Topology Control Research Articles

Patching Non-Uniform Extraordinary Points.

Smooth surfaces from an arbitrary topological control grid have been widely studied, which are mostly generalized from splines with uniform knot intervals. These methods fail to work well on extraordinary points (EPs) whose edges have varying knot intervals. This article presents a patching solution for arbitrary topological 2-manifold control grid with non-uniform knots that defines one bi-cubic Bézier patch per control grid face except those faces with EPs. Experimental results demonstrate that the new solution can improve the surface quality for non-uniform parameterization. Applications in surface reconstruction, arbitrary sharp features on the complex surface and tool path planning for the new surface representation are also provided in the paper.

Artificial Channels Based on Bottlebrush Polymers: Enhanced Ion Transport Through Polymer Topology Control.

Synthetic structures mimicking the transport function of natural ion channel proteins have a wide range of applications, including therapeutic treatments, separation membranes, sensing, and biotechnologies. However, the development of polymer-based artificial channels has been hampered due to the limitation on available models. In this study, we demonstrate the great potential of bottlebrush polymers as accessible and versatile molecular scaffolds for developing efficient artificial ion channels. Adopting the bottlebrush configuration enhanced ion transport activity of the channels compared to their linear analogs. Matching the structure of lipid bilayers, the bottlebrush channel with a hydrophilic-hydrophobic-hydrophilic triblock architecture exhibited the highest activity among the series. Functionalized with urea groups, these channels displayed high anion selectivity. Additionally, we illustrated that the transport properties could be fine-tuned by modifying the chemistry of ion binding sites. This work not only highlights the importance of polymer topology control in channel design, but also reveals the great potential for further developing bottlebrush channels with customized features and diverse functionalities.

Artificial Channels Based on Bottlebrush Polymers: Enhanced Ion Transport Through Polymer Topology Control

AbstractSynthetic structures mimicking the transport function of natural ion channel proteins have a wide range of applications, including therapeutic treatments, separation membranes, sensing, and biotechnologies. However, the development of polymer‐based artificial channels has been hampered due to the limitation on available models. In this study, we demonstrate the great potential of bottlebrush polymers as accessible and versatile molecular scaffolds for developing efficient artificial ion channels. Adopting the bottlebrush configuration enhanced ion transport activity of the channels compared to their linear analogs. Matching the structure of lipid bilayers, the bottlebrush channel with a hydrophilic‐hydrophobic‐hydrophilic triblock architecture exhibited the highest activity among the series. Functionalized with urea groups, these channels displayed high anion selectivity. Additionally, we illustrated that the transport properties could be fine‐tuned by modifying the chemistry of ion binding sites. This work not only highlights the importance of polymer topology control in channel design, but also reveals the great potential for further developing bottlebrush channels with customized features and diverse functionalities.

Machine-learning based control of bi-modular multilevel PWM inverter for high power applications.

This paper presents the topology and machine learning-based intelligent control of high-power PV inverter for maximum power extraction and optimal energy utilization. Modular converters with reduced components economic and reliable for high power applications. The proposed integrated intelligent machine learning based control delivers power conversion control with maximum power extraction and supervisory control for optimal load demand control. The topology of the inverter, operating modes, power control and supervisory control aspects are presented. Simulation is carried out in MATLAB/SIMULINK to verify the feasibility of the proposed inverter and control algorithm. The experimental study is presented to validate the simulation results. The operational performance of the proposed topology is evaluated in terms of operational parameters such as regulation of output power, and load relay control and is compared to existing topologies. The economic performance is also evaluated in terms of power switch sizing and reliability in power delivery concerning switch or power sources failure.

Distributed clustering model for energy efficiency based topology control using game theory in wireless sensor networks

In this study, we use a topology control technique to tackle the issue of energy balance and consumption minimization in wireless sensor networks. By maintaining network connection while sensibly adjusting the transmission power level, such an algorithm may reduce and balance energy usage. This study provides an energy welfare topological control using a game-theoretic approach by calculating energy welfare as usefulness metric for energy populations using the welfare function from the social sciences. Energy balance occurs when every node works to improve its local society's energy situation to the best of its ability. We demonstrate that the consequence ant game is an intriguing game with a single Nash equilibrium that is Pareto optimum. According to economic theory, Pareto optimality is a situation in which improving one person's circumstances would always make another person's worse off. We demonstrate our suggested methodology's superiority in establishing energy balance and efficiency in wireless sensor networks by contrasting the simulation results of our algorithm with those of other approaches. Our approach surpasses existing methods by a wide margin. For reliable and long-lasting wireless sensor applications, this study offers insightful information about how to maximize network performance while preserving energy resources.

