Structural Control Research Articles

Reinforcement Learning for Integrated Structural Control and Health Monitoring

Reinforcement Learning for Integrated Structural Control and Health Monitoring

Genesis of LCT Pegmatites during Early Paleozoic Orogeny of the North Qinling Orogenic Belt, China: Emplacement Conditions and Structural Control

AbstractThe Guanpo pegmatite field in the North Qinling orogenic belt (NQB), China, hosts the most abundant LCT pegmatites. However, their emplacement conditions and structural control remain unexplored. In this contribution, we investigated it combining pegmatite orientation measurement with oxygen isotope geothermometry and fluid inclusion study. The orientations of type A1 pegmatites (Pf < σ2) are predominantly influenced by P‐ and T‐fractures due to simple shearing in Shiziping dextral thrust shear zone during D2 deformation, whereas type A2 pegmatites (contemporaneous with D4) are governed by hydraulic fractures aligned with S0 and S0+1 stemming from fluid pressure (Pf < σ2). Additionally, type B pegmatites (Pf ≤ σ2) exhibit orientations shaped by en echelon extensional fractures in local ductile shear zones (contemporaneous with D3). The albite‐quartz oxygen isotope geothermometry and microthermometric analysis of fluid inclusions in elbaites from the latest pegmatites (including types B and A2) suggest that the crystallization P‐T for late magmatic and hydrothermal stages are 527.5–559.2°C, 320°C, 3.1–3.6 kbar and 2.0 kbar, respectively. Our observations along with previous studies suggest that the genesis of the LCT pegmatites was a long‐term, multi‐stage event during early Paleozoic orogeny (including the collision stage) of the NQB, and was facilitated by various local fractures.

Application of Geophysical Methods in the Identification of Mineralized Structures and Ranking of Areas for Drilling as Exemplified by Alto Guaporé Orogenic Gold Province

Mineral exploration works conducted in the Alto Guaporé Gold Province (AGGP), situated in the southwest region of the Amazon Craton in Brazil, faces the challenges of many gold provinces around the world, i.e., declines in the discoveries of new economic deposits and increases in exploration costs. Ground geophysical methods, combined with structural analyses and geological mapping, are valuable tools that have potential to improve accuracy in selecting exploration targets and in determining drilling locations. AGGP deposits are primarily associated with regional N20°–W50° inverse faulting and sheared geologic contacts between Meso-Neoproterozoic siliciclastic metasedimentary rocks and Mesoproterozoic basement (granite and volcano–sedimentary sequences). Mining currently occurring in the central portion of the province drives exploration works towards the many existing targets at the area. Among them, the ABP target is one of the most promising for being located few kilometers north of the Pau-a-Pique mine. At the ABP target, gold is associated with hydrothermal alteration located in the sheared contacts and in the hinge zone of folded metasedimentary sequence. Hydrothermal phases include Fe-oxides, sulfide (py), muscovite and quartz veins. In this study, we use magnetic and geoelectric (induced polarization) surveys coupled with structural and geological mapping to identify potential footprints within the ABP target. The results from induced polarization (IP) profiles successfully mapped the shape and orientation of the main structures down to approximately 350 m at the ABP target, indicating potential locations for hydrothermal alteration hosting gold. Additionally, 3D magnetic data inversions illustrated the distribution of magnetic susceptibilities and magnetization vectors associated with shear zone structures and isolated magnetic bodies. Magnetic data highlighted fault zones along the contacts between metamorphic rocks and granites, while IP data identified areas with high chargeability, correlating with sulfidation zones mineralized with gold. These findings suggest a metallogenic model where gold deposits are transported through deep structures connected to regional faults, implying significant tectonic and structural control over gold deposition. The results underscore the potential of multiparameter geophysics in identifying and characterizing deposits in both deep and strike, thereby advancing our understanding of mineral occurrences in the region and enhancing the search for new mineralized zones.

