Time-varying Effects Research Articles

Pengaruh Waktu Tinggal Kadar COD, BOD, TSS dan Amonia Pada Limbah Cair Industri Tekstil dengan Metode Constructed Wetland Menggunakan Tanaman Melati Air (Echinodorus Palaefolius)

Textile waste has damaged the environment with various very high pollutants, such as high dissolved solids, COD, BOD, TSS and Ammonia. The high pollutant load in textile waste causes damage to aquatic ecosystems and affects human health if not managed properly. Constructed wetland is one of the efficient, effective and appropriate liquid waste treatment technologies because it uses a variety of vegetation. The study of the constructed wetland system using water jasmine plants (Echinodorus palaefolius) aims to reduce COD, BOD, TSS and Ammonia pollutants as an effect of detention time variations. Detention time includes 3,5,7 days. The results of the study showed that COD, BOD, TSS and Ammonia levels were affected by detention time. The efficiency of reducing COD levels on days 3, 5, and 7 was 58.38%, 54.30% and 55.45% respectively with concentrations of 397 mg/L, 430 mg/L and 425 mg/L. At BOD levels of 5.12%, 9.40% and 47.69% with concentrations of 111 mg/L, 106 mg/L and 61.2 mg/L. At TSS levels of 54.96%, 60.30% and 63.35% with concentrations of 59 mg/L, 52 mg/L and 48 mg/L. At Ammonia levels of 49.30%, 49.65% and 56.25% with concentrations of 1.46 mg/L, 1.45 mg/L and 1.26 mg/L. The results of textile wastewater quality standards are in accordance with the Minister of Environment Regulation No. 5 of 2014.

Seismic performance of continuous rigid-frame bridges affected by flood-induced scour

River-crossing bridges in high-intensity seismic regions can be vulnerable to the combined action of earthquake and flood hazards; in particular, flood-induced scour of the substructure can have a notable influence on the seismic behavior of bridge structures. Currently, long-span continuous rigid-frame bridges are widely used to cross large rivers worldwide, yet related studies on their seismic performance under flood-induced scour have been lacking. This paper focuses on the effects of time-varying flood-induced scour on the seismic performance of long-span continuous rigid-frame bridges incorporating complex thin-walled reinforced concrete piers with pile group foundations. A detailed finite element (FE) model for a representative bridge structure is developed and the scour depth risk of the bridge is evaluated under several flood events for different return periods. The influence of flood-induced scour on the pile-soil interaction is examined throughout the bridge service life. Detailed seismic fragility assessment is carried out through nonlinear time-history analyses using a large suite of 100 seismic records. Particular focus is given to evaluate the time-varying scour effects on the pile and soil deformations as well as on the component and system level seismic fragility functions. It is shown that the total flood-induced scour depth exhibits a nonlinear increasing trend with the increase in service time, particularly in the initial 10 years of the bridge service life. The deformations of the scoured piles, within a depth of 20 m, are also shown to increase significantly with the increase in service time. The results indicate that the scour has a pronounced effect on both the component and system level seismic fragility functions. Importantly, although the piles (or pile groups) are typically designed to remain elastic under seismic loading, they are shown to be subjected to significant inelastic demands and governing damage levels as a result of time-varying flood-induced scour effect. Overall, this study provides a methodology to assess the time-varying seismic fragility of the scoured long-span rigid-frame bridges with complex thin-walled reinforced concrete piers, which can enhance the multi-hazard time-varying seismic resilience assessment for bridge structures with similar configurations.

Time-Varying Spillover Effects of Carbon Prices on China’s Financial Risks

As China’s financial markets become increasingly integrated and the carbon market undergoes financialization, the impact of carbon emission price fluctuations on financial markets has emerged as a key area of systemic risk research. This study employs the Generalized AutoRegressive Conditional Heteroskedasticity (GARCH) model and the optimal Copula function to investigate the dynamic correlation between carbon prices and China’s financial markets. Building on this, the Monte Carlo simulation and Copula CoVaR models are used to explore the spillover effects of carbon price volatility on China’s financial markets. The findings reveal the following: (1) Carbon price fluctuations generate spillover effects on all financial markets, but the intensity varies across different markets. The foreign exchange market experiences the strongest spillover effect, followed by the bond market, while the stock and money markets are relatively less affected. (2) The optimal Copula functions differ between the carbon market and China’s financial markets, indicating heterogeneous characteristics across regional markets. (3) There is a degree of interdependence between the carbon market and various sub-markets in China’s financial system. The carbon market has the strongest positive correlation with the commodity market and a relatively high negative correlation with the real estate market. These findings underscore the importance of integrating carbon price volatility into financial risk management frameworks. For policymakers, it highlights the need to consider market stability measures when crafting carbon emission regulations. Market managers can leverage these insights to develop strategies that mitigate risk spillover effects, while investors can use this analysis to inform their portfolio diversification and risk assessment processes.

