Back Side Research Articles

Template-assisted electrodeposition of freestanding antimony, tin, and antimony-tin nanowire arrays from an ionic liquid

In the present study, we show the electrochemical synthesis of Sb, Sn, and Sb-Sn nanowire arrays from the ionic liquid 1-butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonate ([Py1,4]TfO) via templated-assisted approaches. Commercially available track etched polycarbonate template with a nominal pore diameter of 400 nm was utilized as a template. The nanowires were electrochemically deposited inside the pores of the template; then, a supporting copper layer was electrodeposited on the back side of the template. Subsequently, the template was dissolved with dichloromethane, and the structural morphology of the nanowire structures was explored by high-resolution scanning electron microscopy (SEM) and energy dispersive x-ray (EDX). Freestanding, mechanically stable nanowire arrays of Sb, Sn, and Sb-Sn with an average pore diameter of 400 nm were obtained. The charge/discharge characteristics of the electrodeposited nanowire films were investigated to explore the Li storage capacity of the fabricated electrodes. The results revealed that the electrodeposited nanowire films are promising anode candidates for the future generation of Li-ion batteries.Graphical abstract

Experimental study of dynamic pressure and wave load on variform vertical cylinders under extreme waves

Extreme waves pose a significant threat to the proliferating marine structures, however, the impact on the vertical cylinder with different cross-sectional shapes remains inadequately evaluated. Herein, we carried out a physical experiment, comprising 45 scenarios generated by three water depths, three wave paddle velocities, and five vertical cylinder models, to measure the extreme wave-induced pressure and load on this type of structure. The wave load and dynamic pressure distribution in time and spatial domains under the influence of cross-sectional shapes and wave conditions have been fully discussed. The experimental results indicate that: 1) As the position turns from front to back side, the circumferential pressure of five models initially decreases and then increases. 2) The maximum differential pressure between the front and back side decreases with increased water depth and decreased velocity, and occurs earlier than the peak pressure on the front side. 3) The chamfered cross-section (round and right triangle) can significantly reduce the wave load compared to the rectangular section, and the circular section suffers the lowest force logically. The dynamic pressure and wave load in this experiment can serve to establish a more sophisticated load model and provide valuable insights for marine structural design and disaster prevention.

Stable DC vacuum arc plasma generation from a 100 mm TiB2 cathode

Titanium diboride exhibits outstanding properties for hard and wear resistant coatings. However, efficient physical vapor deposition (PVD) processing through DC vacuum arc, with a deposition rate unreachable for any other PVD technique, is comparatively unexplored for TiB2 thin films due to challenges associated with the film synthesis process. In this work, we used an industrial scale arc plasma source having a plane cathode of 100 mm in diameter and a permanent magnet on its back side. We present analysis of the cathode surface, plasma generation/composition, as well as analysis of collected macroparticles. The cathode weight loss and the amount of generated macroparticles were measured as a function of process parameters (arc current and pressure, in both Ar and N2 gas). Plasma analysis shows average ion energies around 120 and 25 eV for Ti and B, respectively, and plasma ion composition of approximately 50 % Ti and 50 % B. The cathode weight loss was around 0.3–0.5 g/min, of which at least 25 % is estimated to be macroparticles. Notably, the intensity of the macroparticle generation was reduced with an increase in N2 pressure. Altogether, the results show a stable and reproducible plasma generation process and a high potential for the use of the cathodic arc as an efficient and useful method for deposition of metal borides.

Comprehensive Analysis of Xiaomi Mi 8 GNSS Antenna Performance.

