Main Hole Research Articles

Tin Oxide/Amphiphilic Polymer Double‐Layered Hole Transporter for High‐Efficiency Tin Perovskite Solar Modules

AbstractAn exquisite, engineering of two poor hole transporting materials (HTMs, SnO, and PDTON) to form an excellent double‐layered HTL (SnO/PDTON) for inverted tin‐perovskite solar modules (TPSMs) is developed. SnO/PDTON has better photovoltaic performance than the commonly used PEDOT:PSS HTM when large‐area TPSMs are fabricated. Thermally evaporated SnO (that is a simple, available oxide with high hole mobility, good transparency, and adjustable frontier orbitals energy levels) film is used as a main hole transporting layer (HTL). Amphiphilic polymer PDTON (having the amine and ether groups on the side chains) film is used as a Co‐HTL, cross‐linker, passivator, and interface modification agent, as unveiled various physicochemical studies. Double‐layered SnO/PDTON with a flat morphology and good affinity toward perovskite precursor solution creates also a proper surface for depositing large‐area, high‐quality TPsk film. Therefore, TPSM (25.2 cm2 active area on 10 cm × 10 cm ITO substrate) based on double‐layered SnO/PDTON HTL achieving an efficiency over 10% with a negligible current hysteresis is reported for the first time. This study emphasizes not only the exquisite design of combining the specific characteristics of two prosaic HTMs to become a good double‐layered HTL but also gives a direction toward fabricating TPSMs to be applied in all‐perovskite tandem solar module.

Dynamic mechanical properties and failure mechanisms of rock-like materials containing main and auxiliary holes with various arrangement inclinations and spacing ratios

As a typical rock defect, circular holes significantly influence rock masses, diversifying their failure modes and ultimately weakening their bearing capacities. To study the effects of hole arrangement inclination and spacing ratio on the mechanical properties and failure mechanisms of rock-like specimens, dynamic uniaxial compressive tests were conducted by employing a modified split Hopkinson bar apparatus and digital image correlation. The results reveal a V-shaped trend in the peak stress, Young’s modulus, and absorbed energy proportion as the hole arrangement inclination increases from 0° to 90°. However, the peak strain is insensitive to changes in the hole arrangement inclination and spacing ratio. The hole spacing ratio has no significant effect on the Young’s modulus, but it causes a gradual reduction in the proportion of energy absorbed in the specimens. Moreover, shear and tensile cracks emanating from the main hole dominate the failure mode of specimens with main and auxiliary holes, as demonstrated by the resultant displacement and vertical strain contours. Rock bridges experience shear failure as the hole arrangement inclination increases from 15° to 75°, whereas the rock bridges of specimens with various hole spacing ratios tend to fail owing to tensile cracks. The interaction between main and auxiliary holes with an arrangement inclination of 0° is the weakest, suggesting that tunnel groups should be arranged perpendicularly to the direction of dynamic loading.

A method to construct a main hole structural plane model based on advanced parallel adit geological body

The advanced parallel adit of tunnel refers to the adit parallel to the direction of the main hole. Generally it is spaced tens of meters from the axis of the positive hole. During the tunnel construction, the parallel adit is driven before the main hole. Main function of it is to provide geological reference for the subsequent excavation of the main hole. At the same time, it can also help improve the long-term construction and operation and maintenance efficiency of the main tunnel. In terms of providing geological prediction information for the main tunnel, the surrounding rock information disclosed in the advanced parallel adit excavation is mainly used for surrounding rock classification and geological sketch, so as to qualitative analysis the possible geological conditions when the positive tunnel is excavated near the distance where the advanced parallel adit is located. However, the above methods cannot accurately and quantitatively analysis the geological conditions that the main tunnel will face. The lack of research on the correlation between the main tunnel and the advanced parallel adit geological conditions results in the waste of the key factor of the horizontal geological information.In this paper, the improved DBSCAN clustering algorithm is used to group the dominant structural planes according to the attitude of rock and other information. Some non-primary structural planes are screened out. The average distance between the same group of structural planes is calculated according to the average attitude of the dominant structural plane. The structural planes that are close enough are fused. Then, the axial and radial projection was carried out to form a larger range of surrounding rock fracture models. When the main tunnel is excavated to the relevant area, the situation of the surrounding rock in front can be predicted according to the model, so that the countermeasures can be made in advance. The method in this paper is applied to a tunnel project with bidirectional single line and advanced parallel adit. The prediction results after tunnel excavated show that the method in this paper is reasonable and effective.