Causality, Connectedness, and Volatility pass-through among Energy-Metal-Stock-Carbon Markets: New Evidence from the EU

The EU carbon market serves as an innovative financial instrument with the primary objective of contributing to mitigating the impacts of climate change. This market demonstrates significant interconnectedness with fossil energy, precious metal, and financial markets, although limited research has focused on the causality, dependency, intensity and direction of time-varying spillover effects. This study examines how the energy, metal, and financial markets have an impact on the EU carbon market. It focuses on three main research questions, namely: 1) how do these markets affect each other?; 2) how do they connect?; 3) how do volatilities spillover among them? By answering these questions, the study aims to assist EU decision makers to develop effective carbon policies, help investors manage risks and promote practices that are consistent with the EU's climate goal. To achieve these objectives, this paper proposes a novel methodological approach that combines the most recent econometrics methods, such as Directed Acyclic Graph analysis, Canonical Vine Copula models, and Time-Varying parameter Vector Auto Regressive models with Stochastic Volatility with the use of a comprehensive sample of daily data from April 26, 2005 to December 31, 2022. The major findings of this study demonstrate that causality predominantly runs from energy, metal, and financial markets to the EU carbon market. The dependency structure, although varying across different sub-periods, shows a strong relationship observed between oil, coal, silver, copper, EuroStoxx600, and CO2 market. Additionally, the oil and copper futures prices exhibit the highest dependence on EUA prices. Furthermore, the study establishes that the EU carbon market is a net receiver of shocks from all other markets, with the energy, metal, and financial markets significantly influencing volatility in EUA prices. The time-varying spillover effect is most pronounced with a one-day lag, and the duration of the spillover effects ranges from 2 to 15 days, gradually diminishing over time. These results have the potential to increase the understanding of the EU carbon market and offer practical guidance for policymakers, investors, and companies involved in this domain.

Industrial designs and firm performance: evidence from publicly traded Canadian companies, 1990–2014

ABSTRACT Industrial designs (IDs) are a specialized type of intellectual property that protects a product's form and presentational features, giving it uniqueness that differentiates it from other products. This paper estimates the effect on firm revenue and profitability of holding IDs. Using a unique data set linking Canadian ID holdings with Canadian publicly traded firms over the years 1990-2014, the authors use two methods to identify a positive association between holding IDs and firm revenue per employee and net income per employee. We contribute to the literature on IDs by introducing controls for patenting, R&D spending, and time-varying sector effects. To determine the marginal effect of each additional ID held, we use a fixed effects regression and find that a 1% increase in the stock of IDs increases revenue per employee by 0.19%. With a nearest-neighbor matching approach, we find a 10% total premium in revenue per employee and a 20% premium in net income per employee among firms holding at least one ID, compared to those with none.

Life years lost by childhood cancer treatment and health related late effects among childhood cancer survivors

BackgroundIdentifying risk factors contributing the most to mortality of childhood cancer survivors is essential to guide harm reduction efforts in childhood cancer treatments, and long-term follow-up of childhood cancer survivors. MethodsWe assessed Life Years Lost from childhood cancer treatments and their health-related late effects among the French Childhood Cancer Survivors Study, a cohort of 7670 5-year childhood cancer survivors. Using a landmark strategy, we also assessed time-varying effects of risk factors, and how the multi-morbidity affects life years lost. ResultsWe found subsequent malignant neoplasm (9.0 years [95 %CI: 4.3–13.7]), severe cardiac disease (8.0 years [95 %CI: 1.2–14.9]), and the use of radiotherapy (6.0 years [95 %CI: 4.7–7.3]) to be the highest contributors to Life Years Lost among childhood cancer survivors. We found no interaction impact on life years lost between health related late effects considered. ConclusionsThose findings suggest that radiotherapy is the root cause of early mortality among childhood cancer survivors. Moreover patients experiencing a subsequent malignant neoplasm or a cardiac disease should be monitored closely after the event, as comorbidity is common and causes premature deaths.

