Decrease In Speed Research Articles

Effects of maximum thickness position on hydrodynamic performance for fish-like swimmers.

When designing the internals of robotic fish, variations in the internal arrangements of power and control systems cause differences in external morphological structures, particularly the positions of maximum thickness. These differences considerably affect swimming performance. This study examines the impact of the topological structure of self-propelled fish-like swimmers on hydrodynamic performance using fluid-structure interaction techniques. Fish-like swimmers with maximum thickness closest to the head exhibit optimal swimming performance, characterized by modest energy consumption for fast-response acceleration during the starting phase and higher swimming velocity for high-speed travel during steady swimming. As the maximum thickness moves toward the middle, acceleration performance significantly weakens and swimming speed decreases, although maximum energy consumption is relatively reduced. This study will provide a notable reference for the morphological design of underwater robotic fish.

Movement Characteristics of Droplet Deposition in Flat Spray Nozzle for Agricultural UAVs

At present, research on aerial spraying operations with UAVs mainly focuses on the deposition outcomes of droplets, with insufficient depth in the exploration of the movement process of droplet deposition. The movement characteristics of droplet deposition as the most fundamental factors affecting the effectiveness of pesticide application by UAVs are of great significance for improving droplet deposition. This study takes flat spray nozzles as the research object, uses the Particle Image Velocimetry (PIV) technique to obtain movement data of water droplet deposition under the influence of rotor flow fields, and investigates the variation characteristics of droplet deposition speed under different influencing factors. The results show that the deposition speed and the distribution area of high-speed (>12 m/s) particles increase with the increase of rotor speed, spraying pressure, and nozzle size. When the rotor speed increases from 0 r/min to 1800 r/min, the average increase in maximum droplet deposition speed for nozzle models LU120-02, LU120-03 and LU120-04 is 33.26%, 19.02%, and 7.62%, respectively. The rotor flow field significantly increases the number of high-speed droplets, making the dispersed droplet velocity distribution more concentrated. When the rotor speed is 0, 1000, 1500, and 1800 r/min, the average decay rates of droplet deposition speed are 36.72%, 20.00%, 15.47%, and 13.21%, respectively, indicating that the rotor flow field helps to reduce the decrease in droplet deposition speed, enabling droplets to deposit on the target area at a higher speed, reducing drift risk and evaporation loss. This study’s results are beneficial for revealing the mechanism of droplet deposition movement in aerial spraying by plant protection UAVs, improving the understanding of droplet movement, and providing data support and guidance for precise spraying operations.

Effects of Single‐Axis and Fixed‐Tilt Photovoltaic Array Construction on the Soil Seed Bank Characteristics in Semi‐Arid Grasslands

ABSTRACTWith the rapid global development of photovoltaic power generation, research on its impact on land and ecosystems has become increasingly significant. However, its impact on soil seed bank characteristics has yet to be better assessed. In this study, monitoring plots were established in a semi‐arid grassland undergoing solar energy development. This setup allowed us, for the first time, to investigate how soil seed bank characteristics respond to the construction of two typical photovoltaic array systems: single‐axis and fixed‐tilt systems. This study demonstrated that in both single‐axis and fixed‐tilt systems, the establishment of photovoltaic arrays resulted in a significant increase in soil seed density, with seed counts rising by approximately 47.5% compared with control sites without arrays. The aggregation effect of soil seed density under the photovoltaic array primarily occurred in the 0–10 cm soil layer. The soil seed density under the single‐axis arrays was higher than that under the fixed‐tilt arrays. The construction of photovoltaic arrays resets local soil and directly changes the micro‐environment—including reductions in solar radiation, decreases in average temperature by 0.1°C, and wind speed decreases by 1.5 m/s—which negatively affected the richness and diversity of the soil seed bank, resulting in a 21.1% decrease in species richness and a 10.1% reduction in seed diversity. Furthermore, this study highlights that seed germination in semi‐arid grasslands is under pressure due to environmental changes associated with photovoltaic construction areas. Specifically, soil moisture and organic matter were the key factors affecting the vegetation restoration potential of the entire construction area. We recommend selecting the single‐axis system of photovoltaic components. This selection is crucial, which considers both energy production efficiency and supports the facilitation of future vegetation ecosystem succession. Altogether, this study provides information for future land‐use planning in photovoltaic construction areas and sustainable development of photovoltaic power generation.