Research and application of drilling technology for grouting transformation in coal mine strata——Taking Huainan Zhangji Mine as an example

In order to solve the problem of water disaster in coal mining and realize the safe mining of working face, the drilling technology of grouting reconstruction in coal mine strata is studied, and the key parameters in grouting construction are optimized and determined. According to the characteristics of engineering implementation, the optimization design of drilling casing program, the optimization of drilling tool assembly, the preparation of multi-type drilling fluid and the optimization of drill bit are introduced to ensure the smooth implementation of the project. According to the trajectory design requirements, the landing point of the main hole drilled into the coal seam floor to control the limestone layer was calculated. The results show that the construction technology and technical method are suitable for the multi-branch horizontal grouting well project in coal mine, which achieves the safe and efficient drilling of grouting well in coal mine, and provides useful experience for the subsequent grouting well construction in this area.

Diagnostic structure of visual robotic inundated systems with fuzzy clustering membership correlation.

The process of using robotic technology to examine underwater systems is still a difficult undertaking because the majority of automated activities lack network connectivity. Therefore, the suggested approach finds the main hole in undersea systems and fills it using robotic automation. In the predicted model, an analytical framework is created to operate the robot within predetermined areas while maximizing communication ranges. Additionally, a clustering algorithm with a fuzzy membership function is implemented, allowing the robots to advance in accordance with predefined clusters and arrive at their starting place within a predetermined amount of time. A cluster node is connected in each clustered region and provides the central control center with the necessary data. The weights are evenly distributed, and the designed robotic system is installed to prevent an uncontrolled operational state. Five different scenarios are used to test and validate the created model, and in each case, the proposed method is found to be superior to the current methodology in terms of range, energy, density, time periods, and total metrics of operation.

Megalithic Culture In Suboh Sub District Situbondo Regency

The megalithic culture in Suboh District, Situbondo Regency has its own uniqueness, namely the mortar stones, where the mortar stones in Suboh District have holes around the main hole, where the holes function to place crushed grain and there are also many archaeological remains that have not been recorded. The aim of this research is to add to the inventory of archaeological remains, social, economic and cultural systems. The type of research is qualitative research. The research methods are: (1) heuristics, (2) criticism, (3) interpretation, (4) historiography. Based on the research results, the typology of archaeological remains in Suboh District consists of three types, namely sarcophagi, stone mortars and stone monoliths with a hollow stone type. Community supporters of megalithic culture in Suboh District already know the concept of belief in the spirits of ancestors (acestor-worship). Social, economic and cultural life has recognized an egalitarian agricultural system.
 Keywords: Culture, Suboh, Megalithic

Flow characteristics of cooling nozzle for high strength after hot rolling

To further improve the cooling strength and uniformity of hot rolled strip steel after rolling and optimize the structure and process parameters of high-strength cooling equipment, this paper combined the basic structural characteristics and characteristic parameters of high-strength cooling nozzles of hot rolled strip steel, using finite element analysis software. The effect of various pressure and structural arguments on the internal flow characteristics of high-strength cooling nozzles was studied. The results show that with the increasing of the system pressure, the flow rate at the manifold outlet also increases gradually, and the fluctuation of the jet velocity increases gradually, but the flow line trend of the internal velocity is unchanged. The change in the position of the main shunt hole can affect the change in flow rate at the nozzle outlet. However, when the pressure is greater than 0.3 MPa, the fluctuation range of the flow rate at the slot outlet tends to be larger. The relevant results provide some reference for the design of high-strength cooling equipment in hot rolling.

