Pressure Head Research Articles

Effect of Core Type on Zoned Earth Dams on Total Water Head and Flux

Most dams constructed worldwide are zoned earth dams with cores of different materials. However, selecting the proper core material in an earth dam will reduce seepage and increase safety. Most of the available information on dam cores was extracted from laboratory experiments. In this study, cores of different materials used in three selected zoned dams of almost the same height were assessed based on acquired field data and numerical simulation. The selected dams are in Iraq and named Haditha Dam (designed with a compound core of compacted dolomite and asphaltic diaphragm), Hemrin Dams (designed with a hard clay core) and Khasa Chai Dam (designed with a silty clay core). The total water head and water flux through the core of each dam were simulated using a two-dimensional SEEP/W model. For high and low water depths in the reservoir of Hemrin Dam, the water flux ratios were found to be 140 and 50 times greater than that of Haditha Dam. For low water depth in the reservoirs of Hemrin and Khasa Chai Dams, the flux ratio was 17. Compared with the core of the Hadith Dam, the flux through the core of the Khasa Chai Dam was found to be triple. For studied core samples, the variation in fluxes can be related to the effect of both hydraulic conductivity and geometry of the dam core. The hydraulic conductivity is affected by the core material, while the hydraulic gradient is affected by both the core material and geometry.

Analysis of pile shaft resistance embedded in unsaturated clayey soils

ABSTRACT The finite element analysis was carried out to investigate the performance of pile foundations with dimensions (0.6 × 12) m in diameter and length, respectively, which is embedded in fully and partially saturated soils within Baghdad city. The behaviour of partially saturated clay is investigated through many factors, such as the degree of saturation, water table depth, clay shear strength, negative pressure head, soil density, permeability function, volumetric water content function, and unsaturated soil modulus (H). This study examined the adhesion factor (α) in piles at different water tables, saturation degrees, and the impact of partial soil saturation on the final shaft resistance. It is concluded that the pile capacity rises as the soil becomes partially saturated due to the water table dropping at varying depths and saturation levels. The study determined that the respective degrees of saturation and reduction of the water table in the three soils significantly influenced the skin friction values caused by partial soil saturation. The shaft resistance increases quickly when the water table is dropped to 2 and 4 metres. It is discovered that when matric suction is increased to a particular value, the shaft resistance decreases.

Sex-specific growth and morphometric sexing of chicks of the Black-headed Gull (Chroicocephalus ridibundus)

In birds, sexual size dimorphism often becomes evident as early as chicks’ growth stage. A larger sex usually has an advantage in food competition among siblings. In the smaller sex, the lesser ultimate size can be compensated by faster growth or earlier fledging. As a consequence, sex differences can manifest themselves not only in body size but also in the body condition or the rate of weight gain. This phenomenon provides additional opportunities for sexing of chicks by discriminant analysis of growth parameters. Our work deals with the influence of sex on the growth of Black-headed Gull chicks. Using logistic models, we examined growth patterns of 80 males and 76 females from hatching to departure from breeding colonies during three seasons. In males, the total head length, tarsus length, and body mass were greater than those in females from the first days of life and reached large asymptotic values. Tarsus length was a better predictor of sex than head length or body mass was. The sex of chicks did not have a significant effect on global growth rates; however, compared to males, females had a lower body condition (the difference between observed and expected chick body mass) at age 8 days and gained less weight between 21 and 28 days. Using these differences, we developed a discriminant function that allowed to correctly predict the sex of 88.5% of Black-headed Gull chicks before fledging.

