Power Equation Research Articles

Novel Inversion Algorithm for the Atmospheric Aerosol Extinction Coefficient Based on an Improved Genetic Algorithm

As an important atmospheric component, aerosols play a very important role in the radiation budget balance of the earth–atmosphere system. To study the optical characteristics of aerosols, it is necessary to use an inversion algorithm to process the lidar return signal to obtain both the aerosol extinction coefficient and the backscattering coefficient. However, the lidar return power equation is ill-conditioned and contains two unknown parameters, meaning that traditional inversion algorithms must be solved by adopting certain assumptions (e.g., a uniform atmosphere and the lidar ratio), which to a certain extent can seriously affect the inversion accuracy. Here, to improve the accuracy of the aerosol extinction coefficient inversion, an inversion method based on an improved genetic algorithm is proposed. Using the U.S. Standard Atmosphere model and the return power equation, the aerosol extinction coefficient and the backscattering coefficient are independent variables that randomly provide initial values to simulate the theoretical lidar power. Then, the genetic algorithm is used to approximate the theoretical lidar power to the measured lidar return power with height; when the two are infinitely close, the values of the corresponding two independent variables (i.e., the extinction and backscattering coefficients) are inverted. Experiments performed to compare the different effects between a simple genetic algorithm and the improved genetic algorithm showed the proposed method capable of inverting the aerosol extinction coefficient without reliance on traditional inversion methods, representing a novel approach to the inversion of the aerosol extinction coefficient and the backscattering coefficient.

Broadening Design and Optimization of High-Efficiency Region for a Dual-Mechanical-Port Flux-Switching Permanent Magnet Motor

In this article, a dual-mechanical-port flux-switching permanent magnet (DMP-FSPM) motor is studied for achieving high-efficiency design and optimization. The key of this study is to propose an optimization design approach for broadening high-efficiency region, where the motor efficiency fitting curve and the speed–torque envelope curve are combined. First, the efficiency function is established according to the motor power and loss equation. Then, high-efficiency region boundary points are obtained by combination of the fitted efficiency curve and speed–torque envelope curve. Next, the efficiency of representative operating points is determined and optimized to realize the broadening of motor high-efficiency region. Finally, the effectiveness of the proposed method and the studied DMP-FSPM motor is verified by the study results and experiment test.

Study of alpha particle concentration effects as the ash of deuterium-tritium fusion reaction on ignition criteria

In this study, the ignition criteria in the International Thermonuclear Experimental Reactor (ITER) associated with helium concentration is investigated. The main fuels used in this study are deuterium-tritium. Helium as the ash of deuterium-tritium reaction cannot be avoided. In this work, the effects of alpha particle concentration on plasma operation are investigated. The calculations were performed by using zero-dimensional power and particle balance equations. The results of our calculations show that the temporal evolution of alpha particle concentration becomes constant at 0.14. Then, ignition criteria and saddle points have been studied in n e τ E −T, and −T planes for different alpha particle concentrations.

PREDICTION OF POPULATION DISTRIBUTION IN 2030 USING THE INTEGRATION OF THE CA-ANN LAND COVER CHANGE METHOD WITH NUMERIC EXTRAPOLATION IN KARAWANG-BEKASI, INDONESIA

Abstract. Population growth continues to increase every year. It is recorded that in 2022 the world population will reach 7,953,952,567 or an increase of 1% from 2021. The increasing number of residents encourages land use/land cover changes to become settlements. In addition to changes in land use/land cover, there is also population mobilization from one place to another. This population movement will coincide with developments that will occur in the area. Monitoring population distribution is necessary to have no concentration in only one area. Areas with too dense a population will cause many problems such as the emergence of slum buildings, congestion, and flooding. In this case, the population density is centralized due to poor regional planning. The absence of prediction of future population distribution is one of the reasons why urban planning in the future is not optimal. This study aims to predict the distribution of the population in 2030. In predicting the distribution of population in 2030, it integrates the prediction of land use/land cover in 2030 with the prediction of the population in 2030. In predicting land use/land in 2030, land use/land in 2005 and 2010 is used as the primary data for change prediction. The method used to predict changes in land use/land cover is the CA-ANN method by considering the driving factors of changes in the form of altitude, distance from the river, and distance from the road. Predicting the population of 2030 will be done by extrapolation using the three mathematical equations approach, they are linear, exponential, and power equation. The results of the prediction of land use/land and population in 2030 are then used to predict the population distribution in 2030. From the results, In the 2030 there was an increase in the class of settlements which reached an area of 745,169 Km2 with the overall accuracy of the land cover model reached 82%. The largest population projection come from exponential equation that until 13024668 in 2030. The model population distribution in 2030, show that there is no significant different between three projection model to be used in model population distribution 2030. It is hoped that this research can be a reference for policymakers in planning sustainable urban development.