An Integrated Geophysical and Unmanned Aerial Systems Surveys for Multi-Sensory, Multi-Scale and Multi-Resolution Cave Detection: The Gravaglione Site (Canale di Pirro Polje, Apulia)

Gravaglione represents one of the main swallow holes of the Canale di Pirro, low Murge, Apulia region, Italy. Here, after an intense rainstorm, a huge volume of rainwater accumulates at the surface. The drainage dynamics suggest that the Gravaglione could be part of a large, and potentially unknown, karst system. To verify this hypothesis and to acquire useful information on the possible karst environment features, an integrated aerial and geophysical multiscale and multimethod approach was applied. In particular, aerial photogrammetry, ground penetrating radar measurements and electrical resistivity tomography surveys were hence conducted and integrated to potentially detect the caves, define the subsurface volume possibly affected by karst systems and to verify the existence of links between the surficial morphology and the subsoil structure. The results provided interesting insights regarding the presence of a complex karst system extending up to 200 m b.g.l. and with a marked 3D nature. Overall, the Gravaglione case study demonstrates the geophysical approach validity and poses the basis for the development of an expeditive and low-cost high-resolution strategy for detecting and characterizing karst caves.

Collapsar Black Holes Are Likely Born Slowly Spinning

Collapsing stars constitute the main black hole (BH) formation channel, and are occasionally associated with the launch of relativistic jets that power γ-ray bursts (GRBs). Thus, collapsars offer an opportunity to infer the natal (before spin-up/down by accretion) BH spin directly from observations. We show that once the BH saturates with a large-scale magnetic flux, the jet power is dictated by the BH spin and mass accretion rate. Core-collapse simulations by Halevi et al. and GRB observations favor stellar density profiles that yield an accretion rate of , weakly dependent on time. This leaves the spin as the main factor that governs the jet power. By comparing the jet power to characteristic GRB luminosities, we find that the majority of BHs associated with jets are likely born slowly spinning with a dimensionless spin of a ≃ 0.2, or a ≃ 0.5 for wobbling jets, with the main uncertainty originating in the unknown γ-ray radiative efficiency. This result could be applied to the entire core-collapse BH population, unless an anticorrelation between the stellar magnetic field and angular momentum is present. In a companion paper, Jacquemin-Ide et al., we show that regardless of the natal spin, the extraction of BH rotational energy leads to spin-down to a ≲ 0.2, consistent with gravitational-wave observations. We verify our results by performing the first 3D general-relativistic magnetohydrodynamic simulations of collapsar jets with characteristic GRB energies, powered by slowly spinning BHs. We find that jets of typical GRB power struggle to escape from the star, providing the first numerical indication that many jets fail to generate a GRB.

Design optimisation and experimental verification of a UAV’s landing gear buffer

The landing gear is a critical aircraft system that absorbs the kinetic energy of the vertical load and reduces the aircraft’s impact at touchdown. This paper proposes a hybrid optimisation method for further optimising the buffer performance of a mature UAV’s main landing gear. This method combines a propagation (BP) neural network method with a genetic algorithm (GA). A landing gear dynamics simulation model is established based on the software LMS Virtual.Lab Motion, and validate the model with tests. The optimisation model is established using a BP neural network and solved using a genetic algorithm. The maximum vertical load, the efficiency coefficient of buffer, and the efficiency coefficient of buffer system are used as the optimisation targets. The air chamber initial gas pressure, initial volume of buffer, and diameter of main oil hole are selected as the optimisation parameters, and the values after optimisation are 148 MPa, 165.2 mL, and 3.17 mm, respectively. The results show that the efficiency coefficient of buffer is increased by 3.7% and the efficiency coefficient of buffer system is increased by 1.13% and the maximum vertical load decreased by 0.6%, which indicated that the hybrid optimisation method is effective for landing gear buffering performance.

A pre-pandemic analysis of the global fertiliser trade network

In this paper a complex network analysis of global fertiliser trade during the period 2014–2018 has been carried out. The goal is to study its structure both at the global and local level, identifying communities and main players, motifs, structural holes and brokerage roles. The persistency and variability of trade links have also been analysed. The Global Fertiliser Trade Network is characterised as a small-world network with scale-free properties, revealing a high level of reciprocity and centralisation. The network has a core-periphery structure consisting of five core countries (namely EU, USA, China, Brazil, and the Russian Federation) which trade among themselves and with most periphery countries, which have sparse connections between them. The interregional and community analyses indicate a moderate level of heterophily and a geographical component in the trade communities. The network also exhibits an overall tendency toward intransitivity which implies a strategic advantage for countries that act as brokers. This study provides a clear picture of the situation prior to the COVID pandemic and the Ukraine military conflict. Those events have affected global fertiliser trade in a way that has yet to be fully ascertained. The purpose of this paper is to firmly establish a reference against which to gauge the direction and magnitude of those changes.

