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Due to the low voltage and high randomness of renewable energy, high-performance grid-connected converters are needed. With the advantages of a high boost ratio, flexible design, and simple control, the Y-Source Converter (YSC) is widely concerned. However, there are a few drawbacks to the traditional Y-source converter, including significant switching stress, voltage voltage overshoot, and discontinuous current. To solve the problems above, a series of improved topologies are proposed. Moreover, the voltage gain, current ripple, and soft switching characteristics have also been optimized. So far, the existing literature lacks the collation and comparison of different topologies of Y-source, as well as the analysis of its evolution process. Therefore, this paper provides a comprehensive overview of Y-source converters' topologies. According to their features and applications, different topologies are classified and described, leading to guidance for the selection of YSCs under different scenarios. Meanwhile, the working principle, evolution process, and vital issues are analyzed. By revealing their deductive rules, valuable suggestions are provided for the future development of YSCs. [ABSTRACT FROM AUTHOR]

This article presents the proposition, application, and results of a graduate course focused on practical aspects of developing converters and applications in Power Electronics. The initial motivation behind the initiative was to mitigate the loss of laboratory experience resulting from the closure of laboratories or restrictions on shared access imposed by the COVID-19 pandemic, resulting in the breakdown of the synergistic experience that characterizes practical activities in the research environment. Over time, it was realized that the lack of practical experience in power electronics activities was related to structural issues in the training of engineers, and the pandemic worsened the situation. This signaled that the course could and should be offered regularly. Five themes were focused on topologies, power devices, passive devices, electromagnetic compatibility, thermal design, and electronic and control circuits. The activities included theoretical classes, laboratory classes, technical visits, and simulation exercises, ending with a final project. At the end of the course, an evaluation process with the students made it possible to verify a significant gain in knowledge in the different topics covered, especially in topics less emphasized in traditional courses, such as magnetics components design, printed circuit board development, thermal analysis, and EMC aspects.

The smart street-lighting system (SSLS) is a leading candidate in the smart city. By the time of the last 15 cycles, many meaningful improvements have been executed in the SSLS with the impact of the internet of things technologies and universal networking devices. Conventional smart street lighting systems are restricted to wireless sensor networks, mobile devices, and old lighting control systems. This article presents a comprehensive treatment of network designs, namely communication, control, and wireless sensor-based smart street lighting system by deploying based on their existing system architecture, and network topologies including leading with it a host of privileges. In addition, choosing the right lighting class, high-intensity discharge (HID) lights, and retrofitting lighting technologies have all been covered in detail. This paper's objective is to evaluate various control technologies that may support the many applications deployed on networked streetlights. Moreover, issues and recommendations, distinguished in this paper, will pave the route for future smart street lighting systems that promote a reliable and seamless driving experience and are energy-efficient for environmental sustainability. It is far anticipated that LoRa and Sigfox with additional gateways could be the best possible smart street lighting system options as these technologies are facilitated for long distances but with a limited data rate. It is way more suitable for lighting control compared to other protocols to control thousands of streetlights.

Due to the low voltage and high randomness of renewable energy, high-performance grid-connected converters are needed. With the advantages of a high boost ratio, flexible design, and simple control, the Y-Source Converter (YSC) is widely concerned. However, there are a few drawbacks to the traditional Y-source converter, including significant switching stress, voltage voltage overshoot, and discontinuous current. To solve the problems above, a series of improved topologies are proposed. Moreover, the voltage gain, current ripple, and soft switching characteristics have also been optimized. So far, the existing literature lacks the collation and comparison of different topologies of Y-source, as well as the analysis of its evolution process. Therefore, this paper provides a comprehensive overview of Y-source converters’ topologies. According to their features and applications, different topologies are classified and described, leading to guidance for the selection of YSCs under different scenarios. Meanwhile, the working principle, evolution process, and vital issues are analyzed. By revealing their deductive rules, valuable suggestions are provided for the future development of YSCs.

Smart concrete is capable of self-assessing its state of stress and strain. It is produced by tailoring the electrical conductivity of concrete with the addition of conductive materials such as carbon fiber. This paper aims at determining the electrical conductivity of smart concrete materials with randomly dispersed carbon fibers. It unravels the conduction mechanism and establishes a theoretical basis of the percolation threshold for conduction. A numerical model for concrete with carbon fiber is developed. The electrical conduction through the concrete is calculated by solving the governing equations based on Kirchhoff's reformulation of Ohm's Law. More than ten thousand cases with varying fiber topologies, fiber fraction ratios and aspect ratios have been generated to account for the randomness of distribution and their electrical properties are evaluated. By analyzing those results, the mechanism behind the percolation threshold is explained. Finally, an algebraic relationship is posited to determine the percolation threshold has been evaluated. The relationship has been validated with experimental results. The results are extremely valuable for the design of self-sensing smart concrete. [ABSTRACT FROM AUTHOR]

