Control Of Composition Research Articles

Utilisation of in situ formed cyano-bridged coordination polymers as precursors of supported Ir-Ni alloy nanoparticles with precisely controlled compositions and sizes.

Ir-Ni alloys supported on SiO2 have been reported to show high catalytic activity for styrene hydrogenation; however, precise control of compositions and sizes of the Ir-Ni alloys is difficult when conventional metal salts are used as precursors. Furthermore, the concomitant formation of unalloyed Ni nanoparticles disturbs quantitative discussion about Ir-Ni alloy compositions. We report herein a preparation method of Ir-Ni alloys with precisely controlled compositions on SiO2 using Ni(NO3)2 and an Ir complex possessing CN- ligands, [Ir(CN)6]3- or [Ir(ppy)2(CN)2]- (ppy = 2-phenylpyridine), as precursors. The in situ formation of cyano-bridged coordination polymers involving Ir and Ni promotes the formation of Ir-Ni alloys, whose compositions are virtually the same as expected from the amounts of Ir and Ni used for the preparation, after heat treatment under H2. The use of [Ir(ppy)2(CN)2]- as the precursor resulted in the formation of smaller Ir-Ni alloy particles than those with [Ir(CN)6]3- related to the structures of the formed coordination polymers.

A Composite Control Method Based on Model Predictive Control and a Disturbance Observer for the Acquisition, Tracking, and Pointing System

Nonlinear disturbances, such as friction, backlash, and base vibration, are the main factors restricting the further improvement of the dynamic performance of the Acquisition, Tracking and Pointing (ATP) system. However, the modeling and compensation of the time-varying nonlinearities are still challenging. In this paper, a compound control algorithm based on model predictive control (MPC) and a Proportional Multiple-Integral State-Augmented Kalman Filter (PMISAKF) disturbance observer is proposed to improve the disturbance rejection performance. Specifically, a PMISAKF is used to estimate the system’s state and external disturbances in real-time. These observed disturbances are then treated as known external inputs at the current or future time points and incorporated into the predictive model of MPC. This allows the optimization process to take these external factors into consideration, enabling the calculation of an optimal control strategy and achieving high pointing and tracking accuracy for nonlinear time-varying disturbances. Experimental results show that the proposed method can effectively improve the system’s anti-interference ability and tracking accuracy.

Design and verification of a novel energy-efficient pump-valve primary-auxiliary electro-hydraulic steering system for multi-axle heavy vehicles

Multi-axle heavy vehicles employ a variable-length tie rod steering system to achieve precise multi-mode steering. However, the single-axle steering system need integrate two sets of electro-hydraulic control systems (EHCSs), resulting in the energy consumption significant increase. This paper proposes a novel energy-efficient pump-valve primary-auxiliary electro-hydraulic steering system (PVPA EHSS) which compose of a pump-controlled dual-steering cylinders primary system and a valve-controlled variable-length tie rod cylinder auxiliary system. The proposed system utilizes a single pump to drive both the primary and auxiliary EHCSs simultaneously, enabling high-precision and high-efficiency steering with multi steering modes. Additionally, to suppress the flow disturbance of the auxiliary system branch flow on the single-pump-controlled steering primary system, the interaction between the flow of the auxiliary system and the flow of the primary system in each steering phase is studied. A pump flow feedforward-angle feedback composite control strategy incorporating branch flow prediction is proposed to mitigate the disturbance and ensure the accurate steering of left and right tires. The experimental results demonstrate that compared to the traditional variable-length tie rod steering system, the proposed system reduces energy consumption by 58.66 %, and achieves precise adaptation of the left and right tire angles in multi steering modes.

Reliable Finite‐Time Control for Nonlinear Chaotic Semi‐Markov Jump Systems With Incomplete Transition Rates

ABSTRACTThis article studies the finite‐time control problem for a class of nonlinear chaotic semi‐Markov jump systems with incomplete transition rates described by the T‐S fuzzy model approach. As a means to depict the dynamical properties pertaining to the examined system, parametric uncertainties, faults, external disturbances and input saturation are taken into consideration. The foremost objective of this study is to come up with a composite control mechanism that effectively rejects and attenuates the repercussions of faults and disturbances. In particular, we primarily built a disturbance observer in order to obtain a precise estimation of the external disturbances. After which, the fault diagnosis observer is designated to effectively estimate the faults. Specifically, a composite reliable control mechanism is developed by fusing the output of the constructed observers with the mode‐dependent fuzzy‐rule based state feedback controller. By employing suitable Lyapunov functions in conjunction with the linear matrix inequality technique, a set of mode‐dependent conditions is derived to ensure the finite‐time stochastic boundedness of the underlying closed‐loop and estimation error systems. Following this, the anticipated controller and observer gain matrices are elicited by resolving the established linear matrix inequalities. Thereafter, intending to ascertain the efficacy and usefulness of accrued theoretical findings, simulation results performed on Chua's circuit system is endowed.

