Expansion Of Cavity Research Articles

Effects of axial launch spacing on cavitation interference and load characteristics during underwater salvo

This paper analyzes the effect of launch interval on cavitation flow interference and load characteristics during underwater salvo. The study employs the Improved Delayed Detached Eddy Simulation and the Schnerr-Sauer cavitation model, Volume of Fluid (VOF) multiphase flow model, and overlapping grid. Additionally, decompression experiment systems are designed, and numerical simulations are found to be in good agreement with experimental results, thus verifying the effectiveness of the simulation. Detailed discussions are provided on multiphase flow field and load distribution. The results reveal a top-down collapse process of the cavity, with collapse shrinking to an isolated bubble at the end. Synchronized collapse pressure is characterized by short pulse widths at the peaks, all located at the lowermost part of the cavity. During the underwater stage, when the axial launch spacing ranges between 0.5 times and 1.0 times the length of the projectile, the head of the second projectile acts on the area below the center of mass of the first. This leads to gradual stabilization of the initial cavity and a decrease in deviation of the center of mass toward the inside. Despite experiencing large-scale fracture and detachment due to interference from the wake of the first engine, the motion stability of the inside cavity of the second projectile remains intact. In the water exit stage, when the axial launch spacing ranges between 0.75 times and 1 time the length of the projectile, it causes expansion and contraction of the inside cavity of the second projectile. However, asymmetric synchronous collapse loads may occur, leading to unstable motion posture.

A novel Ta-contained TiAl alloy with excellent high temperature performance designed for powder hot isostatic pressing

TiAl alloys offer strong potential for replacing conventional nickel-base alloys in structural applications at high temperatures, which requires good high temperature performance. This study analyzes the creep performance and thermal exposure characteristics for a powder hot isostatic pressing (P-HIP) Ta-contained TiAl alloy. The microstructure characteristics, creep performance, and thermal exposure properties of the nearly lamellar (NL) alloy with a size of about 145 μm were investigated. The alloy remains 0.72 % fracture strain at room temperature after exposure at 750 ℃ for 1000 h. The fitting results of creep curves show that the creep stress index n is 15.82 at 750 ℃, indicating the power law creep mechanism. By reducing the interfacial energy, Ta can facilitate the formation of metastable structures and achieve refinement. The enrichment of Ta element at the lamellar edge, both observed after thermal exposure and creep, inhibits the growth of lamellae and hinders the expansion of cavities due to its low diffusion rate, improving the thermal stabilities and creep performance. The P-HIP Ta-contained TiAl alloy shows exciting high temperature performance.

Development of a New Swine Model Resembling Human Empty Nose Syndrome.

Background and Objectives: Empty nose syndrome (ENS) is a debilitating condition that often results from traumatic or iatrogenic causes, such as nasal surgery. There are various conservative and surgical treatments for ENS, but their effectiveness remains uncertain. Therefore, the development of animal models that accurately mimic human ENS is essential for advancing effective treatment strategies. Materials and Methods: To investigate ENS development, turbinoplasty was performed in the nasal cavity of swine, entailing partial removal of the ventral turbinate using turbinectomy scissors followed by electrocauterization. After 56 days, samples were obtained for histological and morphological analyses. Results: A significant reduction in the volume of the ventral turbinate in the ENS model led to an expansion of the nasal cavity. Histological analysis revealed mucosal epithelial changes similar to those observed in ENS patients, including squamous cell metaplasia, goblet cell metaplasia, submucosal fibrosis, and glandular atrophy. Biomarkers related to these histopathological features were identified, and signals potentially contributing to squamous cell metaplasia were elucidated. Conclusions: The swine ENS model is anticipated to be instrumental in unraveling the pathogenesis of ENS and may also be useful for evaluating the effectiveness of various treatments for ENS.

Contraction and expansion of a cylindrical cavity in an elastoplastic medium: A dislocation‐based approach

AbstractThe contraction or expansion of a cylindrical cavity in an elastoplastic medium is usually analyzed from a continuum based approach with a plasticity constitutive model. However, localized deformations, which are rooted in the post‐failure softening response of geomaterials, are observed in the form of spiral‐shaped fractures in laboratory tests. An alternative approach based on dislocation theory is introduced in this paper for modeling cavity contraction or expansion. In this model, several equally spaced spiral‐shaped shear fractures initiate and propagate away from the cavity within the linearly elastic medium. The Mohr‐Coulomb criterion and a dilatancy rule are imposed on the shear fractures to constrain the stresses and the displacement jumps. The direction of fracture propagation is determined by minimizing plastic dissipation. The displacement discontinuity method is used to discretize the shear and normal displacement jumps along the fracture and solve the problem numerically. The calculated crack path follows a logarithmic‐like spiral, similar to the slip lines predicted by plasticity theory. The relationship between the pressure and radial displacement at the cavity boundary converge towards the classical elastoplastic solution as the number of fracture branches increases.

