Weak Conditions Research Articles

Occurrence and risk assessment of p-phenylenediamines and their quinones in aquatic environment: From city wastewater to deep sea

p-Phenylenediamines (PPDs) and PPD-derived quinones (PPD-Qs) have been considered emerging pollutants recently. Their available data on sediment and sewage sludge are limited, especially the ecological risks. Here, typical PPDs and PPD-Qs were measured in the sludge of wastewater treatment plants and surface sediment of a developed river basin (including reservoirs, estuaries, and rivers) and deep-sea troughs. The total concentrations of PPDs (∑PPD) were highest in sludge (range: 9.06–248 ng g−1), followed by surface sediment of the Dongjiang River basin, China (3.33–85.3 ng g−1), and lowest in sediment of the Okinawa Trough (0.01–7.46 ng g−1). The median value of ∑PPD in surface sediment of rivers (9.54 ng g−1) was higher than those in reservoirs (4.28 ng g−1) and estuaries (5.26 ng g−1). N-(1,3-Dimethylbutyl)-N′-phenyl-p-phenylenediamine (6PPD) was the major congener in all samples, accounting for over 60 % of ∑PPD. For quinones, 6PPD-Q and IPPD-Q were frequently detected in sludge, only trace 6PPD-Q was detected in the sediment of estuaries (nd-0.62 ng g−1) and rivers (nd-5.24 ng g−1), and both of them were absent from the sediment of the Okinawa Trough. The occurrence of PPDs in the trough may be the in-situ release of microplastics, and due to the low-light and weak alkaline conditions of deep-sea water, quinones may hardly photodegrade from PPDs. The PPD concentrations in sludge were positively correlated with local GDP, and the annual PPD emission from sludge will exceed 1370 kg in China. The results of ecological risk assessments indicated low risks for PPDs in sludge-amended soil, median risks for several PPDs in river sediment, but median to high risks for 6PPD-Q contamination sludge-amended soil. For the first time, we explored the potential environmental risk of PPDs and related quinones in sludge used as a soil conditioner.

Towards a Sustainable Future: Examining the Symmetric and Asymmetric Effect of Unstable Macroeconomic Factors on Initial Public Offerings Variability

The research seeks to explore the symmetric and asymmetric effects of renewable energy, technological innovation, and ecological footprint on the variability of initial public offerings in the unique institutional setting of the Pakistani IPO market. The study used yearly data on the Pakistani IPO market and the macroeconomic variables from January 1992 to December 2020. Further, the study employed the linear and Non-Linear ARDL to investigate the symmetric and asymmetric nexus among variables. For that purpose, the stationarity of the variables was predetermined using Augmented Dicker Fuller (ADF) and Phillips Perron (PP) unit root tests. Additionally, the F-bound test verifies that IPO issuance and macroeconomic drivers are co-integrated. The findings show a symmetric and asymmetric relationship between IPO variability and macroeconomic variables under study. Renewable energy and technological innovation have statistically positive effects on IPO variability. On the contrary, the ecological footprint has a significantly negative impact on IPO variability. The weak condition of the Pakistani IPO market could be attributed to the slow adoption of technological innovation, the transition to renewable energy, and a high ecological footprint that attracts stringent regulatory and environmental compliance costs of going public.

Possible wormholes in f(R) gravity sourced by solitonic quantum wave and cold dark matter halos and their repulsive gravity effect

In this paper, we present new generalized wormhole (WH) solutions within the context of f(R) gravity. Specifically, we focus on f(R) gravitational theories formulated in the metric formalism, with our investigation centered on a power-law form represented by f(R)=ϵRχ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$f(R) = \\epsilon R^{\\chi }$$\\end{document}. Here, ϵ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\epsilon $$\\end{document} is an arbitrary constant, and χ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\chi $$\\end{document} is a real number. Notably, this form possesses the advantageous property of reducing to Einstein gravity when ϵ=1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\epsilon =1$$\\end{document} and χ=1\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\chi =1$$\\end{document}. To obtain these novel WH solutions, we establish the general field equations for any f(R) theory within the framework of Morris–Thorne spacetime, assuming metric coefficients that are independent of time. By utilizing an anisotropic matter source and a specific type of energy density associated with solitonic quantum wave (SQW) and cold dark matter (CDM) halos, we calculate two distinct WH solutions. We thoroughly investigate the properties of the exotic matter (ExoM) residing within the WH geometry and analyze the matter contents through energy conditions (ECs). Both analytical and graphical methods are employed in this analysis to examine the validity of different regions. Notably, the calculated shape functions for the WH geometry satisfy the necessary conditions in both scenarios, emphasizing their reliability. Our investigations into specific parameter ranges in both scenarios revealed the presence of ExoM. This ExoM is characterized by an energy–momentum tensor that violates the null energy condition (NEC) and, consequently, the weak energy condition as well, in the vicinity of the WH throats. Furthermore, we investigated the repulsive effect of gravity and discovered that its presence results in a negative deflection angle for photons following null geodesics. Importantly, we observed that the deflection angle consistently exhibits negative values across all r0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$r_0$$\\end{document} values in both scenarios, indicating the manifestation of the repulsive gravity effect. Finally, we compare the obtained WH solutions utilizing both distributions, as well as the f(R) power-law-like models, in order to assess the feasibility of energetic configurations for WHs within SQW and CDM systems.

