AI-supported, feedback-regulated ultrasonic anchoring system for nanoparticle anchoring

Abstract

An AI-supported, feedback-regulated ultrasonic anchoring system for the self-regulating ultrasonic anchoring of nanoparticles on polymer-carbon nanocomposites, comprising: a reaction chamber designed to hold a mixture of a polymer, a carbon material and nanoparticles; an ultrasound generator integrated into the reaction chamber, configured to expose the mixture to ultrasound irradiation; at least one sensor that is operationally connected to the ultrasound generator and is configured to continuously measure at least one system response parameter in situ during ultrasound irradiation, wherein the system response parameter changes depending on the anchoring of the nanoparticles on the polymer-carbon framework, and wherein the sensor is further configured to transmit the measured data of the system response parameter in real time; a control unit configured to receive and evaluate the system response parameter measured by the sensor, the control unit further being configured to automatically terminate or modulate the ultrasonic irradiation upon detection of the stabilized or saturated state; and a feedback control module operationally connected to the control unit, configured to detect when the system response parameter reaches a stabilized or saturated state within a predefined tolerance range, whereby the duration of the ultrasonic irradiation is determined exclusively by the measured system response parameter and not by a predetermined sonication time.

Description

AREA OF INVENTION

[0001] The present disclosure relates to polymer-carbon nanocomposites and in particular to an AI-supported, feedback-controlled ultrasonic system for anchoring nanoparticles on a polymer-carbon scaffold based on real-time system response monitoring instead of a predetermined sonication time. BACKGROUND OF THE INVENTION

[0002] Polymer-carbon nanocomposites with anchored nanoparticles have garnered significant attention due to their enhanced electrical, mechanical, and functional properties. Ultrasound is frequently employed to disperse and anchor nanoparticles onto polymer-carbon matrices, enabling uniform distribution and strong interfacial bonding. However, conventional ultrasonic methods operate with fixed parameters such as constant output power or predefined irradiation time, without considering the actual progress of nanoparticle anchoring.

[0003] Such open-loop processes have serious limitations, including polymer degradation due to excessive sonication, incomplete nanoparticle anchoring due to inadequate treatment, low reproducibility between different batches, and excessive energy consumption. The inability to monitor and react to system behavior in real time leads to unpredictable material properties and inefficient processing. These challenges are particularly evident in industrial production, where process variations can significantly impact product quality and manufacturing costs.

[0004] Therefore, there is a need for a self-regulating ultrasonic anchoring system that can determine anchoring completion based on the actual system behavior on-site, rather than arbitrary time-based protocols. Such a system would enable adaptive control, prevent under- and overtreatment, improve reproducibility, and optimize energy efficiency, while simultaneously ensuring consistent nanocomposite quality. SUMMARY OF THE INVENTION

[0005] The present disclosure relates to an AI-supported, feedback-controlled ultrasonic anchoring system. The invention provides such a system in which nanoparticles are anchored to a polymer-carbon scaffold by means of ultrasonic irradiation controlled exclusively by real-time system response parameters. During the ultrasonic treatment, at least one system response parameter is continuously monitored. The ultrasonic irradiation is automatically terminated or modulated as soon as stabilization or saturation of the monitored parameter is detected, indicating the completion of the nanoparticle anchoring. The feedback control is supported by an AI or machine learning module that analyzes real-time sensor data and dynamically optimizes the ultrasonic parameters. The duration of the ultrasonic irradiation is not predefined but is determined exclusively by the monitored system response.

[0006] The present disclosure relates to an AI-supported, feedback-controlled ultrasonic anchoring system. The system comprises: a reaction chamber for receiving a mixture of polymer, carbon material, and nanoparticles; an ultrasonic generator integrated into the reaction chamber for sonicating the mixture; at least one sensor connected to the ultrasonic generator for continuously measuring at least one system response parameter during ultrasonic irradiation, wherein this parameter changes depending on the anchoring of the nanoparticles to the polymer-carbon framework; wherein the sensor transmits the measurement data of the system response parameter in real time; a control unit for receiving and evaluating the system response parameters measured by the sensor and for automatically terminating or modulating the ultrasonic irradiation after reaching a stabilized or saturated state.and a feedback control module operationally connected to the control unit, configured to detect when the system response parameter reaches a stabilized or saturated state within a predefined tolerance range, whereby the duration of the ultrasonic irradiation is determined exclusively by the measured system response parameter and not by a predetermined sonication time.

