Proper Topology Research Articles

Training Strategy of Fuzzy-Firefly Based ANN in Non-Linear Channel Equalization

Channel equalization is remaining a challenge for the researcher. Especially for the non-linear channel as well as the extremely dispersive channel, an effective channel equalizer is required. It is common knowledge that non-linear channel equalizers based on the neural networks (NN) outperform adaptive filter-based linear equalizers. To train NN equalizers, gradient-descent-based approaches like the back-propagation algorithm are often utilized, although they have drawbacks such as trapping of local minima, slower convergence, and compassion to log in. In this work, we presented a novel training strategy using a fuzzy firefly algorithm (FFA) for channel equalization. By using proper network topology and parameters, the suggested training system offers stronger exploitation and exploration skills, as well as the ability to solve the local minima issue. The performance of the equalizer can be analyzed by estimating two parameters i.e. MSE and BER. To exhibit the suggested technique’s resilience in performance, the burst error situation was used, and the outcomes showed that the strategy is more effective in managing such situations than previous methods. The outcomes of the proposed method are presented through simulation, Furthermore, it proved that the suggested method validates a wide range of SNR, and also it outperforms the existing NN-based equalizers.

Dynamic crushing behaviors and enhanced energy absorption of bio-inspired hierarchical honeycombs with different topologies

In order to pursue good crushing load uniformity and enchance energy absorption efficiency of conventional honeycombs, a kind of bio-inspired hierarchical honeycomb model is proposed by mimicking the arched crab shell structures. Three bio-inspired hierarchical honeycombs (BHHs) with different topologies are designed by replacing each vertex of square honeycombs with smaller arc-shaped structures. The effects of hierarchical topologies and multi-material layout on in-plane dynamic crushings and absorbed-energy capacities of the BHHs are explored based on the explicit finite element (FE) analysis. Different deformation modes can be observed from the BHHs, which mainly depend upon hierarchical topologies and impact velocities. According to energy efficiency method and one-dimensional (1D) shock theory, calculation formulas of densification strains and plateau stresses for the BHHs are derived to characterize the dynamic bearing capacity, which is consistent well with FE results. Compared with conventional honeycombs, the crushing load efficiency and energy absorption capacity of the BHHs can be improved by changing the proper hierarchical topology and multi-material layout. These researches will provide theoretical guidance for innovative design and dynamic response performance controllability of honeycombs.

Switching Ripple Harmonics Attenuation in DFIG and Matrix Converter-Based WECS

The analysis presented in this paper is focused on the harmonics distortion damping in the case of bidirectional power-flow of the electronics device—matrix converter as an interface between two power sources. Bidirectional energy flow takes place in the matrix converter that is used in renewables, hybrid transformers, microgrids, etc. It is observed that the matrix converter generates sinusoidal voltage with some amount of harmonic distortion and worsens in the quality of power in the utility grid. Taking into account the bi-directional energy flow and the matrix converter operation principle, four key requirements for the filters are formulated. Six theoretically possible filter topologies are investigated for compliance with these requirements. Two of the filter topologies are recognized as complying with these requirements and applicable for the switching ripple harmonics damping in the utility grid connected matrix converter in the case of bidirectional power flow. The suitability of these topologies was verified by MATLAB/Simulink simulation. Using the proper filter topology will significantly reduce the size, weight and cost of the components of the filter, as well as the utility grid’s pollution by switching ripple harmonics. It is appropriate to apply such filters to matrix converters that operate in wind turbines installed in doubly fed induction generators. These filters should also be used in hybrid transformers and other high-power devices with matrix converters.

HVDC Circuit Breakers: A Comprehensive Review

High voltage direct current (HVDC) systems are now well integrated into AC systems in many jurisdictions. The integration of renewable energy sources (RESs) is a major focus and the role of HVDC systems is expanding. However, the protection of HVDC systems against DC faults is a challenging issue that can have negative impacts on the reliable and safe operation of power systems. Practical solutions to protect HVDC grids against DC faults without a widespread power outage include: 1) using DC circuit breakers (CBs) to isolate the faulty DC-link, 2) using a proper converter topology to interrupt the DC fault current, and/or 3) using high-power DC transformers and DC hubs at strategic points within DC grids. The application of HVDC CBs is identified as the best approach that satisfies both DC grids and connected AC grids’ requirements. This article reports a comprehensive review of HVDC CBs technologies, including recent significant attempts in the development of modern HVDC CBs. The functional analysis of each technology is presented. Additionally, different technologies based on information obtained from literature are compared. Finally, recommendations for the improvement of CBs are presented.