Wind-induced response and control criterion of the double-layer cable support photovoltaic module system

The cable support photovoltaic module system has obvious characteristics of wind-induced vibration. In order to study the wind-induced vibration response characteristics and mechanism of the double-cable support photovoltaic module systems, and further discuss the stiffness control criterion. The wind-induced vibration response of a new type of cable-truss support photovoltaic module system with a span of 35m is studied through the aeroelastic wind tunnel test. Firstly, the scaled aeroelastic test model was established to meet the aeroelastic test requirements. Then, the effects of wind direction, PV module inclination angle, and stability cable initial prestress on the wind-induced vibration response characteristics under uniform flow and turbulent field are studied. Finally, the wind-induced vibration response mechanism and stiffness control criterion are discussed. The results show that the increase of inclination angle will lead to a decrease in critical wind speed, the 0° wind direction is the most unfavorable, and the increase of initial prestress can increase the critical wind speed but is inefficient. The critical wind speed under the turbulent flow field is about 30% higher than that of the uniform flow field. The instability vibration is the result of multi-mode coupled vibration of vertical bending and torsion. It is suggested that the stiffness control criterion is more appropriate as 1/100. The research results are of great significance for the design and application of the cable support photovoltaic module system.

Study on power losses and pressure fluctuations of diffuser mixed flow pump as turbine on different power generation speeds based on energy power models

Variable speed regulation represents an effective means to ensure the efficient operation of the diffuser mixed flow pump as turbine (DMFPAT). This paper employed computational fluid dynamics-based energy power models and high-frequency water pressure fluctuation tests to investigate the power losses and pressure fluctuations of DMFPAT under different power generation speeds. Analysis of power losses reveals that internal power losses in DMFPAT predominantly originate from the turbulent dissipation power (PEPD′) in the entropy production and the turbulent kinetic energy production power (PEBL3) in the energy balance equation, indicating that fully developed turbulence significantly contributes to substantial power losses in DMFPAT. A strong correlation exists between power generation speed and power losses, and decreasing rotational speed results in gradual reduction of power losses in DMFPAT. Additionally, a comprehensive analysis of the pressure fluctuation signals of DMFPAT under variable speed mode was conducted, revealing that the main frequency at each monitoring point is the rotational frequency and its harmonics. As speed decreases, the pressure fluctuation amplitude diminishes. The research presented demonstrates that adjusting the speed not only markedly reduces power losses but also eliminates adverse pressure fluctuations, thereby providing a theoretical basis for the efficient, stable and safe operation of DMFPAT.

Orbital Support and Evolution of CX/OX Structures in Boxy/Peanut Bars

Barred galaxies exhibit boxy/peanut or X-shapes (BP/X) protruding from their disks in edge-on views. Two types of BP/X morphologies exist depending on whether the X-wings meet at the center (CX) or are off-centered (OX). Orbital studies indicate that various orbital types can generate X-shaped structures. Here we provide a classification approach that identifies the specific orbit families responsible for generating OX- and CX-shaped structures. Applying this approach to three different N-body bar models, we show that both OX and CX structures are associated with the x1 orbit family, but OX-supporting orbits possess higher angular momentum (closer to x1 orbits) than orbits in CX structures. Consequently, as the bar slows down, the contribution of higher angular momentum OX-supporting orbits decreases and that of lower angular momentum orbits increases, resulting in an evolution of the morphology from OX to CX. If the bar does not slow down, the shape of the BP/X structure and the fractions of OX/CX-supporting orbits remain substantially unchanged. Bars that do not undergo buckling but that do slow down initially show the OX structure and are dominated by high angular momentum orbits, transitioning to a CX morphology. Bars that buckle exhibit a combination of both OX- and CX-supporting orbits immediately after the buckling but become more CX dominated as their pattern speed decreases. This study demonstrates that the evolution of BP/X morphology and orbit populations strongly depends on the evolution of the bar angular momentum.