Harnessing Prebiotics to Improve Type 2 Diabetes Outcomes.

The gut microbiota, a complex ecosystem of microorganisms in the human gastrointestinal tract (GI), plays a crucial role in maintaining metabolic health and influencing disease susceptibility. Dysbiosis, or an imbalance in gut microbiota, has been linked to the development of type 2 diabetes mellitus (T2DM) through mechanisms such as reduced glucose tolerance and increased insulin resistance. A balanced gut microbiota, or eubiosis, is associated with improved glucose metabolism and insulin sensitivity, potentially reducing the risk of diabetes-related complications. Various strategies, including the use of prebiotics like inulin, fructooligosaccharides, galactooligosaccharides, resistant starch, pectic oligosaccharides, polyphenols, β-glucan, and Dendrobium officinale have been shown to improve gut microbial composition and support glycemic control in T2DM patients. These prebiotics can directly impact blood sugar levels while promoting the growth of beneficial bacteria, thus enhancing glycemic control. Studies have shown that T2DM patients often exhibit a decrease in beneficial butyrate-producing bacteria, like Roseburia and Faecalibacterium, and an increase in harmful bacteria, such as Escherichia and Prevotella. This review aims to explore the effects of different prebiotics on T2DM, their impact on gut microbiota composition, and the potential for personalized dietary interventions to optimize diabetes management and improve overall health outcomes.

Construction of a 3D spider web structure with spherical Ho2O3 wrapped by carbon nanofibers for high-efficiency microwave absorption and corrosion protection

Reasonable composition control and microstructure design are the effective ways to realize multi-functional high-performance absorbing materials. In this work, a three-dimensional (3D) spider web structure was designed by the electrospinning and high temperature carbonization technology, where Ho2O3 spheres were wrapped by carbon nanofibers. Herein, the spherical Ho2O3 were surrounded by layers of carbon nanofibers (spider silk), which were like the preys inside the spider's web. This unique bionic structure working in conjunction with the tuned components enables the as-prepared composites with improved impedance matching and enhanced loss capacity. The superior electromagnetic wave absorption performance was obtained as the minimum reflection loss of −61.37 dB at 2.90 mm and the maximum effective absorption bandwidth of 6.88 GHz (11.12–18 GHz) at 2.64 mm. At a thickness of 3.44 mm, the effective absorption bandwidth is 4.80 GHz (8–12.80 GHz), covering the entire X-band. At the same time, the composite soaked in the corrosive medium for 7 days owns a low corrosion current density (10−4 ∼10−6 A cm−2) and a high polarization resistance (105∼107 Ω), which exhibits the obvious anticorrosion ability. This work designs a specific spider web structure with high-performance microwave absorption and corrosion protection.

Weld Pool Flow Characteristics in Double-Wire Arc Welding of Aluminum Alloys: Research by Numerical Simulations

Double-wire arc welding involves simultaneously feeding two wires into a molten pool, improving the efficiency and flexibility of traditional welding techniques. However, the interactions between the two wires and the molten pools are complex, which increases the difficulties in process and composition control. This work focuses on the weld pool flow characteristics in double-wire TIG arc welding. A CFD model incorporating a liquid bridge transfer model was developed to simulate the fluid flow phenomenon. Results show that the bead-forming appearances and flow characteristics of double-wire arc welding show no significant differences from single-wire arc welding. Welding current and welding speed have significant effects on the weld bead dimensions, while only welding current has effects on the flow characteristics. Wire feed XOZ angles show no significant influences on weld bead forming appearances and molten pool flow characteristics. Wire feed XOY angles influence the symmetry of the weld bead and the fluid flow. In 5B71/7055 heterogeneous double-wire arc welding, achieving a uniform distribution of alloy elements is difficult due to the complex convection patterns within the molten pool.

Anion Exchange and Lateral Heterostructure Formation in Ferromagnetic PEA2Cr(Cl,Br)4 Two-Dimensional Perovskites.

