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Ulcerative Colitis(UC) is a chronic intestinal inflammation affecting the intestines, yet its underlying causes remain unclear. In recent decades, the global prevalence of UC has been on the rise, leading to an increasing demand for therapeutic drugs with minimal side effects. Huan Kui Le (HKL), a traditional Chinese medicine compound, has demonstrated promising efficacy when combined with Lactobacillus acidophilus (Lac.) for UC intervention. However, the precise therapeutic mechanism of this combination remains unknown. The study focused on understanding the mechanisms of UC by examining the effects of Lac. and HKL (LH) treatment. The outcomes discovered that the disruption of gut microbiota, triggered by the activation of the NLRP3 inflammasome, plays a crucial role in UC development. This disruption exacerbates UC symptoms by causing disturbances in inflammatory cytokines and mucosal permeability. We investigated the dynamic changes following the application of this treatment using 16S rRNA sequencing, HE, WB, IHC, and ELISA. Compared with the UC group, LH treatment reduced colon pathological injury, improved colon length, and decreased IL-1 β serum levels. Furthermore, it restored the expression of TJs and preserved mucosal barrier integrity. LH treatment also mitigated colon injury by attenuating the expression of pyroptosis-related genes and proteins, such as NLRP3 and Caspase-1. Additionally, LH treatment altered the gut microbiota's microecology, characterized by a reduction in pathogenic bacteria abundance like Escherichia-shigella and an increase in beneficial bacteria abundance like Akkermansia and Erysipelatoclostridium. Overall, our findings indicate that LH therapy may be associated with intestinal barrier repair, inflammasome inhibition, and gut microbiota regulation, suggesting its potential as a UC treatment.

The sugar content in watermelon significantly influences its flavor. To understand the sugar accumulation pattern in small-fruited watermelon and identify candidate genes involved in sugar synthesis and conversion, we measured the sugar content (sucrose, fructose, and glucose) at five developmental stages: 10d, 16d, 22d, 28d, and 34d post-pollination. Two watermelon varieties with the largest sugar content difference at 28d post-pollination (high-sugar G38-28 and low-sugar 482276-28) were selected for transcriptome sequencing. Differentially expressed genes (DEGs) were validated using RT-qPCR. Additionally, the sugar contents of three commercial varieties (‘Su Meng NO.5’, ‘Su Meng NO.6’, ‘Su Meng NO.7’) and their parents were compared at five stages. Results showed glucose and fructose levels peaked between 22d and 28d, followed by a decrease, while sucrose content continuously increased. F1 hybrids exhibited glucose and sucrose trends similar to their paternal parent and fructose trends similar to their maternal parent. Transcriptome sequencing identified 9337 DEGs (5072 upregulated and 4265 downregulated). Gene Ontology analysis highlighted overrepresentation in categories such as pectinase and oxidoreductase activity. KEGG analysis identified 12 DEGs involved in sugar synthesis and conversion pathways, including phenylpropanoid biosynthesis and pentose and glucuronate interconversions. RT-qPCR validation corroborated the transcriptome data. These findings explain the distinct sugar accumulation patterns in G38-28 and 482276-28 at the transcriptional level, offering insights for genetic breeding and regulation of key sugar-related genes in watermelon.

Cellular therapy holds immense promise to remuscularize the damaged myocardium but is practically hindered by limited allogeneic sources of cardiac-committed cells that engraft stably in the recipient heart after transplantation. Here, we demonstrate that the pericardial tissue harbors myogenic stem cells (pSCs) that are activated in response to inflammatory signaling after myocardial infarction (MI). The pSCs derived from the MI rats (MI-pSCs) show in vivo and in vitro cardiac commitment characterized by cardiac-specific Tnnt2 expression and formation of rhythmic contraction in culture. Bulk RNA-seq analysis reveals significant upregulation of a panel of genes related to cardiac/myogenic differentiation, paracrine factors, and extracellular matrix in the activated pSCs compared to the control pSCs (Sham-pSCs). Notably, we define MyoD as a key factor that governs the process of cardiac commitment, as siRNA-mediated MyoD gene silencing results in a significant reduction of myogenic potential. Injection of the cardiac-committed cells into the infarcted rat heart leads to long-term survival and stable engraftment in the recipient myocardium. Therefore, these findings point to pericardial myogenic progenitors as an attractive candidate for cardiac cell-based therapy to remuscularize the damaged myocardium.

Transient stability assessment (TSA) plays a pivotal role in guiding power grid risk control strategies. However, it faces challenges when dealing with complex multi-graph inputs generated by pre-fault, fault occurrence, and post-fault states. Meanwhile, most previous research studies neglected the assessment of the transient stability level. To address this, we propose a multi-task transient stability assessment (MTTSA) approach. In MTTSA, we introduce a multi-graph sample and aggregate-attention network (GraphSAGE-A) designed to capture stability features even amidst topology changes. A multi-head attention mechanism and local normalization method are adopted for a better extraction of the global and contextual information. Additionally, we introduce a quantified transient stability risk index considering the transient stability boundary and incorporate a multi-task dense structure to enhance MTTSA’s performance. Empirical tests, under changing operating conditions, conducted on the IEEE 39-bus system showcase a significant performance improvement with the proposed MTTSA method.

Abstract Background Hypospadias is one of the most prevalent urogenital malformations in clinic. However, some hypospadias may have a more complex disorder of sex development. Usually, hypospadias in these patients is severe. Among them, the 46,XX male sex reversal syndrome is a rare disorder of sex development, and this may be the main reason for this type of hypospadias being difficult to repair. Case presentation We present a Han nationality 19-year-old male with failure of repeated repair of hypospadias. No sperm was found on semen analysis. Lingual mucosal graft was carried out for this patient. It still did not succeed after using lingual mucosal graft repair. Karyotype analysis of this patient confirmed 46,XX karyotype. Conclusion Hypospadias with 46,XX male sex reversal syndrome is hard to repair. Chromosome karyotype examination in patients with hypospadias is suggested. Genetic testing is recommended. In the future, further research is needed on the pathogenesis of disease and how to treat and prevent it.