Experimental investigation of the effective parameters on the lead extrusion damper performance

Lead extrusion dampers (LED) are employed for seismic response control of various structures due to their advantages over other energy-dissipative devices. However, a reliable design algorithm and an optimization process are essential to ensure optimal performance within the host structural system. Thus, the influence of device parameters on the damper behavior must be clearly understood. In the first part of this comprehensive study, the effect of different parameters on the LED performance was experimentally investigated. To this end, 23 specimens with different prestressing levels, bulge-to-shaft diameter ratios, shaft-to-bulge transition zone geometries, and device length ratios were cyclically tested under varying displacement amplitudes, i.e., 5 mm, 10 mm, and 20 mm, and loading rates, 0.5 mm/s, 1.0 mm/s, and 2.0 mm/s. Subsequently, they were exposed to a ramp-type loading up to the amplified design displacement. After satisfactorily completing the experimental tests, the behavior of the LEDs was compared in terms of their hysteretic behavior, energy dissipation capacities, temperature change, and stable behavior. It was concluded that the most influential parameters on the LED behavior were the bulge-to-shaft diameter ratio and the prestressing level on the lead. In addition to its effects on improving the hysteretic behavior, having a smooth shaft-to-bulge transition zone geometry was essential to guarantee a stable damper behavior.

Experimental Study on the Longitudinal Motion Performance of a Spherical Robot Rolling on Sandy Terrain

To provide the necessary theoretical models of sphere–soil interaction for the structural design, motion control, and simulation of spherical robots, this paper derives analytical expressions for traction force and driving torque when spherical robots slide and sink into sandy terrain, based on terramechanics and multibody dynamics. Furthermore, orthogonal experimental analysis identifies the load, joint angular acceleration, and maximum joint angular velocity of spherical robots as influencing factors, highlighting that the load significantly affects their longitudinal motion performance. Experimental results indicate that rolling friction and additional resistance on sandy terrain cannot be ignored. The corrected theoretical model effectively replicates the temporal variation of driving torque exerted by spherical robots on sandy terrain. Numerical computations and experimental analyses demonstrate that increasing the radius of the sphere shell, the load, and the slip ratio all lead to increased traction force and driving torque. However, traction force and driving torque begin to decrease once the slip ratio reaches approximately 0.5. Therefore, in the design of spherical robot structures and control laws, appropriate parameters such as load and slip ratio should be chosen based on the established sphere–soil interaction theoretical model to achieve high-quality longitudinal motion performance on sandy terrain.

Based on graph theory, design of distributed control system for multi-quadcopter UAVs

This paper addresses the formation control system for multi-quadcopter UAVs, proposing a control strategy based on finite-time stability theory. It designs position controllers with a dual power structure and attitude controllers combined with non-singular terminal sliding mode to achieve fast convergence and high-precision tracking. Through Lyapunov stability analysis, the paper proves the finite-time convergence of the control strategy. Simulation experiments validate the method's excellent performance in formation establishment, maintenance, and complex trajectory tracking, demonstrating rapid convergence, high precision, and strong disturbance rejection capabilities. This research provides theoretical and technical support for cooperative control of multi-quadcopters.

Solvent Effect for the Structural Control of Molecular Architectures Consisting of Trinuclear Ruthenium Clusters and Ligands at the HOPG Surface.

The molecular architecture of a triruthenium complex and 1,4-di(4-pyridyl)benzene on highly oriented pyrolytic graphite was investigated by drop-casting mixed tetrahydrofuran and methanol solutions. Atomic force microscopy revealed the formation of one-dimensional molecular wires on highly oriented pyrolytic graphite after heating the mixed tetrahydrofuran solution, whereas large ring structures were formed in the methanolic solution. It was found that the molecular architectures composed of triruthenium complexes and 1,4-di(4-pyridyl)benzene strongly depend not only on the temperature of the solution but also on the organic solvents. The formation of the molecular architecture was supported by the ultraviolet-visible absorption spectra of the mixed solution and the electrochemical responses of the deposited film.

Concept, optimization and performance evaluation of a novel particle tuned inertial damper (PTID)

Developing more effective vibration control systems is a hot topic in the field of structural vibration control. In the past decades, many types of control systems have been developed, including the well-known particle dampers (PDs). However, the widespread applications of particle dampers are still limited due to some inherent issues: namely large secondary mass and low capacity of energy dissipation in some cases. To address the above issues, a novel particle tuned inertial damper (PTID) is proposed based on the concept of inerter. In particular, the configuration and working mechanism of PTID are first introduced, and a multi-objective optimization framework is formulated by concurrently minimizing both the displacement and acceleration responses. Subsequently, the seismic control effectiveness of PTID is demonstrated by using a single-degree-of-freedom (SDOF) system, and parametric studies are performed to investigate the influences of the preassigned particle mass ratio, inertance-to-mass ratio and amplification factor on the optimal parameters and control performance of PTID. Finally, case studies are performed to further illustrate the control effectiveness of PTID in the seismic protection of a three-story structure. The results demonstrate that, compared to the traditional PD, the proposed PTID could more effectively suppress both the displacement and acceleration responses by utilizing a much smaller particle mass ratio; and increasing the particle mass ratio and amplification factor can enhance the control effectiveness of PTID.

