Active Switches Research Articles

Multi-Period Optimal Transmission Switching with Voltage Stability and Security Constraints by the Minimum Number of Actions

Due to the ever-growing load demand and the deregulation of the electricity market, power systems often run near the stability boundaries, which deteriorates system voltage stability and raises voltage issues for the stable operations of power systems. Transmission switching (TS) has been applied to improve economic benefits and security operations for many applications. In this paper, a multi-period voltage stability-constrained problem (MP-VSTS) is established, intending to improve voltage security and the stability of a power system. Considering the online application of transmission switching, the minimum number of switching actions is taken as the objective function of the proposed MP-VSTS problem, which extends the TS application for real industries. The proposed model provides the switching lines for the upcoming period and the state of power systems for several successive periods. To overcome the solving difficulties of the proposed model, a two-stage approach is presented, which balances speed and accuracy. Numerical studies on the IEEE 118- and 662-bus power systems have demonstrated the proposed approach’s performance.

IF1 is a cold-regulated switch of ATP synthase hydrolytic activity to support thermogenesis in brown fat

While mechanisms controlling uncoupling protein-1 (UCP1) in thermogenic adipocytes play a pivotal role in non-shivering thermogenesis, it remains unclear whether F1Fo-ATP synthase function is also regulated in brown adipose tissue (BAT). Here, we show that inhibitory factor 1 (IF1, encoded by Atp5if1), an inhibitor of ATP synthase hydrolytic activity, is a critical negative regulator of brown adipocyte energy metabolism. In vivo, IF1 levels are diminished in BAT of cold-adapted mice compared to controls. Additionally, the capacity of ATP synthase to generate mitochondrial membrane potential (MMP) through ATP hydrolysis (the so-called “reverse mode” of ATP synthase) is increased in brown fat. In cultured brown adipocytes, IF1 overexpression results in an inability of mitochondria to sustain the MMP upon adrenergic stimulation, leading to a quiescent-like phenotype in brown adipocytes. In mice, adeno-associated virus-mediated IF1 overexpression in BAT suppresses adrenergic-stimulated thermogenesis and decreases mitochondrial respiration in BAT. Taken together, our work identifies downregulation of IF1 upon cold as a critical event for the facilitation of the reverse mode of ATP synthase as well as to enable energetic adaptation of BAT to effectively support non-shivering thermogenesis.

Synthesis of a 13C/2H Labeled Building Block to Probe the Phosphotyrosine Interactome Using Biomolecular NMR Spectroscopy.

Phosphotyrosine (pTyr) recognition coordinates the assembly of protein complexes, thus controlling key events of cell cycle, cell development and programmed cell death. Although many aspects of membrane receptor function and intracellular signal transduction have been deciphered in the last decades, the details of how phosphorylation alters protein-protein interaction and creates regulating switches of protein activity and localization often remains unclear. We developed a synthetic route to a protected phophotyrosine building block with isolated 13C-1H spins in the aromatic ring. The compound can be used for solid phase peptide synthesis (SPPS) and readily applied to study affinity, dynamics and interactions on an atomic level using NMR spectroscopy. As a first example, we prepared an isotopologue of a pTyr containing 12mer peptide (pY1021) as part of the platelet-derived growth factor to analyze the binding to the phospholipase C-γ (PLCγ-1) SH2 domain.

Dual-Band Matching Networks Using a Combination of Microstrip Lines and Active Switching Components

Active switching components are employed to propose a novel compact dual-band matching network (MN) with an adapted frequency in this paper. The design method involves the integration of active switching devices, stepped impedance resonator (SIR), and microstrip transmission line into the frequency response of a dual-band MNs. The PIN diode is employed as an active switching device in the proposed structure to increase the bandwidth of the MNs and attain the desired frequency. The dual-band MNs that are being proposed are fabricated and designed on the Rogers RO4350B substrate for use in Wireless Local Area Networks (WLANs). The simulation results demonstrate a high degree of congruence with the measurements. The maximal insertion losses and return losses in the first band are -1.3 and -24 dB, respectively. In the second band, they are -2.2 and -20.69 dB. The primary benefits of the proposed dual-band MNs are their high attenuation between two passbands, frequency matching capability, suitable return loss, and low insertion loss.

