Vertical Holes Research Articles

Study on Extraction of Cold Air through a Vertical Hole from a Large Snow Mound ― Functional approximation of α^X and F^X with separated αF values and their applications―

Study on Extraction of Cold Air through a Vertical Hole from a Large Snow Mound ― Functional approximation of α^X and F^X with separated αF values and their applications―

The Concept of a Manned Base Using the Lunar Vertical Holes and Lava Tube

The Concept of a Manned Base Using the Lunar Vertical Holes and Lava Tube

Improved thermal conductivity of ceramic-epoxy composites by constructing vertically aligned nanoflower-like AlN network

Ceramic-polymer composites with good thermal conductivity, low dielectric constant and low dielectric loss have significant applicability in microelectronics and wireless communication systems. However, traditional thermal conductivity ceramic-polymer composites – realized simply through the random dispersion of spherical or near-spherical ceramic powder fillers – cannot have both high thermal conductivity and good electrical insulation, which greatly hinders their practical application. In this study, we first used metallic Al powder corroded by ultrasonic cavitation as the aluminium source, and then prepared spherical aluminium nitride (AlN) powders with many nano petals grown on the surface using the melamine-assisted nitriding method; subsequently, the ice-template method was utilized to construct a three-dimensional (3D) AlN framework with vertical columnar holes, and finally, nanoflower-like AlN-epoxy (EP) composites were prepared by vacuum infiltration. The unique nano petal structures on the surface of AlN powder and the welding between AlN nano-petals during vacuum sintering increased the contact area between nanoflower-like AlN powders and lowered their contact thermal resistance. Moreover, the construction of vertical AlN channels was conducive to the formtion of thermally conductive pathways in AlN-epoxy composites. As a result, we obtained ceramic-polymer composites with improved thermal conductivity, among which the composites with 20 vol% nanoflower-like AlN powder had the highest thermal conductivity – 2.26 W/m·K – compared to a pure matrix, which is equivalent to an enhancement of 830%.

Internal limiting membrane peeling for large macular hole: Tailoring the rhexis to the shape of the hole.

Purpose:To report a simple modification of internal limiting membrane (ILM) peeling tailored to the shape of the macular hole to improve the closure rates.Methods:This is a single-center interventional case series. conducted between 2016 and 2020. The minimum follow-up was 4 months. All surgeries were performed by one surgeon. Twenty consecutive patients (21 eyes) with large idiopathic macular holes (horizontal diameter: ≥600 μm) were enrolled; vertical hole diameters were also measured using spectral-domain optical coherence tomography (OCT). Following vitrectomy, ILM peeling was performed over a horizontally oval area (additional 1 disc-diameter temporally); perfluoropropane gas (C3F8, 15%) tamponade was used. Hole closure and change in best-corrected visual acuity (BCVA) were monitored after absorption of the gas. Preoperative and postoperative visual acuities were compared using paired t-test. IBM SPSS (ver. 26) was used for analysis.Results:The macular holes were horizontally oval rather than circular without exception: mean horizontal and vertical diameters were 714 μm (range: 600–1020 μm) and 602 μm (490–844 μm), respectively. Following vitrectomy, macular hole closure was obtained in 20/21 eyes by the last follow-up (mean: 28 months, median: 34 months; range 4–48 months). Mean Snellen BCVA improved from 20/200 to 20/63 (P < 0.0001).Conclusion:All the macular holes in the study were observed to be horizontally oval. A corresponding horizontal enlargement of the ILM rhexis yielded excellent anatomical and satisfactory visual outcomes.

Experimental and theoretical modeling for predicting bending moment capacity of T-head square-neck one-side bolted endplate to tube column connection

One-side bolting technology is expected to play an important role in the bolted connection between H-beam and Hollow Section Steel Column (HSSC). By evaluating the possible defects of the existing one-side bolts in terms of cost, installation, and mechanical properties based on plentiful reported studies, a new type of T-head Square-neck One-side Bolt (TSOB) was proposed, which has a simple construction, can adapt to the rough installation manners in the construction site, and no additional auxiliary tools are required. The bending performance of four T-head Square-neck One-side Bolted Connections (TSOBCs) for a beam to a HSSC and a Standard Double-sides Bolted Connection (SDBC) for comparison was experimentally studied, in which two arrangement patterns for the slotted bolt holes and two strengthening measures of stiffeners on the endplate and inner concrete in the HSSC was explored. The results show that the TSOBC with vertical bolt holes has nearly the same yield moment, and the horizontal bolt holes have more excellent post-yield performance, compared with the SDBC. Besides, three yield line patterns and an analytical model for calculating the bending bearing capacity of the HSSC and the concrete strengthened HSSC are proposed, respectively. • Tests on beam-to-column connections using TSOBs under bending were conducted. • TSOBCs have no less than 85% of the bending moment capacity of the traditional SDBCs. • Three novel yield line patterns of tube column wall were proposed. • A novel bending moment capacity calculation model of CFST column was presented. • Design methods of TSOBC were recommended.

