Natural Flow Research Articles

An updated review on the diagnosis and treatment of nocturia in Parkinson’s disease

Background and objectives. In recent years, neurologists have increasingly focused on the non-motor symptoms of Parkinson's disease, given their significant impact on patients' quality of life. Among these symptoms, nocturia is a common autonomic disturbance. With new insights emerging on its diagnosis and treatment, an updated review of nocturia in Parkinson's disease is essential. Materials and methods. This narrative review is the result of a thorough search in the most important electronic databases (PubMed, Google Scholar, Embase, and Science Direct) for articles published in the English language starting from 1 January 2015 involving human subjects on the topic of nocturia in Parkinson’s disease, focusing on the diagnosis and therapeutic approaches. Results. This section can be divided into three parts, showing the natural flow of understanding, diagnosing, and managing nocturia in Parkinson’s disease. While initially, the most relevant pathophysiological mechanisms are reviewed in detail, the authors offer a diagnosis workflow to facilitate the detection of nocturia among Parkinson’s disease patients. Finally, several strategies for resolving nocturia and other lower urinary tract symptoms are highlighted. Conclusions. Nocturia remains a crucial non-motor symptom in Parkinson’s disease, having a significant negative impact on the patient’s quality of life. Based on current knowledge, the diagnosis of nocturia should be easier and faster, ensuring the use of appropriate treatment options.

A Low-Impact Development-Based Modeling Framework for Flood Mitigation in a Coastal Community

Urbanization is known to increase the volume of stormwater runoff and peak flow rates, which leads to changes in the natural flow regime and increases the likelihood of flooding. Low-impact development (LID) practices seek to reduce runoff volume and peak flow and are generally considered to be a more sustainable solution for urban stormwater management. In this study, we present a systematic approach to address nuisance flooding issues in small cities and communities. As an application, the effectiveness of two LID practices, rain barrels and permeable pavements, were explored in mitigating the urban flooding problem of a highly urbanized small coastal watershed in Alabama, USA. The EPA Stormwater Management Model (SWMM) was first calibrated for water depth using data collected at multiple sites within the watershed during the 2014–2015 period. The calibrated model was then used to first identify the areas prone to flooding using design storms with 1, 2, 5-, 10-, 50-, and 100-year return periods. Floodplain maps were generated for those design storms with HEC-RAS. Next, LID options upstream of those flood-prone areas were assessed to potentially minimize the flooding risks. The results indicate that LID controls can have considerable benefits for stormwater management by reducing runoff volume (1–24%), peak flow rates (18–25%), and water depth (5–15%), potentially returning watersheds to their natural flow regimes, thereby minimizing the flooding risk in urbanized areas. However, the effectiveness of LIDs, especially for the runoff volume, quickly diminishes as the return periods of the storms increase. Rain barrels were identified as the most economical and effective LID within the drainage system.

Assessing hydrological changes in the Ganga River with the range of variability approach

ABSTRACT The study quantitatively assesses the hydrological alterations induced by the Luv Kush Barrage on the Ganga River, India, using the Range of Variability Approach (RVA) to analyze changes in flow conditions before and after the barrage construction. The Ganga River, a crucial water source for millions, has experienced significant hydrological changes due to human interventions, notably the construction of the Luv Kush Barrage. Employing indicators of hydrological alteration (IHAs), we compared pre-impact (1972–1994) and post-impact (2001–2014) flow data to ascertain the barrage’s effects on the river’s flow regime. Our findings reveal significant alterations in the magnitude of monthly streamflow, especially during the monsoon season, with notable decreases in July, August, and September. Alterations were observed in the annual extreme flow conditions, frequency, and duration of high and low pulses, indicating a comprehensive impact on the river’s natural flow patterns. These alterations affect the river’s ecological health, affecting aquatic habitats, fishery resources, and community livelihoods dependent on the river. The study underscores the necessity for integrated water resource management practices that consider the ecological and socio-economic implications of hydrological alterations.