In Situ High-Pressure Raman Spectroscopic, Single-Crystal X-ray Diffraction, and FTIR Investigations of Rutile and TiO2II

In ultrahigh-pressure (UHP) metamorphic rocks, rutile is an important accessory mineral. Its high-pressure polymorph TiO2II can be a significant indicator of pressure in the diamond stability field. In the present study, in situ high-pressure Raman spectroscopic measurements of natural rutile in UHP eclogite from the main hole of the Chinese Continental Scientific Drilling Project (CCSD) have been conducted up to ~16 GPa. Rutile and recovered TiO2II have also been analyzed via single-crystal X-ray diffraction and FTIR spectroscopy. The results indicate that (1) the phase transition from rutile to baddeleyite-type TiO2 terminates at about 16 GPa under compression at ambient temperature; (2) the metastable TiO2II in the exhumated UHP rocks formed during deep continental subduction can be characterized by a highly distorted octahedral site in the crystal structure. X-ray powder diffraction analyses (with Cu Kα radiation) at ambient conditions are sufficient for identifying the lamellae of TiO2II within natural rutile based on the angles (2θ) of two strong peaks at 25.5° and 31.5°; (3) rutile and recovered TiO2II in the continental slabs can contain certain amounts of water during deep subduction and exhumation. The estimated water contents of rutile in the present study range from 1590 to 1780 ppm of H2O by weight. In the crystal structure of TiO2II, hydrogen can be incorporated close to the long O-O edges (>2.5143 Å) of the TiO6 octahedra. Further studies on the pressure–temperature stability of hydroxyls in rutile and TiO2II may help to understand the transportation and release of water in subducted continental slabs.

Study on Plasma Combustion in Aeroengine Combustor

To explore the plasma combustion affect the performance of the aircraft engine combustor, 16 components in the aviation kerosene 25-step reaction mechanism on the basis of considering step 9 simplify the plasma reaction mechanism, set up considering plasma electron collision reaction excited state relaxation and excited states participate in the process of chemical reaction kerosene combustion reaction model, The numerical calculation of the combustion process in the combustor is carried out, and the numerical calculation results of the combustion process with or without plasma combustion are compared and analyzed. The results show that the core reaction zone of the combustion chamber fuel is relatively forward under the conventional mechanism condition, and the average temperature of the combustion chamber outlet is 1910K. The temperature and high-temperature zone of the combustor where the plasma mechanism is applied are mainly distributed in the combustor outlet, mixing hole and main combustion hole, and the average temperature is 2050K. Meanwhile, the kerosene combustion efficiency also increases from 82.4% to 90.1%, increasing by about 7.7%. The results show that the addition of a plasma mechanism can deepen the chemical reaction degree of kerosene and release more heat to improve the combustion efficiency of kerosene.

Fracability Evaluation Method of a Fractured-Vuggy Carbonate Reservoir in the Shunbei Block.

The fracability of carbonate reservoirs is a key indicator for evaluating whether reservoirs can be effectively fractured. Taking the fractured-vuggy carbonate reservoir in the Shunbei block as an example, the microscopic characteristics and mechanical properties of this reservoir were analyzed. The test results showed that the core microstructure is relatively dense, the micropores and microfractures are developed, and the mineral composition is characterized by "high carbonate and few impurities". The compressive strength, Young's modulus, and Poisson's ratio of the rock increased with the increase in the confining pressure. Poisson's ratio is more sensitive to confining pressure than Young's modulus and shows the ductile transformation tendency from a low confining pressure to a high confining pressure. Considering the difficulty of forming a complex fracture network, we put forward a "fracture propagation factor" equation constructed with five main factors, including brittleness, fracture toughness, natural fracture, hole size, and horizontal stress difference, and then the fracture propagation factor of Yijianfang formation is calculated to be greater than 0.5. It is known that the Yijianfang formation has higher fracability. On this basis, combined with the construction parameters, a model for evaluating the fracability of a fractured-vuggy carbonate reservoir was established. The comprehensive fracability of four wells in the Shunbei block was calculated by the model. From the calculation results, the comprehensive fracability index of SHB43X was 0.5406 and greater than that of the other three wells, which has a high correlation with the production after fracturing.