Discussion on the optimal spacing of water curtain holes in cavern reservoir

Vertical and horizontal water curtain holes can be effectively used to seal underground oil storage caverns. However, the density of hole spacing affects the water sealing effect of the water curtain system. Based on the basic theory of Darcy’s law, this study established a three-dimensional model involving a main oil storage cavern, water curtain tunnel, water curtain hole, and surrounding rock mass. Different seepage effects on water curtain holes under different spacing are calculated and analyzed using a numerical analysis method. The optimal water curtain hole layout is finally determined by comparing the recommended spacing with the minimum water head difference.

Near-Infrared Photoresponse in Ge/Si Quantum Dots Enhanced by Photon-Trapping Hole Arrays.

Group-IV photonic devices that contain Si and Ge are very attractive due to their compatibility with integrated silicon photonics platforms. Despite the recent progress in fabrication of Ge/Si quantum dot (QD) photodetectors, their low quantum efficiency still remains a major challenge and different approaches to improve the QD photoresponse are under investigation. In this paper, we report on the fabrication and optical characterization of Ge/Si QD pin photodiodes integrated with photon-trapping microstructures for near-infrared photodetection. The photon traps represent vertical holes having 2D periodicity with a feature size of about 1 μm on the diode surface, which significantly increase the normal incidence light absorption of Ge/Si QDs due to generation of lateral optical modes in the wide telecommunication wavelength range. For a hole array periodicity of 1700 nm and hole diameter of 1130 nm, the responsivity of the photon-trapping device is found to be enhanced by about 25 times at μm and by 34 times at μm relative to a bare detector without holes. These results make the micro/nanohole Ge/Si QD photodiodes promising to cover the operation wavelength range from the telecom O-band (1260–1360 nm) up to the L-band (1565–1625 nm).

Asymmetric extent of distortion measured using the Watzke-Allen Test in patients with macular hole

Visual dysfunction in patients with macular hole is believed to occur because of cone cell displacement, often measured by the Watzke-Allen test (WAT). However, it is unknown if the horizontal and vertical measurements recorded by WAT reflect the true extent of photoreceptor displacement. This study aimed to measure the extent of photoreceptor displacement in patients with macular hole using WAT and compare the displacement value with the hole diameter measured by optical coherence tomography (OCT). This prospective, observational study at a single tertiary referral center included 43 patients with macular hole. WAT thresholds were assessed for their ability to detect macular hole. The slit was presented vertically and horizontally, and the brightness of the monitor screen was 180 cd/m2. Horizontal and vertical WAT thresholds for distortion were measured. Correlations and performance evaluations were assessed by Pearson's correlation analysis and Wilcoxon rank-sum test, respectively, between WAT threshold values and hole diameters. Horizontal and vertical WAT thresholds and diameters were compared using paired t-tests. The mean vertical WAT threshold (1.95° ± 0.87°) was significantly higher than the mean horizontal threshold (1.71° ± 0.73°; P < 0.0001). The mean minimum horizontal hole diameter (303.42 ± 111.16 mm; visual angle, 1.01°) was significantly greater than the mean minimum vertical diameter (264.12 ± 107.88 mm; visual angle, 0.88°; P = 0.0149). The minimum vertical and horizontal macular hole diameters were positively correlated with the vertical and horizontal WAT threshold values (r = 0.514, P < 0.01; r = 0.447, P < 0.01, respectively). The WAT threshold values were greater than the respective minimum macular hole diameters, indicative of cone cells displacement over an area larger than that of the hole. The difference in the extent of vertical and horizontal distortions suggests asymmetric hole formation. Hence, WAT threshold values may help evaluate visual function in patients with macular hole.

