Root Locus Research Articles

A Virtual Synchronous Generator Control Strategy Based on Transient Damping Compensation and Virtual Inertia Adaptation

To mitigate the challenges posed by transient oscillations and steady-state deviations in the traditional virtual synchronous generator (TVSG) that is subjected to active power and grid frequency disturbances, a VSG control strategy based on Transient Damping Compensation and Virtual Inertia Adaptation is presented. Initially, a closed-loop small-signal model for the grid-connected active power loop (APL) of the TVSG is constructed, which highlights the contradiction between the dynamic and static characteristics of TVSG output power through the analysis of root locus distribution trends. Secondly, a VSG control strategy based on Transient Damping Compensation (TDC) is proposed. The influence of APL system parameters introduced by TDC on system stability is qualitatively analyzed based on pole distribution trends and frequency response, and a comprehensive parameter design scheme is presented. In addition, based on the TDC algorithm, an improved virtual inertia adaptive strategy utilizing the Inverse Square Root Unit (ISRU) approach is designed, and the tuning range of parameters is provided. Finally, simulations and experiments verify that the proposed strategy exhibits superior active response performance and transient oscillation suppression capabilities, effectively eliminating active steady-state deviations caused by frequency disturbances in the power grid.

Integrated Extraction of Root Diameter and Location in Ground-Penetrating Radar Images via CycleGAN-Guided Multi-Task Neural Network

The diameter of roots is pivotal for studying subsurface root structure geometry. Yet, directly obtaining these parameters is challenging due their hidden nature. Ground-penetrating radar (GPR) offers a reproducible, nondestructive method for root detection, but estimating diameter from B-Scan images remains challenging. To address this, we developed the CycleGAN-guided multi-task neural network (CMT-Net). It comprises two subnetworks, YOLOv4-Hyperbolic Position and Diameter (YOLOv4-HPD) and CycleGAN. The YOLOv4-HPD is obtained by adding a regression header for predicting root diameter to YOLOv4-Hyperbola, which achieves the ability to simultaneously accurately locate root objects and estimate root diameter. The CycleGAN is used to solve the problem of the lack of a real root diameter training dataset for the YOLOv4-HPD model by migrating field-measured data domains to simulated data without altering root diameter information. We used simulated and field data to evaluate the model, showing its effectiveness in estimating root diameter. This study marks the first construction of a deep learning model for fully automatic root location and diameter extraction from GPR images, achieving an “Image Input–Parameter Output” end-to-end pattern. The model’s validation across various dataset scales opens the way for estimating other root attributes.

Advanced digital control strategies for switching buck converters: A modeling perspective

This paper highlights the significance of digital controllers over analog counterparts, emphasizing the utilization of optimization techniques such as MPC. It explores the benefits of adaptive controllers compared to MPC, showcasing simulations that dynamically adjust controller parameters to accommodate system and environmental variations. Addressing uncertainties, nonlinearities, and time-varying dynamics, the paper employs MPC-DC technique as an adaptive approach aiming to merge the advantages of digital controllers and MPC.The core concept revolves around leveraging the digital controller’s inherent advantages over analog counterparts and enhancing control precision through MPC, particularly in power converter applications. The study introduces a discrete root locus technique for digital controller design, focusing on DC-DC Buck Converters, with subsequent MPC fine-tuning. Demonstrating efficacy, the approach enhances switching converters’ performance, minimizing passive component size and costs while ensuring robust load and line regulation. Moreover, the proposed MPC based digital controller design methodology extends to other switching converters like Boost, Cuk, and Sepic Converters. Finally, the validation via MATLAB/Simulink simulations underscores the efficacy of the proposed model.

Use of CBCT in Orthodontics: A Scoping Review.

Objectives: The present scoping review aims to provide a panoramic view of the current state of knowledge, highlighting the strengths, limitations, and future directions, on the use of CBCT in orthodontic practice. Methods: This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines to identify eligible studies from the following databases: PubMed, Scopus, and Web of Science. The research question was formulated as follows: "What is the scientific evidence concerning the preferential use of 3D CBCT over 2D radiography in orthodontics"? Results: Through database searching, 521 records were identified, and ultimately, 37 studies that compared 3D CBCT with 2D conventional radiography were included. Of these, 16 articles regarded the use of CBCT for cephalometric analysis, 5 papers analyzed the evaluation of root resorption, 10 studies evaluated the diagnostic accuracy of root angulation and determining tooth position, and the remaining 6 articles were conducted for miscellaneous applications: determining the size of the nasopharyngeal airway (n = 2), miniscrew positioning (n = 1), estimating cervical vertebrae maturity (n = 1), and evaluating the correctness of the root location when placing digital indirect brackets (n = 1). Conclusions: The choice between 3D CBCT or CBCT-generated radiography and conventional 2D radiography in orthodontics involves careful consideration of the specific clinical context, the complexity of the case, and the balance between the diagnostic advantages and the associated limitations. Future Directions: Future studies with a prospective design and standardized imaging protocols are encouraged to facilitate the development of a consensus on the best practices.