[0007] The purpose of this disclosure is to provide an AI-supported, feedback-controlled ultrasonic anchoring system.

[0008] Another objective of the present disclosure is to provide a self-regulating ultrasonic anchoring system for polymer-carbon nanocomposites that determines the anchoring closure based on the in-situ system behavior and not on predefined time-based protocols.

[0009] Another objective of the present disclosure is to enable adaptive control of the ultrasonic operating parameters in real time in order to achieve uniform anchoring of the nanoparticles and reproducible properties of the nanocomposite across different batches.

[0010] Another objective of the present disclosure is to prevent polymer degradation and structural damage in the polymer-carbon matrix by dynamically limiting ultrasound exposure to the minimum required for effective nanoparticle anchoring.

[0011] Another objective of the present disclosure is to reduce the occurrence of incomplete nanoparticle anchoring by automatically extending or intensifying the ultrasound treatment when in-situ indicators show insufficient anchoring progress.

[0012] Another objective of the present disclosure is to improve batch-to-batch reproducibility in the industrial production of polymer-carbon nanocomposites by maintaining controlled and repeatable ultrasonic anchoring conditions controlled by feedback signals.

[0013] Another objective of the present disclosure is to optimize the energy efficiency of the ultrasonic anchoring process by terminating or reducing the ultrasonic irradiation once a criterion indicating the completion of the anchoring has been met.

[0014] Another objective of the present disclosure is to provide a monitoring and control system capable of correlating ultrasonic response signals in real time with the degree of nanoparticle anchoring in order to ensure consistent quality of the nanocomposite.

[0015] However, another objective of the present disclosure is to facilitate the scalable implementation of the ultrasonic anchoring method in industrial environments while minimizing process variability, production costs and quality-related reject rates.

[0016] To further clarify the advantages and features of the present disclosure, the invention is described in more detail with reference to specific embodiments illustrated in the accompanying drawing. It is understood that this drawing merely shows typical embodiments of the invention and is therefore not to be understood as limiting its scope of protection. The invention is described and explained in more detail and with reference to the accompanying drawing. BRIEF DESCRIPTION OF THE IMAGE

[0017] These and other features, aspects and advantages of the present disclosure will be better understood when the following detailed description is read with reference to the accompanying drawing, in which the same symbols represent the same parts, wherein: Fig. Figure 1 shows a block diagram of an AI-supported, feedback-controlled ultrasonic anchoring system according to an embodiment of the present disclosure.

[0018] Furthermore, those skilled in the art will recognize that the elements in the drawing are simplified and not necessarily drawn to scale. For example, the flowcharts illustrate the process by highlighting the main steps to facilitate understanding of the present disclosure. With regard to the construction of the device, one or more components may be represented in the drawing by conventional symbols. The drawing may show only those specific details relevant to understanding the embodiments of the present disclosure, so as not to clutter the drawing with details that are already apparent to those skilled in the art from the description contained herein. DETAILED DESCRIPTION:

[0019] To facilitate understanding of the principles of the invention, reference is made below to the embodiment shown in the drawing, which is described using specific terms. It is understood, however, that this does not limit the scope of protection of the invention. Rather, modifications and further developments of the depicted system, as well as further applications of the inventive principles shown therein, are conceivable, insofar as they would normally occur to a person skilled in the art in the field of the invention.

[0020] It will be clear to those skilled in the art that the foregoing general description and the following detailed description are exemplary and explanatory of the invention and are not to be understood as a limitation thereof.

[0021] References to “an aspect”, “another aspect”, or similar phrases in this description mean that a particular feature, structure, or property described in connection with the embodiment is included in at least one embodiment of the present disclosure. Therefore, phrases such as “in one embodiment”, “in another embodiment”, and similar expressions in this description may, but do not necessarily, all refer to the same embodiment.

[0022] The terms "includes," "comprehensive," or similar expressions denote non-exclusive inclusion. Thus, a procedure or method containing a list of steps does not only include those steps but may also include further steps not explicitly listed or inherent in the procedure or method. Likewise, the statement "includes..." for one or more devices, subsystems, elements, structures, or components, without further limitations, does not preclude the existence of other devices, subsystems, elements, structures, or components.