Physics-Based Modelling of Plate-Fin Heat Exchangers

Aluminium plate-fin heat exchangers are widely used in automotive, aerospace, and other industrial applications. Extensive research has been conducted on these coolers, yet accurate predictive tools for their thermo-hydraulic performance are still lacking, due to the wide variety of geometric parameters and working fluids involved. This work proposes an original approach based purely on physical principles and established models, combining detailed numerical models for the extended surfaces and manifolds, with global models aimed at accurately evaluating overall head losses and heat transfer rates in plate-fin heat exchangers. Extended surfaces are studied by means of computational models of unitary fin modules under fully developed flow conditions. Entrance effects are analysed through dedicated numerical models. Numerical results on extended surfaces are extended to whole heat exchangers by global models for heat transfer and head losses, based on the ε−NTU method and the Darcy–Weisbach equation, respectively. The proposed approach is presented and validated through the analysis of a case study comprising several heat exchangers featuring different geometries and working fluids. Numerically derived heat transfer rates and head losses are compared with experimental data showing maximum deviations of ±20% for most of the tested configurations, highlighting the strength of the proposed modelling methodology.

Analytical study for two-dimensional transport of organic contaminant in a polymer material-enhanced composite cutoff wall system.

Polymer material (PM) is a novel vertical barrier material, demonstrated to be effective in impeding pollutants. However, the associated transport research is limited. This study aims to develop an analytical solution for two-dimensional transport of organic contaminant in the PM-enhanced composite cutoff wall (CCW) system, where the variable substitution and Fourier transform methods are used. This analytical solution, available in various simplifications, is effectively validated via several comparisons. Following this, the analyses show that an increase in the non-uniformity of pollution source concentration distribution shortens the PM-enhanced CCW's breakthrough time (tb), while exhibits a marginal effect on the total flux at its exit. The increment of aquifer horizontal thickness prolongs the tb to some extent, whereas an increase in its hydraulic conductivity slightly reduces the tb. Additionally, the PM layer location is found to have a little effect on the PM-enhanced CCW's barrier performance. Furthermore, the equivalent performance assessment reveals that the improvement gained from increasing the PM layer thickness far surpasses that from increasing the single-layered cutoff wall thickness, and this difference may exceed 10. For a PM layer with low hydraulic conductivity, it is more suitable for engineering scenarios with the higher hydraulic head difference. Totally, the proposed analytical solution offers a valuable tool for designing the PM-enhanced CCW.

Utilizing gene expression programming strategies for estimating relative uplift pressure head at key-points beneath straight horizontal aprons

ABSTRACT Seepage flow beneath the hydraulic structures creates uplift pressure on its floor that affects the performance of these structures. Prior studies have assumed that the cutoff wall is solid, however, perfect impermeability does not occur in the real world. This investigation yields an acceptable model for computing the relative uplift pressure at key points created by a vertical cutoff wall positioned at different locations (at the upstream end, at an intermediate location, and at the downstream end) underneath hydraulic structures. A series of numerical models based on the finite element method (FEM) were developed. With the generated data, Gene Expression Programming (GEP) is used to calculate the relative uplift pressure. The GEP model yielded high values of R 2, R, KGE, and NSE, and low values of MAE, RE%, and RMSE. Additionally, diagrams that allowed better estimation of relative uplift pressure were created. The NSE and KGE indices extracted using the GEP model are in a range of 0.75 < NSE ≤ 1 and 0.7 < KGE ≤ 1 whereas the RE% for the proposed models for each of the key points is less than 7.5%.

The Optimization of the Rear Guide Vane of a Bulb Tubular Pump Based on Orthogonal Tests

Bulb tubular pumps have been widely used in hydraulic engineering because of their compact structure, easy maintenance, high adaptability, and other characteristics. In this paper, the performance optimization of the bulb tubular pump in the South-to-North water diversion project is studied, as well as the influence of the design of the rear guide vane structure on the hydraulic efficiency of the pump. This study takes a certain type of bulb tubular pump as its research object, optimizing the rear guide vane. Firstly, the accuracy of the numerical simulation method is verified using grid convergence analysis and model experimentation. The orthogonal experimental design method is used to optimize the design, and the range analysis results show that the blade wrap angle has the most significant influence on the hydraulic efficiency and head. Finally, the optimization results under a 0° impeller setting angle were verified by numerical analysis, and the hydraulic efficiency of the optimized pump was increased by 0.7%, 0.88%, and 1.1% under low flow, design flow, and high flow, respectively. By introducing entropy generation theory for inflow analysis, the reduction in energy loss in the pump is proven, thus verifying the effectiveness of the optimization. Through the optimization, the separation fluid phenomenon on the guide vane surface is improved, the vortex scale is reduced, and the flow field in the pump is improved to a certain extent.