The interest in precise point positioning techniques using smartphones increased with the launch of the world's first dual-frequency L1/L5 GNSS smartphone, Xiaomi Mi 8. The smartphone GNSS antenna is low-cost, sensitive to multipath, and limited by physical space and design. The main purpose of this work is to determine the mechanical location and antenna performance in terms of radiation pattern in an anechoic chamber using a Vector Network Analyzer (VNA) and robotic positioning platform by varying the elevation and azimuth angles between the transmitter and smartphone GNSS antennas; the power received and satellite visibility are developed in an outdoor scenario. The results show a Planar Inverted-F Antenna with an omnidirectional radiation pattern without gain. The L1/E1/B1 and L5/E5a/B2a GNSS antennas are physically located at the top face of the screen, with dimensions of 48 × 17 mm and 60 × 13 mm, respectively. With the screen with line-of-sight toward the sky, L5 satellites have a better signal-noise ratio (SNR), unlike the back side, which loses 99% of the data in the PPP solution. Under multipath scenarios, the L1 GNSS smartphone antenna works with 25% less power than the GPS user segment recommendation, showing high sensitivity to track weak signals.

Rethinking on the Anzaf Tablet

At the citadel of Van-Yukarı Anzaf, one of the important royal settlements built during the reign of the Urartian king Minua, during the 2001 archaeological excavations, an unsealed inventory tablet, which has no similar example in Urartian sources so far, was found. In the first publications of this unique tablet, which probably records the amount of weapons distributed, the back side was thought to be the front side. However, according to our new evaluations, it is understood that the beginning of the tablet is the other side. This new update not only led to a change in the content, but also helped to place the Anzaf Tablet in a more meaningful framework within Urartian History and bureaucratic sources. It was observed that this "unit", consisting of 15 people in total, was mostly sorted according to a hierarchical order within itself. These details observed in the content of the tablet made it possible to make some suggestions about the tablet as a whole. It is thought that there may be an indirect similarity with other bureaucratic correspondences of Urartian and some visual elements found on metal artefacts. In addition, although not directly mentioned in the tablet, it has been suggested that the personnel list mentioned only as an assumption may be about the distribution of weapons belonging to the chariots and the cavalry soldiers accompanying them.

Electrocardiogram Electrode Positioning on the Back During Echocardiography: An Exploratory Cross-Sectional Study.

ECG interpretation is sometimes difficult due to baseline fluctuations and electrode detachments when placed on the subjects' front side, leading to misinterpretation of the rhythms and phases of the cardiac cycle. We aimed to compare the differences in the wave amplitudes and respiratory variations between conventional ECG electrode positioning on the front side of patients and an alternative position on the backs of patients. Echocardiography was performed in 85 patients lying in the left lateral position. We attached the red electrode to the right clavicle, the yellow to the left clavicle, and the green to the left lateral abdomen on the front side of the patients; on the back, we attached the electrode to the right clavicle, the right upper posterior iliac spine, and the left upper posterior iliac spine. The ECG monitor amplitudes were greater on the front side compared to the back side, but the BF-breath values were smaller on the back side (6.0 pixels) compared to the front side (10.5 pixels, p<0.05). The P wave amplitude divided by the BF-breath on the back side was greater than that seen on the front side (2.8 vs. 1.8, p<0.05), whereas the QRS amplitude divided by the BF-breath was 15.0 and 16.3, respectively (p=ns). As an alternative to front-side ECG monitoring, electrodes placed on the back can help avoid misinterpretation of the ECG rhythms and the phases of the cardiac cycle due to respiration during echocardiography.

Real-time monitoring of pork freshness using polyvinyl alcohol/modified agar multilayer gas-sensitive labels

Accurate consumer perception of food packages should provide real-time feedback on any changes inside food packaging. Hence, a new multilayer gas-sensitive label (POA-12) was prepared using a layer-by-layer pouring method for simple, visual, and real-time detection of pork's freshness, while the front side was developed by immobilizing red carbon dots and fluorescein isothiocyanate in POA as indicator for volatile nitrogen, and the back side was created using bromothymol blue in POA as pH indicator. The swelling index of the multilayer gas-sensitive labels reduced from 159.19% to 148.36%, and the tensile strength increased from 25.52 MPa to 42.61 MPa. In addition, the POA-12 multilayer label showed a red-to-yellow fluorescence change as TVB-N increased from 6.84 to 31.4 and a yellow-brown-to-blue-green color change as pH increased from 5.74 to 7.24 when detecting pork samples. Thus, it provides dual-indicator monitoring that improves the accuracy and reliability of assessing the freshness of high-protein products.

