Physics design point of high-field stellarator reactors

The ongoing development of electromagnets based on High Temperature Superconductors has led to the conceptual exploration of high-magnetic-field fusion reactors of the tokamak type, operating at on-axis fields above 10 T. In this work we explore the consequences of the potential future availability of high-field three-dimensional electromagnets on the physics design point of a stellarator reactor. We find that, when an increase in the magnetic field strength $B$ is used to maximally reduce the device linear size $R\sim B^{-4/3}$ (with otherwise fixed magnetic geometry), the physics design point is largely independent of the chosen field strength/device size. A similar degree of optimization is to be imposed on the magnetohydrodynamic, transport and fast ion confinement properties of the magnetic configuration of that family of reactor design points. Additionally, we show that the family shares an invariant operation map of fusion power output as a function of the auxiliary power and relative density variation. The effects of magnetic field over-engineering and the $R(B)$ scaling of design points with constant neutron wall loading are also inspected. In this study we use geometric parameters characteristic of the \emph{helias} reactor, but most results apply to other stellarator configurations.

The use of «native» wavelet transform for determining lateral density variation of the Volgo-Uralian subcraton

In the last two decades in conjunction with the development of satellite gravimetry, the techniques of regional-scale inverse and forward gravity modeling started to be more actively incorporated in the construction of crustal and lithospheric scale models. Such regional models are usually built as a set of layers and bodies with constant densities. This approach often leads to a certain difference between the initially used measured gravity field and a gravity field that is produced by the model. One of the examples of this kind of models is a recent lithospheric model of the Volgo-Uralian subcraton. In the current study, we are applying the method of «native» wavelet transform to the residual gravity anomaly for defining the possible lateral density variations within the lithospheric layers of Volgo-Uralia. Keywords: wavelet transform; gravity field inversion; forward gravity modeling; Volgo-Uralian subcraton; satellite gravimetry.

The carrier wave design for the synthesis of non-Gaussian and non-stationary signals using the amplitude modulation method

The methods of generating stationary random signals, both Gaussian and non-Gaussian, are quite complete, but the researches on the non-stationary signals are insufficient. Especially, the current methods seldom provide mathematical bases about the kurtoses of the produced signals such that the generations of non-stationary non-Gaussian signals with the desired kurtoses are inefficient, which also decrease the flexibility of the real-time control in shaker table tests. In the article, the amplitude modulation method is employed to realize the signal synthesis. The carrier waves of the method are investigated considering the bursts overlapping situations. At first, the explicit equations between the kurtoses of the synthesized signals and the three crucial parameters (the offset, the distance between a pair of adjacent bursts and the parameter of the Beta-distributed random variables) are deduced for the carrier waves with both overlapped bursts and non-overlapped busts. Meanwhile, to solve the power spectral density variation led by the amplitude modulation method, an explicit expression of a rescaling parameter is also proposed. Furthermore, the impacts of the three parameters are investigated; the focus of the investigation is on how the kurtoses of the synthesized signals are changed by the parameters. Based on the results of the investigation, a test procedure is put forward to apply the proposed equations in a shaker table test. The control process of the test demonstrates that the real-time kurtoses control can be achieved efficiently with the help of the newly proposed equations.

Characterisation of silicon oxynitride thin films and their response to swift heavy-ion irradiation

Silicon oxynitrides (a-SiOxNy) are materials whose composition ranges between two binary materials: a-SiO2 and a-Si3N4. In this work, we present a systematic study of the fine structure of the damaged regions produced by swift heavy-ions (SHIs), or ‘ion-tracks’ and quantify the density variation profiles with respect to composition. Thin films were deposited by plasma-enhanced chemical vapor deposition (CVD), where thickness, density, stoichiometry and bond configuration were initially determined. The fine structure and radial size of the ion tracks was determined using small angle X-ray scattering. The tracks exhibit a core-shell cylindrical geometry, with an under-dense core surrounded by an over-dense shell with a smooth transition between the two regions. We observed two trends with composition: a constant increasing ion track radius is observed when the O/Si ratio is below one (0≤x≤1). And saturation of the radial dimensions above this value, being similar to a-SiO2. The IR spectra allowed to quantify the bond configuration and its evolution with fluence. After irradiation, the energy deposited by the SHI irradiation leads to a preferential damage of Si-N bonds. IR spectroscopy also showed the formation of new Si-H bonds with increasing fluences and resulting in a rather complex ion-induced structural modification of the a-SiOxNy network.