Postsynthetic vapor-phase anion exchange in the ferromagnetic two-dimensional (2D) hybrid metal-halide perovskite, PEA2CrCl4 (PEA+ = phenethylammonium), is reported. Anion exchange using vaporous trimethylsilyl bromide (TMS-Br) is shown to drive complete conversion of solution-processed PEA2CrCl4 polycrystalline thin films to PEA2CrBr4. Low-temperature magnetic circular dichroism spectroscopy indicates ferromagnetic ordering in these PEA2CrCl4 and PEA2CrBr4 films. Via partial anion exchange of exfoliated flakes of PEA2CrCl4 single crystals, we demonstrate that it is possible to generate abrupt lateral PEA2CrCl4/PEA2CrBr4 magneto-heterointerfaces. Kinetic studies reveal that lateral heterostructure formation is dictated by rapid edge-site halide exchange followed by slower intralayer bromide diffusion, and there is negligible interlayer (3D) bromide or TMS-Br diffusion. The importance of the bulky PEA+ interlayer cation in suppressing 3D diffusion is highlighted by parallel anion-exchange experiments on MA2CrCl4 (MA+ = methylammonium), which instead show 3D exchange. Comparison of anion-exchange reactions in PEA2CrCl4, PEA2MnCl4, and PEA2PbCl4 shows that 2D bromide diffusion is slowest in PEA2CrCl4, attributed to the antiferrodistortive ordering found in this composition. In addition to demonstrating both postsynthetic composition control and heterostructure formation in ferromagnetic Cr-based 2D perovskites for the first time, these results also advance our fundamental understanding of ion-exchange processes in this relatively unexplored family of 2D perovskites, broadening opportunities for investigation and control of novel spin effects in low-dimensional metal-halide perovskites.

Fine-tuning syngas composition using laser surface modified silver electrode for CO2 electroreduction

Electrochemical reduction of CO2 and H2O to synthesize gas (H2 and CO mixture) is of significant interest due to established industrial pathways to tune the H2 to CO composition to generate an array of valuable products including methanol, synthetic fuel, synthetic natural gas, and hydrogen. However, controlled H2:CO ratios are challenging on CO-active electrocatalysts like silver. We demonstrate that applying laser engineering to adjust the surface wetting state of a silver electrocatalyst with water contact angles θw ranging from 47° and 135°, H2:CO ratios can be tuned from 1 to 4 at modest potentials (−0.7 V versus RHE, RHE—reversible hydrogen electrode) with almost total unity Faradaic efficiency. Both hydrophilic (θw = 47°) and more hydrophobic (θw = 135°) samples showed an increasing H2:CO trend with rising potentials (0.7–1.2 V versus RHE) due to mass transport. Conversely, silver electrocatalyst with θw = 110° exhibited a constant H2:CO ratio of 4. This indicates catalyst wettability potentially affects *H and *HOCO intermediates’ adsorption, impacting H2:CO ratios. Our results show the feasibility of syngas composition control on silver catalysts via surface wettability, providing a simpler alternative to complex multicomponent electrocatalytic systems.

Design of Neural Network-Based Multi-Fault Tolerant Control System for Unmanned Aerial Vehicles

Actuator failure seriously threatens the flight safety of unmanned helicopters. Considering the problem of multiple faults such as actuator bias and failure in unmanned helicopters, a composite fault-tolerant flight control algorithm is proposed. For actuator bias fault, a nonlinear fault observer is designed to estimate it in real time; for actuator failure fault, a same-dimensional auxiliary system is constructed and processed by neural network technology. The composite fault-tolerant flight controller of the unmanned helicopter is designed by backstepping method, and the Lyapunov stability theory is used to prove that the error signals of the closed-loop system are bounded and convergent. Simulation results show that the proposed control algorithm can improve the fault tolerance of the unmanned helicopter when multiple actuator faults occur, ensuring its safe flight.

