Small Discharge Research Articles

High Supply, High Demand: A Fertilizer Waste Release Impacts Nitrate Uptake and Metabolism in a Large River

AbstractCurrent understanding of the relationship between nitrate (NO3−) uptake and energy cycling in lotic environments comes from studies conducted in low‐nutrient (NO3− < 1 mg‐N L−1), small (discharge <1 m3 s−1) systems. Recent advances in sensor technology have allowed for continuous estimates of whole‐river NO3− uptake, allowing us to address how the relationship between nutrient uptake and metabolism changes over time and space in larger rivers. We used a six‐month, controlled nitrogen (N) waste release into the eighth order Kansas River (USA) as an ecosystem level nutrient addition experiment. We deployed four NO3− and dissolved oxygen sensors along a 33 km study reach, from February to May 2018, to assess the spatiotemporal relationship between nutrient uptake and stream metabolism during the waste addition. Contrary to our prediction, we did not find evidence of uptake saturation despite an extreme increase in nutrient supply during winter, a period of generally lower biological activity. Although high uptake rates were observed across the study reach, they were uncorrelated to gross primary production. Overall, despite winter temperatures, NO3− uptake rates were high compared to small streams and rivers. We provide evidence that large rivers can be effective ecosystems for retaining and transforming nutrients, while showing that the fine‐scale mechanisms that regulate nutrient retention in large rivers are still largely unknown.

Experimental study on leakage detection of grassed earth dam by passive infrared thermography

The leakage of earth rock dams and dykes is characterized by time-space randomness, concealment and small initial discharge quantity. The time from the beginning of abnormal leakage to the break of a dyke is quite limited. The key to ensure the safety of earth rock dykes is to find and identify the leakages in time. Infrared thermography (IRT) has the advantages of fast visualization, strong mobility and wide coverage, so it is a good choice to detect the leakage outlet of earth rock dams and dykes in flood season. However, there are few reports on detailed research in this field. Fully simulating the real service conditions of earth rock dams in flood season, and considering the influence of turf covering, an earth dam model with leakage tunnels is built, then whole day infrared thermography tests of the outlet of the leakages are carried out at an outdoor laboratory in the lower reaches of the Yangtze River. More refined thermal imaging experiments are carried out in the afternoon and at night respectively. The better condition of using IRT to identify the leakage of earth rock dam is explored, and the thermal image spatial distribution characteristics and temporal varying regularity of the leakage outlets under the conditions of grassed and bare soil are also explored, which can provide some experience and reference for using IRT to identify the leakage of earth rock dams and dykes.

A novel 1DCNN and domain adversarial transfer strategy for small sample GIS partial discharge pattern recognition

Recently, convolutional neural networks (CNNs) have made certain achievements in gas-insulated switchgear (GIS) partial discharge (PD) pattern recognition. However, these methods rely on the availability of massive PD samples and how to apply the CNN constructed in the laboratory to the field GIS PD pattern recognition has become an urgent problem. To solve these problems, we propose a small sample GIS PD pattern recognition using one-dimensional CNN (1DCNN) and domain adversarial transfer learning (DATL). First, a novel 1DCNN is constructed to achieve high-accuracy classification using unbalanced samples, where the problem of traditional two-dimensional CNN’s dependence on sample size is solved. Second, DATL is used to realize on-site GIS PD pattern recognition using small samples containing some unlabeled samples. In the domain adversarial training, two domain classifiers are introduced to align the domain of the decision boundary, which achieves a suitable features migration and accurate classification of target domains. Through the construction of multiple experiments, we verified that the proposed method achieves 98.67% and >92% recognition accuracy in the source domain and target domain, respectively. Compared with the existing methods, the proposed method can realize satisfactory pattern recognition, which can provide strong support for the subsequent pattern recognition of GIS PD.

Analysis of Peukert and Liebenow Equations Use for Evaluation of Capacity Released by Lithium-Ion Batteries

The Peukert and Liebenow equations were obtained from experimental studies of lead–acid batteries. Currently, they are used to evaluate capacity released by batteries of other electrochemical systems (alkaline, lithium-ion, etc.), as well. In this paper, it is experimentally proved that for lithium-ion batteries, the Peukert equation can be used in two intervals of the discharge currents. The first interval includes currents from 0.2Cn up to the first inflection point of the experimental function of the battery capacity dependence on the discharge currents C(i). The second interval covers currents from the second inflection point of the experimental function C(i) up to the maximum currents that were used in the experiments. For some lithium-ion batteries, the range of low discharge currents, where the Peukert equation is applicable, is quite large and often completely covers the range of the discharge currents used in practice for these batteries. Therefore, many authors, when estimating the capacity of lithium-ion batteries, use the Peukert equation. However, the research in this paper shows that for lithium-ion batteries, the use of the Peukert equation is limited to the two discharge current ranges indicated above. Unlike the Peukert equation, the Liebenow equation can be used only in the range of small discharge currents from zero to the first inflection point of the experimental function C(i).

