Rotation Parameters Research Articles

Numerical investigations of nonlinear Maxwell fluid flow in the presence of non-Fourier heat flux theory: Keller box-based simulations

<abstract> <p>We investigate the thermal flow of Maxwell fluid in a rotating frame using a numerical approach. The fluid has been considered a temperature-dependent thermal conductivity. A non-Fourier heat flux term that accurately reflects the effects of thermal relaxation is incorporated into the model that is used to simulate the heat transfer process. In order to simplify the governing system of partial differential equations, boundary layer approximations are used. These approximations are then transformed into forms that are self-similar with the help of similarity transformations. The mathematical model includes notable quantities such as the rotation parameter $ \lambda $, Deborah number $ \beta $, Prandtl number <italic>Pr</italic>, parameter $ ϵ $ and the dimensionless thermal relaxation times $ \gamma $. These are approximately uniformly convergent. The Keller box method is used to find approximate solutions to ODEs. We observed due to the addition of elastic factors, the hydrodynamic boundary layer gets thinner. The thickness of the boundary layer can be reduced with the use of the k rotation parameter as well. When <italic>Pr</italic> increases, the wall slope of the temperature increases as well and approaches zero, which is an indication that <italic>Pr</italic> is decreasing. In addition, a comparison of the Cattaneo-Christov (CC) and Fourier models are provided and discussed.</p> </abstract>

Bistatic SAR Maritime Ship Target 3-D Image Reconstruction Method Without Distortion in Local Cartesian Coordinate

Bistatic synthetic aperture radar (BiSAR) has been attracting worldwide attention because of its forward-looking imaging and high anti-interference. In harsh environment, it is vital for BiSAR to conduct extensive surveillance, imaging, and recognition of maritime ship targets. However, under the disturbance of sea waves, the ship target has an unknown and massive three-dimensional (3-D) rotation, so that its imaging projection plane (IPP) is also undetermined. Thus, high-dimensional random distortion appears in imaging results, making it difficult to recognize the target through two-dimensional distorted images effectively. To solve these problems, bistatic SAR maritime ship target 3-D image reconstruction method without distortion in local Cartesian coordinate (LCC) is proposed. In this paper, according to positions of scatterers and rotation parameters, significant differences of different scatterers of maritime ship targets have been found in bistatic range, Doppler centroid (DC), and Doppler frequency rate (DFR), which lays a solid foundation for the scatterer separation of ship targets. On this basis, a 3-D R-DC-DFR domain is constructed, and 2-D echoes of the maritime ship target are projected into R-DC-DFR domain to separate scatterers. Then, by remapping data of transmitter and receiver in R-DC-DFR domain to LCC, as well as evaluating their similarity metric, the optimal rotation parameters of the ship target can be obtained via the maximal similarity. Therefore, the image distortion caused by the unknown IPP has been removed, and 3-D image reconstruction of ship targets can be realized without distortion in the LCC. Furthermore, to evaluate performances of 3-D image reconstruction for different rotation parameters and bistatic configurations, 3-D reconstruction index is proposed and analyzed. Both point-targets and maritime ship targets are simulated to emphasize the effectiveness of the proposed method.

Entropy analysis of hybrid nanofluid flow over a rotating porous disk: A multivariate analysis

The major focus of this work is on the flow of a time-dependent biviscosity hybrid nanofluid boundary layer across a rotational permeable disk with the consideration of the applied external effects of magnetic field and thermal radiation. This study also investigates the transfer of heat flow both subjectively and quantitatively. In the classic Von Karman issue, nanofluids comprising nanoparticle volume fractions of Ag-MgO/60% water and 40% ethylene glycol nanofluid are considered instead of Newtonian regular fluids. The governing equations are transformed into a system of nonlinear ordinary differential equations using Von Karman transformations. The equation for the generation of entropy is calculated as a function of velocity and temperature gradient. This equation has been made non-dimensional by adding geometric and physical flow field-dependent parameters. The velocity profiles in the radial, tangential, and axial directions, as well as the axial pressure gradient, nanoparticle temperature distribution, local skin friction, Nusselt number, and Bejan number, are calculated by using MATLAB bvp4c. The concept of multivariate analysis is executed in the numerical results of the Nusselt number, which is helpful to indemnify the behavior of the rate of heat transfer in the disk. Additionally, a rotation parameter is generated by the spinning phenomena, which regulates the disk's movement. Increasing the rotation of the disk causes fluid velocity to accelerate in both the radial and cross-radial directions, while contrasting phenomena can be noticed in the axial velocity of the flow. Entropy generation in a system is measured by the Bejan number. It has a significant infl

