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Borehole breakout is a natural phenomenon in boreholes drilled in rock due to the induced stress concentration. Many researchers have attempted to correlate this phenomenon with in situ stress magnitudes. In this paper, a series of true triaxial tests on sandstone blocks (120 × 120 × 120 mm3) with different diameter pre-drilled holes have been carried out. Results confirmed that breakout geometries (angular span and depth) are dependent on the relative stress magnitudes. It is also noticed that a larger hole size (hole radius) yielded a wider angular span and deeper normalised depth (breakout depth/hole size), which indicates that hole size is an important parameter for breakout geometries. In addition, the analysis on previous experimental studies suggested that the relationship between two breakout geometries is not unique and is heavily influenced by the horizontal stress magnitudes. The analysis of the existing model also revealed the angular span may be narrowed with increasing horizontal stress ratio under a certain stress–strength condition. Both analyses indicate the breakout geometries are not only dependent on each other but also on the horizontal stress magnitudes. This leads to a tentative conclusion that breakout geometries may not be redundant factors and might be used for horizontal stress estimation.

Purpose/objective We propose a novel lattice deployment for spatially fractionated radiotherapy (SFRT) treatments. In this approach, a larger diameter high‐dose sphere is centrally placed in the bulky tumor mass and surrounded by smaller diameter high‐dose spheres. Materials/methods Thirty SFRT patients (10 head and neck [HN], 10 abdominal/pelvis, and 10 chest/lung cases) treated with an MLC‐based crossfire method were retrospectively analyzed. Eleven differential hole‐size lattice patterns were benchmarked against the clinically delivered SFRT plans (1 cm diameter cylinders, 2 cm spacing) and the standard uniform lattice pattern (1.5 cm diameter spheres, 3 cm spacing). These patterns varied in core diameter (C: 2–4 cm), spacing (S: 2–4 cm), and peripheral diameter (P: 1–2 cm). In addition to peak‐to‐valley‐dose ratio (PVDR), tumor dose metrics (D50%, V50%, Dmean), Dmax to nearby critical organs, and ablative dose (V75%/V50% and V15Gy) were evaluated. Results 10 out of 11 differential hole‐size patterns showed increases in D50%, Dmean, and V50% compared to the standard lattice pattern. One pattern (C = 3 cm, S = 2 cm, P = 1.5 cm) outperformed the clinical SFRT plans in D50% (Δ = 1.8 Gy, p = 0.003; Δ = 2.0 Gy, p = 0.015; Δ = 0.9 Gy, p = 0.045), Dmean (Δ = 1.6 Gy, p = 0.003; Δ = 1.7 Gy, p = 0.021; Δ = 0.7 Gy, p = 0.042), and V50% (Δ = 20.4%, p < 0.001; Δ = 16.6%, p = 0.008; Δ = 10.3%, p = 0.079) for the HN, abdominal/pelvis, and chest/lung SFRT patients, respectively. This pattern also demonstrated average increases to D5% D10%, D90% across all 30 patients compared to both benchmarked patterns. However, this pattern showed reduced PVDR compared to the clinical and standard SFRT plans but still achieved a ratio > 3.0. All differential hole‐size patterns demonstrated decreases in Dmax to critical organs compared to the clinical SFRT plans. Moreover, compared to the clinical SFRT and the standard lattice plans, 9 out of 11 differential hole‐size patterns demonstrated increases in V75%/V50% and V15Gy. Conclusion All differential hole‐size SFRT replans were clinically acceptable, with C = 3 cm, S = 2 cm, and P = 1.5 cm providing the optimal setting for select tumors. Differential lattice patterns enhanced the ablative dose to the bulky tumors while restricting the maximum dose to adjacent critical organs.

Owing to the excellent integrated structure, notch-insensitivity, delamination-free characteristics, 3D braided composites have a broad range of engineering applications. In this paper, the notch size effects on two types of 3D braided composites were experimentally examined. Style I incorporated 40% of longitudinal lay-in yarns. Style II was the pure braids. The Point Stress Criterion (PSC) was applied to predict the open-hole strength of 3D braided composites. It is found the 3D braided composites can keep higher proportion residual strength after involving the different circular hole sizes compared to plain woven laminates. The open-hole pure braided specimen shows better performance than that the braids with longitudinal yarns, the lay-in longitudinal yarns improve neither specimens’ un-notched strength, nor the modulus. The predicted open-hole strength were compared with experimental results. The traditional analytical method can predict the open-hole strength of 3D braided composite to some extent. Under uniaxial tensile stress, the failure behaviour of two types of 3D braided specimens are different. For un-notched specimen, clear cracks usually show up on the Style II specimen, while it is not true for Style I coupon. For notched specimen, the crack of both notched specimens will propagate along the notch and finally render the specimen to fail

An integrated circuit for a physical unclonable function (PUF) to generate an identifier for each device is proposed based on the via formation probability. The via hole size is determined to be smaller than that specified by the design rule which guarantees successful via formation. As a result, a via is formed with a certain probability. A proper via hole size and a post-processing method are found to obtain very high randomness in the bit sequences, and it is confirmed that the bit error rate is zero through repeated measurements over one year under the supply voltage variations with noises and in a wide range of temperature. This time invariance of bits can be attributed to the fact that the via formation does not change over time, once they are formed.

