Fuzzy logic system for frequency stability analysis of wind farm integrated power systems

U radu se uvodi sustav fuzzy logike u analizi frekvencijskog odziva vjetroelektrana sastavljenih od generatora s turbinama na vjetar promjenljive brzine - variable speed wind turbine generators (WTGs). WTGs mogu pružiti frekvencijsku podršku koristeći svoje zalihe energije. Međutim, frekvencijski odziv pojedinačnog WTG razlikuje se od odziva drugih WTGs zbog njihovih različitih brzina vjetra. Istražuje se i koristi model frekvencijskog odziva utemeljen na protoku opterećenja istosmjerne struje kako bi se poboljšale funkcije članice sustava logike. Kad se pojave smetnje na mreži, sustav fuzzy logike može odrediti frekvencijski odziv vjetroelektrane prema ulaznim varijablama realnog vremena. Rezultati simulacije pokazuju da je projektirani sustav učinkovit i može doprinijeti analizi frekvencijske stabilnosti.This paper introduces a fuzzy logic system to analyse the frequency response of wind farms composed of variable speed wind turbine generators (WTGs). WTGs can provide frequency support by using their energy reserves. However, the frequency response of an individual WTG is different from that of other WTGs because of their respective actual wind speeds. The frequency response model based on the direct-current load flow is investigated and used to amend the membership functions of the logic system. When a network disturbance occurs, the fuzzy logic system can determine the frequency response of the wind farm according to real-time input variables. The simulation results indicate that the designed system is effective and can contribute to frequency stability analysis

Experimental study on fracture plugging effect of irregular-shaped lost circulation materials

Using micro-visualization experimental device for the formation of fracture plugging zone, the plugging behavior of irregular-shaped lost circulation materials (LCMs) with different types and concentrations in fractures was experimentally analyzed. The results show that the sealing time decreases significantly with the increase of material concentration. When the concentration is 20%, the sealing times of materials LCM-1∼LCM-5 are 6s, 7s, 5s, 6s, 4s, respectively. The formation of fracture plugging zone includes two stages, and the main factors affecting the formation of fracture plugging zone are flatness, roundness, convexity and concentrations. Flatness affects the retention stage of LCMs through the matching degree between particle size and fracture width. Convexity and roundness affect the retention stage by increasing the friction coefficient between particles. The high-efficiency retention ability of irregular LCMs is characterized by strong matching to fracture width, and strong friction and sliding resistance between particles. It is recommended that the optimized geometric parameters of high-efficiency retention materials should meet the requirements of “low flatness, low roundness and low convexity” (flatness \u3c0.6, roundness \u3c0.6 and convexity \u3c0.8), which can improve the plugging effect significantly

Effect and complications of different surgical methods in treatment of laryngeal carcinoma

Objective·To compare the effects and complications of carbon dioxide laser laryngectomy and open partial laryngectomy in the treatment of laryngeal carcinoma.Methods·Clinical data of 101 patients with stage Ⅰ-Ⅲ laryngeal squamous cell carcinoma admitted to Renji Hospital, Shanghai Jiao Tong University School of Medicine from January 2013 to January 2018 were selected and divided into open surgery group and minimally invasive group according to different surgical methods. The open surgery group received open partial laryngectomy (57 cases), and the minimally invasive group received carbon dioxide laser laryngectomy (44 cases). Follow-up visits were made by telephone and outpatient visits, and the operation time, postoperative laryngeal mucosa edema time, length of stay, 5-year survival rate, complication rate and recurrence rate of the two groups were compared in the different clinical stages (stage Ⅰ, stage Ⅱ, and stage Ⅲ) and tumor locations (glottic type and non-glottic type).Results·The operation time, postoperative laryngeal mucosa edema time and length of stay of the minimally invasive group were shorter than those of the open surgery group (P<0.05). Comparison of the 5-year survival rates of patients with the same clinical stage and glottic type between the two groups showed no statistically significant difference (both P>0.05); while comparison of the 5-year survival rates of patients with non-glottic type between the two groups (62.5% in the open surgery group vs 0 in the minimally invasive group) showed a statistically significant difference (P<0.05). In the minimally invasive group, there were 3 cases of complications, including 1 case of fever and 2 cases of lung infection; in the open surgery group, there were 14 cases of complications, including 5 cases of fever, 7 cases of lung infection and 2 cases of pharyngeal fistula. The complication rate of patients in the minimally invasive group (6.82%, 3/44) was lower than that in the open surgery group (24.60%, 14/57), and the difference was statistically significant (P<0.05); the complication rate of patients with stage Ⅱ and glottic type in the minimally invasive group was significantly lower than that in the open surgery group (P<0.05). Comparing the recurrence rate of patients in the two groups (10.53% in the open surgery group vs 2.27% in the minimally invasive group), the difference was not statistically significant (P>0.05).Conclusion·Compared with open partial laryngectomy, carbon dioxide laser laryngectomy has faster postoperative recovery and lower complication rate in the treatment of early and middle laryngeal malignant tumors, so it is worth promoting