Supercapacitors-based power supply for ASDEX upgrade toroidal field coils

ASDEX Upgrade (AUG) electrical power is provided with three Flywheel Generators (FGs) that are charged up before the start of each plasma pulse with 15 MW for 30 minutes. The stored energy is then used to satisfy the high power needs during the pulse of up to 400 MW. The biggest FG (‘EZ2’) in case of a major fault could not be replaced by any other FG of such size because no comparable devices are available on the free market. Therefore, the development of an alternative energy storage with high power and energy density and fully controllable output is planned. Supercapacitors (SCs) are well known for their high specific power. The combination of this technology and a proper power converter topology such as the Modular Multilevel Converter (MMC) represent a promising alternative to be explored to replace Tokamaks FGs. The MMC topology allows a discrete-leveled output voltage and, thanks to its high cells number, it can operate continuously even in case of fault of some cells, while a FG could not. In this paper the concept of a SCs-based power supply for AUG's Toroidal Field (TF) Coils is presented, highlighting the main advantages and challenges of this project.

Bidirectional DC–DC converter based multilevel battery storage systems for electric vehicle and large‐scale grid applications: A critical review considering different topologies, state‐of‐charge balancing and future trends

The expanding share of renewable energy sources (RESs) in power generation and rise of electric vehicles (EVs) in transportation industry have increased the significance of energy storage systems (ESSs). Battery is considered as the most suitable energy storage technology for such systems due to its reliability, compact size and fast response. Power converters are vital for the integration of batteries into power grid and EVs as they play an active role in both power conversion and battery management. Multilevel converters (MLCs) are types of power converters and attract widespread interest due to their improved power quality, reliability and modularity. There are two main challenges in MLC based battery storage systems (BSSs) which are selecting a proper MLC topology and balancing state-of-charges (SOCs) of batteries. Although some research has been carried out on either MLCs or SOC balancing, no single study exists which presents a comprehensive review on MLC based BSSs for large-scale grid and EV applications. This paper begins by reviewing several major battery storage technologies that are utilised in MLC based BSSs. Later on, a systematical review of commonly used and recently proposed MLC topologies for BSSs are provided along with different control schemes for MLCs by specifically focusing on SOC balancing techniques. Finally, potential challenges and suggestions for future improvement of MLC based BSSs are addressed.

Tubular parametric volume objects: Thickening a piecewise smooth 3D stick figure

In this paper, a volume parametric model is computed from a piecewise smooth skeleton. Generating a volume model from a stick figure S defined in 3D is an intuitive process: given S whose topology is a pseudo-graph and whose edges are embedded as Bézier curves in R3, we propose a method for creating a thick volume parametric model “around” S. The volume model we generate is based on semi-simploidal sets, which guarantees a proper topology and provides a 3D parametric domain for Bézier spaces. This volume is a continuous piecewise Bézier representation which boundary corresponds to a B-Rep made of tensor product Bézier patches.

Tetracycline removal from aqueous solution using zirconium-based metal-organic frameworks (Zr-MOFs) with different pore size and topology: Adsorption isotherm, kinetic and mechanism studies

The adsorptive removal of tetracycline (TC) was studied with three types of zirconium-based metal–organic frameworks (Zr-MOFs), UiO-66, NU-1000 and MOF-525. The adsorption kinetics best fitted with the pseudo-second-order kinetic model and the adsorption equilibrium was rapidly reached within 40 min on UiO-66 and NU-1000, and 120 min on MOF-525. The adsorption isotherms best fitted with Sips model, and the maximum Sips adsorption capacities of TC on UiO-66, NU-1000 and MOF-525 were 145 mg·g−1, 356 mg·g−1 and 807 mg·g−1 respectively, which were much higher than common adsorbents. The X-ray photoelectron spectra measurements and the influence of pH suggested that the π-π interaction played a crucial role during the adsorption. Pore characteristics and topology of MOFs showed great effect on adsorption performance. The cages whose size match well with TC helped MOF-525 to get highest adsorption amount per surface area among MOFs we studied. The proper topology of NU-1000 contributed to its high adsorption rate. River water was also used to confirm the excellent adsorptive performance of these three Zr-MOFs in practical application. These results might aid us to comprehend the adsorption of TC on Zr-MOFs and expand the application of Zr-MOFs in water treatment for removal of emerging contaminants.