The positions of sensor nodes in wireless sensor networks (WSNs) plays important role in order to achieve optimum values of various parameters, such as coverage, localization, etc. WSNs are used in every field such as in agriculture, military etc. and to achieve optimum performance of WSNs in these fields the sensor nodes are required to deploy at optimized positions. In this paper the jaya-sine cosine optimization algorithm (Jaya-SCOA) is proposed to deploy the sensor nodes at optimum positions and to increase the coverage of sensor nodes. Further the sensor nodes are deployed in three different topologies such as C shape, outer boundary and random topology and coverage rate is computed for all topologies. The major goal of the paper is to find the best topology for deploying the sensor nodes in WSNs and to enhance the coverage of nodes. The simulation results of proposed Jaya-SCOA is compared with fruit fly optimization algorithm (FFOA) and bat optimization algorithm (BOA) for all topologies in terms of maximum and minimum coverage, standard deviation and mean coverage rate. The simulation results demonstrate that for all topologies the coverage rate of Jaya-SCOA is higher than that of FFOA and BOA and average coverage rate of Jaya-SCOA for random topology is increased by 14.55% and 27.04% as compared to outer boundary and C shape topology, respectively. Therefore, the random topology is the best topology as compared to other topologies and Jaya-SCOA is effective than BOA and FFOA for all topologies in terms of coverage and stability. [ABSTRACT FROM AUTHOR]

Early Modern choir stalls are spaces within spaces, they separate spheres such as public and restricted, profane and holy, as well as open and closed. Members of the convents perform their daily devotions here and are assigned to respective seats. They are installed, according to the name of the place “stalla”. The inlaid decoration on each seat reiterates the specific spatial and religious formation. This article wants to explore how choir stalls immerse their users and viewers in pictorial and religious environments.

Grid-connected converters (GCCs) are used extensively for the integration of DC power sources with AC power sources. However, since it is a complex topic, there are many possibilities for regulating grid-injected currents, as well as different modulation techniques for generating full-bridge PWM voltages. The control techniques are directly related to the type of output filter, as well as to the topology of the converter, since a complex plant can require more sophisticated controllers to keep the system stable, and with good regulation performance. Furthermore, a discussion of the applicability of these converters in weak and very weak grids with high inductance content has recently been growing, which adds a greater degree of complexity to the control structure of the converter. In this brief overview are outlined some topics about topologies, output filters, and control, focusing on the current regulation of grid-connected converters. In addition, a discussion of the main challenges and critical areas in operating on weak and very weak grids is also presented. [ABSTRACT FROM AUTHOR]

The wide-scale adoption and accelerated growth of electric vehicle (EV) use and increasing demand for faster charging necessitate the research and development of power electronic converters to achieve high-power, compact, and reliable EV charging solutions. Although the fast charging concept is often associated with off-board DC chargers, the importance of on-board AC fast charging is undeniable with the increasing battery capacities. This article comprehensively reviews gallium nitride (GaN) semiconductor-based bidirectional on-board charger (OBC) topologies used in both 400 V and 800 V EV applications. Moreover, comparative evaluations of GaN-based bi-directional OBC topologies regarding power conversion losses (conduction loss and soft switching capabilities), power density, implementation considerations, power quality, electromagnetic interference, and reliability aspects have been presented. The status of commercially available GaN power modules, advancements in GaN technology, applicable industry standards, and application requirements for OBCs have been also included in this study. Finally, in light of forthcoming advancements in GaN power transistor technology, this study highlights potential areas of research related to the reviewed topologies. Such research can aid researchers and designers in improving the performance and user experience of electric vehicles, ultimately supporting the widespread adoption of EVs. [ABSTRACT FROM AUTHOR]

Abstract Covid-19 is a disease that can lead to pneumonia, respiratory syndrome, septic shock, multiple organ failure, and death. This pandemic is viewed as a critical component of the fight against an enormous threat to the human population. Deep convolutional neural networks have recently proved their ability to perform well in classification and dimension reduction tasks. Selecting hyper-parameters is critical for these networks. This is because the search space expands exponentially in size as the number of layers increases. All existing approaches utilize a pre-trained or designed architecture as an input. None of them takes design and pruning into account throughout the process. In fact, there exists a convolutional topology for any architecture, and each block of a CNN corresponds to an optimization problem with a large search space. However, there are no guidelines for designing a specific architecture for a specific purpose; thus, such design is highly subjective and heavily reliant on data scientists’ knowledge and expertise. Motivated by this observation, we propose a topology optimization method for designing a convolutional neural network capable of classifying radiography images and detecting probable chest anomalies and infections, including COVID-19. Our method has been validated in a number of comparative studies against relevant state-of-the-art architectures.

PV systems are penetrating the energy generation market rapidly and their output strongly depends on environmental conditions. To maximize the energy yield, the utilization of power electronic converters with maximum power tracking function is mandatory. Typically, the dc voltage generated by PV is fed into the ac grid using an dc-ac inverter. On the other hand, most modern loads, from small to large ones, are based on dc. Hence, wide adoption of residential dc microgrids (RDC $\mu $ Gs) based on PV energy generation becomes a trend that is following the developments in modern energy-efficient buildings. This paper targets power converters for the integration of PV systems into RDC $\mu $ Gs. It considers two main classes: high step-up converters for PV module-level (parallel optimizer) applications and non-isolated buck-boost converters for the PV string (series optimizer) applications. Due to the importance of the PV topic, a significant number of topologies have been introduced in the literature. However, only selected solutions attracted the interest of the industry. This review paper considers PV converters used in the industry or demonstrated in academic publications at a high technology readiness level with comprehensive experimental justification. This allows us to focus this review on the most valuable solutions and to provide a guide for both industry and academic readers. In the end, future trends in industrial PV systems and associated power converters are discussed.