A Family of Single-Phase Buck-Boost AC-AC Converters Based on Impedance Network Cells With Reduced Active Switches

A Family of Single-Phase Buck-Boost AC-AC Converters Based on Impedance Network Cells With Reduced Active Switches

Non-Intrusive Load Monitoring Based on Dimensionality Reduction and Adapted Spatial Clustering

Non-invasive load monitoring (NILM) deduces changes in energy consumption patterns and operational statuses of electrical equipment from power signals in the feed line. With the emergence of fine-grained power load distribution, the importance of utilizing this technology for implementing demand-side energy management in smart grid development has become increasingly prominent. To address the issue of low load identification accuracy stemming from complex and diverse load types, this paper introduces a NILM method based on uniform manifold approximation and projection (UMAP) reduction and enhanced density-based spatial clustering of applications with noise (DBSCAN). Firstly, this paper combines the characteristics of user load under transient and steady-state conditions and selects data with significant differences to construct a load-characteristic database. Additionally, UMAP is employed to reduce the dimensionality of high-dimensional load features and rebuild a load feature database. Subsequently, DBSCAN is utilized to categorize typical user loads, followed by a correlation analysis with the load-characteristic database to determine the types or classes of loads that involve switching actions. Finally, this paper simulates and analyzes the proposed method using the electricity consumption data of industrial users from the CER–Electricity–Data dataset. It identifies the electricity load data commonly utilized by users in a specific area of Zhejiang Province in China. The experimental results indicate that the accuracy of the proposed non-invasive load identification method reaches 95%. Compared to the wavelet transform, decision tree, and backpropagation network methods, the improvement is approximately 5%.

Electrically switchable metamaterial analogue to electromagnetically induced transparency

In this paper, we propose an active electromagnetically induced transparency-like (EIT-like) metamaterial to investigate the electrically switchable behaviors. The EIT-like metamaterial is constructed by a “bright” comb-line resonator side-coupled with a “dark” split-ring resonator. The “bright” and “dark” resonators are individually or simultaneously soldered with PIN diodes. The diodes are connected with DC voltage sources through conducting wires. By adjusting the bias voltage within the range of 0.0–1.2 V, the resistance of PIN diode can be changed from 9000 to 1 Ω, thereby dynamically modulating the EIT-like spectrum. Both simulation and experiment results indicate that this active configuration can generate remarkable multi-band amplitude modulations on the EIT-like spectrum, and a significant modulation depth of up to 18.3 dB was achieved on the tested transmission through the metamaterial. Moreover, the transformation of transparency-to-absorption and slow light on-to-off switching actions are also obtained via electric biasing the proposed sample. These findings resulted from the EIT-like mechanism, which may promote the development of actively controlled photonic devices.

Reversible Switch of Artificial Selenoenzyme Activity Modulated by Metal Ion-Induced Protein Nano-Assemblies

Reversible Switch of Artificial Selenoenzyme Activity Modulated by Metal Ion-Induced Protein Nano-Assemblies

State Space Average Modeling, Small Signal Analysis, and Control Implementation of an Efficient Single-Switch High-Gain Multicell Boost DC-DC Converter with Low Voltage Stress

This paper presents the closed-loop control of a single-switch high-gain multicell boost DC-DC converter working in a continuous conduction mode (CCM). This converter is particularly designed for applications in photovoltaic systems. One of the main advantages of the proposed converter is that it only employs one active semiconductor switch, which decreases the converter losses and cost, increases the efficiency, and simplifies the control circuit. Moreover, the multicell nature of the proposed converter offers the possibility of obtaining the required voltage gain by selecting the number of cells. State space average (SSA) modeling and small-signal analysis are used to model the switching converter power stages of the proposed converter. The parasitic series resistances of the passive elements of the converter circuit are considered to improve the accuracy of the modeling. Small-signal analysis is used to derive the open-loop transfer functions, input-to-output and control-to-output transfer functions of the proposed converter to examine its dynamic performance. The stability of the converter is analyzed to design the parameters of the voltage controller using the proposed modeling method. The experimental prototype of the proposed single-switch two-cell boost DC-DC converter was implemented. The simulation and experimental results proved the effectiveness of the proposed boost DC-DC converter under different working conditions. It has a fast dynamic response without overshoots. A comprehensive comparison between the proposed converter and previous boost converters is provided. It guarantees a required variable and constant high voltage gain with a wider duty ratio range. It compromises between the required performance, the low number of components, low voltage stress on the components, and cost-effectiveness. The experimental efficiency of the proposed converter is about 96% at a 100 W load.

B-Cell Epigenetic Modulation of IgA Response by 5-Azacytidine and IgA Nephropathy.