The impact of microplastics on lake communities: A mesocosm study

Plastics are pervasive pollutants that are being produced at an increasing rate to meet consumer demands. After entering the environment, plastics can break down, creating smaller fragments, including secondary microplastics. Microplastic contamination in lakes has been recorded worldwide, and the ingestion of microplastics has been documented in zooplankton, macroinvertebrates, and fish. Microplastic ingestion and exposure can cause varying deleterious effects on these organism groups, but the impact of realistic microplastic concentrations on whole freshwater food webs requires further study. We addressed these knowledge gaps by conducting an 8-week experiment factorially crossing microplastic addition at a concentration of 1.5 particles/L with a fish predator (perch, Perca fluviatilus) presence in 1200-L outdoor mesocosms. Microplastic exposure had time-varying effects on zooplankton abundance, with a lower abundance of zooplankton in plastic treatments at the end of the experiment. Although microplastics had no impact on total macroinvertebrate abundance, there were effects on individual taxa. In the presence of microplastics, the cased caddisfly Triplectides spp. had a significantly lower abundance, which may have led to an increase in the snail Gyraulus spp. in week eight. Across the benthic and pelagic invertebrate communities, there were near-significant compositional differences between control and plastic treatments. These findings indicate that microplastic exposure may negatively impact freshwater invertebrate communities, even at low, field-realistic concentrations representative of the densities currently found in lakes.

Time-varying effects of macro shocks on cross-border capital flows in China's bond market

As the most innovative initiative for the liberalization of Chinese bond market, the Bond Connect program greatly promotes the participation of cross-border capitals. In this paper, by analyzing the changes in the number of foreign investors entering the market, the volume of bond trading and the total amount of bond holdings, we find that the Bond Connect has become the dominant platform for foreign investors to participate in the Chinese bond market. Besides, using a TVP-VAR model based on a set of monthly time-series data from July 2017 to September 2023, we identify the dynamic impacts of four macroeconomic shocks: bond market forces, economic growth forces, monetary policy shocks, and economic policy uncertainty, on net capital inflows into the Chinese bond market. The results indicate that all these macroeconomic forces significantly affect capital inflows, with bond market forces exerting the greatest impact. Moreover, the direction, magnitude, and trends of each macro factor's impact on net capital inflows exhibit distinct characteristics.

Appraising the corrosion inhibitory efficacy and adsorption mechanism of leaf extract of Datura discolor on low-carbon steel in low pH media via gravimetric experiments and AFM analysis

BackgroundThe study investigated the inhibitory action of Datura discolor leaf extract against the corrosion of low-carbon steel in 0.5 M solutions of three acids. The purpose was to ascertain the effect of extract concentration, immersion time and temperature variation on corrosion inhibitory efficiency, and to relate to existing reports which show that organic molecules in most plant extracts inhibit corrosion. Extraction of the leaves was done by maceration using methanol, and solvent was removed by evaporation to dryness. Classical gravimetric (mass loss) experiments were used, and experimental data were fitted to adsorption isotherm models to ascertain the best approximation. Surface examination of the low-carbon steel substrates was carried out using the atomic force microscope.ResultsInhibitory protective efficiency of extract was found to appreciate with increasing Datura discolor leaf extract concentration at a fixed temperature, with values ranging 77.6–88.8%, 91.35–98.08% and 19.64–44.64% in H2SO4, HCl and HNO3 solutions respectively at 27 °C. Elevation of temperature was found to depreciate the inhibitor efficiency at constant inhibitor concentration. Best isotherm model fitting was obtained with Langmuir model both at 27 °C and 60 °C and in all the hostile media, while Temkin model gave good approximation only at 60 °C and in H2SO4 and HCl solutions only. The negative values of free energy of adsorption (ΔGads0)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(\\Delta G_{{{\ ext{ads}}}}^{0} )$$\\end{document} suggested that the adsorptive interaction of the inhibitor with the substrate surface was very spontaneous. Values of ΔGads0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\Delta G_{{{\ ext{ads}}}}^{0}$$\\end{document} were all consistent, fluctuating between − 16.35 and − 17.63 kJ mol−1 in both H2SO4 and HCl solutions, and between − 9.76 and − 10.25 kJ mol−1 in HNO3 solution, and this suggests that adsorption of the inhibitor molecules occurred via physisorption. Values of the activation energy of the corrosion reaction (Eact)\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$(E_{{{\ ext{act}}}} )$$\\end{document} are all < 40 kJ mol−1, suggesting that the inhibition occurred by a physical adsorption mechanism.ConclusionsThe study concludes that Datura discolor crude leaf extract suppressed the corrosion reactions, and the inhibition was found to arise from the physisorptive interaction of the organic molecules with the substrate/solution interface, forming a stabilize inhibitor film on the substrate surface as revealed by the atomic force micrographs.