Review of High-Frequency High-Voltage-Conversion-Ratio DC–DC Converters

The development of high-frequency power converters is continuously improving their power density, efficiency and fast dynamic response. Among them, high-voltage-conversion-ratio (HVCR) dc–dc converters are widely used in high gain, i.e., step-up/-down or bidirectional applications, such as power supply for data center, dc micro-grids, electrical vehicle charging systems, etc. In this article, the current main high-frequency HVCR dc–dc converters are classified into inductive-based and capacitive-based approaches, which can then be described further by four kinds in detail, namely transformer-based, coupled-inductor-based, and switched-capacitor-based, as well as combination of coupled inductor and switched capacitor. A comprehensive analysis and comparison is given, which can provide guidance for proper topology selection and further topology optimization.

Comparative Study of Switched Capacitor Converter Topologies for Wearable Devices

As wearable devices with low input voltages have drawn much attention from academic and industrial fields, the use of switched capacitor converters (SCC) also increases. This is because the wearable devices are required to utilize small size power converters and SCCs have no bulky circuit components such as magnetic components. Many kinds of SCCs have been suggested but they are based on three fundamental SCC topologies that are Dickson, series-parallel and Fibonacci topologies. In this study, three topologies are theoretically analyzed and simulated. With the results from them, a comparison is conducted to provide future circuit designers with a standard to choose a proper SCC topology for wearable devices.

Systematization of a Multilevel-Topology-Based Linear Amplifier Family for Noiseless DC–AC Power Conversion

Electrical power converters use semiconductor switching devices for larger loss reduction compared with non-switching power linear amplifier such as a class-B amplifier. However, it is well known that the switching operation produces harmonics and EMI noise, thus passive components are usually required for the suppression of these harmful sub-products. Use of recent fast power devices such as silicon carbide (SiC) and gallium nitride (GaN) devices produce larger dv/dt and di/dt than that of Si power devices and as a result above mentioned problem becomes more tangible. In this paper, the authors propose a concept of a family of multi-level linear amplifier (MLLA), which makes no switching power conversion possible. MLLA consist of series-connected switching devices and only one of them operates as a linear amplifier and the loss is much less than that of the class-B amplifier. The concept of the family is very useful when a proper MLLA topology might be selected for applications. In this paper, three kinds of MLLA—diode-clamped linear amplifier (DCLA), flying-capacitor linear amplifier (FCLA), and novel modular-cascaded linear amplifier (MCLA)—with four series connection of devices are investigated for the viewpoint of merits and demerits clarification and the efficiency over 82 % is demonstrated in the experiments.

Comparative Evaluation of Efficiency and Reliability of Single-Phase Five-Level NPC Inverters for Photovoltaic Systems

It is required to reduce the cost of PV energy to be competitive as an alternative energy source. The efficiency and reliability of PV inverters are important aspects to be enhanced to reduce the cost of PV energy since they contribute to the reduction of operational and maintenance costs and to the increase of annual energy production. Therefore, more comprehensive analysis on both efficiency and reliability together including the impacts of various factors is required. In this paper, single-phase five-level NPC inverter topologies for photovoltaic systems are comparatively evaluated in terms of efficiency and reliability by simulations and experiments, in which the impacts of pulse width modulation (PWM) methods and installation locations are considered. The results are expected to give an insight to determine the proper topology and PWM method depending on its installation location considering the reliability as well as the efficiency and total harmonic distortion (THD).

A novel approach for global solar irradiation forecasting on tilted plane using Hybrid Evolutionary Neural Networks

An efficient management of solar power systems requires direct and continuous predictions of global irradiation received on inclined planes. This paper proposes a new approach that simultaneously estimates and forecasts inclined solar irradiation. The method is based on a multi-task Hybrid Evolutionary Neural Network with two output neurons: one estimates the irradiation at the current instant and another predicts it for the next hour. An Evolutionary Algorithm is used to learn the most proper topology (number of neurons and connections). Two studies are carried out to evaluate the performance of the method, considering experimental ground data for the same inclination angle and satellite data with different tilt angles. The data only contain one measured variable, what improves its applicability to other sites. The potential of three different basis functions in the hidden layer is compared (Sigmoidal Units, Radial Basis Functions and Product Units), concluding that the results achieved by Sigmoidal Units are better. Single and multi-task models are also compared with a statistical analysis, which shows no significant differences. However, the proposed multi-task option is much simpler and computationally efficient than individual models. The problem tackled is more complex and challenging than previous works, due to inclined solar irradiation is predicted based on the horizontal irradiation and also because the model simultaneously estimates and predicts irradiation. However, the performance obtained is excellent compared to the literature.

