Direct Power Research Articles

Enhanced Wind-Field Detection Using an Adaptive Noise-Reduction Peak-Retrieval (ANRPR) Algorithm for Coherent Doppler Lidar

Wind fields provide direct power for exchanging energy and matter in the atmosphere. All-fiber coherent Doppler lidar is a powerful tool for detecting boundary-layer wind fields. According to the characteristics of the lidar echo signal, an adaptive noise-reduction peak retrieval (ANRPR) algorithm is proposed in this study. Firstly, the power spectrum data are divided into several continuous range gates according to the time series. Then, the adaptive iterative reweighted penalized least-squares (airPLS) method is used to reduce the background noise. Secondly, the continuity between spectra is enhanced by 2D Gaussian low-pass filtering. Finally, an adaptive peak-retrieval algorithm is employed to extract the Doppler shift, facilitating the synthesis of a spatial atmospheric 3D wind field through the vector synthesis method. When comparing data from different heights of the meteorological gradient tower, both the horizontal wind-speed correlation and the horizontal wind-direction correlation exceed 0.90. Experimental results show that the proposed algorithm has better robustness and a longer detection distance than the traditional algorithm.

The Relationship Between Inter-Legality and Organized Social Processes in Land Formalization Practices in The Sovereignty-Contested Area of Tanintharyi Region, Myanmar

The study considers the Dawei Special Economic Zone (DSEZ) project, which was a land formalization case in a sovereignty-contested area conducted by de jure Myanmar state, de facto Karen Nation Union (KNU), and an international developer. The DSEZ project planning comprised deep-sea Ports, 250 sq. kms of industrial estate zone, and the two-lane 148 km road linking Dawei in Myanmar and Kanchanaburi Province of Thailand as its main features. Recent studies of Myanmar land institutions in sovereignty-contested areas have mainly discussed the factor of "inter-legality," the integration of non-state land laws, as the solution for land disputes between the central state and armed ethnic political groups. However, the real-world case in this study indicated a second factor, "organized social processes," working in correspondence with the first factor. This research paper explores how the two factors were used together the integration of customary land practice into statutory property institutions, influencing changes in the structure and process of land formalization practices, and illustrates the unclear property institutions of sovereignty-contested frontiers. This research paper is a single case study that benefited from the researcher's five years of work experience in the DSEZ project's design, planning, and land acquisition. The obtained information comprises the project's land formalization documentation, published land laws which were checked with the project manager using the triangulation method, and local newspaper clippings. The study concludes that inter-legality and organized social processes should be used together in practice planning to form more context-oriented land formalization practices, employing collective community memory to reduce institutional inertia. Furthermore, the mutually-agreed standards can help avoid direct power contestation between the de jure and de facto.

Soliton molecules order control and their propagation features in an anomalous dispersion optical fiber

We report the experimental generation of soliton molecules (SM) with a controlled number of pulses in an all-fiber erbium laser. The change in the number of pulses (from 7 to 18 coupled states) occurred without changing time- separation between pulses. The ability to increase or decrease the number of pulses is repeatable and easily controlled by changing the pump power in both directions without changing the output characteristics of the reported regime. The average pulse duration was < 0.5 ps at full width at half maximum with a time interval between pulses of ∼ 4.7 ps.We also experimentally and numerically studied the evolution of soliton molecules regime with N = 23 during propagation along a standard telecommunication fiber with anomalous dispersion. In this case, we observed the appearance of a dispersive wave, which led to a rapid broadening of the pulses and the subsequent decay of the SM.

Research on downhole visible light modeling and localization based on point cloud technology

In this paper, we reconstruct the downhole visible light channel model based on point cloud technology. To make up for the defect that the reflective surface element is a virtual surface, the planar projection method and the idea of point-by-point insertion are combined to turn the point cloud data on the wall surface into a triangular mesh topology. In the meantime, the point cloud data of obstacles is utilized to determine the precise range of shadows cast by light. Subsequently, shadow coefficients are defined to derive new expressions for channel gain. In addition, the localization in a 6 m × 4 m × 3 m space is achieved through the utilization of the particle swarm algorithm optimized BP neural network (PSO-BP) localization algorithm. In scenarios where the walls exhibit unevenness and barriers are present, the root mean square positioning error is found to be 6.52 cm when taking primary reflection into consideration. Conversely, when solely relying on direct power, the positioning error increases to 9.92 cm. Consequently, it is important to consider the non-line-of-light (NLOS) link when conducting downhole visible light localization.

