Back Side Research Articles

Prediction of Critical Quality Attributes Based on the Numerical Simulation of Stress and Strain Distributions in Pharmaceutical Tablets.

Various stresses and strains are generated on the surface and inside of pharmaceutical tablets when an external force is applied. In addition, stresses in various directions can remain on the surface and inside the tablets because they are generally prepared by compaction of pharmaceutical powders using dies and punches. As it is difficult to measure the stress and strain generation in the tablets experimentally, a numerical simulation was applied by employing a finite element method (FEM). An elastic model is often used to represent stress and strain generation after loading an external force to tablets, and the Drucker-Prager cap (DPC) model has been widely recognized for representing the remaining stress distributions during the compaction of powder to tablet form. Firstly, this article describes an FEM simulation of the stress generation on the surface of the scored tablets after loading the bending force from the back side of the tablets. Next, the FEM simulation was introduced to determine the effect of diametrical compression on the stress and strain generation in the tablets by comparing the results measured experimentally. Furthermore, the residual stresses remaining inside the tablets were simulated using FEM, in which powder compaction was represented as the DPC model. A clear difference was observed in the residual stress distributions between the flat and convex tablets. This indicates that FEM simulation is useful for achieving a science-based understanding of critical quality attributes in various types of tablets.

Scientific Approaches to Solving the Problem of Joint Processes of Bubble Boiling of Refrigerant and Its Movement in a Heat Pump Heat Exchanger

The joint processes of bubble boiling and refrigerant movement in heat pump tubes are considered. A coil located on the back side of the photovoltaic panel (PVP) is used as an additional heating surface. A mathematical model of the theoretical determination of the temperature on the front surface of the PVP cooled by freon in the coil from the back side has been created. A feature of the numerical simulation of bubble boiling of refrigerant in a coil was the insufficiently detailed study of the process and the lack of references to the results obtained in earlier work. The authors have clarified the boundary conditions and assumptions for numerical simulation of the bubble boiling process of refrigerant R407C. The results were compared with the theoretically found values, and later used in the design of an energy complex consisting of a heat pump and a photovoltaic panel. The mathematical model of theoretical calculation of the PVP temperature and the methodology for constructing a numerical model of bubble boiling of refrigerant as part of the methodology for designing energy technology complexes based on the authors’ plan to present a unified methodology for energy technology complexes for desalination of seawater based on other types of renewable energy sources.

Three-Dimensional Mirror-Assisted and Concave Pyramid-Shaped Solar-Thermal Steam Generator for Highly Efficient and Stable Water Evaporation and Brine Desalination.

Although significant advances have been achieved in developing solar-driven water evaporators for seawater desalination, there is still room for simultaneously enhancing water evaporation efficiency, salt resistance, and utilization of solar energy. Herein, for the first time, we demonstrate a highly efficient three-dimensional (3D) mirror-assisted and concave pyramid-shaped solar-thermal water evaporation system for high-yield and long-term desalination of seawater and brine water, which consists of a 3D concave pyramid-shaped solar-thermal architecture on the basis of polypyrrole-coated nonwoven fabrics (PCNFs), a 3D mirror array, a self-floating polystyrene foam layer, and a tail-like PCNF for upward transport of water. The 3D concave pyramid-shaped solar-thermal architecture enables multiple solar light reflections to absorb more solar energy, while the 3D mirror-assisted solar light enhancement design can activate the solar-thermal energy conversion of the back side of the concave pyramid-shaped PCNF architecture to improve the solar-thermal energy conversion efficiency. Crucially, selective accumulation of the precipitated salts on the back side of the concave pyramid-shaped architecture is realized, ensuring a favorable salt-resistant feature. The 3D mirror-assisted and concave pyramid-shaped solar-driven water evaporation system achieves a record high water evaporation rate of 4.75 kg m-2 h-1 under 1-sun irradiation only and exhibits long-term desalination stability even when evaporating high-salinity brine waters, demonstrating its great applicability and reliability for high-yield solar-driven desalination of seawater and high-salinity brine water.