In the coming years, major transportation sectors will be electrified, in which more accessible and easy solutions for charging Electric Vehicles (EVs) become vital. Wireless charging is considered one of the best and easiest methods to charge EVs anywhere, even during the driving of cars. To get accurate charging power rates while charging wirelessly, advanced mathematical models are needed to accurately present the charging power. Such models must take into consideration all the coils parameters, shapes, the used compensation topology, and if the system is static or dynamic. This paper presents a comprehensive analysis of the wireless charging systems adapted for EVs by stating the most common charging topologies, and architectures, and by concentrating on the corresponding mathematical models used to calculate the given electrical power as a function of the EV’s situation on streets and its speed. Then, it is possible to evaluate the EV autonomy, and an accurate approximation can be determined when EV is on a wireless charging road. Even with the citation and comparison between the two studied models, this paper opens some perspectives for energy transmitter tools and tries to explain how renewable energy can help the deployment of this technology.

Connecting organic building blocks by covalent bonds to design porous crystalline networks has led to covalent organic frameworks (COFs), consequently transferring the flexibility of dynamic linkages from discrete architectures to extended structures. By virtue of the library of organic building blocks and the diversity of dynamic linkages and topologies, COFs have emerged as a novel field of organic materials that propose a platform for tailor-made complex structural design. Progress over the past two decades in the design, synthesis, and functional exploration of COFs in diverse applications successively established these frameworks in materials chemistry. The large-scale synthesis of COFs with uniform structures and properties is of profound importance for commercialization and industrial applications; however, this is in its infancy at present. An innovative designing and synthetic approaches have paved novel ways to address future hurdles. This review article highlights the fundamental of COFs, including designing principles, coupling reactions, topologies, structural diversity, synthetic strategies, characterization, growth mechanism, and activation aspects of COFs. Finally, the major challenges and future trends for large-scale COF fabrication are outlined.

KUBÁTOVÁ, Hana. Topologies of the Holocaust in the East Slovak Countryside. Historický časopis, 2021, 69, 4, pp. 601–625, Bratislava. Placing my investigation into the historically multi-ethnic and multireligious small towns and villages of the former Šariš-Zemplín County in eastern Slovakia during the Second World War, I examine ideas and policies associated with civilizing the countryside, as voiced and introduced by Hlinka’s Slovak People’s Party. Building on what is now a growing scholarship on the topographies and topologies of the Holocaust, I reconstruct here how plans and programs to raise living standards in the east of the country, including a policy entitled “caring for the Slovak village,” hastened the further exclusion of local Jews from what had been a joint social space and physical place. Doing so, I manifest how the “beautifying” of Slovak villages included “cleansing” these from the Jews, and how the process, while orchestrated from above, had its own local dynamics. More generally, my work makes a case for an integrated social history of the Holocaust in eastern Slovakia, one that shows how the social and economic “uplifting” was intertwined with the robbing and murdering of local Jews.

Multi-level inverters (MLIs) have been widely used in recent years due to their various advantages in industrial and grid-connected applications. Traditional MLI topologies are being hampered by the rapid surge of renewable energy systems (RES) as a result of performance difficulties such as poor power reliability, an economically unviable structure, and a lack of efficiency. These difficulties are due to the traditional MLI topologies' inability to keep up with the increasing demand for RES. Because of concerns about performance and limitations posed by classic MLI topologies, researchers have found themselves driven to the idea of building innovative hybrid MLI topologies. This study provides a comprehensive analysis of multilevel inverter systems that are wired into the main power supply. Grid-connected inverter types and their configurations are discussed in depth in this review. Diverse multi-level inverter topologies, as well as the different approaches, are divided into various categories and discussed in depth. Additionally, a number of control reference frames for inverters were brought forward for discussion. Furthermore, different inverter control strategies were investigated, followed by a tabular summary of recent developments in the inverter-related literature for the convenience of the readers. Moreover, the recently proposed grid-connected multi-level inverter systems were discussed including their findings and innovations. In conclusion, a brief description of the study's scope was offered and research directions for future studies were provided. [ABSTRACT FROM AUTHOR]

The metal–organic framework (MOF) [Zn(Isa-az-tmpz)]·~1–1.5 DMF with the novel T-shaped bifunctional linker 5-(2-(1,3,5-trimethyl-1H-pyrazol-4-yl)azo)isophthalate (Isa-az-tmpz) was obtained as a conglomerate of crystals with varying degrees of enantiomeric excess in the chiral tetragonal space groups P43212 or P41212. A topological analysis of the compound resulted in the rare 3,6T22-topology, deviating from the expected rtl-topology, which has been found before in pyrazolate-isophthalate-functionalized MOFs using the supramolecular building layer (SBL) approach. 3,6T22-[Zn(Isa-az-tmpz)]·~1–1.5 DMF is a potentially porous, three-dimensional structure with DMF molecules included in the corrugated channels along the a and b-axis of the as synthesized material. The small trigonal cross-section of about 6 × 4 Å (considering the van der Waals surface) prevents the access of N2 and Ar under cryogenic conditions. After activation, only smaller H2 (at 87 K) and CO2 (at 195 K) are allowed for gas uptakes of 2 mmol g–1 and 5.4 mmol g–1, respectively, in the ultramicroporous material, for which a BET surface area of 496 m2·g–1 was calculated from CO2 adsorption. Thermogravimetric analysis of the compound shows a thermal stability of up to 400 °C. [ABSTRACT FROM AUTHOR]