Trajectory tracking control of underwater tracked vehicle considering ICR longitudinal deviation compensation

During the operation of an underwater tracked vehicle on a soft substrate, the instantaneous center of rotation (ICR) no longer coincides with the geometric center after the longitudinal offset is accounted for by the external environment. Due to this, designing an underwater trajectory tracking system based on a kinematic model is a challenging task. In order to achieve the high-precision trajectory tracking control of underwater tracked vehicles, this paper proposes a trajectory tracking algorithm based on the kinematic model of tracked vehicles. First, an inverse tangent algorithm is proposed to address the problem that the front viewpoint of the Stanley algorithm may not be on the target path and cause deviation. Second, by using the inverse tangent algorithm to introduce the target bow angle, as well as combining the mechanisms by which biological endocrine hormones are regulated with the advantages of single-neuron proportional–integral–derivative (PID), a composite endocrine intelligent control law is proposed for the design of the lateral control law of an underwater tracked vehicle; a longitudinal control law is designed based on the longitudinal offset of the ICR obtained by the estimation of the unscented Kalman filter as a means of compensating for longitudinal errors. Finally, a kinematic model is used in order to determine the desired drive wheel speed of the underwater tracked vehicle. The method is compared with the method without longitudinal deviation compensation, then with the methods presented in related literature, and finally, a certain degree of experimental validation is carried out. These results validate the effectiveness of the proposed method.

8261 Achievement of Diabetes Treatment Goals in Mexico from 2016 to 2022

Abstract Disclosure: D. Ramirez Garcia: None. C.A. Fermin Martinez: None. P.N. Mendez Labra: None. N.E. Antonio Villa: None. J.A. Seiglie: None. O.Y. Bello-Chavolla: None. Background: Optimal diabetes care involves achieving goals with treatment in key metabolic parameters including HbA1c, blood pressure (BP), low density lipoprotein cholesterol (LDL-C) levels, and smoking cessation. Evaluation of diabetes care in Mexico has been incomplete, with previous studies focusing primarily on glycemic control, but not on a comprehensive analysis of combined treatment targets. Objective: To estimate achievement of diabetes treatment goals (HbA1c [A], BP [B], LDL-C [C], smoking cessation [N], and combined targets [AB, BC, AC, ABC, ABCN]) using data from nationally representative surveys from 2016-2022 among individuals with diagnosed diabetes in Mexico. Methods: We analyzed serial cross-sectional National Health and Nutrition Surveys from 2016-2022. A total of 2,689 adults with diagnosed diabetes ≥20 years were identified amongst 21,248 adults ≥20 years. Weighted prevalence estimates were obtained for glycemic control (HbA1c <7% in those <65 years, and <7.5% in those ≥65 years), BP control (<130/80 mmHg), LDL-C control (<70 mg/dL), smoking cessation, and combined targets. We also fitted logistic regression models to estimate the odds of achieving treatment targets according to age, sex, educational level, indigenous identity, and survey cycle. Results: In 2022, the prevalence of HbA1c, BP, and LDL-C control among individuals with diagnosed diabetes in Mexico was 41.2% (95% CI 30.5-52.0%), 46.0% (95% CI 36.5-55.5%), and 17% (95% CI 10.2-25.2%), respectively. Non-smoking prevalence was 92.4% (95% CI 88.6-96.2%). Combined target achievement was low, with a prevalence of 10.8% (95%CI 6.2-15.5%) for BC and 4% (95% CI 1.7-6.3%) for ABCN. The proportion of goal achievement was relatively stable across 2016-2022 for every parameter analyzed, except for LDL-C. LDL-C had the lowest proportion of control across all cycles, although a gradual increase was observed: 8.1% (95% CI 4-12.3%) in 2016 to 17% (95% CI 10.2-25.2%) in 2022. The increase in LDL-C control coincides with greater prevalence of statin use across survey cycles. Men had lower odds of achieving ABCN combined control (OR 0.49, 95%CI 0.45-0.54) than women. Similarly, compared with individuals <45 years, participants 45-64 years (OR 0.36, 95%CI 0.32-0.40) and ≥65 years (OR 0.41 95%CI 0.35-0.47) had lower odds of achieving composite control. Conclusions: Achievement of diabetes treatment goals in Mexico is suboptimal. Less than half of individuals with diagnosed diabetes achieve HbA1c or BP goals, less than a fifth achieve LDL-C control, and only 1 in 20 individuals achieve ABCN control. Greater efforts are needed to the improve the comprehensive care of individuals with diabetes in Mexico. Presentation: 6/3/2024

Active vibration isolation support platform for double crystal monochromator

The quality of the beamline at a synchrotron light source is directly related to the performance of the double crystal monochromator. This paper presents a designed active vibration isolation support platform for the double-crystal monochromator to meet the higher stability demands of advancing synchrotron light sources. The platform has good decoupling characteristics through the redundant structure of eight actuators mixed with active and passive. A vibration isolation control scheme is designed based on distributed degrees of freedom and a feed-forward feedback composite control scheme to ensure high stiffness of the support platform while achieving full-band vibration isolation. Finally, constructed a verification platform for an active vibration isolation system and verified the effectiveness of the proposed control method through experiments. With the designed active vibration isolation algorithm, the system can achieve full-band vibration isolation within the 1–100 Hz bandwidth.