Development of a Natural Draft Metal Biomass Cookstove for Community Kitchen

Present work reports details of the design, fabrication, and laboratory testing of a natural draft metal biomass cookstove for a community kitchen. Heat transfer and fluid flow considerations along with experimental data available in the literature are used for the design of the community cookstove. The summation of pressure drop in different sections of the cookstove is compared with the outside pressure drop for the system using buoyancy considerations. The cookstove is fabricated as per the dimensions finalized during the design stage. Laboratory testing of the cookstove is conducted according to Bureau of Indian Standards (BIS) protocol. The tests are conducted under different conditions of main air hole closing viz. 0%, 25%, 75% and 100%. Each test is replicated thrice and an analysis of data is performed using a student’s t-test. The efficiency of cookstove is found to be about 42% i.e., well above the BIS limit of 25% for natural draft metal cookstove. The effect of insulation on the outer body of cookstove is studied experimentally. It is found that the efficiency enhances by about 5.3% due to insulation. The authors found that provision of primary and secondary air holes play a very important role in the performance of the cookstove. When 100% main air holes are closed, the average efficiency of the cookstove is found to be poor (27.3%) due to no supply of secondary air to the combustion chamber of the cookstove.

Evolution mechanism of temperature field of the frozen wall of the vertical shaft under cold energy extraction

ABSTRACT To verify the feasibility of extracting the excess cold energy of the frozen wall and clarify the variation mechanism of the frozen wall temperature field during the cold energy extraction process, this study carried out the field extraction experiment of the excess cold energy of the frozen wall in the central air shaft of Linhuan Coal Mine. The results showed that the maximum temperature difference of salt liquid before and after cold extraction was 19.9°C. The extraction effect of the frozen wall cold energy was very significant. Through numerical simulation, this study reproduced the whole process of cold energy extraction of the frozen wall, and find that on the 30th day of cold energy extraction, the average temperature increase of the frozen wall under the scheme of main row hole plus auxiliary hole cold energy extraction is 2.2 times that of only main row hole cold energy extraction. The main surface temperature of the frozen wall shows a “wavy” distribution, and the lowest point is in the central area of the frozen wall. The main surface temperature rises with the increase of cold energy extraction time. And on the 30th day of cold energy extraction, the temperature in the east, south, west, and north of the frozen wall increased by 5.8°C, 12.5°C, 8.5°C, 11.1°C, respectively. Meanwhile, it is found that the higher the salt temperature, the higher the thermal conductivity of the frozen wall, and the faster the average temperature increases.

In-situ temperature monitoring during rotary ultrasonic-assisted drilling of fiber-reinforced composites

Drilling polyetherimide composite is difficult due to the anisotropic and inhomogeneous structure of fiber and matrix. Drilling of fiber-reinforced composites is a thermo-mechanical friction procedure required in various aerospace and automotive applications. The major reason for component rejection during manufacturing processes is due to thermal damage and temperature elevation defects such as delamination and fiber pullout caused during drilling. This work aims to propose a rotary ultrasonic-assisted drilling technique for composite materials to reduce thermal damage using diamond-impregnated tools. The influence of drilling parameters such as rotational speed, feed rate, abrasive grit size, and ultrasonic power was monitored on temperature elevations. The temperature was monitored using thermocouples located at different distances of 1.0, 2.0, and 3.0 mm from the main drilled hole. The response surface methodology was used for the design of experiments during the drilling of composite material and optimization of process parameters was carried out using analysis of variance. Rotational speed and abrasive grit size were observed to have the highest contribution of 42% and 37% for temperature elevations respectively. It was witnessed that temperature increases with an increase in rotational speed, feedrate, and abrasive grit size. Increasing the ultrasonic power during drilling temperature can be minimized. The temperature elevations at the tool-composite interface can be reduced by leveraging the application of rotary ultrasonic-assisted drilling.

The influence of geometric algebra in surgical practice of sleeve gastrectomy-single center experience.