Compact Analysis of the Necessity of Padé Approximation for Delayed Continuous-time Models in LQR, H-Infinity and Root Locus Control Strategies

This paper presents a comprehensive analysis of the need for the Padé approximation for continuous-time models with delays, focusing on its critical role in addressing the control challenges posed by time delays. Time delays, often referred to as dead times, transport delays or time lags, are inherent in a wide range of industrial and engineering processes. These delays introduce phase shifts that degrade control performance by reducing control bandwidth and threatening the stability of closed-loop systems. Accurate modelling and compensation of these delays is essential to maintain system stability and ensure effective control. This paper highlights the difficulties that arise when using advanced control techniques such as root locus (RL), linear quadratic regulator (LQR) and H-infinity (H_∞) control in systems with delays. Representing delays in exponential form leads to an infinite number of state problems, complicating the design and analysis of controllers in such systems. To address these challenges, the Padé approximation is proposed as an effective method for approximating time delays with rational polynomials of appropriate order. This approach allows for more accurate simulation, system analysis and controller design, thereby mitigating the problems caused by delays. The paper also provides a detailed comparative analysis between the Padé approximation and Taylor polynomials, demonstrating the superiority of the former in achieving accurate delay modelling and control performance. The results show that the use of Padé approximation not only improves the accuracy of system models, but also improves the robustness and stability of control strategies such as RL, LQR, and H_∞. These results highlight the importance of the Padé approximation as a valuable tool in the design of delay-affected control systems, offering significant advantages for both theoretical and practical applications.

Design and comparative analysis of motor position control based on traditional PID controller and fuzzy PID controller

Abstract. Using the PID algorithm to control electrical elements is a practical industrial application that have been studied for decades. This paper constructs a study on the difference between BLDC motor control and applying traditional PID and fuzzy PID. The simulation is done through Falstad and Matlab/Simulink. The math model of the transfer function of a BLDC motor is constructed by analyzing voltage and torque equilibrium. The parameters are determined approximately by looking up the datasheet of 2338 0006s. Then, Falstad establishes the operational amplifier model of the BLDC motor and traditional PID controller. The parameters are determined through both root locus and step response presented by Falstads scope. Next, Simulink is used to realize the fuzzy PID controller. The comparison study of traditional PID controller and fuzzy PID controller is constructed by looking at the scope and export data. After that, it is concluded that fuzzy PID controller performs better than traditional PID controller, it is robust and the influence of the input parameter is small. Finally, a lead lag compensator is applied to the whole system to improve the performance in the frequency domain.

Deep mantle plumes feeding periodic alignments of asthenospheric fingers beneath the central and southern Atlantic Ocean

High-resolution full waveform seismic tomography of the Earth's mantle beneath the south and central Atlantic Ocean brings into focus a series of asthenospheric low shear velocity channels, or "fingers" on both sides of the southern and central mid-Atlantic ridge (MAR), elongated in the direction of absolute plate motion with a spacing of [Formula: see text]1,800 to 2,000 km, and associated with bands of shallower residual seafloor depth anomalies that suggest channeled flow over thousands of kilometers. Each of the three most clearly resolved fingers on the African side of the MAR corresponds to a separate group of whole mantle plumes rooted in distinct patches at the core-mantle boundary, feeding hotspots, and volcanic lines with distinct isotopic signatures. Plumes of a given group appear to merge at the top of the lower mantle before separating again, suggesting interaction of deep mantle flow with a more vigorous mesoscale circulation in the upper mantle. The corresponding hotspots are generally offset from the location of the deep mantle plume roots. The distinct isotopic signatures of these hotspot groups are also detected in the mid-ocean ridge basalts at the location where the fingers meet the ridge. Meanwhile, at least some of the variability within each plume group could originate in the upper mantle and extended transition zone where plumes in a given group appear to merge and pond. This study also adds to mounting evidence that the African large low shear velocity province is not a uniform, unbroken pile of dense material rising high above the core-mantle boundary, but rather a collection of mantle plumes rooted in patches of distinct composition.