[0023] Unless otherwise defined, all technical and scientific terms used herein have the same meanings generally known to those skilled in the art in the field to which this invention belongs. The systems, methods, and examples described herein serve only for illustration and are not to be understood as limiting.

[0024] Embodiments of the present disclosure are described in detail below with reference to the attached drawing.

[0025] The functional units described in this specification are referred to as devices. A device may be implemented in programmable hardware such as processors, digital signal processors, central processing units, FPGAs, PALs, PLDs, cloud processing systems, or similar. Devices may also be implemented in software for execution by various processor types. An identified device may contain executable code and, for example, comprise one or more physical or logical blocks of computer instructions, which may be organized as an object, procedure, function, or other construct. However, the executable files of an identified device need not be physically related; they may consist of different instructions stored in different locations that, when logically combined, constitute the device and fulfill its purpose.

[0026] The executable code of a device or module can consist of a single instruction or multiple instructions and can even extend across different code sections, applications, and storage media. Similarly, operational data within the device can be identified and represented, and can exist in any suitable form and be organized in any data structure. The operational data can be captured as a single data record or distributed across various storage media and may exist, at least partially, as electronic signals within a system or network.

[0027] References to “a selected embodiment”, “an embodiment”, or “an embodiment” in this description mean that a particular feature, structure, or property described in connection with the embodiment is included in at least one embodiment of the disclosed subject matter. Therefore, the phrases “a selected embodiment”, “in an embodiment”, or “in an embodiment” appearing at different points in this description do not necessarily refer to the same embodiment.

[0028] Furthermore, the described features, structures, or properties can be combined in one or more embodiments in any suitable manner. The following description contains numerous specific details to enable a comprehensive understanding of the embodiments of the disclosed subject matter. However, a person skilled in the art will recognize that the disclosed subject matter can also be realized without one or more of the specific details or with other methods, components, materials, etc. In other cases, known structures, materials, or processes are not presented or described in detail so as not to obscure aspects of the disclosed subject matter.

[0029] According to the exemplary embodiments, the disclosed computer programs or modules can be executed in a variety of ways, for example, as an application running in the memory of a device or as a hosted application running on a server and communicating with the device application or browser via various standard protocols such as TCP / IP, HTTP, XML, SOAP, REST, JSON, and other suitable protocols. The disclosed computer programs can be written in programming languages ​​that run either in the device's memory or on a hosted server, such as BASIC, COBOL, C, C++, Java, Pascal, or scripting languages ​​such as JavaScript, Python, Ruby, PHP, Perl, or other suitable programming languages.

[0030] Some of the described embodiments involve data transmission over a network, such as the transmission of various inputs or files. The network may include, for example, the internet, wide area networks (WANs), local area networks (LANs), analog or digital wired and wireless telephone networks (e.g., PSTN, ISDN, cellular networks, and xDSL), radio, television, cable, satellite, and / or other transmission or tunneling mechanisms for data. It may include multiple networks or subnetworks, each of which may, for example, have a wired or wireless data path. The network may include a circuit-switched voice network, a packet-switched data network, or another network for transmitting electronic data. For example, it may be based on the Internet Protocol (IP) or Asynchronous Transfer Mode (ATM) and support voice communication using VoIP, Voice over ATM, or similar protocols.In one embodiment, the network comprises a mobile network configured for the exchange of text or SMS messages.

[0031] Examples of networks include Personal Area Networks (PAN), Storage Area Networks (SAN), Home Area Networks (HAN), Campus Area Networks (CAN), Local Area Networks (LAN), Wide Area Networks (WAN), Metropolitan Area Networks (MAN), Virtual Private Networks (VPN), Enterprise Private Networks (EPN), the Internet, Global Area Networks (GAN), and so on.

[0032] Fig. Figure 1 shows a block diagram of an AI-supported, feedback-controlled ultrasonic anchoring system according to an embodiment of the present disclosure.