With the development of the global economy, the automobile industry is also developing constantly. In recent years, due to the shortage of environmental energy and other problems, seeking clean energy as the power source of vehicles to replace traditional fossil energy could be one of the measures to reduce environmental pollution. Among them, fuel cell hybrid electric vehicles (FCHEVs) have been widely studied by researchers for their advantages of high energy efficiency, environmental protection, and long driving range. This paper first introduces the topology of common FCHEVs and then classifies and introduces the latest energy management strategies (EMSs) for FCHEVs. Finally, the future trends of EMSs for FCHEVs are discussed. This paper can be useful in helping researchers better understand the recent research progress of EMSs for FCHEVs. [ABSTRACT FROM AUTHOR]

Covid-19 is a disease that can lead to pneumonia, respiratory syndrome, septic shock, multiple organ failure, and death. This pandemic is viewed as a critical component of the fight against an enormous threat to the human population. Deep convolutional neural networks have recently proved their ability to perform well in classification and dimension reduction tasks. Selecting hyper-parameters is critical for these networks. This is because the search space expands exponentially in size as the number of layers increases. All existing approaches utilize a pre-trained or designed architecture as an input. None of them takes design and pruning into account throughout the process. In fact, there exists a convolutional topology for any architecture, and each block of a CNN corresponds to an optimization problem with a large search space. However, there are no guidelines for designing a specific architecture for a specific purpose; thus, such design is highly subjective and heavily reliant on data scientists' knowledge and expertise. Motivated by this observation, we propose a topology optimization method for designing a convolutional neural network capable of classifying radiography images and detecting probable chest anomalies and infections, including COVID-19. Our method has been validated in a number of comparative studies against relevant state-of-the-art architectures. [ABSTRACT FROM AUTHOR]

Modern phylogenetics research is often performed within a Bayesian framework, using sampling algorithms such as Markov chain Monte Carlo (MCMC) to approximate the posterior distribution. These algorithms require careful evaluation of the quality of the generated samples. Within the field of phylogenetics, one frequently adopted diagnostic approach is to evaluate the effective sample size (ESS) and to investigate trace graphs of the sampled parameters. A major limitation of these approaches is that they are developed for continuous parameters and therefore incompatible with a crucial parameter in these inferences: the tree topology . Several recent advancements have aimed at extending these diagnostics to topological space. In this reflection paper, we present two case studies - one on Ebola virus and one on HIV - illustrating how these topological diagnostics can contain information not found in standard diagnostics, and how decisions regarding which of these diagnostics to compute can impact inferences regarding MCMC convergence and mixing. Our results show the importance of running multiple replicate analyses and of carefully assessing topological convergence using the output of these replicate analyses. To this end, we illustrate different ways of assessing and visualizing the topological convergence of these replicates. Given the major importance of detecting convergence and mixing issues in Bayesian phylogenetic analyses, the lack of a unified approach to this problem warrants further action, especially now that additional tools are becoming available to researchers., Competing Interests: Competing interests No competing interest is declared.

Grid-connected converters (GCCs) are used extensively for the integration of DC power sources with AC power sources. However, since it is a complex topic, there are many possibilities for regulating grid-injected currents, as well as different modulation techniques for generating full-bridge PWM voltages. The control techniques are directly related to the type of output filter, as well as to the topology of the converter, since a complex plant can require more sophisticated controllers to keep the system stable, and with good regulation performance. Furthermore, a discussion of the applicability of these converters in weak and very weak grids with high inductance content has recently been growing, which adds a greater degree of complexity to the control structure of the converter. In this brief overview are outlined some topics about topologies, output filters, and control, focusing on the current regulation of grid-connected converters. In addition, a discussion of the main challenges and critical areas in operating on weak and very weak grids is also presented.

The wide-scale adoption and accelerated growth of electric vehicle (EV) use and increasing demand for faster charging necessitate the research and development of power electronic converters to achieve high-power, compact, and reliable EV charging solutions. Although the fast charging concept is often associated with off-board DC chargers, the importance of on-board AC fast charging is undeniable with the increasing battery capacities. This article comprehensively reviews gallium nitride (GaN) semiconductor-based bidirectional on-board charger (OBC) topologies used in both 400 V and 800 V EV applications. Moreover, comparative evaluations of GaN-based bi-directional OBC topologies regarding power conversion losses (conduction loss and soft switching capabilities), power density, implementation considerations, power quality, electromagnetic interference, and reliability aspects have been presented. The status of commercially available GaN power modules, advancements in GaN technology, applicable industry standards, and application requirements for OBCs have been also included in this study. Finally, in light of forthcoming advancements in GaN power transistor technology, this study highlights potential areas of research related to the reviewed topologies. Such research can aid researchers and designers in improving the performance and user experience of electric vehicles, ultimately supporting the widespread adoption of EVs.