Structural reversal of disc cupping measured in Bruch’s membrane opening-based OCT morphometry after PRESERFLO microshunt implantation for open-angle glaucoma

Background/ AimsTo analyze the longitudinal change in Bruch’s membrane opening minimal rim width (BMO-MRW) and peripapillary retinal nerve fiber layer (pRNFL) thickness using optical coherence tomography (OCT) after implantation of a PRESERFLO® microshunt for surgical glaucoma management in adult glaucoma patients.MethodsRetrospective data analysis of 59 eyes of 59 participants undergoing implantation of a PRESERFLO microshunt between 2019 and 2022 at a tertiary center for glaucoma management. Surgical management included primary temporary occlusion of the glaucoma shunt to prevent early hypotony. Pre- and post-operative OCT examinations of the optic nerve head (ONH) and intraocular pressure (IOP) were assessed. Longitudinal change in morphometric spectral domain OCT parameters of the ONH was correlated to change in IOP.ResultsBMO-MRW increased significantly between baseline (BL) and follow-up (FU) within the first three months after surgery (BL = 171.15 ± 66.80 μm; FU = 180.78 ± 70.394 μm; p = 0.034). For the same postoperative period, the mean preoperative IOP of 24.97 ± 7.22mmHg was lowered after surgery to 13.70 ± 5.09 mmHg. Eighteen months after surgery, there was no significant change in BMO-MRW compared to baseline (BL = 169.83 ± 52.69 μm; FU = 164.98 ± 55.85 μm; p = 0.271), while mean IOP was 13.08 ± 4.48 mmHg. A decrease in IOP correlated significantly with a change in BMO-MRW (r = 0.453, p < 0.05) three months after surgery. Peripapillary RNFL thickness was unchanged in follow-up after three months (p > 0.16) and significantly decreased in later follow-up (p = 0.009).ConclusionPRESERFLO® microshunt implantation with primary temporary occlusion leads to a significant transient increase in BMO-MRW. This phenomenon is also known as structural reversal of disc cupping (SRDC). The effect seems to be less pronounced and of shorter duration when compared to previous data after trabeculectomy with comparable pre- and postoperative IOP levels.

Kinematic Alterations with Changes in Putting Distance and Slope Incline in Recreational Golfers.

Golfers must modify their motor patterns when the demands of a putting task change. The objective was to compare joint angles and putter kinematics during putting at two distances and inclines. Recreational golfers (n = 14) completed putts over four conditions: 3-foot putts on flat and incline surfaces, and 7-foot putts on flat and incline surfaces. A Vicon motion capture system measured kinematic data. Joint angles, putter angles, and spatiotemporal variables were calculated. Analysis of variance compared spatiotemporal variables, and statistical parametric mapping compared angles between putts. There were faster putter head and ball velocities during longer and incline putts. The amplitude and time of backswing increased with longer putts. Longer putts resulted in increased trunk axial rotation during backswing, downswing, and follow-through, while incline putts only resulted in greater rotation during follow-through. There were minimal differences in shoulder angle. There was greater head rotation toward the hole during all putting phases for longer putts and during follow-through for incline putts. The trunk is the primary mechanism to increase putter head amplitude, and thereby velocity, when putting from longer distances. A similar strategy could be used when putting uphill. Additional work should confirm these results in highly skilled golfers.

