Rod Height Research Articles

Heat transfer enhancement of a Stirling engine heating tube with three-pronged slant rods under oscillatory flow

Heaters are crucial components in Stirling engines, where the working medium adsorbed heat from an external heat source. Enhancing heat transfer within the heater is essential for boosting the operational efficiency of the Stirling engine. In this study, a tube equipped with three-pronged slant rods was employed to improve the heat transfer within the heater under conditions of oscillatory flow. Three pairs of dynamic longitudinal vortices were generated and exhibited regular movement patterns with distinct phase angles. In comparison to the smooth tube configuration, the enhanced tube outlet exhibited a notable increase in the average working-medium temperature by 62 K and 46 K during the entry and return stages, respectively. The degree of heat transfer enhancement was found to be contingent upon the pitch, height, and inclination angle of the slant rod. Optimal heat transfer enhancement was achieved with slant rods featuring a pitch of 26 mm, a height of 3.5 mm, and an inclination angle of 45°. The performance evaluation criterion ranged from 1.29 to 1.81 of enhanced tube compared to smooth tube. These findings underscore the effective enhancement of heat transfer facilitated by the three-pronged slant rods within the Stirling engine's heater.

Prediction of critical heat flux in non-uniform heated rod bundle based on modified CHF empirical correlations

The accurate estimation of critical heat flux (CHF) continues to be a significant challenge in the study of radial and axial non-uniform heated rod bundles under NHR-200Ⅱ operating conditions. The present work develops the subchannel analysis code CTF algorithm that incorporates modified CHF empirical correlations to forecast CHF of non-uniform heated rod bundles preliminarily. The article selected experimental data from HTRF, which includes both uniform heated and non-uniform heated rod bundle CHF experiments, for preliminary validation and analysis of this method. The results demonstrated that the predicted results of modified Barnett correlation have the good agreement with the experimental values. Additionally, the modified Barnett correlation is used to predict the CHF of rod bundles under various power distribution. In different radial power distribution, the critical power of rod bundles decreases with the increase of radial power factor ratio. In different axial power distribution, the critical power in inlet and outlet peak distribution is lower than uniform heated rod bundle. Regarding the case of radial uniform heating and axial inlet peak distribution, CHF locations often occur near the central section of the heated rod height. In the axial intermediate peak distribution, CHF positions often emerge in the intermediate and downstream sections of the heated rod to the outlet. In a typical operating scenario of the NHR-200II, the CHF will occur towards the exit of the hot central subchannel, particularly near the radial heated rod exhibiting the maximum thermal power. The occurrence of CHF can be attributed to factors such as lower mass flux, higher local equilibrium quality, and heat flux.

Evaluasi Pertumbuhan Klon Tanaman Tebu (Saccharum officinarum L.) Ratoon I Di Desa Watesari, Kecamatan Balongbendo, Kabupaten Sidoarjo

In the last five years, sugar cane production in Indonesia has fallen by 4%. Sugar self-sufficiency can be achieved through plant breeding programs to create high-yielding sugarcane varieties. The research objective was to determine the correlation between growth variables, genetic diversity, and sugarcane (Saccharum officinarum L.) growth in test clones. The research was conducted at the Watesari Village, Balongbendo District, Sidoarjo Regency in November 2022 - August 2023. The test materials were clones SB01 UMG NX 22, SB03 UMG NX 22, SB04 UMG NX 22, SB11 UMG NX 22, SB12 UMG NX 22, SB19 UMG NX 22, and SB20 UMG NX 22, BL variety and PS881 variety. The variables observed included stem height, stem diameter, number of stems, number of leaves, and brix. Data analysis used ANOVA, DMRT test, correlation test, genetic diversity, and heritability. The SB12 UMG NX 22 clone had the best growth, including stem height of 293.89 cm (39 MSK); total of 8.22 units (31 MSK), 8.44 units (33 MSK), 8.44 units (35 MSK), 8.78 units (37 MSK), and 9.11 units (39 MSK). There is a correlation between growth variables. There are genetic variations that affect the growth of sugarcane plants including moderate KKG values ​​(stem diameter, number of stems, and brix). Low KKG (stem height and number of leaves). Low GFC (stem height, stem diameter, stem, number of leaves and brix). H2 height (rod height, stem diameter, number of rods, and brix). Moderate H2 (number of leaves).

Research on the Comparison Properties of PDMS Specimens Demolding Processes and the Mechanical Performance of Hollow-Solid Ratios of Flexible Telescopic Rods.