Effect of obstruction ratio rate of change gradients on the deflagration characteristics of H2-Air premixed gases

To investigate the effect of the gradient of obstruction ratio change rate on the H2-Air premixed gas combustion explosion in the semi-confined space, Fluent software is used to simulate the explosion flame, turbulent turning and pressure wave coupling process under the conditions of obstacles with different obstruction ratios change rate. The results indicate that as the obstruction ratio's rate of change increases, flame propagation speed decreases, while pressure peak and pressure change rate increase. The flame front becomes sharper, and a positive change in obstruction ratio more significantly affects flame shape and speed than a negative change. At obstruction ratio change rates of −0.3 and −0.2, the flame front area and peak area reach their maximum values. At a change rate of 0.3, the pressure peak is 232 kPa, and the maximum pressure change is 126 kPa/ms, indicating the explosion intensity reaches its peak.

Cognitive functions explain discrete parameters of normal walking and dual-task walking, but not postural sway in quiet stance among physically active older people.

Postural control is dependent on the central nervous system's accurate interpretation of sensory information to formulate and execute adequate motor actions. Research has shown that cognitive functions are associated with both postural control and fall risk, but specific associations are not established. The aim of this study was to explore how specific components of everyday postural control tasks are associated with both general and specific cognitive functions. Forty-six community-dwelling older adults reported their age, sex, physical activity level, falls and fall-related concerns. The following cognitive aspects were assessed: global cognition, executive functions, processing speed and intraindividual variability. Postural control was quantified by measuring postural sway in quiet stance, walking at a self-selected pace, and walking while performing a concurrent arithmetical task. Separate orthogonal projections of latent structures models were generated for each postural control outcome using descriptive and cognitive variables as explanatory variables. Longer step length and faster gait speed were related to faster processing speed and less intraindividual variability in the choice reaction test. Moreover, longer step length was also related to less fall-related concerns and less severe fall-related injuries, while faster gait speed was also related to female sex and poorer global cognition. Lower dual-task cost for gait speed was explained by the executive function inhibition and faster processing speed. Postural sway in quiet stance was not explained by cognitive functions. Cognitive functions explained gait speed and step length during normal walking, as well as the decrease of gait speed while performing a concurrent cognitive task. The results suggest that different cognitive processes are important for different postural control aspects. Postural sway in quiet stance, step time and gait variability seem to depend more on physical and automatic processes rather than higher cognitive functions among physically active older people. The relationships between cognitive functions and postural control likely vary depending on the specific tasks and the characteristics of different populations.

Behavioral Responses of Chironomus aprilinus Larvae as Proxies for Cyanobacterial Metabolite Interactions: Insights from Ternary Combinations.

This study aimed to assess the behavioral responses (immobilization, horizontal and vertical motility, and response to light) of Chironomus aprilinus larvae exposed to individual cyanobacterial metabolites aeruginosin 98B (AER-B), anabaenopeptin-B (ANA-B), and cylindrospermopsin (CYL), and their binary and ternary mixtures. The investigation revealed that single metabolites ANA-B and CYL exhibited the highest potency in immobilizing the larvae. Notably, the binary mixture AER-B+CYL induced a remarkably strong synergistic interaction, while other tested binary and ternary mixtures demonstrated antagonistic effects. Both individual metabolites and their mixtures led to a decrease in larval movement speed, with the AER-B+CYL combination showing a very synergistic effect, and strong antagonistic interactions between the oligopeptides in the ternary mixture. Conversely, while AER-B and the binary mixture ANA-B+CYL stimulated vertical movement, other single metabolites and binary and ternary mixtures decreased this parameter. Antagonistic interactions were observed in all mixtures. ANA-B emerged as the most potent inhibitor, yet all tested metabolites and their mixtures decreased larval response to light, displaying synergistic interactions, except for the AER-B+ANA-B mixture at 250 μg L-1 + 250 μg L-1. These findings underscore the sensitivity of Chironomus larvae behavioral parameters as indicators of environmental stressors and mixtures. Consequently, they are recommended for assessing toxic effects induced by cyanobacterial products and other bioactive chemicals.

Application of synchronous music reinforcement to increase walking speed: A novel approach for training intensity.