IgA nephropathy is an important global cause of kidney failure. Dysregulation of IgA production is thought to play a key role in IgA nephropathy pathogenesis, however, little is known about the epigenetic mechanisms such as RNA 5- methylcytosine (5mC) modification in regulating IgA synthesis. To decipher the role of RNA 5mC in regulation of IgA class switch, the miR-23b-/- and LCWE induced Kawasaki disease mice were treated with 5-azacytidine. Trdmt1-/- and double Trdmt1-/-/ miR-23b-/- mice, Aid-/- mice or Aid-/-/ miR-23b-/- mice were also employed. We showed that miR-23b down regulated expression of Transfer RNA Aspartic Acid Methyltransferase 1 (Trdmt1) and consequently reduced 5-methylcytosine (m5C) RNA modification and IgA synthesis in B cells. Inhibition of m5C RNA modification normalised serum IgA levels and ameliorated progression of the IgA nephropathy-like kidney disease in miR-23b-/- and Kawasaki disease mice while mesangial IgA and C3 deposition failed to develop in Trdmt1-/-miR-23b-/- mice. By contrast, increased m5C RNA modification resulted in an exaggerated IgA nephropathy phenotype. miR-23b regulation of serum IgA levels and the development of an IgA nephropathy-like kidney disease in miR-23b-/- and Kawasaki disease mice is likely mediated through TRDMT1 driven 5-methylcytosine RNA modification in B cells, resulting in impaired activation-induced cytidine deaminase activity and IgA class switch recombination. This study revealed TRDMT1 induced RNA 5mC methylation regulate IgA class switch and inhibition of RNA 5mC by 5-Azacytidine could ameliorate progression of IgA nephropathy.

Modeling mobile shales under contraction: Critical analyses of new analog simulations of shale tectonics and comparison with salt-bearing systems

Weak substrates, such as salt and mobile shales, exert a strong control on deformation styles in all structural settings, especially those undergoing contraction. Despite both materials being very weak, they are mechanically very different. Salt is weak and will flow in a ductile fashion under most geologic conditions, whereas shales only become mobile after reaching a critical state. Many sandbox-style physical or analog modeling studies have typically used a salt analog, viscous silicone polymer, as a proxy for mobile shales. However, to more accurately model mobile shale behavior, the model material needs to exhibit yield strength. One such material is Carbopol, which is made up of microgel grains that are elasto-plastic, separated by a viscous interstitial fluid. The abundance of the grains depends on the concentration of the mixture. Our results show that Carbopol does behave much differently than the traditional salt analog during contraction. Polydimethylsiloxanes typically undergoes bulk deformation and inflation under contraction, whereas Carbopol forms discrete, intense shear zones and contains zones of little to no strain where its yield strength has not been exceeded. Below the shale analog, brittle layers typically form imbricate thrust stacks, jacking up the overburden, with shear zones propagating out from thrust tips along and through the shale proxy. Strain analyses reveal complex switching of activity within the Carbopol and overlying sediments. Models reveal that even a very thin layer of Carbopol can act as a highly efficient detachment, and form more geologically realistic shortening structures, especially where these detachments are vertically stacked and horizontally offset. We believe that Carbopol is a powerful mobile-shale analog and opens new modeling directions because, as far as we are aware, this material has never been incorporated into a traditional sandbox model. Future work will seek to incorporate this material into more complex and 3D sandbox-style models.

Dynamic Line Rating for Congestion Management in Distribution Network

The growth of the demand because of the electrification of the heating system and the popularization of the use of electric vehicles added to an increase on the renewable energies generation connected to the distribution level, are responsible for an increase in the use of distribution network. This may lead to more congestions at this level that up to the date, are solved with direct switching actions which implies a negative economic impact and consequences for consumers and producers. Congestions can be solved also with market-based demand response which need the system to have flexibility to be applied effectively. On transmission network the usage of dynamic line rating (DLR) is more extended but on the distribution level, it is not common. This paper aims to show the use of DLR to provide flexibility to the distribution network, easing congestion management.