Fabrication of Efficient Perovskite Solar Minimodules with a High Geometric Fill Factor of 96% via a Nanosecond Laser

The low‐cost perovskite solar cell has become the next‐generation photovoltaic. However, compared to the high efficiency of the small‐area perovskite solar cells, the large‐area perovskite solar modules (PSMs) have still been struggling for the performance. In addition to preventing the decline in quality of each functional layer after upscaling, another key point is to construct a high geometric filling factor (GFF) for an efficient PSM. Herein, a “back‐scribing” technique is developed by using a low‐cost nanosecond laser scribing from the back side of substrates. The “back‐scribing” technology can clean up the scribing channels greatly, enabling an effective connection with a small damaged area. With precise control of the laser parameters for the scribing of P1, P2, and P3, a high GFF of 96% is achieved, resulting in a high power conversion efficiency of 19.97% with an aperture area of 16 cm2 for the PSM. By this means, the efficiency loss is minimized (<10%) when upscaling a small device to a large‐area solar module.

InGaN micro-LED array with integrated emission and detection functions for color detection application.

InGaN-based micro-LEDs can detect and emit optical signals simultaneously, owing to their overlapping emission and absorption spectra, enabling color detection. In this paper, we fabricated a green InGaN-based micro-LED array with integrated emission and detection functions. On the back side of the integrated device, when the 80 μm micro-LED emitted light, the 200 μm LED could receive reflected light to accomplish color detection. The spacing between the 80 μm and the 200 μm micro-LEDs was optimized to be 1 mm to reduce the effect of the direct light transmitted through the n-GaN layer without reflection. The integrated device shows good detection performance for different colors and skin colors, even in a dark environment. In addition, light can be emitted from the top side of the device. Utilization of light from both sides of the integrated device provides the possibility of its application in display, communication, and detection on the different sides.

Hydrodynamic behaviour of composite bucket foundation with random waves

In real sea conditions, the effect of nonlinear phenomena, such as wave run-up and wave pressure, on the foundations of offshore wind structures may threaten the safety of the platforms. This study investigated the hydrodynamic behaviour of a composite bucket foundation (CBF) under random waves. A hydrodynamic simulation model of the interaction between random waves and the CBF was developed using the renormalisation group (RNG) k-ε model, which was verified through experiments. The relationship between wave run-up and wave parameters was studied, and the distributions of wave pressure around the CBF was described. The flow field and velocity vector distribution characteristics around the CBF were analysed. The results show that two types of wave fields appear around the CBF. The maximum run-up value of the CBF is 100%–150% higher than the minimum value, and the run-up value at the back side is 50%–70% higher than the minimum value. A larger wave steepness parameter leads to a smaller wave run-up value at the location of the smallest wave run-up value. The results can provide a reference for the practical application of a CBF.

Numerical Study of Solar Chimney with Absorber at Different Locations

Heat transfer process and fluid flow in a solar chimney used for natural ventilation are investigated numerically in the present work. Solar chimney was tested by selecting different positions of absorber namely: at the back side, front side, and at the middle of the air gap. CFD analysis based on finite volume method is used to predict the thermal performance, and air flow in two dimensional solar chimney under unsteady state condition, to identify the effect of different parameters such as solar radiation. Results show that a solar chimney with absorber at the middle of the air gap gives better ventilation performance. A comparison between the numerical and previous experimental results shows fair agreement.

A Compact 2.4 GHz L-Shaped Microstrip Patch Antenna for ISM-Band Internet of Things (IoT) Applications

Wireless communication technology integration is necessary for Internet of Things (IoT)-based applications to make their data easily accessible. This study proposes a new, portable L-shaped microstrip patch antenna with enhanced gain for IoT 2.4 GHz Industrial, Scientific, and Medical (ISM) applications. The overall dimensions of the antenna are 28 mm × 21 mm × 1.6 mm (0.22λo × 0.17λo × 0.013λo, with respect to the lowest frequency). The antenna design is simply comprised of an L-shape strip line, with a full ground applied in the back side and integrated with a tiny rectangular slot. According to investigations, the developed antenna is more efficient and has a greater gain than conventional antennas. The flexibility of the antenna’s matching impedance and performance are investigated through several parametric simulations. Results indicate that the gain and efficiency can be enhanced through modifying the rectangular back slot in conjunction with fine-tuning the front L-shaped patch. The finalized antenna operates at 2.4 GHz with a 98% radiation efficiency and peak gains of 2.09 dBi (measured) and 1.95 dBi (simulated). The performance of the simulation and measurement are found to be in good agreement. Based on the performance that was achieved, the developed L-shaped antenna can be used in a variety of 2.4 GHz ISM bands and IoT application environments, especially for indoor localization estimation scenarios, such as smart offices and houses, and fourth-generation (4G) wireless communications applications due to its small size and high fractional bandwidth.