Dynamic response mechanism of a rock-filling interfacial coupling body to blasting in it

The interfacial coupling structure between the backfill and ore rock body in the filling mining method will be continuously disturbed by the influence of mining and blasting. In the filling-rock interfacial coupling, it is easy to produce the behaviors of debonding and fissure expansion, which will bring potential safety hazards to underground production. Because the field experiment is time-consuming and laborious, and it is difficult to observe the impact effect and the rock crack propagation process when the explosive is detonated, the simulation method was adopted for research. In the simulation, reasonable simplification is particularly important. According to the actual situation of blasting hole layout, the three rows of blasting holes that were detonated at one time were simplified into a single-row blasting hole model and an edge blasting hole model. According to the research results in related literatures, the coupling surfaces of the filling bodies and the ore rocks were simplified into three kinds (a flat interface, wavy interface and serrated interface). The three different shapes of the interfaces correspond to the different roughnesses of the interfaces, respectively. By considering that the hole arrangement method used in stope blasting is vertical hole arrangement, the holes are parallel, and at the same time, in order to improve the calculation of the software efficiency, simplified the three-dimensional model of the stope into a two-dimensional plane model. After a series of simplifications, a physical model for the filling-rock interface coupling body was proposed, and the corresponding geometric analysis model was established by using the ANSYS/LS-DYNA software And different material parameters were assigned to the different parts of the model, and the blasting effect was analyzed by software calculation. The mechanical influence of the interface coupling body structure was obtained, and the response law of different interface roughness, the curing age of the filling body and the blasting method on the blasting shock was obtained, and the mechanism of the blasting dynamics was discussed. The research results can reveal mechanical behaviors such as debonding and crack propagation at the coupling of filling-rock interface, and clarify the influence of different factors on the law of blasting shock response and the mechanism of blasting dynamics, which has certain guiding significance for downhole safety production. The results show as follows. (1) The blasting impact has three mechanical effects in the interface coupling body: tension, pressure and shear. When the stress wave passes through the interface, the peak acceleration of the monitoring point at the interface will increase due to different degrees of refraction. After passing through the coupling interface, the stress wave energy decays rapidly. (2) The impact of different interface roughness on blasting action is different. The joint roughness coefficient (JRC) represents the roughness of the interface coupling body. With the increase of the JRC value, the interface stress tends to rise first and then decline, but the overall damage decreases. (3) As the curing time of the backfill increases, the fracture range at the coupling interface shrinks, and the interface damage gradually changes from tensile damage to shear damage. (4) The damage of different detonation modes to the interface coupling body is different, and the damage of simultaneous detonation to the coupling interface is weaker than that of hole-by-hole detonation.

Cyclic behavior of T-stub connection to hollow section steel column using TSOBs

The One-side bolts are widely used in the connection of the closed section members in the prefabricated buildings. As a novel type of one-side bolt, T-head Square-neck One-side Bolt has the advantages of the simple structure, the convenient installation, and no need for special installation tools. In this paper, the sub-model for the tension region of the T-stub bolted beam-column connection was selected as the research object, and the cyclic test was conducted on four T-head Square-neck One-side Bolted Connections (TSOBCs) for T-stub to Hollow Section Steel Column (HSSC) and two Traditional High-strength Bolted Connections (THBCs) for comparison. The results of the test including the failure modes, the applied force-displacement hysteretic curves, the applied force-displacement envelope curves, the deformation capacity and ductility, the strength degradation, the stiffness degradation, the energy dissipation, and the strain evolution are discussed and analyzed in this paper. The experimental results denote that: (1) There are two failure modes in the test, mode i, HSSC wall yielding and mode ii, T-stub flange yielding; (2) The initial stiffness and peak bearing capacity of the TSOBCs decreased by 2.5% ~ 35.6% and 21.7% ~ 39.4%, respectively, compared with those of the THBCs; (3) When the failure mode ii occurred, the ductility and the equivalent damping coefficient of the TSOBC with vertical mounting holes are 42.5% and 5.4% higher than those of the THBC, respectively. Besides, the plastic deformation, rigid displacement, and bolt offset in the TSOBCs are analyzed using finite element models.

Design and application of Baihui moxibustion box

On the base of the principle of penetrating moxibustion and in combination with free adjustment devices such as movable U-shaped moxa stick holder and movable clamp, a new type of moxibustion box exerted on the head is designed, with precise positioning and sufficient heat intensity. Baihui moxibustion box is composed of two sections, i.e. body section and pillow section, which is as one structure. There are several vertical bar-shaped holes distributed evenly on the movable door outside moxa box. The U-shaped moxa stick holder on the inner side of the bar-shaped hole is connected with the fixed clamp on the outside, which is movable up and down, forward and backward for height adjustment. Such moxibustion box is characterized as accurate positioning, energy saving, temperature control and manpower saving.