Reduction of Disk Friction Loss by Applying a Fin to the Back of a Centrifugal Impeller

Abstract It is well known that the ratio of disk friction loss of low specific speed pumps is large. When the specific speed is 100 min−1, m3/min, m or less, the disk friction loss increases remarkably. In this study, focusing on the clearance flow from the diffuser outlet to the impeller outlet (This is called the outward flow) behind the centrifugal pump, a fin was installed on outer diameter side of the rotating wall on the back side of a centrifugal pump as a countermeasure, and the influence of changes in velocity distribution near the wall on disk friction loss was investigated by torque measurements, velocity measurement, and computational fluid dynamics (CFD) analysis. As a result, it was clarified that disk friction loss is decreasing by installing the fin in both torque measurements and CFD results, because the clearance flow is separated by fin and circumferential velocity is increased in the wake region of the fin in both measurements and CFD. In addition, it was clarified that disk friction coefficient (normalized torque) can be expressed as a function of the inlet swirl ratio and Reynolds number. Also, prediction equation is derived for each shape (with and without fin). According to the equation, it was found that disk friction loss reduction effect by installing a fin becomes larger when Reynolds number and the inlet swirl ratio are small.

Space Weather with Quantified Uncertainties: Improving Space Weather Predictions with Data-Driven Models of the Solar Atmosphere and Inner Heliosphere

To address Objective II of the National Space Weather Strategy and Action Plan “Develop and Disseminate Accurate and Timely Space Weather Characterization and Forecasts” and US Congress PROSWIFT Act 116–181, our team is developing a new set of open-source software that would ensure substantial improvements of Space Weather (SWx) predictions. On the one hand, our focus is on the development of data-driven solar wind models. On the other hand, each individual component of our software is designed to have accuracy higher than any existing SWx prediction tools with a dramatically improved performance. This is done by the application of new computational technologies and enhanced data sources. The development of such software paves way for improved SWx predictions accompanied with an appropriate uncertainty quantification. This makes it possible to forecast hazardous SWx effects on the space-borne and ground-based technological systems, and on human health. Our models include (1) a new, open-source solar magnetic flux model (OFT), which evolves information to the back side of the Sun and its poles, and updates the model flux with new observations using data assimilation methods; (2) a new potential field solver (POT3D) associated with the Wang–Sheeley–Arge coronal model, and (3) a new adaptive, 4-th order of accuracy solver (HelioCubed) for the Reynolds-averaged MHD equations implemented on mapped multiblock grids (cubed spheres). We describe the software and results obtained with it, including the application of machine learning to modeling coronal mass ejections, which makes it possible to improve SWx predictions by decreasing the time-of-arrival mismatch. The tests show that our software is formally more accurate and performs much faster than its predecessors used for SWx predictions.

Acceleration of laser-driven positron beam in sheath field

We propose a positron acceleration scheme in which a laser-driven positron beam is injected into a solid target hit by a laser beam and accelerated in the sheath field on the target back side. The positron beam injection and acceleration in the target have been investigated with numerical simulation. The feasibility of such an acceleration scheme was proved according to the simulation results, which show that a 10 MeV positron beam can be accelerated up to 30 MeV. The dependency of the positron beam properties on the positron injection location, injection time, and target thickness was studied. Related acceleration details were obtained and analyzed. The acceleration scheme provides a method in positron energy controlling and its related applications.