Chalcogen and halogen surface termination coverage in MXenes—structure, stability, and properties

MXenes are a diverse family of two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides. They can be synthesized through both top-down approaches, such as selective etching of A-layers from MAX phases using acids or molten salts, and bottom-up approaches, such as direct synthesis using chemical vapor deposition. However, the degree of the surface termination coverage depends on the synthesis route and is one key parameter for controlling its properties. This study focuses on halogen- and chalcogen-terminated MXenes, particularly M2CTx where M = Ti, Zr, V, Nb, Ta, and T = S, Se, Te, Cl, Br, I, and with surface termination coverage ranging from 100% (ideal, x = 2) to 50% (x = 1). The incorporation of oxygen on vacant termination sites was also evaluated. Using density functional theory (DFT) calculations, we investigated the structural, electronic, and mechanical properties of these MXenes. Our findings reveal that non-ideal termination coverage (x < 2) is more favorable for MXenes terminated with a larger size of T, such as Ti2CBrx, Nb2CClx, and Ta2CClx, and leads to mixed termination sites and lower binding energies. A reduced binding energy may facilitate delamination into single sheets, however, too low termination coverage may also cause structural collapse. Electronic properties showed an increased number of states at the Fermi level under non-ideal coverage, potentially enhancing the conductivity. Mechanically, we find the moduli of MXenes to be comparable to other 2D materials, such as transition metal chalcogenides and hexagonal boron nitride, indicating their suitability for applications requiring flexibility and durability. This study underscores the potential of tailoring MXene properties through precise control of termination coverage and composition, paving the way for enhanced application-specific performance.

Decentralized control of ideal ternary reactive distillation column with inert

Decentralized control of an ideal hypothetical ternary reactive distillation column with an inert component is explored. Both composition measurement based and temperature inferential control structures are designed using simple heuristic approaches (two and three-point). The three-point composition control structure is proposed for the example RD column for the first time in this work. Although stable closed loop responses are seen for the throughput changes for all, the two-point structures have failed to achieve tight control of the product purity in the bottoms or purity of inert in the distillate for the inert composition changes due to fixed reflux ratio. The performances of the three-point control structures for the inert composition changes are quite satisfactory due to the indirect manipulation of the reflux ratio. The independent manipulation of the reflux rate and distillate (instead of fixed reflux ratio policy) is an important control decision for the successful regulation of the example RD column.

Composite anti-disturbance predictive control of unmanned systems with time-delay using multi-dimensional Taylor network

A composite anti-disturbance predictive control strategy employing a Multi-dimensional Taylor Network (MTN) is presented for unmanned systems subject to time-delay and multi-source disturbances. First, the multi-source disturbances are addressed according to their specific characteristics as follows: (A) an MTN data-driven model, which is used for uncertainty description, is designed accompanied with the mechanism model to represent the unmanned systems; (B) an adaptive MTN filter is used to remove the influence of the internal disturbance; (C) an MTN disturbance observer is constructed to estimate and compensate for the influence of the external disturbance; (D) the Extended Kalman Filter (EKF) algorithm is utilized as the learning mechanism for MTNs. Second, to address the time-delay effect, a recursive τ−step-ahead MTN predictive model is designed utilizing recursive technology, aiming to mitigate the impact of time-delay, and the EKF algorithm is employed as its learning mechanism. Then, the MTN predictive control law is designed based on the quadratic performance index. By implementing the proposed composite controller to unmanned systems, simultaneous feedforward compensation and feedback suppression to the multi-source disturbances are conducted. Finally, the convergence of the MTN and the stability of the closed-loop system are established utilizing the Lyapunov theorem. Two exemplary applications of unmanned systems involving unmanned vehicle and rigid spacecraft are presented to validate the effectiveness of the proposed approach.