Моделювання витрат та вимірювання електричної енергії електродвигунів

The activity of determining the energy efficiency of electric motors includes several stages of work. These include modeling the operation of engines with the help of specialized software products, which allows you to determine the necessary parameters of electrical energy consumption, load, and rotational parameters in various operating modes. However, the most effective way is to obtain the real operating characteristics of the electric motor on test stands. This is due to many factors, from mechanical malfunctions to inconsistencies in the technical characteristics declared by the manufacturer. At the same time, both for the first and other methods, the problem lies in the optimization of the measuring equipment, which requires reducing the error, increasing the speed and sensitivity of the measuring transducers. The parameters that require special attention include the consumption of electrical energy, which in certain areas of industry is decisive during the design of technological sites, determination of industrial policy, production volumes, etc. This article proposes a way to establish the relationship between these parameters, the practical value of which, in different operating modes of the electric motor, will make it possible to evaluate both the economic efficiency of the electric machine and the possible risks associated with safe further operation, the period of operation and the ability to create the necessary acceleration moments at given loads.

Parameter Extraction of Accelerated Motion Targets Based on Vortex Electromagnetic Wave Radar

Vortex electromagnetic (EM) wave radar can obtain more accurate rotation parameters for target classification and recognition. However, the existing rotation parameter extraction methods are difficult to obtain the acceleration and initial phase of composite moving target in the case of multiple scattering points. In this paper, the estimation error of accelerated motion target features in a situation with numerous scattering points is examined for the first time, along with a method for extracting accelerated motion target parameters based on vortex electromagnetic wave radar. Firstly, the relationship between the characteristics of non derivable points (NDPs) in the rotating Doppler frequency shift and the characteristics of the target’s spin motion is analyzed, the method of estimating the number of scattering points is studied, and the formula for extracting the spin parameters is derived. After that, the time-frequency analysis of the echo signal is combined to extract the target translational motion characteristics. Simulation results show that the proposed method is effective.

ENTROPY ANALYSIS OF HYBRID NANOFLUID FLOW OVER A ROTATING POROUS DISK: A MULTIVARIATE ANALYSIS

This article discusses the flow of a time-dependent biviscosity hybrid nanofluid boundary layer across a rotational permeable disk with effects of magnetic field and thermal radiation, and the subjective and quantitative transfer of heat flow. In the classic Von Karman issue, nanofluids comprising volume fractions of Ag-MgO/60% water and 40% ethylene glycol are considered instead of Newtonian regular fluids. The governing equations are transformed nonlinear ordinary differential equations using Von Karman transformations. The equation for the generation of entropy is calculated as a function of velocity and temperature gradient. This equation is made nondimensional by adding geometric and physical flow field-dependent parameters. The velocity profiles in the radial, tangential, and axial directions, as well as the axial pressure gradient, nanoparticle temperature distribution, local skin friction, Nusselt number, and Bejan number, are calculated by using MATLAB bvp4c. The multivariate analysis is implemented in the numerical results of the Nusselt number. A rotation parameter is generated by the spinning phenomena, which regulates the disk's movement. Increasing the rotation of the disk causes fluid velocity to accelerate in both the radial and cross-radial directions, while contrasting phenomena can be noticed in the axial velocity of the flow. The temperature and wall shear stress of a nanofluid both rise with the disc's Brinkman number and the volume fraction of nanoparticles. Increasing the thickness of the thermal boundary layer raises the axial pressure gradient. Entropy measured by the Bejan number Influences the magnetic field and the Biot number. Physical parameters presented in this article may be used to optimize the system's performance. A magnetic rotating porous disk drives could be used in nuclear space propulsion engines and in heat transfer augmentation in thermal management and renewable energy sources.

High resolution spectroscopy of asymmetric top molecules in nonsinglet electronic states: the ν3 fundamental of chlorine dioxide (16O35Cl16O) free radical in the X2B1 electronic ground state.