Walking is a common and preferred form of exercise. Although there are current recommendations for walking volume (e.g., steps per day), recent research has begun to distinguish volume from intensity (e.g., "brisk" walking) as an important dimension of exercise. Increasing intensity may confer health advantages beyond volume measures because it shifts cardiovascular performance to more vigorous training zones. Reinforcement-based approaches have been valuable in increasing volume measures of exercise, and the present study sought to develop a corresponding reinforcement approach to training walking intensity. For this study, we used a continuous reinforcement paradigm where music played only while walking met specified criteria; otherwise, music playback stopped. As a result, music was synchronized with walking performance. Seventeen participants walked on a nonmotorized treadmill at a self-selected pace. Across the session, different conditions arranged for music to play independent of walking speed or contingent on speed increases or decreases. An extinction component assessed performance when music was withdrawn completely. Walking speed was selectively increased and decreased by adjusting the contingencies that were arranged for music, and variability in speed increased during extinction, with both findings indicating that music was a reinforcer. Heart rate was also increased to moderate-vigorous intensities during reinforcement. The findings provide a compelling case that walking intensity can be modified by music reinforcement. We suggest that synchronous schedules may be an important foundation for future exercise technologies that are based on reinforcement.

Cognition in (pre)symptomatic Dutch-type hereditary and sporadic cerebral amyloid angiopathy.

Cerebral amyloid angiopathy (CAA) is a main cause of cognitive dysfunction in the elderly. We investigated specific cognitive profiles, cognitive function in the stage before intracerebral hemorrhage (ICH), and the association between magnetic resonance imaging (MRI) based cerebral small vessel disease (cSVD) burden in CAA because data on these topics are limited. We included Dutch-type hereditary CAA (D-CAA) mutation carriers with and without ICH, patients with sporadic CAA (sCAA), and age-matched controls. Cognition was measured with a standardized test battery. Linear regression was performed to assess the association between MRI-cSVD burden and cognition. D-CAA ICH- mutation carriers exhibited poorer global cognition and executive function compared to age-matched controls. Patients with sCAA performed worse across all cognitive domains compared to D-CAA ICH+ mutation carriers and age-matched controls. MRI-cSVD burden is associated with decreased processing speed. CAA is associated with dysfunction in multiple cognitive domains, even before ICH, with increased MRI-cSVD burden being associated with slower processing speed. Cognitive dysfunction is present in early disease stages of cerebral amyloid angiopathy (CAA) before the occurrence of symptomatic intracerebral hemorrhage (sICH). Presymptomatic Dutch-type CAA (D-CAA) mutation carriers show worse cognition than age-matched controls. More early awareness of cognitive dysfunction in CAA before first sICH is needed. Increased cerebral small vessel disease CAA-burden on magnetic resonance imaging is linked to a decrease in processing speed.

Influence of energy-saving devices on the hydrodynamic characteristics of a waterjet-propelled ship: Experimental and numerical investigation

Installing stern energy-saving devices can help conserve energy and enhance ship speed, particularly for medium-to-high-speed ships. This study focuses on a waterjet-propelled ship and examines the performance of two energy-saving devices: the interceptor and stern flap. The investigation involves conducting a comparative analysis through towing-tank experiments and utilising Reynolds-averaged Navier–Stokes (RANS) numerical methods. The findings suggest that incorporating energy-saving devices alters the capture flow of the waterjet-propelled ship. Furthermore, these devices reduce ship resistance, resulting in a maximum decrease in the impeller speed of the self-propulsion point up to 5%. Following the installation of energy-saving devices, the propulsion efficiency of the waterjet-propelled ship demonstrates an enhancement ranging from 0.5% to 5.7%. This increase in propulsion efficiency emerges as a principal factor contributing to the energy savings facilitated by the stern energy-saving device. Upon comparison, it was found that within the Fr range of 0.3–0.5, the stern flap exhibited a superior energy-saving effect. Conversely, when Fr exceeded 0.5, the interceptor demonstrated a more pronounced energy-saving effect. Finally, the mechanisms of the stern energy-saving devices are elucidated based on the momentum velocity coefficient, thrust deduction fraction, and changes in the internal and external flow fields of the waterjet-propelled ship.