Time-varying effects of the oil prices to the stock returns in Turkiye

Time-varying effects of the oil prices to the stock returns in Turkiye

Trends in the association between alcohol use and generalized anxiety in Finnish adolescents

Abstract Background During the past two decades, alcohol use has decreased among adolescents, but on the contrary, anxiety symptoms have increased (at least among females). These diverging trends set interesting opportunities to examine whether the strength of the well-known correlation/co-occurrence between alcohol use and anxiety has also changed. This study aims to examine changes in the co-occurrence and associations between heavy episodic drinking (HED) and generalized anxiety among adolescents in Finland from 2013 to 2023. Methods Data from the Finnish School Health Promotion Study between 2013-2023 covered 874 110 participants aged 13-20. Generalized anxiety was measured using Generalized Anxiety Disorder Scale (GAD-7) (range 0-21), and heavy episodic drinking was measured as reported heavy drunkenness once a month or more often versus less than once a month. Yearly prevalence estimates of co-occurrence were analyzed for those with moderate to severe anxiety symptoms (&amp;gt;10) and monthly or more frequent HED. Associations between anxiety and HED were analyzed using logistic regression and time-varying effect modelling. Interactions between time and anxiety predicting HED were also considered. Results The moderate to severe anxiety symptoms increased from 10.7% to 20.9% and HED decreased from 18.0% to 11.8% between 2013 and 2023. The proportion of those with both HED and moderate to severe anxiety increased from 2.9% in 2013 to 3.6% in 2023. The association between anxiety symptoms and HED was stable during the study period, with odds ratios ranging between 1.06 and 1.07. Conclusions During the past decade, diverging trends in generalized anxiety symptoms and heavy episodic drinking have not changed the association between them. The proportion of adolescents with these co-occurring health concerns has increased in females. This calls for continuous efforts to strengthen the integration of mental health and substance use prevention and services. Key messages • The association between generalized anxiety and heavy episodic drinking has not changed in adolescents in Finland between 2013 and 2023. • The proportion of those with both moderate to severe anxiety symptoms and heavy episodic drinking has increased in females and remained stable in males during the past decade (2.9% - 3.6%).

Time-Varying Spillover Effects Between Clean and Traditional Energy Under Multiple Uncertainty Risk: Evidence from the U.S. Market

The global energy landscape is undergoing an unprecedented transformation with the rapid development of clean energy and the continued significance of traditional energy creating a complex dynamic relationship. This study employs the TVP-QVAR-DY model to systematically examine the dynamic spillover effects between clean and traditional energy markets in the United States, focusing on the impacts of economic policy uncertainty (EPU) and geopolitical risk (GPR). The findings reveal (1) significant time-varying spillover effects between the two markets, with total spillover effects ranging from 30% to 50%, intensifying during extreme events; (2) increases in EPU and GPR exacerbate uncertainty in energy markets, particularly in the traditional energy sector, with spillover effects from crude oil to natural gas reaching 23.60% and vice versa at 24.30%; and (3) in the short term, the clean energy market is influenced by traditional energy, with spillover effects from oil to clean energy at 5.10%, while in the medium to long term it gradually becomes independent and inversely affects the traditional energy market, contributing 2.94% to oil spillovers. The results indicate that as the global energy transition deepens, the clean energy market is shifting from a risk receiver to a risk contributor. Based on these findings, the study proposes policy recommendations including accelerating energy structure transition, managing macroeconomic uncertainty risks, coordinating domestic and international energy markets, and leveraging market mechanisms.