Due to high greenhouse gas emissions, countries worldwide are stepping up their emission reduction efforts, and the global demand for new, carbon-free fuels is growing. Ammonia (NH3) fuels are popular due to their high production volume, high energy efficiency, ease of storage and transportation, and increased application in power equipment. However, their physical characteristics (e.g., unstable combustion, slow flame speed, and difficult ignition) limit their use in power equipment. Based on the structural properties of the power equipment, NH3 fuel application and emissions characteristics were analyzed in detail. Combustion of NH3 fuels and reduction measures for NOx emissions (spark plug ignition, compression ignition, and gas turbines) were analyzed from various aspects of operating conditions (e.g., mixed fuel, fuel-to-exhaust ratio, and equivalence ratio), structure and strategy (e.g., number of spark plugs, compression ratio (CR), fuel injection, and ignition mode), and auxiliary combustion techniques (e.g., preheating, humidification, exhaust gas recirculation, and secondary air supply). The performance of various NH3 fuel cell (FC) types was analyzed, with a focus on the maximum power achievable for different electrolyte systems. Additionally, the application and NOx emissions of indirect NH3 FCs were evaluated under flame and catalytic combustion conditions. The system efficiency of providing heat sources by burning pure NH3, anode tail gas, and NH3 decomposition gas was also compared. Based on a comprehensive literature review, the key factors influencing the performance and emissions of NH3-powered equipment were identified. The challenges and limitations of NH3-powered equipment were summarized, and potential strategies for improving efficiency and reducing emissions were proposed. These findings provide valuable insights for the future development and application of NH3 FCs.

Based on the structure of natural nacres, laminated metal materials have been successfully developed to possess desirable mechanical properties for diverse engineering applications. These heterostructured (HS) laminates consist of layers with different mechanical performances, resulting in asynchronous deformation and intricate stress/strain partitioning behavior. These distinctive phenomena are crucial in achieving the strength-ductility synergy of HS laminates. Nonetheless, further investigations are imperative to gain a comprehensive understanding of local stress and strain evolutions during deformation, and to thoroughly explore the influence of stress/strain partition on the mechanical behavior of the HS laminates. This study utilized the conventional mechanism-based strain gradient (CMSG) plasticity theory to conduct finite element simulations. The tensile deformation of HS laminate comprising nanostructured (NS) bronze and coarse-grained (CG) copper layers was simulated as a benchmark. The simulation results revealed the following: (1) Stress partition and stress transfer between the layers occur during deformation and are influenced by the layer thickness; (2) Both strain partition and strain banding exist in the HS laminates with relatively thinner layers, and the formation of dispersed strain bands is related to the plastic strain gradient; (3) Heterogeneous deformation promotes strain delocalization and strain hardening, consequently leading to improved uniform elongation. This study provides valuable insights into the significant effect of stress/strain partition on the strength-ductility synergy of HS laminates from the perspective of constitutive modeling.

Value for Money (VfM) has been used as a critical criterion for evaluating Public-Private Partnerships (PPPs), a popular procurement strategy for delivering infrastructure assets. However, there is a tendency for prevailing VfM techniques (e.g., Public Sector Comparator, PSC) to focus on obtaining cost savings rather than value per se. Despite the criticisms of the PSC and its alternatives for assessing VfM, there remains no research comparing decision-making methods for procuring transport infrastructure projects. In this instance, the upshot has been the public sector's inability to safeguard and deliver VfM to their taxpayers. Against this backdrop, we systematically review the VfM assessment literature to understand the effectiveness (e.g., strengths, weaknesses, opportunities, and threats) of prevailing approaches used to determine the ‘value’ of transport projects. In light of our review, we propose and introduce the concept of the ‘onion’ architecture to improve the decision-making practice of PPPs, which comprises four systematic future research directions and policy implications. To this end, our paper provides a platform for developing new procurement paradigms that can be used to future-proof infrastructure assets.

This study establishes and verifies the finite element models (FEM) of MSCCJs to analyze the mechanical performance of modular steel–concrete composite joints (MSCCJs) under monotonic static load without considering the floor slab composite effect (FSCE). Subsequently, 12 MSCCJ models incorporating the FSCE are constructed using ABAQUS. The study evaluates the effects of varying column axial compression ratios (n = 0.15, 0.25, 0.4, 0.6), floor width (w = 800, 1200 mm), floor thickness (t = 90, 110, 120 mm), and floor reinforcement ratio (r = 6 %, 8 %, 12 %) on the bending moment, initial stiffness (k0), ductility, and stress transfer of the joints. The results indicated that as n increases, the shear stress concentration in the joint core module (JCM) and the steel framework at the lower column end become more pronounced. Concurrently, the bearing moment and k0 of the joint also increase. However, once n surpasses 0.4, the joint's plastic properties diminish upon damage. With an increment in w, the k0 and ductility deformation of the joint remain stable and then decline. At w = 1000 mm, the joint's bearing capacity, stress distribution, and deformation performance reach their optimum. Since it significantly impacts stress distribution, its effect on the joint's mechanical performance is minimal. Lastly, the value of r enhances the ductility of MSCCJs and the stress concentration in the reinforcement. It is advisable to maintain r between 1.1 % and 1.7 %.

LLC resonant converters have been widely used in DC/DC conversion because of their high efficiency. However, the converters are highly nonlinear, making it hard to use typical linear control methods. This paper proposes a disturbance-observer-based control approach, which achieves better performance compared with the conventional PI controller. First, according to the extended describing function (EDF) method, the small-signal model of the phase-shift LLC resonant converter is established, which is further simplified to a third-order system. Then, the disturbance-observer-based control is presented, which incorporates a disturbance observer (Dob) to estimate the uncertain effects resulting from external disturbances, circuit parameters variation and model mismatch, and compensate for them in a feedforward way. The main advantage of this control structure is that it can improve the stability and dynamic response simultaneously, where the Dob optimizes the dynamic responses and the PI controller is designed to satisfy the stability requirement. Finally, a 600 W simulation model is built in MATLAB/Simulink to verify the proposed control method, whose superiority over the classic PI controller is proved by the simulation results.

In the urban distribution network, due to the wide application of underground cables, the traditional resonant grounding system has gradually been unable to match the increasing fault current amplitude, real-time compensation and harmonic component compensation requirements. With the continuous advancement of reliable power electronics technology, flexible grounding systems (FGS) based on controllable converters are receiving more attention. Whether it is a traditional grounding system or a flexible grounding system, when a single-phase grounding fault occurs in the power grid, in order to ensure the safety of the power grid, it is necessary to accurately locate the fault in the system. However, how to apply traditional location methods to flexible grounding systems and high-resistance grounding faults is a challenge. In this paper, a new fault location method combining transient mutation and dynamic time warping (DTW) algorithm is proposed. The transient mutation is detected and used for the primary selection of the fault interval firstly. And then, the dynamic time warping algorithm determines the difference between the intervals, and the specific fault location is finally calculated and identified. The verification results based on MATLAB/Simulink prove the rationality and effectiveness of the proposed method.