Effects of a Gap/Open Space on Hydrogen Permeation Through Double Membranes of Ni/Ni and Pd/Ni

Effects of a gap/open space between double membranes of Ni/Ni and Pd/Ni on hydrogen permeation through the double membranes are studied. For easy detection of permeated H, T is introduced. For Ni/Ni and Pd/Ni, the influence of the gap on hydrogen permeation is not appreciable, while the permeation for Ni/Pd is significantly reduced because the gap holds H2O produced by the reaction of permeated hydrogen and the surface oxide of Ni facing toward the gap; consequently, the partial pressure of H2O in the gap becomes high and subsequent reduction of the surface oxide is prohibited. From these findings, a new double-walled tube concept for the reduction of T permeation is proposed with a combination of a rather thin front tube with its back side oxidized as a permeation barrier and a thick tube as a structure material.

Ethnic and Cultural Affiliation of the Xichaogou Burial Ground Based on Materials of the Xiongnu Culture Belt Plaques

Purpose of the work is to determine the ethnic and cultural affiliation of the population that left the Xichaogou burial ground. Xichaogou is an expressive archaeological complex located in the Liaoning region of China. The uniqueness of this necropolis lies in the fact that several hundred burials of varying degrees of preservation have been recorded in it. Inventory complexes of burials include ceramics, objects made of bronze, iron and stone. The materials of the site demonstrate the features of various cultures – Xiongnu, Buyeo, Han, Xianbi and etc. Since the burial inventory of the Xichaogou burial site demonstrates multicultural features, the question of the ethnic and cultural affiliation of the population that created this site is debatable.Materials and methods. In previous works, the problem of ethnic identification of the Xichaogou burial ground was solved on the basis of certain categories of grave artefacts. In this paper, the questions of the ethnic and cultural affiliation of the Xichaogou sie are considered on the material of the belt plaques decorated in the animal style. The main reason for this choice of material is that the shape and ornament of belt plaques reflect the ethnic and cultural identity of an individual or group in nomadic cultures. 17 belt plaques were found at the Xichaogou site. The entire amount of material is divided into 3 types according to such features as shape, rim ornament (teardrop-shaped, dotted, herringbone), manufacturing technique (presence of through openwork holes), method of fastening (presence of eyelets on the back side), function as part of a belt set (presence peg). A search for analogies to the groups of belt plaques in the Xiongnu culture, identified in the materials of the Sichagou site, has been undertaken.Result. It has been established that belt plaques from the materials of the Xichaogou burial ground find analogies in the vast territory of the Xiongnu culture in Northern Eurasia.Conclusion. It can be concluded that the population that created the Xichaogou site does not belong to the Xiongnu by ethnic origin, but was strongly influenced by this culture. The population of Xichaogou was formed on the basis of the local culture of the previous period. Various and diverse cultures of the eastern part of the Liaoning and the western part of the Jilin regions also contributed to its formation. At the current stage it is possible to identify the Xiongnu and Buyeo cultural components.

Computational fluid dynamics (CFD) analysis of air-cooled solar photovoltaic (PV/T) panels

The operating temperature of the PV penal has a significant impact on its conversion efficiency. High operating temperature reduce output power under the same solar radiation conditions. This study presents a CFD analysis of a solar PV/T system with a bottom active air cooling system to optimise the PV/T system operational characteristics. The study model was developed using fluent (ANSYS) software, along with bottom air duct with an inlet/outlet manifold for uniform airflow to the back side of the PV/T system. The performance of operating parameters of PV/T system was studied for various mass flow rates of air such as 0.04, 0.06, 0.08, and 0.1 kg/sec with irradiance intensity of 800 W/m2. The maximum temperature of the operational parameters such as the Solar PV/T system top surface, cell, bottom surface, and air inlet/outlet of the PV/T system were determined to be 48.8, 48.4, 47.3, and 24.5 °C at a flow rate of air of 0.01 kg/s and 800 W/m2 intensity of solar radiation.

Errant Translation; or, Lin Shu's Don Quixote and the Paybacks of Back-Translating

AbstractLiterary back-translation, the practice of bringing a text back into the language of its source after it has passed through one or more translations, has long been overlooked. To recuperate its richly entangled global history, this essay looks to the representation of translation in Cervantes's Don Quixote and to the novel's recent back-translation based on 魔俠傳 (Moxia Zhuan; Story of the Enchanted Knight), a 1920s translation into classical Chinese by Lin Shu that itself was an indirect translation based on two eighteenth-century English editions of Cervantes's text. While foregrounding the generative labor of translators, both fictional and historical, the transnational and diachronic scope of this back-translational loop prompts us to rethink the domesticating/foreignizing binary. Taking a cue from Cervantes's metaphor of translation as the knotty back side of a tapestry, this study seeks to overturn front-facing notions of translation by approaching its history from the back.