Recombination rate analysis in long minority carrier lifetime mid-wave infrared InGaAs/InAsSb superlattices

Gallium is incorporated into the strain-balanced In(Ga)As/InAsSb superlattice system to achieve the same mid-wave infrared cutoff tunability as conventional Ga-free InAs/InAsSb type-II superlattices, but with an additional degree of design freedom to enable optimization of absorption and transport properties. Time-resolved photoluminescence measurements of InGaAs/InAsSb superlattice characterization- and doped device structures are reported from 77 to 300 K and compared to InAs/InAsSb. The low-injection photoluminescence decay yields the minority carrier lifetime, which is analyzed with a recombination rate model, enabling the determination of the temperature-dependent Shockley–Read–Hall, radiative, and Auger recombination lifetimes and extraction of defect energy levels and capture cross section defect concentration products. The Shockley–Read–Hall-limited lifetime of undoped InGaAs/InAsSb is marginally reduced from 2.3 to 1.4 μs due to the inclusion of Ga; however, given that Ga improves the vertical hole mobility by a factor of &amp;gt;10×, a diffusion-limited InGaAs/InAsSb superlattice nBn could expect a lower bound of 2.5× improvement in diffusion length with significant impact on photodetector quantum efficiency and radiation hardness. At temperatures below 120 K, the doped device structures are Shockley–Read–Hall limited at 0.5 μs, which shows promise for detector applications.

Perfusable host microfluidic endothelial networks for quantitative assessment of the effects of interstitial flows, macrophage polarization and monoclonal‐based immunotherapy on immune cell infiltration into a tumor spheroid

Monoclonal antibody-based immunotherapy is a promising treatment for several diseases such as cancer and virus infection. However, due to its highly selective target, drug testing using animal models or classical 2D human cell cultures are not sufficient to predict the drug effects on patients. New 3D organotypic models that employ 3D cell culture of human cells within a microfluidic device allow detailed characterization of critical biological interactions. In this project, we describe a new 3D cell culture model that allows the creation of in-vitro human perfusable vasculature containing hollow spaces for the insertion of tumor spheroids. A polydimethylsiloxane device with several vertical holes on top of the gel channel is used to create the host microvascular endothelial (HOME) network (Fig.1A). Endothelial cells and fibroblasts create perfusable vascular networks (Fig. 1B). Tumor spheroids are formed by coculturing MDA-MB-468 tumor cells (T), fibroblasts (F), and non-polarized (M0) or M2 macrophages, and denoted by TFM0 and TFM2 respectively (Fig. 1C). One day after inserting a tumor spheroid in collagen into the HOME networks through the hole, freshly-isolated monocytes are perfused into the vascular networks by luminal flows. We observe that after 2 days, the majority of monocytes remain either within the vasculature or extravasated but stay inside the fibrin gel outside of the hole containing the tumor spheroid (Fig. 1Di). On day 2, interstitial flows from the tumor spheroid cause monocyte migration from the vascular network side into the hole containing the tumor spheroid (figure 1Dii). When a TFM2 spheroid is inserted into the HOME networks, it recruits more monocytes than the TFM0 spheroid (Fig. Ei and Eii). Recruitment % is the percentage of monocytes that leave the blood vessel and migrate into the hole among the total number of monocytes in 3mmx3mm region of interest around the hole. Monocytes are recruited better by the TFM2 spheroid than the TFM0 spheroid (Fig. 1Gi). These results showed that interstitial flows from the tumor spheroid to the vascular networks and macrophage polarization are essential for monocyte recruitment. Multi-specific antibody UniTI102 developed by Elstar Therapeutics (MA, USA) neutralizes chemokine CCL2 to block monocyte recruitment. To characterize the response to the drug UniTI102, we compared devices having a TFM0 spheroid that are untreated (Fig. 1D) or treated with UniTI102 (Fig. 1F) and observed that less monocytes has migrated into the hole in the presence of UniTI102 at 100nM. Quantitative data also showed that less monocytes are recruited when devices are treated with 100nM UniTI102 than 100nM IgG (Fig. 1Gii).

Electrical resistivity methods to characterize the moisture content in Brazilian sanitary landfill.

