Search Results (624)

The higher integration of photovoltaic (PV) units is an inevitable component of smart city development. Thanks to smart meter devices that can record the exchange of power between the grid and customers, it is expected that homeowners and businesses will tend to install PV arrays on their rooftops and parking lots to benefit from selling power back to the grid. However, the overvoltage issue resulting from high PV penetration is a major challenge that necessitates the active power curtailment of PV units to ensure power grid stability. Fairness-oriented methods aim to minimize the active power of PV units as much as possible, adopting a fairer approach, and then address the PV owner’s satisfaction with fair profit and loss. Maintaining voltage within a limited standard range under very low load conditions while prioritizing PV inverters’ participation in reactive power contribution and attempting to ensure fairer curtailment of active power presents challenges to existing control design approaches. This paper presents twelve new volt–watt curve design methods to achieve these goals and address the challenges. The methods yield polynomial curves, piecewise linear curves, and single linear curves. A unique voltage sensitivity value for each PV inverter is used to determine the control region area and the slope of the curve at the starting point in certain instances. The effectiveness of the proposed methods is discussed by evaluating their capabilities on the 37-bus IEEE system. Full article

Coronary CT angiography (CCTA) has seen steady progress since its inception, becoming a key player in the non-invasive assessment of coronary artery disease (CAD). Advancements in CT technology, including iterative and deep-learning-based reconstruction, wide-area detectors, and dual-source systems, have helped mitigate early limitations, such as high radiation doses, motion artifacts, high iodine load, and non-diagnostic image quality. However, the adjustments between ionizing radiation and iodinated contrast material (CM) volumes remain a critical concern, especially due to the increasing use of CCTA in various indications. This review explores the balance between radiation and CM volumes, emphasizing patient-specific protocol optimization to improve diagnostic accuracy while minimizing risks. Radiation dose reduction strategies, such as low tube voltage protocols, prospective ECG-gating, and modern reconstruction algorithms, have significantly decreased radiation exposure, with some studies achieving sub-millisievert doses. Similarly, CM volume optimization, including adjustments in strategies for calculating CM volume, iodine concentration, and flow protocols, plays a role in managing risks such as contrast-associated acute kidney injury, particularly in patients with renal impairment. Emerging technologies, such as photon-counting CT and deep-learning reconstruction, promise further improvements in dose efficiency and image quality. This review summarizes current evidence, highlights the benefits and limitations of dose control approaches, and provides practical recommendations for practitioners. By tailoring protocols to patient characteristics, such as age, renal function, and body habitus, clinicians can achieve an optimal trade-off between diagnostic accuracy and patient safety, ensuring optimal operation of CT systems in clinical practice. Full article

A triboelectric nanogenerator (TENG) holds significant potential as a self-powered pressure sensor due to its ability to convert mechanical energy into electrical energy. The output voltage of a TENG is directly correlated with the applied pressure, making it highly suitable for pressure sensing applications. Among the key factors influencing TENG performance, the microstructure on the surface plays a crucial role. However, the effect of surface microstructure on charge transfer behavior remains relatively underexplored. Here, a stripe-patterned rough TENG (SR-TENG) fabricated by laser ablation and molding is proposed. The stripe-patterned rough surface exhibits excellent deformation properties, allowing for more effective contact area between the tribolayers. Additionally, the localized surface-edge enhanced electric field at the stripe boundaries improves surface charge transfer, thereby enhancing overall output performance. The SR-TENG achieved an open-circuit voltage of 97 V, a short-circuit current of 59.6 μA, an instantaneous power of 3.55 mW, and a power density of 1.54 W/m². As an energy harvester, the SR-TENG successfully powered 150 LEDs. A linear relationship between applied pressure and output voltage was established with a coefficient of determination R² = 0.94, demonstrating a high sensitivity of 14.14 V/kPa. For practical application, a novel self-powered two-digit pressure switch was developed based on the SR-TENG. This system enables the control of two different LEDs using a single TENG device, triggered by applying a light or hard press. Full article