Effect of Mixing Time Variation and Framing Time on the Quality of Coffee Grounds-based Solid Soap

The increase in public consumption of coffee has resulted in an increase in wasted coffee grounds. Coffee grounds have good content for the skin, so they can be reused as a basic ingredient in soap-making. In the soap making process, the mixing and framing stages can affect the quality of the soap. This study aims to determine the effect of mixing time of 24.5 minutes, 25 minutes, and 25.5 minutes as well as framing time of 3 days, 5 days, and 7 days on the physical and chemical quality of solid soap made from coffee grounds. The physical quality parameters observed are colour, texture, cracking, and foam power. The chemical quality parameters are foam stability, pH, moisture content, and free alkali. The method used was the questionnaire method followed by statistical analysis using the Kruskal Wallis test for physical quality tests and the experimental method followed by statistical analysis using the Two-Way ANOVA test for chemical quality tests. The results showed that all variations in mixing time and framing time had an effect on the physical and chemical quality of solid soap and there were significant differences. The panellists assessed the physical quality of the soap to be attractive, hard, with no cracks, and foamy, while the results of the chemical quality test, the soap produced is safe to use by the quality standards of solid soap with a foam stability range of 82%-97%, pH 10.3-11.8, moisture content 6%-14%, and alkali free 0.03%-0.09%.

On the Effects of Physical Climate Risks on the Chinese Energy Sector

We examine the impact of physical climate risks on energy markets in China, distinguishing between traditional energy and new energy stock markets, and the energy commodity market, utilizing a time-varying parameter vector autoregressive model with stochastic volatility (TVP-SV-VAR). Specifically, we investigate the dynamic effects of five specific subtypes of physical climate risks, namely waterlogging by rain, drought, typhoon, cryogenic freezing, and high temperature, on WTI oil prices and coal prices. The findings reveal that these physical climate risks exhibit time-varying similar effects on the returns of traditional energy and new energy stocks, but heterogeneous effects on the returns of WTI oil prices and coal prices. Finally, we categorize and examine the impact of both acute and chronic physical risks on the energy commodity market.

Estimating Time-Varying Exposure Effects Through Continuous-Time Modelling in Mendelian Randomization.

Mendelian randomization is an instrumental variable method that utilizes genetic information to investigate the causal effect of a modifiable exposure on an outcome. In most cases, the exposure changes over time. Understanding the time-varying causal effect of the exposure can yield detailed insights into mechanistic effects and the potential impact of public health interventions. Recently, a growing number of Mendelian randomization studies have attempted to explore time-varying causal effects. However, the proposed approaches oversimplify temporal information and rely on overly restrictive structural assumptions, limiting their reliability in addressing time-varying causal problems. This article considers a novel approach to estimate time-varying effects through continuous-time modelling by combining functional principal component analysis and weak-instrument-robust techniques. Our method effectively utilizes available data without making strong structural assumptions and can be applied in general settings where the exposure measurements occur at different timepoints for different individuals. We demonstrate through simulations that our proposed method performs well in estimating time-varying effects and provides reliable inference when the time-varying effect form is correctly specified. The method could theoretically be used to estimate arbitrarily complex time-varying effects. However, there is a trade-off between model complexity and instrument strength. Estimating complex time-varying effects requires instruments that are unrealistically strong. We illustrate the application of this method in a case study examining the time-varying effects of systolic blood pressure on urea levels.

Are natural resource volatility curses or blessings for economic performance? Stories of resource-rich regions

This paper analyses the time-varying and non-linear effects of natural resource volatility on economic growth in 10 countries using the smooth transition regression (STR) model and further examines the long-run and short-run relationships using the autoregressive distributed lag (ARDL) cointegration approach. The conclusions exhibit that natural resource rents are linearly and non-linearly associated with economic growth in countries with different levels of economic development, and display long-term cointegration and short-term equilibrium state. This study provides guidance for policymakers to implement long-term and short-term management strategies when considering national development differences.

Life-cycle seismic performance of bridges with thin-walled steel piers under bi-directional excitations

In corrosive environments, steel bridges demonstrate time-dependent seismic performance and varied directional responses to bi-directional excitation at different life-cycle stages. However, current seismic assessment methods for bridges have not adequately addressed the time-dependent effects of bi-directional excitation directionality on seismic responses throughout their entire life cycle. Thus, this study aims to investigate the time-varying directional effects of bi-directional seismic excitations on steel bridges with multiple parameters and to propose a method for predicting the range of critical incident angles while considering the aging effects of bridges. Initially, time-dependent functions that characterize steel corrosion are integrated into multiscale finite element models of the steel bridges to simulate corrosion progression across their life-cycle stages. Subsequently, a quantitative analysis of the bi-directional seismic response of steel bridges is conducted throughout their life cycle, accounting for the directionality of seismic excitation. Finally, a method and process for predicting the range of time-varying bi-directional critical incident angles with 95 % probability are derived by fitting the statistical probability distribution boundary values of the critical incident angle deviation index. The study's findings indicate that the aging effects of steel bridges amplify the displacement response under bi-directional seismic excitation, with the maximum displacement response difference exceeds 40 %. The service time may increase the sensitivity of steel bridges to changes in incident angles, potentially amplifying the displacement response by a factor of 1.69. The study's findings highlight the importance of considering aging effects and bi-directional excitation directionality in bridge seismic assessments.