A novel coupled algorithm for Studying the performance characteristics of water ramjet in the flight of supercavitating vehicle

When a supercavitating vehicle performs a flight, the water ramjet of the vehicle exploits the water in the surrounding environment as an oxidiser and is inevitably affected by the vehicle motions. In this study, the characteristics of the performance change in a water ramjet were investigated when a supercavitating vehicle performs a flight to gain more insights into the design of underwater power systems. Given the principle of independent cross-section expansion of cavities, a longitudinal ventilated supercavity model was built to predict the development of a ventilated cavity and its interaction with the body. A thermal calculation model was developed based on the minimum free energy method to calculate the performance parameters of water ramjets. A novel coupling algorithm was proposed based on the aforementioned model to integrate the motion of a supercavitating vehicle with the operation of a water ramjet. The integration described above was achieved by linking the water intake and body motion and calculating the performance change characteristics of the water ramjet during the flight of the supercavitating vehicle. The operating characteristics of the water ramjet with changes in the designed water-fuel ratios were investigated to provide a basis for exploring the unperturbed flight of the vehicle, depth regulation, and underwater environmental changes. The thrust of the water ramjet is less affected by external factors, and its performance feedback tends to exacerbate external disturbances at a designed water-fuel ratio lower than the optimal water-fuel ratio. A water ramjet with a designed water-fuel ratio higher than the optimal water-fuel ratio has a rapid response time, adaptive thrust, and stable combustion chamber pressure. External disturbances slightly affected the thrust and combustion chamber pressure of the water ramjet when the designed water-fuel ratio was equal to the optimal water-fuel ratio. The results of this study provide technical support for optimising the design of water ramjet.

A Simplified Theoretical Method for Estimating the Effect of Capsule Grouting Expansion Technology on Controlling Pile Deformation

Deep excavation and shield tunneling processes often induce significant deformation in adjacent existing pile foundations, posing risks to the safety of superstructures. To address this issue, capsule grouting expansion technology has emerged as an efficient and economical technology to actively control pile deformation during such construction activities. This technology has been applied in some engineering projects aimed at safeguarding nearby buildings or facilities. However, theoretical research on capsule grouting expansion technology is limited and lags behind its practical engineering application. This paper proposed a simplified theoretical approach for estimating the effect of capsule grouting expansion technology on the deformation of neighboring pile foundations. Initially, virtual image technology was employed to obtain an analytical solution for the lateral displacement of soil resulting from the expansion of a cylindrical cavity with infinite height. The pile was considered as an Euler–Bernoulli beam on a Winkler foundation, allowing for the calculation of the loading response of the existing pile foundation. Utilizing the two-stage method, the theoretical analytical method of the lateral deformation of the pile shaft caused by capsule expansion was obtained. The reliability of the proposed theoretical method was verified by comparing the measured and calculated results. Further investigation into the controlling effect of the capsule grouting expansion technology on the deformation of the pile foundation was conducted through parametric analyses. These analyses encompass capsule radius, the distance between the capsule and pile foundation, the depth of the capsule, the length of the capsule, and the pile base constraints.

Expansion of a Spherical Cavity in an Infinite Dilatant Medium Obeying the Drucker–Prager Yield Criterion and a Non-Associated Plastic Flow Rule

Expansion of a Spherical Cavity in an Infinite Dilatant Medium Obeying the Drucker–Prager Yield Criterion and a Non-Associated Plastic Flow Rule

Failure evolution and mechanism of ground collapse due to exfiltration of shallowly buried water pipeline