Optimal design of fractional-order proportional integral derivative controllers for structural vibration suppression

In designing control systems, it is known that fractional-order proportional integral derivative (FOPID) controllers often provide greater flexibility than conventional proportional integral derivative (PID) controllers. This higher level of flexibility has proven to be extremely valuable for various applications such as vibration suppression in structural engineering. In this paper, we study the optimization of FOPID controllers using twelve well-established algorithms to minimize structural responses under seismic excitations. The algorithms include crystal structure algorithm (CryStAl), stochastic paint optimizer, particle swarm optimization, krill herd, harmony search, ant colony optimization, genetic algorithm, grey wolf optimizer, Harris hawks optimization, sparrow search algorithm, hippopotamus optimization algorithm, and duck swarm algorithm. In addition to highlighting the benefits of fractional calculus in structural control, this study provides a detailed analysis of FOPID controllers as well as a brief description of the algorithms used to optimize them. To evaluate the efficiency of the proposed techniques, two building models with different numbers of stories are examined. FOPID controllers are designed based on oustaloup’s approximation and the El Centro earthquake data. Using five well-known metrics, the performances of the developed methods are evaluated against five earthquake scenarios, including the recent earthquake in Turkey. A non-parametric (Friedman) test is also employed to compare the algorithms based on their corresponding vibration reduction. The findings of this analysis show that CryStAl consistently performs better than the other algorithms for both building models, thus resulting in superior vibration suppression.

Optimized PI-PDF active structural acoustic control of smart FG GPL-reinforced closed-cell metallic foam sandwich plate

This study investigates Active Structural Acoustic Control (ASAC) applied to sandwich plates featuring Functionally Grade (FG) porous Graphene-Platelet-Reinforced Piezoelectric (GPLRP) materials. These plates incorporate a core layer with internal pores and GPLs dispersed in a metal matrix, along with piezoelectric sensors and actuators. Using a spatial state-space formulation based on linear 3D piezoelasticity theory, a semi-analytical solution is derived for the vibroacoustic response of these sandwich plates. The mechanical properties of the porous core are modeled using a closed-cell metal foam. The effects of various parameters, including porosity distributions, porosity coefficient, weight fractions of nanofiller, and geometric parameters on the radiation efficiency and radiated sound power have been investigated. Then, the validation of the proposed model is examined by comparing the natural frequencies calculated in the present study to those from the literature. This comparison allows us to assess the accuracy and reliability of our model against established findings. Radiated sound power reduction from mechanically excited structures is achieved by employing a dual-stage Proportional Integral–Proportional Derivative with Filter (PI-PDF) controller, optimized using Grey Wolf Optimization (GWO). Finally, several numerical simulations are conducted to validate the effectiveness and accuracy of the proposed active control strategy.

A piezoelectric and electromagnetic vibration energy harvesting system based on spring pendulum structure and MPPT control

A piezoelectric and electromagnetic vibration energy harvesting system based on spring pendulum structure and MPPT control

Tools for Multiplexed Imaging and Control of Biological Structure and Function

Tools for Multiplexed Imaging and Control of Biological Structure and Function

Vibration control of structure using active tuned mass damper: A new control algorithm

This paper investigates the vibration behavior of a 10-story benchmark building controlled with an active tuned mass damper (ATMD) under earthquake loads. An ATMD, typically installed on the top floor, is a modified form of a tuned mass damper (TMD) that includes a mass, spring, damper, and an actuator enhancing system performance and structural damping. The force and movement direction of the ATMD are controlled by a processor and actuator. In the ATMD system, control algorithms determine the magnitude and direction of the applied force. This research introduces a new control algorithm based on the structure’s dynamic response and ATMD stiffness. To evaluate the performance of this algorithm, linear–quadratic regulator (LQR) and fuzzy logic controller (FLC) algorithms were designed and presented for comparison. The results indicate that the proposed algorithm outperformed the other algorithms, reducing the structure’s displacement and acceleration responses by an average of 40% and 28.16%, respectively, compared to the uncontrolled state.

