Simuliranje i upravljačka strategija 5.6 kV 17-razniskog STATCOM sustava uz SVG uvjet

To achieve high-voltage reactive power compensation, a 5.6kV 17-level STATCOM under SVG Condition is presented. In this paper, we use a cascaded H-bridge multilevel star-connection converter whose system structure and circuit schematic are described. Then by using the phase-shifted carrier modulation strategy and the active-reactive current decoupling method, the STATCOM performs quite well. Moreover modulation strategy of the 17-level STATCOM based on the active disturbance rejection control (ADRC) is presented and the analytical formulas are described. For implementation, control strategy for DC bus voltage balance in cascaded H-bridge multilevel converters, time average distribution method and extreme value offset method are applied in our design. Finally, simulation results demonstrate that the proposed 17-level STATCOM is capable of reactive power compensation, simultaneous controlling and balancing the DC side voltages during the work and verify that high-voltage reactive power can be accurately and effectively compensated.Za postizanje kompenzacije jalove snage uz visoki napon, predstavljen je STATCOM s 5.6 kV i 17-razina uz SVG uvjet. U ovom radu koristimo kaskadni višerazinski H-mosni pretvarač u zvijezda spoju uz opisane strukturu i shemu spoja. Zatim korištenjem strategije modulacije s fazno-pomaknutim signalom nosioca i metode rasprezanja radno-jalove struje, STATCOM pokazuje prilično dobro vladanje. Uz to, prikazana je strategija modulacije 17-razinskog STATCOM-a zasnovana na upravljanju s aktivnim odbacivanjem smetnji (ADRC) te su opisane analitičke formule. Za implementaciju, u naš dizajn primjenjene su upravljačka strategija balansiranja napona DC sabirnice u kaskadnom višerazinskom H-mosnom pretvaraču te metoda vremenskog uprosječavanja razdiobe i metoda ekstremne vrijednosti pomaka. Konačno, simulacijski rezultati pokazuju da je predloženi 17-razinski STATCOM sposoban za kompenzaciju jalove snage, istovremeno upravljanje i balansiranje napona DC strane u radu te potvrđuju da je jalovu snagu uz visoki napon moguće točno i djelotvorno kompenzirati

Understanding the Impact of Indirect System Use in the hospital: A Control Perspective

In the hospital, designated system users (i.e., principal physicians) are usually found to delegate system-related tasks to other people (i.e., agent physicians). This behavior is termed as indirect use. Despite the prevalence of indirect use, the understanding of its clinical impacts is limited. In this research, we first propose different effects of indirect use on clinical care quality and physician–patient interaction care quality. We then draw on the agency theory and organization control literature to identify the moderating effects of three control mechanisms: input control, process control, and outcome control. A total of 242 physicians from a general public hospital were surveyed to verify the proposed hypotheses. The results show that three control mechanisms moderate the impacts of indirect use in different manners. Implications and plan for future research are then discussed

Should chronic hepatitis B mothers breastfeed? a meta analysis

<p>Abstract</p> <p>Background</p> <p>Hepatitis B virus (HBV) exists in the breast milk of chronic hepatitis B (CHB) mothers. The authors use a meta-analytic technique to quantify the evidence of an association between breastfeeding and risk of CHB infection among the infants vaccinated against HBV.</p> <p>Methods</p> <p>Literature search is performed up to 2010 on the relationship between infantile CHB infection within one-year follow up after immunization with the third-dose hepatitis B vaccine and breastfeeding. Two reviewers independently extract the data and evaluate the methodological quality. A random-effects model is employed to systematically combine the results of all included studies.</p> <p>Results</p> <p>Based on data from 32 studies, 4.32% (244/5650) of infants born of CHB mothers develop CHB infection. The difference in risk of the infection between breastfed and formula-fed infants (RD) is -0.8%, (95% confidence interval [CI]: -1.6%, 0.1%). Analysis of the data from 16 of the studies finds that RD for mothers who are positive for the HBeAg and/or the HBV DNA, 0.7% (95%CI: -2.0%, 3.5%), is similar to that for those who are negative for these infectivity markers, -0.5% (95%CI: -1.7%, 0.6%).</p> <p>Conclusions</p> <p>Breast milk is infectious; yet, breastfeeding, even by mothers with high infectivity, is not associated with demonstrable risk of infantile CHB infection, provided that the infants have been vaccinated against HBV at birth.</p

Isospin dependence of projectile-like fragment production at intermediate energies

The cross sections of fragments produced in 140 $A$ MeV $^{40,48}$Ca + $^9$Be and $^{58,64}$Ni + $^9$Be reactions are calculated by the statistical abration-ablation(SAA) model and compared to the experimental results measured at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University. The fragment isotopic and isotonic cross section distributions of $^{40}$Ca and $^{48}$Ca, $^{58}$Ni and $^{64}$Ni, $^{40}$Ca and $^{58}$Ni, and $^{48}$Ca and $^{64}$Ni are compared and the isospin dependence of the projectile fragmentation is studied. It is found that the isospin dependence decreases and disappears in the central collisions. The shapes of the fragment isotopic and isotonic cross section distributions are found to be very similar for symmetric projectile nuclei. The shapes of the fragment isotopic and isotonic distributions of different asymmetric projectiles produced in peripheral reactions are found very similar. The similarity of the distributions are related to the similar proton and neutron density distributions inside the nucleus in framework of the SAA model.Comment: 7 pages, 4 figures; to be published in Phys Rev

Molecular Mechanism of Z α1-Antitrypsin Deficiency.