Hydrothermal Coupling Analysis of Frozen Soil Temperature Field in Stage of Pipe Roof Freezing Method

Taking the Sanya River Mouth Channel project as a case study, this research explores the minimum brine temperature required for the pipe-jacking freezing method during staged freezing. Based on the heat transfer theory of porous media, a three-dimensional model of the actual working conditions was established using COMSOL 6.1 finite element software. By adjusting the brine cooling scheme, the development and distribution patterns of the freezing curtain under different brine temperatures were analyzed. The results indicate that as the staged freezing brine temperature increases, the thickness of the freezing curtain decreases linearly, and the closure of isotherms is inhibited. When the brine temperature is −8 °C, the thickness of the freezing curtain meets the minimum requirement and effectively achieves the freezing effect under both low and high seepage flow conditions. Additionally, seepage significantly affects the formation of the freezing curtain, causing it to shift towards the direction of seepage, with the degree of shift becoming more pronounced as the seepage velocity increases. When the seepage velocity is so high that the thickness of the freezing curtain on one side is less than 2 m, the impact of seepage on the freezing curtain can be reduced by decreasing the hydraulic head difference in the freezing area or by increasing the arrangement of freezing pipes, thereby enhancing the freezing effect.

Video Head Impulse Test in Children-A Systematic Review of Literature.

Background and Objectives: The video head impulse test is a landmark in vestibular diagnostic methods to assess the high-frequency semicircular canal system. This test is well established in the adult population with immense research since its discovery. The usefulness and feasibility of the test in children is not very well defined, as research has been limited. This systematic review investigated and analysed the existing evidence regarding the test. The objectives were to derive meaningful inferences in terms of the feasibility, implementation, and normative vestibulo-ocular reflex (VOR gain) in normal children and in children with vestibular hypofunction. Methods: Research repositories were searched with keywords, along with inclusion and exclusion criteria, to select publications that investigated the vHIT in both a normative population of children as well as in pathological cohorts. The average normal VOR gain was then calculated in all semicircular canals for both the normal and the vestibular hypofunction groups. For the case-control studies, a meta-analysis was performed to assess the heterogeneity and pooled effect sizes. Results and Discussion: The review analysed 26 articles that included six case-control studies fulfilling the study selection criteria, out of more than 6000 articles that have been published on the vHIT. The described technique suggested 10-15 head impulses at 100-200°/s head velocity and 10-20° displacement fixating on a wall target 1 to 1.5 m away. The average VOR gain in the lateral semicircular canals combining all studies was 0.96 +/- 0.07; in anterior semicircular canals, it was 0.89 +/- 0.13, and for posterior semicircular canals, it was 0.9 +/- 0.12. The normal VOR gains measured with individual equipment (ICS Impulse, EyeSeeCam and Synapsys) in the lateral semicircular canals were largely similar (p > 0.05 when ICS Impulse and EyeSeeCam were compared). The pooled effect size in the control group was 1, and the heterogeneity was high. It was also observed that implementing the test is different from that in adults and requires considerable practice with children, factoring in the issue of peripheral and central vestibular maturation. Special considerations were suggested in terms of the pupillary calibration, goggle fitting, and slippage and play techniques. Conclusions: The vHIT as a diagnostic test is possible in children with important caveats, practice, and knowledge regarding a developing vestibular system. It yields significantly meaningful inferences about high-frequency semicircular canal function in children. Adult norms should not be extrapolated in children, as the VOR gain is different in children.

Comparative Analysis of Friction Coefficient Evolution in Hydroelectric Dam Penstocks: Theoretical vs. Numerical Methods

The objective of this study was to investigate the evolution of the friction coefficient throughout a full penstock using two different approaches. Two approaches were considered in order to assess their effectiveness in predicting head loss. A theoretical approach that based on direct determination using the commonly used Colebrook-While formula. A graphical approach that based on numerical modeling of the structure under study using Gambit 2.2 software. For the theoretical approach, the results show that whatever the other parameters set out in the Colebrook-White formula (Reynolds number, diameter and absolute roughness), only absolute roughness has a visible impact on the result obtained. For the numerical approach, the results obtained show that the friction coefficient is neither identical on the same wall, nor identical in the same portion. Nor is it identical in the same section of the pipe, as shown by the theoretical approach. This shows that head loss in a section of pipe can change over time.

