Emergency Operations of Sudden Water Pollution Accidents

Emergency operation technologies can help to make reasonable operation measures of hydraulic structures, which are important to control the scope of the effect arising from an event and reduce the harm caused thereby. The main canal of MRP is divided into three parts in case of sudden water pollution accidents: the accident pool, the upstream section of the accident pool, and the downstream section of the accident pool. For each part, the target and strategy for emergency operation technologies are discussed. With regard to an accident pool, multiple kinds of check gate closing methods, synchronous, asynchronous, identical speed, and different speed are put forward; for the upstream section, a new method of equal-volume operation is introduced; and for the downstream section, three emergency operation methods are proposed. The simulation result of case study shows that the methods raised in this chapter can be used to determine suitable emergency operation measures

Effect of refining slag compositions on its melting property and desulphurization

To investigate the feasibility of the refining slag with low fluoride, some oxides such as Al2O3, SiO2, B2O3, and Li2O were used to replace CaF2 in refining slag with the equivalent weight replacement method, and then the melting temperature and desulphurization capacity of slag were determined. The results show that the melting temperature of slag (CaF2 28 mass%) is less than 1,706 K, when CaF2 is substituted by Al2O3. This slag is able to decrease [S] in steel to less than 0.0060 mass%. In the case of substitution of CaF2 by SiO2, the melting temperature increases, while the desulphurization rate decreases. The fluxing action of B2O3 is stronger than that of CaF2, and the melting temperature decreases to 1,561 K when CaF2 is substituted by B2O3. Li2O can not only lower the melting temperature of slag but also improve the desulphurization rate

Automatic feedback control algorithm for canal for a quick upstream water supply interruption in the case of an emergency

For the sudden upstream water interruption in the canal of an emergency, the existing research method guiding gate control is mainly feed-forward compensation algorithm, under which algorithm the interruption of water diversions is the upstream first and then the downstream. In order to achieve a more flexible water demand for different water diversions purpose, this study used PI water level difference feedback control algorithm to control the gate under this condition. The research results showed that the PI water level difference feedback control algorithm can make the change trend of water level of multi-pool close and reduce the rate of water level decline, and thus prolong the continuous delivery time of pools with offtake delivery demand under sudden upstream water interruption. Moreover, the PI water level difference method has good robustness and can be applied to more complex combinations of inflow and delivery changes. This study provides another way of thinking for the regulation of the gate in the case of sudden upstream water interruption

Automatic feedback control algorithm for canal for a quick upstream water supply interruption in the case of an emergency

For the sudden upstream water interruption in the canal of an emergency, the existing research method guiding gate control is mainly feed-forward compensation algorithm, under which algorithm the interruption of water diversions is the upstream first and then the downstream. In order to achieve a more flexible water demand for different water diversions purpose, this study used PI water level difference feedback control algorithm to control the gate under this condition. The research results showed that the PI water level difference feedback control algorithm can make the change trend of water level of multi-pool close and reduce the rate of water level decline, and thus prolong the continuous delivery time of pools with offtake delivery demand under sudden upstream water interruption. Moreover, the PI water level difference method has good robustness and can be applied to more complex combinations of inflow and delivery changes. This study provides another way of thinking for the regulation of the gate in the case of sudden upstream water interruption

The Relationship between Socioeconomic Status, Mental Health, and Need for Long-Term Services and Supports among the Chinese Elderly in Shandong Province—A Cross-Sectional Study

This study aims to clarify the association between socioeconomic status (SES), mental health, and the need for long-term services and support (NLTSS) of the Chinese elderly, and further, to provide evidence-based suggestions for the development of the long-term services and support (LTSS) system in China. A cross-sectional survey using a multi-stage random sampling method was conducted in Shandong Province, China, in 2017. Data were collected from seniors aged over 60 years old through questionnaires by face-to face interviews. A total of 7070 subjects were included in the final database (40.3% male and 59.7% female). A chi-square test analysis and structural equation modeling (SEM) were employed to explore the relationship between SES, mental health, and NLTSS for both male and female elderly people. The SEM analysis showed that mental health was significantly and negatively associated with NLTSS for both male elderly and female elderly, and it was slightly stronger among the male elderly. A significant and negative relationship was observed between SES and NLTSS for both genders, and the association was stronger among the female elderly. SES exerted a positive effect on mental health for both male and female elderly people, and a slightly stronger effect was found among the male elderly. Advice for the development of a LTSS system in China was given based on the above results