The moisture content of the municipal solid waste (MSW) is a physical characteristic that plays a fundamental role in the stability and settlement of landfills. However, this physical index is difficult to monitor within the mass of landfilled MSW because it undergoes great variation due, mainly, to the heterogeneity and biodegradation of the waste. Brazilian MSW generally has a large amount of organic matter, that when biodegraded, generates a considerable volume of gases and fluids, aggravated by climatic conditions, such as high rainfall and temperatures. Hence, the importance of obtaining and evaluating the distribution of moisture content in the MSW mass over time. Currently, the electrical resistivity properties have been presented as an interesting approach to obtain the moisture content in landfills indirectly. This study aimed to apply geoelectrical methods as a tool to obtain and evaluate the moisture content distribution in an experimental cell of a sanitary landfill using Archie's law, which correlates the volumetric moisture content and electrical resistivity. Moisture content values were obtained in laboratory tests with MSW samples collected in two vertical holes and electrical resistivity measurements by means of vertical electrical sounding. The moisture content and the resistivity values of the samples were used to calculate the parameters a and m of Archie's law. This allowed to convert the resistivity tomography to moisture content tomography. The good correlation achieved between the moisture content calculated by Archie's law and that obtained from samples indicates that the use of electrical resistivity methods is useful to assess and monitor quantitativelythe moisture content in landfills using Archie's law.

Non-linear regression approach to ROP predicted in Geothermal well aerated-drilling at Field X, South Sumatera, Indonesia

Rate of penetration is one of the most significant drilling parameters for optimizing the cost of drilling geothermal wells. Many drilling variables affect the rate of penetration. Several correlations have been introduced to predict rate of penetration by involving some of the variables. In this study, a new empirical correlation based on an optimized nonlinear regression model was developed to predict ROP. Several drilling variables i.e. weight on bit, rotation-per minute, compressed air flowrate, true vertical depth, hole diameter, and foam flowrate were included into the correlation. SPSS (Statistical Product and Service Solutions) Software was applied to generate eight equations. The most appropriate equation was selected by comparing the calculated and measured ROP. The selected equation has average percentage difference of 14.6%. In addition, the procedure can be applied to estimate the effect of drilling variables on the accuracy of the model.

Influence of polypropylene beads and sodium carbonate treated nanosilica in water-based muds for cuttings transport

The drilling for hydrocarbons from oil and gas wells requires efficient drilling fluid and cutting-edge drilling technology. Furthermore, the removal of rock cuttings from oil and gas wells while drilling is a vital task of the drilling fluid, particularly in large-angle wells and long-range drillings. The rock cuttings if not transported to the surface effectively can result in severe costly drilling problems of drag and torque, pipe sticking, faster bit damage, etc. This research suggests a new method that applies polypropylene beads (PP) and silica nanoparticle (NS) treated by sodium carbonate (Na2CO3) to enhance the cuttings transport efficiency (CTE) of water-based mud (WBM). Tests were carried out in laboratory-scale cuttings lifting rig simulator equipped with a 20-ft. Long annulus, a 2.75-in. ID outer acrylic pipe, and an inner drill pipe of 1.05-in. OD. Six different 10 ppg weighted mud samples were formulated and coded mud nos. 1–6 using PP beads and Na2CO3 treated NS concentrations. Four cuttings sizes in the range between 0.4 and 4.0 mm at various hole angles (0°, 30°, 60°, and 90°) without pipe rotation were evaluated using a constant flow rate of 5.13 L/s. The results of rheological characterization using Herschel-Buckley model showed that all the mud systems are shear-thinning as the flow behaviour index ranged between 0.50 and 0.60. The fluid consistency parameter of the WBM indicates that the addition of PP beads and NS concentrations decreases the viscosity of the WBM. Also, the viscosity, yield point, gel strength, and filtration parameters of the WBM were decreased when the PP beads and NS concentrations were introduced before and after thermal aging experiments. This interprets the thinning nature of the mud systems. However, when these products were applied to lift cuttings to the surface, the lifted cuttings increased. The optimum mud system using Bingham plastic expression was found at mud no. 6 (BM-PP8-NS1) containing apparent viscosity of 30.5 cP at a shear rate of 1022 s⁻1, plastic viscosity of 13 cP and a yield point of 35 lb/100 ft2 at 78 °F. Cuttings size and hole angles seem to wield significant influence on CTE as the smallest cuttings (0.4–1.4 mm) were easier to be lifted in the vertical hole (0° angle), while the largest ones (2.8–4.0 mm) were the most lifted in the horizontal section (90° angle). The findings of this study can help for a better understanding of the mud performance of PP beads and Na2CO3 dispersed NS mixture for cuttings transport in a wellbore.