Laparoscopic surgery could be considered as an art of geometric algebra. However, very little is studied in the context of bariatric surgery. The current study aims to explore the possible influence concept of geometric algebra on the surgical process in the overweight and obese patients in the setting of laparoscopic sleeve gastrectomy (LSG). During the study period, clinical data of subjects who underwent LSG was retrospectively analyzed. Parameters examined include body mass index (BMI), umbilical-xiphoidal interval (U-X) and umbilical-fundus (U-F) interval. In this study, LSG was performed via central view approach (C) and left view approach (L). In both groups, the body surface projection points of viewing hole (V), main and accessory operating holes (O1 and O2) and surface display of fundus (F) were connected to form a geometric figure. The accessibility of the surgical instrument into the fundus, the need for elongated instruments and related intra- and post-operative parameters were noted. The overweight and obese subjects showed a significant increased U-X and U-F interval compared to the non-obese subjects. The length of both U-X and U-F interval were correlated with the BMI. The geometric figure is quite different between L and C approach with significant increase of area of quadrangle. Significant longer O1-F, O2-F and V-F interval was calculated in C approach of patients and thus the elongated instruments were frequently required. The integration of the concept geometric algebra with the proper selection of troca may provide a better surgical experience and smooth surgical process.

Unconfined propeller scour in waterways: The role of flow intensity

Flow intensity represents an important input to be investigated in the ship propeller jet scouring process in ship maneuvering areas, waterways path, and mooring in navigation channels. Although the still water condition is not realistic, since it induces modifications in the canonical propeller jet scouring process in waterways, several studies were based on this assumption and only a few papers focused on the influence of the flow intensity are present in the technical literature. In this work, an experimental campaign aimed at exploring the flow intensity effects on the propeller jet and related scour was carried out. In particular, three flow intensities combined with different propeller submergence depths were tested. The experimental results are shown in terms of longitudinal and cross-sectional scoured bed profiles, and empirical equations to compute the main scour hole dimensions are proposed. Moreover, scour hole bathymetries were analyzed by spectral analysis to estimate characteristics length scales. In order to increase the detail on the fluid mechanics analysis to explain the influence of the flow intensity on the evolution of the scour hole and obtain an insight into the influence of the boundary effect on the flow field, Reynolds-Averaged Navier–Stokes simulations were performed over the three-dimensional scoured bathymetry, acquired at the equilibrium stage, and over the horizontal boundary, representing the earliest stages of the scouring process. The good agreement between the numerical results and the measured velocities at the equilibrium stage allowed also the simulations over a flat bed in the same hydraulic conditions. These represent the beginning of the scour process in the case in which the propeller blades are close to the bottom. As to the authors' knowledge, the last configurations were never simulated before, owing to the difficulties in managing the computation of a moving mesh close to a solid boundary. The results show, for the first time numerically, the plane boundary effects on the characteristics of propeller jets with and without an incoming flow.

Numerical investigation of area ratio on sister hole applications at a constant exit area

A numerical study was performed to investigate the effect of the area ratio at sister hole applications on film cooling effectiveness and flow structure. Two secondary coolant holes are placed on both sides of the main hole at a lateral distance of one main hole diameter. Four different area ratios (AR = 2–5) between the main hole and sister hole were studied. A single cylindrical hole was also studied for comparison and baseline. The structured mesh was generated and realizable k-ε turbulence model with scalable wall function was used in these simulations. Blowing ratios of 0.25, 0.50, 0.80, and 1 were simulated to evaluate the effect of sister holes in practical applications. The centerline cooling effectiveness and laterally averaged cooling effectiveness are studied as well as temperature contours and streamlines at two different streamwise locations (x/D = 1 and x/D = 3). The area ratio on sister hole application has an important effect on cooling effectiveness as the sister hole exit area affects the Anti- Counter Rotating Vortex intensity (A-CRVP vorticity) and size. The positive effect of the sister hole is more pronounced with the increasing blowing ratio. Lower are ratios such as AR = 2 and AR = 3, decrease the vorticity of the CRVP around %30 which directly affects the cooling effectiveness. The results of this study showed area ratio, as well as lateral distance between main hole and sister hole centers heavily affects the cooling effectiveness, the lower area ratios are more efficient for film cooling.