Highly resolved spectra of the 16O35Cl16O isotopologue of chlorine dioxide were recorded with a Bruker IFS 125HR Fourier transform infrared spectrometer in the region of the ν3 band. The analysis was made in the frame of the spin-rotational effective Hamiltonian (in A-reduction and Ir-representation) taking into account spin-rotational coupling operators up to the sixth order and the corresponding reduction of the Hamiltonian. The mathematical description of the ro-vibrational spectra was implemented to the specially created computer program ROVDES. Under the present experimental conditions, we were able to assign more than 5200 spin-rotational transitions to the ν3 band. This number is 2.4 times higher compared to the previous studies available from the literature. The vibrational ground state parameters were improved, and the 2220 upper spin-rotation-vibration energy levels were determined and used as initial data in the inverse spectroscopic problem with the derived effective spin-rotational Hamiltonian. A total of 37 fitted parameters were determined (22 rotational and centrifugal parameters and 15 parameters of spin-rotation coupling). The appearance of strong Coriolis resonance interactions between the (001) and (100) vibrational states in the sets of (001)[N,Ka = 9], (001)[N,Ka = 17], (001)[N,Ka = 18] and (001)[N,Ka = 19] spin-rotation-vibration levels was experimentally observed for the first time and explained. The drms = 1.4 × 10-4 cm-1 reproduction of the initial "experimental" upper ro-vibrational energy values was achieved which is considerably better compared to the use of parameters from a previous study ([J. Ortigoso et al., J. Mol. Spectrosc., 1992, 155, 25-43]).

Optimization of Sustainable Process Parameters of Friction-Stir Welding of Aluminium Alloy by Taguchi Method

In the current paper, AA6101-T6 aluminium alloy was subjected to friction stir welding (FSW) utilizing a vertical milling machine. Alloy plates were welded in butt position to provide a virtually flat interface, using a tool shape that was carefully selected. Because of the excessive generation of heat via the tool and workpieces during friction stir welding, substantial deformation in the nugget zone is seen. The mechanical attributes of the base metal at the joint are significantly impacted by an excessive variation in temperature at the weld. In this experiment, mechanical properties-related changes through the FSW process are kept to a minimum to achieve high tensile strength. The tool’s rotating speed (measured in rpm), the workpieces' traverse speed (measured in mm/min), and the tool tilt angle were chosen as the parameters to regulate the weld quality. As a result of its 44% contribution, the rotating speed parameter is shown to be the most beneficial one for stir welding. The metric determining transverse speed contributes the least, at 19%. For effective stir welding, such as high strength welds, defect-free welds, short welding times, low welding costs, etc., it is preferred that the tool rotational speed parameter be concentrated. By using sustainable Taguchi approach to optimize the chosen process parameter, high tensile strength is achieved at the welded connection.

Анализ технологической и кинематической возможностей формообразования упорной резьбы фрезой общего положения

The paper proposes new kinematic methods in shaping external and internal buttress thread by milling with a single-disk tool according to the scheme with crossing axes of the thread and the general position tool using two angles of its rotation. The range of the thrust threads standard sizes was established, which implied technological possibility of milling using the proposed kinematic methods with one tool standard size. Accuracy of the buttress thread according to GOST 10177-82 was studied on the basis of geometric simulation of shaping kinematics, and values of the maximum geometric error and the error in the average diameter were determined depending on the tool rotation angles and geometric parameters. For the accepted standard sizes of the buttress threads, values of rotation angles of the thread cutter rotation axis and parameters of its working part were found, which makes it possible to shape the thread with a degree of accuracy corresponding to GOST 25096–82.

Hall and Ion Slip Impacts on Unsteady MHD Convective Flow of Ag-TiO2/WEG Hybrid Nanofluid in a Rotating Frame

Background: The radiative magnetohydrodynamic (MHD) flow of an incompressible viscous electrically conducting hybrid nanofluid over an exponentially accelerated vertical surface under the influence of slip velocity in a rotating frame taking Hall and ion slip impacts is discussed. Methods: Water and ethylene glycol mixture have been considered as a base fluid. A steady homogeneous magnetic field is applied under the assumption of a low magnetic Reynolds number. The ramped temperature and time-varying concentration at the surface are taken into consideration. The first-order consistent chemical reaction and heat absorption are also regarded. Silver (Ag) and titania (TiO2) nanoparticles are disseminated in base fluid water and ethylene glycol mixture to be formed a hybrid nanofluid. The Laplace transformation technique is employed on the non-dimensional governing equations for the closed form solutions. Results: The phrases for non-dimensional shear stresses, rates of heat, and mass transfer are also evaluated. The graphical representations are presented to scrutinize the effects of physical parameters on the significantflow characteristics. The computational values of the shear stresses, rates of heat and mass transports near the surface are tabulated by a range of implanted parameters. Conclusion: The resultant velocity grows by an increase in thermal and concentration buoyancy forces, Hall and ion-slip parameters, whereas rotation and slip parameters have overturn outcome on them. The temperature of hybrid Ag-TiO2/WEG nanofluid is relatively superior to that of Ag-WEG nanofluid. Species concentration of hybrid Ag-TiO2/WEG nanofluid decreases due to an increase in Schmidt number and chemical reaction parameter.