Article highlights A Markov model of multi-modal hierarchical spatial states is created. The analytical expression of comprehensive availability for the reliability index of the prediction device is derived. The CPU module failure rate threshold for intelligent production testing is amended. A theoretical basis for determining the type of key modules to be employed in field service installations is provided. The rationality and accuracy of the prediction model are verified by comparing the actual working conditions.

The mechanical resistance of plant leaves to herbivores and physical disturbances have a lasting legacy impact on leaf-litter decomposition rates and nutrient leaching. However, in the past, leaf mechanics were seldom considered as key factors in regulating ecological processes related to leaf-litter decomposition. In this paper, we explored the physical strength traits of leaves, which are essential components of plant functional traits. These traits are primarily manifested through three mechanical properties: force to punch, force to tear, and work to shear. We discuss their potential applications in order to better understand trait-based factors influencing leaf-litter decomposition as well as other ecological processes. Their ecological connections and distinctions from other widely discussed plant functional traits relevant to decomposition processes were also addressed. By conducting an extensive literature survey, we further showed the importance and irreplaceability of leaf physical strength traits as potential predictors of leaf-litter decomposability compared with commonly measured plant chemical traits (e.g., carbon, nitrogen, and lignin). Recognizing leaf mechanics as vital yet previously overlooked determinants of ecological processes governing leaf-litter decomposition, we propose incorporating this set of traits into existing predictive models to improve the explanatory capability of plant species traits in regulating leaf-litter decomposition processes.

At present, multi-fuel cell system (MFCS) is used to meet the high-power requirement, when a single stack fuel cell system is not sufficient. For the issue of non-optimal solutions in the low power range of multi-stack systems, the scheme of downgrade strategy power allocation for multi-stack systems is implemented by combining with Hydrogen consumption fitting curve and Lagrange function to solve condition constraint. The analytical solution of the scheme allows the power allocation of the n-dimensional system to be performed, which is expressed as an expression for the power allocation, hydrogen consumption, and the intersection of hydrogen consumption of the multi-stack system and the downgraded system. The solution meets the load power demand and better optimizes the low power output. The experimental results also verified the effectiveness of the optimized scheme by four 1kW proton exchange membrane fuel cell (PEMFC) systems.

Abstract This paper presents a hierarchical voltage balance control method for a hybrid modular multi‐level converter based on half‐bridge submodule and dual‐capacitor submodule. This voltage balancing method reduces the control complexity of the existing voltage balancing method of the central controller but does not significantly increase the control complexity of the submodule controller. In dual‐capacitor submodule, only some logic operations are added. Furthermore, the proposed method reduces the hardware requirements and communication data between the submodule and central controllers. The reduced hardware requirements refer to the hardware circuits used to implement communication functions. The proposed method is also applicable to multi‐level converter, which only includes half‐bridge submodules, but requires two adjacent half‐bridge submodules to use the same submodule controller. Simulation and experimental results validate the feasibility and effectiveness of the proposed hierarchical voltage balance control.

Improving the operating conditions can enhance the output performance of PEMFCs based on Ammonia decomposition gas as fuel (Ammonia–Hydrogen fuel cell). Therefore, in this study, a 3-dimensional non-isothermal numerical model was established to study the gas–heat–water distribution of Ammonia–Hydrogen fuel cell under different operating conditions, and the performance improved by operating conditions is analyzed through regional quantification, and then optimize the operating conditions for improving performance. The research results show that increasing the working pressure, gas humidity and nitrogen adsorption can improve the output performance of the fuel cell effectively. Under low-pressure operating conditions, increasing the unit pressure can increases the output performance by 80%; under low-humidity operating conditions, increasing the relative humidity by 0.15 can increases the output performance by 8%; under low-hydrogen content operating conditions, increasing the mole fraction of hydrogen by 5% through nitrogen adsorption can increases the output performance by 10%. Along the flow direction, the molar concentration distribution characteristics of reactant gas is opposite to the change trend of membrane water content, which is closely related to the reaction rate; the overall change trend of heat is consistent with the water content of the membrane, but the hot spot value at the outlet has a downward trend with the strengthening of the reaction conditions and the continuous increase of the load. When operating conditions changes, the variation trend of the regional total output is different, and the maximum value of the total output varies from the operating conditions. Optimizing the operating conditions can make it possible to achieve the output performance based on pure hydrogen as fuel.

Modular multilevel DC transformers(MMDCTs) have become a research focus in DC grids with different voltage levels based on their advantages of strong expansibility and high voltage levels. It is necessary to apply pre-charging control to avoid inrush currents generated by the charging of the capacitor and the inrush current of the transformer during the starting process. A fast pre-charging strategy based on compound frequency control is proposed in this study. The independent control of the direct current component and intermediate frequency component is used to realize simultaneous charging of the primary and secondary sides. The primary side adopts double closed-loop control, whereas the secondary side adopts variable-step phase-shift peak current control, which resolves the contradiction between the charging speed and inrush current. Additionally, a quantitative comparative analysis of various pre-charging strategies was conducted. The effectiveness and feasibility of the proposed pre-charging strategy are verified through simulations and experiments. The results demonstrate that the magnitude of the inrush current and charging time were effectively controlled by the proposed method.

With the development of fuel cells, the demand for high-power fuel cells has gradually increased, but the multi-stack fuel cell system(MFCS) has received wide attention due to the existing technical barriers. The optimal efficiency of the multi-stack fuel cell system is the target, and the power distribution point of the multi-stack fuel cell is obtained by combining the KKT condition. Equipped with the recursive gradient correction method, the online identification of the optimal efficiency of the system is realized. The results are compared with the average distribution and Daisy-chain methods, and the online identification algorithm results in the highest optimal efficiency and the lowest hydrogen consumption. It was validated on two 1kW air-cooled fuel cell systems.

Simulating the mechanical behavior of cellular materials stands as a pivotal step in their practical application. Nonetheless, the substantial multitude of unit cells within these materials necessitates a considerable finite element mesh, thereby leading to elevated computational expenses and requisites for formidable computer configurations. In order to surmount this predicament, a novel and straightforward equivalent calculation method is proposed for the computation of mechanical properties concerning both random and ordered hyper-elastic cellular materials. By amalgamating the classical finite element approach with the distribution attributes of cells, the proposed equivalent calculation method adeptly captures the deformation modes and force-displacement responses exhibited by cell materials under tensile and shear loads, as predicted through direct numerical simulation. This approach reflects the deformation characteristics induced by micro-unit cells, elucidates an equivalent principle bridging cellular materials and equivalent materials, and substantially curtails exhaustive computational burdens. Ultimately, this method furnishes an equivalent computational strategy tailored for the engineering applications of cellular materials.