The Z mutation (E342K) of α1-antitrypsin (α1-AT), carried by 4% of Northern Europeans, predisposes to early onset of emphysema due to decreased functional α1-AT in the lung and to liver cirrhosis due to accumulation of polymers in hepatocytes. However, it remains unclear why the Z mutation causes intracellular polymerization of nascent Z α1-AT and why 15% of the expressed Z α1-AT is secreted into circulation as functional, but polymerogenic, monomers. Here, we solve the crystal structure of the Z-monomer and have engineered replacements to assess the conformational role of residue Glu-342 in α1-AT. The results reveal that Z α1-AT has a labile strand 5 of the central β-sheet A (s5A) with a consequent equilibrium between a native inhibitory conformation, as in its crystal structure here, and an aberrant conformation with s5A only partially incorporated into the central β-sheet. This aberrant conformation, induced by the loss of interactions from the Glu-342 side chain, explains why Z α1-AT is prone to polymerization and readily binds to a 6-mer peptide, and it supports that annealing of s5A into the central β-sheet is a crucial step in the serpins' metastable conformational formation. The demonstration that the aberrant conformation can be rectified through stabilization of the labile s5A by binding of a small molecule opens a potential therapeutic approach for Z α1-AT deficiency

Comprehensive investigation of Quantum Oscillations in Semimetal Using an ac Composite Magnetoelectric Technique with Ultrahigh Sensitivity

Quantum oscillation (QO), a physical phenomenon that reflects the characteristics of the Fermi surface and transport fermions, has been extensively observed in metals and semimetals through various approaches, like magnetostriction, magnetization, resistivity, and thermoelectric power. However, only some allowed oscillation frequencies can be revealed by each individual method, particularly in semimetals with intricate Fermi pockets and associated magnetic breakdown phenomena. In this paper, we present the application of an ac composite magnetoelectric (ME) technique to measure the QOs of a topological nodal-line semimetal, ZrSiS, which possesses six fundamental QO frequencies. By employing the ME technique with a maximum magnetic field of 13 T and a minimum temperature of 2 K, we are able to capture all the fundamental frequencies and most of the permissible magnetic breakdown frequencies. In comparison, some of the frequencies were missing in the aforementioned four methods under identical measurement conditions. Remarkably, a series of magnetic breakdown frequencies around 8000 T were revealed even in a magnetic field as low as 7.5 T. These findings highlight the ME technique as an ultrahigh-sensitive tool for studying Dirac Fermions and other topological semimetals with complex Fermi surfaces.Comment: 22 pages, 4 figure

Molecular imaging research in atherosclerosis: A 23-year scientometric and visual analysis

Background: Cardiovascular and cerebrovascular diseases are major global health problems, and the main cause is atherosclerosis. Recently, molecular imaging has been widely employed in the diagnosis and therapeutic applications of a variety of diseases, including atherosclerosis. Substantive facts have announced that molecular imaging has broad prospects in the early diagnosis and targeted treatment of atherosclerosis.Objective: We conducted a scientometric analysis of the scientific publications over the past 23 years on molecular imaging research in atherosclerosis, so as to identify the key progress, hotspots, and emerging trends.Methods: Original research and reviews regarding molecular imaging in atherosclerosis were retrieved from the Web of Science Core Collection database. Microsoft Excel 2021 was used to analyze the main findings. CiteSpace, VOSviewer, and a scientometric online platform were used to perform visualization analysis of the co-citation of journals and references, co-occurrence of keywords, and collaboration between countries/regions, institutions, and authors.Results: A total of 1755 publications were finally included, which were published by 795 authors in 443 institutions from 59 countries/regions. The United States was the top country in terms of the number and centrality of publications in this domain, with 810 papers and a centrality of 0.38, and Harvard University published the largest number of articles (182). Fayad, ZA was the most productive author, with 73 papers, while LIBBY P had the most co-citations (493). CIRCULATION was the top co-cited journal with a frequency of 1,411, followed by ARTERIOSCL THROM VAS (1,128). The co-citation references analysis identified eight clusters with a well-structured network (Q = 0.6439) and highly convincing clustering (S = 0.8865). All the studies calculated by keyword co-occurrence were divided into five clusters: “nanoparticle,” “magnetic resonance imaging,” “inflammation,” “positron emission tomography,” and “ultrasonography”. Hot topics mainly focused on cardiovascular disease, contrast media, macrophage, vulnerable plaque, and microbubbles. Sodium fluoride ⁃PET, targeted drug delivery, OCT, photoacoustic imaging, ROS, and oxidative stress were identified as the potential trends.Conclusion: Molecular imaging research in atherosclerosis has attracted extensive attention in academia, while the challenges of clinical transformation faced in this field have been described in this review. The findings of the present research can inform funding agencies and researchers toward future directions

Advantages of GaN Based Light-Emitting Diodes with a P-InGaN Hole Reservoir Layer

A p-type InGaN hole reservoir layer (HRL) was designed and incorporated in GaN based light-emitting diodes (LEDs) to enhance hole injection efficiency and alleviate efficiency droop. The fabricated LEDs with p-type HRL exhibited higher light output power, smaller emission energy shift and broadening as compared to its counterpart. Based on electrical and optical characteristics analysis and numerical simulation, these improvements are mainly attributed to the alleviated band bending in the last couple of quantum well and electron blocking layer, and thus better hole injection efficiency. Meanwhile, the efficiency droop can be effectively mitigated when the p-InGaN HRL was used