Model predictive control for single-phase cascaded H-bridge photovoltaic inverter system considering common-mode voltage suppression

In this article, a model predictive control (MPC) with common-mode voltage (CMV) suppression is proposed for single-phase cascaded H-bridge (CHB) inverters, which can also simultaneously achieve control objectives of grid-connected current tracking, voltages balancing of different H-bridge submodules on the DC-side and switching frequency reduction. To suppress high-frequency components of the common-mode voltage without additional switching devices, the algorithm proposed designs the predicted and reference values of the CMV and incorporates them in the cost function. At the same time, the capacitor voltages balancing control is integrated in the calculation of the optimal modulation function of the H-bridge, which reduces the complexity of control effectively. Besides, switching times of the MOSFETs are compared in two cycles. The cost function is constructed to represent comprehensive effect of the control. Finally, an experiment is performed on the hardware-in-the-loop experimental platform. The experimental results show that the proposed algorithm can offer a better voltage THD and reduce the times of switch action by nearly half while maintaining high-precision current tracking and maximum power point of photovoltaic modules, which alleviate the potential electromagnetic interference and cabling problem.

Bevacizumab Erlotinib Switch Maintenance in Chemo-Responsive Advanced Gallbladder and Cholangiocarcinoma (BEER BTC): A Multicenter, Open-Label, Randomized, Phase II Trial.

Patients with chemotherapy-responsive advanced biliary tract cancers (BTCs) are usually observed after 6 months of gemcitabine-based therapy. There is limited prospective evidence for maintenance strategies after chemotherapy. This investigator-initiated, open-label, randomized, integrated phase II-III study enrolled adult patients with advanced BTC from two cancer centers in India. Patients with histologically confirmed advanced biliary tract adenocarcinoma who had at least disease stabilization after 6 months of gemcitabine-based chemotherapy were randomly assigned (1:1) to either active surveillance or switch maintenance, which was a combination of bevacizumab 5 mg/kg intravenous once every 21 days plus erlotinib 100 mg once daily. Both arms were continued until disease progression, unacceptable toxicity, or patient decision to withdraw. The primary end point of the phase II component of the trial was investigator-evaluated progression-free survival. This trial is registered with Clinical Trials Registry of India (CTRI/2019/05/019323I). From May 2021 to November 2022, 98 patients were randomly assigned to active surveillance (n = 49) or bevacizumab-erlotinib (n = 49). A majority of patients had gallbladder cancer (80%). The median follow-up was 13.4 months. The median progression-free survival was 3.1 months (95% CI, 2.47 to 3.64) in the active surveillance group versus 5.3 months (95% CI, 3.53 to 7.04) in the bevacizumab-erlotinib group (hazard ratio, 0.51 [95% CI, 0.33 to 0·74]; P = .0013). The most common grade 3 class-specific adverse events associated with bevacizumab-erlotinib were acneiform rash 1 (2%) and oral stomatitis 1 (2%) with erlotinib and bleeding 1 (2%) with bevacizumab. The combination of bevacizumab and erlotinib as switch maintenance improves progression-free survival with an acceptable safety profile compared with active surveillance in patients with advanced BTCs in this phase II study. The trial moves on to the phase III component to evaluate improvement in overall survival.

Unlocking responsive flexibility within local energy communities in the presence of grid-scale batteries

The transition towards a decentralized, decarbonized, and distributed energy infrastructure necessitates techno-economic initiatives to empower local energy communities (LECs) to achieve self-reliance and evolve into self-sustained electricity networks. It is crucial to underscore the significance of network resilience, especially in the context of local power generation, battery storage, and the radial topology of low-voltage (LV) networks. While contemporary LV networks have made significant attempts to integrate distributed energy resources (DERs), the notable deficiency lies in their lack of network redundancy, posing a substantial challenge in the occurrence of high-impact, low-probability (HILP) events. Therefore, to enhance LV network resilience and leverage its capability to withstand unexpected disruptions, the network operator needs to unlock the potential contributions of end-users within the active distribution networks (ADNs). In this paper, a comprehensive model is developed based on multi-temporal optimal power flow (MTOPF) for unbalanced LV networks addressing the technical issues in islanded microgrid operational planning. The contributions of the grid-scale batteries in forming islanded microgrids and the flexibility that can be provided by the end-users in the LEC have been considered in this paper. To demonstrate the performance of the proposed model, the simulation studies have been carried out on a part of medium and low voltage networks, consisting of network reconfiguration and load transferring capability to reduce the service interruptions during HILP events. The energy-not-served (ENS) is chosen as one of the key performance indicators (KPIs) in this study. With the unlocking flexibility potentials and contribution of the DERs, including grid-scale energy storage (GES) units and Photovoltaic (PV) panels, the ENS has been reduced from 700.8 kWh to 447.5 kWh by activating the local resources, proper switching action, and contribution of the flexible loads, for one of the severe HILP events, i.e., the main grid outage. In this case, the full load curtailment index is reduced from 180 to 106 client hours.