Performance Characteristics of a Free-Breathing Polymer Electrolyte Fuel Cell with Various Channel Shapes

This study utilized a small free-breathing fuel cell, with an active area of 4 cm2 (2 cm x 2cm), and channel cathodes with various channel shapes, to experimentally investigate the effect of channel structure on cell performance, to numerically analyze the natural convection air flow in channels, and to compare with the results of performance characterisitics. The results indicated that, compared with a conventional cathode separator with four straight channels (with a width of 3 mm, a depth of 3 mm, and a rib width of 2 mm), cell performance was improved by eliminating some of the channel ribs and increasing the opening ratio, up to a point. A separator with 2 mm square ribs rotated by 45° further improved cell performance. However, when the opening ratio exceeded 72% with a straight center rib of 2 mm width, cell performance leveled off. The analysis results revealed that separators with modified channels promoted natural convection.

Schlieren Image Velocimetry and Modal Decomposition Study of Preheated Isothermal Flow From a Generic Multi-Swirl Burner

Abstract This study presents an experimental investigation into the turbulent flow characteristics of an unconfined counter-rotating dual swirl burner under external acoustic excitation. Utilizing Schlieren image velocimetry (SIV), we capture the velocity field of the swirling jets. Mean velocity field analysis reveals the upstream propagation of the central recirculation zone within the burner passages. Through proper orthogonal decomposition (POD) analysis on instantaneous axial velocity fields, coherent structures are identified and the impact of different actuation methods on spatial modes is illustrated. Spatial modes of the unforced (natural) flow show the presence of a single and double helical precessing vortex core (PVC) modes at St = 0.53. Low-frequency acoustic actuation (St = 0.46) effectively suppresses the PVC mode, while high-frequency (St = 2) actuation stabilizes it. Broadband excitation of the flow field, however, induces the excitation of both single and double helical PVC modes.

The effect of ship-induced wave trains on periphytic algal communities in the littoral zone of a large regulated river (River Danube, Austria)

Riverine ecosystems are profoundly influenced by hydrological dynamics and natural flow regimes, which dictate the temporal variability of water levels and the amplitude of fluctuations. Human activities, particularly navigation and hydropower generation, have significantly altered these natural patterns, leading to detrimental impacts on the physical, chemical, and biological integrity of river ecosystems. The littoral zone, in particular, is highly susceptible to anthropogenic disturbances, experiencing disruptions in biological activity and biogeochemical processes. This study evaluates the effects of ship-induced wave trains on the structural and functional properties of periphytic algal communities in a regulated river environment. Using data from the Austrian Danube River, periphytic algae's immediate and long-term responses to wave events generated by different types of ships were investigated. Immediate reactions of periphytic algae to wave trains were characterized by reductions in the effective quantum yield of PS II, indicating stress-induced down-regulation of photosystem II photochemistry. Abrasion and remobilization of periphytic algae due to wave action led to increased resuspension of chlorophyll-a into the water column. Furthermore, ship-induced wave trains influenced the pigment composition of periphyton, with photoprotective mechanisms being activated in response to fluctuating light conditions. Long-term effects of wave impact on periphytic algae biomass varied depending on water depth and exposure to aerial stress. While wave action mitigated desiccation stress in shallow areas, it resulted in biomass reduction and alterations in community composition in deeper zones. Notably, the occurrence of diatoms decreased in wave-impacted areas, potentially shifting the community towards Chlorophyceae dominance. Overall, this study underscores the complexity of ship-induced wave impacts on riverine ecosystems and highlights the importance of considering both immediate and long-term responses of periphytic algal communities. Understanding these dynamics is crucial for informing sustainable management strategies aimed at mitigating the adverse effects of navigation activities on riverine biodiversity and ecosystem functioning.

Research on Production Operation System of Sucker Rod Pumping Units

Oil is the most important raw material in modern industry, and its extraction mainly relies on natural flow and artificial lifting. Sucker rod pumping is currently the most widely used method of artificial lifting for mechanical oil extraction, accounting for about 60% to 70% of all methods. This paper deeply explores the theoretical methods involved in the production operation process of sucker rod pumping units. From the perspective of sucker rod pumping unit production operation, a literature review is conducted on the flow patterns in the wellbore, pump efficiency analysis, and intermittent oil extraction systems, clarifying the optimization objectives of liquid production and system efficiency, and sorting out from the aspects of dynamic liquid level, pump efficiency, reasonable submergence depth, and intermittent operation systems. Through in-depth analysis of these key areas, a solid methodological foundation is provided for the future design and development of sucker rod pumping unit production operation systems.

