Search Results (47,944)

With the increasing integration of large-scale renewable energy sources, the coordinated participation of hydropower and energy storage in frequency regulation has become a critical means of ensuring the safe and economical operation of power grids. This paper proposes an optimization method for the allocation of frequency regulation reserves between hydropower and energy storage based on marginal substitution rate (MRS) analysis. First, a frequency response model that captures the synergistic interaction between hydropower and energy storage is established, with the root mean square error (RMSE) of the area control error (ACE) serving as the performance metric for frequency regulation. To reduce simulation computational burdens, key simulation data are obtained via Gaussian process regression (GPR), and a piecewise polynomial fitting method is employed to generate the marginal substitution curve. Experimental results indicate that under the condition of achieving equivalent frequency regulation performance (ACE_RMSE), 51.60 MW of energy storage reserve can replace 68.38 MW of hydropower reserve, thereby reducing the total regulation capacity reduction of 13.42%. Furthermore, by incorporating the differing cost characteristics of hydropower and energy storage, the optimal configuration is determined, resulting in an overall cost reduction of 17.58%. This method not only ensures system frequency stability but also fully leverages the potential of the available frequency regulation resources. Full article

Originally proposed by the authors, the spring pendulum pounding-tuned mass damper (SPPTMD)—a novel nonlinear damping system comprising a spring pendulum (SP) and motion limiter that dissipates energy through spring resonance amplification and controlled mass-limiter impacts—was theoretically validated for structural vibration control. To experimentally verify its efficacy, a two-story, lightly damped steel frame was subjected to sinusoidal excitation and historical earthquake excitations under both uncontrolled and SPPTMD-controlled conditions. The results demonstrated (1) significant vibration attenuation through SPPTMD implementation and (2) enhanced control effectiveness in soft soil environments compared to stiff soil conditions. Additionally, a numerical model of the SPPTMD–structure system was developed, with computational results showing excellent correlation to experimental data, thereby confirming modeling accuracy. Full article

Flexible piezoresistive pressure sensors have great potential in wearable electronics due to their simple structure, low cost, and ease of fabrication. Porous polymer materials, with their highly deformable internal pores, effectively expand the sensing range. However, a single-sized pore structure struggles to achieve both high sensitivity and a broad sensing range simultaneously. In this study, a PDMS-based flexible pressure sensor with a bilayer porous structure (BLPS) was successfully fabricated using clamping compression and a sacrificial template method with spherical sucrose cores. The resulting sensor exhibits highly uniform pore sizes, thereby improving performance consistency. Furthermore, since different pore sizes and thicknesses correspond to varying Young’s moduli, this study achieves tunable sensitivity across a wide pressure range by adjusting the bilayer thickness ratio (maximum sensitivity of $0.063 {\mathrm{kPa}}^{-1}$ in the 0–23.6 kPa range, with a pressure response range of 0–654 kPa). The sensor also demonstrates a fast response time (128 ms) and excellent fatigue stability (>10,000 cycles). Additionally, this sensor holds great application potential for facial expression monitoring, joint motion detection, pressure distribution matrices, and Morse code communication. Full article

With the aim of investigating the factors influencing the hysteretic behavior of common steel bars with unbonded sections (CS-US), hysteresis tests of six CS-US specimens were conducted, taking unbonded length, the location of the unbonded section, steel bar diameter, steel bar strength grade, and concrete strength grade as study variables. The results show that there exist necking phenomena in steel bars and different degrees of damage to concrete in all specimens. A 3D fine model was established by Solid works and ABAQUS software and verified according to the experimental results. The results show that the simulated values are close to the experimental values. Subsequent to the validation of the model, a thorough analysis was performed to assess the energy dissipation capacity and ductility of CS-US. The findings indicate that the implementation of an unbonded section can remarkably enhance the energy dissipation capacity and ductility of CS-US. It was demonstrated that the larger the unbonded length, the greater the ductility and energy dissipation capacity of CS-US. An alteration in the bonded length at the loading end exerts minimal influence on the energy dissipation capacity and ductility of CS-US. The energy dissipation capacity and ductility of CS-US decrease with an increasing steel bar diameter or strength grade. Concrete strength grades lower than C40 have minimal impact on the energy dissipation capacity and ductility of CS-US; concrete with a strength grade higher than C40 exhibits a decrease in energy dissipation capacity and ductility initially, followed by an increase. However, the values of these parameters remain lower than those observed in concrete with a strength grade below C40. Finally, the proposed design values of the above parameters are provided as a reference for engineering applications. Full article