Automated acoustic monitoring of fish for near-real-time resource management

Abstract Freshwater fisheries in developing regions provide livelihoods and nutrition for millions of people worldwide. These fisheries are frequently data poor, which limits fisheries management. The seasonal Cambodian dai platform fishery on the Tonle Sap River is one of the best monitored inland fisheries in Southeast Asia, yet catch sampling is limited and there is no fishery-independent monitoring. A monitoring system is needed to characterize fish migration and mortality, be cost effective, and be deployable in areas with minimal infrastructure. We integrated a Simrad wide-band transceiver mini echosounder (200 kHz), solar power, and an Internet of Things communications module as an autonomous, automated monitoring package for the deployment on upstream and downstream commercial fishing platforms. The solar panel and controller supply direct current power to the echosounder, communications module, and battery for power during dark hours. Echosounders are programmed to sample at 1 Hz for 15 min every hour. The communications module is a built cellular endpoint that accesses a local wireless network to transmit raw data files to a data server. Data are downloaded from the server for processing and analysis. This expandable system provides a flexible management tool that can be deployed at any location with wireless communication capability.

A Digital Twin-Based Approach for the Optimization of Floor-Ball Manufacturing

The increasing complexity of products and manufacturing processes, combined with the constantly advancing technological integration of the manufacturing sector, raised new challenges for world-class industries to optimize time-to-market, resources, and cost. Simulation, as an essential Industry 4.0 enabling technology, allows one to emulate the steps of a manufacturing process, thereby achieving significant improvements in all the product and process development phases. A simulation process can be implemented and improved by creating the Digital Twin of the manufacturing system, which can be realized on a single-line scale or extended to the whole factory. The Digital Twin merges physics-based system modeling and real-time process data to generate a virtual copy of an observable object to reduce and optimize the extensive time and cost of physical design, prototyping, commissioning, reconfiguration, and maintenance. This study aims to investigate how the implementation of digital twin technology can help optimize the balance between power consumption and productivity, taking into account existing barriers and limitations. By following this outline, this study shows the design and development of a digital twin for a floor-ball manufacturing line present in the Smart Factory of Ostschweizer Fachhochschule (Switzerland). The entire production process is reproduced with Siemens Technomatix Plant Simulation software 2201, and data connection and processing are handled by a tailored toolchain consisting of an agent, a database, Python packages, and the COM interface from Tecnomatix. This toolchain feeds the digital twin with data from the physical operating environment. In particular, this study compares direct power measurements with the ones expected by the digital twin to assess digital model accuracy.

PV System Linked to an Electrical Network with an Active Power Filter Using DPC Modified Method Under Distorted Grid Voltage Conditions

This article presents an energy system that enhances the quality of electrical energy by injecting photovoltaic (PV) renewable energy into the electrical network in the presence of a polluting load. This system is based on a new control approach known as Zero Direct Power Command (ZDPC). The innovative aspect of the proposed work is the addition of clean energy while simultaneously removing the unsettling harmonics produced by the nonlinear loads provided by distorted voltages. This approach combines a traditional Proportional Integrator (PI) controller for regulating the DC bus voltage with a clever technique (fuzzy logic) for tracking the Maximum Power Point Tracking (MPPT). The current has a harmonic distortion rate of about 1% with unity power factor due to the suppression of undesirable harmonics from the source currents. A PV panel connected in series with a chopper and managed by fuzzy logic via a two-state inverter ensures the injection of PV energy into the electrical network. Software called MATLAB/Simulink is used to model this system. The outcomes demonstrate the reliability and viability of the ZDPC control, which concurrently ensures harmonic current compensation, power factor correction, and the introduction of solar power into the electrical network despite distorted source voltages.

Investigation of SAR reduction and gain enhancement using an all-textile antenna with metamaterial structure for wireless body area network applications

This work presents a wideband, low-profile, and flexible antenna that incorporates metamaterial (MTM) structures and textile materials. The antenna design is simulated using CST Microwave Studio, incorporating flexible textile elements such as a felt substrate and conductive fabric. The developed antenna's performance was examined numerically in free space and on a human body. The antenna with MTM technology operates in the ultra-wideband (UWB) with a bandwidth ranging from 3.86 to 13 GHz. It possesses a low profile with a thickness of 5.34 mm, making it suitable for applications in wireless body area networks (WBAN). Through the integration of metamaterial structures, the antenna's gain is enhanced, reaching 8.85 dBi compared to the initial gain of 5.34 dBi. Notably, the gain consistently exceeds 6 dBi across the entire UWB range, indicating focused power in a specific direction. For applications on the human body, specific absorption rate (SAR) values were calculated and found to be well within safety limits defined by European standards. This ensures minimal back radiation when the antenna is worn on the body, enhancing signal transmission range in WBAN applications.