Active disturbance rejection control for spacecraft relative motion in libration point orbits subject to actuator saturation and time-delays

This paper proposes a novel active disturbance rejection control (ADRC) scheme to achieve the spacecraft relative pose synchronization in the libration orbits under the constrations of the actuator saturation and time-delays. The relative kinematics and dynamics between two spacecraft are modeled using dual quaternions to avoid singularity. A set of dimensionless variables is introduced to improve computational accuracy. An extended state observer, consisting of a time-delay predictor and an anti-windup compensator, is designed to address actuator saturation and communication time delays. A composite controller is then proposed, based on the designed observer, to mitigate the impact of total disturbances. Finally, two illustrative numerical simulations, including a spacecraft close rendezvous and docking scenario and a formation flying scenario, are provided to verify the effectiveness of the proposed ADRC scheme.

Lead Iodide Redistribution Enables In Situ Passivation for Blading Inverted Perovskite Solar Cells with 24.5% Efficiency.

Blade-coating stands out as an alternative for fabricating scalable perovskite solar cells. However, it demands special control of the precursor composition regarding nucleation and crystallization and currently exhibits lower performance than the spin-coating process. It is mainly the resulting film morphology and excess lead iodide (PbI2) distribution that influences the optoelectronic properties. Here, the effectiveness of introducing N-Methyl-2-pyrrolidone (NMP) to regulate the structure of the perovskite layer and the redistribution of PbI2 is found. The introduction of NMP leads to the accumulation of excess PbI2, mainly on the top surface, reducing residual PbI2 at the perovskite buried interface. This not only facilitates the passivation of perovskite grain boundaries but also eliminates the potential degradation of the PbI2 triggered by light illumination in the perovskite buried interface. The optimized NMP-modified inverted perovskite solar cell achieves a champion efficiency of 24.5%, among the highest reported blade-coated perovskite solar cells. Furthermore, 13.68cm2 blading perovskite solar modules are fabricated and demonstrate an efficiency of up to 20.4%. These findings underscore that with proper modulation of precursor composition, blade-coating can be a feasible and superior alternative for manufacturing high-quality perovskite films, paving the way for their large-scale applications in photovoltaic technology.

Intraspecies mitogenomic variation in the Black-throated Tit (Aegithalos concinnus): conserved structure, concerted evolution of duplicate control regions and multiple distinct evolutionary lineages

The mitochondrial genome is a prominent research topic due to its indispensable role in organisms and its application in many research disciplines. However, few studies have investigated intraspecies mitogenomic variation. In this study, 69 mitogenomes of the Black-throated Tit (Aegithalos concinnus) were assembled and annotated from a large number of short reads generated using high-throughput sequencing technology. Comparative analyses revealed that mitogenomic characteristics such as length, gene and nucleotide composition, codon usage, and duplicated control regions were relatively conserved despite substantial intraspecies morphological changes. Yet, all the individuals from the subspecies A. c. iredalei had one more nucleotide in the 12S rRNA than the other studied subspecies. Phylogenetic analyses showed five distinct lineages based on the complete mitogenomes and the 13 combined protein-coding genes, whereas only four lineages were observed when using the duplicate control regions. Most interestingly, each lineage had both copies of the control regions of the comprising individuals, indicating that the paralogous control regions were more similar than the orthologous sequences from the distinct lineages. This suggested the control regions had undergone concerted evolution. The Black-throated Tit has complex evolutionary history and needs further investigating the taxonomic status of these lineages, as well as the underlying evolutionary processes. Our findings call for more research on intraspecies mitogenomic variation.

Minimizing phase delay of feedback control signals for electromagnetic vibrators to reduce measurement uncertainty in ultra-low frequency vibration calibration

Suppressing the distortion of ultra-low frequency (ULF) vibration waveforms produced by an electromagnetic vibrator (EMV) presents significant challenges, leading to considerable measurement uncertainty during vibration calibration. A phase delay minimization method for feedback control signals is proposed to reduce the harmonic distortion of ULF vibration waveforms. The method quantitatively describes the influence law of the active viscoelastic approach on system frequency response characteristics. By selecting appropriate active stiffness and damping coefficients, the method minimizes the phase delay of the feedback control signal, thereby enhancing the disturbance suppression capability of the displacement and velocity composite negative feedback control. Experimental results indicate that harmonic distortion of the vibration waveform is reduced to less than 1.70 % within the ULF frequency range of 0.001 Hz ≤ f ≤ 1 Hz. Furthermore, the amplitude sensitivity calibration uncertainty, which arises from vibration waveform distortion, has been reduced to 0.038 % (k = 1.8), thereby improving the accuracy of vibration calibration.