Запасы и структура фитомассы древостоев северотаежных сосняков Республики Коми

The research aims at estimating phytomass reserves of northern taiga green-moss and sphagnum pine forests growing in the Komi Republic. The study was carried out in pine forests at the Zelenoborsk forest research station of the Institute of Biology of Komi Science Centre of the Ural Branch of the Russian Academy of Sciences (IB Komi SC UB RAS) in 2016–2019. We analyzed sample trees data and derived power equations of the dependence of the individual fractions weight on the stem diameter at the breast height (1.3 m) for the main forest-forming species (pine, spruce, larch, and birch) of green-moss and sphagnum forest are characterized by rather large phytomass reserves, 136–211 t/ha. While in sphagnum pine forests there are 89–96 t/ha of phytomass. Despite the admixture of other wood species, the leading pool is represented by pine trees, and the main fraction (46–56 %) is wood of stem. The input of stem wood and stem as a whole (bark and wood) is greater in green-moss pine forests compared to sphagnum pine forests, while the share of roots in these two types is approximately the same. Participation of tree crowns (needles/leaves and branches) in the total phytomass reserves of pine stands on automorphic soils is significantly lower (17 % on average) than in communities on semihydromorphic and hydromorphic soils (22 % on average). The relatively greater mass of needles and leaves resulted in a high LAI, which varied from 8.8 to 17.8 and from 7.7 to 9.8 ha/ha, respectively, in green-moss and sphagnum pine forests. We found a high reliable (R = 0.88; p = 0.004) relationship between LAI and the tree basal areas sum, whereas it is statistically insignificant with density and wood supply. The conversion factors were calculated to convert timber volume into phytomass reserves of both individual fractions and species as a whole. The presented data are useful for assessing the productivity of pine ecosystems in different growing conditions during forest monitoring (including remote sensing methods) and also when planning forest management measures in order to increase the productivity of pine forests.

Jazz Places: How Performance Spaces Shape Jazz History

Jazz Places: How Performance Spaces Shape Jazz History

A Method for Directly Extracting the Jacobian Matrix of the Power Flow Equations of a Power System in Polar Coordinates

This paper presents a method to directly extract the Jacobian matrix of a power system’s power flow (PF) equations in polar coordinates (termed as DEJMP method). This method is designed to reduce the computational complexity of the extraction process and improve the computational efficiency of the relevant PF algorithm. Direct extraction of the Jacobian matrix from the complex power equation in polar coordinates precludes an increase in both the number of procedural steps and the computational expense, which is a problem associated with the conventional PF (C-PF) algorithm due to its requirement that the derivatives of the active and reactive bus power equations be taken in separate steps. The DEJMP method avoids the trigonometric calculations used in the conventional method for computing the Jacobian matrix, resulting in a significant increase in computational efficiency. In addition, simulation results obtained for IEEE-300, S-1047, S-2383, and S-9241 bus systems validate the efficiency of the DEJMP-based PF algorithm. The DEJMP-based PF algorithm requires more than 20% less time to calculate the PF than the C-PF algorithm. This decrease in computing time is more pronounced for large systems.

Evaluation of Haemolytic Activity in Smokers by Using Non-Linear Regression.

<b>Background and Objective:</b> Smokers are poorly protected against pathogens. Many studies have focused on the concentrations of complement components in comparison to smokers while ignoring the practical sequencing of complement components. There are numerous methods for estimating haemolytic activity (CH50%), all of which need a large number of samples and dilution, in addition to a typically expensive test kit. This novel study attempts to use statistical analysis and use the non-linear regression 'power equation' to extract the CH50% by using 5 serum dilutions only. <b>Materials and Methods:</b> The power equation can multiply the five practical dilutions into hundreds of mathematical loops within the sample range. The (CH50%) value is highly accurate for both the study and comparison sample and was evaluated in11 smokers. <b>Results:</b> The results were contrasted with a control composed of 11 individuals, matched by age and sex. The power equation showed a 6.48% significant reduction in (CH50%) in smokers compared with non-smokers, where a 17.54% reduction was observed. <b>Conclusion:</b> The current study suggests a decrease in the function of the classical complement pathway (CH50%) in smokers. On the other hand, the study provided a new statistical pattern, linking the practical values with default values within the range of dilution and formulating an equation that could be used to extract the value of CH50% with high accuracy.