Mathematical models are either strategic, simplified, to study global qualitative properties, or tactic, detailed, appropriate for fine quantitative adjustment to reality. When complex systems interact with their medium or undergo parameter perturbations, they can suffer changes of order making qualitative and quantitative studies difficult. Epidemiological processes allow distinguishing between topological and dynamical alterations, and establishing precedence among them. In this essay we approach COVID-19 this way, to separate topological transformations inducing changes of order in the system, from dynamic transformations themselves. We then develop a visual metaphor, a sequence of images to support a stop-motion, allowing distinguishing the stages, identifying and classifying sceneries, and suggest actions to improve the understanding and control, of the pandemic.

Multiphase machines are very convenient for applications that require high reliability. In this two-part survey, the state of the art about fault tolerance in multiphase drives is reviewed. In Part 1, an overview including numerous fault types was presented, along with fundamental notions about multiphase drives. Here, in Part 2, the focus is placed on phase/switch open-circuit (OC) faults in particular, which have received the most attention in the literature. Phase OC failures involve OCs in stator phases or in converter-machine connections, and switch/diode OCs are frequently dealt with similarly or identically. Thanks to the phase redundancy of multiphase drives, their operation can be satisfactorily continued under a certain number of OCs. Nonetheless, the procedure to follow for this purpose is far from unique. For given OC fault conditions, numerous fault-tolerant possibilities can be found in the literature, each of them with different advantages and disadvantages. Moreover, a great variety of methods have also been devised to detect and diagnose phase/switch OC failures so that, as soon as possible, the most appropriate fault-tolerance measures are applied. Thus, given the broad literature about tolerance to phase/switch OC faults in multiphase drives, the survey presented here is expected to be of great interest for the research community and industry. [ABSTRACT FROM AUTHOR]

The paper firstly analyzes the formation mechanism of signal reflection in signal integrity, lists several typical waveforms of signal reflection ,and then puts forward the main measures to eliminate signal reflection. It focuses on the analysis of termination matching and the effective measures to be taken under different topologies, and gives the simulation verification of signal integrity combined with engineering cases.

Transverse flux permanent magnet (TFPM) machines are a potential candidate for direct-drive wind power application due to high torque and power densities. The operating principle of TFPM machines is firstly described with various topologies available in literature, with the placement of magnets as a criterion for the classification of TFPM machine topologies. This review includes characteristics, power factor improvement, cogging torque minimization, material consideration, modelling techniques, and scalability. Different wind turbine concepts with direct-drive machines, control techniques and power converter topologies are also considered in this paper.

Solid-state transfer switch (SSTS) becomes the most crucial technology for electric power transmission, distribution and control system. SSTS is useful in supplying the power to sensitive loads uninterruptedly and critical loads economically and efficiently. However, a few concerns could hamper the effectiveness of SSTS including voltage swell, sag, inappropriate structure, poor power factor and inefficient control methods. Hence, this paper comprehensively surveys the diverse SSTS topologies, applications, operations, issues, and future directions. The SSTS configuration, design, control system, benefits and shortcomings are discussed rigorously. A detailed comparative analysis of various SSTS are carried out concerning topologies, control operations and applications. In line with that, the different control models and schemes are narrated briefly. This paper also highlights existing challenges and issues before providing a few important future prospects to enhance the configuration and efficiency of SSTS. All the key information obtained from this review would be beneficial to the researchers and power system engineers to develop an advanced and efficient SSTS toward future performance enhancement.

There are various ways to derive multilevel converter topologies as pointed out by the author's previous work. This letter proposes a voltage-source generalized multilevel converter topology that unifies several generalized multilevel topologies and also incorporates bidirectional switches. Most of the known multilevel topologies can be derived from this topology and new topologies can also be derived from it. Examples have been given in this letter. This generalized topology helps to understand complicated converter topologies, especially those with bidirectional switches and it can also be used to determine the voltage requirements/ratings of the devices in various topologies. This letter has summarized the rules to derive topologies from this generalized topology and provides experimental results for one of the derived multilevel converter examples. It is expected that new topologies can be inspired or derived from this letter and used for existing and emerging applications, with this letter as a milestone in the research of multilevel converter topologies. [ABSTRACT FROM AUTHOR]

With the development of the global economy, the automobile industry is also developing constantly. In recent years, due to the shortage of environmental energy and other problems, seeking clean energy as the power source of vehicles to replace traditional fossil energy could be one of the measures to reduce environmental pollution. Among them, fuel cell hybrid electric vehicles (FCHEVs) have been widely studied by researchers for their advantages of high energy efficiency, environmental protection, and long driving range. This paper first introduces the topology of common FCHEVs and then classifies and introduces the latest energy management strategies (EMSs) for FCHEVs. Finally, the future trends of EMSs for FCHEVs are discussed. This paper can be useful in helping researchers better understand the recent research progress of EMSs for FCHEVs.