Static frequency converters (SFCs) are very important for starting the connection of synchronous capacitors to the power grid, which is beneficial for ensuring the impact of electric vehicle connection on the inertia of the power grid. In the traditional sensorless initial rotor position detection method, the signal-to-noise ratio of the induced voltage at the machine terminal is small, making it difficult to accurately extract the rotor position. In this study, a reliable initial position detection method for a sensorless-controlled synchronous machine drive is proposed. A step excitation voltage was applied to the excitation circuit before the motor was started, and the three-phase induction voltage at the terminals was sampled in real time. The sampling signal was processed in two ways: digital filter processing and stator flux calculation. The accuracy of the initial rotor position is determined by comparing the differences between the two results. This algorithm does not depend on additional hardware circuits and has fewer setting parameters; therefore, it is easy to apply in engineering applications. Finally, a comparative experiment was conducted using a real-time digital system (RTDS) to verify the feasibility and effectiveness of the proposed method. The proposed rotor position detection method can effectively improve the detection reliability and ensure the start-up reliability of SFCS.

With the development of power grid technology, a large number of constant power loads (CPL) are introduced into the power grid system. The negative damping characteristic of CPL poses a great challenge to the stability of power grid under the condition of large signal disturbance. This paper focuses on the large signal stability and dynamic response characteristics of DC microgrid with CPL. The mixed potential function (MPF) method is adopted to model the large signal characterstic of load converter controlled by the traditional PI control strategy and the new virtual DC motor (VDM) control strategy. The large signal stability criteria and the asymptotic stability region of the DC microgrid system under the two control strategies are derived. The dynamic response characteristics of the DC microgrid are compared under three large signal operation conditions of the load step, load linear change and the load fault. The results show that VDM control strategy can effectively improve dynamic response characteristics of the DC microgrid system compared with those of PI control, and enhance the stability and anti-interference ability of the DC microgrid system.

Abstract As for the voltage‐controlled voltage sources converter (VSC), the inner current loop of dual closed‐loop control is equivalent to a virtual impedance, which provides effective damping for the system. However, the time delay caused by computation and transmission becomes increasingly prominent in the low‐pulse‐ratio cases, which not only limits the achievable bandwidth, but also reduces the stability of the current loop. This paper proposes an enhanced control strategy for current loop by adding the feedback of computation delay into the current controller, to significantly widen the stability region and control bandwidth, and increase the active damping. The parameter design of the current controller is presented based on discrete‐time root locus. Subsequently, the voltage controller is directly deduced in the discrete‐time domain, which eliminates the poles/zeros deviation caused by discretization. The accurate delay compensation is realized by pole‐zero cancellation, thus avoiding the additional phase compensation for fundamental and harmonic frequencies. Simulation and experimental results validate the effectiveness of the enhanced dual‐loop control strategy.

Abstract Background Cellular dedifferentiation is a regenerative prerequisite that warrants cell cycle reentry and appropriate mitotic division during de novo formation of cardiomyocytes. In the light of our previous finding that expression of injury-responsive element, Wilms Tumor factor 1 (WT1), in pericardial adipose stromal cells (ADSC) conferred a compelling reparative activity with concomitant IL-6 upregulation, we then aim to unravel the mechanistic network that governs the process of regenerative dedifferentiation after ADSC-based therapy. Methods and results WT1-expressing ADSC (eGFP:WT1) were irreversibly labeled in transgenic mice (WT1-iCre/Gt(ROSA)26Sor-eGFP) primed with myocardial infarction. EGFP:WT1 cells were enzymatically isolated from the pericardial adipose tissue and cytometrically purified (ADSCgfp+). Bulk RNA-seq revealed upregulation of cardiac-related genes and trophic factors in ADSCgfp+ subset, of which IL-6 was most abundant as compared to non-WT1 ADSC (ADSCgfp−). Injection of ADSCgfp+ subset into the infarcted hearts yielded striking structural repair and functional improvement in comparison to ADSCgfp− subset. Notably, ADSCgfp+ injection triggered significant quantity of dedifferentiated cardiomyocytes recognized as round-sharp, marginalization of sarcomeric proteins, expression of molecular signature of non-myogenic genes (Vimentin, RunX1), and proliferative markers (Ki-67, Aurora B and pH3). In the cultured neonatal cardiomyocytes, spontaneous dedifferentiation was accelerated by adding tissue extracts from the ADSC-treated hearts, which was neutralized by IL-6 antibody. Genetical lack of IL-6 in ADSC dampened cardiac dedifferentiation and reparative activity. Conclusions Taken collectively, our results revealed a previous unappreciated effect of IL-6 on cardiac dedifferentiation and regeneration. The finding, therefore, fulfills the promise of stem cell therapy and may represent an innovative strategy in the treatment of ischemic heart disease.

The active compensation device, between the distribution network’s neutral point and the ground, compensates for the single-phase short-circuit current. And the T-type three-level circuit is a possible scheme for compensation devices. This paper proposes the T-type average model based on the above topology, with a controlled voltage/current source, regardless of modulation or control methods. Compared with the two-level converter topology, the three-level converter topology improves the rated voltage stress, with few switching devices’ requirements. The modeling and simulation indicate that the T-type’s average model is identical to its switch model. And the T-type three-level converter can achieve the desired active compensation.

Direct current (DC) solid-state transformers based on modular multilevel converters (MMC-DCSSTs) have wide application prospects in DC transmission and distribution systems. However, after starting such a system, the normal operation of its MMC-DCSST​ may generate relatively large inrush and magnetizing currents on the primary and secondary sides. In this study, a soft-starting scheme for MMC-DCSSTs, which is divided into the primary-side and secondary-side charging stages, has been designed to limit these currents before the system reaches the normal operation stage. The effectiveness of the proposed method is validated experimentally, and the reliability of MMC-DCSSTs can be improved with the controllable currents.

In high-powered application scenarios, a multi-stack fuel cell system (MFCS) could have advantages such as higher robustness, lifetime, and reliability than a single-stack fuel cell system. In particular, MFCS could maintain a high efficiency and increase system redundancy by power configuration between subsystems. In order to reduce the operational expenses for systems, a reasonable power management strategy is necessary to minimize the hydrogen consumption of MFCS. First, the power-hydrogen consumption curve of the single-stack fuel cell system is discretized from experimental measurements. Next, the discrete data are reassembled by the inverse derivation of the dynamic programming method to produce a minimum solution for the hydrogen consumption in the output power range. It is found that the strategy varies depending on activated state On or Off. Finally, two power allocation strategies are developed and modeled in a lookup-table block considering the activated state. The optimal stack output power strategy is analyzed with four stacks. The results indicate that the hydrogen consumption is smaller and more efficient than the other allocation strategies. It can respond to the load demand with a high efficiency sooner than the average strategy.

