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Discontinuities in rock mass behave as weak planes, and it is crucial to understand their behavior when assessing the stability of underground structures. Shear characteristics of discontinuities are usually affected by the interaction among overburden stress, tectonic stresses, water pressure by groundwater level and temperature at depth. Thus, it is necessary to evaluate the variation of the frictional properties of rock discontinuities at different conditions. In this study, a series of shear tests were carried out for three types of rocks (Daejeon granite, Goheung diorite, and Linyi sandstone) having a saw-cut surface to investigate the shear characteristics of a rock discontinuity under various thermal-hydro-mechanical conditions in a triaxial compression chamber. In addition to the tests on saw-cut specimens, the effect of surface roughness on shear characteristics was examined. Cement mortar was used to reproduce identical rough discontinuities having JRC values of 2 and 12. The testing conditions were determined considering in situ conditions at the vicinity of underground opening such as radioactive waste disposal facilities, enhanced geothermal systems, and oil reservoirs. The experimental results were analyzed based on Coulomb’s and Patton’s failure criterion. It was observed that the shear characteristics of rock discontinuities were sensitive to confining and water pressure but not to a temperature below 80 °C. XRD analysis and SEM observation were performed to identify the mechanism responsible for the change of friction angle. Clay minerals having a layer lattice structure that results in weakening of the bonding of minerals may have reduced the friction angle.

The current paper investigates two particular features of a novel rotary split engine. This internal combustion engine incorporates a number of positive advantages in comparison to conventional reciprocating piston engines. As a split engine, it is characterized by a significant difference between the expansion and compression ratios, the former being higher. The processes are decoupled and take place simultaneously, in different chambers and on the different sides of the rotating pistons. Initially, a brief description of the engine’s structure and operating principle is provided. Next, the configuration of the compression chamber and the sealing system are examined. The numerical study is conducted using CFD simulation models, with the relevant assumptions and boundary conditions. Two parameters of the compression chamber were studied, the intake port design (initial and optimized) and the sealing system size (short and long). The best option was found to be the combination of the optimized intake port design with the short seal, in order to keep the compression chamber as close as possible to the engine shaft. A more detailed study of the sealing system included different labyrinth geometries. It was found that the stepped labyrinth achieves the highest sealing efficiency.

Purpose To ascertain the benefits of practicing shunt pumping test on a validated experimental model. Methods A validated experimental model of shunt was used and 25 medical professionals were asked to assess the block in the model where artificial blocks were created. The assessment was repeated after the participants had practiced on the same model. The performance of participants before and after practice was compared and statistically evaluated. Results The ability to predict the status of shunt showed an improvement in all scenarios after practice. The odds ratio for predicting a blocked shunt before and after practice was 7.25 (95% credible interval: 1.50–21.01). The odds ratio for predicting a functional shunt before and after practice was 8.81 (95% credible interval of 1.64 to 13.65). Conclusion Practicing on the experimental model significantly improves the ability to predict the status of shunt. Training of primary caregivers on similar shunt models based on the shunts used in respective centers can improve an early detection of shunt block and reduce reliance on more invasive and expensive evaluation modalities.

This paper describes the significance of exploiting and developing renewable energy under the current circumstance of fossil energy shortage. The paper introduces the working principle and the overall structure of the circular mold briquetting machine. In the transmission and feeding mechanism, the “one shaft” structure is used. The “Double-roller” is symmetrically arranged in the compression chamber, and the combination circular mold is adopted. It is shown in the structural analysis that the briquetting machine is of simple structure, high work efficiency, and low cost. Moreover, it can be conveniently repaired and replaced. The structural analysis provides significant theoretical basis for the optimal design of the briquetting machine.

M‐mode graphically displays the movement of cardiac structures along one line swept by the probe. It can assess valvular opening, chamber size, and subtle abnormalities of cardiac motion. It has a very high temporal resolution and rapid sampling rate that allows recording of subtle motion and timing of cardiac events. On M‐mode, the right ventricular (RV) continues to collapse after systole, while the left ventricular (LV) is expanding. This is the most specific and latest tamponade sign. Tamponade may occur as a result of a localized effusion compressing one particular chamber, such as RV, LV, left atrial (LA), right atrial (RA), or pulmonary veins, as after cardiac surgery. This is more difficult to diagnose, and only some of the tamponade echocardiographic signs are seen. Transesophageal echocardiography (TEE) may be more helpful in showing the localized effusion and cardiac chamber compression.