Revisiting Weak Energy Condition and wormholes in Brans-Dicke gravity

It is known that the formation of a wormhole typically involves a violation of the Weak Energy Condition (WEC), but the reverse is not necessarily true. In the context of Brans-Dicke gravity, the generalized Campanelli-Lousto solution, which we shall unveil in this paper, demonstrates a WEC violation that coincides with the appearance of unbounded sheets of spacetime within the region where 0<r<rs. The emergence of a wormhole in the region where r>rs is thus only an indirect consequence of the WEC violation. Whereas the two regions, 0<r<rs and r>rs, in general are disconnected by physical singularities at r=rs, they are both part of the same mathematical solution, and their behavior can provide insights into the WEC, which is a mathematical property of the solution. Furthermore, we utilize the generalized Campanelli-Lousto solution to construct a Kruskal-Szekeres diagram, which exhibits a “gulf” sandwiched between the four quadrants in the diagram, a novel feature in Brans-Dicke gravity. Overall, our findings shed new light onto a complex interplay between the WEC and wormholes in the Brans-Dicke theory.

Stochastic fractional integrodifferential equations with jumps: application to an averaging principle

In this work we deal with a stochastic fractional integrodifferential equation associated to a Poisson random measure. We first prove existence and uniqueness of solution in the case of Lipschitz coefficients but also in the non Lipschitz case. In the second part, we establish an averaging principle in the sense of Khasminskii approach for a class of this equation with non lipschitz coefficients and weak averaging conditions.

Influence of surface texturing and coatings on mechanical properties and integration with bone tissue: an in silico study.

This investigation delves into the mechanical behaviour of titanium dental implants, a preferred choice for tooth replacement due to their superior reliability over alternative materials. The phenomenon of implant loosening, frequently induced by masticatory activities, underscores the significance of surface modification or texturing to bolster the interaction between the implant and bone tissue. This research comprehensively examines the effects of four distinct surface texturing techniques and five varied bone quality conditions on the biomechanical performance of these implants. The scope of this study is delineated by its focus on implants of diameters 4mm and 6mm, with lengths measuring 9mm and 12mm respectively. Furthermore, the analysis incorporates the evaluation of four different coatings-hydroxyapatite, HA3TO, HA3Sr, and HA1.5TO1.5Sr-to investigate their efficacy in enhancing the osseointegration process on textured surfaces of dental implants. The experimental design entails the assessment of stress distribution within the implant and its coatings, alongside the strain exerted on the surrounding cancellous bone, under the conditions of an average vertical biting force. A comparative analysis between solid implants and those subjected to surface texturing techniques has been conducted. This comparison elucidates the advantageous microstrain profiles presented by certain textured surfaces, which are deemed more conducive to optimal osseointegration. Notably, across all examined textures, the application of hydroxyapatite (HA) and a modified HA composition (HA1.5TO1.5Sr) demonstrates significant improvements in mechanical stability, particularly in scenarios involving weak and very weak bone conditions. This study's findings contribute to the ongoing advancement in dental implant technology, emphasizing the critical role of surface texturing and coating strategies in promoting implant longevity and integration within the biomechanical environment of the human oral cavity.