Magnetically Driven Cactus Spinelike Superhydrophobic Fe3O4 Vertical Array for High-Performance Fog Harvesting.

Cactus spinelike materials have attracted much attention due to high fog harvesting efficiency, but great challenges in structure fabrication and structural controllability still remain. In this study, we proposed a magnetically driven spray-coating method to fabricate a cactus spinelike superhydrophobic Fe3O4 vertical array on nonwoven cotton fabric. This method is simple and controllable; a mixture containing magnetic Fe3O4 particles and organosilicon resin was atomized into tiny droplets and arranged along the magnetic field lines. Different from the traditional method to prepare a cactus spinelike structure via liquid flow under magnet, which is usually accompanied with a big structure size and an unobvious structure feature due to the high viscosity of magnetic liquid. However, if the magnetic liquid is transformed into tiny magnetic droplets by a spraying method, it is promising to prepare micrometer-scale conical structures, and the reduction degree of bionic structures is high. When the fabricated structure is used for fog harvesting, it shows an extremely high efficiency of approximately 6.33 g cm-2 h-1, which is superior to most state-of-the-art fog harvesting materials. Considering the advantages of simplicity, structure controllability, and high fog harvesting rate, the reported strategy provides an avenue to build up high-performance fog harvesting materials.

Metal-organic framework derived crystalline nanocarbon for Fenton-like reaction

Nanoporous carbons with tailorable nanoscale texture and long-range ordered structure are promising candidates for energy, environmental and catalytic applications, while the current synthetic methods do not allow elaborate control of local structure. Here we report a salt-assisted strategy to obtain crystalline nanocarbon from direct carbonization of metal-organic frameworks (MOFs). The crystalline product maintains a highly ordered two-dimensional (2D) stacking mode and substantially differs from the traditional weakly ordered patterns of nanoporous carbons upon high-temperature pyrolysis. The MOF-derived crystalline nanocarbon (MCC) comes with a high level of nitrogen and oxygen terminating the 2D layers and shows an impressive performance as a carbocatalyst in Fenton-like reaction for water purification. The successful preparation of MCC illustrates the possibility to discover other crystalline heteroatom-doped carbon phases starting from correctly designed organic precursors and appropriate templating reactions.

Bioinspired Three-Component System to Prepare Full-Color Functional Biomimetic Pigments.

Nature provides a great source of inspiration for the development of sustainable materials with excellent properties, among which melanin with optical, electronic, and radiation protection properties are considered to be promising coloring materials. However, compared to chemical pigments, the single color, complex oxidation process, and poor solubility of natural melanin strongly limit their further applications. Here, we introduce a series of melanin-like polymeric pigments with amino acid-encoded physicochemical properties by a simple three-component reaction system. Our protocol enables artificial control of the chromophore structures through the rational design of the substrates and dopants, thereby combining the safety and functionality of biopigments with the color richness of chemical dyes. Similar to the photoprotective effect of natural melanin, the polymeric pigments showed excellent antioxidant activity in reducing free radicals and have the advantages of iridescent color, strong tinting strength, stability, and affordability. Furthermore, due to their ability to dye substrates, these biomimetic are expected to become new low-cost bioactive chromophores and find various biochemical applications such as in clothing and hair dyeing, food addition, and anticounterfeiting detection.

Investigation of a newly developed shear built-in valve type MR damper with high damping: Theories and experiments

Magnetorheological (MR) dampers are widely used as semi-active energy-dissipation devices in structural vibration control. Traditional MR dampers, particularly their working mode, often struggle to achieve a high damping force output and sometimes fail to meet the needs of practical engineering. Therefore, it is necessary to study MR dampers that can provide a high damping force. This study proposes an MR damper that combines a built-in shear valve with various working modes of shear extrusion. The damper generates a higher damping force by applying a current to the coils at different positions and altering its working mode. First, the ANSYS Maxwell software simulates the internal magnetic circuit of the damper to assess whether the magnetic field intensity distribution and circuit direction meet the design requirements. Analysis revealed that the internal magnetic circuit distribution was reasonable and satisfied the operating requirements of the damper. Furthermore, the mechanical models of the two working modes were derived based on the Bingham and double-viscous models. Finally, the accuracies of the mechanical models were verified experimentally. The experimental results showed that the simulation values closely matched the experimental values under all the working conditions. Therefore, the proposed mechanical models are reasonable, and can provide significant reference values for practical engineering applications.