Hydrosedimentological Response to Estuarine Deepening: Conceptual Analysis

This paper describes the effects of anthropogenic deepening of tidal rivers in a conceptual way, with focus on tidal distortion and the residual transport of coarse sediment, driven by asymmetries in peak velocity. The rivers under consideration are fairly small, with small river discharge, and may have irregular hypsometry, with substantial intertidal area, or not. Residual sediment transport is driven by asymmetries in tidal velocity (horizontal tide), which is, however, difficult to establish in general. This paper discusses how and under which cases asymmetries in tidal elevations (vertical tide) can provide appropriate information on residual sediment transport. It is argued that deepening may induce a competition between an increase in tidal amplitude by amplification and a reduction in the asymmetry itself. Linear analysis shows that tidal asymmetry may show irregular behavior locally even for regular river configurations. It is therefore expected that these irregularities become larger in natural and engineered rivers. Analysis of local asymmetries may therefore be misleading in assessing the river's response to deepening with respect to the overall residual sediment transport and the river's morphology. Thus analysis of the overall morphodynamic response of a tidal river to tidal asymmetry, as affected by deepening, requires integration of the nonlinear effects along the entire river. It is argued that tidal asymmetry can be quantified by determining the difference in travel times of the high and low waters at any location within the river. This also implies that tidal water level variations and their asymmetries are governed by the entire tidal volume up-river of the cross section under consideration. River discharge further complicates the analyses by affecting residual water flows, effective hydraulic drag, tidal asymmetry, and mean water level. These effects reduce in response to deepening. However, salinity intrusion and gravitational circulation increase with deepening. We believe that assessing the (long-term) effects of deepening a fairway in a tidal river or estuary requires the use of process-based numerical models to account for all these nonlinear interactions, next to appropriate data collection. The current paper may help in analyzing and interpreting the numerical results.

Geometric model and pressurization analysis on a novel sliding vane compressor with an asymmetrical cylinder profile

The cylinder profile primarily determines the working performance of the sliding vane compressor. In order to increase the built-in volume ratio and compression ratio of the compressor, in this study, a novel asymmetrical cylinder profile composed of an exponential spiral was proposed, and then a novel asymmetrical sliding vane compressor was obtained. A geometric model of the proposed asymmetrical cylinder profile was established, and effects of power exponent n on the built-in volume ratio, area utilization ratio and acceleration of the cylinder profile were discussed. Furthermore, the working process of the proposed sliding vane compressor were simulated using structured dynamic grids, distributions of flow fields in the working chambers were obtained, and the gas pressure varying with the rotational angle was also analyzed. The study results show that the proposed sliding vane compressor has many remarkable advantages, small discharge volume, large built-in volume ratio and large compression ratio, compared with the traditional sliding vane compressor with the symmetrical cylinder of a circle profile under the same geometric size. The contents of this study are of great significance for promoting the development and application of sliding vane compressors.

Identifying the causes of waterlogging on people's perception towards a resilient community: a case study on Pabna Municipality, Bangladesh

PurposePabna is suffering from waterlogging problems from ancient times. The previous Drainage Master Plan was failed due to the lack of reflection of the general people of Pabna Municipality. As a result, this study focuses on identifying the causes of waterlogging in people's eyes. This paper will help the local authority and planners eradicate the waterlogging problem and build a planned and resilient community.Design/methodology/approachBoth primary and secondary data were used for the study. Present drainage pattern, topology climatic elements were collected from the journals, websites and Municipal Ingratiated Development Plan (MIDP), Pabna-2008. The sample size was 246, and this respondent was surveyed. By the survey, the people's perception of waterlogging was collected. For that, five independent variables and one dependent variable were determined. These variables were determined by previous studies, reconnaissance survey of the study area. It used multiple linear regression and the correlation method; the causes of waterlogging were determined.FindingsThe study found solid waste disposal into the drainage, absence of operation and maintenance system, small discharge capacity with blocked in the current drains, nonappearance of combined drainage network of roadside drains and unplanned drainage system as the leading causes of waterlogging from the perception of the people. Also found that the absence of operation and maintenance system, solid waste disposal into the drainage and unplanned drainage system as the influencing causes on small discharge capacity with blocked in the current drains.Originality/valueThis study has focused on people's perceptions rather than secondary data. That is why this study will significantly impact eradicating the waterlogging problem from the Pabna Municipality and will carry out the core problems without any bias. This will lead to a sustainable, planned and resilient community.

