional wall pressure structures, the large population of small-scale structures becomes more elongated, but strong interactions induce a greater number of large-scale structures. The pairing of wall pressure events with a higher occurrence probability is verified by the joint probability density functions. Conditional analysis reveals that, as the interaction strength increases, the ejection motion associated with positive events occurs farther downstream and the spanwise vortex core locating above negative events is lifted up along the wall-normal direction. Moreover, analysis associates the paired wall pressure events with the sweep, ejection, and swirl motions in STBLIs, where hairpin eddies play an important role in the formation of positive–negative paired wall pressure structures.