Design and implementation of an innovative single-phase direct AC-AC bipolar voltage buck converter with enhanced control topology

Direct AC–AC converters are strong candidates in the power converting system to regulate grid voltage against the perturbation in the line voltage and to acquire frequency regulation at discrete step levels in variable speed drivers for industrial systems. All such applications require the inverted and non-inverted form of the input voltage across the output with voltage-regulating capabilities. The required value of the output frequency is gained with the proper arrangement of the number of positive and negative pulses of the input voltage across the output terminals. The period of each such pulse for low-frequency operation is almost the same as the half period of the input grid or utility voltage. These output pulses are generated by converting the positive and negative input half cycles in noninverting and inverting forms as per requirement. There is no control complication to generate control signals used to adjust the load frequency as the operating period of the switching devices is normally greater than the period of the source voltage. However, high-frequency pulse width modulated (PWM) control signals are used to regulate the output voltage. The size of the inductor and capacitor is inversely related to the value of the switching frequency. Similarly, the ripple contents of voltage and currents in these filtering components are also inversely linked with PWM frequency. These constraints motivate the circuit designer to select high PWM frequency. However, the alignment of the high-frequency control input with the variation in the input source voltage is a big challenge for a design engineer as the switching period of a high-frequency signal normally lies in the microsecond. It is also required to operate some high-frequency devices for various half cycles of the source voltage, creating control complications as the polarities of the half cycles are continuously changing. This requires at least the generation of two high-frequency signals for different intervals. The interruption of the filtering inductor current is a big source of high voltage surges in circuits where the high-frequency transistors operate in a complementary way. This may be due to internal defects in the switching transistors or some unnecessary inherent delay in their control signals. In this research work, a simplified AC–AC converter is developed that does not need alignment of high-frequency control with the polarity of the source voltage. With this approach, high-frequency signals can be generated with the help of any analog or digital control system. By applying this technique, only one high-frequency control signal is generated and applied in AC circuits, as in a DC converter, without applying a highly sensitive polarity sensing circuit. So, controlling complications is drastically simplified. The circuit and configuration always avoid the current interruption problem of filtering the inductor. The proposed control and circuit topology are tested both in computer-based simulation and practically developed circuits. The results obtained from these platforms endorse the effectiveness and validation of the proposed work.

Topologically controlled synthesis of active colloidal bipeds

Topological growth control allows to produce a narrow distribution of outgrown colloidal rods with defined and adjustable length. We use an external magnetic field to assemble paramagnetic colloidal spheres into colloidal rods of a chosen length. The rods reside above a metamorphic hexagonal magnetic pattern. The periodic repetition of specific loops of the orientation of an applied external field renders paramagnetic colloidal particles and their assemblies into active bipeds that walk on the pattern. The metamorphic patterns allow the robust and controlled polymerization of single colloids to bipeds of a desired length. The colloids are exposed to this fixed external control loop that causes multiple simultaneous responses: Small bipeds and single colloidal particles interpret the external magnetic loop as an order to walk toward the active zone, where they assemble and polymerize. Outgrown bipeds interpret the same loop as an order to walk away from the active zone. The topological transition occurs solely for the growing biped and nothing is changed in the environment nor in the magnetic control loop. As in many biological systems the decision of a biped that reached its outgrown length to walk away from the reaction site is made internally, not externally.

UPQC-Based Hybrid Technique to Reduce Power Quality Problems in the Photovoltaic Grid System

In addition to Power Quality (PQ) problems caused by solid state devices in the distribution side of grid connected Photo Voltaic (PV) system, quality of power also suffers in the source side by the usage of converters. Generally, PQ problems mitigation strategy has turned into a critical issue in grid-connected PV systems. This paper proposes a control topology for PQ issues mitigation scheme in grid connected PV systems. The primary goal of this study is to enhance the PQ in power distribution system through eradicating the voltage interruption, voltage swell and sag as well as voltage fluctuation. To accomplish these changes, Unified Power Quality Conditioners (UPQCs) with controllers were utilized. Then the faults are mitigated by the utilization of UPQC with Tree Seeds Algorithm (TSA) — Adaptive Neuro-Fuzzy Interference System (ANFIS). At first, the normal properties of the grid-connected PV systems are dissected. From that point forward, a few interruptions are made in the system and the abnormal characteristics are analyzed. Then the abnormal characteristics of PQ problems are diminished in the utilization of UPQC and TSA–ANFIS controllers. UPQC is one of the best filters topologies which can mitigate and control all PQ problems. The combined algorithms of TSA-ANFIS are used to keep the dc-link voltage in UPQC at consistent level. The proposed hybrid approach is executed in MATLAB/Simulink platform and the performance is studied. Further, the proposed method is compared with existing Elephant Herding Optimization (EHO) technique and also with hybrid EHO-ANFIS techniques. The comparison results showed that the proposed technique is superior to the EHO and EHO-ANFIS techniques.