DIFFERENCES OF CULEX SPP AND AEDES SPP LARVAE MORTALITY RATES ON THE USE OF THEMEFOS

Eradication of the mosquito vectors that cause several diseases is still being carried out today where methods are still being developed. This research aims to identify the mortality rate of Culex spp. and Aedes spp. larvae for the use themefos or abate with sowed and wrapped of filter paper. The author uses quasi-experimental to observe that mortality. The design was devided into two groups, giving themepos/abate with a national dose of (1gr/10 liters of water) in 24 hours with threatment sowed and wrapped of filter paper through the analysis of varians/annova test to observe the varians of the time of mortality of Culex spp. and Aedes spp. larvae as well as probit analysis to see the probability of time of the larvae’s death.The result of this research is no defference in the mortality of Culex spp. and Aedes spp. larvae for the uses of themefos/abate with sowed and wrapped of filter paper. The authors suggestion is giving themefos or abate by wrapping filter paper preverably for larvae in a stagnant water such as Aedes spp larvae because it does not provide residual granules in water reservoirs used for human activities while the used of themepos/abate with sowed can also be used for a stagnant water or has a small discharge.

Head circumference, total cerebral volume and neurodevelopment in preterm neonates

ObjectivesTo assess the association of head circumference (HC) <10th percentile at birth and discharge from the neonatal intensive care unit (NICU) with neurodevelopment in very preterm (24–32 weeks’ gestational age)...

EXPERIMENTAL STUDY OF ENERGY DISSIPATION IN A SINGLE STEP CONDITION OVER A BROAD CRESTED WEIR

This research study the experimental performance of broad-crested weir with single-step by introducing U/S and D/S round-nose and analysing the parameters that have effect on the shape of the step and their effects on the flow characteristics and energy dissipation (E%) downstream (D/S) of the weir. Furthermore, empirical relations for E% and flow rate due to the influencing factors were derived. The results showed that the weir model with = 1.000 gives a higher E% in comparison with other weir models. Flow regimes were observed i.e nappe flow for small discharges, transition flow for intermediate discharges and skimming flow for higher discharges. Two model equations were obtained, the first to dteremine the flow rate over the weir models and the second relation to estimate E% in terms of, and Froude number. The model () can be used in the design of prototype weirs in terms of energy dissipation

Performance of a surface corona preionized mini-TEA CO2 laser

A surface-wire corona preionized miniature transversely excited atmospheric CO2 laser was evaluated. The corona pre-ionizer was constructed from alumina (Al2O3) ceramic tube and a fine wire stretched along the surface of the tube. When this extremely efficient yet comparatively inexpensive pre-ionizer was applied to the laser, output pulse energy of 230 mJ with a pulse duration of ∼70 ns (FWHM) was obtained from a small discharge volume of 50 cm3. This energy output was found to be higher than that obtained from a spark preionized laser with the same discharge volume. Moreover, the discharge stability was also found to improve drastically. These results can therefore be used as a reference when developing full-scale corona pre-ionized laser systems.

Experimental study on electrostatic discharges from a metal protrusion inside a silo during continuous loading of polypropylene powder

In this study, the electrostatic discharges from a metal protrusion existing inside a conical-cylindrical silo during continuous loading of polypropylene powders (PP, 3 to 4 mm) were experimentally investigated. A pilot-scale silo connected to a pneumatic powder transport facility was used while all parts were electrically grounded. The metal protrusion used in this study had a diameter of 4 cm. The silo was continuously loaded with PP powders at a mass flow rate of 0.68 kg/s to a total mass of approximately 800 kg. An image intensifier unit was used to observe the electrostatic discharges generated from the metal protrusion, and a current probe attached to an oscilloscope was used to measure the discharge amount (Q [nC]). As for the results, a multiplicity of small electrostatic discharges (brush discharges) from the protrusion was observed. The electrostatic discharge from the protrusion during PP powder loading clearly developed at the 391 s mark, when approximately 270 kg of the powder had been loaded. In addition, a difference was observed in the electrostatic discharges before and after the protrusion was embedded in the accumulated powder. That is to say, after the metal protrusion was embedded in the accumulated powder, the electrostatic discharges were stronger than when the protrusion was not embedded. As well, the Q after the immersion of the metal protrusion in the accumulated powder was several times larger than that when the protrusion was out. Strong broad bulk surface discharges clearly appeared after the protrusion was fully immersed in the powder.

