Design and analysis of a segmented blade for a 50 MW wind turbine rotor

Extreme-size wind turbines face logistical challenges due to their sheer size. A solution, segmentation, is examined for an extreme-scale 50 MW wind turbine with 250 m blades using a systematic approach. Segmentation poses challenges regarding minimizing joint mass, transferring loads between segments and logistics. We investigate the feasibility of segmenting a 250 m blade by developing design methods and analyzing the impact of segmentation on the blade mass and blade frequencies. This investigation considers various variables such as joint types (bolted and bonded), adhesive materials, joint locations, number of joints and taper ratios (ply dropping). Segmentation increases blade mass by 4.1%–62% with bolted joints and by 0.4%–3.6% with bonded joints for taper ratios up to 1:10. Cases with large mass growth significantly reduce blade frequencies potentially challenging the control design. We show that segmentation of an extreme-scale blade is possible but mass reduction is necessary to improve its feasibility.

Observation of a gravitational Aharonov-Bohm effect

Gravitational interference The Aharonov-Bohm effect is a quantum mechanical effect in which a magnetic field affects the phase of an electron wave as it propagates along a wire. Atom interferometry exploits the wave characteristic of atoms to measure tiny differences in phase as they take different paths through the arms of an interferometer. Overstreet et al . split a cloud of cold rubidium atoms into two atomic wave packets about 25 centimeters apart and subjected one of the wave packets to gravitational interaction with a large mass (see the Perspective by Roura). The authors state that the observed phase shift is consistent with a gravitational Aharonov-Bohm effect. —ISO

Applying Human-Centered Design Principles to Digital Syndromic Surveillance at a Mass Gathering in India: Viewpoint

In the wake of the COVID-19 pandemic, digital health tools have been deployed by governments around the world to advance clinical and population health objectives. Few interventions have been successful or have achieved sustainability or scale. In India, government agencies are proposing sweeping changes to India’s digital health architecture. Underpinning these initiatives is the assumption that mobile health solutions will find near universal acceptance and uptake, though the observed reticence of clinicians to use electronic health records suggests otherwise. In this practice article, we describe our experience with implementing a digital surveillance tool at a large mass gathering, attended by nearly 30 million people. Deployed with limited resources and in a dynamic chaotic setting, the adherence to human-centered design principles resulted in near universal adoption and high end-user satisfaction. Through this use case, we share generalizable lessons in the importance of contextual relevance, stakeholder participation, customizability, and rapid iteration, while designing digital health tools for individuals or populations.

WSOC and Its Relationship with BC, Levoglucosan and Transition Metals in the PM2.5 of an Urban Area in the Amazon

Water-soluble organic carbon (WSOC) makes up a large mass fraction of the organic carbon in the aerosol and can influence important cloud processes in the atmosphere. The capacity of WSOC to form metallic complexes with transition metals is well known; however, its influence on the aerosol of urban areas in the Amazon region is not very well known. In this study, we investigated the relationship between WSOC, black carbon (BC), levoglucosan (LEV) and transition metals (Fe, Cu and Mn) present in the PM2.5 (particles with a diameter smaller than 2.5 µm) of an urban environment during the dry season in the central Amazon. Oxalic acid (C2) was used to identify the influence of transition metals on WSOC. The mean mass concentration value of the PM2.5 was 14.72 μg m-3 (2.11-31.68 μg m-3). The WSOC made up 58.34% of the PM2.5 mass, followed by BC (20.28%), and LEV (2.62%). The WSOC showed significant correlation with the transition metals analyzed (> 0.56), especially Mn with C2 (linear coefficient (R2 ) = 0.74). A multiple linear regression with WSOC, BC and LEV showed a strong linear correlation between them (R2 = 0.86), indicating the influence of biomass burning and vehicle traffic on the organic aerosol.

Exploring Reggeon bound states in strongly-coupled $$ \mathcal{N} $$ = 4 super Yang-Mills

The multi-Regge limit of scattering amplitudes in strongly-coupled $$ \mathcal{N} $$ N = 4 super Yang-Mills is described by the large mass limit of a set of thermodynamic Bethe ansatz (TBA) equations. A non-trivial remainder function arises in this setup in certain kinematical regions due to excitations of the TBA equations which appear during the analytic continuation into these kinematical regions. So far, these analytic continuations were carried out on a case-by-case basis for the six- and seven-gluon remainder function. In this note, we show that the set of possible excitations appearing in any analytic continuation in the multi-Regge limit for any number of particles is rather constrained. In particular, we show that the BFKL eigenvalue of any possible Reggeon bound state is a multiple of the two-Reggeon BFKL eigenvalue appearing in the six-gluon case.