Equations and characteristics of the local water head loss for fluid flow at fracture intersections

For fluid flow in fracture networks, the local water head loss will occur due to the fluid convergence or deflection at fracture intersections, which obviously affect the flow characteristics of fracture networks. In this study, equations of local water head losses for fluid flow at the fracture intersections were derived based on the work-energy principle. Then, the nonuniform flow characteristics at fracture intersections were analyzed by numerical simulations and the influences of flow characteristics including flow velocities, flow rate distributions and flow patterns in fracture intersections on local water head losses were studied. Finally, the influence of local head losses at intersections on total head losses in fracture networks was analyzed quantitatively. Through this study, a unified relationship between the local water head loss influence index Th and Reynolds number (Re) was found, by defining the influence index Th as the ratio of the normalized equivalent fracture length for the local head loss to the fracture aperture. For fluid flow in fracture networks with larger fracture apertures, smaller fracture spacing, or higher flow velocity, the influence of local head loss at the fracture intersection will be more significant. This study is beneficial for explicitly describing the local head losses at fracture intersections and quantitatively analyzing the influence of local head losses on the total head losses in fracture networks.

Potential of clay‐rich waste and industrial by‐products as effective inorganic soil amendments to enhance soil physical properties

AbstractClay minerals play a crucial role in regulating the structure and functions of soils because of their chemical nature and their interactions with other soil constituents. In this context, a key objective of the research described in this article was to assess the extent to which the addition of various types of recycled clay‐rich materials to soils prone to crusting and erosion increase their clay content and improve their physical properties. Excavated soil (ExS), considered waste under European Union law, and quarry sludge (QS), an industrial by‐product of the washing process in mining operations, were used as soil amendments. ExS is dominated by swelling clay mineralogy such as interstratified illite‐smectite, whereas QS contains high level of non‐swelling clay minerals such as kaolinite and illite, and a low level of interstratified illite‐smectite. Lysimeters were filled with topsoil (0–30 cm) from an agricultural field. Treatments where the soil was amended with these materials were compared with a control without amendment. Lettuce was cultivated for three growing seasons. After 250‐days, the aggregate stability and water retention of the topsoil were measured. The equivalent pore‐size distribution (PSD), derived from the soil water retention curve, was analysed to predict soil water and aeration status. The application of QS to the topsoil enhanced soil structure without compromising lettuce productivity compared with the control and other treatments. However, amending topsoil with ExS decreased the stability because of the abundance of swelling clay minerals. Soil water retention at saturation increased from 27% in the control to 42% and 36% with ExS and QS amendments, respectively. At a pressure head &gt;15,000 cm (residual pores &lt;0.2 μm), water retention rose from 6% in the control to 19% with ExS and 14% with QS. The application of the clay‐rich material increased small pores compared with larger ones. This led to a minor increase in porosity responsible for water movement, aeration and root growth. This observation highlights the limitations of clay application benefits, which depend on the quantity and mineralogy of the clay and the presence of other binding agents. Further research is needed to investigate the combined effects of organic matter and clay‐rich materials on improving the soil structure and optimizing the pore size distribution for multiple functions.