Torque and Power Testing of the Pelton Turbine

Energy sources that can be renewed in Indonesia according to Asean energy sources, one of which is microhydro that uses water as a source of energy from a turbine. The potential energy of water is converted into kinetic energy in the nozzles. The water coming out of the nozzle that has a high speed hits the turbine blade. After hitting the blade direction the flow velocity changes so that the momentum changes (impulses) so that the turbine wheel will rotate. Pelton Turbines are impulse turbines which consist of a set of road blades that are rotated by a jet of water sprayed from one or more devices called nozzles. Pelton Turbine is one of the most efficient and suitable types of water turbines used for high head and small flow discharge. Pelton turbines have several advantages including turbine efficiency which is relatively stable at various changes in flow discharge. The purpose of this writing is to find out and provide insight into the torque and power of the Pelton turbine and the effect on the valve openings that are varied.

Carbon material with high specific surface area and high pseudocapacitance: Possible application in supercapacitors

A new carbon material (NCM-R) was studied, which has a number of unique properties: a high specific surface area according to the BET (S BET = 3270 m 2 /g), a high micropore volume (~1.7 cm 3 /g), and a very high specific capacity of 870 F/g. The NCM-R is obtained by carbonizing a mixture of dextrin and graphene oxide and activating the carbonizate with potassium hydroxide. Based on the charging and discharge characteristics, it was established that the NCM-R is a promising material for supercapacitor electrodes with very small (diapason of a few seconds) discharge times and anodes of asymmetric supercapacitors with high specific energy. It is assumed that a large specific capacity is due to the reversible chemical attachment of hydrogen atoms to the carbon skeleton when the NCM-R charge is in the cathode region of the potentials. • Alkaline activation of a carbonized GO/dextrin mixture was used for obtaining of NCM-R. • NCM-R has a specific surface area 3270 m 2 /g following the BET method. • NCM-R has a high micropore volume (~1.7 cm 3 /g). • A specific capacitance of NCM-R (870 F/g) is due to the intercalation of hydrogen into the carbon skeleton. • The average specific capacitance of the double electric layer in NCM-R was only 210 F/g.

Prototype design of waterwheel micro hydro power plants for small water discharge

The findings of this study was the Prototype Model of Micro Hydro Power Plant (MHPP) for small water discharges (less than 10 Liters per Second), namely MHPP waterwheel and the Speed Converters from waterwheel to Dynamos, named “Converters” MHPP. This study was aimed to produce a prototype design of a wind turbine-based MHPP for small water discharge. This study used an engineering-based approach to the design of prototype MHPP. The design of the prototype MHPP for small water discharges (less than 10 liters per second) consists of 6 components, a wheel diameter of 4-5 meters, the turning machine from a pinwheel to a dynamo given the name “converter”, Dynamo, House where the prototype MHPP, Conductor Network of MHPP to homes, and safety tanks and waterways.

Numerical Study of Discharge-Head Relationship of Piano Key Weirs for Low Heads

Piano Key Weirs (PKW) is a free-flowing weir, and an improvement over the labyrinth weir family. PKW has higher discharge for the same head as compared to other types of weirs. They tend to reduce the upstream submergence in reservoirs or other flow systems and can be effectively used for flood risk mitigation. CFD studies have been carried out earlier but mostly for H/P (Total head to height ratio) greater than 0.1. The present paper investigates the use and validation of Computational Fluid Dynamics (CFD) for modeling Open Channel flows over common hydraulic structures such as PKW for small discharges with the entire range of head to height ratio h/P from 0.035 to 0.1, where h is not the total head upstream of PKW but the head measured at the crest of PKW. The numerical results have been validated with experimental results. Since the discharge is minimal surface tension force has been incorporated in the numerical model. The numerical model is a half PKW unit model with the same geometrical parameters as the experimental setup from Literature. The results show that CFD simulations can reproduce flow depths near PKW with reasonably good accuracy. The present paper compares the head obtained from CFD with that of empirical formula in the Literature but with head measured at the crest of PKW. Investigation of water surface profile and velocity profile near the upstream of PKW has also been carried out.