Modelling beach volume changes caused by moderate and weak hydrodynamic conditions

The goals of this study were the calibration of the XBeach model for moderate and weak hydrodynamic conditions in 2D mode and the determination of the volumetric changes induced by them. An evaluation of model performance was made based on the Brier Skill Score (BSS), the visual match of the profile shape (VMS), the absolute volumetric change error (m3/m) and the relative volumetric change error (%). An analysis of accuracy in determining volumetric changes in the dune coast, with XBeach applied, provided an average absolute error in determination of volumetric changes of 4.0 m3/m for a significant storm and 1.5 m3/m for moderate and weak hydrodynamic conditions in a 2D model calibration process. Simulations of morphological changes caused by moderate and weak hydrodynamic conditions for seven timeframes classified into three groups have been run in 2D mode. Within a validation process, the average absolute error in the determination of volumetric changes in the beach was ranging from 0.64 m3/m to 2.42 m3/m depending on the group of hydrodynamic conditions. A high value of the correlation coefficient (R) between the measured and modelled balance of volumetric changes (m3/m) for all timeframes – 0.79 and for the ‘strongest’ group no. 3 – 0.91 were revealed. For the remaining groups, i.e., group no. 1 and no. 2 of hydrodynamic conditions, no such correlation was observed. Furthermore, the temporal analysis of the sum of beach volumes proved that a rising trend was observed over 4 months. Thus, moderate and weak hydrodynamic conditions dominated the accumulation within the area of study. XBeach reflected this trend well, producing a difference between the measured and modelled sum of volumes at the end of the timeframe of 7.27 m3/m, which is close to the volume determination error by the model.

Virtual impedance optimization control strategy for wind turbine grid-forming converters in weak grid

Abstract Grid forming(GFM) technology is key to the effective consumption and grid-friendly integration of large-scale wind power. However, as the new type of power system sees a high penetration of new energy sources and a decrease in circuit capacity, leading to systems exhibiting weak grid characteristics, this paper studies the adaptive characteristics of grid-forming wind turbine converters under weak grid conditions. It investigates the dynamic relationship between power coupling characteristics and the system impedance ratio based on the virtual impedance method and proposes an impedance optimization method to improve the power decoupling accuracy and dynamic response capability of grid-forming converters. The research results show that the grid-forming controller can operate stably under weak grid conditions, an increase in grid impedance ratio leads to stronger power coupling intensity, and the voltage support capability of grid-forming converters weakens. The simulation verifies that the virtual impedance optimization strategy proposed in this paper can effectively improve the power coupling characteristics of the grid-forming converter and enhance the converter’s dynamic response performance under weak grid conditions.

Improvement of Wind Power Prediction by Assimilating Principal Components of Cabin Radar Observations

Abstract Data assimilation is an important approach to improve the prediction performance of near-surface wind and wind power. Based on the four-dimensional variational technique, this study proposes an approach to improve near-surface wind and wind power prediction by extracting and assimilating the principal components of cabin radar radial wind observations installed at wind turbines within a wind farm. The verification for a series of cases under strong and weak vertical wind shear conditions indicates that compared to the simulations without assimilation, the predicted ultra-short-term (0–4 h) mean absolute error of near-surface wind and single turbine wind power could be reduced by 0.09–1.17 m s−1 and 53–209 kW after the assimilation of radial wind directly and by 0.33–1.38 m s−1 and 62–239 kW after the assimilation of principal components. These illustrate that assimilating the principal components of radial wind is superior to assimilating radial wind directly and could obviously reduce prediction error. Further investigation suggests that extracting the principal components of radial wind has marginal influences on the density and distribution of observations, but could obviously reduce the fluctuation of the observations and the correlation among the observations. The prediction improvement by assimilating the principal components of radial wind is essentially due to the assimilation of low-frequency and low-correlation information involved in the observations.

Finite-time hybrid impulsive formation tracking control of multi-agent systems via aperiodic intermittent communication

This article studies the problem of formation tracking control in multi-agent systems, achieved in finite time, under challenging conditions such as strong nonlinearity, aperiodic intermittent communication, and time-delay effects, all within a hybrid impulsive framework. The impulses are categorized as either stabilizing control impulses or disruptive impulses. Furthermore, by integrating Lyapunov-based stability theory, graph theory, and the linear matrix inequality (LMI) method, new stability criteria are established. These criteria ensure finite-time intermittent formation tracking while considering weak Lyapunov inequality conditions, intermittent communication rates, and time-varying gain strengths. Additionally, the approach manages an indefinite number of impulsive moments and adjusts the control domain’s width based on the average impulsive interval and state-dependent control width. Numerical simulations are provided to validate the applicability and effectiveness of the proposed formation tracking control protocols.