Peeling wheat yields higher-quality flour. During processing in a flaking machine, wheat kernels undergo continuous compression within the machine’s chamber. As this compression persists, damage to the kernels intensifies and accumulates, eventually leading to kernel breakage. To study the damage characteristics of wheat kernels during peeling, this study established a continuous damage model based on Hertzian contact theory and continuous damage theory. The model’s accuracy was validated through experiments, culminating in the calculation of critical parameters for wheat peeling. This study focused on different wheat varieties (Ningmai 22 and Jichun 1) and kernel sizes (the thicknesses of the small, medium, and large kernels were standardized as follows: Ningmai 22—2.67 ± 0.07 mm, 2.81 ± 0.07 mm, and 2.95 ± 0.07 mm; Jichun 1—2.98 ± 0.11 mm, 3.20 ± 0.11 mm, and 3.42 ± 0.11 mm). Continuous compression tests were conducted using a mass spectrometer, and critical damage parameters were analyzed and calculated by integrating the theoretical model with experimental data. The test results showed that the average maximum crushing force (Fc) for small, medium, and large-sized kernels of Ningmai 22 was 96.71 ± 2.27 N, 110.17 ± 2.68 N, and 128.41 ± 2.85 N, respectively. The average maximum crushing deformation (αc) was 0.65 ± 0.08 mm, 0.68 ± 0.13 mm, and 0.77 ± 0.17 mm, respectively. The average elastic–plastic critical pressure (Fs) was 50.21 N, 60.13 N, and 59.08 N, respectively, and the average critical values of elastic–plastic deformation (αs) were 0.37 mm, 0.38 mm, and 0.39 mm, respectively. For Jichun 1, the average maximum crushing force (Fc) for small-, medium-, and large-sized kernels was 113.34 ± 3.15 N, 125.28 ± 3.64 N, and 136.15 ± 3.29 N, respectively. The average maximum crushing deformation (αc) was 0.75 ± 0.11 mm, 0.83 ± 0.15 mm, and 0.88 ± 0.18 mm, respectively. The average elastic–plastic critical pressure (Fs) was 58.11 N, 64.17 N, and 85.05 N, respectively, and the average critical values of elastic–plastic deformation (αs) were 0.45 mm, 0.47 mm, and 0.52 mm, respectively. The test results indicated that during mechanical compression, if the deformation is less than αs, the continued application of the compression load will not result in kernel crushing. However, if the deformation exceeds αs, continued compression will lead to kernel crushing, with the required number of compressions decreasing as the deformation increases. If the deformation surpasses αc, a single compression load is sufficient to cause kernel crushing. Since smaller wheat kernels are more susceptible to breakage during processing, the peeling pressure (F) within the chamber should be controlled to remain below the average elastic–plastic critical pressure (Fs) of small-sized wheat kernels. Additionally, the kernel deformation (α) induced by the flow rate and loading in the chamber should be kept below the average elastic–plastic critical deformation (αs) of small-sized wheat kernels. This paper provides a theoretical foundation for the structural design and optimization of processing parameters for wheat peeling machines.

The present investigation is directed towards synthesis of zinc oxide (ZnO) nanoparticles and steady blending with soybean biodiesel (SBME25) to improve the fuel properties of SBME25 and enhance the overall characteristics of a variable compression ratio diesel engine. The soybean biodiesel (SBME) was prepared using the transesterification reaction. Numerous characterization tests were carried out to ascertain the shape and size of zinc oxide nanoparticles. The synthesized asymmetric ZnO nanoparticles were dispersed in SBME25 at three dosage levels (25, 50, and 75 ppm) with sodium dodecyl benzene sulphonate (SDBS) surfactant using the ultrasonication process. The quantified physicochemical properties of all the fuels blends were in symmetry with the American society for testing and materials (ASTM) standards. Nanofuel blends demonstrated enhanced fuel properties compared with SBME25. The engine was operated at two different compression ratios (18.5 and 21.5) and a comparison was made, and best fuel blend and compression ratio (CR) were selected. Fuel blend SBME25ZnO50 and compression ratio (CR) of 21.5 illustrated an overall enhancement in engine characteristics. For SBME25ZnO50 and CR 21.5 fuel blend, brake thermal efficiency (BTE) increased by 23.2%, brake specific fuel consumption (BSFC) were reduced by 26.66%, and hydrocarbon (HC), CO, smoke, and CO2 emissions were reduced by 32.234%, 28.21% 22.55% and 21.66%, respectively; in addition, the heat release rate (HRR) and mean gas temperature (MGT) improved, and ignition delay (ID) was reduced. In contrast, the NOx emissions increased for all the nanofuel blends due to greater supply of oxygen and increase in the temperature of the combustion chamber. At a CR of 18.5, a similar trend was observed, while the values of engine characteristics were lower compared with CR of 21.5. The properties of nanofuel blend SBME25ZnO50 were in symmetry and comparable to the diesel fuel.