[0033] In relation to Fig.1 comprises the AI-supported, feedback-controlled ultrasonic anchoring system (100): a reaction chamber (102) for receiving a mixture of polymer, carbon material and nanoparticles; an ultrasonic generator (104) integrated into the reaction chamber (102) for sonicating the mixture with ultrasound; at least one sensor (106) connected to the ultrasonic generator (104) which continuously measures at least one system response parameter during ultrasonic irradiation, which changes depending on the anchoring of the nanoparticles to the polymer-carbon framework; the sensor (106) transmits the measurement data of the system response parameter in real time; a control unit (108) receives and evaluates the system response parameters measured by the sensor (106) and automatically terminates or modulates the ultrasonic irradiation after reaching the stabilized or saturated state.and a feedback control module (110) that is operationally connected to the control unit (108) and is configured to detect when the system response parameter reaches a stabilized or saturated state within a predefined tolerance range, wherein the duration of the ultrasonic irradiation is determined exclusively by the measured system response parameter and not by a predetermined sonication time.

[0034] In one embodiment, the ultrasound generator (104) is configured to operate in a frequency range of approximately 15 kHz to 60 kHz. The ultrasound generator (104) has adjustable power levels and optionally a pulse modulation capability.

[0035] In one embodiment, the at least one sensor (106) is configured to measure electrical conductivity or electrical impedance as a system response parameter. The feedback control module (110) is configured to detect stabilization when the change in electrical conductivity or electrical impedance remains within a defined percentage range over a continuous monitoring interval. The sensor (106) is further configured to measure at least one of the following quantities: optical absorption, turbidity, magnetic response, pH change, or ionic conductivity. The defined percentage range is between ±1% and ±10%. The continuous monitoring interval is a predefined period during which the change in electrical conductivity or electrical impedance must remain within the defined percentage range for stabilization to be detected.

[0036] In one embodiment, the system (100) further comprises: an artificial intelligence module (112) in conjunction with the feedback control module (110) and the control unit (108), wherein the artificial intelligence module (112) is configured to receive the measured system response parameter from the sensor (106) and analyzes temporal trends of the system response parameter, whereupon the artificial intelligence module (112) predicts the completion of the nanoparticle anchoring, wherein the artificial intelligence module (112) is further configured to dynamically optimize at least one ultrasound parameter selected from the ultrasound power, ultrasound frequency and duty cycle of the ultrasound generator.

[0037] In one embodiment, the control unit (108) is further configured to modulate the ultrasound irradiation by adjusting at least one of the following parameters: ultrasound output power, ultrasound frequency, pulse duration and pulse interval; the modulation is based on the rate of change of the system response parameter as evaluated by the feedback control module (110) using the artificial intelligence module (112).

[0038] In one embodiment, the artificial intelligence module (112) comprises a trained model configured to: receive historical data of system response parameters from previous anchoring operations; identify patterns that correlate the behavior of the system response parameters with the completion of the nanoparticle anchoring; and generate optimized ultrasonic parameter settings for the control unit (108) based on a real-time comparison of the current system response parameter data with the identified patterns.

[0039] In one embodiment, the system (100) further comprises: a data storage module (114) configured to store the system response parameter data measured during ultrasonic irradiation, wherein an output terminal of the sensor (106) is connected to the control unit (108) and the data storage module (114).

[0040] In one embodiment, the system (100) further comprises: a display module (116) in conjunction with the data storage module (114) and the control unit (108), wherein the display module (116) is configured to provide a real-time visualization of the system response parameters and the stabilization status, and wherein the control unit (108) is connected to the display module (116) to display the status of the anchoring process and completion indicators.

[0041] The present invention relates to a system for the feedback-controlled ultrasonic anchoring of nanoparticles onto a polymer-carbon framework. The system comprises an ultrasonic generator, a reaction chamber, at least one sensor for continuous in-situ monitoring, a control unit, and a feedback module. During operation, the sensor continuously measures system response parameters that change depending on the nanoparticle anchoring, such as electrical conductivity or impedance. The control unit evaluates these parameters in real time and automatically terminates or modifies the ultrasonic irradiation as soon as stabilization within a predefined tolerance range is detected.In preferred embodiments, an artificial intelligence or machine learning module supports the analysis of temporal trends, the prediction of anchorage closure, and the dynamic optimization of ultrasonic parameters, including power, frequency, and duty cycle. The duration of ultrasonic irradiation is determined solely by the measured system response and not by a predetermined time. This ensures adaptive processing, avoidance of over- and under-sonication, improved reproducibility, reduced energy consumption, and optimized material performance suitable for industrial production.