Multi-level inverters (MLIs) have been widely used in recent years due to their various advantages in industrial and grid-connected applications. Traditional MLI topologies are being hampered by the rapid surge of renewable energy systems (RES) as a result of performance difficulties such as poor power reliability, an economically unviable structure, and a lack of efficiency. These difficulties are due to the traditional MLI topologies’ inability to keep up with the increasing demand for RES. Because of concerns about performance and limitations posed by classic MLI topologies, researchers have found themselves driven to the idea of building innovative hybrid MLI topologies. This study provides a comprehensive analysis of multilevel inverter systems that are wired into the main power supply. Grid-connected inverter types and their configurations are discussed in depth in this review. Diverse multi-level inverter topologies, as well as the different approaches, are divided into various categories and discussed in depth. Additionally, a number of control reference frames for inverters were brought forward for discussion. Furthermore, different inverter control strategies were investigated, followed by a tabular summary of recent developments in the inverter-related literature for the convenience of the readers. Moreover, the recently proposed grid-connected multi-level inverter systems were discussed including their findings and innovations. In conclusion, a brief description of the study’s scope was offered and research directions for future studies were provided.

The metal–organic framework (MOF) [Zn(Isa-az-tmpz)]·~1–1.5 DMF with the novel T-shaped bifunctional linker 5-(2-(1,3,5-trimethyl-1H-pyrazol-4-yl)azo)isophthalate (Isa-az-tmpz) was obtained as a conglomerate of crystals with varying degrees of enantiomeric excess in the chiral tetragonal space groups P43212 or P41212. A topological analysis of the compound resulted in the rare 3,6T22-topology, deviating from the expected rtl-topology, which has been found before in pyrazolate-isophthalate-functionalized MOFs using the supramolecular building layer (SBL) approach. 3,6T22-[Zn(Isa-az-tmpz)]·~1–1.5 DMF is a potentially porous, three-dimensional structure with DMF molecules included in the corrugated channels along the a and b-axis of the as synthesized material. The small trigonal cross-section of about 6 × 4 Å (considering the van der Waals surface) prevents the access of N2 and Ar under cryogenic conditions. After activation, only smaller H2 (at 87 K) and CO2 (at 195 K) are allowed for gas uptakes of 2 mmol g–1 and 5.4 mmol g–1, respectively, in the ultramicroporous material, for which a BET surface area of 496 m2·g–1 was calculated from CO2 adsorption. Thermogravimetric analysis of the compound shows a thermal stability of up to 400 °C.

Four new different porous crystalline Cd(II)-based coordination polymers (CPs), i. e., [Cd(mdpt)2]·2H2O (1), [Cd2(mdpt)2(m-bdc)(H2O)2] (2), [Cd(Hmdpt)(p-bdc)]·2H2O (3), and [Cd3(mdpt)2(bpdc)2]·2.5NMP (4), were obtained successfully by the assembly of Cd(II) ions and bitopic 3-(3-methyl-2-pyridyl)-5-(4-pyridyl)-1,2,4-triazole (Hmdpt) in the presence of various benzendicarboxylate ligands, i.e., 1,3/1,4-benzenedicarboxylic acid (m-H2bdc, p-H2bdc) and biphenyl-4,4′-bicarboxylate (H2bpdc). Herein, complex 1 is a porous 2-fold interpenetrated four-connected 3D NbO topological framework based on the mdpt− ligand; 2 reveals a two-dimensional (2D) hcb network. Interestingly, 3 presents a three-dimensional (3D) rare interpenetrated double-insertion supramolecular net via 2D ···ABAB··· layers and can be viewed as an fsh topological net, while complex 4 displays a 3D sqc117 framework. Then, the different gas sorption performances were carried out carefully for complexes 1 and 4, the results of which showed 4 has preferable sorption than that of 1 and can be the potential CO2 storage and separation material. Furthermore, the stability and luminescence of four complexes were performed carefully in the solid state.

Linear machines (LMs) produce linear motion without any intermediate transmission mechanisms, thus the whole electromechanical system has simple structure and its efficiency is high. Because of such merits, linear machines have been studied for a long time and rapidly developed in recent years. Due to the characteristic of open structure, linear machines have more diversity than rotary machines in terms of machine topologies. Accounting for the wide applications of linear machines, e.g. Maglev train, precision machine tools, semiconductor processing device, automatic equipment, logistic transport line, ropeless lifter, compressor, etc., this paper reviews the most applied linear machines including machine topologies, operating principle and features. In addition, the influence of end effects and the corresponding reduction methods are also summarized. Finally, several commercial applications are exemplified.