Unveiling the molecular mechanisms of the type IX secretion system's response regulator: Structural and functional insights.

The type IX secretion system (T9SS) is a nanomachinery utilized by bacterial pathogens to facilitate infection. The system is regulated by a signaling cascade serving as its activation switch. A pivotal member in this cascade, the response regulator protein PorX, represents a promising drug target to prevent the secretion of virulence factors. Here, we provide a comprehensive characterization of PorX both in vitro and in vivo. First, our structural studies revealed PorX harbors a unique enzymatic effector domain, which, surprisingly, shares structural similarities with the alkaline phosphatase superfamily, involved in nucleotide and lipid signaling pathways. Importantly, such pathways have not been associated with the T9SS until now. Enzymatic characterization of PorX's effector domain revealed a zinc-dependent phosphodiesterase activity, with active site dimensions suitable to accommodate a large substrate. Unlike typical response regulators that dimerize via their receiver domain upon phosphorylation, we found that zinc can also induce conformational changes and promote PorX's dimerization via an unexpected interface. These findings suggest that PorX can serve as a cellular zinc sensor, broadening our understanding of its regulatory mechanisms. Despite the strict conservation of PorX in T9SS-utilizing bacteria, we demonstrate that PorX is essential for virulence factors secretion in Porphyromonas gingivalis and affects metabolic enzymes secretion in the nonpathogenic Flavobacterium johnsoniae, but not for the secretion of gliding adhesins. Overall, this study advances our structural and functional understanding of PorX, highlighting its potential as a druggable target for intervention strategies aimed at disrupting the T9SS and mitigating virulence in pathogenic species.

Load restoration of electricity distribution systems using a novel two‐stage method

AbstractThis paper proposes a new comprehensive load restoration (LR) method for electrical distribution networks. Since two main technologies of switching equipment are there in the modern distribution networks, namely manual switches (MSs) and remote‐controlled switches (RCSs), this article has benefited from this concept effectively. A two‐stage algorithm that provides the system operators with the ability to recover part of the loads in the shortest possible time by RCSs is proposed. After this step, the remaining loads will be restored by a combination of MSs and RCSs. The other strength of this algorithm is to provide accurate and practical solutions so that the sequence of switching actions is clearly defined. Also, using an innovative index called expected weighted energy not supplied as the objective function of the main problem will ensure the operators recover the maximum amount of load in the shortest time possible. This novel method was applied on a sample standard IEEE distribution test network. The simulation results proved the effectiveness of this proposed method.

Parallel/Series Connected Standardized Active Switching Modules for High Power DCCBs in MVDC Networks

Parallel/Series Connected Standardized Active Switching Modules for High Power DCCBs in MVDC Networks

Interleaved Modified SEPIC Converters with Soft Switching and High Power Factor for LED Lighting Appliance

A novel ac/dc LED driver with power factor correction and soft-switching functions is proposed. The circuit topology mainly consists of two modified single-ended primary inductance converters (SEPIC) with interleaved operation. The first half stage of SEPIC operates like a boost converter and the second half stage operates like a buck–boost converter. Each boost converter is designed to operate in discontinuous current mode (DCM) to function as a power factor corrector (PFC). The two buck–boost converters that share a commonly coupled inductor are designed to operate at near boundary conduction mode (BCM). Without using any active clamping circuit, auxiliary switch or snubber circuit, the active switches can achieve zero-voltage switching on, and all diodes achieve zero-current switching off. First, operation modes in steady state are analyzed, and the mathematical equations for design component parameters are derived. Finally, a prototype circuit of 180 W rated power was built and tested. Experimental results show satisfactory performance of the proposed circuit.

Secretory Nogo-B regulates Th2 differentiation in the lung cancer microenvironment

Nogo-B, a ubiquitously expressed member of the reticulon family, plays an important role in maintaining endoplasmic reticulum (ER) structure, regulating protein folding, and calcium homeostasis. In this study, we demonstrate that Nogo-B expression and secretion are upregulated in lung cancer and correlate to overall survival. Nogo-B is secreted by various cells, particularly lung cancer cells. ER stress and phosphorylation at serine 107 can induce Nogo-B secretion. Secretory Nogo-B suppresses the differentiation of Th2 cells and the release of type 2 cytokines, thus influencing the anti-tumor effects of Th2-related immune cells, including IgE+B cell class switching and eosinophil activation.