[0042] In one embodiment, the polymer comprises at least one of the following materials: conductive polymers, thermoplastics, thermosets, biopolymers, polyaniline, polyvinyl alcohol, or polypyrrole; the carbon material comprises at least one of the following materials: carbon nanotubes, graphene, graphene oxide, reduced graphene oxide, or combinations thereof; and the nanoparticles comprise at least one of the following materials: metal nanoparticles, metal oxide nanoparticles, magnetic nanoparticles, semiconductor nanoparticles, or hybrid nanoparticles. The ultrasonic system comprises a probe or bath ultrasonic generator operating at a frequency of approximately 15–60 kHz and featuring adjustable power and optional pulse modulation. For control purposes, one or more sensors continuously monitor at least one system response parameter during ultrasonic irradiation.A control unit evaluates the parameter in real time and terminates or modifies the ultrasonic irradiation as soon as stabilization within a predefined tolerance range is detected. An AI or ML module supports the control unit by analyzing temporal trends of the monitored parameter, predicting the completion of anchoring, and dynamically optimizing ultrasonic power, frequency, or duty cycle. The system response parameter changes as a direct consequence of nanoparticle anchoring. Preferred parameters include electrical conductivity or electrical impedance stabilization. Alternative parameters include optical absorption or turbidity, magnetic response, pH change, or ionic conductivity.

[0043] The system operates by irradiating a mixture of a polymer, a carbon material, and nanoparticles with ultrasound in a reaction chamber. During the ultrasonic irradiation, at least one sensor continuously measures at least one system reaction parameter, which changes depending on the deposition of the nanoparticles onto the polymer-carbon backbone. The control unit automatically evaluates the measured value of the system reaction parameter received from the sensor in real time. As soon as the system reaction parameter reaches a stable or saturated state within a predefined tolerance range, the control unit activates the ultrasonic generator to terminate or adjust the ultrasonic irradiation. The duration of the ultrasonic irradiation is determined solely by the measured system reaction parameter and not by a predetermined sonication time.This ensures that the deposition process is completed based on the actual physical and chemical changes in the system and not through arbitrary time settings.

[0044] In preferred embodiments, the system response parameter comprises the electrical conductivity or electrical impedance, which directly indicates the degree of nanoparticle anchoring and dispersion within the polymer-carbon matrix. Stabilization of these electrical properties signals the completion of nanoparticle integration into the scaffold. Stabilization is defined as a variation within ±1–10% over a continuous monitoring interval and thus provides a quantitative criterion for process completion. Evaluation of the system response parameter is supported by an artificial intelligence or machine learning module that optimizes ultrasonic parameters in real time, analyzes the temporal evolution of the measured parameters, and predicts the optimal time for process termination or parameter adjustment.The system is capable of producing polymer-carbon nanocomposites with superior and reproducible properties through this feedback-controlled anchoring process.

[0045] The system offers several key advantages over conventional ultrasonic anchoring methods. Real-time, in-situ anchoring control enables continuous monitoring and adaptive adjustment of the ultrasonic process based on actual system behavior. Over- and under-sonication are avoided by automatically terminating or adjusting the ultrasonic irradiation once parameter stabilization is achieved. This prevents polymer degradation due to overtreatment and incomplete anchoring due to undertreatment. AI-powered adaptive optimization dynamically adjusts the ultrasonic parameters to achieve optimal anchoring conditions for each specific material composition and processing batch. Improved reproducibility and material performance result from consistent endpoint determination based on the actual system response, rather than arbitrary time-based protocols.This ensures consistent nanocomposite properties across different production runs. Reduced energy consumption is achieved by precisely terminating the ultrasonic irradiation after anchoring is complete, thus avoiding unnecessary energy waste. Industrial scalability and automation compatibility are enabled by the fully automated feedback control system, which requires no manual intervention or subjective assessments. This makes the system suitable for large-scale production environments.

[0046] The drawing and the preceding description illustrate embodiments. Those skilled in the art will recognize that one or more of the described elements can be combined to form a single functional element. Alternatively, certain elements can be divided into several functional elements. Elements of one embodiment can be added to another. For example, the process flows described here can be modified and are not limited to the manner described herein. Furthermore, the actions of a flowchart need not be performed in the sequence shown; nor do all actions necessarily need to be carried out. Actions that do not depend on other actions can be performed in parallel with the other actions. The scope of protection of the embodiments is in no way limited by these specific examples. Numerous variations, whether explicitly stated in the description or not, such as...Differences in structure, dimensions, and materials are possible. The scope of protection of the embodiments is at least as comprehensive as described by the following claims.