Improved Delivery of Remedial Agents Using Surface Foam Spraying with Vertical Holes into Unsaturated Diesel-Contaminated Soil for Total Petroleum Hydrocarbon Removal

Surface foam spraying technologies, employing natural infiltration processes, have recently been suggested to not disturb or mix contaminated soils. However, effective delivery of reactive remedial agents to the bottom area of a contaminated region using only natural infiltration processes can be a challenge. This study aimed to improve the delivery of remedial agents such as oxidants, microorganisms, and nutrients to all depths of 30 cm thick unsaturated diesel-contaminated soil using small vertical soil holes. Three vertical holes, occupying 0.8% of the total soil volume and 3% of the soil surface area, were made inside the 17.3 kg soil column. Persulfate oxidation foam and subsequent bioaugmentation foam spraying were applied for remediation of contaminated soil. Foam spraying with vertical soil holes improved the uniformity of distribution of remedial agents throughout the soil, as evidenced by the uniform pH, higher volumetric soil water content, and a microbial population of &gt;107 CFU/g. Therefore, the total petroleum hydrocarbon (TPH) removal efficiency (88–90%) from bottom soils was enhanced compared to soil columns without holes (72–73%) and the control test (5–9%). The kinetic study revealed that relatively similar TPH biodegradation rates (0.054–0.057 d−1) can be obtained for all soil depths by using this new and simple approach.

Numerical Study of Stability and Connectivity of Vertical Goaf Drainage Holes

During underground longwall coal extraction, overburden strata deformation may result in vertical goaf drainage holes, which are drilled in advance of mining for tail gate gas management, to fail. The performance of these vertical goaf drainage holes is controlled by mine design parameters and local geomechanical properties. This paper investigates the use of advanced 3D finite element modelling and 2D discrete element modelling simulation techniques to understand the fundamentals of vertical goaf drainage hole failure mechanism due to strata shear at a currently operating gassy Australian mine site. Finite element modelling is used to investigate the location of high shear in the overburden strata at the vertical goaf gas drainage hole region during longwall mining and the discrete element modelling is used to examine connectivity from the goaf region to the goaf-gas drainage system.

Research on the Impact of Different Force Directions on the Mechanical Properties and Damage Evolution Law of Sandstone with Different Hole Diameters

In this research, a uniaxial acoustic emission experiment was conducted on rock samples with different positions and diameters of the hole, and an analysis was made on the impact of different hole positions and diameters on the mechanical properties, failure, energy conversion, and acoustic emission‐caused damage characteristics and laws of the rock samples. The results reveal as follows: first, due to the existence of holes in rocks, the stress‐strain curve changes at each stage, accompanied by multiple stress drops. And the peak strength gradually reduces with the increase in hole diameter. At different hole positions, the duration that the rock sample passes through at each stage of the stress‐strain curve varies, and the peak strength of the rock with the vertical hole is greater than that of the rock with the horizontal hole. This indicates that the bearing capacity and stability of the rock sample with the vertical hole are greater than those of the rock sample with the horizontal hole of the same diameter. Second, by making a comparison on the failure characteristics of rock samples, it is found that the intact rock shows brittle failure. For the rock sample with the horizontal hole, symmetrical tensile cracks initially appear in the upper and lower parts of the hole and finally form shear failure. As for the rock sample with the vertical hole, Y‐shape failure originally presents and eventually forms N‐shape failure with the increase in hole diameter. Over a comparison with the failure pattern of an intact rock sample, it is demonstrated that the final failure pattern and crack expansion trend on the rock sample vary with the change in the hole position and diameter. Third, as obtained by comparing and analyzing the energy conversion of the rock with different diameters of the hole, the energy conversion in the rock is changed due to the existence of holes, and the increase in hole diameter causes a gradual decrease in the elastic energy stored in the rock and gradual increase in the dissipated energy. And by comparing the energy conversion of the rock with different positions of the hole, it is acquired that the elastic energy conversion ratio of the rock with the vertical hole is higher than that of the rock with the horizontal hole. Furthermore, an explanation was made on the difference in the failure processes of the two types of rocks from the perspective of energy conversion.

Study on Extraction of Cold Air through a Vertical Hole from a Large Snow Mound ― Introduction of experimental formula of αF value and separation of αF value into α and F ―

Study on Extraction of Cold Air through a Vertical Hole from a Large Snow Mound ― Introduction of experimental formula of αF value and separation of αF value into α and F ―