ROTATING CASSON NANOFLUID CONVECTION FOR Au, Ag, CuO, AND Al2O3 NANOPARTICLES EMBEDDED BY DARCY-BRINKMAN POROUS MEDIUM

The present paper investigates convection in a Casson nanofluid layer in porous medium under the influence of Coriolis force using Darcy-Brinkman model. The analysis is carried out using linear stability theory, normal mode technique, and one term Galerkin type weighted residual method for various metallic and non-metallic nanoparticles. The outcomes are compared with previously published results, and fine agreements are noted for the permissible range of parameters. Numerical simulation for porous media is carried out for blood (Casson fluid) using the software Mathematica to make the investigation helpful for practical applications. The effect of porous medium, rotation, Casson parameter, and nanoparticle parameters is discussed. Interestingly, it is found that though Casson fluids are more stable as compared to regular fluids, the Casson parameter itself has a destabilizing effect on the system. The main objective of the study is to consider the impact of Coriolis force on a Casson nanofluid layer with metallic and non-metallic nanoparticles. This effect is of paramount importance in geophysical studies, particularly in the extraction of crude oils. Further, by increasing the rotation parameter, the axial velocity of the blood-based Casson fluid increases, which may help in the treatment of stenosis of arteries and throat. The importance and novelty of the study is the fact that Coriolis force can stabilize various nanoparticle-based Casson fluid layer systems, which were otherwise unstable. As far as metallic and non-metallic nanoparticles are concerned, the stability pattern followed by metallic nanofluids is iron-blood > copper-blood > silver-blood > gold-blood, and for non-metallic nanofluids is silica-blood > alumina-blood > titanium oxide-blood > copper oxide-blood.

SOLAR ENERGY ENCOURAGEMENT IN SOLAR HVAC USING EYRING-POWELL TERNARY-HYBRID NANOFLUID FLOW IN POROUS MEDIUM WITH CATTANEO-CHRISTOV HEAT AND MASS FLUXES

This study presents a new 3D mathematical model to analyze rotating Eyring-Powell ternary-hybrid nanofluid flow in solar HVAC systems. The study examines the flow of a mixture of tri-hybrid nanoparticles inserted into ethyl glycol over a stretching sheet through a porous medium. The model considers solar thermal radiation, activation energy impact, and boundary qualifications. Similarity variables are used to transform governing equations into a set of nonlinear coupled ordinary differential equations, which are solved numerically using the Runge-Kutta-Fehlberg approach in MAPLE 2022 software. The results are shown graphically to investigate the impacts of regulating parameters on skin friction, heat, and mass transfer. It is demonstrated that an increase in the Eyring-Powell fluid and rotation parameters increases radial skin friction. Furthermore, the temperature slip and relaxation time parameters tend to reduce the Nusselt number, while the radiation parameter boosts the Nusselt number. The use of ternary nanofluids results in the highest Nusselt numbers. The study has importance in engineering applications such as the dying of metals and extrusion processing.

Combination strategy for consistent final, rapid and predicted Earth rotation parameters

The accurate knowledge of the Earth’s orientation and rotation in space is essential for a broad variety of scientific and societal applications. Among others, these include global positioning, near-Earth and deep-space navigation, the realisation of precise reference and time systems as well as studies of geodynamics and global change phenomena. In this paper, we present a refined strategy for processing and combining Very Long Baseline Interferometry (VLBI), Satellite Laser Ranging (SLR), Global Navigation Satellite Systems (GNSS), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS) observations at the normal equation level and formulate recommendations for a consistent processing of the space-geodetic input data. Based on the developed strategy, we determine final and rapid Earth rotation parameter (ERP) solutions with low latency that also serve as the basis for a subsequent prediction of ERPs involving effective angular momentum data. Realising final ERPs on an accuracy level comparable to the final ERP benchmark solutions IERS 14C04 and JPL COMB2018, our strategy allows to enhance the consistency between final, rapid and predicted ERPs in terms of RMS differences by up to 50% compared to existing solutions. The findings of the study thus support the ambitious goals of the Global Geodetic Observing System (GGOS) in providing highly accurate and consistent time series of geodetic parameters for science and applications.