A Comprehensive Flowchart to Maximize the Outcome of Direct Power Injection Tests

A Comprehensive Flowchart to Maximize the Outcome of Direct Power Injection Tests

Design and PIL implementation of a new robust backstepping based low-complexity voltage-oriented control method for four-leg rectifiers

This paper proposes a low computational complexity enhanced voltage-oriented control strategy (EVOC) based on robust backstepping controllers (BSC) in the synchronous rotating frame (dq0 frame) for a PWM four-leg voltage-source-rectifier (FLVSR). Unlike traditional VOC strategies, the suggested EVOC approach does not need any synchronization method and Park transformations, and it has the similar architecture and same features as the traditional VOC when it’s synchronization loop for grid voltage phase angle detection is properly operated. In addition to controlling the FLVSR, the suggested EVOC strategy is also used to develop the model of the three phase FLVSR in the dq0 frame using the concepts of direct instantaneous power control (DPC) theory, which combine the benefits of traditional DPC and traditional VOC with less computational complexity. The robust BSC is adopted for accurate regulation of FLVSR input currents and dc bus voltage simultaneously while taking into account the FLVSR parameter uncertainties. It produces sinusoidal currents with lower ripples and has high robustness against parametric variations. It is also simple to implement and has a relatively high grid voltage disturbance rejection ability. Finally, comparisons with both the traditional VOC strategy using PI controllers (VOC-PIC) and the EVOC strategy using PI controllers (EVOC-PIC) under various conditions demonstrate the superiority and benefits of the proposed EVOC-BSC strategy.

Direct carbon dioxide-methane solid oxide fuel cells combined with in-situ exsolution perovskite La0.75Sr0.25Cr0.5Fe0.4Cu0.1O3-δ-based dry reforming catalysts

In response to greenhouse effect and energy crisis, the clean and efficient use of CH4 and CO2 resources has become increasingly attractive. Against this background, solid oxide fuel cells (SOFCs) have become one of the research hotspots due to the possibility of utilizing methane and carbon dioxide for the conversion into syngas (H2 and CO) for efficient direct power generation. In this study, we propose to dope Cu into La0.75Sr0.25Cr0.5Fe0.5O3-δ to enhance the catalytic activity for direct carbon dioxide-methane dry reforming reactions. In wet hydrogen conditions, Fe nanoparticles can effectively exsolve from La0.75Sr0.25Cr0.5Fe0.4Cu0.1O3-δ (LSCFC), which is beneficial for the dry reforming reaction of methane. With the LSCFC-Ce0.9Gd0.1O2-δ (LSCFC-GDC) composite reforming layer, the anode-supported single cells exhibited remarkable electrochemical performance. When fueled with both H2 and CH4–CO2, the maximum power densities achieved 608.3 and 497.1 mW cm−2 at 800 °C, with corresponding polarization resistance values of 0.35 and 1.11 Ω cm2, respectively. Furthermore, the single cells with LSCFC-GDC reforming layer showed excellent carbon tolerance, maintaining stable performance for 120 h using 50%CH4–50%CO2. Our results demonstrate the use of dry reforming catalysts in SOFCs is effective in both enhancing CH4–CO2 reforming efficiency and maintaining carbon tolerance.

The Mitigation of Interference on Underground Power Lines Caused by the HVDC Electrode

High Voltage Direct Current power links are usually designed to adopt, on a continuous basis or during emergency operations, two grounding plants using the soil or seawater as a link–current return path. Such DCs flowing into the ground can cause problems, of which one of the most important is the increased risk of the corrosion of metallic structures in the area. Normally, the simplest mitigation technique is to keep an adequate distance between the main grounding plants and any metallic structure that can be corroded. Normally, such distances are not less than 5 km. However, there are situations where this approach cannot be applied, for example due to geographical constraints. In this paper, we describe and analyze the behavior of a mitigation technique that can be adopted when the HV pole cable is laid closer than the recommended distance to the main ground electrode. This paper is focused on the minimization of deleterious effects on the cable’s metallic sheath and its earthing points, distributed along it by means of sheath segmentation. The suggested approach appears well-suited to substantially diminishing the current flowing through the sheath of an HVDC power cable. In the segmented scenario, the sheath’s power dissipation is less than one-hundredth of that in the typical continuous configuration.