Splitting of a dc voltage source with two capacitors has been the approach in generating 5-level output voltage with single- and three-phase full-bridge circuits and added bidirectional switch. Associated with this configuration is the problem of voltage imbalance between the splitting capacitors. In addition, the inverter output voltage magnitude is obviously limited to the value of the split input voltage source. Presented in this paper is a unit topology for single-phase 5-level multilevel inverter, MLI. It simply consists of a full-bridge circuit, a capacitor, charge-discharge unit and a dc source. The charge-discharge unit with the capacitor is the interface between the fullbridge and the dc source. The proposed unit cell can generate a 5-level output voltage waveform whose peak value is twice the input voltage value. For higher output voltage level, a cascaded structure of the developed unit cell is presented. Comparing the proposed inverter with CHB inverter and some recent developed MLI topologies, it is found that the proposed inverter configuration generates higher output voltage value, at reduced component-count, than other topologies, for a specified number of dc input voltages. For two cascaded modules, simulation and experimental verifications are carried out on the proposed inverter topology for an R-L load. [ABSTRACT FROM AUTHOR]

Energy shortage and environmental pollution issues can be reduced considerably with the development and usage of electric vehicles (EVs). However, electric vehicle performance and battery lifespan depend on a suitable battery arrangement to meet the various battery performance demands. The safety, reliability, and efficiency of EVs largely depends on the constant monitoring of the batteries and management of battery packs. This work comprehensively reviews different aspects of battery management systems (BMS), i.e., architecture, functions, requirements, topologies, fundamentals of battery modeling, different battery models, issues/challenges, recommendations, and active and passive cell balancing approaches, etc., as compared to the existing works which normally discuss one or two aspects only. The work describes BMS functions, battery models and their comparisons in detail for an efficient operation of the battery pack. Similarly, the work presents a comprehensive overview of issues and challenges faced by BMS and also provides recommendations to address these challenges. Cell balancing is very important for the battery performance and in this work various cell balancing methodologies and their comparisons are also presented in detail. Modeling of a cell balancer is presented and a comparative study is also carried out for active and passive cell balance technique in MATLAB/Simulink with an eight cell battery packcell balancing approach. The result shows that the active cell balancing technique is more advantageous than passive balancing for electrical vehicles using lithium-ion batteries.

Weaving of organic compounds on the molecular level is an intriguing challenge and promises to provide materials that combine high elasticity with strength and fracture toughness. Yet, the formation of crossing points between molecular threads in defined and regular distances to create an interwoven network is not trivial. To date, only a few examples of wholly organic weaves have been reported. Within this review we present the different strategies that enabled their formation and highlight the structural features of the obtained nanostructured materials. We expect these pioneering studies to pave the way to many more organic molecular weaves with more and more sophisticated topologies and exquisite mechanical properties.

DC collection network offers an attractive alternative to AC network for photovoltaic, as it avoids the charging current issues and reduces the size and weight. Variable voltage gain DC/DC converters play an important role in DC collection network. Two topologies suitable for photovoltaic DC collection are studied. Boost and LLC converter and active clamp isolated full-bridge boost converter are two converters with high and variable voltage conversion ratio suitable for the photovoltaic system. This work investigates the two converters comprehensively. The topologies are analysed so as to summarise and compare the characteristic of the converters. Soft switching condition is compared to help extend the zero voltage switching range. Voltage and current stress of the two converters are calculated. Loss comparison is made with the theoretical analysis. Advantages and disadvantages are summarised to get a deep insight into their application field.

DC collection network offers an attractive alternative to AC network for photovoltaic, as it avoids the charging current issues and reduces the size and weight. Variable voltage gain DC/DC converters play an important role in DC collection network. Two topologies suitable for photovoltaic DC collection are studied. Boost and LLC converter and active clamp isolated full-bridge boost converter are two converters with high and variable voltage conversion ratio suitable for the photovoltaic system. This work investigates the two converters comprehensively. The topologies are analysed so as to summarise and compare the characteristic of the converters. Soft switching condition is compared to help extend the zero voltage switching range. Voltage and current stress of the two converters are calculated. Loss comparison is made with the theoretical analysis. Advantages and disadvantages are summarised to get a deep insight into their application field. [ABSTRACT FROM AUTHOR]

Abstract Hybrid Energy Storage System (HESS) can well solve the problems faced by alternative single energy storage system in terms of meeting the needs of high specific power and high specific energy simultaneously for plug-in hybrid electric vehicles (HEVs). A HESS containing battery and ultracapacitor (UC) has drawn much attention. However, there have been relatively few reviews on its structures and energy management strategies (EMSs). Based on the summary and analysis from the existing publications, this paper reviews and discusses the structures and the EMSs of HESSs comprised of battery and UC. Focusing on energy management research, a detailed discussion of rules-based control algorithms, optimization-based control algorithms and intelligent-based control algorithms is presented. Several typical implementations and applications are presented in detail, and a comparative evaluation of these methods can help researchers select the appropriate method to develop EMSs for HESSs. Finally, the paper also highlights a number of key factors and challenges, and presents the possible recommendations for the development of big data and machine learning-based algorithm for the energy management of the HESSs. [ABSTRACT FROM AUTHOR]