ОЦІНЮВАННЯ НЕВИЗНАЧЕНОСТІ ВИМІРЮВАННЯ ОБЕРТАЛЬНИХ МОМЕНТІВ ЕЛЕКТРОДВИГУНІВ НА БАЗІ ТЕОРІЇ НЕЧІТКИХ МНОЖИН

The use of the theory of fuzzy variables in metrology opens up new opportunities for taking into account informal information about the sources of uncertainty in the measurement of various mechanical quantities. This is especially relevant when determining errors in the rotational parameters of electric motors. This article discusses a new approach to measurement accuracy assessment that goes beyond traditional measurement methods. In particular, attention is focused on the task of assessing the reliability range of measurements of rotational parameters of electric motors within a certain accuracy class. Each measurement is accompanied by an error that has both systematic and random components. Since the exact value of the measurement results cannot be known within the range that is limited by the accuracy class of the device, the article proposes to consider the true value of the measured value as a fuzzy variable, which allowed getting a better idea of the uncertainty of the measurement. In the article, an attempt was made to estimate the approximate accuracy of measurements of rotational parameters of electric motors using a specially developed membership function. The practical application of this method makes it possible to assess the reliability of measurements in different modes of operation of electrode benders. For a more detailed analysis of this problem, the article provides examples of solving similar problems using the theory of possibilities and the theory of fuzzy sets, which made it possible to better take into account the uncertainties of the rotational parameters of electric motors and determine further ways of developing this problem.

Numerical treatment of squeezed MHD Jeffrey fluid flow with Cattaneo Chrisstov heat flux in a rotating frame using Levnberg-Marquard method

The present communication examines the unsteady-two-dimensional (2-D) squeezing flow of magnetohydrodynamic (MHD) Jeffrey fluid between two parallel plates (HT2DUSMHDJF). In its own plane, the bottom channel plate is extended while the upper plate squeezes towards the lower plate. The complete structure is takan is a rotating frame. Cattaneo-Christov heat flux model (CCHFM) is forced to explore the features of heat transfer. Distinct the conventional position, Instead of the Fourier heat conduction law, the heat flux is implemented by the Cattaneo-Christov theory. The resultant systems are computed through Artificial Neural Network (ANN). The behaviors of a number of relevant parameters are analyzed through graphs and numerical data. The velocity profile increases for Deborah number β and squeezing parameter sq and decreases for rotation, magnetic and relaxation time parameter ω, M, and λ1 respectively. Also the Skin friction coefficient decreases for λ1 and Sq and increases for high value of Deborah numbers β, ω and M.

Aerodynamic Analysis of Propeller for Heavy Lifting Drone Applications Using Blade Element Momentum Analysis

Nowadays, drone technology is seen to be rapidly advancing in various fields and applications including photography, military, transportation, sports, and many more. Therefore, each drone designs require different aerodynamic requirements, which includes different types of propeller designs. By revolving and generating airflow, the propellers give drones or unmanned aerial vehicles (UAV) a lift force or thrust. This work examines the method to calculate the thrust force generated by propellers using the Blade Element Momentum Analysis which is programmed in MATLAB. This program is developed to perform the calculation of thrust and torque for a given propeller blade geometry. This investigation compares the thrust coefficient produced by different propeller designs a various rotation speeds and parameters using the extended blade element momentum theory. Five different types of propellers are analysed and simulated using the in-house MATLAB program. The effects of rotational speeds are then added to these databases. At low advance ratios compared to a generic blade element-momentum model, a considerable improvement in modelling accuracy is seen when results are compared to experimental ones. The calculation may overestimate performance by 5% to 10%.

