Research on the Physical Characteristics of Hot-Pressed Sintering Preparing Self-Fluxing Filler by X-Ray Diffraction

In this paper, Al-12Si self-fluxing filler metal ring was prepared with Al-12Si alloying powders and KAlF4 flux by hot pressed sintering (HPS) method. The microstructure and mechanical properties of the brazing alloy and the brazed 3003 aluminum alloy joint were investigated. The results showed that Al-12Si self-fluxing filler metal ring could be successfully obtained by HPS at 470°C using a pressure of 300MPa. The prepared filler metal ring was dense and defect-free and the microstructure was mainly composed of Si phase with KAlF4 flux grain uniformly distributed in the Al matrix. The 3003 aluminum alloy joint interface brazed by the prepared filler metal was also well bonded and no pore and defect was found. A quite high joint strength of 75MPa was obtained which is equal to the strength of joint brazed using commercial Al-Si self-fluxing wires prepared by hot extrude method. The results revealed that the filler metal rings fabricated by HPS process had great potentiality in brazing of aluminum alloy especially for the Al-Al pipes joining due to its high joint strength, low cost and the convenience for industrial application.

A Monumental Horse Burial in the Armenian Highlands

Here we report on the unprecedented discovery of the complete skeleton of a ritually interred adult stallion with a bronze ring in its mouth. The horse was buried in a unique 15-meters diameter monumental stone-built tomb excavated in the Aghavnatun necropolis located on the southern slopes of Mt. Aragats, in the northern fringes of the Ararat Depression, Republic of Armenia. The tumulus was roughly circular; the horse’s remains were found in situ, in an inner oval-shaped structure. Our methodological procedure included a detailed description of the burial, a taphonomic study of the bones, and meticulous morphometric observations and measurements, and thus we could provide a taxonomic defi nition and an age estimate. Direct radiometric dating of the horse’s skeleton provided a date of 2130±20 BP. The morphological characteristics of the horse, with its tall stature and slender feet, suggest that it was a large individual, similar to the extinct breed of Nisean horse previously known mainly from textual and iconographical sources. The metal ring found in the mouth of the horse suggests that it likely served as a breeding stallion. This discovery presents a unique combination of zooarchaeological evidence for the importance of the horse in the Parthian-Hellenistic worlds, and advances our understanding of the broad social signifi cance of the past breeding of equids in the Armenian Highlands.

Результаты работ на грунтовом могильнике Максимовка I в лесостепном Поволжье в 2018 г.

Introduction. This is a report on the results of archaeological excavations at Maksimovka I, the subterranean burial ground located in the forest-steppe Volga region. The site is unique because it contains burial complexes of different epochs. The purpose of the paper is to introduce the materials found during the 2018 excavations for the attention of the academic community. In particular, the paper focuses on the description and characterization of the archaeological complexes under investigation, and, also, on their cultural-chronological attribution. Data. The cultural layer was not particularly rich but contained fragments of Neolithic, Eneolithic, and Bronze Age ceramics, stone tools, and waste left after stone processing. Three burials were examined in the excavation area. The first burial comprised the skeleton of a deceased person in a supine position; the head oriented to the north-northeast; the grave goods included iron items (a fragment of a boiler and of a bit, rod-shaped items, and a firesteel), grindstones, and flints. The second buried person was found in the seated position, leg bones bent at the knee joint, head oriented to northeast; the finds included a nonferrous metal ring, a bone pendant, a silicon wafer, and tubular beads. The third buried person was also in a seated position, head oriented to the northeast; no grave goods were found in the third burial. Also, two other burial constructions recovered on the site were partially examined. Results. The first burial was attributed to the Golden Horde period in the Middle Ages (the second half of the 13th or the 14th c.). The second burial has a number of parallels to burial complexes of mid-late Eneolithic era of the forest-steppe Volga region. The third burial was left unidentified in terms of its cultural-chronological attribution, granted the non-standard position of the skeletal remains in the grave and the absence of goods. Conclusions. The examination of the subterranean burial ground Maksimovka I has allowed to introduce the archaeological material of different periods, such as Neolithic, Eneolithic, Bronze, and Middle Ages.

Strangulation of the penis with a metal ring. Clinical case

Penile trauma is the most complex, diverse and hard to rehabilitate injury. The reasons are anatomical structure and localization of the organ and its multifunctionality. Penile strangulation is the most common and typical type of genital injury; incidence is 1 case per 5,000 males. However, urologists in their practice rarely encounter penile strangulation with a metal ring. Some objects, metallic or other, can be placed on the penis to increase sexual activity. We describe a clinical case of a 70-year-old patient who sought medical care at the emergency room due to penile strangulation by a metal ring (a nut). The patient sought assistance 3 days after putting the metal ring on his penis by himself.