Construction of mammographic findings simulators to study the interference of silicone implants in the diagnosis of breast cancer

Introduction: Breast cancer is the most prevalent malignant neoplasm among women, presenting itself, in 99% of cases, in females. Augmentation mammoplasty is the most performed aesthetic surgical intervention in the world. Objective: This study aims to improve the search for biomaterials compatible with mammographic findings suggestive of malignancy, to further study the interference of silicone implants in mammography exams. Methods: To make the simulators of mammographic findings, a bibliographic study of possible biomaterials that presented compatibility with the breast tissue and with possible neoplastic findings was carried out. The validation process of the simulators made in this work was carried out in two stages. Results: The result found was a density variation between 2.54 and 2.57 (dimensionless unit). For the second plate, the individual optical density of each material was analyzed. The results found for fiberglass ranged between 1.95 and 2.63. For chicken eggshells between 0.59 and 0.80. For the glycerin suppository, values between 1.43 and 2.29 were found. And for plastic PVC film 1.78 to 2.53. Conclusion: Given the above, it is observed that the first plate as a whole is compatible with mammographic studies. However, on the second plate, when the materials were analyzed separately, it was observed that fiberglass and plastic PVC film were the closest to compatibility with the commercial phantom, being compatible materials to simulate breast neoplasms in possible further studies.

Application of Tire Waste Material to Enhance the Properties of Saudi Class G Oil Well Cement

Cementing is an important operation for the integrity of the wellbore due to its role in providing several functions. To perform these functions, a high performance cement is required. Different types of additives and materials have been added to the cement slurry to improve its performance. Tire waste material is considered one of the greatest wastes globally. It is a dangerous material to the environment and human. Subsequently, it has been included in many industrial processes to reduce its hazards. This work evaluated the application of tire waste material in oil and gas industry to improve the properties of Saudi class G oil well cement. Two cement slurries were formulated under high pressure and high temperature of 3000 psi and 292 °F, respectively. The first slurry was the base cement without tire waste and the second slurry contained the tire waste. The effect of using the two slurries on the cement properties such as density variation, compressive strength plastic viscosity, Poisson's ratio and porosity was evaluated. The results showed that, when tire waste material was used, lower density variation was accomplished. Using tire waste was efficient to decrease the density variation to an extremely low proportion of 0.5%. Adding tire waste to the cement composition decreased its plastic viscosity by 53.1%. The tire waste cement sample had a higher Poisson's ratio than the base cement sample by 14.3%. Utilizing the tire waste improved the cement's compressive strength by 48.3%. The cement porosity was declined by 23.1% after adding the tire waste. Beside the property's enhancement in the cement, the application of tire waste has also an economical advantage, since it is inexpensive material which is influential in our daily life.

CHILES VERDES: Radio Variability at an Unprecedented Depth and Cadence in the COSMOS Field

Although it is well established that some extragalactic radio sources are time-variable, the properties of this radio variability, and its connection with host galaxy properties, remain to be explored—particularly for faint sources. Here we present an analysis of radio variable sources from the CHILES Variable and Explosive Radio Dynamic Evolution Survey (CHILES VERDES)—a partner project of the 1.4 GHz COSMOS H i Large Extragalactic Survey. CHILES VERDES provides an unprecedented combination of survey depth, duration, and cadence, with 960 hr of 1–2 GHz continuum VLA data obtained over 209 epochs between 2013 and 2019 in a 0.44 deg2 section of the well-studied extragalactic deep field, COSMOS. We identified 18 moderate-variability sources (showing 10%–30% flux density variation) and 40 lower-variability sources (2%–10% flux density variation). They are mainly active galactic nuclei (AGNs) with radio luminosities in the range of 1022–1027 W Hz−1, based on cross-matching with COSMOS multiwavelength catalogs. The moderate-variability sources span redshifts z = 0.22–1.56, have mostly flat radio spectra (α > −0.5), and vary on timescales ranging from days to years. The lower-variability sources have similar properties, but generally have higher radio luminosities than the moderate-variability sources, extending to z = 2.8, and have steeper radio spectra (α < −0.5). No star-forming galaxy showed statistically significant variability in our analysis. The observed variability likely originates from scintillation on short (∼week) timescales, and Doppler-boosted intrinsic AGN variability on long (month–year) timescales.

Evaluation of density variations to determine impact on sterile compounding

Purpose To determine the density variation between (1) the measured density and manually calculated density, (2) density variation of different lots, and (3) density variation of different drug manufacturers in order to support institutions using gravimetric compounding methods. Summary Seventeen sterile injectable ingredient (drug) vials frequently used to make compounded sterile products (CSPs) were identified based on the ability to ensure that for each drug there were vials produced by 2 different manufacturers and 2 lots produced by the same manufacturer. Each drug’s density was measured using a density meter and by manual calculation using the institution’s density formula. Density differences were compared between the 2 different methods. Overall, the average drug density difference between the measured versus calculated density was determined to be 0.022. Further analysis revealed the average difference between the different lot numbers of the same manufacturers was 0.005 for the nonhazardous drugs and 0.0001 for the hazardous drugs. The average difference between the different manufacturers of the same drug was determined to be 0.008 for the nonhazardous drugs and 0.001 for hazardous drugs. Conclusion No clinically meaningful difference exists when manually calculating a drug’s density compared to measuring a drug’s density using a density meter. In addition, there does not appear to be a sizeable density variation between the same drugs in separate lots or produced by different manufacturers.