Görüntü analizi ile bütün ve fleto sazanların ağırlık ve renk değerlendirmesi

Weight estimation of whole fish and fillets, and skin color of whole fish and fillet meat colors of the male and female scaled and mirror carp (Cyprinus carpio) were evaluated by image analysis. After measuring the weight of 10 scaled and 10 mirror carp and their fillets, pictures of both sides of whole fish, and meat side of fillets were taken in a light box. The relationship between weight (W) and view area (V) was calculated by linear (W = A + BV), and power (W = A VB) equations. According to the power equation B values, scaled and mirror carps showed positive allometric growth in culture conditions. Statistically, there was no significant difference between the parameters of whole fish left and right sides, as well as whole fish gender. The same was true for right and left fillets, and female and male fish fillets. For both left and right sides scaled and mirror carp had no difference between average L*, a* and b* values (P>0.05). Also, there was no difference between average L*, a* and b*values of male and female of scaled and mirror carp fillets (P>0.05). Image analysis can be used to determine the size, weight, view area and skin and meat color of two carp species and their fillets.

4DPRR- Index for predicting mortality in COVID-19 ARDS

Abstract Background Mortality in ARDS was reduced significantly after the introduction of the low tidal volume ventilation strategy. It has been recently shown that lung-protective ventilation strategies should primarily target driving pressure rather than Vt and that ventilator induced lung injury is not just dependent on tidal volume but also other factors like respiratory rate and driving pressure. Ventilator induced lung injury is also thought to be dependent on the amount of energy transferred by the ventilator to the patient which in turn is dependent on tidal volume size (VT), plateau pressure (Pplat), respiratory rate (RR). Mechanical power can be calculated accurately through power equations which can increase their applicability in clinical practice. One simple composite equation (driving pressure multiplied by four plus respiratory rate [4DPRR]) has been recently suggested as a simple surrogate for the power equation. This equation also doesn’t include PEEP as it has been theorized that it is the only elastic dynamic component of driving energy which affects the outcome and not the elastic static component (i.e., PEEP) and the resistive power (related to flow and airway resistance). Objectives To assess the mechanical power as measured by 4DPRR in mechanically ventilated patients who have moderate to severe COVID-19 ARDS. Methods: We obtained data on ventilatory variables and mechanical power from the patients who were admitted with moderate to severe COVID ARDS in our hospital from March 2021 to June 2021. Results We included 34 patients (28% women; mean age, 57 ± 17 yrs.). The average ΔP was 21.44 ± 3.98 cmH2O, the RR was 23.8 ± 3.84 breaths/min, and the mean driving pressure was 21.4 cmH2O. 28% (n = 10) of patients expired. There was no significant association of 4DPRR (P 0.72), Pplat (P 0.79).and RR (P 0.21) with mortality as predicted by area under ROC curves. Conclusions Driving power and plateau pressure were associated with mortality during controlled mechanical ventilation in COVID ARDS, but a simpler model of mechanical power using only the driving pressure and respiratory rate was found to be a poor predictor of mortality. Keywords: COVID-19, ARDS, Mechanical power, Driving pressure, Plateau pressure

Mechanical power in AVM-2 versus conventional ventilation modes in a normal lung model: A bench study