Use of Gait Profile Score and Gait Variable Score to quantify patient improvement immediately following neuro-orthopedic surgery in patients with cerebral palsy – A prospective cohort study

BackgroundThe Gait Profile Score (GPS) and the Gait Variable Score (GVS) are summary measures used to assess the long-term effects of neuro-orthopedic surgery (NOS) in children with cerebral palsy (cwCP). Research questionWhat are the immediate changes after NOS as assessed by GPS and GVS, and how does GPS variation (ΔGPS) compare to the clinical opinion of the NOS outcome? MethodsProspective single-arm cohort study. CwCP were assessed before NOS and after the first month of weight-bearing. Popliteal angle, ankle passive dorsiflexion (pDF), and spasticity were collected at the bedside. During walking, pain was assessed using NPRS, and speed was obtained from gait analysis data, as well as GPS and GVS. Longitudinal variations were analyzed using the Wilcoxon test. Children were classified as Improved (I), Stable (S), or Worsened (W) according to ΔGPS and the cut-off threshold recommended in literature. Two clinicians independently classified patients either as I, S, or W based on surgical outcome. Agreement between these two classifications was analyzed using Cohen’s k. ResultsTwenty cwCP, 11.4 (3.4) years, were included. At the follow-up: the popliteal angle was reduced by 20° (p=0.015); pDF increased by 10° (p<0.001), and triceps surae spasticity decreased (p=0.008). Pain decreased in four children. GPS decreased from 12.7 (range 8.1–27.7) to 11.8 (7.6–17.6) (ES=0.514, p=0.046), despite a decrease in gait speed (p<0.001). GVS better highlighted the effect of NOS after single-level surgery. Clinically, 18/1/1 children were classified I/S/W. Based on ΔGPS, 9/8/3 children were classified I/S/W. Such disagreement (k=0.119, p=0.227) was mainly due to the different focus of the two assessments. SignificanceFollowing NOS, immediate improvements in walking kinematics were observed.

Gait speed in older adults: exploring the impact of functional, physical and social factors

Purpose: With age there is a neuromuscular and cognitive decline that impacts on functional ability. One of the most characteristic and easily recognisable signs of this decline is a decrease in usual gait speed. For older adults, gait speed is a non-invasive indicator of health and functional status and is regarded as a vital sign. As it predicts various conditions later in life, measuring usual walking speed is crucial in the clinical setting. Therefore, analysing and determining the association between walking speed and the impact of functional and socio-economic variables may facilitate the prevention of associated health problems and the maintenance of physical function in older adults. This study aims to identify the key factors that influence walking speed in older adults, as well as to examine the influence of socio-economic status on walking speed. Methods: A total of 1253 older adults (89.5% women) with a mean age of 78.1 ± 5.8 voluntarily participated in this descriptive cross-sectional study, which examines the results of functional capacity tests and socioeconomic data in older adults. To assess physical function, SPPB tests (chair stand test, balance tests, gait speed test), manual grip strength, muscle quality index, and power were conducted, in addition to measuring body composition and socioeconomic status. Results: The final regression model showed that gait speed was significantly partially explained (R2=0.35; p&lt;0.01) by the socioeconomic environment, age, balance, and relative power. At the same time, belonging to a higher socio-economic environment is linked to lower relative power (p&lt;0.01; η2=0.07). Conclusions: Exploring the factors that affect walking speed in older adults, this study highlights that age, relative power and balance are significant determinants. These clinical markers provide crucial information for designing personalized and effective interventions to promote healthy aging. Keywords: Frailty, gait speed, elderly, relative power, socioeconomic status.

Vertical variations in planar lamination of marine shale: Elucidating hydrodynamic changes during the Ordovician–Silurian transition on the Upper Yangtze Block