Photodegradation potential of selected non-steroidal anti-inflammatory drugs in a middle-order Alpine river downstream of a wastewater treatment plant, during a year of enduring water scarcity

The year 2022 was characterised by significant water shortages and droughts in Italy, with the most pronounced impact observed in the North-Western regions, including Piemonte. In conditions of water scarcity, treated wastewater undergoes little dilution by natural flows and this can deeply affect the chemistry of water-poor rivers and streams. However, increased pollution by wastewater would be partially offset by fast photodegradation of pollutants in shallow water and by the longer time allowed to photochemical reactions if water flows more slowly. We assessed the latter phenomena in the Stura di Lanzo, a middle-order Alpine river tributary of the largest Italian river, the Po, and affected by a wastewater treatment plant (WWTP). In 2022, the concentration values of the photochemically significant parameters nitrate, nitrite, and DOC were usually higher downstream of the WWTP outlet, which could slightly favour indirect photodegradation reactions. Direct and indirect photodegradation was assessed for the non-steroidal anti-inflammatory drugs paracetamol, diclofenac, and naproxen, all undergoing rather fast photoreactions. Photochemistry model results show that the three compounds would undergo 10–40 % photodegradation in spring and summer along the stretch separating the wastewater outlet from the confluence of Stura into the Po. Photodegradation would continue in the latter, but other WWTPs might contribute additional pollution in the meanwhile. Albeit significant, photodegradation could only partially promote the elimination of the contaminants.

Numerical prediction of passive speed and performance for multistage pump without power drive in natural flow process

With the development of engineering applications and the increase in system complexity, some particular fields, such as liquid rocket engine turbopumps, aircraft engine fuel systems, and marine natural flow cooling systems, are increasingly focusing on the performance characteristics of pumps under natural flow conditions. The pump is in the form of resistance components under natural flow conditions without a power drive. The impeller undergoes passive rotation by the impact of inlet flow. Due to the specificity of its operating conditions and performance indicators, the pump's natural flow performance cannot be evaluated by regular methods. Therefore, this paper proposed a numerical prediction method for pump natural flow performance based on a coupled computational fluid dynamics coupled with six-degrees-of freedom model. The performance of a multistage pump with guide vanes was evaluated under different natural flow conditions, and the accuracy was verified by experimental measurements. The transient variation mode of pump performance parameters with time at the initial stage of natural flow impact was analyzed. The flow field's transient evolution characteristics and the wall shear stress variation during natural flow were investigated. It was found that the impeller's passive rotational speed increases linearly with the natural flow rate, while the hydraulic loss shows an exponentially increasing trend. Meanwhile, the natural flow loss coefficient shows an exponentially decreasing trend and gradually tends to a stable value. The high turbulent kinetic energy inside the impeller is mainly distributed in the flow separation region and large velocity gradients. The distribution of shear stresses is closely related to the flow behavior inside the pump and the geometrical features of the hydraulic components.

Establishing a Remote Area Network for an Automation System: A Case Study of Yeni Karpuzlu Drinking Water Automation

Yeni Karpuzlu is a town located in the Ipsala district of Edirne province. The drinking water needs of this town are supplied from a deep water well. Water is pumped from the deep well using a submersible pump and sent to a 500-m 3 capacity concrete water tank. Here, the water goes the town's water demand through natural flow. The water is then sent from the tank, which is located 30 meters above ground level, to the town. There is a distance of 800 meters between the well and the tank, and 6000 meters between the tank and the control center located in the town. A local network has been established using outdoor access points for communication between the industrial control devices located at these three points. Data from the instruments are collected at a speed of 300mbps. Additionally, it is sent to the video center via IP cameras for area security. All devices on this network communicate with each other and are controlled. This paper will discuss the operation of the automation system mentioned above. Operations include the pump operation based on tank levels, pressure control using an adjustable valve to maintain network pressure, and monitoring and control operations from the central unit.