Differential Power Processing Converter Enhancing Energy Yield of Curved Solar Roofs of Plug-In Hybrid Electric Vehicles

In photovoltaic (PV) panels consisting of multiple substrings connected in series, mismatch in substring characteristics due to partial shading causes the significant reduction in energy yield and the occurrence of multiple maximum power points. In solar roofs of plug-in hybrid electric vehicles (PHEVs), substring characteristics are always unavoidably mismatched due to the curvature of solar roofs, resulting in the mismatch issues similar to partial shading. Various kinds of differential power processing (DPP) converters have been proposed to preclude mismatch issues in traditional flat PV panels. The key contributions and novelties of this paper are summarized as follows. Firstly, uneven irradiance on the solar roof of Prius PHEVs is investigated. Secondly, existing DPP converter architectures are reviewed to select a proper DPP converter topology for PHEV applications. Thirdly, the selected topology is improved to be better suitable for PHEV applications, followed by the detailed operation analysis. Lastly, the experimental results of the laboratory and field testing using a prototype are presented. Field testing using an actual solar roof of Prius PHEV was performed, and the results demonstrated the daily energy yield enhancement of 4%–5% by the proposed DPP converter.

Energy conservation in query driven wireless sensor networks

Network topology used to connect sensor nodes is important factor in wireless sensor networks (WSNs) that affect the energy usage of any network. Proper topology connection thereby reduces energy usage of network by reducing number of packet transmissions. Therefore node connection must be optimized in wireless sensor networks. Hence we introduce a new multiple tree based architecture of sensor network, comprising of heterogeneous nodes, to develop an energy efficient query processing WSN application. This article proposes Multi-tree and Multiple-tree algorithms for improving network parameters in the usual data collection WSN application scenarios. A multi-tree simply suggests a strategy where similar parameter type sensors are arranged in a tree based topology so as to reduce the energy consumption as well as the end to end delay in data communication. The Multiple-tree exemplifies a more effective way of query result propagation in data centric applications where delay requirements are not very stringent.

A Practical Evaluation of ML Algorithms for a Tag-Based BLE Indoor Positioning System

In this paper, we evaluate the performance of machine learning (ML) algorithms employed in a commercial Bluetooth Low Energy (BLE) Indoor Positioning (IP) solution relying on practical measurements in a commercial office space setting. The BLE IP system utilizing tags presents an ideal economic approach for large facilities with a limited number of tracking elements (gateways). In this investigation, data collection campaigns were conducted in an indoor facility fitted with BLE gateways to aggregate Received Signal Strength Indicator (RSSI) <em>fingerprints</em>. Performance of a collection of well-known ML algorithms in terms of accuracy of positioning of the desired objects, in addition to training complexity and online tracking speed were evaluated. ML algorithms of increased accuracy and efficiency were identified and tabulated in both of the <em>offline</em> and <em>online</em> phases. It is also envisaged that as part of this practical study, the results will serve to identify proper economical topologies and configuration in real-life installations for tag-based BLE IP systems.

Quantum chemical topology from tight augmented core densities.

Based on parametrized tight Gaussian functions, an efficient and robust methodology designed to restore the effective core potentials electron densities and the inner shells of the electron localization function is introduced and tested. Attention is focused on the underlying effects of augmented coreless electron densities on selected quantum topological descriptors computed for a test set of species containing heavy elements such as the emblematic uranyl cation. Also, this article shows how a proper topology of the electron density can be recovered from semi-empirical Hückel calculations where core densities are missing.