The hydrodynamics and their evolution on the Upper Yangtze Block during the Ordovician–Silurian transition period remain unclear. The present study is an assessment of how regional and global events may have influenced the hydrodynamic evolution based on a planar lamination investigation of the shales from the Upper Yangtze Block. Analyses of large thin sections and argon-ion polished thin sections using field emission-scanning electron microscopy (FE-SEM) showed that there are four types of planar lamination, namely, silty graded planar lamination (SGPL), silt–clay graded planar lamination (SCGPL), silt–clay interlaminated planar lamination (SCIPL), and paper-like planar lamination (PPL). SGPL is formed by turbidity current with a flow speed less than 15 cm/s. SCGPL is formed by turbidity currents with a flow speed less than 15 cm/s for normal grading type and 15–25 cm/s for alternating grading type. SCIPL has a continuum of sparsely spaced type, closely spaced type, and alternating type, which is formed by bottom current with an increasing flow speed from 15 to 25 cm/s to above 25 cm/s. PPL can be divided into normal grading and composite grading types. The former is formed by vertical settling, while the latter is formed by bottom current with a flow speed of 5–15 cm/s. Vertically, types of planar lamination varied from SGPL to PPL and then SCIPL manifesting the waxing and waning of flow speed with a positive excursion at graptolite biozone Metabolograptus extraordinarius (WF4) and a negative excursion at graptolite biozone Persculptograptuspersculptus (LM1). The sudden decrease in flow speed across Linxiang and graptolite biozone Paraorthograptuspacificus (WF3) and the subsequent progressive increase from graptolite biozone Akidograptus ascensus (LM2) to graptolite biozone Demirastrites triangulatus (LM6) and to graptolite biozone Stimulograptus sedgwickii (LM8) during deposition of the Ordovician–Silurian transition succession on the Upper Yangtze Block were linked to the bulge uplift, the rapid subsidence, and the relaxation controlled by the Kwangsian orogeny. In contrast, the positive excursion at WF4 and the negative excursion at LM1 were strongly controlled by the Hirnantian Glaciation and global warming, respectively.

The motion of a self-propelling two-sphere swimmer in a weakly viscoelastic fluid

We study analytically the propulsion of a force- and torque-free swimmer composed of two counterrotating spheres of differing radii through a viscoelastic fluid described by the Giesekus constitutive model. Our analysis includes both swimmers composed of directly touching spheres and those composed of spheres separated by some finite distance. The propulsion speed of the swimmer is calculated by first expanding the equations of motion and the Giesekus constitutive model as a power series in the Weissenberg number, and then using the Lorentz reciprocal theorem to determine the first-order propulsion speed using the known flow fields for rotating and translating two-sphere geometries at zeroth order. We calculate the relative rotation speeds of the two spheres necessary to maintain the torque-free condition, including an approximate correction for fluid elasticity. The impact of the separation distance between the two spheres, the ratio of their radii, and the value of the Giesekus mobility parameter α on the propulsion speed are all examined; we find that the propulsion speed of the swimmer is maximized for two touching spheres with a radius ratio of approximately 0.7, with a Giesekus mobility parameter of α=0, corresponding to an Oldroyd-B fluid. We also quantify how the increased shear-thinning in the fluid, represented by increasing values of α, results in a significant decrease in the swimmer speed. Finally, through calculations of the fluid stresses around the two-sphere swimmer, we demonstrate the development of enhanced hoop stresses around the smaller sphere, which drive the expulsion of stretched fluid behind the smaller sphere and induce motion of the swimmer in the direction of the larger sphere.

Impacts of Large-Scale Offshore Wind Farms on Tropical Cyclones: A Case Study of Typhoon Hato

Abstract With the rising global demand for renewable energy sources, a great number of offshore wind farms are being built worldwide, as well as in the northern South China Sea. There is, however, limited research on the impact of offshore wind farms on the atmospheric and marine environment, particularly tropical cyclones, which frequently occur in summertime in the South China Sea. In this paper, we employ the Weather Research and Forecasting (WRF) Model to investigate the impacts of large-scale offshore wind farms on tropical cyclones, using the case of Typhoon Hato, which caused severe damage in 2017. Model results reveal that maximum wind speeds in coastal areas decrease by 3–5 m s−1 and can reach a maximum of 8 m s−1. Furthermore, the wind farms change low-level moisture convergence, causing a shift in the precipitation center toward the wind farm area and causing a significant overall reduction (up to 16%) in precipitation. Model sensitivity experiments on the area and layout of the wind farm have been carried out. The results show that larger wind farm areas and denser turbine layouts cause a more substantial decrease in the wind speed over the coast and accumulated precipitation reduction, further corroborating our findings. Significance Statement This study holds significant implications for developing offshore wind farms in tropical cyclone-prone regions like the South China Sea. By focusing on Typhoon Hato as a case study, the research sheds light on the previously understudied relationship between large-scale offshore wind farms and tropical cyclones. The observed decrease in coastal wind speeds and altered precipitation patterns due to wind farm presence highlights the potential for mitigating cyclone-related risks in these regions. Additionally, the study’s sensitivity experiments underscore the importance of careful planning and design in optimizing wind farm layouts for maximum impact reduction. This research contributes vital insights into sustainable energy infrastructure development while minimizing environmental and meteorological risks in cyclone-prone areas.