ALGORITHM FOR DETERMINING THE TORQUE OF ELECTRIC MOTORS USING INDIRECT MEASUREMENT METHODS

Indirect torque measurement methods can be performed in a variety of ways, depending on the specific situation and available tools. One such way is to measure the displacement, or speed of rotation of the shaft and use this information to calculate the moment using the moment of inertia equation. For this, it is necessary to know the moment of inertia and the angular acceleration, which can be measured using a gyroscope or accelerometer. Another way is to measure the voltage and current in the electrical circuit connecting the motor and the power source by determining the power of the electric motor. However, indirect methods of measuring torques of electric motors are based on the measurement of other physical parameters that correlate with torque, such as current, voltage, rotation frequency, etc. These methods are often used because of their cost-effectiveness and ease of implementation, but they have some drawbacks. In particular: indirect methods are usually less accurate than direct methods because they depend on mathematical models and correlations between different parameters, which may be imprecise or incomplete; parameters that are measured by indirect methods may be influenced by external factors, which may affect the accuracy of measurements; calibration of devices is usually carried out in laboratory conditions, so the results may not reflect real operating conditions; the mathematical models used to determine the torque may be non-linear. This can lead to errors in measurements, especially at high or low torque values; indirect methods do not provide direct feedback about the real torque, which can lead to delays in process regulation and control. This can be critical for some applications where fast and accurate torque control is essential; indirect methods may be less efficient or unsuitable for some types of electric motors or applications. For example, when using high-frequency or multiphase motors, indirect methods may not provide sufficient accuracy or stability of measurements. The article examines algorithms for determining the rotational parameters of electric motors using indirect measurement methods. An analysis of the characteristics of electric motors according to their energy data was carried out. The measurement possibilities are determined based on the functional dependence of the torque on the power of the electric motor and the speed of rotation of its shaft. The characteristics of the power components are studied and the results of their simulation are given. An analysis of the methods of determining the angular velocity and angular acceleration of the electric motor shaft was carried out, and the role of these parameters in the determination of the torque was investigated. A two-channel network-type information and measurement system is proposed, which allows data collection and their visualization, where one channel is used to measure power, the other to measure shaft rotation speed.

Thermodynamics and Heat Transfer Analysis of Magnetized Casson Hybrid Nanofluid Flow via a Riga Plate with Thermal Radiation

The importance of non-Newtonian fluid (Casson fluid) in industry is increasingly appreciated. However, little is known about the flow rheology of Casson fluid flowing over a Riga plate. Thus, the purpose of this investigation is to examine the nature of entropy generation (EG) and heat transfer (HT) on Casson hybrid nanofluid flow past a Riga plate by considering the influences of magnetic field and thermal radiation. The Hamilton–Crosser (Model 1) and Xue model (Model 2) of thermal conductivity are incorporated for Casson hybrid nanofluid. The governing equations are solved by numerical methods i.e., bvp4c and shooting techniques. In the current framework, the comparative patterns for both models of temperature, velocities, EG and Bejan number are depicted due to the existing parameters. The domain of the pertinent parameters is taken as thermal radiation, [Formula: see text]; stretching parameter, [Formula: see text]; Casson factor, [Formula: see text]; rotation parameter, [Formula: see text]and Hartmann number, [Formula: see text]. The outcomes show that the rise in volume fraction and thermal conductivity profile of Xue model (Model 2) is better than Hamilton–Crosser model (Model 1). Moreover, EG profiles are escalated with augmentation in values of Hartmann number and stretching parameter for both models. The results of the study are useful for predicting the rheology of right fluid, while it also assists in safeguarding the boundary layer (BL) separation, along with establishing a parallel force to the surface in assisting the domain of science and technology.

Metrological Aspects of Controlling the Rotational Movement Parameters of the Auger for Dewatering Solid Waste in a Garbage Truck

Metrological Aspects of Controlling the Rotational Movement Parameters of the Auger for Dewatering Solid Waste in a Garbage Truck

The Conformations of Isolated Gallic Acid: A Laser-Ablation Rotational Study

The rotational spectrum of laser-ablated gallic acid has been recorded using CP-FTMW spectroscopy. Two rotamers have been detected, and their rotational spectra have been assigned and analyzed to obtain the molecular spectroscopic parameters. The observed rotamers have been unambiguously identified in the light of theoretical computations, based on the comparison of the experimental line intensities and rotational parameters with the rotational constants and electric dipole moments predicted from theoretical calculations. The values of the planar inertial moments confirm that the observed conformers are planar, and their relative stability and population have been determined from relative intensity measurements. The B3LYP-D3/6-311++G(2d,p) level has been shown to be the best method among a series of levels normally used to predict the rotational parameters in rotational spectroscopy. In the observed conformers, the three adjacent OH groups are arranged in a sequential form, and the only difference between them lies in the orientation of the COOH group. Although weak attractive OH···O interactions seem to exist, the analysis of the electron density topology does not show the existence of any critical point corresponding to these interactions.