Active Support Pre-Synchronization Control and Stability Analysis Based on the Third-Order Model of Synchronous Machine

When traditional grid-forming converters directly participate in the grid-connected operation of the power grid, due to the lack of a pre-synchronization control system, the voltage amplitude and initial phase on both sides of the grid-connected point will deviate, resulting in voltage and current distortion during grid-connected mode. An active support phase-locked loop free pre-synchronization control strategy based on the third-order model of a synchronous generator is proposed to address the grid-connected problem of the grid-forming converter mentioned above. First, a model of active support control with frequency integral feedback at small signal levels was constructed. The root locus method was employed to examine how system parameters affect the stability of the active support control system. Second, by adding phase pre-synchronization controllers and amplitude pre-synchronization controllers to the active frequency loop and excitation voltage loop of the third-order model, it was ensured that the frequency, phase, and voltage amplitude of the unit are consistent with the power grid, achieving a fast and smooth grid-connected mode of the unit. Finally, by using a DC source to simulate all types of new energy power generation equipment, the active support pre-synchronization control system based on the three-order model of synchronous generator is built in the MATLAB/Simulink simulation environment, and the accuracy and effectiveness of the control strategy in this paper is verified.

Radiographic Predictors of Postoperative Inferior Alveolar Nerve Injury in Mandibular Third Molar Surgery

BackgroundCone-beam computed tomography (CBCT) provides additional three-dimensional information on the relationship between the mandibular third molar (M3M) and the inferior alveolar nerve (IAN). As such, CBCT is being increasingly utilized in pre-operative M3M assessment. PurposeThe purpose of the study was to compare the radiographic findings on panoramic and CBCT and their association with post-operative IAN paresthesia. Study design, setting and sampleWe conducted a retrospective cohort study in a sample of patients referred to the Department of Oral and Maxillofacial Surgery at the Royal Dental Hospital of Melbourne, for management of impacted M3Ms. Patients were included in this study if they had one or more high risk findings on OPG, had both OPG and CBCT imaging taken and if at least one M3M had been extracted. Subjects were excluded from this study if their M3Ms were not extracted or if a CBCT was not indicated. Independent variablesThe independent variable was radiographic features identified on OPG (Rood and Shehab’s radiographic signs, root morphology, impaction type, Pell and Gregory classification) and CBCT (number and location of roots, severity of IAN compression and the presence of ankylosis). Outcome variableThe outcome variable was post-operative neurosensory function defined as any reported paresthesia at 2-week post-procedural review. CovariatesThe covariates were patient demographic information (age, sex). AnalysesVariables were initially assessed with univariate logistic regression analysis to determine factors related to developing post-operative paresthesia. Multivariate logistic regression analysis was then used to assess the association between positive univariate study variables and post-operative paresthesia, while adjusting for potential confounders. Covariates were assessed using an omnibus likelihood ratio test and included if they were statistically significant at the p<0.05 level. ResultsThe study sample consisted of 257 subjects who underwent surgical removal of n=386 M3Ms. The mean age was 25.9 (SD = 7.05). The panoramic features of narrowing of canal, diversion of canal and dark/bifid roots were identified as statistically significant associations of post-operative paresthesia. No CBCT features were significantly associated of post-operative paresthesia. Conclusions and RelevanceCertain panoramic features, along with patient age, are significant predictors of IAN paresthesia. CBCT findings were not significant predictors upon multivariate analysis, thus additional CBCT imaging did not significantly improve ability to predict paresthesia.

Closed‐form optimal solution of two‐degree‐of‐freedom system with Inerter based on equal modal damping with potential application in non‐structural elevator for seismic control

AbstractTargeting the great demand for adding non‐structural elevators to old residential buildings, this article proposes an updated configuration of tuned mass damper inerter (U‐TMDI) applied in external non‐structural elevators. An analog 2‐DOF system is established to describe the residential building controlled by an inerter elevator. Then, three closed‐form optimal solutions for designing the U‐TMDI are derived via the fixed‐point method, equal modal damping criterion, and the infinity damping assumption. Subsequently, these optimal solutions are compared and discussed involving the expressions of tuning frequency ratio and the optimal damping parameters, root locus diagram and supplemental damping ratios, transfer function, and robustness to frequency variation, respectively. Finally, a residential building example is adopted to validate the feasibility of the proposed retrofitting strategy and the closed‐form optimal design solutions. It is demonstrated that the optimal tuning frequency ratios derived by the fixed‐point method and equal modal damping criterion are different for U‐TMDI due to the influence of elevator stiffness ratio , while its degradation forms for tuned mass damper (TMD) are identical, recognizing the importance of the elevator stiffness. Moreover, the proposed retrofitting strategy of using an inerter elevator can significantly mitigate the main structure displacement by about 18%∼23% for both far‐field and near‐fault earthquakes.