From Bioreactor to Bulk Rheology: Achieving Scalable Production of Highly Concentrated Circular DNA.

DNA serves as a model system in polymer physics due to its ability to be obtained as a uniform polymer with controllable topology and nonequilibrium behavior. Currently, a major obstacle in the widespread adoption of DNA is obtaining it on a scale and cost basis that accommodates bulk rheology and high-throughput screening. To address this, recent advancements in bioreactor-based plasmid DNA production is coupled with anion exchange chromatography producing a unified approach to generating gram-scale quantities of monodisperse DNA. With this method, 1.1 grams of DNA is obtained per batch to generate solutions with concentrations up to 116mg mL-1. This solution of uniform supercoiled and relaxed circular plasmid DNA, is roughly 69 times greater than the overlap concentration. The utility of this method is demonstrated by performing bulk rheology measurements at sample volumes up to 1 mL on DNA of different lengths, topologies, and concentrations. The measured elastic moduli are orders of magnitude larger than those previously reported for DNA and allowed for the construction of a time-concentration superposition curve that spans 12 decades of frequency. Ultimately, these results can provide important insights into the dynamics of ring polymers and the nature of highly condensed DNA dynamics.

A Flexible Topology Control Strategy for Mega-Constellations via Inter-Satellite Links Based on Dynamic Link Optimization

In large-scale satellite constellations, the efficiency of inter-satellite communication is paramount. Traditional topology control strategies, such as the Manhattan configuration, provide stable links but can result in indirect communication paths, affecting the efficiency of information transfer. This paper addresses this issue by proposing an innovative “3 + 1” dynamic topology control scheme. The scheme retains three static links determined by the relative angular velocity and acceleration while introducing a dynamic link based on distance and angular velocity constraints to optimize the link duration and overall network communication efficiency. To address the complexity of matching dynamic links, this paper introduces an elite strategy-based maximum weighted matching algorithm for general graphs. Compared to traditional greedy algorithms, our proposed algorithm significantly improves the link duration and topological stability. Through simulation experiments comparing communication delays between Xiamen and Los Angeles, our results show that the proposed dynamic link scheme substantially reduces the average delay, enhancing the efficiency and flexibility of inter-satellite communication. This research not only extends the duration of inter-satellite links but also provides new perspectives and methodologies for further studies on inter-satellite topology control strategies.

Poincaré Inequality and Topological Rigidity of Translators and Self-Expanders for the Mean Curvature Flow

We prove an abstract structure theorem for weighted manifolds supporting a weighted f-Poincaré inequality and whose ends satisfy a suitable non-integrability condition. We then study how our arguments can be used to obtain full topological control on two important classes of hypersurfaces of the Euclidean space, namely translators and self-expanders for the mean curvature flow, under either stability or curvature asumptions. As an important intermediate step in order to get our results we get the validity of a Poincaré inequality with respect to the natural weighted measure on any translator and we prove that any end of a translator must have infinite weighted volume. Similar tools can be obtained for properly immersed self-expanders permitting to get topological rigidity under curvature assumptions.

Centroid-Guided Target-Driven Topology Control Method for UAV Ad-Hoc Networks Based on Tiny Deep Reinforcement Learning Algorithm

Centroid-Guided Target-Driven Topology Control Method for UAV Ad-Hoc Networks Based on Tiny Deep Reinforcement Learning Algorithm

Topology derivation and control method of high‐reliability buck‐boost double‐grounded transformerless three‐phase inverters

SummaryAs the traditional transformerless three‐phase (TTP) inverters have the shoot‐through and common mode leakage current (CMLC) problems, as well as not being able to realize the buck‐boost conversion, topology derivation and control method of high‐reliability buck‐boost double‐grounded TTP inverters are proposed. These topologies consist of two‐port or three‐port converters with boost capability and three dual‐buck inverters. The two‐port or three‐port converters with boost capability provide the positive and negative bus voltages for the three dual‐buck inverters, realizing the boost conversion. The dual‐buck inverters address the shoot‐through problem. The double‐grounded structure is used to solve the CMLC problem. Dead time between switches is not needed, which reduces the complexity of the control system. Detailed topology derivation of the dual‐buck double grounded TTP inverters with boost capability is given. The operating principle, parameters design of the filters, and stability analysis of this inverter are analyzed in detail. Loss analysis of the inverter is given. The simulation and experimental results of a 750‐W TTP inverter are used to verify the theoretical analysis.