Recently, clothing development 3D printing and the evaluation of its physical characteristics have been explored. However, few studies have tackled thermal comfort, which is a major contributor to the wearers’ comfort. Therefore, this study was designed to suggest effective materials and hole sizes for clothing obtained by 3D printing to maintain a comfortable clothing environment. In particular, two main variables, namely five different materials and three-hole sizes, were analyzed. All samples were placed on a hot plate (36 °C), and their surface temperature and humidity were measured for 10 min. The samples with only thermoplastic polyurethane (TPU) achieved the largest temperature change of 3.2~4.8 °C, whereas those with ethylene-vinyl acetate (EVA) foam exhibited the lowest temperature change of −0.1~2.0 °C. Similarly, the samples with only TPU showed the greatest humidity change of −0.7~−5.5%RH. Moreover, the hole size had a larger effect on humidity change than material type. The samples with large holes achieved the largest humidity change of −4.4%RH, whereas the samples without holes had the smallest humidity change of −1.5%RH after 10 min (p < 0.001). Based on these results, various combinations of materials and hole sizes should be considered to fit the purpose of 3D printing clothing.

Recently, a novel 4 D Einstein–Gauss–Bonnet gravity was formulated by Glavan and Lin (Phys Rev Lett 124(8):081301, 2020). Although whether the theory is well defined is currently debatable, the spherically symmetric black hole solution is still meaningful and worthy of study. In this paper, we study the geodesic motions in the spacetime of the spherically symmetric black hole solution. First of all, we find that a negative GB coupling constant is allowable, as in which case the singular behavior of the black hole can be hidden inside the event horizon. Then we calculate the innermost stable circular orbits for massive particles, which turn out to be monotonic decreasing functions of the GB coupling constant. Furthermore, we study the unstable photon sphere and shadow of the black hole. It is interesting to find that the proposed universal bounds on black hole size in Lu and Lyu (Phys Rev D 101(4):044059, 2020) recently can be broken when the GB coupling constant takes a negative value.

Based on the finite element simulation and the experimental verification, the stiffness of container building with holes is studied. Firstly, through finite element software of the Abaqus, 20ft and 40ft container model are established, and the corresponding holes and stiffening members are considered. Through simulation, the stiffness and Mises stress contour of the container model are got. Secondly, a full size experiment of container with holes is studied, and then, through comparison of the loading-displacement curves and the loading-stress curves with finite element simulation, the finite element model is verified. Finally, based on the verified finite element model, the influence laws of the hole and the stiffening member is given, and the relevant design recommendations of the hole position, the hole area, the hole size ratio and the stiffening member form are given. Research results make feasible in design and construction of the container buildings and provide some references to the corresponding specification preparation.

In order to promote the development of miniaturization, low-energy and integration of exploding foil initiator, its low-energy design, preparation and tests were studied. It is expected to control the initiation voltage less than 1000 V. Based on the mechanism of bridge electrical explosion and driving flyer, the performance of exploding foil initiator at different parameters of bridge, flyer and barrel was calculated, which indicates an optimal matching relationship among component parameters as the bridge size of 0.2×0.2×0.006 mm, the flyer thickness of 12~22 μm and the barrel hole size of Ф 0.3×200~350 μm.

Cultivation of the golden teak (Tectona grandis L.) requires the planting hole size and appropriate use of manure. The size of planting hole provides plant growth, so that the plant can grow with optimum and appropriate use of manure to provide nutrients for the plants. . The aims of the study was to obtain an interaction between planting hole size and manure on vegetative growth phase of golden teak. Treatments tested in this study were with 4 treatment of planting hole size as the first factor and 3 levels of manure as the second factor. The twelve treatments were arranged in a factorial randomized block desiagn with three replicates. Variable measured plant height, number of leaves, and the flush changes to mature. The results showed that there were no interactions between the planting hole size and goat manure on early vegetative growth of golden teak plants. The planting hole size treatment showed significant effects on some variables height of plant, number of leaves and flush change to mature leaves. Manure treatment showed no significant effect for all variables. The observation variables that showed no significant differences height of plant, number of leaves and flush change to mature leaves.

Firstly, the damaging effect of the internal explosion in a closed cabin by numerical simulation has been evaluated, which indicates that the pressure peak of the shock wave and the duration of positive pressure in the closed cabin has been increased at a large scale compared with the free field, and the corner-structures of the cabin have been damaged seriously under the shock wave at the same time. Then the explosion response effect of the hull superstructure which has an explosion venting hole has been analysed, and the pressure peak of the shock wave in a different location and the superstructure which has a different explosion venting hole size has been compared, which shows that the explosion venting holes have a strong impact on cabin explosion shock wave propagation, the scope and ratio of the venting explosion depend linearly on the characteristic length of explosion venting holes, and the explosion venting holes can protect the cabin corner structure within certain TNT limits. It is concluded that setting a reasonable size and proper location of the explosion venting holes can achieve the purpose of protecting the important compartments.