Provenance Analysis of the Northern Offshore Mud Area of the Shandong Peninsula, China, Spanning the Last 2000 Years

The mud area in the northern offshore of the Shandong Peninsula constitutes a dynamic source–sink system in China’s continental shelf and is a hotspot for research. However, the provenance of the sediments remains controversial, and the depositional environment is not yet fully understood. This paper performed accelerator mass spectrometry 14C dating, grain-size analysis, clay mineralogic analysis, and geochemical analysis of the ZZ04 sediment core. The results showed that this core primarily comprises silt and clay, reflecting weak sedimentary hydrodynamic conditions and stable deposition. The clay mineral assemblage—illite, smectite, chlorite, and kaolinite—indicates strong physical weathering. The provenance of the mud area was mainly from the Yellow River, Shandong Peninsula rivers, and Yangtze River, highlighting its multi-source characteristics. The smectite/(illite + chlorite) ratio in the ZZ04 core serves as a mineralogical indicator of the East Asian summer monsoon (EASM). Eight significant East Asian winter monsoon (EAWM) intensifications were identified, correlating with global cooling events similar to those at 1.89, 1.4, 1.03, and 0.62 thousand years ago. During the EAWM period, the coastal current and the Yellow Sea warm current play crucial roles in the transportation of matter and heat flux in the mud area. In contrast, during the EASM period, the sediments are predominantly sourced from the Shandong Peninsula rivers, contributing terrigenous materials shaped by chemical weathering.

Design and Investigation of a 10 Gb/s Hybrid Spatial-time Diversity FSO-CDMA Communication System

Abstract This paper presents a novel strategy for free space optical (FSO) communication system that combines hybrid spatial-time diversity and optical code division multiple access (OCDMA). The authors demonstrate a 10 Gb/s hybrid spatial-time diversity FSO-CDMA experimental system for the first time. They investigate the bit error rate (BER) and physical-layer security under weak and strong turbulence conditions. The experimental results demonstrate that the proposed scheme can improve the performance of the FSO-CDMA system. In the hybrid spatial-time diversity FSO-CDMA system, the BER of the eavesdropper (Eve) exceeds the hard-decision forward-error-correction threshold of 3.8E-3. It is also worth noting that Eve can intercept and recover data without a matched decoder in a spatial diversity FSO-CDMA system. As a result, the proposed scheme can simultaneously enhance reliability and physical-layer security compared to time or spatial diversity systems.

A kinesin-like protein, KAC, is required for light-induced and actin-based chloroplast movement in Marchantia polymorpha.

Chloroplasts accumulate on the cell surface under weak light conditions to efficiently capture light but avoid strong light to minimize photodamage. The blue light receptor phototropin regulates the chloroplast movement in various plant species. In Arabidopsis thaliana, phototropin mediates the light-induced chloroplast movement and positioning via specialized actin filaments on the chloroplasts, chloroplast-actin filaments. KINESIN-LIKE PROTEIN FOR ACTIN-BASED CHLOROPLAST MOVEMENT (KAC) and CHLOROPLAST UNUSUAL POSITIONING 1 (CHUP1) are pivotal for chloroplast-actin-based chloroplast movement and positioning in land plants. However, the mechanisms by which KAC and CHUP1 regulate chloroplast movement and positioning remain unclear. In this study, we characterized KAC and CHUP1 orthologs in the liverwort Marchantia polymorpha, MpKAC and MpCHUP1, respectively. Their knockout mutants, Mpkack° and Mpchup1k°, impaired the light-induced chloroplast movement. Although Mpchup1k° showed mild chloroplast aggregation, Mpkack° displayed severe chloroplast aggregation, suggesting the greater contribution of MpKAC to the chloroplast anchorage to the plasma membrane. Analysis of the subcellular localization of the functional MpKAC-Citrine indicated that MpKAC-Citrine formed a punctate structure on the plasma membrane. Structure-function analysis of MpKAC revealed that a deletion of the conserved C-terminal domain abrogates the targeting to the plasma membrane and its function. A deletion of the N-terminal motor domain retained the plasma membrane targeting but abrogates the formation of punctate structure and showed severe defect in the light-induced chloroplast movement. Our findings suggest that the formation of the punctate structure on the plasma membrane of MpKAC is essential for chloroplast movement.