Introduction Recent studies suggested that the energy delivered by the mechanical ventilator to the lungs termed the mechanical power can induce and increase the risks of ventilator induced lung injury. The components of the mechanical power include the variables delivered by the ventilator: tidal volume, respiratory rate, inspiratory flow, airway pressure. Adaptive Ventilator Mode-2 (AVM-2) is a pressure-controlled mode with an optimal targeting scheme based on the inspiratory power equation that adjusts the respiratory rate and tidal volume to achieve a target minute ventilation. This mode conceptually should reduce the mechanical power delivered to the patients and thus reduce the incidence of ventilator induced lung injury. Methodology A bench study using a lung simulator (TTL, Michigan Instruments, Michigan, USA) was conducted. We constructed a passive single compartment normal respiratory mechanics model with compliance of 50 ml/cmH2O, and resistance of 10 cmH2O/L/s, with IBW 70 kg. We compared three different ventilator modes: Adaptive Ventilation Mode-2 (AVM-2), Pressure Regulated Volume Control (PRVC), and Volume Controlled Ventilation (VCV) in four different scenarios: 2 levels of minute ventilation 7 and 10.5 Lit/min (Experiment 1 and 2 respectively), each with 2 different PEEP levels 5 and 10 cmH2O (Experiment A and B respectively) termed Experiments 1A, 1B, 2A, and 2B respectively. The AVM-2 mode automatically selects the optimal tidal volume, and respiratory rate per the dialed percent minute ventilation with an I:E ratio of 1:1. In the PRVC, VCV we selected target tidal volume 6ml/kg/IBW (420 ml), and respiratory rate adjusted to match the minute ventilation for the AVM-2 mode. I:E ratio was kept 1:2 to avoid intrinsic PEEP. The study was conducted using a bellavista™ 1000 e Ventilator (Vyaire Medical, Illinois, USA). The mechanical power delivered by the ventilator for each mode was computed and compared between the three modes in each experiment. Statistical analysis was done using Kruskal-Wallis test to analyze the difference between the three modes, post HOC Tukey test was used to analyze the difference between each mode with the confidence intervals, P < 0.05 was considered statistically significant. Results There were statistically significant differences between all the three modes regarding the ventilator delivered mechanical power. The AVM-2 mode delivered significantly less mechanical power than VCV which in turn was less than PRVC. Experiment 1A: AVM-2 8.76 土 0.05, VCV 9.78 土 0.04, PRVC 10.82 土 0.08, P < 0.001 Experiment 1B: AVM-2 11.27 ± 0.09 VCV 12.81 ± 0.05, PRVC 13.88 ± 0.06, P < 0.001. Experiment 2A: AVM-2 14.76 ± 0.05, VCV 15.79 ± 0.05, PRVC 18.29 ± 0.07, P < 0.001, Experiment 2B: AVM-2 18.76 ± 0.04, VCV 20.56 ± 0.04, PRVC 21.17 土 0.03, P < 0.001. Discussion AVM2 mode delivered less mechanical power compared to two conventional modes using low tidal volume in a normal lung model. This might reduce the incidence of ventilator induced lung injury. Results need to be validated in more clinical studies.

The Epidemiology of Sexual Violence in Nigeria

This paper investigated the epidemiology of sexual violence in Nigeria. Sexual violence has been considered as an “imposed sexual act with physical force” caused by lack of consideration of other’s right. In Nigeria, violence against women is becoming an increasingly recognized pandemic issue necessitating eradication and elimination. It occurs in various forms with resultant physical, sexual or psychological consequences. However, there is still denial and paucity of literature about the magnitude and pattern of this problem in Nigeria. Sexual violence against children and women brings with it long-term, both psychiatrically and socially. Apart from sexual gratification itself, sexual violence against women in Nigeria is a result of unequal power equations both real and perceived between men and women and is strongly influenced by cultural factors and values. The findings and results of this paper will be helpful to girls and women terms governing sexual violence and how to remain safe from been violated. Therefore, this paper systematically reviewed some related literature on sexual violence, contexts of sexual violence and examined it forms, the risk factors associated with sexual violence and the way out of sexual violence.

Estimation of Sound absorption Coefficient from the Sound Power

Sound absorption measurements were carried out in the reverberant room in accordance with ISO354. The present paper gives an experimental technique to estimate the sound absorption coefficient of a material based on the sound power in the reverberation room according to ISO 3741. This is in order to be able to calculate the sound absorption coefficient of the material needed to reduce the sound pressure levels in the room. Depending on Newton’s (iteration) method inferred equivalent sound absorption area and sound absorption coefficient will be obtained from the sound power equation Measurements were taken on four different materials to test the method's validity (wood, rubber, Gypsum, and polyurethane sponge). For boor sound-absorbing materials, acceptable results were obtained for the corresponding sound absorption area. Due to the mutual dependency on both the properties of the material and the parameters of the reverberant environment, there was an unstable discrepancy in the results of the sound absorption coefficient for high sound-absorbing materials. The relative standard deviation for sound absorption was 0.00 while the uncertainties for sound power was 0.7dB