The main motivation of this work was to demonstrate a hollow telescopic rod structure that could be used for minimally invasive surgery. The telescopic rods were fabricated using 3D printing technology to make mold flips. During fabrication, differences in biocompatibility, light transmission, and ultimate displacement were compared between telescopic rods fabricated via different processes, so as to select the appropriate process. To achieve these goals, flexible telescopic rod structures were designed and 3D-printed molds were fabricated using Fused Deposition Modeling (FDM) and Stereolithography (SLA) techniques. The results showed that the three molding processes had no impact on the doping of the PDMS specimens. However, the FDM molding process had lower surface flatness accuracy compared to SLA. The SLA mold flip fabrication exhibited superior surface accuracy and light transmission compared to the other methods. The sacrificial template method and the use of HTL direct demolding technique had no significant impact on cellular activity and biocompatibility, but the mechanical properties of the PDMS specimens were weakened after swelling recovery. The height and radius of the hollow rod were found to have a significant impact on the mechanical properties of the flexible hollow rod. The hyperelastic model was fitted appropriately with the mechanical test results, and the ultimate elongation increased with an increase in hollow-solid ratios under the uniform force.

Diagnosing core local flow blockages in a VVER-1000/446 reactor using ex-core detectors and neural networks

According to the Defense in Depth (DiD) concept, it is crucially important to detect and mitigate the consequences of accidents in Nuclear Power Plants (NPPs) in the early stages. Due to the nature of local blockages, the timely and suitable detection of melting accidents is a challenging task. Therefore, developing early detection and accurate mechanisms to prevent nuclear accidents as well as mitigation of their consequences are an essential step to be taken into account. In the present study, an add-on system for detecting and monitoring local melting accidents which in the early stages do not lead to SCRAM, is developed using neural networks and neutron ex-core detectors. The results of the core MCNPX model in terms of local flow blockage location in different sub-channels are used as the network training inputs. The core is divided into four, eight, and twenty-four angular segmentations, along with seven radial and ten axial partitions. More than 50,000 local blockage accidents are simulated in the MCNPX code, and 500 networks are trained for achieving an optimal network topology with 90.1% accuracy. The results of trained network shows that the proposed monitoring system is capable of diagnosing local flow blockages in less than one-tenth of a fuel rod height. The sensitivity and noise analysis results can represent the reliability of the designed system considering blockage distances from the detectors. The obtained results demonstrate that by implementing the proposed add-on system, local blockage accidents can be diagnosed with high accuracy.

Modeling consolidation of wax deposition for progressive cavity pump using computational fluid dynamics

This study aims to investigate wax deposition in progressive cavity pumps (PCP), which are widely used in the oil industry. Wax buildup on the walls during extraction can significantly impact the efficiency of the pump, with its thickness being determined by both oil properties and PCP operating conditions. Using computational fluid dynamics (CFD), a detailed analysis of the effect of different specifications, such as rod diameter, rotation speed, inlet velocity, dynamic viscosity, and rod height on wax deposition is conducted. The study also considers the impact of rotational momentum on swirl flow and includes a large-scale simulation of 3,000 cases across a wide range of conditions. Shear rate, a crucial parameter in determining wax thickness, is analyzed and modeled through regression using deep neural networks. This regression model can be used to predict wax thickness based on factors such as inlet velocities, rod diameters, viscosities, and rotation speeds. The results of these large-scale simulations and the proposed regression model will aid in understanding the relationship between operating conditions and oil properties in the context of PCP systems.

A narrow-channeled backward-facing step flow with or without a pin–fin insert: Flow in the separated region

This paper reports an experimental investigation of the separated flow region of a backward-facing step (BFS) turbulent flow. The goal was to characterize the three-dimensional flow field in a narrow BFS channel with or without a pin–fin insert. Consequently, a closed BFS channel of an expansion ratio 1.25 and aspect ratio 8.0 was tested. The pin–fin inserts employed were of 85 % porosity, and of rod height similar to the step height h. The Reynolds number of the in-coming flow based on the center-line mean streamwise velocity and h was maintained at 6000. The presence of the insert and its location behind the step were also varied from 0.69h to 15.58h. Using a planar particle image velocimetry, detailed velocity measurements were made across several spanwise planes within the entry and separated regions of the test section. The results show asymmetric qualities of reattachment length, vorticity and turbulent statistics about the spanwise plane. It is also evident that the use of inserts directly behind the step transforms the flow into one without any separated section. However, by varying the insert between 2.9h and 15.6h, the extent of the recirculation zone can be modulated between 56 % and 108 % of the length that exists without inserts. Additionally, the inserts may be used to enhance turbulent production while creating regions of energy sink. Apart from the physics unveiled in this study, the data presented provide valuable benchmark for validation, as well as suggestions to build more robust turbulent models to simulate narrow-channeled BFS flows.