A metasurface-enabled Fabry–Pérot (FP) circularly polarized antenna with continuous wideband polarization conversion purity

In this paper, a wideband continuous pure right hand circularly polarized (RHCP), high gain, and low-radar cross-section (RCS) array antenna is proposed. A linear-to-circularly polarization conversion (LCPC) Metasurface (MS) is employed as the superstrate of the Fabry–Pérot (FP) resonator antenna, consisting of two oblique slits etched patches located at top and bottom, respectively, and a metal ring with corner-cutting patch inside, that ensure a wideband transmission and reflection LCPC frequencies ranging from 9 to 22 GHz, and 7–13.5 GHz, respectively. While, a pure RHCP LCPC frequency band of 9–12 GHz is produced by adopt the proposed MS that is benefit from the design of etched oblique slits and corner-cutting patch surrounded by the metal ring, where the magnitude and phase difference can be kept in the variation of ±3 dB and 10°, respectively. Then, a rectangle patch-fed MS FP antenna is designed by an arrangement of 5 × 5 MS unit cells. Following this, the sequence rotated technique is utilized to arrange the array antenna by 2 × 2 units, ensuring a wide band RCS frequency band. The proposed array antenna is fabricated and measured, which indicated the correctness of this design for performance of high gain, low RCS, and wideband pure RHCP. Compared with recent reported MS-based FP works, a wideband LCPC frequencies purity is obtained, and a good radiation and scattering performance is obtained in the design.

NUMERICAL AND ANALYTICAL MODELING OF STRESS-DEFORMED STATE OF THE METAL RING SEAL OF THE TUBING HAGER

The article presents a numerical and analytical modeling of the stress-strain state of a metal ring seal of a tubing hanger under installation loads, as well as under the influence of well pressure. An analytical method for calculating strength and tightness within the elastic formulation is proposed. The calculation by the finite element method was carried out in order to take into account plastic deformations, which make it possible to study the influence of the geometry of the contact zone of the sealing ring on the width of the contact pad and the magnitude of the contact pressure. Comparison of the calculation results by the analytical method and the finite element method is carried out. It is shown that the analytical method, as less labor-intensive, can be used at the initial stages of designing this type of equipment.

A Potential Plasmonic Biosensor Based Asymmetric Metal Ring Cavity with Extremely Narrow Linewidth and High Sensitivity

To achieve high sensitivity and multi-mode sensing characteristics based on the plasmon effect, we explored a high-sensitivity refractive index sensor structure with narrow linewidth and high absorption characteristics based on theoretical analysis. The sensor structure is composed of periodic asymmetric ring cavity array, spacer layer and metal thin-film layer. The reflection spectrum of this structure shows six resonance modes in the wavelength range from visible to near-infrared. The sensor performance was optimized based on the change of the sensor structure parameters combining the simulation data, and the results shown that this kind of asymmetric laminated structure sensor has good sensing performance. In theory, it can be combined with microfluidic technology to achieve sensing detection of diverse test samples, multi-mode and multi-component, which has great potential in the field of biosensing.

Numerical Investigations on the Shape Optimization of Stainless-Steel Ring Joint with Machine Learning

Since pipes used for water pipes are thin and difficult to fasten using welding or screws, they are fastened by a crimping joint method using a metal ring and a rubber ring. In the conventional crimping joint method, the metal ring and the rubber ring are arranged side by side. However, if water leaks from the rubber ring, there is a problem that the adjacent metal ring is rapidly corroded. In this study, to delay and minimize the corrosion of connected water pipes, we propose a spaced crimping joint method in which metal rings and rubber rings are separated at appropriate intervals. This not only improves the contact performance between the connected water pipes but also minimizes the load applied to the crimping jig during crimping to prevent damage to the jig. For this, finite element analyses were performed for the crimp tool and process analysis, and the design parameters were set as the curling length at the top of the joint, the distance between the metal rings and rubber rings, and the crimp jig radius. Through FEA of 100 cases, data to be trained in machine learning were acquired. After that, training data were trained on a machine learning model and compared with a regression model to verify the model’s performance. If the number of training data is small, the two methods are similar. However, the greater the number of training data, the higher the accuracy predicted by the machine learning model. Finally, the spaced crimping joint to which the derived optimal shape was applied was manufactured, and the maximum pressure and pressure distribution applied during compression were obtained using a pressure film. This is almost similar to the value obtained by finite element analysis under the same conditions, and through this, the validity of the approach proposed in this study was verified.

IMPACT OF CORONA DISCHARGE ON ASPERGILLUS NIGER SPORES AND CYATHUS OLLA MYCELIUM GROWTH

The article presents an investigation of the influence of the corona discharge with needle-ring electrode configuration on the efficiency of Aspergillus niger spore germination and Cyathus olla mycelium development. Current-voltage characteristics were measured for different distances between the needle and the metal ring. The plot of the dependence of conductance on voltage was built and the corona discharge breakthrough voltage was determined to be (2.7±0.1) kV. The treatment of Aspergillus niger spores was conducted at different development stages: at the germination stage (corona discharge treatment 1 day after the seeding) and dormant state (corona discharge treatment on the day of seeding). The growth rate of Cyathus olla mycelium in samples treated by corona discharge and in control group samples was investigated. The influence of the corona discharge on the potato dextrose agar growth medium before the seeding of Cyathus olla was studied. The pure cultures were obtained from the Culture Collection of Fungi at Kyiv University (FCKU) at the «Institute of Biology and Medicine» Educational and Scientific Centre of the Taras Shevchenko National University of Kyiv.