Sediment Storage and Fluvial Sediment Transport Linkages Across an Experimental Flood Sequence

AbstractRiver channels are maintained by coordination between flow hydraulics, sediment supply, riparian vegetation, and sediment transport. This coordination is challenging to understand in natural flow regimes, where climatic and environmental drivers produce episodic flood and sediment supply events. To better understand the response of channels to flood sequences, we have undertaken laboratory flume experiments on sediment storage and export across a sequence of alternating hydrographs. Our experiments indicate that accumulated sediment storage before floods predicts sediment transport during floods, with sediment storage depletion during floods causing a nonlinear variation of sediment‐transport rates through time. Likewise, sediment storage between floods follows a growth‐to‐saturation pattern, whereby the sediment transport gradually increases toward the sediment feed rate depending on the occupation of available sediment storage zones. To describe these non‐linear variations, we developed a mathematical model which represents sediment transport and storage as a coupled dynamical system. This work highlights the crucial role that within‐channel sediment storage and its history play in determining sediment export in rivers.

Natural Flow Simulation in a Baisin considering Artificial Water Cycle

This study seeks to regionalize the parameters of the grid-based rainfall-runoff model (GRM) and simulate the natural flow considering an artificial water cycle. We established a water supply and demand network for the Han River basin, derived data related to the artificial water cycle through various organizations, and performed a water budget analysis by reflecting the simulated natural flow. When comparing the results of regionalization using only the Chungju Dam parameters and those using the Chungju Dam and Soyanggang Dam parameters, both results for the simulated flow showed good agreement with the observed flow, and the fitness evaluation results were also high (pentad: NSE 0.913–0.977, KGE 0.795–0.935, CC 0.974–0.995). The natural flow simulated by the GRM and TANK indicated that both models were able to reproduce the observed data well. Water budget analyses were performed for different time intervals, and daily analysis exhibited relatively lower fitness than pentad analysis (daily NSE 0.887-0.963, KGE 0.792-0.928, CC 0.960-0.990), but no significant difference was observed. The results indicated that the simulation of natural flow through the GRM was appropriate, and the model was sufficiently applicable to a disturbed watershed.

Index-Based Alteration of Long-Term River Flow Regimes Influenced by Land Use Change and Dam Regulation

The growing population and expansion of rural activities, along with changing climatic patterns and the need for water during drought periods, have led to a rise in the water demand worldwide. As a result, the construction of water storage structures such as dams has increased in recent years to meet the water needs. However, dam construction can bring significant alterations to the natural flow regime of rivers, and it is therefore essential to understand the potential effects of human structures on the hydrological regime of rivers to reduce their destructive impacts. This study analyzes the hydrological changes in the Shahrchai River in response to the Shahrchai Dam construction in Urmia, Iran. The study period was from 1950 to 2017 at the Urmia Band station. The Indicators of Hydrological Alteration (IHA) were used to analyze the hydrological changes before and after regulating, accounting for land use changes and climatic factors. The results revealed the adverse effects of the Shahrchai Dam on the hydrological indices. The analysis showed an increase in the average flow rate during the summer season and a decrease in other seasons. However, the combined effects of water transferring for drinking purposes, a decrease in permanent snow cover upstream of the dam, and an increase in water use for irrigation and agricultural purposes resulted in a decrease in the released river flow. Furthermore, the minimum and maximum daily flow rates decreased by approximately 85% and 65%, respectively, after the construction of the Shahrchai Dam. Additionally, the number of days with maximum flow rates increased from 117 days in the pre-dam period to 181 days in the post-dam period. As a concluding remark, the construction of the Shahrchai Dam, land use/cover changes, and a decrease in permanent snow cover had unfavorable effects on the hydrological regime of the river. Therefore, the hydrological indicators should be adjusted to an acceptable level compared to the natural state to preserve the river ecosystem. The findings of this study are expected to guide water resource managers in regulating the sustainable flow regime of permanent rivers.