Evaluation on Preparation and Performance of a Low-Carbon Alkali-Activated Recycled Concrete under Different Cementitious Material Systems.

A green, low-carbon concrete is a top way to recycle waste in construction. This study uses industrial solid waste slag powder (S95) and fly ash (FA) as binders to completely replace cement. This study used recycled coarse aggregate (RCA) instead of natural coarse aggregate (NCA). This is to prepare alkali-activated recycled concrete (AARC) with different cementitious material systems. Alkali-activated concrete (AAC) mixtures are modified for strength and performance based on the mechanical qualities and durability of AARC. Also, the time-varying effects of the environment on AARC properties are explored. The results show that with the performance enhancement of RCA, the mechanical performance of AARC is significantly improved. As RCA's quality improves, so does AARC's compressive strength. At a cementitious material content of 550 kg/m3, AARC's 28d compressive strengths using I-, II-, and III-class RCA were reduced by 2.2%, 12.7%, and 21.8%, respectively. I-class AARC has characteristics similar to natural aggregate concrete (NAC) in terms of shrinkage, resistance to chloride penetration, carbonization, and frost resistance. AARC is a new type of green building material that uses industrial solid waste to prepare alkali-activated cementitious materials. It can effectively reduce the amount of cement and alleviate energy consumption. This is conducive to the reuse of resources, environmental protection, and sustainable development.

Innovative strategies for time-release PCE design and cement paste flowability control

Extending the retention time of cement paste flowability with the addition of admixtures containing slow-release components is standard practice for ensuring the continued building quality of cement-based materials. This study aims to control the release rate of PCE and enhance its time-varying dispersion effect in fresh cement paste by utilizing Time-dependent Release PCEs (TRPCEs) with varying side-chain structures. The structural characterization of the synthesized TRPCEs was investigated using GPC (Gel Permeation Chromatography), FTIR (Fourier Transform Infrared Spectroscopy), and 1H NMR (Proton Nuclear Magnetic Resonance) techniques. Furthermore, experiments were carried out on time-varying flowability with different dosages of TRPCEs to investigate the flowability changes under the time-varying release effect. The influence of TRPCEs on cement hydration was examined using isothermal calorimetry by measuring the early hydration heat of cement paste. The time-dependent adsorption behaviors of TRPCEs were also examined using a TOC (Total Organic Carbon) analyzer. The findings show that TRPCEs have a minor effect on the cement hydration process's rapid reaction period but little effect on its induction and acceleration periods because of variations in the initial dispersion effect. Additionally, the adsorption behaviors of TRPCEs on cement particles vary significantly due to the hydrolysis of slow-release groups. The varying adsorption and consumption of TRPCEs on cement particles and hydration products in different hydration phases are key controlling factors for the time-varying flowability changes in cement paste. Finally, this innovative approach offers a novel perspective for designing and preparing new types of PCEs with a strong capability for time-varying flowability retention.

Enhanced material removal modeling in cylindrical bonnet tool polishing: Incorporating time-dependent pad wear effects

To enhance the accuracy and stability of the material removal model for cylindrical bonnet tool polishing (CBTP), this study introduces a model incorporating the time-varying wear effect of the polishing pad. Initially, the functional principles of the CBTP method are systematically outlined. An advanced material removal model is then proposed, which accounts for the impact of pad wear on pressure and velocity distributions within the contact area. Experimental methods were employed to explore how pad wear affects the pad surface morphology, polishing quality, and material removal rates. Findings reveal that pad wear considerably influences both the depth of material removal and the quality of the polished surface. Validation experiments demonstrate that the enhanced model is accurate and stable. Including the time-varying factor, the discrepancy between the predicted and experimental values of the polishing spot size was 9.29 %, while the accuracy of the predicted material removal depth reached 90.74 %. Additionally, the removal profiles generated by the improved model closely matched those observed experimentally.