Integrated preparation of B4C–TiB2 multilayer graded ceramics with high hardness and high toughness

AbstractThe enhancement in the comprehensive performance of hardness, toughness, and strength is significant for ceramic materials. In this study, the B4C–TiB2 multilayer graded ceramics were designed and integrally manufactured by spark plasma sintering method using B4C and TiB2 as raw materials. The B4C–TiB2 multilayer graded ceramics feature a transition from the top layer with high hardness to the bottom layer with high toughness, passing through an intermediate layer. The gradient change of this material is observed in both the hardness and fracture toughness, reaching values of 36.2–28.4 GPa and 2.2–6.2 MPa m.5. The compressive strength reaches up to 2960 MPa, whereas the bending strength gets to 677 MPa in the appropriate loading direction. The structure forms a gradient pattern with high hardness on the front side, high toughness on the back side, and overall low density and high strength. This study may facilitate the development of impact‐resistant performance of lightweight materials.

Optimization of Parameters of Adaptive Spray System for Agricultural Sprayer

Introduction. When growing tall-growth crops (cereal crops in late the phases of development, corn, sunflower, etc.), there are used boom sprayers equipped with twin-fluid spray cones with fixed angles of inclination to the vertical of the spray cones. The working fluid is applied with such sprays are more intensively on the front side of the plant leaves while the intensity of covering the plants from the back side with the working fluid decreases. The development of the spray system will allow improving the quality of crop treatment with boom sprayers. Aim of the Study. The aim of the research is to determine experimentally the algorithm for changing the angles of inclination of a twin-fluid spray cone that provides the same intensity of applying working liquid to the leaves of high-growth plants. Materials and Methods. The research was carried out on a test bench by applying colored water to the front and rear sides of a tall-growth plant model moving at a specified speed. The experiment was carried out according to the method of optimal planning. The difference between the content of droplets on the front and rear sides of the tall-growth plant model was taken as an optimization parameter. Variable factors were the spray cone inclination angles and the operating speed of the sprayer. Results. The algorithm for changing the optimum values of the spray cone inclination angles depending on the sprayer speed was determined based on the equality of the first derivative of the optimization to zero parameter by the value of these angles. Discussion and Conclusion. According to the algorithm, when the sprayer operating speed increases from 1.2 to 3.2 m/s, the optimal angle of inclination to the front spray cone vertical changes linearly from 25 to 21 degrees, and the rear one ‒ from 46.7 to 57 degrees. This algorithm will allow justifying the technical specifications to develop a processor for automatic control of the spray cone inclination angles cones when the sprayer is operating.

Raman Spectroscopy Analysis for Precise Channel Temperature Estimation in AlGaN/GaN HEMT Devices

In recent years, high-electron-mobility GaN HEMTs have demonstrated significant advancements in applications such as power converters and RF amplifiers. Nevertheless, their thermal reliability poses a notable challenge, placing constraints on their power-handling capacities. This study employs micro-Raman spectroscopy to evaluate the localized self-heating-induced channel temperature. The channel temperature, determined using the single phonon modes of GaN HEMT (E2(H) &amp; A1(LO)), exhibits discrepancies and does not align with device temperature values calculated using the SiC phonon peak near the GaN channel. However, by employing both phonon modes of GaN to decouple the combined effects of joule heating and the thermoelastic effect, accurate channel temperature values are obtained, matching well with those obtained from the SiC phonon peak. The agreement between calculated temperatures from phonon modes and those obtained by heating the device from the back side enhances the credibility of the proposed method.

Performance analysis of fiber-reinforced polypropylene composite laminates under quasi-static and super-sonic shock loading conditions for impact application

In the present research, glass and basalt fiber-reinforced polypropylene composites’ behaviour in quasi-static and dynamic conditions is studied. Composites were fabricated by vacuum assisted Compression molding method. Composites failure under quasi-static tension and compressive conditions was studied along with its failure behaviour under low-velocity impact and super-sonic shock loading under dynamic conditions. The study results showed that basalt fiber-reinforced polypropylene (Basalt/PP) composite’s tensile and compressive strength is higher than glass fiber-reinforced polypropylene (Glass/PP). The Basalt/PP showed no penetration against low velocity impact (LVI) with negligible deformations till 50 J. However, the Glass/PP perforated at 50 J with various failure patterns occurring at back side. The fiber-matrix interface adhesion plays an important role in super-sonic shock loading by absorbing shock wave energy due to ductile nature of polypropylene and the two composites absorbed energy via matrix and fibers failure, no brittle failure of laminates occurred under shock loading.