A Model Predictive Water-Level Difference Control Method for Automatic Control of Irrigation Canals

In this paper, automatic control of the water level in an irrigation canal by automatic regulation of intermediate gates was studied. Previous scholars have proposed a water level difference control strategy that works to keep relative deviations in all pools the same for a particular situation where the operator does not have full control over the canal inflow, with the centralized linear quadratic regulator (LQR) control method used. While in practice, the deviation tolerance of pools may differ in some canals which limits the applicability of the control strategy. In this work, a weight coefficient was added to the deviation and the algorithm was improved to keep the relative deviations to certain proportions. The model predictive control (MPC) method was then used with this improved control strategy and was compared to the LQR control method using the same control strategy. The results showed that the improved strategy can keep the water level deviations in all pools to certain proportions, as is our objective. Also, under this difference control strategy, the MPC method greatly improved the control performance compared to the LQR control method

Modeling Long-Distance Forward and Backward Diffusion Processes in Tracer Transport Using the Fractional Laplacian on Bounded Domains

Recent studies have emphasized the importance of the long-distance diffusion model in characterizing tracer transport occurring within both subsurface and surface environments, particularly in heterogeneous systems. Long-distance diffusion, often referred to as nonlocal diffusion, signifies that tracer particles may experience a considerably long distance in either the forward or backward direction along preferential channels during the transport. The classical advection–diffusion (ADE) model has been widely used to describe tracer transport; however, they often fall short in capturing the intricacies of nonlocal diffusion processes. The fractional operator has gained recognition among hydrologists due to its potential to capture distinct mechanisms of transport and storage for tracer particles exhibiting nonlocal dynamics. However, the hypersingularity of the fractional Laplacian operator presents considerable difficulties in its numerical approximation in bounded domains. This study focuses on the development and application of the fractional Laplacian-based model to characterize nonlocal tracer transport behavior, specifically considering both forward and backward diffusion processes on bounded domains. The Riesz fractional Laplacian provides a mathematical framework for describing tracer diffusion processes on a bounded domain, and a novel finite difference method (FDM) is introduced as an effective numerical solver for addressing the fractional Laplacian-based model. Applications reveal that the fractional Laplacian-based model can effectively capture the observed nonlocal tracer transport behavior in a heterogeneous system, and nonlocal tracer transport exhibits dynamic characteristics, influenced by the evolving heterogeneity of the media at various temporal scales

Reconstruction of long-term water temperature indicates significant warming in Polish rivers during 1966–2020

Study region: The study region comprises 125 water gauges from 70 rivers covering the whole territory of Poland. Study focus: The air2stream model was used to reconstruct daily river water temperature (RWT) from 125 water gauges in 70 Polish rivers for the period 1966–2020 (55 years). Then, the annual and seasonal warming trends of RWT, and a biologically relevant metric (the annual number of days when water temperature exceeded 20 °C) were evaluated. New hydrological insights for the region: The modelling results showed that the air2stream model performed well for RWT modeling (the averaged Root Mean Square Error (RMSE) values for the calibration and validation periods are 1.21 and 1.32 °C, and Nash-Sutcliffe efficiency coefficient (NSE) for the two periods are 0.96 and 0.95 respectively). Annual averaged RWT of 121 gauges (96.8 % of the 125 gauges) showed clear warming trend in the past 55 years with the warming rate ranging between 0.08 and 0.44 °C/decade (average: 0.25 °C/decade). The warming trends of river waters on the main rivers and their tributaries are spatially differentiated. Seasonal RWT trends showed that summer is warming fastest, followed by spring and then by autumn and winter. Long-term increases in RWT were typically correlated with increases in air temperatures. For the three large rivers (Vistula, Odra, and Warta), the biologically relevant metric (the annual number of days when water temperature exceeded 20 °C) increased synchronously with the warming of RWT. The results reported in this study will be useful to stakeholders and the reconstructed dataset will be useful to the community for the further study of river thermal dynamics and aquatic habitats in Poland