Characterization and Mechanism Elucidation of Nano-TiO2 Composites Prepared by Gaseous Detonation Method.

In this study, a series of nano-TiO2 composite materials, including nano-TiO2, nano-SnO2/TiO2, nano-SiO2/TiO2, and nano-Fe2O3/TiO2, were successfully synthesized via the gaseous detonation method. Comprehensive characterization of the synthesized samples was carried out through X-ray diffraction (XRD), transmission electron microscopy/high-resolution TEM (TEM/HRTEM), scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDS), Brunauer-Emmett-Teller (BET) method, and Fourier transform infrared (FTIR) analysis, which unveiled the significant influence of precursor types on the microstructure of the composite materials. Specifically, the incorporation of Sn4+ promoted the transformation of TiO2 to the rutile phase, reducing particle sizes from 25 to 19 nm and increasing the specific surface area from 44 to 86 m2/g. In contrast, the introduction of SiO2 impeded the rutile phase formation, leading to a marked reduction in particle size to 14 nm and an enhancement of the specific surface area to 104 m2/g. Furthermore, the presence of Fe3+ promoted the formation of the rutile phase and enabled particle growth to 44 nm. These findings not only deepen the understanding of structural control in the synthesis of nano-TiO2 composite materials via the gaseous detonation method but also highlight the critical role of precursor selection in determining the properties of the resulting materials.

CaLi2PN3 - A Quaternary Chain-Type Nitridophosphate by Medium-Pressure Synthesis.

Nitridophosphates are in the focus of current research interest due to their structural versatility and properties, such as ion conductivity, ultra-incompressibility and luminescent properties when doped with suitable activator ions. Multinary representatives often require thorough investigation due to the competition with the thermodynamically more stable binary and ternary compounds. Another point of concern is the synthetic control of structural details, which is usually limited by conventional bottom-up syntheses. In this study, we report on the synthesis and characterization of the quaternary nitridophosphate CaLi2PN3. Various synthesis protocols were used for the preparation of CaLi2PN3, including the novel nitridophosphate double salt approach. The crystal structure was solved and refined from single-crystal X-ray diffraction data and confirmed by Rietveld refinement, solid-state NMR spectroscopy, EDX measurements and low-cost crystallographic calculations. The experimental results were corroborated by DFT calculations, which revealed the electronic band structure. Formation energy calculations allowed conclusions to be drawn about the stability in comparison to the initial ternary nitridophosphates. The synthesis of CaLi2PN3 exemplifies the enormous potential of medium-pressure syntheses in the field of nitridophosphate research. Furthermore, the presented new synthesis route allows a certain degree of structural control, which is a promising addition to previous synthesis strategies in nitridophosphate chemistry.

Vibration control and robustness analysis of tensegrity structures via fuzzy dynamic sliding mode control method

This study addresses the problem of mitigating vibration responses in tensegrity structures subjected to complex dynamic loading conditions. The overall purpose is to develop an effective control method to enhance the stability and performance of these structures. To achieve this, a fuzzy dynamic sliding mode control (FDSMC) method is proposed. The methodology involves deriving the state space expression of the controlled system based on the tensegrity structure's dynamic model, followed by designing a dynamic sliding mode controller using the reaching law. Fuzzy rules are incorporated to adaptively adjust the dynamic sliding mode parameters, accounting for uncertainties in controller parameters, thereby ensuring high efficiency and smooth controller output. A comparative analysis scheme, focusing on identical energy input on actuators, is utilized to evaluate the performance of various active vibration control methods. Two illustrative examples, a spatial double-layer tensegrity beam and a complex tensegrity spiral tower, are investigated in detail. The findings demonstrate that the FDSMC method significantly reduces structural dynamic responses and improves algorithm robustness compared to the conventional linear quadratic regulator (LQR) method, indicating its promising potential for relevant engineering applications.