Incremental swarm coordination control with self-triggered-organized topology and predictive-based control method

This work focuses on coordinating a swarm of multiple mobile robots with incremental joining units using an incremental-self-organized formation (ISOF) scheme. The ISOF scheme enables the assimilation of newly joined robots and autonomously establishes a feasible communication topology between the incremental and existing robots. To avoid redundant generation, the new communication topology is expanded and updated based on the existing topology while preserving the original structure. To realize the real-time update of control model and topology for generalized swarm system using the ISOF scheme, an incremental-self-triggered updating mechanism (ISTUM) is designed, and specific triggering conditions are defined. With the updated communication topology and control model, the incremental swarm system, subject to predefined constraints, can be controlled to achieve the desired formation objective using a model-predictive-control-based (MPC-based) protocol. The proposed control scheme aims to minimize the need for manual intervention in swarm reconstruction when incremental behaviour occurs, thereby enhancing the flexibility of swarm coordination. Simulation results demonstrate the effectiveness of the developed control scheme.

The Quasi-Resonant Structure and Control Strategy of a Photovoltaic Flyback Grid-Connected Microinverter

This study proposes a topology structure for a flyback grid-connected inverter with a compensation capacitor. The addition of the compensation capacitor structure increases the harmonic oscillation period and reduces the switching frequency. Additionally, a control strategy for the microinverter is proposed. By using an accurate peak current reference curve, the system ensures precise turn-off signals, thus reducing the harmonic content of the grid-connected current. Simultaneously, the multi-valley turn-on strategy is employed to address the issue of high switching frequency, minimising the impact of energy. The proposed topology structure and control methods are modelled, simulated, and tested to validate the feasibility of the microinverter topology structure and the effectiveness of the control strategy, achieving a maximum efficiency of 95.2% and controlling the total harmonic distortion (THD) below 2.39%. Compared to other microinverter products, it is more efficient and stable.

Size- and Shape-controlled Biodegradable Polymer Brushes Based on l-Amino Acid for Intracellular Drug Delivery and Deep-Tissue Penetration.

We report size- and shape-controlled polymer brushes based on l-amino acid bioresource and study the role of polymer topology on the enzymatic biodegradation and deep-tissue penetration under in vitro and in vivo. For this purpose, l-tyrosine-based propargyl-functionalized monomer is tailor-made and polymerized via solvent-free melt polycondensation strategy to yield hydrophobic and clickable biodegradable poly(ester-urethane)s. Postpolymerization click chemistry strategy is applied to make well-defined amphiphilic one-dimensional rodlike and three-dimensional spherical polymer brushes by merely varying the lengths of PEG-azides in the reaction. These core-shell polymer brushes are found to be nontoxic and nonhemolytic and capable of loading clinical anticancer drug doxorubicin and deep-tissue penetrable near-infrared biomarker IR-780. In vitro enzymatic drug-release kinetics and lysotracker-assisted real-time live-cell confocal bioimaging revealed that the rodlike polymer brush is superior than its spherical counterparts for faster cellular uptake and enzymatic biodegradation at the endolysosomal compartments to release DOX at the nucleus. Further, in vivo live-animal bioimaging by IVIS technique established that the IR-780-loaded rodlike polymer brush exhibited efficient deep-tissue penetration ability and emphasized the importance of polymer brush topology control for biological activity. Polymer brushes exhibit good stability in the blood plasma for more than 72 h, they predominately accumulate in the digestive organs like liver and kidney, and they are less toxic to heart and brain tissues. IVIS imaging of cryotome tissue slices of organs confirmed the deep-penetrating ability of the polymer brushes. The present investigation opens opportunity for bioderived and biodegradable polymer brushes as next-generation smart drug-delivery scaffolds.