Mooring Analysis of Ocean FarmITS (OFITS)

Ocean Farm ITS (OFITS) is a pilot project of offshore aquaculture designed by Institut Teknologi Sepuluh Nopember (ITS) which will be installed at Sidoasri Beach, Malang Districts. OFITS structure is an integration of fish cages with ecotourism facilities. This paper describes the mooring analysis for OFITS installation. The mooring configuration uses a rectangle grid consisting of 4 mooring buoys, 8 top inner mooring grids, and 14 mooring lines arranged symmetrically. The mooring line uses a type of nylon line with a size of 42 mm in diameter and 70 m in length. Five mooring lines on the front side and two mooring lines on the back side secure the moored buoy to the seafloor. The maximum capacity of buoy is 3 tons. The anchor for mooring uses an anchor with a weight of 0.25 tons for each anchor. The purpose of this analysis is to obtain the maximum tension of the mooring rope at OFITS based on extreme environmental loads. This analysis uses the time domain analysis method.

Self-recovering passive cooling utilizing endothermic reaction of NH4NO3/H2O driven by water sorption for photovoltaic cell

Power efficiency of photovoltaic cell is significantly affected by the cell temperature. Here, a self-recovering passive cooling unit is developed. The water-saturated zeolite 13X is coated on the back side of photovoltaic cell, and ammonium nitrate is dispersed as a layer to form a thin film. When heat is supplied, water is desorbed from zeolite 13X (latent cooling), and dissolves ammonium nitrate to induce endothermic reaction cooling. It is a reversible process that recovers itself at night. The unit works on the basis that the water sorption performance of porous materials is inversely proportional to temperature, and the solubility of endothermic reaction pairs increases proportionally with temperature. The average temperature of photovoltaic cell can be reduced by 15.1 °C, and the cooling energy density reaches 2,876 kJ/kg with average cooling power of 403 W/m2. We show that highly efficient passive cooling comprising inexpensive materials for photovoltaic cell could be achieved.

Phosphor thermometry for surface temperature measurements of composite materials during fire test

This study presents the implementation of phosphor thermometry method to obtain pointwise surface temperature measurements of a carbon fibers reinforced polymers composite exposed to a flame. Phosphor thermometry has previously been used to measure surface temperature in relevant applications, mainly on metallic materials. In the present study, it has been applied to measure the backside temperature of a carbon fiber Poly Phenylene Sulfide (PPS) polymer composite exposed to a flame, in order to analyze the feasibility, the limits and the advantages of the method compared to infrared thermography. Mg4FGeO6:Mn4+ thermographic phosphor is coated on the back side of the composite sample and excited with a 10 Hz repetition rate Nd:YAG laser at 355 nm. The time-resolved phosphorescence signals are processed with the lifetime approach to determine the temperature. A coating of small thickness allows the surface temperature to be measured up to 400 °C, and it is shown that this coating has no effect on the heat exchange at the surface. The comparison between the phosphor thermometry results with the ones obtained with an infrared camera shows an interesting methodology to determine the infrared emissivity of the sample at high temperature.

Effect of bias conditions on transient anode current for quasi-double-sided silicon drift detector with high energy resolution

Silicon drift detectors (SDDs) are widely applied for x-ray detection due to their remarkable energy resolution. The main contribution to energy resolution is the electrical noise of the measurement system. In addition, imperfect charge collection and ballistic deficits also deteriorate the energy resolution, which is closely related to bias conditions. However, bias condition's effect on energy resolution has been rarely reported. To investigate its effect on energy resolution, we proposed a quasi-double-sided silicon drift detector (QD-SDD) with a drift ring structure designed on the back side. QD-SDDs was simulated and verified to have more flexibility in bias conditions, achieving better electron collection efficiency and shorter collection time at higher bias voltages. Finally, the fabricated QD-SDDs were characterized using a55Fe radioactive source. The experimental results show that the energy resolution of the QD-SDD varies with different bias conditions. The optimal energy resolution is 170 eV under the optimized bias conditions.