Numerical study on flow instability in parallel helical tubes under ocean conditions

The superimposed coupling of flow oscillations generated by transient external forces under ocean conditions and flow oscillations in parallel helical tubes during two-phase flow instability may lead to more complex flow oscillation phenomena in parallel helical tubes. However, there is still a lack of understanding regarding the effect of ocean conditions on the two-phase flow instability within parallel helical tubes. The two-phase flow instability in parallel helical tubes under ocean conditions is numerically investigated in the present study. The effects of ocean conditions on the flow behavior and instability threshold in parallel helical tubes are studied with mass flux 200 kg/m2s and inlet subcooling within 5–70 °C. The results show that the mass flow rate decreases as the inclination angle increases. A larger rolling amplitude or shorter period increases the flow and temperature oscillation amplitude. Two characteristic frequencies are found in the natural circulation flow instability under the rolling motion. As the rolling amplitude increases, the compound flow oscillation amplitude is larger and more chaotic with a certain phase shift. The effect of stationary inclining on the flow instability threshold is rather significant than rolling effect. The results of the present study can serve as a significant reference for the operation and design of the helical-coiled once-through steam generator under ocean conditions.

Evaluation of drainage hydro credit implementation in the Vargem Grande stream basin in Montes Claros, Minas Gerais, Brazil

The urbanization process generally increases impermeable surfaces, reduces rain infiltration, increases the volume of surface runoff and the frequency of urban flooding. The Vargem Grande stream basin, object of this study, has a waterproofing of 64.94% of its area of about 18 km². The channel on Vicente Guimarães avenue where the basin's outflow is located has a drainage system that quickly directs the runoff to the bottom of the valley, where some flooding has already been observed. This article will assess the need to implement the Drainage Hydro credit, with the objective of reducing the growth of the waterproofing rate in the studied basin, from the damping of hydrographic peaks or the increase of permeable areas on the ground. Hydrographs were simulated with additions to every 10% of the current impermeable area until it equals to the area of the hydrographic basin. Hydrographs were also simulated with reductions to every 10% of the current impermeable area until they return to their natural flow conditions. From the obtained results, it could be verified that the implementation of this measure is a valuable strategy for the amortization of the hydrograph peaks, reducing the drained volumes.

Origins of complexity in the rheology of Soft Earth suspensions

When wet soil becomes fully saturated by intense rainfall, or is shaken by an earthquake, it may fluidize catastrophically. Sand-rich slurries are treated as granular suspensions, where the failure is related to an unjamming transition, and friction is controlled by particle concentration and pore pressure. Mud flows are modeled as gels, where yielding and shear-thinning behaviors arise from inter-particle attraction and clustering. Here we show that the full range of complex flow behaviors previously reported for natural debris flows can be reproduced with three ingredients: water, silica sand, and kaolin clay. Going from sand-rich to clay-rich suspensions, we observe continuous transition from brittle (Coulomb-like) to ductile (plastic) yielding. We propose a general constitutive relation for soil suspensions, with a particle rearrangement time that is controlled by yield stress and jamming distance. Our experimental results are supported by models for amorphous solids, suggesting that the paradigm of non-equilibrium phase transitions can help us understand and predict the complex behaviors of Soft Earth suspensions.

THE EFFECTS OF RUSSIA-UKRAINE WAR ON UKRANIAN ENERGY SECURITY AND EUROPEAN ENERGY SUPPLY SECURITY

Energy has still drawn substantial attention for both developing and industrialised countries in the aspect of the needs of their economies, businesses and households. For Ukraine as a resource-rich economy, energy security and the efficiency of the energy sector are the bases for the national security of Ukraine. It has been triggered by the annexation of the Ukrainian Crimea by Russia and Russia-Ukraine war today. All these problems have urged Ukraine to determine modern energy policy and a national energy security model in the light of the concepts of energy security in the 21st century. As it is known, the energy crises between Russia and Ukraine directly affect the security of European Union energy supply in the context of natural gas flows. The main argument of this study is as follows: The Russia-Ukraine war has severely affected the energy security of Ukraine and this situation has led the European Union countries to finally consider taking steps to diversify the supply and to prevent further deterioration of the EU energy supply security. In this context, the article will analyse how the effects of the Russia-Ukraine war on Ukrainian energy security will affect EU energy supply security.