Design and Evaluation of a Mechanical Floor-Standing Jujube Picker

The poor adaptability of existing harvesting machinery and low work efficiency is observed due to the low-level mechanized harvesting of Xinjiang jujube orchards. A mechanical floor-standing jujube picker was designed on the basis of the characteristics of the high fruit drop of the Xinjiang jujube harvest period. The machine can pick up the jujubes, which have been manually collected into strips on the ground. The structure and working parameters of the pickup device are determined in accordance with the pickup principle. The conditions for satisfying the picking operation were analyzed, and the range of motion speed ratio parameters to meet the pickup operation was obtained. Furthermore, the contact process of jujubes on the conveying and separating device was analyzed and studied; the factors affecting the collision damage and conveying the balance of jujubes were analyzed; and the basic structural parameters of the conveying and separating devices were determined. A mechanical floor-standing jujube picker was also fabricated for trial. A three-factor and three-level Box– Behnken test was performed by taking the forward speed of the machine, the speed of the strip brush roller shaft, and the hole pitch height of the profiling rod as factors, and the pickup, breakage, and impurity rates of jujubes as indicators. Results show that when the forward speed of the machine was 0.3 m·s−1, the speed of the strip brush roller shaft was 53 rpm and the hole pitch height of the profiling rod was 60 mm. The jujube pickup rate of the machine was 92.11%, the breakage rate was 2.07%, and the impurity rate was 4.15%. The relative error with the prediction model was less than 8%. Thus, the model is reliable and meets the operational requirements. This study can provide a reference for the mechanical floor-standing jujube picker.

Performance of lisianthus varieties in a shaded environment

Lysianthus cultivation is a recent activity when compared to the main cut flowers, and little is known about the techniques and the use of shading screens that can increase productivity in floriculture, resulting in favorable morphophysiological responses to the crop. The objective of this study was to verify whether shading screens impact the growth performance of lisianthus varieties. The experiment was carried out in a greenhouse in São Benedito farm, located in São Benedito, Ceará. The varieties studied were Lisianthus ABC 2-3 Blue, Lisianthus Allemade White and Lisianthus ABC 2-3 Rose, and three environments, one with aluminized screen (AS), one with red screen (RS) and the third environment without screen shading (WS). The experimental design was completely randomized in a 3 x 3 factorial scheme, with three environments and three varieties with three replications. The following were analyzed in cm: button diameter (BD); rod height (RH); actual size (AS); commercial size (CS); rod thickness (RT); and by counting, the number of buttons per stem (BS). The blue variety was better adapted to the conditions imposed by the AS environment, the rose variety presented the best results in the WS environment and the white variety, under the conditions of the experiment, would be unsuitable for the crop cultivation. The RS environment does not offer conditions conducive to satisfactory growth in rod size. Lysianthus cultivation is influenced by the use of shading screens.

Neplodnost i pretilost

The present study assessed the relationship between primary infertility and obesity in women of Delhi, India, independently, and in light of various demographic trait, lifestyle and reproductive variables. The present study was a part of a major project funded by the National Commission for Women of India, Government of India. The data were collected from 334 women, including 167 fertile and 167 infertile individuals. A two-part pretested modified quantitative interview schedule was used to collect data. The first part of the interview schedule included demographic traits, reproductive profile and lifestyle variables. The second part consisted of anthropometric measurements for BMI which were taken using an anthropometric rod (height) and digital weighing scale (weight). All the data were analysed through SPSS 22.0. The results revealed a higher prevalence of obesity and underweight among infertile women. There is a clear-cut indication that usual risk factors of obesity like physical inactivity, increasing age, higher age at marriage, and infertility-related biological issues seem to be promoting obesity in combination with infertility. Public health education is needed to increase awareness about the age at marriage. As physical inactivity leads to obesity among infertile women, counselling, awareness raising or improvement of lifestyle factors should be considered in the infertility treatment protocol.

Impact of cervical spinal cord injury on the relationship between the metabolism and ventilation in rats.