Zonal disintegration is the phenomenon of cyclical rupture zone and nonrupture zone in the surrounding rock of a deep‐buried chamber, which is different from that of a shallow chamber. Based on the finite difference software FLAC3D, the numerical simulation of surrounding rock with different mechanical parameters was conducted by using the SU model (Bilinear Strain‐Softening Ubiquitous‐Joint). The influences of buried depth, cohesion, and internal friction angle of surrounding rock on zonal disintegration were analyzed to reveal the influence law. The results show that: (1) after the chamber excavation, multiple rupture zones gradually extend from the chamber surface or adjacent periphery to the deep surrounding rock. In the extension process, a single rupture zone may be forked into two or even multiple rupture zones, which cross each other and form the zonal disintegration zone. (2) Zonal disintegration is affected by both σ (in situ stress) and Ucs (uniaxial compression strength). Smaller Ucs and larger σ will lead to zonal disintegration. (3) The zoning fracture is not obvious in the case of σ≤Ucs$\\sigma \\le {U}_{\\mathrm{cs}}$ . In the reverse case, zoning fracture appears remarkably in the surrounding rock around the chamber. These results reveal the influence law of zonal disintegration and provide theoretical support for the design of deep‐buried chambers. Based on the finite difference software FLAC3D, the numerical simulation of cavern surrounding rock under different working conditions was carried out by using Bilinear Strain‐Softening Ubiquitous‐Joint Model (Subi). The effects of buried depth, cohesion and internal friction angle of surrounding rock on the discontinuous deformation are analyzed, and the generation and evolution mechanism of discontinuous deformation of surrounding rock is revealed.

Intercellular deformations, caused by increasing levels of compression applied by a pressure chamber to an organ covered with a plastic sealant and evaluated according to the internal atmosphere removal rate, were observed in carrots ( Daucus carota L. sativa), potatoes ( Solanum tuberosum L.) and sweet-potatoes ( Ipomea batatas L. Lam). The maximum internal gas volume removed in these kinetic assays was close to the intercellular air volume ( V g ) measured by the pycnometric method. Presumably a compression larger than the average organ turgor was required to remove all V g and above this point the cells should become completely flattened against each other. The intercellular deformation caused by a compressing load, observed by constant pressure volumetry, induced a reduction in the endogenous O 2 concentration at the stressed area, according to polarographic measurements. Cellular deformations and eventual V g flooding caused by water movement from the symplasm to the apoplasm of externally compressed organs were distinct from the usual pressure chamber assays, where all cells are exposed to homogeneous gas pressurization, without the development of forces to cause large cellular deformation and intercellular flooding. These gas transport restrictions were suggested as potential causes for post harvest deterioration in fragile commodities subjected to compression.

The combination of an alternative alcohol-based fuel and a pre-chamber (PC) combustion process in a spark-ignition (SI) engine allows for both an extension of the lean limit and an increase of the indicated efficiency, while simultaneously achieving low engine-out emissions. The orientation of the PC orifices is crucial for the flow field inside the PC. Orifices with different swirl angles have already been investigated. However, the influence of the orifice offset from the PC center with a fixed swirl angle has not been part of previous research. This study presents investigations of ethanol-fueled combustion systems on a thermodynamic SI single-cylinder engine (SCE) for passenger car applications with a compression ratio (CR) of 16.4. Three active PC layouts with different orifice offsets were investigated. Their combustion behaviors were compared to that of a conventional SI combustion concept. In particular, variations of the relative air/fuel ratio (λ) were performed at both part-load and high-load engine operations. The influence of the different orifice offsets in terms of both the maximum achievable lean limit and the indicated efficiency was found to be small since the combustion behavior was similar for all three PC layouts, and no significant differences in terms of both the lean limit and the indicated efficiency were observed. Compared to the SI configuration, the PC configurations achieved higher maximum indicated efficiencies. At an engine speed of 2000 1/min and an indicated mean effective pressure (IMEP) of 15 bar, a maximum indicated efficiency of 46.5% was achieved with a λ of 1.8. Moreover, a maximum λ of 2.0 was achieved with a PC configuration, while the maximum achievable λ with SI was 1.7. This work provides insights that help to understand the influence of the PC orifice offset on the combustion of an active PC application and shows approaches for future research.