Research on dynamic stability of rolling missiles employing direct/aerodynamic force compound control

The direct/aerodynamic force compound control can enhance the maneuverability and response characteristics of missiles, and the dynamic stabilization is the precondition of normal operation for rolling missiles. Aiming at the stability problem caused by the cross-coupling effect of rolling missiles employing direct/aerodynamic force compound control, proposing a typical topological control system structure described by the complex coefficient theory, and deducing the dynamic stability conditions. Firstly, the mathematic model is established based on the kinematics and dynamics theories of rotating airframes and the direct/aerodynamic force compound control mechanism. Then, a three-loop autopilot and the direct/aerodynamic force ratio distribution method are designed to establish the complex summation model of the compound control system by selecting suitable complex variables. Furthermore, deducing the dynamic stability conditions and verifying them by numerical simulations. Finally, the stable regions of the rolling missile in different cases are obtained and found to be influenced by many factors, such as parameters of the autopilot, hybrid force distribution proportion and rolling rate. The derived dynamic stability criterion is effective for evaluating the stability of rolling missiles employing direct/aerodynamic force compound control and the research method used in this paper can provide reference for the stability study of strongly coupled nonlinear systems.

CHEABC-QCRP: A novel QoS-aware cluster routing protocol for industrial IoT

Clustering routing protocols currently have problems such as Single point of failure of cluster head nodes, poor network dynamics, uneven data transmission, etc., which are critical to the optimization of energy efficiency, network lifespan and network topology control. However, this optimization problem is an NP hard problem that conventional algorithms are difficult to solve. This paper proposes a new multi-objective cluster routing protocol (CHEABC-QCRP) aimed at optimizing network energy consumption, system lifespan, and quality of services (QoS). The protocol is based on a new chaotic hybrid elite artificial bee colony algorithm (CHEABC) proposed in this paper, which has strong search ability and greatly reduces convergence time. At the same time, a new chaotic strategy was designed to effectively prevent falling into local optima and premature convergence. In simulation experiments, compared with multiple routing protocols, a large number of test results show that this protocol significantly reduces network energy consumption, greatly improves system lifespan, and effectively improves QoS in IWSN.

Dual-Coupled-Inductor-Based High-Step-Up Boost Converter with Active-Clamping and Zero-Voltage Switching

Many applications, such as photovoltaic systems, uninterruptible power supplies, and automobile headlamps, need a high step-up DC–DC converter without isolation. The conventional boost converter has the advantages of simple topology and easy control. However, it has some shortcomings, such as insufficient step-up voltage ratio and poor efficiency when operating at large duty-cycle conditions. One of the popular topologies used to overcome these problems is the coupled-inductor boost converter. It utilizes the turn ratio of the coupled inductor to realize a higher step-up voltage ratio. The drawback is that the leakage inductance of the coupled inductor causes a huge voltage spike when the power switches are turned off. Moreover, because coupled inductors are characterized by their large volume and high profile, a conventional coupled-inductor boost converter is unsuited for photovoltaic systems, such as the solar microinverter. This study proposes a novel high-step-up boost converter to solve these problems. This proposed converter uses dual coupled inductors instead of the conventional coupled-inductor boost converter. The secondary side of the coupled inductor is connected in series to increase the step-up voltage ratio. The proposed converter utilizes active clamping to achieve zero-voltage switching (ZVS) for suppressing voltage spike and improving conversion efficiency. In addition, low-profile designs can be fulfilled easily for solar microinverters. The proposed converter and its control method are introduced. The operation principle, circuit characteristics, and circuit analysis are presented. A prototype converter with 300 W output power 25–40 VDC input voltage and 200 VDC output voltage was tested. All functions, including high step-up voltage ratio, ZVS, and active clamping, were achieved, and the highest efficiency was around at 94.7%.

Stability Analysis in Multi-VSC (Voltage Source Converter) Systems of Wind Turbines

In this paper, a holistic nonlinear state-space model of a system with multiple converters is developed, where the converters correspond to the wind turbines in a wind farm and are equipped with grid-following control. A novel generalized methodology is developed, based on the number of the system’s converters, to compute the equilibrium points around which the model is linearized. This is a more solid approach compared with selecting operating points for linearizing the model or utilizing EMT simulation tools to estimate the system’s steady state. The dynamics of both the inner and outer control loops of the power converters are included, as well as the dynamics of the electrical elements of the system and the digital time delay, in order to study the dynamic issues in both high- and low-frequency ranges. The system’s stability is assessed through an eigenvalue-based stability analysis. A participation factor analysis is also used to give an insight into the interactions caused by the control topology of the converters. Time domain simulations and the corresponding frequency analysis are performed in order to validate the model for all the control interactions under study.