Effect of Water Cushion on Dynamic Pressures at Impingement Area

A free-fall water jet released from a spillway may cause significant scour on the downstream river reaches due to high dynamic pressures. Energy dissipators are generally used at the downstream of a spillway to disperse the energy of the water jet. In case of low air concentration, the jet may hit the river bed with high dynamic pressure heads that can cause significant scour adjacent to the dam body. The scour can cause significant stability problems on the dam body. To prevent the phenomenon, water cushion can be a practical tool to reduce the jet impact at the impingement area. In this study, the effectiveness of the water cushion is inspected by measuring the dynamic pressure variations against different discharges and varying water cushion levels. The results of the experimental study show that dynamic pressure reduction is reversely proportional to the water cushion level until a certain discharge. Then, water cushion level changes become meaningless, especially for small discharges.

Design of an edge tapered 915 MHz/TM021 microwave plasma reactor by numerical analysis

Microwave plasma reactor is often of particular interest due to their wide range of industrial applications, especially in high-end manufacturing. However, there exist problems of unstable plasma and small discharge area in conventional microwave reactors at 2.45 GHz. An edge tapered 915 MHz/TM021 microwave reactor evolved from reactors at 2.45 GHz is presented to improve the strength, area, and uniformity of microwave field for plasma applications. An electromagnetic model of a microwave reactor with the new coupling antenna composed of a tapered platform and a coaxial inner conductor is simulated. The simulation results show that the electric field strength in the new reactor with a size optimized coupling structure is more concentrated compared to similar reactors. A 2D axisymmetric hydrogen plasma discharge model based on self-consistent fluid simulation of this new reactor is presented. The obtained results show that this kind of model can lead to a better understanding of the physical processes occurring in these kinds of microwave reactors.

Using lower and upper baffle arrangements to enhance sedimentation tank performance

Traditional sedimentation tanks are massive structures that needs require extensive detention times to allow the separation of particles from suspension by gravity. Many researchers have proposed methods of enhancing sedimentation efficiency, including changing the geometry of tanks by installing barriers at the bottom of the basin, in order to reduce demand for chemical processes, which require trained operators to determine the appropriate doses of coagulants. The aim of the current research was make the flow route longer and to distribute suspension over various sedimentation tank compartments in order to increase residence time and thus enhance sedimentation, with effects judges based on calculating the turbidity, density, and viscosity, Froude number (Fr), Reynolds number (Re), settling velocity (vs), detention time (D.T.), height of sludge (hs), and sediment removal. The theoretical aspects were supported by the collection of practical results through laboratory testing that showed that the best Fr, Re, and hs occurred in zone 3, where the opening height of the central baffle created a short-circuit that scoured the deposited particle, while the best turbidity removal occurred with the smallest discharge. The evidence overall suggested that adding both lower and upper baffles improves the performance of sedimentation tanks because this arrangement achieves two essential goals: lengthening the track and damping or calming the flow within the settling zone; however, this only occurs if the vertical upper baffle is situated in a suitable location.

Characteristics of Duwet Karst Spring Based on Baseflow Index Assessment and its Potential in Fresh Water Supply

&lt;p&gt;&lt;em&gt;This study aims to determine the potential of Duwet springs and their availability for supplying fresh water to the surrounding community. we use hydrographs to analyze aquifer characteristics. To analyze the hydrographs, we use water level and spring discharge data. Automatic Water Level Record (AWLR) records water level data for 1 dry season and 1 rainy season every 15 minutes. We use the volumetric method to measure the spring discharge 14 times. We compare the base flow and demand over a year to analyze the potential for fresh water. The results show that the Stage discharge rating curve y = 0.0002e5,453x with R² value of 0.87. Duwet Springs is a perennial spring that has a small discharge (class VI). The largest discharge ever recorded was 0.69 L/s (March 7, 2020) and the smallest recorded was 0.12 L/s (August 21, 2020). BFI value varied between 0.05 and 1 with mean 0.801. The total base flow is 2490675.734 L (rainy season) and 1563419.873 L (dry season). These springs are sufficient for 75% of the rainy season and 84% in the dry season. This indicates that the existence of Duwet springs is very important for the surrounding community.&lt;/em&gt;&lt;/p&gt;