This paper presents a fully integrated bandpass filter (BPF) with high tunability based on a novel differential active inductor (DAI), designed for sensor interface circuits operating in the ultra-high frequency (UHF) band. The design of the proposed DAI is based on a symmetrical configuration, utilizing a differential amplifier for the feedforward transconductance and a common-source (CS) transistor for the feedback transconductance. By integrating a cascode scheme with a feedback resistor, the quality factor of the active inductor is significantly improved, leading to enhanced mid-band gain for the bandpass filter. To facilitate independent tuning of the BPF‘s center frequency and mid-band gain, an active resistor adjustment and bias voltage control are employed, providing precise control over the filter’s operational parameters. Post-layout simulations and process corner results are conducted with 0.13 µm CMOS technology at 1.2 V supply voltage. The proposed second order BPF achieves a broad tuning range of 280 MHz to 2.426 GHz, with a passband gain between 8.9 dB and 16.54 dB. The design demonstrates a maximum noise figure of 16.54 dB at 280 MHz, an input-referred 1 dB compression point of −3.78 dBm, and a third-order input intercept point (IIP3) of −0.897 dBm. Additionally, the BPF occupies an active area of only 68.2×30 µm², including impedance-matching part, and consumes a DC power of 14–20 mW. The compact size and low power consumption of the design make it highly suitable for integration into modern wireless sensor interfaces where performance and area efficiency are critical. Full article

By using a soft normal open point (SNOP) to connect multiple distribution networks to form a flexible interconnected distribution system (FIDS), the power distribution can be flexibly and controllably regulated among distribution stations, but it is also necessary to ensure the system’s operational efficiency and maintain voltage quality when carrying out optimal scheduling. In this paper, a FIDS optimal scheduling strategy considering dynamic weight grading is proposed. By considering the voltage overrun status of each distribution station area, the voltage level of each distribution station area is divided into three voltage overrun situations, including normal operation, safe boundary, and protection boundary levels, and an optimal scheduling model applicable to the multi-level operation of the FIDS is constructed. In order to adapt to the coordinated optimal operation objectives under different overrun levels, an optimal operation strategy considering the dynamic weights of system operation cost, voltage deviation, customer satisfaction, and SNOP regulation capability is proposed and finally simulated and verified using the improved IEEE33 node arithmetic case. The results verify the effectiveness of the method proposed in this paper in improving the system’s operational efficiency and node voltage quality. Full article

Prolonged healing time of acute burn wounds is associated with increased pain, infection, risk of scarring, poorer mobility and higher financial and emotional burden. Electrical stimulation (ES) reduces healing time in chronic wounds; however, its reported use on acute burn wounds is limited. This systematic review (SR) aimed to evaluate the relative benefit of ES compared to routine wound care on the healing time of acute burn wounds in adults. The online databases queried included Cochrane Database of SR’s, MEDLINE, EMBASE, PUBMED and CINAHL. The search criteria included RCTs involving the application of ES of varying voltage, duration and modality in acute burn patients aged ≥18 years. The primary outcome investigated was days to burn wound closure, while the secondary outcomes included edema and infection. Four RCTs were discovered, involving a total of 143 participants with a mean age 35.5 years. Two RCTs demonstrated (a) 36% (2.6 days) reduction in time to wound closure with ES (p < 0.001); and (b) significant reduction in wound area with ES (11.2 ± 3.2 cm², p < 0.001) compared to controls at 21 days. Two RCTs found ES promoted better wound-healing environments, reducing edema, bacterial infection, and biofilm. This review highlighted low-risk wound-healing benefits with ES as a feasible adjunct to routine burn care. Full article