The Phenomenology of Objectification in and Through Medical Practice and Technology Development.

Objectification is a real problem in medicine that can lead to bad medical practice or, in the worst case, dehumanization of the patient. Nevertheless, objectification also plays a major and necessary role in medicine: the patient's body should be viewed as a biological organism in order to find diseases and be able to cure them. Listening to the patient's illness story should not be replaced, but, indeed, developed by the physical examination of his body searching for the causes of his complaints. Whereas phenomenologists have so far mainly been identifying the back sides of objectification in medicine, in this paper the aim is to analyze differences between detrimental objectifications and objectifications that do not deprive the patient of his subjectivity but, rather, at least in some cases, may lead the patient to feel more at home with his body.

Experimental and numerical investigation of the thermal inertia of sugar-beet-pulp/starch based bricks enhanced with phase change materials

Due to environmental concerns, bio-based materials are being increasingly investigated and used in buildings. In general, the density of these materials, and thus their thermal inertia, is low. Thermal inertia can be beneficial for reducing the energy use of buildings by damping indoor temperature fluctuations or by reducing and delaying incoming (solar) heat through the façade.This study explores the thermal inertia of regular-sized bricks made of a sugar-beet-pulp/starch mixture (BP/S), and with 17 circular holes inside. The holes were filled either with the BP/S mixture, with air, with a stabilised phase change material (PCM) gel or with a salt-hydrate based PCM. The brick was insulated on all sides but one. Two series of experimental measurements were performed: 1.) a heating film placed at the back (insulated) side of the brick heated the brick until steady-state conditions were reached; 2.) the heated brick was then passively cooled down to ambient temperature by cutting the power to the heating film. Numerical simulations of these experimental measurements were also modelled using the COMSOL Multiphysics® software. In addition, simulations were run to study the thermal inertia of a full brick wall made out of 1 layer and of 4 layers of the BP/S brick with and without PCM, exposed to a combination of a sinusoidal outdoor air temperature fluctuation with an imposed radiation flux on the outdoor surface, representing summer conditions.The results show that the brick in which the holes were filled with phase change material had a slower temperature response and thus higher thermal inertia than the bricks in which the holes were filled with BP/S or with air. The salt-hydrate based PCM with the higher latent heat of fusion led to the slowest temperature response and highest thermal inertia. Furthermore, the calculated simulations could accurately reproduce the experimental measurements. Applying PCM in thick walls (40 cm) made of BP/S bricks however hardly affects the temperature amplitude damping and time delay of the complete wall. The addition of PCM therefore is only effective for thinner walls (10 cm).

Design and examination of a turboprop inlet with scavenge duct

The inlet with scavenge duct is an important part of turboprop aircraft engine. This type of inlet normally has a complex shape, of which the design is challenging and directly affects the flow field quality of the engine entrance and thus the engine performance. In this paper, the parametric design method of a turboprop aircraft inlet with scavenge duct is established by extracting and controlling the transition law of the critical characteristic parameters. The inlet’s performance and internal flow characteristics are examined by wind-tunnel experiment and numerical simulation. The results indicate that a flow tendency of winding up on both sides is formed due to the induction of the inlet profile, as well as a vortex pair on the back side of the power output shaft. The vortex pair dominates the pressure distortion index on the Aerodynamic Interface Plane (AIP). In addition, with the increase of freestream angle of attack, the total-pressure recovery coefficient of the inlet increases gradually while the total pressure distortion index decreases slightly. On the basis of the experimental results under different working conditions, the parametric design method proposed in this paper is feasible.

Erosion-Corrosion Behavior and Mechanism of TiAlN Coating Under Different Flow Conditions in Simulated Seawater

Erosion-corrosion behavior of high-speed steel (HSS) and titanium aluminum nitride (TiAlN) coating were investigated under different flow conditions in simulated seawater. On the front side (facing toward the direction of water flow), there was a negligible failure of the TiAlN coating, but clear marks of erosion-corrosion on the HSS. Notwithstanding, unexpected failure features were identified on the back side (back against the direction of water flow) on both specimens because the high-velocity water flow was localized at the edge and the center was high in turbulence. For the HSS, there was dominant corrosion in the center and dominant erosion at the edge. For the TiAlN/HSS coating, the dense and layered structure retards the propagation of surface cracks as the major failure into the bulk and instead promotes layer-by-layer spallation. Additionally, visible “flow marks” were observed on both specimens and can be explained by the flow-accelerated-corrosion.