Three microporous Zn coordination polymers, [Zn 3 (OH) 2 (TCBA)(4,4′-bpy)]·5.5H 2 O ( 1 ), [Zn 3 (OH) 2 (TCBA)(4,4′-bpy) 1.5 ]·5H 2 O ( 2 ), and [Zn 4 (TCBA) 2 (4,4′-bpy) 2 (H 2 O) 8 ]·11H 2 O ( 3 ) (H 4 TCBA = 3,4,5-tris(carboxymethoxy)benzoic acid, 4,4′-bpy = 4,4′-bipyrdine), have been hydrothermally synthesized and structurally characterized. 1 presents an uncommon 2-nodal (4,10)-connected network with {3·4 5 } 2 {3 4 ·4 12 ·5 10 ·6 14 ·7 3 ·8 2 } topology; 2 can be described as a 2-nodal (3,8)-connected tfz-d net with the symbol of {4 3 } 2 {4 6 ·6 18 ·8 4 }, both networks are constructed from hexameric [Zn 6 (µ 3 -OH) 4 ] 8+ clusters. While 3 shows an interesting 4-nodal (3,3,3,4)-connected network with {8·10·12} 2 {8·10 2 } 2 {8 4 ·10·12} topology. Complexes 1–3 all own 3-D frameworks with 1-D channels, and in 1–3 lattice and/or coordinated water molecules occupy the channels, especially in 3 Zn-bipy chains reside in the channels together with water molecules. Double helical chains can be observed in complex 2 ; and single helix chains exist in complexes 1 and 3 . Furthermore, the thermal stabilities and photophysical properties of complexes 1–3 were also investigated. [ABSTRACT FROM AUTHOR]

The use of power electronic converters is essential for the operation of Switched Reluctance Machines (SRMs). Many topologies and structures have been developed over the last years considering several specific applications for this kind of machine, improving the control strategies, performance range, fault-tolerant operation, among other aspects. Thus, due to the great importance of power electronic converters in such applications, this paper is focused on a detailed review of main structures and topologies for SRM drives. The proposed study is not limited to the classic two-level power converters topologies dedicated to the SRMs; it also presents a review about recent approaches, such as multilevel topologies and based on impedance source network. Moreover, this review is also focused on a new class of topologies associated to these machines, namely the ones with fault-tolerant capability. This new category of topologies has been a topic of research in recent years, being currently considered an area of great interest for future research work. An analysis, taking into consideration the main features of each structure and topology, was addressed in this review. A classification and comparison of the several structures and topologies for each kind of converter, considering modularity, boost capability, number of necessary switches and phases, integration in the machine design, control complexity, available voltage levels and fault-tolerant capability to different failure modes, is also presented. In this way, this review also includes a description of the presented solutions taking into consideration the reliability of the SRM drive.

Subject of Research. The paper considers one of the possible approaches to the study of Ethernet networks by simulating them in the OMNeT ++ environment with the use of the INET framework. The possibility of studying network models is shown in both the step-by-step execution mode and the mode of obtaining generalized statistical characteristics of their operation. Method. When presenting the proposed approach, the method of sequential complication of network models was used, taking into account the features of existing standard protocols and network implementations. The simplicity of the proposed approach is shown, which is based on a wide range of ready-made components for the description of various network elements within the INET framework. This fact gives the possibility to form quite complex network models by means of only the graphic editor and the built-in NED network description language. A brief description of INET framework main components is given that makes it possible to form the structure of the network under research in the graphical editing mode. Main Result. The paper presents technique for creation of network simulation models with a sufficiently detailed description of the main modeling stages. The simplest methods for launching the network model into work and analyzing the results are considered. The work shows the possibility of creating custom component modules in the INET framework projects, which, being ready-made components, can be used in models of more complex network structures. Based on the generated approach, models were built of both basic and mixed Ethernet topologies that gave the possibility to carry out a sufficiently detailed analysis for each of these topologies. Practical Relevance. The described toolkit makes it possible to carry out research on the justification of design solutions for design of distributed computer networks, as well as for creation of tools supporting the automated design of infocommunication systems and networks.

Abstract—Matrix Converter (MC) is a modern direct AC/AC electrical power converter without dc-link capacitor. MC is operated in four quadrant, assuring a control of the output voltage, amplitude and frequency. The matrix converter has recently attracted significant attention among researchers and it has become increasing attractive for applications of wind energy conversion, military power supplies, induction motor drives, etc. Recently, different MC topologies have been proposed and developed which have their own advantages and disadvantages. Matrix converter can be classified as direct and indirect structures. The direct one has been elaborated in previous work. In this paper the indirect MCs are reviewed. Different characteristics of the indirect MC topologies are mentioned to show the strengths and weaknesses of such converter topologies.

Connecting organic building blocks by covalent bonds to design porous crystalline networks has led to covalent organic frameworks (COFs), consequently transferring the flexibility of dynamic linkages from discrete architectures to extended structures. By virtue of the library of organic building blocks and the diversity of dynamic linkages and topologies, COFs have emerged as a novel field of organic materials that propose a platform for tailor-made complex structural design. Progress over the past two decades in the design, synthesis, and functional exploration of COFs in diverse applications successively established these frameworks in materials chemistry. The large-scale synthesis of COFs with uniform structures and properties is of profound importance for commercialization and industrial applications; however, this is in its infancy at present. An innovative designing and synthetic approaches have paved novel ways to address future hurdles. This review article highlights the fundamental of COFs, including designing principles, coupling reactions, topologies, structural diversity, synthetic strategies, characterization, growth mechanism, and activation aspects of COFs. Finally, the major challenges and future trends for large-scale COF fabrication are outlined.