A Novel Method to Integrate Hydropower Plants into Resource Adequacy Assessment Studies

This paper presents a novel methodology for modeling hydropower plants (HPPs) with and without pumping capability in resource adequacy assessment studies. The proposed method is based on the premise that HPPs should maximize their contribution to system adequacy within their technical constraints by using the energy reserves in their upper reservoirs without significantly deviating from their market schedule. The approach of this paper differs from the conventional operating policies for incorporating HPPs into resource adequacy assessment studies, which either adhere to a fixed market schedule or perform peak shaving, and are inelastic to real-time events or do not resort to realistic temporal correlations between natural water inflows on upper reservoirs and the water discharge needs to cover demand peaks, respectively. The modeling approach focuses on large-reservoir HPPs with natural inflows and is generic enough to deal with both stations incorporating pumping capabilities and those without. It utilizes the state-of-the-art Monte Carlo simulation technique to form the availability of system assets and determine the loss of load incidents. The market schedule and level of reservoir fulfillment for the HPPs are retrieved from a cost-optimal power system simulation algorithm executed offline before the application of the resource adequacy assessment. The effectiveness of the proposed methodology is demonstrated through its implementation in a case study of a power system experiencing different levels of adequacy, comparing the obtained results with various traditional HPP modeling methods from the literature.

Experimental testing and geometric optimization of a domestic cooker burning 80%Natural-Gas+20%Hydrogen

In urban pipelines, blending hydrogen into natural gas has been considered as an effective way of hydrogen usage to reduce carbon emission on household appliances. However, few studies, especially experimental ones are dedicated to address the characteristics of a typical domestic cooker due to the transition from natural gas to 20%hydrogen-enriched natural gas. This study experimentally investigated the changes in terms of the gas flow rate, flame temperature, heat transfer and emission characteristics of a domestic cooker as a result of such transition.Using a self-developed gas blending system, the flow rates of the both the mixed fuel and its components are obtained. The data shows that after blending hydrogen, the mixed gas flow rate becomes higher. Compared to the original cooker burning natural gas, hydrogen blending results in a decreased natural gas flow rate, leading to lower carbon emission. In addition, the thermal input to the cooker is lowered and hydrogen blending leads both the inner and outer combustion zones of the flame to shorten while the flame temperature to increase.As an attempt to optimize the performance of the cooker, the effects of wok stand height on heat transfer efficiency and NO/NOx/CO emissions are examined. It is found that the cooker fueled by 20%hydrogen-enriched natural gas exhibits lower heat transfer efficiency, higher NO/NOx emissions and lower CO emission. According to the fact that the heat transfer efficiency increases at lower wok stand height, the wok stand height is lowered from its original 7 cm–6 cm and 5 cm. The finding indicates that when the wok stand height is moderately decreased to 6 cm, NO/NOx emissions decrease and CO emission is only marginally increased. This study proposes that when natural gas is replaced by 20%hydrogen-enriched natural gas on a swirl flame cooker, the wok stand height can be slightly lowered to exploit the advantages of blended hydrogen combustion.

EXPERIMENTAL INVESTIGATION OF NATURAL CIRCULATING SOLAR ENERGY SYSTEM INCLUDING A PARABOLIC TROUGH SOLAR COLLECTOR

Abstract The most common natural flow water heating systems are in one-ended inclined pipes today. In this study, it is aimed to investigate the natural circulation solar energy system experimentally with parabolic trough solar collector. For this purpose, a natural circulation solar energy system including a parabolic trough solar collector that follows the sun in one dimension on the N-S axis in the outdoor environment has been established. Experiments were conducted on different dates. The radiation values coming into the opening of the moving collector were calculated. With the SolTrace program, it has been found that 56 % of this radiation can reach the vacuum tube glass pipe in the focus of the collector. In addition, the Rayleigh number was calculated for each experiment for the section of the glass tube close to the tank inlet, and it was monitored whether there was natural circulation throughout the experiment. As a result, the average Rayleigh number in the experiments conducted on 13 February, 31 March, 24 April, 23 May, 9 June, and 6 July was 1.4E+06, 7.6E+05, 7.8E+04, 2.2E+04, 3.1E+05, respectively. and calculated as 2.8E+05. In the experiments on May 23 and April 24, when the cooling system was open, it was observed that the Rayleigh number constantly dropped below the critical value. In other experiments, the situation is the opposite, and the natural flow is continuous.