Amidoxime functionalized chitosan (AC) was recommended as a chelator for uranium sequestration in vivo in this study, and the structure-activity relationship was also explored. Compared with ZnNa3-DTPA, which was a commercial uranium mobilization drug, AC exhibited excellent biocompatibility and uranium removal efficiency, whether by injection or orally, which could reduce the amounts of uranium deposited in kidneys and femurs by up to 43.6% and 32.3%. In particular, ACs still possessed the ability to mobilize uranium in vivo even if administration was delayed for 72 h.

In organic light-emitting diodes, positive and negative charge carriers mostly migrate at different rates. This could result in excitons formed in the EML often migrating to the vicinity of the hole transport layer and the electron transport layer. To address this, it is important to design high-quality multi-resonance hosts that can balance the migration rate of carriers. Here, we report two newly developed multi-resonance hosts, m-ICzPBI and o-ICzPBI. The hosts contain an indolo[3,2,1-jk]carbazole (ICz) motif, which functionalized as either a donor or an acceptor unit. The hosts exhibit extremely high molecular rigidity and thermal stability. Devices A and B were constructed using FIrpic as a phosphorescent emitter with m-ICzPBI or o-ICzPBI as a host. Device A achieved high maximum values of EQE, PE and CE of 13.4%, 24.8 lm W−1 and 31.6 cd A−1, respectively, and low efficiency roll-off at 5000 cd m−2 of 8.6%, 10.6 lm W−1 and 20.3 cd A−1, respectively.

To study the strengthening effect of carbon fiber composite materials (CFRP) on recycled concrete columns subjected to different levels of seismic damage, four column specimens were designed for pseudo-static tests. The four specimens were categorized as non-destructive without strengthening (prototype), non-destructive strengthening, medium seismic damage strengthening, and severe seismic damage strengthening based on the replacement rate of recycled aggregates and the level of seismic damage. The characteristics of the deformation damage and seismic performance indicators of each specimen were compared and analyzed. The results were verified on the OpenSees platform. A decrease was observed in the initial stiffness of the seismically damaged recycled concrete column specimens strengthened with CFRP, while the ductility, peak bearing capacity, and energy dissipation capacity of the specimens were improved. In addition, with the reduction in seismic damage, the ductility and energy dissipation capacity of the strengthened seismically damaged recycled concrete column specimens were enhanced to different degrees. In particular, the cumulative energy dissipation of the strengthened specimens exposed to medium seismic damage increased most significantly, by 32.5%. In general, the hysteretic curves of the strengthened specimens were full, and the average ductility coefficients were 4.1–6.8. CFRP strengthening was more effective for restoring and enhancing the performance of the recycled concrete column specimens with medium and lower seismic damage levels (displacement ratio ≤ 3%).

HD-Zip, a special class of transcription factors in high plants, has a role in plant development and responding to external environmental stress. Heat stress has always been an important factor affecting plant growth, quality, and yield. Carotenoid content is also an important factor affecting the color of the inner leaf blades of Chinese cabbage. In this study, the genomes of three Brassicaceae plants were selected: Chinese cabbage (Brassica rapa subsp. pekinensis), Brassica oleracea, and Brassica napus. We identified 93, 96, and 184 HD-Zip genes in the B. rapa, B. oleracea, and B. napus, respectively. The HD-Zip gene family was classified into four subfamilies based on phylogeny: I, II, III, and IV;. The results of cis-acting element analysis suggested that HD-Zip family genes may participate in various biological processes, such as pigment synthesis, cell cycle regulation, defense stress response, etc. Conserved motifs prediction revealed that three motifs exist among the four HD-Zip gene families and that different motifs exhibit significant effects on the structural differences in HD-Zips. Synteny, Ks, and 4DTv results displayed that genome-wide triplication events act in HD-Zip gene family expansion. Transcriptome data showed that 18 genes responded (>1.5-fold change) to heat stress in Chinese cabbage, and 14 of 18 genes were from the HD-Zip I subfamily. Three genes had up-regulation, and eight genes had down-regulation in high-carotenoid-content Chinese cabbage. The BraA09g011460.3C expression level was up-regulated after heat stress treatment and significantly reduced in varieties with high carotenoid content, indicating its potential for heat stress tolerance and carotenoid content regulation. This study provided important gene resources for the subsequent breeding of Chinese cabbage.

The grid-connected inverter system may be unstable when connected to a weak grid, and installing an active damper as a virtual resistor at the PCC is convenient for stabilizing the system. This article proposes a passivity enhancement strategy for the grid-connected inverter system via the adaptive active damper. Furthermore, the admittances of the grid-connected inverter system with the active damper are derived, and the real parts of the admittances of the whole system have been calculated. And the admittance measurement results obtained by the frequency scanning method approximately match the theoretical results. Additionally, the virtual resistor’s stability region is discussed, the bandwidth of the phase-locked loop is recommended, ensuring the stabilizing effect of the active damper under the weak grid. And the online resonance frequency detection algorithm guarantees the passivity enhancement of the active damper when grid impedance changes. Finally, controller hardware-in-the-loop tests validate the theoretical analysis of passivity enhancement based on the active damper.

Effective sinusoidal voltage regulation is of permanent importance for grid-forming converters. Usually, the following two types of schemes are employed to achieve a high level of performance: 1) single-loop voltage and 2) dual-loop voltage-current control. The performance of both schemes has comprehensively been evaluated in this work, based on the developed discrete-time model of the LC-filtered grid-forming converter. The challenges of insufficient stability margin, constraint bandwidth, and high sensitivity to parameter variation faced by the single-loop control scheme have been addressed, if the high-performance resonant controllers are employed for voltage regulation. Alternatively, the dual-loop control does not experience such issues with the inclusion of inner-current loop which provides active damping for the overall system. The essence of the inner-current loop is identified based on the discrete root locus analysis. Also, to obtain the highest damping and most enhanced stability, the criterion for current loop design has been addressed and a method for optimal tuning of the inner-current loop is developed, where the original plant with the one-sampling delay and the current gain are considered as the equivalent plant for the voltage controller. Experimental results have verified the effectiveness of the developed method for regulation of grid-forming converters.