This study presents a precise and efficient methodology for evaluating the water-richness of the aquifer overlying the No. 3 coal seam in Hancheng Mine. A comprehensive assessment model was developed by integrating subjective and objective weighting through the sequential relationship analysis–entropy value method. This model facilitated the delineation of water-richness zones within the sandstone aquifer of the Shanxi Group associated with the No. 3 coal seam. Five key evaluation indices were selected based on the aquifer’s water-richness index: core recovery rate, thickness of water-rich sandstone, number of sand–mudstone interlayers, sandstone lithology coefficient, and the thickness ratio of brittle to plastic rock. Furthermore, an advanced evaluation model combining set pair analysis and variable fuzzy sets was established to assess the water-richness risk levels across the entire Hancheng mining area. The results reveal distinct spatial patterns in water-richness: the northeastern region exhibits strong water-richness, while the southwestern area is characterized by medium to weak water-richness over a broad expanse. Overall, the No. 3 coal seam in the Hancheng mining area is classified as having a medium risk level of water-richness. Full article

In this study, the effective radius of aerosol particles was experimentally retrieved using a self-developed dual-wavelength atmospheric aerosol lidar. A single-valued lookup table was first established, based on the OPAC database and the Gamma size distribution model, to define the relationship between the extinction coefficient ratio and the effective radius of atmospheric aerosol particles. The extinction coefficients corresponding to the 355 nm and 1064 nm wavelengths were then calculated using the echo signals retrieved horizontally by the lidar, in conjunction with the Mie scattering lidar equation. Subsequently, the lookup table was used to retrieve the real-time effective radius of aerosol particles by inputting the extinction coefficient ratio of the two wavelengths. Finally, the retrieval results were compared with the effective radii measured by an optical particle spectrometer, which had been corrected for relative humidity. An analysis over six months showed a coefficient of determination (R²) greater than 0.83. The results demonstrated that the dual-wavelength lidar exhibits a stable performance, the retrieval method is valid, and the detection results are accurate and reliable. Full article

Background: The three commercial Enterovirus 71 (EV71) inactivated vaccines which have effectively controlled the EV71 pandemic currently rely on inherent variable in vivo potency methods for batch release. To align with 3R (Replacement, Reduction, Refinement) principles and enhance quality control, this study referred to WHO guidelines and the European Pharmacopoeia to develop in vitro relative potency (IVRP) methods. Methods: Working standards tracing to phase 3 clinical vaccines were established. Manufacture-specific IVRP methods were developed and validated per ICH Q14/Q2(R2), utilizing conformational epitope-targeting neutralizing monoclonal antibodies (MAbs). One of the MAbs (CT11F9) recognition sites was clarified with Cryo-EM. Subsequently, the performance of IVRP was assessed using varied concentrations and heat-treated vaccines. The correlation between IVRP and in vivo methods was analyzed, followed by setting IVRP specifications. Results: The manufacturer-specific working standard exhibited ED50 values comparable to those of related phase 3 clinical vaccines. All IVRP methods achieved a relative bias/precision/total error ≤ 15%. The IVRP methods correlated with in vivo methods (p < 0.05, r > 0.9) can discriminate EV71 antigen concentrations (p < 0.01, r > 0.99) and indicate the stability of the vaccines. Cryo-EM was adopted to identify the epitopes recognized by CT11F9, revealing that this neutralizing antibody recognizes a conformational epitope spanning VP1-3 of the same protomer. Using 31–47 batches of commercial vaccines, IVRP specifications were proposed as 0.56–1.35, 0.58–1.40, and 0.54–1.50. Conclusions: Based on conformational epitope-targeting neutralizing MAbs, manufacturer-specific IVRP methods, which were sensitive to process variations and correlated with in vivo results, have been established. IVRP methods provide a reliable, animal-free alternative for EV71 vaccine batch release. Full article

Laboratory simulation of aging cannot restore the complex aging behavior of bitumen well. The objective of study is to reveal the role of various field aging factors on the aging process of virgin bitumen and SBS(Styrene–Butadiene–Styrene)-modified bitumen. The influence of different field aging factors on aging behavior of virgin bitumen and SBS-modified bitumen were discussed. To achieve this goal, three different field aging styles were used to carry out field aging of virgin bitumen and SBS-modified bitumen. The aging behavior of the two types of bitumen were characterized based on rheological performance, and the influence degree of various aging factors on the rheological performance of bitumen was quantitatively analyzed through the contribution rates. The findings indicated that field aging had an obvious influence on the rheological performance of the two types of bitumen, which showed that the complex modulus, G-R parameter and stiffness modulus increased, and creep rate decreased. The contribution rates significantly indicated the degree of influence of hot oxygen, light and other factors (wind, water, dust, etc.) on the two types of bitumen. Among them, hot oxygen was the main factor leading to the aging of two types of bitumen. The virgin bitumen was not sensitive to aging caused by light, and the aging of SBS-modified bitumen was greatly affected by light. Other field aging factors (wind, water, dust, etc.) led to the aging of virgin bitumen to a certain extent, but inhibited the aging of SBS-modified bitumen. Full article