How Rilling and Biochar Addition Affect Hydraulic Properties of a Clay‐Loam Soil

ABSTRACTRill erosion is a significant problem worldwide as it determines relevant amounts of soil loss on hillslopes. Although, in the last few years, many studies have focused on rill erosion and biochar as soil amendment, their influence on soil hydrological properties and relevance on soil conservation strategies is still uncertain. In this paper, the effects of rill formation and biochar addition on the physical and hydraulic properties of a clay‐loam soil were assessed by laboratory measurements (water retention, hydraulic conductivity, minidisk infiltrometer data and 1H Nuclear Magnetic Resonance (NMR) relaxometry with the fast field cycling (FFC) setup) and field tests (rill formation tests at the plot scale). The rilled and non‐rilled soils did not show any difference in the volume of pores with a diameter (d) &gt; 300 μm, but the former showed a smaller volume for the pores in the size range between 300 and 0.2 μm. As compared with an untreated rilled soil, the addition of 5% (w w−1) biochar in the soil in which the rill is incised did not change the volume of pores with d &gt; 300 μm, while there were more pores of both 30 ≤ d ≤ 300 μm and 0.2 ≤ d ≤ 30 μm. Moreover, there were less pores with d &lt; 0.2 μm. Shaping the rill did not influence the hydraulic conductivity of the nearly saturated soil (pressure head, h = −1 cm), while it determined a significant decrease of the soil ability to transmit water in more unsaturated conditions (h ≤ −3 cm). The addition of biochar to the soil improved, in general, the soil aptitude to transmit water, regardless of the pore size. However, this improvement was statistically irrelevant in the case of a transport process governed by larger pores. The hydrological measurements also demonstrated that the addition of a large amount of biochar (5%) impedes soil characteristics alteration as the changes due to rilling are balanced by adding biochar in the soil. NMR was also used to measure the structural and functional connectivity of the original soil, the biochar and a mixture with three biochar concentrations (i.e., BC = 1%, 3% and 5% w w−1) traditionally applied in agronomical activity. These measurements revealed that the mixture of soil and biochar was characterised by longitudinal relaxation time (T1) values, which are related to pore sizes, longer than those measured for the soil. In addition, the soil empirical cumulative frequency distribution of T1 was always skewed towards shorter T1 values, thereby suggesting that the macro‐pore component (i.e., the largest T1 values) was never dominant while biochar addition increased the size of mesopores and micropores. Biochar concentrations larger than 3% (w w−1) did not produce appreciable changes in the pore distribution inside the mixture. The biochar component improved the structural connectivity up to BC = 5%, while decreased the functional connectivity up to BC = 3%. A relationship between the water volume contained in soil pores and the NMR data were established for the micropores (d ≤ 0.2 μm). The biochar‐amended soil was characterised by fewer small pores, but these micropores were greater than those in non‐treated soil.

Ensemble modeling of the two-dimensional stochastic confined groundwater flow through the evolution of the hydraulic head’s probability density function

Ensemble modeling of the two-dimensional stochastic confined groundwater flow through the evolution of the hydraulic head’s probability density function

Analysis and Optimization of Hydraulic Calibration for Maximum Performance of Wastewater Treatment Plants

The hydraulic calibration of treatment units in wastewater treatment plants is a crucial task. It involves demonstrating the relative placement of these various units in relation to the water line that traverses the plant, and helps indicate the ground surface for establishing the optimal elevations of the plant's structures and hydraulic controls. This process is meticulous, complex, and prone to errors. Special attention must be given to the issue of varying hydraulic loads that the plant will receive, particularly at the inlet. Such variations can disrupt hydraulic operation and negatively impact the plant's performance. For these reasons, the hydraulic calibration of treatment units must always be verified and analyzed for most of the common hydraulic constraints encountered in practice. This article focuses on the different types of flow and their regimes commonly found in wastewater treatment plants, and aims to guide users on how to optimize the hydraulic profile. It highlights the impact of head losses and integrates a range of potential alternatives for achieving hydraulic efficiency in a wastewater treatment plant.