Controlling mass and energy diffusion with metamaterials

Diffusion driven by temperature or concentration gradients is a fundamental mechanism of energy and mass transport, which inherently differs from wave propagation in both physical foundations and application prospects. Compared with conventional schemes, metamaterials provide an unprecedented potential for governing diffusion processes, based on emerging theories like the transformation and the scattering cancellation theory, which enormously expanded the original concepts and suggest innovative metamaterial-based devices. We hereby use the term ``diffusionics'' to generalize these remarkable achievements in various energy (e.g., heat) and mass (e.g., particles and plasmas) diffusion systems. For clarity, we categorize the numerous studies appeared during the last decade by diffusion field (i.e., heat, particles, and plasmas) and discuss them from three different perspectives: the theoretical perspective, to detail how the transformation principle is applied to each diffusion field; the application perspective, to introduce various intriguing metamaterial-based devices, such as cloaks and radiative coolers; and the physics perspective, to connect with concepts of recent concern, such as non-Hermitian topology, nonreciprocal transport, and spatiotemporal modulation. We also discuss the possibility of controlling diffusion processes beyond metamaterials. Finally, we point out several future directions for diffusion metamaterial research, including the integration with artificial intelligence and topology concepts.Comment: This review article has been accepted for publication in Rev. Mod. Phy

Utilization of glucagon-like peptide-1 receptor agonists in children and adolescents in China: a real-world study

BackgroundGlucagon-like peptide-1 receptor agonists (GLP-1RAs) have been widely used in treating type 2 diabetes mellitus (T2DM) and obesity in adults, but scientific research about the indication in children and adolescents is scarce. The current study aims to explore the prescriptions of GLP-1RAs in children and adolescents in China and to evaluate its rationality.MethodsGLP-1RA prescriptions of children and adolescents were retrospectively obtained from the Hospital Prescription Analysis Cooperative Project. The study extracted information on patient’s demographic characteristics, monotherapy and combination therapy of GLP-1RAs, and trends in GLP-1RA usage from 2016 to 2021. The rationality of GLP-1RA prescriptions was comprehensively assessed based on the indications approved by China National Medical Products Administration (NMPA), the U.S. Food and Drug Administration (FDA), European Medicines Agency (EMA), Pharmaceuticals and Medical Devices Agency (PMDA), and published randomized controlled trials (RCTs).ResultsA total of 234 prescriptions from 46 hospitals were included, with a median age of 17 years old. The majority of patients were diagnosed with overweight/obesity or prediabetes/diabetes, accounting for 43.59% and 46.15%, respectively. There were 88 patients on GLP-1RA monotherapy. GLP-1RAs plus metformin was the most common combination therapy (38.89%). 12.39% of patients were found a co-administration with orlistat. The share of overweight/obesity prescriptions increased from 27% in 2016 to 54% in 2021, whereas prediabetes/diabetes prescriptions declined from 55% to 42%. The prescriptions were divided into appropriate and questionable groups according to the diagnosis, and the potentially questionable prescription was related to age (p = 0.017), department visited (p = 0.002), and any hospitalization (p &lt; 0.001).ConclusionsThis study described the prescribing of GLP-1RAs in children and adolescents. Our findings indicated that the utilization of GLP-1RAs has increased from 2016 to 2021. There was a strong basis for administering GLP-1RAs in overweight/obesity and prediabetes/diabetes, whereas the evidence was insufficient in other conditions. It is crucial to demand robust and sustained efforts to enhance the awareness of the safety of utilization of GLP-1RAs in children and adolescents

Periplasmic biomineralization for semi-artificial photosynthesis

Semiconductor-based biointerfaces are typically established either on the surface of the plasma membrane or within the cytoplasm. In Gram-negative bacteria, the periplasmic space, characterized by its confinement and the presence of numerous enzymes and peptidoglycans, offers additional opportunities for biomineralization, allowing for nongenetic modulation interfaces. We demonstrate semiconductor nanocluster precipitation containing single- and multiple-metal elements within the periplasm, as observed through various electron- and x-ray-based imaging techniques. The periplasmic semiconductors are metastable and display defect-dominant fluorescent properties. Unexpectedly, the defect-rich (i.e., the low-grade) semiconductor nanoclusters produced in situ can still increase adenosine triphosphate levels and malate production when coupled with photosensitization. We expand the sustainability levels of the biohybrid system to include reducing heavy metals at the primary level, building living bioreactors at the secondary level, and creating semi-artificial photosynthesis at the tertiary level. The biomineralization-enabled periplasmic biohybrids have the potential to serve as defect-tolerant platforms for diverse sustainable applications

C-18-Functionalized Magnetic Silica Nanoparticles for Solid Phase Extraction of Microcystin-LR in Reservoir Water Samples Followed by HPLC-DAD Determination

In this study, C-18-functionalized magnetic silica nanoparticle (Fe3O4@SiO2@C-18 MNPs) based magnetic solid phase extraction (MSPE) was successfully developed for the determination of microcystin-LR (MC-LR) in reservoir water samples followed by high performance liquid chromatography-diode array detection (HPLC-DAD). After the extraction, the adsorbent can be conveniently and rapidly separated from aqueous samples by an external magnet. The main factors influencing the extraction efficiency including the amount of the MNPs, the extraction time, the pH of sample solution, and desorption conditions were optimized to obtain high recoveries and extraction efficiency. High enrichment factor 500 was attained. Under the optimized experimental conditions, the calibration curve of MC-LR was linear in the range of 0.1-10.0 mu g/L with correlation coefficients (r(2)) 0.9996. Limit of detection (LOD, S/N=3) of the method was 0.056 mu g/L. The developed method was successfully applied to the determination of MC-LR in reservoir water samples. The method recoveries were obtained ranging from 73.3-104% for three spiked concentrations, with the relative standard deviations (RSD) of 2.90-4.30%. The developed Fe3O4@SiO2@C-18 MNPs-based MSPE coupled with HPLC-DAD demonstrated excellent sensitivity and repeatability, simplicity, rapidity, and ease of operation, as well as practical applicability