Flood simulation and impact analysis of Xun River under backwater condition

Abstract The intersection of river channels is easy to cause the backside of the main flow, which greatly influences the change of hydrological conditions of river channels. To study the changing characteristics of river flood under the condition of uplift, a one-dimensional hydrodynamic model was established to simulate the evolution process of river flood under the condition of seeking river uplift. Factors such as distance, height, flood speed, inundation area, inundation depth, and flood speed were selected to analyze the changing rules of the influence of river bullying. The results show that the influence degree of the river following is closely related to the size of the flood. Under the same earthquake magnitude, the backwater distance, backwater height, inundation area, inundation depth, and inundation speed of sub-river flood increase with the increase of flood magnitude, while the flood speed decreases. When the magnitude of the flood is once in 200 years, the flood elements reach the maximum, the reflux distance is 8, 368 m, the reflux height is 3.2 m, and the velocity is reduced by 43.2%. This study can provide relevant data for the flood control work in the Sun River basin and provide a reference for the scheme design of tributary interchanges.

ВЛИЯНИЕ СОВРЕМЕННОГО ИЗМЕНЕНИЯ КЛИМАТА НА ИСПАРЕНИЕ С ВОДНОЙ ПОВЕРХНОСТИ В ИЛЕ-БАЛКАШСКОМ БАССЕЙНЕ

Using the Ile-Balkash basin as an example, changes in evaporation from the water surface over the last 40 years, as well as changes in the main meteorological elements that affect evaporation, are considered. Within the framework of this work, the changes in evaporation from the water surface for 1996-2020 in relation to the previous period of 1980-1995 were assessed. It was established that over the last 20 years, there was a slight increase in evaporation at many lowland stations of the Ile-Balkash basin and it is about 1-10 %. In mountainous areas and near large water areas, such as Balkash and Ulken Almaty Lakes, there is a decrease in evaporation by about 2-9 %. The main factors influencing the change in evaporation values from the water surface were analyzed. It was concluded that the increase in evaporation from the water surface at the lowland stations in the Ile-Balkash basin is mainly due to the increase in air temperature and some increase in precipitation, and the decrease in evaporation in mountainous areas and near a water area is caused by the decrease of average wind speed and an insignificant increase in air humidity. This study can help support decision making in the agriculture and water resources sector, since evaporation from the water surface is involved in many hydrological, climatic and hydrodynamic models. Therefore, the obtained results can be used in many scientific calculations.

Multi-objective optimization and off-design performance analysis on the ammonia-water cooling-power/heating-power integrated system

The utilization of ammonia-water as a working fluid in energy conversion systems presents a promising approach for efficient geothermal energy development. In this paper, a novel ammonia-water cooling-power/heating-power integrated system is presented, a structure design method suitable for the integrated thermal system is developed, and a comprehensive analysis of system performance using thermodynamic, economic, and off-design analytical methods is conducted. This study explores the impact of various variables on system design and off-design performance. The results demonstrate that optimal design performance is achieved at evaporation temperatures of 3.5 °C (cooling-power) and 20 °C (heating-power), and the hot-part temperature difference is 21 °C. Lower mass flow rate and ambient temperature lead to improved off-design performance. Due to the influence of pressure on the phase transition temperature of geothermal water, the position of the phase transition zone has shifted, resulting in a change in the mass flow rate of ammonia-water. When the pressure ratio drops below 0.9, the heat release during the phase transition of geothermal water is incomplete, leading to a significant decrease in pump speeds by 44.76 % and 41.14 % in the two modes respectively. This work provides valuable insights and references for the design and optimization of integrated thermal systems.