Low-cost powdered activated coke (PAC) produced by a one-step rapid method with lignite was used as an adsorbent for the advanced treatment of phenol-containing wastewater to evaluate the feasibility of replacing high-cost commercial powdered activated carbon. Characterization using infrared spectral analysis, SEM, and BET showed that the PAC mesopores were well developed. PAC exhibited a high adsorption performance for phenol in static experiments. The adsorption was almost in equilibrium within 20 min, and the removal efficiency reached 85.4% with 1.5 g L⁻¹ PAC and 99.9% with 4 g L⁻¹ PAC. As common components in wastewater, NaCl and Na₂SO₄ did not exhibit significant competitive adsorption with phenol in PAC. The adsorption process occurred in accordance with the Langmuir model and the pseudo-second order kinetic model. Furthermore, the effects of hydrothermal regeneration on PAC adsorbing phenol were studied, and the adsorption capacity of PAC after five regeneration cycles was 86.1% of that of the new PAC, which still had good adsorption performance. PAC offers significant advantages in terms of adsorption capacity, economic feasibility, regeneration, and recycling, providing a practical solution to the problem of phenol-containing wastewater pollution. Full article

With the growing global focus on sustainable development and climate change mitigation, promoting the low carbonization of energy systems has become an inevitable trend. Power load monitoring is crucial to achieving efficient power management, and load identification is the key link. The traditional load identification method has the problem of low accuracy. It is assumed that the technique of fusing harmonic features through color coding can improve the accuracy of load identification. In this paper, the load’s instantaneous reactive power, power factor and current sequence distribution characteristics are used as the mapping characteristics of the R, G and B channels of the two-dimensional V–I trajectory color image of the load using color coding technology. The harmonic amplitude characteristics are integrated to construct the mixed-color image of the load. The void residual shrinkage neural network is selected as the classification training model. The advantages and disadvantages of two residual shrinkage construction units, RSBU-CS and RSBU-CW, are analyzed. A single-load identification model with three RSBU-CWs is built. Different datasets verify the performance of the model. Compared with the test results of the ordinary color image dataset, the accuracy of the mixed-color image dataset is above 98%, and the accuracy of load identification is improved. Full article

PID controllers have been dominant in the field of process control for a long time, but their control quality is not ideal and the difficulty of parameter tuning has always been a problem. MPCs have good control quality and robustness, but due to the complexity of the algorithm, most are limited to software on PC machines. Although there are examples of implementations on hardware, they are restricted to specific scenarios and are of an experimental nature. The barriers to application and maintenance are high, and therefore, it has not become as popular as PID. The common self-balancing industrial objects are approximated as a first order plus dead time (FOPDT) model, and various parameters are simplified to obtain the control law of the simplified MPC controller. The control law has a small amount of calculation, good control quality, simple parameter settings, and is suitable for embedding in the field controller. Coupled with the auxiliary identification method, field technicians can easily use it. MATLAB (2016a) comparative simulation experiments show that the simplified MPC controller has obvious control advantages over PID. The results of field engineering applications also show that the simplified MPC controller can feasibly replace the PID algorithm in industrialization. Full article

The presented in silico and phylogenetic analysis of putative endolysins potentially produced by phages infecting uropathogenic Escherichia coli (UPEC) demonstrates their remarkable diversity. These proteins exhibit significant variations in sequence length, molecular weight, isoelectric point, and stability, as well as diverse functional domains determining their enzymatic activity, including lysin, lysozyme, hydrolase, amidase, and peptidase functions. Due to their predicted lytic properties, endolysins hold great promise in combating UPEC bacteria, including those within biofilms, which are often highly resistant to conventional treatments. Despite their potential, several challenges hinder the full utilization of endolysins. These include the relatively small number of identified proteins, challenges in the annotation process, and the scarcity of studies evaluating their efficacy in vitro and in vivo against Gram-negative bacteria. In this work, we emphasize these challenges while also underlining the potential of endolysins as an effective tool against UPEC infections. Their effectiveness could be significantly enhanced when combined with agents that disrupt the outer membrane of these bacteria, making them a promising alternative or complement to existing antimicrobial strategies. Further research is necessary to fully explore their therapeutic potential. Full article