A Transient Damping Improvement Strategy for Enhancing Grid-Connected Active Power Response Performance of VSG

The given power and grid frequency disturbances can cause transient oscillations and steady-state deviations in the output power of a virtual synchronous generator (VSG), which can be effectively addressed by adding transient damping. However, this approach may result in significant power overshoot. This article proposes an improved VSG control strategy based on transient electromagnetic power feedback compensation and a small-signal model reduction scheme. Firstly, the grid-connected active closed-loop small-signal models of typical VSG control and transient damping VSG control are established, respectively. The transient oscillation suppression mechanism of active power is revealed through root locus and frequency response analyses, and the power overshoot characteristics of the two control strategies are analysed by combining them with the system of zero points. Secondly, the active transient feedback compensation method and the small-signal model reduction design method are introduced in detail. Finally, comparative analysis experiments are conducted using the Matlab/Simulink and hardware-in-the-loop experimental platform. It is verified that the proposed control strategy can suppress transient oscillations in active power, prevent steady-state deviations, and effectively mitigate the power overshoot problem of the system.

Mathematical Methods for Control Systems in Electrical Engineering

Control frameworks are exceptionally imperative in electrical building since they make it conceivable to absolutely control and move forward complicated gadgets and forms. This unique talks almost essential scientific procedures that are required to get it and construct control frameworks within the field of electrical designing. Through science structures, it appears vital thoughts like criticism control, soundness examination, and framework optimization. Differential conditions, which depict how energetic frameworks carry on, are the building squares of control frameworks. These conditions appear how framework variables are associated to each other and how quick they alter over time. They are utilized to ponder how frameworks move and remain steady. These forms decide how electric circuits, engines, generators, and other critical parts of advanced innovation foundation work in electrical building employments. The thought of control gives us ways to form these frameworks more steady, controlled, and successful. Differential conditions can be effectively interpreted into the recurrence space utilizing strategies like Laplace changes. This makes it simpler to think about how frameworks react to distinctive inputs and changes. This alter makes it less demanding to figure out framework exchange capacities, which makes a difference when making controls that alter how frameworks carry on to meet execution objectives. Steadiness investigation too makes beyond any doubt that controlled frameworks work reliably and typically indeed when conditions alter. Strategies like root locus, Nyquist measure, and Bode plots offer assistance us get it the limits of a system's steadiness and how it reacts, which is vital for making beyond any doubt it works well and anticipating undesirable variances or insecurity.

On the mechanism of transonic buzz passive suppression with global stability analysis

The control surface buzz may occur when the aircraft cruise at transonic Mach numbers, which would may lead to flight accidents. Transonic buzz could be a problem in aircraft design. The triggering of transonic buzz has been investigated in the previous publications. It is essentially a single degree of freedom flutter caused by the coupling of one structural mode and one pre-instability flow mode, thus, type A/B buzz usually occurs close to the buffet onset. With this mechanism, the buzz can be suppressed by improving the flow stability and buffet onset. Three buffet passive control techniques are applied to test the suppression effect on transonic buzz. The relationship between the flow stability and buzz onset is studied to verify the mechanism of buzz. CFD simulation and global stability analysis are applied to compute the flow stability with and without control techniques. Results show that, three control techniques can improve the flow stability and postpone the buffet onset. Meanwhile the buzz can be effectively suppressed. With the aeroelastic ROM and the root loci method, the coupling process between the structural mode and the controlled flow modes are revealed, indicating the buzz suppression effects are positively correlated with its improvement of the flow stability with control. This study can help to understand the mechanism of buzz deeply and propose the new thought of buzz suppression.