Estimation of random functions proxying for unobservables

This article considers the model Y = M ( X , U ) where U is an unobservable continuously distributed scalar and M is monotonic with respect to U. It is assumed there is an observable scalar W satisfying the restriction T F W | X , U = T F W | U almost surely where T is a known functional and F A|B denotes the distribution of A|B. This article shows that M can be identified under a mild monotonicity condition. This result requires neither statistical independence between X and U nor X to be continuously distributed. The estimation problem is treated when T F A | B ≡ E [ A | B ] . The proposed pointwise estimator of M is asymptotically normally distributed under weak technical conditions. Furthermore, the rate of convergence in probability is equal to n − r / ( 2 r + d + 1 ) where d denotes the dimension of the continuously distributed components of X and r is a positive integer which relates to the smoothness of certain functions. A Monte Carlo experiment is conducted and reveals the benefits of the estimator in the presence of endogeneity. We apply our estimator to estimate the returns to schooling.

Bifurcation structure of steady states for a cooperative model with population flux by attractive transition

AbstractThis paper studies the steady states to a diffusive Lotka–Volterra cooperative model with population flux by attractive transition. The first result gives many bifurcation points on the branch of the positive constant solution under the weak cooperative condition. The second result shows every steady state approaches a solution of the scalar field equation as the coefficients of the flux tend to infinity. Indeed, the numerical simulation using pde2path exhibits the global bifurcation branch of the cooperative model with large population flux is near that of the scalar field equation.

Ritualized host-tourist interaction and storytelling intentions: the roles of sense of belonging and group size

Guided by interaction ritual chains theory, this research assesses the relationship of ritualized host-tourist interactions on sense of belonging and storytelling intentions, using group size (small vs. moderate vs. large) as a moderating variable. Three studies were conducted using different ritual contexts (i.e. tea, bonfire, wedding). Findings suggested that the intensity of host-tourist interactions (strong vs. weak) impacts tourists’ sense of belonging and storytelling intentions. The research also found that sense of belonging mediates, while group size moderates, the relationship of ritualized host-tourist interaction with storytelling intentions. When group size was moderate (small, large), the impact of strong ritualized host-tourist interactions was greater (not significantly different), relative to weak interaction conditions. Theoretical and practical takeaways are provided.

On [formula omitted]-error moment stability and stabilization for discrete-time semi-Markov jump linear systems

In this paper, we study the σ-error moment stability and stabilization for a class of discrete-time semi-Markov jump linear systems (S-MJLS). It is shown that the existing results on σ-error moment stability for discrete-time S-MJLS can be obtained under weaker conditions, and based on the established stability results, the high-order moment stabilization problem is investigated for the first time.

High Performance Rotary Triboelectric Nanogenerator in Weak Wind Conditions through Soft Contact Utilization

High Performance Rotary Triboelectric Nanogenerator in Weak Wind Conditions through Soft Contact Utilization

Subexponential Concentration Inequalities for Bifurcating Markov Chains

In this paper, for bifurcating Markov chains, under weak and general conditions, we establish explicit subexponential concentration inequalities for different types of empirical means of unbounded functions. The subexponential concentration captures the tail behavior of distributions that are less concentrated than the Gaussian distribution. In particular cases, our results recover the existing subgaussian concentration.

Collaborative task decision-making of multi-UUV in dynamic environments based on deep reinforcement learning

ABSTRACT The problem of collaborative task decision-making for unmanned underwater vehicles (UUVs) in an unknown dynamic ocean environment is investigated. In view of the unknown marine environment, a partially observable Markov decision process is designed to achieve partially observable path planning for multi-UUV. Aiming at the problems of long planning time, large amount of data, and insufficient multi-task decision-making capability in the process of multi-UUV underwater collaborative operation, a multi-UUV collaborative task decision-making model based on the multi-agent twin delayed deep deterministic policy gradient (MATD3) algorithm for the dynamic environment is constructed. The implementation of the centralised training with distributed execution (CT-DE) training framework enables each UUV to possess autonomous decision-making capability and ensures task safety under weak communication conditions. The pre-training phase shows that the MATD3 algorithm outperforms the multi-agent deep deterministic policy gradient (MADDPG) algorithm for training multi-UUV autonomous decision-making scenarios in dynamic environments. The simulation experiment results verify that the autonomous decision-making method based on the MATD3 algorithm can effectively solve the multi-UUV collaborative task decision-making problem in unknown dynamic environments, and the task process satisfies the requirements of real-time, safety and economy.