The traffic and user have significant impacts on the electric vehicle (EV) charging load but are not considered in the existing research. We propose a novel integrated simulation framework considering the traffic, the user, and power grid as well as the EV traveling, parking and charging based on cellular automaton (CA). The traffic is modeled by the traffic module of the proposed framework based on CA, while the power grid and user are modeled in the EV charging module. The traffic flow, user's charging preference, user's charging satisfaction, and the total supply capability (TSC) in the surveyed region are considered in the proposed framework. Two cases are carried out to show the interactions between the user and power grid. It is shown that the proposed framework can accurately simulate the interactions among traffic situation, user's behavior and TSC, which are significantly lacking in the existing research. The proposed framework is scalable in considering additional interrelated elements.

To suppress the influence of power fluctuation in the DC microgrid system, virtual DC motor (VDM) control is applied to the energy storage converter for improving the stability of the power system. Due to the fixed parameters adopted in the traditional VDM control strategy, the dynamic response of the system cannot be taken into account. Based on the traditional VDM control strategy, a small signal model is established to analyze the influence of the moment of inertia J and the damping coefficient D on the control performance. Moreover, the effects of J and D on the dynamic response of DC bus voltage under power fluctuation are thoroughly analyzed. Consequently, a novel parameter-adaptation-based VDM control strategy is proposed by realizing the adaptive adjustment of J and D. Furthermore, the comparative simulation of three kinds of operating conditions are carried out, and the adaptive parameters are determined through comparative simulation under three kinds of operating conditions. The results show that the proposed control strategy has great superiorities in control effect and flexibility, and the anti-interference and dynamic response abilities of the system are significantly improved, by comparing with the traditional control strategies.

A glucose biosensor was layer-by-layer assembled on a modified glassy carbon electrode (GCE) from a nanocomposite of NAD(P)+-dependent glucose dehydrogenase, aminated polyethylene glycol (mPEG), carboxylic acid-functionalized multi-wall carbon nanotubes (fMWCNTs), and ionic liquid (IL) composite functional polymers. The electrochemical electrode was denoted as NF/IL/GDH/mPEG-fMWCNTs/GCE. The composite polymer membranes were characterized by cyclic voltammetry, ultraviolet-visible spectrophotometry, electrochemical impedance spectroscopy, scanning electron microscopy, and transmission electron microscopy. The cyclic voltammogram of the modified electrode had a pair of well-defined quasi-reversible redox peaks with a formal potential of −61 mV (vs. Ag/AgCl) at a scan rate of 0.05 V s−1. The heterogeneous electron transfer constant (ks) of GDH on the composite functional polymer-modified GCE was 6.5 s−1. The biosensor could sensitively recognize and detect glucose linearly from 0.8 to 100 µM with a detection limit down to 0.46 μM (S/N = 3) and a sensitivity of 29.1 nA μM−1. The apparent Michaelis–Menten constant (Kmapp) of the modified electrode was 0.21 mM. The constructed electrochemical sensor was compared with the high-performance liquid chromatography method for the determination of glucose in commercially available glucose injections. The results demonstrated that the sensor was highly accurate and could be used for the rapid and quantitative determination of glucose concentration.

Non-intrusive Load Monitoring (NILM) is a critical technology that enables detailed analysis of household energy consumption without requiring individual metering of every appliance, and has the capability to provide valuable insights into energy usage behavior, facilitate energy conservation, and optimize load management. Currently, deep learning models have been widely adopted as state-of-the-art approaches for NILM. In this study, we introduce DiffNILM, a novel energy disaggregation framework that utilizes diffusion probabilistic models to distinguish power consumption patterns of individual appliances from aggregated power. Starting from a random Gaussian noise, the target waveform is iteratively reconstructed via a sampler conditioned on the total active power and encoded temporal features. The proposed method is evaluated on two public datasets, REDD and UKDALE. The results demonstrated that DiffNILM outperforms baseline models on several key metrics on both datasets and shows a remarkable ability to effectively recreate complex load signatures. The study highlights the potential of diffusion models to advance the field of NILM and presents a promising approach for future energy disaggregation research.

To solve the problem of the low secret space and security of some image schemes, a novel 4D chaotic system is derived in this paper. Compared with other similar chaotic systems, the new system only has one equilibrium point and can exhibit hyperchaotic characteristics, under some parameter space. The system has better dynamic characters represented by calculation of the Lyapunov exponents, phase planes, and visual 0–1 test diagram. In this study, a novel image encryption algorithm is employed based on the new dynamic system, Zigzag transform, and DNA operation. Based on the improved Zigzag transformation, the plain image is block-scrambled, and DNA encoded with the treated chaotic sequences. The transformation efficiency is improved by combining multiple images at the same time. Numerical analysis has been carried out; the results show that our algorithm achieves much better performance in security, i.e., with enhanced pseudo-randomness, higher key sensitivity, weak correlation, fairly large key space, higher security, and a stronger ability to resist various attacks. Through visual analysis, the algorithm is deemed safe and effective for digital images.

Arsenic and antimony are common toxic metalloids found in associated minerals. These metalloids generally cause high-concentration pollution in non-ferrous metal smelting soils; however, few studies have investigated the pollution characteristics of these two metalloids at non-ferrous smelting sites using varying soil particle sizes. In this study, the valency distributions and geochemical fractions were investigated with varying soil particle sizes (≤ 0.05, 0.05–0.25, 0.25–1, and 1–2 mm). Soils were mainly concentrated in ≤ 0.05 and 0.05–0.25 mm with mass percentages of 32.97% and 29.02%, respectively. The highest total As and Sb concentrations in ≤ 0.05 mm were found to be 20,350 and 3655 mg/kg, respectively. In addition, As(Ⅲ), As(Ⅴ), Sb(Ⅲ), and Sb(Ⅴ) concentrations in this soil particle size were found to be 224, 19,813, 1036, and 24 mg/kg, respectively. The geochemical fractions of As and Sb in varying soil particle sizes were mainly residual, accounting for 50% and 90% in the ≤ 0.05 mm. Soil may bind ≤ 0.25 mm due to the disparity found in the geochemical compositions and valency distributions of arsenic and antimony. X-ray diffraction and scanning electron microscopy/energy dispersive system analysis confirmed that arsenolite accumulated in particle sizes of ≤ 0.05 and 0.05–0.25 mm. The results of this study may provide a scientific reference for risk assessment and restoration strategies for non-ferrous metal smelting soils.