A Novel Methodology to Estimate the Cell Temperature of Photovoltaic Thermal Modules: Test With Experimental Data, Prospects, and Limits

Abstract The efficient use and understanding of photovoltaic thermal (PVT) modules require accurately evaluating the temperature of their photovoltaic cells. But due to their specific composition, measuring this temperature directly is usually very complicated, if not impossible in practice. In this article, we present an original methodology to estimate the temperature of the cells of a PVT module. In order to do this, we simultaneously conduct experiments on both PVT and PV modules equipped with identical PV cells, and compare their electrical performance. The temperature of the PV module’s back side is measured and used to estimate the temperature of the PV cells. The latter is then combined with the electrical power output difference between PV and PVT modules in order to obtain, through a specifically developed thermal model, the cell temperature of the PVT module. In addition, an experimental comparative analysis of different PVT modules is presented. The methodology and the results are promising but the experimental measurements used are subject to significant uncertainties that impact the accuracy of the estimation. The model uses an innovative approach to estimate the PV cell temperature of PVT modules, and recommendations are provided to optimize experimental data measurement accuracy in order to use this model in the best possible conditions.

Development and Characterization of a Contact-Charging Electrostatic Spray UAV System

Utilizing agricultural UAVs for pesticide and insecticide spraying is an effective measure for plant protection. However, achieving effective coverage on the back side of target is often challenging. To address this issue, this study combined a contact-charging spraying system with a UAV to develop an electrostatic plant protection UAV system. Upon activating the electrostatic component, strong electrostatic effects were observed at the nozzle, altering the distribution of the liquid flow; the distribution within the liquid flow became more homogeneous, while the edge regions experienced electrostatic repulsion, leading to changes in droplet size and an increase in droplet density. In the central area, droplet size reduced from 159 μm to 135 μm, while in the edge area, it changed from no value to 120 μm. During field tests using the UAV, the results showed an increase of 1.0 m in effective spray width (at a flight height of 4.0 m), indicating that the charges and propellor wind field contributed to the diffusion of droplets towards the edges. Additionally, the droplet density increased by an average of 19.7 droplets/cm2, and the overall deposition increased by 0.12 μL/cm2, resulting in an approximate three-fold increase compared to conventional spray, which aids in insect control and reduces pesticide usage.

Corpus Callosum Length and Cerebellar Vermian Height in Fetal Growth Restriction

Plain Language SummaryIn this study, we compared ultrasound measurements of several brain structures in fetuses with reduced or normal growth. We also evaluated the correlation of the size/length of these brain structures to blood flow of several blood vessels to the brain. We found that measurements of the small brain (CVH) are larger in pregnancies with growth problems. We also found that the blood flow of the vessel in the back side of the brain (vertebral artery [VA] Doppler) is inversely correlated with the CVH. These findings add to the literature on the use of ultrasound specifically to assess brain structures in pregnancies that are affected by growth problems. Deeper understanding of these associations may help establish which pregnancies with growth problems may need the most help later in life.

Mechanical properties of an energy-efficient straw-filled honeycomb plate with cement-based skins under a hammer impact test

To promote the application of a new type of bionic energy-efficient sandwich plate with light weight and high strength in the construction field, a drop hammer impact test was adopted to determine the impact mechanical properties and influencing mechanism of fiber reinforced cement-based energy-efficient honeycomb plates with different core fillers (shredded straw and glass beads). The results show that compared with unfilled honeycomb plates (CHP), the contact force–time curves of energy-efficient plates have an obvious secondary peak, and the size of the damaged area on the back side of the upper skin is significantly reduced. Additionally, the presence of fillers in the energy-efficient plates provide a certain constraint on the deformation of honeycomb walls and skins, and slightly increase the size of the secondary peak. Furthermore, this study qualitatively reveals the influence mechanisms of the flexural stiffness of the sandwich plates, the morphology of damaged skins and fillers, the deformation pattern of the honeycomb core. The results provide a reference for subsequent research on the influence of different fillers on sandwich plates.