Cervical spinal cord injury typically results in respiratory impairments. Clinical and animal studies have demonstrated that respiratory function can spontaneously and partially recover over time after injury. However, it remains unclear whether respiratory recovery is associated with alterations in metabolism. The present study was designed to comprehensively examine ventilation and metabolism in a rat model of spinal cord injury. Adult male rats received sham (i.e., laminectomy) or unilateral mid-cervical contusion injury (height of impact rod: 6.25 or 12.5 mm). Breathing patterns and whole body metabolism (O2 consumption and CO2 production) were measured using a whole body plethysmography system conjugated with flow controllers and gas analyzer at the acute (1 day postinjury), subchronic (2 wk postinjury), and chronic (8 wk postinjury) injury stages. The results demonstrated that mid-cervical contusion caused a significant reduction in the tidal volume. Although the tidal volume of contused animals can gradually recover, it remains lower than that of uninjured animals at the chronic injury stage. Although O2 consumption and CO2 production were similar between uninjured and contused animals at the acute injury stage, these two metabolic parameters were significantly reduced in contused animals at the subchronic to chronic injury stages. Additionally, the relationships between ventilation, metabolism, and body temperature were altered by cervical spinal cord injury. These results suggest that cervical spinal cord injury causes a complicated reconfiguration of ventilation and metabolism that may enable injured animals to maintain a suitable homeostasis for adapting to the pathophysiological consequences of injury.NEW & NOTEWORTHY Ventilation and metabolism are tightly coupled to maintain appropriate energy expenditure under physiological conditions. Our findings demonstrate that cervical spinal cord injury results in the differential reduction of ventilation and metabolism at the various injury stages and leads to alterations in the relationship between ventilation and metabolism. These results from an animal model provide fundamental knowledge for understanding how cervical spinal cord injury impacts energy homeostasis.

Lightning strike probability and current simulation for simple structures and floating roof tank

Air terminations must be strategically positioned at high-risk points to prevent lightning bypass. The likelihood of a direct lightning strike to points on a building can be evaluated using the dynamic electro-geometrical model (DEGM), which considers the geometric proximity of lightning orientation points in spaces around the structure to meshed points on the structure. This study evaluates the probability of a direct strike to simple structures and the maximum lightning currents that may strike the structure. The DEGM concept is applied within a defined lightning collection volume which saves computation time. Patterns that can lead to alternatives to DEGM are identified within the percentage strike probability for different heights of two cuboid structures. Three floating roof tanks of radii 20 m, 30 m, and 40 m are analysed. Four classes of lightning protection are applied for a simple building in compliance with the International Electrotechnical Commission guidelines using different heights of air termination rods for a gable roof structure. For class I, the lightning strike interception probability of the two rods is 99.96%, 99.90% for class II, 99.72% for class III, and 99.48% for class IV. Magnitude colour-coded 3D diagrams are presented to highlight strike probability and current variations.

Experimental and numerical investigations on longitudinal vibration of suspended monorail trains induced by bogie pitching motion

The longitudinal harmonic vibrations found in the suspended monorail train (SMT) seriously affected the ride quality and dynamic behaviour. In this work, the experimental and simulated analyses are carried out to reveal the essential phenomenon, occurring mechanism and possible solutions to this issue. Firstly, the ride quality and vibration transmission of the tested SMT system are investigated. It is found that the longitudinal vibrations with the frequency of 2.7Hz occur to the carbody, bogie frame and suspension of the train system. Due to the secondary suspension is lower than the gravity center of the bogie frame, the bogie pitch motion with low damping ratio can be easily excited. The longitudinal components of the bogie pitch motion will transfer to the carbody and wheelset through traction rod and primary suspension, respectively. After that, the multibody dynamic model of a suspended monorail train is developed. Based on the numerical model, some parametric simulations, e.g. rubber stiffness, traction rod height and secondary damping, etc., are carried out to propose solutions to relieve the longitudinal vibrations. Finally, the field tests for the SMT arranging the longitudinal dampers are conducted to verify its improvement to longitudinal vibrations.