[0047] The advantages, other benefits, and problem solutions have been described above with reference to specific embodiments. However, the advantages, benefits, problem solutions, and any components that can effect or enhance an advantage, benefit, or solution are not to be construed as critical, necessary, or essential features or components of the claims. REFERENCES 100 An AI-supported, feedback-controlled ultrasonic anchoring system. 102 Reaction chamber 104 Ultrasonic generator 106 At least one sensor 108 Control unit 110 Feedback control module 112 Module for Artificial Intelligence 114 Data storage module 116 Display module

Claims

[1] An AI-supported, feedback-regulated ultrasonic anchoring system for the self-regulating ultrasonic anchoring of nanoparticles on polymer-carbon nanocomposites, comprising: a reaction chamber designed to hold a mixture of a polymer, a carbon material and nanoparticles; an ultrasonic generator integrated into the reaction chamber, configured to expose the mixture to ultrasonic irradiation; at least one sensor that is operationally connected to the ultrasound generator and is configured to continuously measure at least one system response parameter in situ during ultrasound irradiation, wherein the system response parameter changes depending on the anchoring of the nanoparticles on the polymer-carbon framework, and wherein the sensor is further configured to transmit the measured data of the system response parameter in real time; a control unit configured to receive and evaluate the system response parameter measured by the sensor, the control unit further being configured to automatically terminate or modulate the ultrasonic irradiation upon detection of the stabilized or saturated state; and a feedback control module operationally connected to the control unit, configured to detect when the system response parameter reaches a stabilized or saturated state within a predefined tolerance range, whereby the duration of the ultrasonic irradiation is determined exclusively by the measured system response parameter and not by a predetermined sonication time. [2] System according to claim 1, wherein the ultrasound generator is designed for a frequency range of about 15 kHz to 60 kHz and has adjustable power levels and optionally pulse modulation capability. [3] System according to claim 1, wherein the at least one sensor is configured to measure electrical conductivity or electrical impedance as a system response parameter, wherein the feedback control module is configured to detect stabilization when the change in electrical conductivity or electrical impedance remains within a defined percentage range over a continuous monitoring interval, and wherein the sensor is further configured to measure at least one of the following quantities: optical absorption, turbidity, magnetic response, pH change or ionic conductivity, wherein the defined percentage range is between plus / minus one percent and plus / minus ten percent;and the continuous monitoring interval is a predefined period during which the change in electrical conductivity or electrical impedance must remain within the defined percentage range for stabilization to be detected. [4] System according to claim 1, further comprising: an artificial intelligence module in conjunction with the feedback control module and the control unit, wherein the artificial intelligence module is configured to receive the measured system response parameter from the sensor and analyzes temporal trends of the system response parameter, on the basis of which the artificial intelligence module predicts the completion of the nanoparticle anchoring, wherein the artificial intelligence module is further configured to dynamically optimize at least one ultrasound parameter selected from the ultrasound power, ultrasound frequency and duty cycle of the ultrasound generator. [5] System according to claim 1, wherein the control unit is further configured to modulate the ultrasound irradiation by adjusting at least one of the following parameters: ultrasound output power, ultrasound frequency, pulse duration and pulse interval; and the modulation is performed on the basis of the rate of change of the system response parameter as evaluated by the feedback control module using the artificial intelligence module. [6] System according to claims 4 and 5, wherein the artificial intelligence module comprises a trained model configured to: receive historical data of system response parameters from previous anchoring operations; identify patterns that correlate the behavior of the system response parameters with the completion of the nanoparticle anchoring; and generate optimized ultrasonic parameter settings for the control unit based on a real-time comparison of the current system response parameter data with the identified patterns. [7] System according to claim 1, further comprising: a data storage module configured to store the system response parameter data measured during ultrasound irradiation, wherein an output port of the sensor is connected to the control unit and the data storage module. [8] System according to claim 1, further comprising a display module in conjunction with the data storage module and the control unit, wherein the display module is configured to provide a real-time visualization of the system response parameter and the stabilization status, and wherein the control unit is connected to the display module to display the status of the anchoring process and completion indicators.

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