With the extensive use of power electronics converters, harmonic oscillation issues in the multi-paralleled grid-connected inverter system have drawn much attention. Apart from the stability analysis using the impedance-based stability analysis method, the interaction analysis is aimed at revealing the changing process of the system state under the variation of some parameters such as the grid impendence, the number of grid-connected inverters and the control parameter of the inverter current control, etc. In this paper, after comparing the ratio type stability criterion and the sum type stability criterion, the interaction analysis using global admittance is presented in two frequency-domain dimensions. It shows that the harmonic instability depends on both the imaginary part of global admittance which determines the appearance of the resonance point and the real part of global admittance which reflects the property of such resonance point. The essence of this approach is to reveal the appearance of the resonance point and its influence on the system stability. The inherent changing rules of the resonance point are illustrated in the following typical occasions: different grid impendence, different number of grid-connected inverters and different control parameters of the current control loop. Finally, detailed simulations and experimental results validate the effectiveness of the proposed approach.

Conventional single-cell dual buck inverters present high reliability, however they cannot be directly used in high voltage applications, because of the limited voltage rating of commercial switching devices. Therefore, a novel modular multilevel dual buck inverter (MMDBI), capable of processing voltage and power at higher levels, requiring a single dc input voltage, is proposed in this paper. Non-interleaved phase-shifted discontinuous modulation (NIPSDM) and interleaved phase-shifted discontinuous modulation (IPSDM) schemes are applied to the proposed inverter to reduce the current stress in the switching devices. Despite beneficial to the converter efficiency, the use of these discontinuous modulation approaches results in current zero-crossing distortion, which needs to be appropriately managed. In this work, theoretical values for the common-mode and differential-mode current ripples under NIPSDM and IPSDM modulation strategies are derived, and each switching operating mode is fully analyzed. From that, an adjustable current threshold value, which depends on the theoretical current ripple magnitude, is incorporated into the modulation strategy, producing a minimum switching overlap period between the two buck cells that eliminates the current zero-crossing distortion and produces a high-quality output current. Extensive simulation and experimental investigations are presented to demonstrate the feasibility and effectiveness of proposed topology and adjustable discontinuous modulation strategy.

Current control is of utmost importance for grid-connected converters to achieve a high level of performance. The complex proportional integral controller is usually employed for its excellent performance in terms of cross-coupling decoupling and stability. The pole/zero cancellation characteristic of the complex proportional integral controller, which is always valid in the continues-time domain, fails in the discrete-time domain, resulting in an oscillatory or even unstable response. The discrete complex proportional integral controller has thus been addressed in this work, which cancels the complex plant pole with a matching zero provided by the controller in the discrete-time domain. It has been proved that pole/zero cancellation of the discrete complex proportional integral controller is always valid, regardless of the variation of the excitation frequency. An important feature of performance independence from the pulse ratio is thus achieved. Also, to achieve the possible highest performance, a tuning method based on critical damping is developed in the discrete-time domain, which addresses the one-sample delay directly in the tuning process. In this manner, the minimum settling time and negligible overshoot for transient response can be achieved, along with the most enhanced stability and avoidance of closed-loop anomalous peaks. Experimental results have verified the effectiveness of the developed method.

The modular multilevel DC transformer (MMDCT) is more likely to suffer from transient oscillation, which is caused by insufficient damping of the equivalent RLC circuit with smaller arm resistance and submodule capacitance and may threaten the system stability. To tackle this issue, this paper conducts an in-depth analysis of the oscillation generating mechanism and thereby proposes a transient oscillation suppression method by incorporating an oscillation suppression angle (OSA) between the upper and lower arm switching voltages, with which the direction of the circulating current could be adjusted during this overlapped period. However, the open loop control of OSA shows indistinctive improvement of the damping ratio so that a damping compensator for regulating the circulating current is utilized. Furthermore, the compensating gain is optimally designed to achieve the critical damping state based on the small-signal model viewing OSA as an input variable. Besides, the outer capacitor voltage control loop and the power control loop are incorporated to provide the circulating current reference and to track the load power demand, respectively. Extensive simulation results from a realistically designed MMDCT model in PSIM validate the feasibility and effectiveness of the proposed transient oscillation suppression method.

Additive manufacturing has shown giant potential in advanced manufacturing industry. However, distortion of additive-manufactured parts may interrupt the printing process and decrease manufacturing precision, causing a significant waste of time and money. Distortion, a common problem in additive manufacturing, has not been sufficiently researched. In this study, we provide a comprehensive understanding of distortion in additive manufacturing based on assumption of constraining force. A quantitative model was established to illustrate inconsistent shrinkage during the additive process. A qualitative model was then built for showing the distortion caused by inconsistent shrinkage. It can be founded that inconsistent shrinkage accumulated during the additive process drives the final distortion of part. We concluded most influencing factors of distortion together, forming towards a comprehensive understanding of distortion in additive manufacturing. This study not only links micro melting-solidification process and macro structural mechanics in science, but also provides systematic solutions for decreasing the distortion in additive manufacturing for engineering.

The responsibility identification for harmonic oscillation issues, caused by the interaction among the inner control loops of power electronics converters and passive components in renewable energy systems, can provide guidelines to the harmonic oscillation suppression. However, the identification method using the impendence-based stability criterion has not been fully discussed. In this paper, two methods based on a sum type impedance-based stability criterion are proposed to identify the responsibility of each inverter. The proposed Method-1, which is called the result-oriented method, calculates the system state quantitatively assuming one of the inverters is removed from the system and the responsibility of each inverter can be obtained when the calculation is done removing each inverter. The proposed Method-2, which is called the cause-oriented method, employs the calculation of the original system state and the inverter state using the combination weighting method to analyze the responsibility of each inverter on system instability. The former method is more accurate while the later one is more suitable in the large-scale system due to less computation. Finally, simulation and experiment results validate the effectiveness of the proposed methods and analysis.

The existing model predictive control schemes for the matrix converter perform well under ideal input conditions, but are not optimal when source voltages are unbalanced and distorted. The analysis shows that, under input disturbances, the input filter capacitors cause active power fluctuation and further output power quality degradation, which has been ignored in literature. Therefore, a method is proposed to extract the fluctuation with a digital filter and compensate it in the reference generation of source active power, so as to eliminate the output low-frequency harmonics. In the case of input voltage unbalance, a method is proposed to generate the reference source reactive power which could achieve sinusoidal source currents, without the need of separating sequence components. Moreover, effects of source voltage distortions, which degrade the input power quality significantly and are ignored in literature, are suppressed with the proposed generation method of reference reactive power. The extensive experimental results in nine cases have verified the satisfactory steady-state and dynamic performance of the proposed methods.