Accounting for dissipation of the energy of the supple base

AnnotationWhen calculating the foundations and structures on a compliant basis for the action of dynamic effects, the mathematical model of the base should reflect the real conditions for deformation of the base, due to their lamination, limited by the distribution property, weight and others. This is more, in our opinion, the axisymmetric columnar model of a compliant base is responsible, which takes into account the important properties of the ground base at a dynamic effect, as the extremity of the oscillation distribution zone and its inertia. In this case, the model allows us to determine not only the movement of the boundary plane, but also the stress-strain state of the base. With resonant phenomena, the accounting of energy dissipation during oscillations of the base is essential. The paper discusses the adaptation of the axisymmetric columnar model on a dissipative base, in which the dispersion of energy is carried out according to the complex hypothesis by E.S. Sorokin. The model in question is a cylindrical body in the form of a rod height H and radius R, large enough to believe that the amplitudes of displacements on the cylindrical surface of the rod are zero, when the rod on the outer end is loading within the centrally located circular area with a radius r, much smaller R. The basis, obeying the three-axis linear physical law, is in the conditions of axial symmetry, therefore, only vertical u and radial w movements are observed, which are functions of variables x, r, t. The solution of the dynamic Liame equations described by the deformation of the cylindrical body was carried out by the discrete method of L.V. Vinokurov, according to which the solution was found in an analytical form in the variable x, and in the variable r - in the finite-difference. The use of a method of separation of variables by Fourier, a system of discrete differential equations in private derivatives was reduced to a system of differential equations in ordinary derivatives, the integration of which was carried out using Euler substitutions. Permanent integration was determined from the boundary conditions at the end of the cylindrical rod. The solutions obtained show that energy dissipation accounting causes a phase shift between the perturbing load and the movement of the base and to a significant decrease in the amplitudes of oscillations in the resonance zone.

IMPROVEMENT OF ELEMENTS OF TECHNOLOGY OF GROWING MILLET IN THE CONDITIONS OF THE RIGHT BANK FOREST BANK

The height of millet rods depended more on the year of cultivation, the plants of the second year of vegetation, regardless of the studied factors provided higher linear measurements of plant height from 108.5 to 152.2 cm in comparison to plants of the first year of cultivation from 64.1 to 70.2 cm. higher linear measurements of plant height were obtained at a row spacing of 30 cm, both in plants of the first and second year of vegetation. In plants of the first year of vegetation from 65.2 to 70.2 cm, and in plants of the second year of vegetation from 123.5 to 152.2 cm. Lower linear measurements of plant height were observed for row spacing 45 cm from 64.1 to 69.4 cm in plants of the first year of vegetation and from 108.5 to 138.3 cm in plants of the second year of vegetation. In plants of millet twigs there are some differences in forming a number of stems depending on the year of vegetation, in plants of the first year of vegetation the highest number of stems was 30 cm wide between rows and varied from 405.1 to 443.3 pieces / m2. However, in the plants of the second year of the growing season, the highest number of stems was obtained with a row spacing of 45 cm and varied from 457.5 to 488.1 units / m2. Moreover, the highest number of stems was obtained in plants of millet twigs for sowing in the first decade of May - 429.8 and 442.6 pieces / m2 in the varieties Cave-in-Rock and Foresburg. The highest level of dry biomass yield was obtained for row spacing of 45 cm from 7.0 to 8.2 t / ha, and for row spacing of 30 cm from 6.7 to 7.5 t / ha. Plants of the second year of vegetation provided a higher level of dry biomass yield, which varied from 6.9 to 8.2 t / ha. Dry biomass yields were also affected by sowing dates, the highest mass of dry biomass was obtained during sowing in the first decade of May in Cave-in-Rock varieties - 5.7, and in Foresburg variety - 6.0 t / ha.

Effects of the roughness height in turbulent boundary layers over rod- and cuboid-roughened walls

Direct numerical simulations (DNSs) of spatially developing turbulent boundary layers (TBLs) over two-dimensional (2D) rod-roughened walls and three-dimensional (3D) cuboid-roughened walls are conducted to investigate the effects of the roughness height on the flow characteristics in the outer layer. The rod elements are periodically aligned along the downstream direction with a pitch of px/θin = 12, and the cuboid elements are periodically staggered with a pitch of px/θin = 12 and pz/θin = 3, where px and pz are correspondingly the streamwise and spanwise pitches of the roughness and θin is the momentum thickness at the inlet. The first surface roughness is placed 80θin downstream from the inlet, leading to a step change from a smooth to rough surface. The rod and cuboid roughness height (k) is varied in the range of 0.1 ≤ k/θin ≤ 1.8 (13 ≤ δ/k ≤ 285), respectively (δ is the boundary layer thickness), and the Reynolds number based on the momentum thickness (θ) is varied in the range of Reθ = 300 ~ 1400. For each case, the self-preservation form of the velocity-defect and the turbulent Reynolds stresses is achieved along the downstream direction. As the roughness height increases, the roughness function (ΔU+) extracted from the mean velocity profiles increases, although the velocity-defect profiles for the rough-wall cases show good agreement with the profile from the smooth-wall case. The magnitude of the Reynolds stresses in the outer layer increases with an increase of k/δ. The outer layer similarity between the flows over the rough and smooth-walls is found when δ/k ≥ 250 and 100 for the 2D rod and 3D cuboid, respectively. The continuous increase of the Reynolds stresses in the outer layer with an increase of k/δ is explained by a large population of very long structures over the rough-wall flows. Because the characteristic width of the structures increases continuously with an increase of k/δ for the rod and cuboid roughness, a wide width of the structures leads to frequent spanwise merging between adjacent structures. The active spanwise merging events with an increase of k/δ increase the streamwise coherence of the structures with the appearance of significant meandering.