The potential for electricity distribution in power systems has significantly increased over the years. This is mainly because of the discovery of alternative electricity generation sources, such as renewable energy, coupled with distributed generation (DG), making electricity more widely accessible. However, challenges remain in distributing electricity to remote area communities (RACs), especially because of difficult terrain and the complexity of installing power plants, leaving some areas without access to electricity. In this study, we used an improved particle swarm optimization (IPSO) technique to propose multi-objective energy management for remote area communities within a hybrid integrated Photovoltaic–(PV)–Hydropower plant (HPP)–Battery Energy Storage System (BESS). The multi-objective functions enhance power quality and voltage stability to meet grid code requirements. The proposed method was applied to the IEEE 15-bus system, which is consistent with systems commonly used in remote area communities, under the following scenarios: Case I—random installation of PV-HPP-BESS and PI parameter control of BESS; Case II—optimal location of PV-HP-BESS and PI parameter control of BESS using IPSO; Case III—sudden short circuit of the transmission line in Case II. Effectiveness was verified through hardware-in-the-loop (HIL) testing. The experimental results indicate that the proposed method significantly improves power quality and stability under disturbances, demonstrating superior performance. Full article

We report an ion-gel-gated amorphous indium gallium zinc oxide (a-IGZO) optoelectronic neuromorphic transistors capable of synaptic emulation in both photoelectric dual modes. The ion-gel dielectric in the coplanar-structured transistor, fabricated via ink-jet printing, exhibits excellent double-layer capacitance (>1 μF/cm²) and supports low-voltage operation through lateral gate coupling. The integration of ink-jet printing technology enables scalable and large-area fabrication, highlighting its industrial feasibility. Electrical stimulation-induced artificial synaptic behaviors were successfully demonstrated through ion migration in the gel matrix. Through a simple and controllable oxygen vacancy engineering process involving low-temperature oxygen-free growth and post-annealing process, a sufficient density of stable subgap states was generated in IGZO, extending its responsivity spectrum to the visible-red region and enabling wavelength-discriminative photoresponses to 450/532/638 nm visible light. Notably, the subgap states exhibited unique interaction dynamics with low-energy photons in optically triggered pulse responses. Critical synaptic functionalities—including short-term plasticity (STP), long-term plasticity (LTP), and paired-pulse facilitation (PPF)—were successfully simulated under both optical and electrical stimulations. The device achieves low energy consumption while maintaining compatibility with flexible substrates through low-temperature processing (≤150 °C). This study establishes a scalable platform for multimodal neuromorphic systems utilizing printed iontronic architectures. Full article

To ensure the reliability and security of Colombia’s national power system, there is an ongoing necessity for upgrades in monitoring and protection mechanisms. Approximately sixteen years ago, the introduction of synchrophasor measurements enabled the swift detection of potentially network-detrimental events. Subsequent advancements have seen the deployment of Phasor Measurement Units (PMUs), currently tallying 150 across 25 substations, facilitating real-time monitoring and analysis. The growth of the PMU network is pivotal for the modernization of the National Control Center, particularly in the face of complexities introduced by renewable energy sources. There is an increasing demand for data analytics platforms to support operators in responding to threats. This paper explores the development of the Colombian Wide-Area Measurement System (WAMS) network, highlighting its milestones and advancements. Significant contributions include the technological evolution of the WAMS for real-time monitoring, an innovative high-speed data analytics strategy, and tools for the monitoring of frequency, rate of change of frequency (RoCoF), angular differences, oscillations, and voltage recovery, alongside industry-specific criteria for real-time assessment. Implemented within an operational WAMS, these tools enhance situational awareness, thereby assisting operators in decision-making and augmenting the power system’s reliability, security, and efficiency, underscoring their significance in modernization and sustainability initiatives. Full article