Simple, accurate calculation of mechanical power in pressure controlled ventilation (PCV)

BackgroundMechanical power is a promising new metric to assess energy transfer from a mechanical ventilator to a patient, which combines the contributions of multiple parameters into a single comprehensive value. However, at present, most ventilators are not capable of calculating mechanical power automatically, so there is a need for a simple equation that can be used to estimate this parameter at the bedside. For volume-controlled ventilation (VCV), excellent equations exist for calculating power from basic ventilator parameters, but for pressure-controlled ventilation (PCV), an accurate, easy-to-use equation has been elusive.ResultsHere, we present a new power equation and evaluate its accuracy compared to the three published PCV power equations. When applied to a sample of 50 patients on PCV with a non-zero rise time, we found that our equation estimated power within an average of 8.4% ± 5.9% (mean ± standard deviation) of the value obtained by numerical integration of the P–V loop. The other three equations estimated power with an error of 19.4% ± 12.9% (simplified Becher equation), 10.0% ± 6.8% (comprehensive Becher equation), and 16.5% ± 14.6% (van der Meijden equation).ConclusionsOur equation calculates power more accurately than the other three published equations, and is much easier to use than the only previously published equation with similar accuracy. The proposed new mechanical power equation is accurate and simple to use, making it an attractive option to estimate power in PCV cases at the bedside.

Dynamic particle accumulation on a single wire in transverse field pulsating high gradient magnetic separator

High gradient magnetic separation (HGMS) is widely used to separate feebly magnetic materials. A dynamic buildup equation R4=Et+1 has been built to reflect the change of buildup radius with time and predict these realistic separation processes. In recent years, with the successful application of pulsating slurry in HGMS, the original equation has been increasingly reconsidered to investigate the effect of pulsating slurry. This study explores the particle dynamic accumulation law on a single wire in the transverse HGMS configuration with pulsating slurry. The theoretical expression of the variation of accumulation area with time: Sa2m=Et+1 is derived following the particle trajectory equations. The investigated results of a TV camera system indicate that the realistic buildup process in transverse pulsating HGMS satisfies the derived power equation. The power exponent m is approximately independent of particle size, magnetic field strength, and wire diameter, and it has a positive linear correlation with the pulsating frequency. Similar to previous studies, m is equal to 4 when without pulsation. The coefficient E depends on the force acting on the particle and is related to all parameters affecting the acting force and the power exponent m.

EUROPEAN UNION AND THE UNITED STATES OF AMERICA: AN ECONOMETRIC INVESTIGATION ON THE PARADIGM SHIFT IN THE GDP’S GROWTH RATE TREND

The recent war between Ukraine and Russia is yet another instance that emphasizes that economic overdependence may destroy the economic fabric of a nation. Taking this premise into consideration, this study aims to examine the long-term and short-term connection between the European Union and the United States GDP growth rates using tools like linear regression, Granger causality test, and impulse response function. Quarterly GDP figures of the European Union and the United States were taken for the period spanning 22 years, starting from quarter 2 of the financial year 1998-1999 to quarter 4 of the financial year 2018-2019. The Regression model and the Granger Causality test prove that the United States’ GDP growth rate is influenced by that of the European Union in the short-run as well as in the long-run, but the EU’s GDP is independent and does not follow the former. The possible explanation can be the trade surplus of the European Union over the United States in the recent past. Hence, the authors are of the opinion that a much more balanced trade between these two powerful economies would ensure the stabilization of the global trade and stability of the global power equation.

Reactivity estimation based on the linear equation of characteristic time profile of power in subcritical quasi-steady state

ABSTRACT The reactivity was estimated from a time profile of neutron count rate or simulated data in a quasi-steady state (QSS) after a sudden status change of reactivity or external neutron source strength. The estimation was based on the equation of power in subcritical QSS. The purpose of the study is to develop the method of timely reactivity estimation from complicated time profile of neutron count rate. The developed method was applied to the data simulating neutron count rate created by using one-point kinetics code, AGNES, and Poisson-distributed random noise. It was also applied to the transient subcritical experiment data measured by using transient experiment criticality facility. The result shows that the difference of the estimated and reference values was within about 5% or less for for simulated data and within about 7% or less for ρ$ ≃1.4 and for the experimental data. The possibility of the reactivity estimation several 10 seconds after the status change was also shown.