Frequency Coordination Control Strategy for Large-Scale Wind Power Transmission Systems Based on Hybrid DC Transmission Technology with Deep Q Network Assistance

Wind power is currently the most mature representative of sustainable energy generation technology, which has been developed and utilized on a large scale worldwide. The random and fluctuating nature of wind power output poses a threat to the secure and stable operation of the system. Consequently, the transmission of wind power has garnered considerable attention as a crucial factor in mitigating the challenges associated with wind power integration. In this paper, an artificial-intelligence-aided frequency coordination control strategy applicable to wind power transmission systems based on hybrid DC transmission technology is proposed. The line commutated converter (LCC) station at the sending end implements the strategy of auxiliary frequency control (AFC) and automatic generation control (AGC) to cooperate with each other in order to assist the system frequency regulation. The AFC controller is designed based on the variable forgetting factor recursive least squares (VFF-RLS) algorithm for system identification. First, the VFF-RLS algorithm is used to identify the open-loop transfer function of the system. Then, the AFC controller is designed based on the root locus method to achieve precise control of the system frequency. The DC line power modulation quantity is introduced in the AGC to automatically track the active power fluctuation and frequency deviation of the system. The AGC utilizes the classical proportional-integral (PI) control. By selecting the integrated time absolute error (ITAE) performance index to construct the reward function, and using a deep Q-network (DQN) for controller parameter optimization, it achieves improved regulation performance for the AGC. The voltage source converter (VSC) station at the receiving end implements an adaptive DC voltage droop control (ADC)strategy. Finally, the effectiveness and robustness of the proposed frequency control strategy are verified through simulation experiments.

Comparison between an Adaptive Gain Scheduling Control Strategy and a Fuzzy Multimodel Intelligent Control Applied to the Speed Control of Non-Holonomic Robots

The main objective of this work is to address problems related to the speed control of mobile robots with non-holonomic constraints and differential traction—specifically, robots for football games in the VSS (Very Small Size) category. To achieve this objective, an implementation and comparison is carried out between two control strategies: an adaptive control strategy by gain scheduling and a fuzzy multimodel intelligent control strategy. The mathematical models of the wheel motors for each operating range are approximated by a first-order system since data acquisition is performed using the step response. Tuning of the proportional and integral gains of the local controllers is carried out using the root locus technique in discrete time. For each mathematical model obtained for an operating range, a local controller is tuned. Finally, with the local controllers in hand, the implementation of and comparison between the gain scheduling adaptive control strategy and the fuzzy multimodel intelligent control strategy are carried out, in which the control strategies are programmed into the low-level code of a non-holonomic robot with a differential drive to verify the performance of the speed tracking dynamics imposed on the wheel motors to improve robot navigation during a robot football match.

On the electromechanical bandgap of microscale vibration isolation metamaterial beams with flexoelectric effect

In this paper, a type of metamaterial isolation beam consisting a cantilever beam with flexoelectric film attached is provided. Electrodes interconnect on the surface to create parallel resonant shunt circuits, enabling band-stop filtering. The electromechanical control equations are derived using the Hamiltonian principle. A closed-form analytical expression for the bandgap range is obtained via the root locus method. Theoretical results are validated through finite element methods. Findings reveal that the operational bandgap of millimeter-scale flexoelectric metamaterial isolation beams is 5.2 times greater than that of conventional piezoelectric metamaterial beams. Furthermore, the vibration excitation amplitude is reduced by 99.9%. These results highlight the significant advantages of flexoelectric materials for microscale high-frequency passive isolation, providing superior stability in complex vibration environments. The research investigates the effects of end mass, electrode plate count, and external resistance on the vibration isolation performance of flexoelectric metamaterial beams. The study also examines the variations in relative bandgap width between flexoelectric and piezoelectric metamaterial beams concerning material, size, and structural parameters, identifying optimal values. Notable differences in bandgap characteristics are observed between flexoelectric and piezoelectric beams; for instance, while piezoelectric beams have an optimal substrate elastic modulus, flexoelectric beams do not, and the optimal film thickness for flexoelectric beams is 2.2 times that for piezoelectric beams.

Influence of nonlinear motor suspension parameters on Hopf bifurcation characteristics of high-speed bogie

A dynamic model of the bogie was established to investigate the influence of the elastic suspension of the motor and some nonlinear terms on the stability of vehicle hunting motion. Linear analysis was conducted based on the root locus method and other methods, and the influence of the elastic suspension of the motor on the linear critical speed was studied. Then, based on research on linear stability, the impact of the first Lyapunov coefficient of the model on the Hopf bifurcation type was analyzed. Subsequently, the influence of the stiffness and damping cubic terms in the motor suspension on the first Lyapunov coefficient was studied, and the possibility of controlling the Hopf bifurcation type by changing the stiffness and damping cubic terms in the motor suspension was analyzed, and relevant research was conducted. The results show that the increase of the cubic term of stiffness increased the corresponding speed when the amplitude of the limit cycle was 8 mm by about 3.4 km/h, and the increase of the cubic term of damping increased the corresponding speed when the amplitude of the limit cycle was 8 mm by about 8.9 km/h. Finally, a time-domain diagram corresponding to systems with different motor suspension stiffness and damping cubic terms was presented, further explaining the role of the motor suspension cubic terms and conducting relevant validation, providing reference opinions for the design of the motor elastic suspension of multiple units.