Fuzzy adaptive dP-perturb and observe maximum power point tracking controller for wind energy conversion systems: Design and real-time implementation

This paper proposes a novel Maximum Power Point Tracking (MPPT) technique for Wind Energy Conversion Systems (WECS) for fast environmental changing conditions. This technique is a direct power control hill-climbing method called dP-P&O (Perturb and Observe) with online perturbation step size scheduling using a fuzzy inference system based on the two successive power variations to perform quick convergence with high precision until reaching the MPP. The Fuzzy Adaptive dP-P&O (FAdP-P&O) is proposed to overcome the drawbacks of the classical dP-P&O and ameliorate its control performances. The dP-P&O and FAdP-P&O are experimentally evaluated in a WECS emulator test bench controlled dSPACE DS1104, where the experimental results prove that the proposed algorithm guarantees the desired performances with high energy quality and great robustness against speed or load change.

Swimmable Micro‐Battery for Targeted Power Delivery

AbstractThe boom of microelectronic devices and their diverse applications has heightened the demand for innovative and effective energy supply strategies. The longevity of contemporary microelectronic devices predominantly depends on direct human intervention power supply methods, encompassing battery replacement or recharging. However, these methods may falter in specific scenarios, such as when facing liquid conditions in vivo. Here, a concept of swimmable micro‐batteries (MBs) for targeted power delivery is presented. This is achieved through the design of a flexible polydimethylsiloxane/Fe3O4 soft‐magnetic substrate for actuation, polydimethylsiloxane/neodymium‐iron‐boron (NdFeB) hard‐magnetic tabs for precise targeting, and quasi‐solid‐state Zn//MnO2 battery for power generation. These swimmable MBs exhibit an impressive areal capacity of 102.3 µAh cm‐2, remarkable waterproofing, adjustable output voltage or capacity, rapid response, and accurate remote magnetic field manipulation, enabling targeted power supply available. This novel swimmable MB design broadens the function of MBs and may open a new avenue for their future development.

The optimal allocation of H-SFCL in MVDC SPS

Medium voltage direct current shipboard power system (MVDC SPS) is the development trend of navy in the future. At present, one of the bottlenecks restricting the development of MVDC SPS is that the short fault. There is a lack of effective means to limit short fault current to protect MVDC SPS. This paper presents a method of applying a hybrid type superconducting fault current limiter (H-SFCL) to MVDC SPS protection. The architecture and system modeling of MVDC SPS are introduced, and the mechanism of bipolar DC short fault is analyzed. The topology and working principle of H-SFCL are introduced. The small-scale prototype experiment is done, the current limiting effect of H-SFCL is compared with resistive type superconducting fault current limiter (R-SFCL) and flux-coupling type superconducting fault current limiter (FC-SFCL) in the prototype test, so as to verify the superiority of H-SFCL. A dual objective hierarchical optimization configuration method is proposed, and the number and position of H-SFCLs are verified on a four-terminal system, as well as multi-objective optimization for H-SFCLs. A fault isolation and H-SFCL optimal allocation evaluation model is proposed; An improved method suitable for fault isolation and multi-objective optimal allocation of H-SFCLs is proposed to address the issue of breaking timing between internal switches in H-SFCLs and external circuit breakers in the optimization process. The research results indicate that the proposed optimal allocation method can optimize the inductance, resistance, and switch breaking time inside the current limiter, and can match the timing with the external circuit breaker; The proposed multi-objective optimization configuration method has a maximum effective individual ratio of 88% in the first 20 generations of improvement, and the improved iteration speed has significantly increased. In the 5th generation, the effective individual ratio can reach 100%.

Direct current power system stabilizers for HVDC grids: Current status

AbstractA power system stabilizer (PSS) is a control system integrated into the control structure of specific generation units within AC grids. It monitors current, voltage, and machine shaft speed. Analysing these variables, the PSS generates appropriate control signals to the voltage regulator unit, aiming to damp system oscillations. With the advancement of high‐voltage direct current (HVDC) overlaid high‐voltage alternative current (HVAC) grids, it is anticipated that direct current power system stabilizers (DC‐PSS) will be developed to perform a similar role as their AC counterparts. DC‐PSS will be responsible for monitoring and controlling DC voltage levels, ensuring stable operations. This paper focuses on DC‐PSS in HVDC grids, designed to ensure stable operation and mitigate voltage fluctuations. Unlike conventional AC power systems, HVDC includes only DC voltage and power. The input signal for DC‐PSS is the variations in DC voltage, and the output signal is proportional to the power changes at the specific bus where the DC‐PSS is installed, aiming to minimize DC voltage oscillations. These characteristics pose significant challenges in DC‐PSS. The paper addresses the challenges and highlights issues such as inertia and low‐frequency oscillations associated with DC‐PSS. Various control methods are presented and a comparison is made among these methods.