Background/Aims: Doxorubicin (DOX) is a widely used chemotherapeutic agent for colorectal cancer (CRC). However, the acquirement of DOX resistance limits its clinical application for cancer therapy. Mounting evidence has suggested that aberrantly expressed lncRNAs contribute to drug resistance of various tumors. Our study aimed to explore the role and molecular mechanisms of lncRNA X-inactive specific transcript (XIST) in chemoresistance of CRC to DOX. Methods: The expressions of XIST, miR-124, serum and glucocorticoid-inducible kinase 1 (SGK1) mRNA in DOX-resistant CRC tissues and cells were detected by qRT-PCR or western blot analysis. DOX sensitivity was assessed by detecting IC50 value of DOX, the protein levels of P-glycoprotein (P-gp) and glutathione S-transferase-π (GST-π) and apoptosis. The interactions between XIST, miR-124 and SGK1 were confirmed by luciferase reporter assay, qRT-PCR and western blot. Xenograft tumor assay was used to verify the role of XIST in DOX resistance in CRC in vivo. Results: XIST expression was upregulated and miR-124 expression was downregulated in DOX-resistant CRC tissues and cells. Knockdown of XIST inhibited DOX resistance of CRC cells, as evidenced by the reduced IC50 value of DOX, decreased P-gp and GST-π levels and enhanced apoptosis in XIST-silenced DOX-resistant CRC cells. Additionally, XIST positively regulated SGK1 expression by interacting with miR-124 in DOX-resistant CRC cells. miR-124 suppression strikingly reversed XIST-knockdown-mediated repression on DOX resistance in DOX-resistant CRC cells. Moreover, SGK1-depletion-elicited decrease of DOX resistance was greatly restored by XIST overexpression or miR-124 inhibition in DOX-resistant CRC cells. Furthermore, XIST knockdown enhanced the anti-tumor effect of DOX in CRC in vivo. Conclusion: XIST exerted regulatory function in resistance of DOX possibly through miR-124/SGK1 axis, shedding new light on developing promising therapeutic strategy to overcome chemoresistance in CRC patients.

The performance of optoelectronic devices strongly depends on charge carrier dynamics on top of surfaces of the absorber layers. Unfortunately, this information cannot be selectively probed using conventional ultrafast laser spectroscopic methods, due to the large penetration depth (tens of nm to μm) of the photon pulses in the pump-probe configurations. Therefore, ultrafast time-resolved approaches that can directly and selectively visualize the behavior of the surface carrier dynamics are urgently needed. Here, we introduce a novel methodology of low-voltage scanning ultrafast electron microscopy that can take ultrafast time-resolved images (snapshots) of the surface of materials at the sub-nanometer level. By this approach, the surface of the photoactive materials is optically excited and imaged, using a pulsed low-voltage electron beam (1 keV) that interacts with the surface to generate secondary electrons with an energy of a few eV, and that are emitted only from the top surface of materials, providing direct information about the carrier dynamics and the localization of electron/holes in real space and time. An outlook on the potential applications of this low voltage approach in different disciplines will also be discussed.

Background/Aims: Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) is an ideal anti-tumor drug because it exhibits selective cytotoxicity against cancer cells. However, certain cancer cells are resistant to TRAIL, and the potential mechanisms are still unclear. The aim of this study was to reduce the resistance of colorectal cancer (CRC) cells to TRAIL. Methods: Quantitative real-time PCR analysis was performed to detect the expression of microRNA-128 (miR-128) in tissues from patients with CRC and CRC cell lines. MTT assays were used to evaluate the effect of miR-128 on TRAIL-induced cytotoxicity against CRC cell lines. The distribution of death receptor 5 (DR5) and the production of reactive oxygen species (ROS) were detected by flow cytometry analysis. Western blot, flow cytometry, and luciferase reporter assays were performed to evaluate the potential mechanism and pathway of miR-128-promoted apoptosis in TRAIL-treated CRC cells. Results: MiR-128 expression was downregulated in tumor tissues from patients with CRC as well as in CRC cell lines in vitro. The enforced expression of miR-128 sensitized CRC cells to TRAIL-induced cytotoxicity by inducing apoptosis. Mechanistically, bioinformatics, western blot analysis, and luciferase reporter assays showed that miR-128 directly targeted sirtuin 1 (SIRT1) in CRC cells. miR-128 overexpression suppressed SIRT1 expression, which promoted the production of ROS in TRAIL-treated CRC cells. This increase of ROS subsequently induced DR5 expression, and thus increased TRAIL-induced apoptosis in CRC cells. Conclusion: The combination of miR-128 with TRAIL may represent a novel approach for the treatment of CRC.

High-frequency switching circulating currents are inevitable in multi-module parallel connected converters, which will result in increased power losses and declined system stability, reliability and control precision. In view of this, the formation mechanism of the switching circulating currents is first researched at both power switch level and circuit level in this paper. Next, the switching circulating currents in an N-module converter based on the sinusoidal pulse width modulation (SPWM) technique are mathematically modeled. On this basis, their distribution characteristics in terms of carrier phase deviation are analyzed in detail. In particular, a typical case considering the carrier phase shifting SPWM technique is utilized to further explore the circulating current distribution features. Then, three typical voltage and current closed-loop control approaches considering LCand LCL-type filters are studied, for the purpose of developing an optimum solution for the circulating current inhibition. The theoretical analysis and experimental results validate the effectiveness of the proposed analysis means and the restraining strategy of the high-frequency switching circulating currents.

This paper presents an input-series-output-series modular multilevel dc transformer (ISOS-M2DCT) with an inter-module arithmetic phase interleaving control (IAPIC) for high-voltage dc transmission and medium-voltage dc distribution application. The presented ISOS-M2DCT has several advantages over conventional dual active bridge (DAB)-based dc transformer (DAB-DCT) and M2DCTs. It possesses a higher power capacity, a dc fault tolerant superiority, and a higher power factor in heavy load than DAB-DCT; it simplifies the manufacturing of ac link transformers and averts the problem of circulating currents among different modules compared with M2DCTs. The introduced IAPIC is able to cut down the dc ripples without any rise in volume of passive elements, thereby making it easier to realize the compact design of ISOS-M2DCT. In this paper, the topology, operation principle, modulation strategy, basic control scheme, power characterization, the generating mechanism of dc ripples, and the IAPIC scheme are proposed and analyzed successively. Finally, an ISOS-M2DCT prototype is built, and the proposed method is verified by simulation and experimental results.