Vibration sensor as the basis of an equipment monitoring system

Currently, the high complexity and instability of engineering production processes leads to the need to make management decisions under conditions of uncertainty, which significantly affects the efficiency of production as a whole. Reducing uncertainty in operational production planning of machine-building industries is possible by analyzing data on the flow of technological processes collected using equipment monitoring systems, i.e. measuring and information systems. It is proposed to use vibration sensors as the main source of information to obtain reliable data on the operation of equipment. General issues regarding vibration sensors are considered and a variant of their classification according to various features is presented, such as sensitivity, operating principle, method of obtaining information, signal conversion mechanism, signal measurement method. Several versions of vibration sensors have been developed, designed to collect information about the level of vibration during processing and included in the diagnostic module for monitoring equipment operation. The first version of the printed circuit board is based on a microcontroller based on ATMega328P, designed to read MEMS accelerometer data and transmit the collected information using a wireless communication module to the operator panel for display in real time and transmission for storage and processing to the server. To charge the battery, a charge controller based on the TP4056 chip and a low-dropout linear stabilizer TPS730 are used. In the second option, the MPU9250 inertial measurement module is used, and information processing and data transmission is carried out using a specialized module NINA-B306. A printed circuit board of any of the presented options is installed in a vibration control sensor mounted on the back side of a three-jaw chuck inside the machine body. This placement of the diagnostic module eliminates the possibility of its unintentional damage while ensuring the required quality and reliability of signal transmission. The vibration sensor, fixed to the cartridge using quick-release strips, consists of a board located in the housing. Above the board there is an insert that protects the board from the battery. The housing is closed from above with a lid using screw washers through a gasket to ensure the housing is sealed. The clamping screw is used to secure the board in the case. The vibration sensor is turned on using a button. The proposed vibration sensor can be used as the basis of an measuring and information systems, because information about the level of vibration of a technological system, recorded by sensors, like a human cardiogram, provides comprehensive information about its condition. A diagnostic module built on the basis of a vibration sensor will increase the efficiency and “transparency” of machining processes and collect statistical data that allows assessing the efficiency of equipment operation.

Is the use of gonad protection protectors necessary during infants chest radiography?

Introduction and objectivesTo compare gonad doses with and without a gonad protector and to optimize the use of gonadal protectors in infants thorax radiography. Materials and methodsTwo pediatric anthropomorphic phantoms are used: an X-ray system for KXO-50SS/DRX-3724HD, and a digital radiography system for CALNEO Smart C12, with and without a gonad protector during infants thorax radiography. A real time skin dosimeter is placed on the X-ray system, and a real time skin dosimeter is inserted on the front side of the mammary gland, the front and back sides of the true pelvis level, and on the ovaries and testes. The X-ray system is irradiated 15 times using phantoms with and without a gonad protector. The measured entrance patient doses values of for the real time skin dosimeter are compared for each phantom, with and without the gonad protector. ResultsThe medium of measured entrance patient doses values for front side dose of the true pelvis level with and without the protector are 10.00 and 5.00 μGy at newborn, and 10.00 and 0.00μGy at one year, respectively. The medium of measured entrance patient doses values for the back side dose of the true pelvis level with and without the protector are 0.00 and 0.00 μGy at both newborn one year, respectively. The measured entrance patient doses cannot be detected in the ovaries and testes with or without the protector. No significant differences are observed in the measured entrance patient doses values for the front and back side doses of the pelvis, ovaries, and testes at newborn and one year, with and without the protector (p>0.05). ConclusionsNo significant difference was observed in gonad dose measurements with and without the gonad protector during infants chest radiography. We believe that gonadal protector wearing is not necessary.