Grouting technology is widely used in construction and civil engineering, where evaluating grouting effectiveness is crucial due to the uncertainty of subsurface conditions. Existing methods face drawbacks such as destructiveness, high cost, poor durability, and limited data collection. To address these issues, this paper proposes a novel wireless real-time monitoring system based on a ZigBee sensor network framework. The sensor system integrates a direct current method in geophysics with apparent resistivity measurement to assess grouting effectiveness in real time. It consists of multichannel data acquisition units with electrodes for sensing underground currents and a user control unit for centralized management and data processing. A system acquisition performance test confirmed that the differential input channel’s equivalent input noise of the ADC was only 175 μV and 188 μV, and the average error of the captured sine wave data was 4.51 mV and 4.19 mV, ensuring the voltage measurement accuracy of the data acquisition units. Stability testing of the equipment in road and construction environments showed an average RSD of 2.86% and 2.92%, respectively, indicating good stability of the measurements. ZigBee network performance tests in three simulated environments and a field test showed that the packet loss rate (PLR) was less than 2% from 0 to 50 m, ensuring network communication in grouting project scenarios. On-site experiments demonstrate that the system can simultaneously monitor multiple profiles and perform inversions in the grouting area, which can be assembled into 3D inversion images for evaluating grout diffusion, offering valuable insights for optimizing construction operations, and enhancing grouting efficiency. Full article

To fully utilize the reactive power resources of distributed photovoltaic (PV) systems, this study proposes a coordinated var-voltage control strategy for the main distribution network, incorporating the reactive power regulation capability of distributed PV. Firstly, the Automatic Voltage Control (AVC) tertiary and secondary voltage control methods and optimization models in the main and distribution networks area are analyzed, and the physical equivalence of the reactive power compensation equipment involved is carried out. In this study, a coordinated local var-voltage control method is proposed, which integrates AVC primary voltage control and divides the control scheme into feeder and station areas, respectively. Through the analysis of actual operation cases in a regional power grid, the results demonstrate a reduction in network loss by 171.14 kW through voltage adjustment, validating the effectiveness of the proposed strategy. This method fully leverages the reactive power regulation capability of distributed renewable energy sources, reduces the operational frequency of reactive power equipment in substations, and synergizes with the AVC system to achieve optimal power grid operation. Full article

With the increasing penetration of distributed photovoltaics (PVs) in distribution networks (DNs), issues like voltage violations and fluctuations are becoming more prominent. This paper proposes a spatio-temporal adaptive voltage coordination control strategy involving multiple timescales and multi-device collaboration. Aiming at the heavy workload caused by the continuous sampling of real-time data in the whole domain, an intra-day innovative construction of intra-day minute-level optimization and real-time adaptive control double-layer control mode are introduced. Intra-day minute-level refinement of on-load tap changer (OLTC) and step voltage regulator (SVR) day-ahead scheduling plans to fully utilize OLTC and SVR voltage regulation capabilities and improve voltage quality is discussed. In real-time adaptive control, a regional autonomy mechanism based on the functional area voltage quality risk prognostication coefficient (VQRPC) is innovatively proposed, where each functional area intelligently selects the time period for real-time voltage regulation of distributed battery energy storage systems (DESSs) based on VQRPC value, in order to improve real-time voltage quality while reducing the data sampling workload. Aiming at the state of charge (SOC) management of DESS, a novel functional area DESS available capacity management mechanism is proposed to coordinate DESS output and improve SOC homogenization through dynamically updated power–capacity availability (PCA). And vine model threshold band (VMTB) and deviation optimization management (DOM) strategies based on functional area are innovatively proposed, where DOM optimizes DESS output through the VMTB to achieve voltage fluctuation suppression while optimizing DESS available capacity. Finally, the DESS and electric vehicle (EV) cooperative voltage regulation mechanism is constructed to optimize DESS capacity allocation, and the black-winged kite algorithm (BKA) is used to manage DESS output. The results of a simulation on a modified IEEE 33 system show that the proposed strategy reduces the voltage fluctuation rate of each functional area by an average of 36.49%, reduces the amount of data collection by an average of 68.31%, and increases the available capacity of DESS by 5.8%, under the premise of a 100% voltage qualification rate. Full article