Functional Assembly of the Mitochondrial Protein Transport Machinery

The vast majority of proteins that reside within mitochondria are encoded in nuclear DNA, synthesized on cytosolic ribosomes, and imported into the organelle. Within the mitochondrion reside several types of complex machineries that mediate the sorting, translocation and integration of incoming polypeptides based on their targeting information. Among these translocases, the TIM23 Complex mediates the import and biogenesis of most resident proteins, which are synthesized with cleavable amino‐terminal targeting sequences. The TIM23 Complex is a dynamic multi‐subunit assembly that serves versatile functions in mediating the transport of soluble proteins across the mitochondrial inner membrane as well as the lateral integration of membrane proteins. The multifunctional nature of this complex may arise from different modular states that it can assume based on its component subunits. Using a host of biophysical approaches, we have investigated the substrate‐ and energy‐dependent structural dynamics of the central subunit, the voltage‐gated channel Tim23. We have also analyzed the lipid interactions that mediate membrane associations with the receptor subunit, Tim50, as well as channel‐receptor interactions. To investigate the structure and function of the membrane‐sorting modular form of TIM23, we have utilized a reductionist approach in which five component subunits are purified from a heterologous expression system and reconstituted into a biomimetic model membrane. These subunits include the polytopic channel proteins Tim23 and Tim17, the Tim50 receptor, and additional membrane proteins Tim21 and Mgr2. The innovation of this system derives from the fact that multiple independently purified membrane proteins can form a functional complex spontaneously when reconstituted with the proper topology in a bilayer of synthetic lipids. This reconstituted complex provides a minimal system for the direct analysis of its channel features, its energetic requirements for mediating membrane protein integration, and the factors that mediate assembly, including lipid requirements. It also provides a highly purified system for structural analysis.Support or Funding InformationThis work was supported by NIH Grant 1R01GM113092 (to N.N.A.) and PSC‐CUNY Grant PSC‐CUNY 626860050 (to P.P.)

Regulated Alternative Translocation: A Mechanism Regulating Transmembrane Proteins Through Topological Inversion.

Transmembrane proteins must adopt a proper topology to execute their functions. In mammalian cells, a transmembrane protein is believed to adopt a fixed topology. This assumption has been challenged by recent reports that ceramide or related sphingolipids regulate some transmembrane proteins by inverting their topology. Ceramide inverts the topology of certain newly synthesized polytopic transmembrane proteins by altering the direction through which their first transmembrane helices are translocated across membranes. Thus, this regulatory mechanism has been designated as Regulated Alternative Translocation (RAT). The physiological importance of this topological regulation has been demonstrated by the finding that ceramide-induced RAT of TM4SF20 (Transmembrane 4 L6 family member 20) is crucial for the effectiveness of doxorubicin-based chemotherapy, and that dihydroceramide-induced RAT of CCR5 (C-C chemokine receptor type 5), a G protein-coupled receptor, is required for lipopolysaccharide (LPS) to inhibit chemotaxis of macrophages. These observations suggest that topological inversion through RAT could be an emerging mechanism to regulate transmembrane proteins.

Interdigital Hyperplasia in Holstein Cattle Is Associated With a Missense Mutation in the Signal Peptide Region of the Tyrosine-Protein Kinase Transmembrane Receptor Gene.

Bovine interdigital hyperplasia (IH) is a typical disease of the foot with varying prevalence depending on age, breed, and environmental factors resulting in different degrees of lameness. In studies based on assessments of claw health status at time of hoof trimming and applying genetic-statistical models to analyze this data, IH consistently exhibits high estimates of heritability in the range of 0.30–0.40. Although some studies have identified chromosomal regions that could possibly harbor causative genes, a clear identification of molecular causes for IH is lacking. While analyzing the large database of claw health status as documented at time of hoof trimming, we identified one herd with extreme prevalence of IH of > 50% of affected Holstein dairy cows. This herd subsequently was chosen as the object of a detailed study. A total of n = 91 cows was assessed and revealed a prevalence of 59.3% and 38.5% for IH cases, documented as “one-sided” or “two-sided”, respectively. Cows were genotyped using the BovineSNP50 BeadChip. A genome wide association study revealed two significantly associated chromosomal positions (-log10P = 5.57) on bovine chromosome 8 (BTA8) located in intron 5 and downstream of the receptor tyrosine kinase-like orphan receptor 2 (ROR2) gene. As ROR2 plays a key role in ossification of the distal limbs and is associated with brachydactylies in humans, it was a reasonable candidate for IH. A comparative sequencing of the ROR2 gene between cases and controls revealed two missense variants in exon 1 (NC_037335.1:g.85,905,534T > A, ARS-UCD1.2) and exon 9 (NC_037335.1:g.86,140,379A > G, ARS-UCD1.2), respectively. Genotyping of both variants in the cohort of 91 cattle showed that the exon 1 variant (rs377953295) remained significantly associated with IH (p < 0.0001) as a risk factor of the disease. This variant resulted in an amino acid exchange (ENSBTAP00000053765.2:p.Trp9Arg) in the N-terminal region of the ROR2 signal peptide which is necessary for proper topology of the polypeptide during translocation. Quantification of ROR2 mRNA and ROR2 protein showed that the variant resulted in a significant suppression of ROR2 expression in homozygous affected compared to wild type and carrier cows.