Develop the Precise Vacuum Seeder for Nursery Plug Tray Sowing by Using the Vacuum Cleaner

The manual sowing of vegetable seeds is the general practice of vegetable nurseries in Thailand. It is the slow and labour-intensive process that causes the low production capacity. This study aims to design and develop a vegetable seed sowing machine for 200-cell plug tray plantings to substitute human labor. The prototype utilizes the vacuum cleaner to develop the suction head pressure that simultaneously offers the 200 seeds-planting per tray. The vacuum seeder mechanism is composed of the suction head unit and seeds tray unit. The prototype is operated and controlled by the automation system for continuous planting. Cantonese vegetable seed is selected to evaluate the planting precision of the prototype. Based on the design parameters obtained in laboratory experiments, the optimal condition for planting the Cantonese vegetable seeds in the 200-cell plug tray is verified by adjusting two parameters the suction pressures and the nozzle implement type. On the other hand, the planting precision is indicated by the single seed sowing index. The results showed that the average quality of feed index is 70.53% when utilizing the large nozzle implement type with a vacuum pressure of 1019 Pa. The average working cycle time per tray and the machine capacity per hour are 51.0 seconds and 70 trays, respectively. Moreover, the prototype machine costs about 43% of the average cost of the existing commercial seeders in terms of cost-effectiveness.

Principal component and cluster analysis in grain appearance, milling and cooking quality traits in rice (Oryza sativa L.)

Rice grain quality characteristics such as grain appearance, milling, cooking, and eating parameters are quite complex phenotypic attributes. The rice grain quality is governed principally by the genetic makeup of the rice variety, the biochemical composition of rice grain, and the bio-physical environment where it is produced or grown. In addition to this grain quality is also affected by the moisture conditions of rice gains at the time of processing, the equipment by which rice is processed to a finished product, and to some extent how the product is stored. It is necessary to improve grain quality traits in rice to meet the consumers' demand for premium quality rice, reduce loss at the time of milling, increase production efficiency by increasing total head rice yield, and give more profit to producers and traders of the rice supply chain. This investigation aimed to evaluate the extent of diversity present in the population comprising one hundred-five genotypes for fifteen-grain quality attributes through principal component analysis and cluster analysis. The principal component analysis identified five principal components, (PCs) accounting for 73.10% of the sum total of variations perceived between the rice genotypes of the population. From the biplot analysis of PC1 and PC2, as the two axes of a 2-dimensional coordinate plain, it was found that the grain quality traits, kernel L/B ratio, water uptake, gel consistency, head rice recovery, kernel length after cooking, thousand-grain weight, milling percentage, and kernel length have a greater contribution to the total diversity of the rice population. By using UPGMA cluster analysis, all 105 genotypes of the population were classified into five discrete groups or clusters. The observed inter-cluster distance was largest between the clusters of cluster I and cluster III (149.22), the next largest inter-cluster distance was between cluster II and cluster IV (128.35), and that of cluster III and cluster IV was (109.61) which indicated significant genetic divergence among the genotypes. A larger inter-cluster distance between the clusters suggests the possibility of harnessing heterosis for the quality traits under study as they possess higher mean values for quality attributes with corresponding greater diversity.

Modeling and Simulation of Reel Motion in a Foxtail Millet Combine Harvester

Due to the high plant height, heavy ear, and easy forward tilt of millet during harvesting, the reel of a traditional combine harvester is often difficult to adapt to the special growth characteristics of millet, resulting in serious grain loss. Therefore, optimizing the design of the reel is important to improve the harvesting efficiency of millet and reduce the grain header loss. In order to determine the optimal reel speed ratio(λ), kinematics simulation experiments and analysis were carried out under different combinations of forward speed and reel revolution speed. The results showed that the supporting effect of the reel is insufficient when λ ≤ 1, and the trochoidal trajectory of the reel can provide a backward driving force when λ &gt; 1, the optimum speed ratio of the reel should be controlled between 1.5 and 1.6. Field experiments results showed that the grain header loss rate was the lowest (0.9%) when λ = 1.6. This study provides key guidance for the adjustment of the combine harvester, effectively reducing the grain header loss rate in harvesting millet, and improving the harvesting efficiency.