Polycarbonate (PC) is a highly recyclable thermoplastic with high impact strength that bodes well to re-melting extrusion and shredding for positive environmental impact. For the goal of improving impact strength further, layered carbon fiber (CF) reinforcement has been added between PC sheets by hot pressing at 6.0 MPa and 537 K for 8 min. An addition of cross-weave CF layer reinforcement to PC increased Charpy impact value, a_uc of the untreated [PC]₄[CF]₃ composite over that of untreated PC resin reported at all accumulative probabilities, P_f. At medial-P_f of 0.50, a_uc was increased 3.13 times (213%), while statistically lowest impact value a_s at P_f = 0 calculated by 3-parameter Weibull equation was boosted 2.64 times (164%). To optimize a_uc, effect of homogeneous electron beam irradiation (HLEBI) treatment of 43.2, 129, 216, 302, or 432 kGy at 170 kV acceleration voltage to the CF plies before assembly with PC then hot press was also investigated. The 216 kGy HLEBI dose appears to be optimum, raising a_s at P_f = 0 about 6.5% over that of untreated [PC]₄[CF]₃ and agrees with a previous study that showed 216 kGy to be optimum for static 3-point bending strength, when quality can be controlled. Electron spin resonance (ESR) data confirms 216 kGy HLEBI generates strong peaks in CF and PC indicating dangling bond (DB) generation. Bending strength increase was higher than that of impact due to lower test velocity and higher deformation area spreading along specimen length, allowing more DBs to take on the load. X-ray photoelectron spectroscopy (XPS) data of CF top ~10 nm surface layer in the sizing confirms C–O–H, C–H, and C–O peak height from 216 kGy exhibited little or no change compared with untreated. However, 432 kGy increased the peak heights indicating enhanced adhesion to PC. However, 432 kGy degraded a_s at P_f = 0 of the [PC]₄[CF]₃, and is reported to decrease impact strength of PC itself by excess dangling bond formation. Thus, the 432 kGy created increased PC/CF adhesion, but degraded the PC resin. Therefore, 216 kGy of 170 kV-HLEBI appeared to be a well-balanced condition between the PC-cohesive force and PC/CF interface adhesive force when fabricating [PC]₄[CF]₃. Full article

In practical engineering, it has been observed that increasing local generators’ capacity in receiving-end power grids can lead the system to transition from voltage instability to power angle instability after a fault. This contradicts the typical engineering experience, where increasing the generators’ capacity at the receiving end is expected to enhance voltage stability, making it challenging to define an appropriate pre-control range for generators. This paper aims to quantify the impact of local generators on the stability of AC/DC receiving-end power grids. First, the paper describes the instability phenomena observed under different generators’ capacity conditions in actual AC/DC receiving-end power grids. Next, by using a simplified single-machine-load-infinite-bus model, the paper explores how the system’s instability characteristics evolve from being dominated by load instability to being driven by generator instability as the ratio of local generators to load varies. This study conducts an in-depth analysis of the coupling mechanism between power angle stability and voltage stability. For the first time, it quantitatively characterizes the stable operating region of the system using power angle and induction motor slip as dual constraint conditions, providing a new theoretical framework for power system stability analysis. Additionally, addressing the lack of quantitative research on the upper limit of generator operation in current systems, this study constructs post-fault power recovery curves for loads and DC power sources. Based on the equal-area criterion, it proposes a quantitative index for the upper limit of local generator operation, filling a research gap in this field and providing a crucial theoretical basis and reference for practical power system operation and dispatch. Full article

The high proportion of distributed photovoltaics (PVs) connected to distribution substation areas causes complex operation of the medium- and low-voltage distribution network. New power electronic devices represented by soft open point (SOP) can achieve a flexible interconnection between distribution substation areas. In this paper, a cooperative operation optimization method for medium- and low-voltage distribution networks considering flexible interconnected distribution substation areas is proposed. Firstly, interval affine is used to model the resource aggregation and obtain the flexibility region constraints of distribution substation areas. Then, a multi-scale cooperative operation framework for medium- and low-voltage distribution networks is constructed. The medium-voltage distribution network adopts the centralized method to solve and issue operation strategy instructions. The distribution substation area generates a voltage-reactive power adaptive regulation curve and performs intra-day rolling control. Finally, the case studies show that the proposed method has efficient operation strategy of medium- and low-voltage distribution networks and can alleviate the voltage fluctuation caused by high integration of PVs. Full article