Research has delved into the main controlling factors for the evolution of the pore-fracture structure in deep coal samples. The gas content is influenced by multiple factors, among which the pore-fracture structure in deep coal samples stands as one of the key determinants. To ascertain the evolution of the pore-fracture structure and the main controlling factors of the gas content in deep coal samples of the Yan’an Gas Field, 16 coal samples were collected from the Yan’an Gas Field in the Ordos Basin in this study. A series of laboratory tests and analyses were then carried out. According to the test results, the major controlling factors for the evolution of the pore-fracture structure of the samples were analyzed in accordance with the proximate analysis components, maceral components, mineral composition of the coal samples, and R_o,max, in conjunction with the pore volume and specific surface area of nanopores. Meanwhile, based on the in situ desorption experiment, the major controlling factors of the gas content in coal were explored. First, based on the SEM and hand specimen identification, the pore-fracture structure of the samples is relatively well developed. Calcite filling the fractures of samples can be seen in the hand specimens of samples. This indicates that the mineral composition has a very important influence on the evolution of the pore-fracture structure of samples. Secondly, this study indicates that pore-fracture structure evolution is influenced by multiple factors, primarily ash content and fixed carbon. As ash content increased, the mesopore surface area and volume rose across all sample types, with Type C showing the highest increase (78.1% in surface area and 12.4% in volume compared to Type A). Conversely, micropore characteristics declined, with Type C exhibiting a 4.8% drop in surface area and a 4.7% reduction in volume. The R_o,max of the samples is generally higher than 2.8%, which has a multifaceted impact on pore-fracture structure evolution. Finally, the gas content is mainly controlled by pore volume and the specific surface area of nanopores, with industrial components and maceral compositions showing minimal direct influence. This suggests that gas content results from the combined effects of material composition and pore-fracture structure evolution. Inorganic minerals like quartz and calcite indirectly affect gas content by influencing pore structure development—occupying spaces while also creating new pores, especially through calcite dissolution. Conversely, clay minerals generally hinder pore development by filling spaces with limited fracture-forming capacity. The main purpose of this study is to evaluate the gas content of coal samples in Yan‘an Gas Field. There are few studies on this area by previous scholars. Full article

Due to the fracture caverns in fractured-vuggy reservoirs, channeling frequently occurs during water injection or gas injection. The stability of the oil–water/oil–gas interface during water injection or gas injection in fractured-vuggy reservoirs significantly affects the displacement efficiency. However, there is a lack of in-depth understanding of the stability of the gas–water interface migration during water injection or gas injection in such reservoirs. In order to deal with this problem, this study combines indoor 3D visualization physical simulation experiment and fracture-cavity reservoir flow simulation. The law of interface transport and oil recovery in the process of injection of gas/water considering the degree of filling of fracture holes was studied and the influence of formation on crude oil viscosity, gas injection speed, inclination angle and other factors on the stability of the interface was compared. Results show that, under the influence of gravity differentiation, the oil–water interface of high-viscosity crude oil fluctuates obviously after water breakthrough, and the oil–water interface tends to be unstable, forming uneven oil cones. By reducing the gas drive speed, water invasion can be effectively inhibited to achieve a stable interface which accordingly improves the oil recovery. Full article

This study investigates the surrounding rock failure caused by the fracture line of the main roof above the gob-side roadway during fully mechanized top-coal caving mining in a 19 m thick coal seam. As mining progresses, stress concentration occurs in the roadway roof. Furthermore, the fracture line of the main roof above the roadway poses a significant threat to the structural stability of the gob-side roadway, leading to the localized failure of the roof structure, which consequently affects the safe and efficient production of the mine. This study investigates the shear failure mechanism of the roadway top coal and analyzes the failure characteristics and stress evolution law of the surrounding rock when the main roof fracture line (MRFL) is located above the roadway through three integrated approaches: theoretical analysis, numerical simulation, and physical similarity modeling. To effectively mitigate damage to the top coal, it is proposed to implement a five-hole tray coupled with high-strength prestressed anchor cables for reinforcing the surrounding rock, while compact wooden piles in combination with single pillars are employed to strengthen the roadway support control measures. It is verified by field tests that these control methods significantly improve the stability of coal above the entry and greatly mitigate the likelihood of surrounding rock failure. Full article