Physical Properties of indium doped Cadmium sulfide thin films prepared by (SPT)

Various thin films of cadmium sulfide doped with different weight ratios (wt %) of indium (CdS: In), were prepared on glass substrates by Spray pyrolysis technique (SPT), The Microstructural, topography and optical characteristics were studied. Pure films and doped with In 1%. The results obtained revealed that the growth toward single crystalline hexagonal- cubic phases. The dominant reflection is in the direction (101) plane with a crystalline size 47.55 nm, which is calculated utilizing Scherrer equation. The increase in In to 3% tends the structure to be the poly crystalline with the existence of the prevalent reflection in the direction of (101) plane with a the crystal size of 53.89 nm. The topography measurements showed that the surfaces of the nanostructured are in the form of rods with a height of 1.99 nm and a diameter of 50-60 nm. The rod height decreased with the increasing in doping weight ratios, while the diameter of the rod increased. The optical measurements showed lower transmittance with the increasing of doping from T% 95 to T% 64. A decrease in the optical energy gap value was noticed.

Experimental investigation on wind uplift capacity of single span Z-purlins supporting standing seam roof systems

A total of 20 specimens of single-span purlin roof assemblies considering uplift wind load were tested to investigate the structural behavior of cold-formed steel Z-purlins having the tension flange fastened to standing seam roof systems. The variables of the tests include the type of standing seam roof systems, purlin thickness, purlin height and location of sag rods. Failure modes and flexural strengths of Z-purlins with and without sag rods were obtained from the tests. The test results were also compared with the flexural strengths calculated according to the Chinese code and North American specification, respectively. Furthermore, full finite element models representing the test specimens were then developed and nonlinear analysis was performed. The test results were in good agreement with the finite element analyses in terms of failure loads, failure modes and load-displacement curves.

Linear array of dual‐polarised slot‐coupled dielectric‐rod elements for wireless applications

The design of a dual-polarised series-fed microstrip array antenna for wireless applications, especially in the 5150–5750 MHz band, is delineated in this study, which consists of 12 dielectric rods, fed by circular slots. The rod height can be exploited to improve antenna gain and control its azimuth beamwidth. Using circular slot elements with a central crossing point improves port isolation and cross polarisation. The array elements are fed via two series-fed six-element arms having 25 dB Taylor distribution in each polarisation. The given arms are fed from the centre. Regarding H-polarisation, the arms are fed with a 180° phase shift to improve isolation between the ports as well as the cross polarisation. Additionally, a reflector plane is placed behind the array to suppress back-lobe radiation. A prototype of the array antenna is fabricated and measured. The return loss of the antenna is over 10 dB, varying from 5.1 to 5.8 GHz, and the isolation exceeds 30 dB over the bandwidth. The measured and simulated patterns are presented for both polarisations.

Coeficientes de uniformidade em aspersores de baixa vazão com diferentes arranjos e altura da haste

Em irrigação por aspersão, a água é precipitada de forma artificial. Nesse sistema, a eficiência de distribuição está sujeita às características do aspersor, pressão, vazão de operação, fatores externos como vento e temperatura, tipo de arranjo e a altura da haste. Diante do exposto, objetivou-se com este trabalho avaliar o Coeficiente de Uniformidade Christiansen - CUC, Coeficiente de Uniformidade de Distribuição - CUD e Coeficiente de Uniformidade Estatístico - CUE em aspersores de baixa vazão sob os arranjos quadrangular, triangular e retangular, para altura de haste de 1,50 e 2,00 m sob baixa pressão de 10 mca. O aspersor NDJ 5022 apresentou coeficientes acimas de 80% para todos os arranjos e sobreposições, sendo arranjo triangular o que apresenta melhor custo benefício de instalação.