HOLISTIC RISK INDEX FOR DECISION-MAKING IN MANAGEMENT OF RUST Hemileia vastatrix IN COFFEE PLANTATIONS IN HONDURAS

One of the diseases that most affect coffee plantations (Coffea arabica) is the fungus Hemileia vastatrix, which causes rust. The lack of a decision-making method with a holistic approach limits the effective management of this disease. Therefore, this study aimed to determine the Holistic Risk Index (HRI) for rust in coffee-growing zones of El Lago de Yojoa, El Paraíso and Olancho, Honduras. First, a participatory diagnosis of coffee industry was implemented; surveys were conducted to determine the socioeconomic status of 43 coffee producers, also their coffee farms were sampled. The diagnosis indicated that deficient management of the coffee plantations, the incidence of pests and a precarious economy for coffee growers were the most important problems. One threat variable (leaves with rust); three vulnerability variables (altitude, coffee variety and shade); and three response capacity variables (technification, harvesting and productive coffee trees) were identified. The HRI and resilience were related by means of a power equation and from that result the criteria for categories were determined. When comparing the three coffee-growing zones with a multivariate analysis of variance and a canonical discriminant analysis for the set of HRI component values, the El Paraíso coffee-growing zone was different from the Lago de Yojoa zone, but these two zones did not differ from the Olancho zone. The same result was found for the response capacity, where the harvest and technification variables had a greater influence in El Paraíso and the productive category variable of coffee trees was more important in Olancho. Finally, a work plan was proposed to reduce the risk and increase the resilience of producers to rust.

Limit analysis of shallow tunnels collapse problem with optimized solution

The aim of this study is to understand the collapse mechanism of a shallow tunnel based on the upper bound analysis method, considering the variational approach for the problem with variable endpoints. The virtual power equation of upper bound theorem and Hoek-Brown criterion are combined to analyze the overlying rock mass, and the expression of collapse curve is obtained. Compared with the collapse curves solved by the variational method of the fixed endpoints problem in other studies, the advantage of this method is to consider the effect of the variable endpoints on the collapse curve, which is able to model the problem in a more realistic manner. The results show that the collapse curves obtained by the variational method of the variable endpoints problem are smaller than that of the existing study which are solved by the variational method of the fixed endpoints problem. The results also indicate that the width of excavation needs to be sufficiently small and the support for the overlying rock mass needs to be sufficiently large to prevent collapse. In general, these results will help to provide safe design and construction guidance for engineering practice.

GENERATING RATING CURVE AND RATING TABLE OF GOLARCHI MINOR

Hydrologists must have huge theoretical and practical knowledge of irrigation networks such as rivers, canals, streams, channels, and minors. Because whole irrigation system relies on a gauge and discharges relationship which is essential for controlling floods, water resource management, and hydrologic modeling. The true and consistent figures of flow rate in the irrigation system are important for irrigation water efficiency. Mostly, Hydrologic modeling activities like hydraulic structures, designs, and management of surplus water in canals are subjected to the flow of irrigation water which is derived from the rating curve (RC). The managing of irrigation water in the system must be essential for crop water requirements and estimation of seepage losses. Thus, to fulfill the objectives, field activities (discharge measurement) were conducted in Golarchi minor of the Left-bank area water board. The main target was to calculate real discharge at different gauge levels and to develop a rating curve and rating table for the accurate distribution of irrigation water in the command area. Hence, the discharge was measured with a current meter and the area velocity method was employed for flowing water. The discharge was taken at three different gauges i.e., 1.2ft, 1.34ft, and 1.55ft with the discharge of 51.921cusecs, 55.021cusecs, and 58.197cusecs. Then collected data was exported to MS Excel for manipulation and for developing rating curves. The power equation was developed for Golarchi minor for confirming the different discharges on different gauge heights. The results of the study calculated as 1.1ft gauge to 1.7ft gave discharge 50.383cusecs to 61.009cusecs. It is concluded that the present study suggested that there should have an automatic gauging station to know the real demand for irrigation water in the command area and di-siltation should be done.