Dilaton chiral perturbation theory and applications

We review dilaton chiral perturbation theory (dChPT), the effective low-energy theory for the light sector of near-conformal, confining theories. dChPT provides a systematic expansion in both the fermion mass and the distance to the conformal window. It accounts for the pions and the light scalar, the approximate Nambu–Goldstone bosons for chiral and scale symmetry, respectively. A unique feature of dChPT is the existence of a large-mass regime in which the theory exhibits approximate hyperscaling, while the expansion nevertheless remains systematic. We discuss applications to lattice data, presenting successes as well as directions for future work.

MONEY CIRCULATION OF OLBIA PONTIUS AT THE FINAL STAGE OF CITY’S HISTORY

The aim of the study is to explain the unusually high for provincial city percentage of Roman denarii among the coins of ancient Olbia. Research methodology – principles of science, historicism, objectivity, generalization, historical-genetic and historical-typological. Scientific novelty. Some researchers of Olbia connected the final stage of its history with presence of barbarians, carriers of the Chernyakhiv culture (the second third of 3rd – the beginning of 5th c., the dominant population – the Goths). Other researchers believed that the material culture of the city retains its ancient character to the end. Modern analysis of finds from the late Roman layers of Olbia and its surroundings demonstrates undeniable Chernyakhiv analogies and shows the inclusion of the city in political and economic system of barbarians. The truth of this statement can be verified by comparing the numismatic materials of Chernyakhiv culture and Olbia of Roman times. In the area of this culture within the borders of former USSR, finds of more than 26 thousand Roman coins have been recorded. Coins modern to this culture (3rd – 4th c.) are a minority, and 78,7% are represented by earlier silver denarii of the 1st – 2nd c. The barbarians received these denarii from Rome as military contributions and subsidies or wage to military units. Some coins were put into circulation for internal payments. P. Karyshkovsky made statistical calculations of coins of the 1st – 4th c. from Olbia and found some local peculiarity. Unlike other ancient cities of Northern and Western Black Sea coast, among the Roman and provincial coins found in Olbia, the majority are denarii of the 1st – 2nd c.: 53,5% of finds. However, in Histria city (Western Black Sea Coast) denarii make only 17,3%. The peculiarity of Olbia collection can be explained by the history of this city. After the Gothic conquest (between the late 250s and early 270s), Olbia was reborn as small fortified town, a trade and craft center inhabited by Goth barbarians. The distribution of coin finds from the second half of 3rd to the beginning of 5th c. corresponds to the situation in Chernyakhiv culture. Issues of coins of that time came to its population in small quantities. However, the barbarians owned a large mass of old denarii of 1st – 2nd c. Some of them fall into the cultural layer of Olbia, which creates a false picture of money circulation of the city in early Roman times. The percentage of such denarii in Olbia without the participation of the later “Chernyakhiv” addition should be close to the percentage of denarii in Histria (17,3%). Conclusions. A feature of the money circulation of Olbia in Roman times is relatively large number of finds of denarii of the 1st – 2nd c. This can be explained by the fact that in the third quarter of 3rd c. the city was included into political and economic system of Chernyakhiv culture, where the main currency was the silver denarii of the 1st – 2nd c., which by that time were out of circulation in the Empire. The Olbia collection of Roman coins should be divided into the “Ancient” and “Chernyakhiv” (or “Late Antique”) periods, and the latter, in addition to coins of the second half of 3rd – 4th c., contains most of the denarii of the 1st – 2nd c.

Numerical investigation on adsorbent particle erosion characteristic of Y-shaped pipeline in S Zorb regeneration system with different influencing parameters

As the transportation pipeline of adsorbent in S Zorb regeneration system, due to large mass flow rate of particle and gas, it is often seriously worn, and even perforated, resulting in the leakage of adsorbent. It brings great inconvenience to the transportation of regenerated adsorbent and threats its long-term operation. Therefore, it is essential to study the erosion characteristic of Y-shaped adsorbent transportation pipe. It was studied by computational fluid dynamics (CFD) numerical simulation and the calculation results were validated by actual erosion profile. The results show that the high velocity of nitrogen and the high weight-fraction adsorbent particles accumulation is the key factor leading to severe erosion. It is also found that the small angle cutting is the erosion form. The effects of the intersection angle between the transportation pipe and feed pipe and the gas inlet velocity on the particle motion and erosion characteristics turn out to be significant. The research on the wear characteristics of adsorbent transportation pipeline can provide a certain reference for erosion prevention and optimization.

Acral perineurioma: a case report of a rare neoplasm successfully treated with autologous skin graft reconstructive surgery

Soft tissues perineurioma is a rare nerve sheath tumor that affects most of all the subcutaneous tissue. Even if it could present as a large mass, it is a benign neoplasm for whom a complete surgical excision represents the gold standard treatment. Considering that it usually affects acral sites of young people, can be challenging to perform a reconstructive surgery that allows a full functional recovery. We report the case of a woman in her 20s presenting a perineurioma of the sole of the foot, a nodule of about 2 cm of diameter that compromised the support of the foot on the ground. We performed a radical surgical excision with no recurrence after 3 years of follow up and we obtained a full functional recovery thanks to an autologous full-thickness skin graft.