Exact dispersion relation of the quantum Langmuir wave.

The normal modes, i.e., the eigensolutions to the dispersion relation equation, are the most fundamental properties of a plasma. The real part indicates the intrinsic oscillation frequency while the imaginary part the Landau damping rate. In most of the literature, the normal modes of quantum plasmas are obtained by means of small damping approximation, which is invalid for high-k modes. In this paper, we solve the exact dispersion relations via the analytical continuation scheme, and, due to the multi-value nature of the Fermi-Dirac distribution, reformation of the complex Riemann surface is required. It is found that the topological shape of the root locus in quantum plasmas is quite different from classical ones, in which both real and imaginary frequencies of high-k modes increase with k steeper than the typical linear behavior in classical plasmas. As a result, the time-evolving behavior of a high-k initial perturbation becomes ballistic-like in quantum plasmas.

Three-dimensional image analysis specifies the root distribution for drought avoidance in the early growth stage of rice.

Root system architecture (RSA) plays a key role in plant adaptation to drought, because deep rooting enables better water uptake than shallow rooting under terminal drought. Understanding RSA during early plant development is essential for improving crop yields, because early drought can affect subsequent shoot growth. Herein, we demonstrate that root distribution in the topsoil significantly impacts shoot growth during the early stages of rice (Oryza sativa) development under drought, as assessed through three-dimensional image analysis. We used 109 F12 recombinant inbred lines obtained from a cross between shallow-rooting lowland rice and deep-rooting upland rice, representing a population with diverse RSA. We applied a moderate drought during the early development of rice grown in a plant pot (25 cm in height) by stopping irrigation 14 days after sowing. Time-series RSA at 14, 21 and 28 days after sowing was visualized by X-ray computed tomography and, subsequently, compared between drought and well-watered conditions. After this analysis, we investigated drought-avoidant RSA further by testing 20 randomly selected recombinant inbred lines in drought conditions. We inferred the root location that most influences shoot growth using a hierarchical Bayes approach: the root segment depth that impacted shoot growth positively ranged between 1.7 and 3.4 cm in drought conditions and between 0.0 and 1.7 cm in well-watered conditions. Drought-avoidant recombinant inbred lines had a higher root density in the lower layers of the topsoil compared with the others. Fine classification of soil layers using three-dimensional image analysis revealed that increasing root density in the lower layers of the topsoil, rather than in the subsoil, is advantageous for drought avoidance during the early growth stage of rice.

Influences of root fragments on soil thermal property measurements with heat pulse method

Heat pulse (HP) method has been widely applied for measuring thermal properties, heat fluxes, and soil–water evaporation for near-surface soil layers. In topsoil layers, the presence of roots violates the underlying assumption of HP method that the soil under test is homogeneous. In this study, numerical and laboratory experiments were conducted to test the influence of root fragments on soil thermal property measurement with HP sensors. Soybean root fragments, with a water content of about 0.74 m3 m−3 and diameters ranging from 0.5 to 4 mm, were carefully repacked into soil samples that were used for HP measurements. Results showed that the effects of roots on soil thermal property measurements depended on root size, root location and directions relative to the heater probe, and the thermal property differences between soil sample and root. Roots showed negligible influence on heat pulse data when the root fragments were positioned outside the HP measurement region (more than probe space away from heater probe), or root diameters (d) were less than 1 mm, or in oven-dried soil samples. On relatively wet soils (i.e., with water content of 0.05–0.25 m3 m−3), when root fragments were located in between the heater and sensing probes (parallel to the probe planes), (1) the heat capacity (C) and thermal conductivity (λ) differences between root-free soil and root-soil mixture increased proportionally with d increased from 1 mm to 4 mm; (2) the differences in absolute values of C and λ between the root-free soil and soil-root mixture were highly dependent on soil water content. The errors in soil C and λ estimates were larger when the root fragment was parallel with than perpendicular to or inclined 45 degrees to the probe plane, and the error overall decreased with a smaller ρb and sand fraction. When the root fragments were positioned within the HP measurement region, or d were larger than 1 mm, or in relatively wet soil samples, it is important to consider root effect when interpreting HP signals.