High Performance of Direct Power Control for a Doubly Fed Induction Generator Based on Adaptive Fuzzy Second Order Sliding Mode Controller in Wind Energy Conversion System

High Performance of Direct Power Control for a Doubly Fed Induction Generator Based on Adaptive Fuzzy Second Order Sliding Mode Controller in Wind Energy Conversion System

Passive power management for triboelectric nanogenerators in sub-microwatt applications

Triboelectric nanogenerators (TENGs) have been regarded as a promising enabling technology for self-powered applications. However, their inherent characteristics, such as high internal impedance and high output voltage, not only make them unsuitable to be used as a direct power source but also create substantial challenges in power management for low-power applications. To date, effective power management systems have not been available for sub-microwatt applications. In this study, we propose a passive power management system for such extremely low-power scenarios. The system can effectively condition the electricity generated by a TENG into a form compatible with standard electronic devices, which can then be stored on an energy storage device. We demonstrate that for TENGs using a liquid metal drop, the power management system can transfer up to 85% of the electricity generated to the storage when the power output of the TENG is below 1 μW. For TENGs using a water drop, the energy transfer efficiency can reach a remarkably high level of 80% when the TENG harvests as low as 38 nJ of energy per cycle.

Electrochemical anodization of cast titanium alloys in oxalic acid for biomedical applications

Titanium and its alloys have numerous biomedical applications thanks to the composition and morphology of their oxide film. In this study, the colorful oxide films were formed by anodizing cast Ti-6Al-4V and Ti-6Al-7Nb alloys in a 10% oxalic acid solution for 30 s at different voltages (20–80 V) of a direct current power supply. Atomic force microscopy was used as an accurate tool to measure the surface roughness of thin films on the nanometer scale. Scanning electron microscopy and X-ray diffraction were performed to analyze surface morphology and phase structure. According to the results, the produced titanium oxide layer showed high surface roughness, which increased with increasing anodizing voltage. The impact of anodizing voltages on the color and roughness of anodized layers was surveyed. The corrosion resistance of the anodized samples was studied in simulated body fluid at pH 7.4 and a temperature of 37 °C utilizing electrochemical impedance spectroscopy and the potentiodynamic polarization method. The anodized samples for both alloys at 40 V were at the optimal voltage, leading to a TiO2 layer formation with the best compromise between oxide thickness and corrosion resistance. Also, findings showed that TiO2 films produced on Ti-6Al-7Nb alloys had superior surface roughness properties compared to those of Ti-6Al-4V alloys, making them more appropriate for orthopedic applications. From the obtained data and the fruitful discussion, it was found that the utilized procedure is simple, low-cost, and repeatable. Therefore, anodization in 10% oxalic acid proved a viable alternative for the surface finishing of titanium alloys for biomedical applications.

Bacterial quorum sensing orchestrates longitudinal interactions to shape microbiota assembly

BackgroundThe mechanism of microbiota assembly is one of the main problems in microbiome research, which is also the primary theoretical basis for precise manipulation of microbial communities. Bacterial quorum sensing (QS), as the most common means for bacteria to exchange information and interactions, is characterized by universality, specificity, and regulatory power, which therefore may influence the assembly processes of human microbiota. However, the regulating role of QS in microbiota assembly is rarely reported. In this study, we developed an optimized in vitro oral biofilm microbiota assembling (OBMA) model to simulate the time-series assembly of oral biofilm microbiota (OBM), by which to excavate the QS network and its regulating power in the process.ResultsBy using the optimized OBMA model, we were able to restore the assembly process of OBM and generate time-series OBM metagenomes of each day. We discovered a total of 2291 QS protein homologues related to 21 QS pathways. Most of these pathways were newly reported and sequentially enriched during OBM assembling. These QS pathways formed a comprehensive longitudinal QS network that included successively enriched QS hubs, such as Streptococcus, Veillonella-Megasphaera group, and Prevotella-Fusobacteria group, for information delivery. Bidirectional cross-talk among the QS hubs was found to play critical role in the directional turnover of microbiota structure, which in turn, influenced the assembly process. Subsequent QS-interfering experiments accurately predicted and experimentally verified the directional shaping power of the longitudinal QS network in the assembly process. As a result, the QS-interfered OBM exhibited delayed and fragile maturity with prolonged membership of Streptococcus and impeded membership of Prevotella and Fusobacterium.ConclusionOur results revealed an unprecedented longitudinal QS network during OBM assembly and experimentally verified its power in predicting and manipulating the assembling process. Our work provides a new perspective to uncover underlying mechanism in natural complex microbiota assembling and a theoretical basis for ultimately precisely manipulating human microbiota through intervention in the QS network.1Pt_u9XsUgt5LaXgu9Dt3MVideo