Exfiltration of defective water pipelines is one of the leading causes contributing to the frequent ground collapses in congested urban areas; hence, revealing the failure evolution and mechanism of this hazard is essential to its prevention and mitigation. In this study, comprehensive experimental model tests were conducted first to characterize the evolution of soil erosion and ground collapse due to exfiltration of shallowly buried defective water pipes and examine the effects of six critical parameters, i.e., opening size and location, pipe pressure and buried depth, groundwater level, and exfiltration condition. Three failure behaviors of strata around leaking waterpipe were identified, i.e., minor disturbance (slight), formation and collapse of an erosion cavity (moderate), and soil fluidization (severe). Moreover, the ground loosening zone induced by cavity collapse could be roughly estimated using the modified flow ellipsoid theory; soil fluidization would occur once the ratio of water pressure head inside the pipe to its buried depth was greater than 2. Subsequently, a validated computational-fluid-dynamics and discrete-element-method (CFD–DEM) coupling method was employed to explore the microscopic mechanism of cavity erosion under the exfiltration flow. It was disclosed that the formation and expansion of a temporary cavity resulted from internal soil erosion, including the emigration of massive fine particles and aggregation of coarse particles around the defective pipe. Finally, the numerical simulation results indicated that cavity erosion would be exacerbated by increasing flow velocity and particle size-ratio, reducing soil fines content, and changing the opening from the pipe crown to its invert.

Similarity Solutions for Spherical Cavity Expansion in Strain-Softening Soils and its Application in Cone Penetration Test

The cavity expansion theory is commonly employed to predict the grouting pressure and cone penetration resistance. However, existing theoretical solutions for cohesive-frictional soils with dilation fail to simultaneously consider both the elastic deformation in the plastic zone and strain-softening behaviour of soils. To address this limitation, a similarity solution was derived for the expansion of spherical cavities from a zero initial radius with an initial confining pressure in strain-softening Mohr–Coulomb materials. The results demonstrate good agreement with previous theories, predicting an ultimate pressure higher than that obtained by neglecting elastic deformation in the plastic zone but lower than that calculated by neglecting softening characteristics. Moreover, several influential factors affecting the radius of the plastic zone and ultimate pressure were meticulously examined. On-site cone penetration test data and the theoretical results showed notable agreement. This indicates that the proposed solution exhibits a better conformance with the field data than do the previous solutions.

Expansion of a spherical cavity in an infinite porous rigid/plastic medium

An expanding spherical cavity of a zero initial radius surrounded by an infinite porous rigid/plastic medium is considered. The material is assumed to obey the flow theory of plasticity based on a yield criterion and its associated flow rule. The yield criterion depends on the linear and quadratic stress invariants. No restriction is imposed on this dependence, except for the standard requirements imposed on the yield criteria. It is shown that the solution can be extended into the rigid region. The yield criterion approaches the von Mises yield criterion as the relative density approaches unity. Some equations contain the expression 0/0 at the rigid/plastic boundary. In this respect, the present solution is qualitatively different from available elastic/plastic solutions. However, the solution does not provide the solution for the von Mises yield criterion as a particular case. Numerical results are presented for Green’s yield criterion. These results follow physical expectations concerning the distributions of the relative density, the radial velocity, and the radial stress. The solution is adapted for expanding a cavity of a non-zero initial radius. The pressure required for expanding the cavity is calculated.

A novel CFD-DEM-DPM modelling of fluid-particles-fines reacting flows

The complex fluid-particle-fine (FPf) reacting flows have been widely practised in many energy-intensive engineering processes, yet numerical methods capable of comprehensively describing the particle-scale thermochemical behaviours related to the FPf reacting flows were still lacking. In this work, a novel CFD-DEM-DPM model is developed, for the first time, to describe the fluid, particles and fines reacting flows and their interactions. Then, to demonstrate its effectiveness, it is employed to simulate the co-combustion of coke and pulverized coal in a dynamic raceway in ironmaking blast furnaces (BFs). After model validation, the complex in-furnace phenomena related to the co-combustion of coarse coke particles and fine coal particles are comprehensively captured. Particularly, instead of the pre-set raceway treatment in the previous raceway simulations, a dynamic raceway cavity is predicted explicitly driven by the fluid-particle-fine interactions and further, inside the dynamic raceway, the combustion of coal fines including moisture evaporation, devolatilization and char reactions are presented in detail. Subsequently, the impact of operations with and without coal injections are quantitatively compared, showing that both the reducing gas and reaction heat from the coal combustion contribute to an expansion of the raceway cavity. Further, the effects of pulverized coal rate on the in-furnace phenomena are studied. The present work represents a significant breakthrough in the explicit modelling of FPf reacting flows, and provides a cost-effective tool for understanding FPf-related processes and developing new technologies including carbon–neutral ironmaking technologies.

DESTRUCTION OF ROCKS BY EXPLOSION DURING OIL TRANSPORTATION

When oil and gas wells are ready for operation, when drilling is carried out at the bottom of the well to establish contact with the formation, it is considered that the degree of crushing of the rocks is proportional to the speed of application of the load. As a result of the stresses created by them, the degree of fragmentation is higher. In the article, it is proposed to take into account the quality of crushing of the necessary rock by using some empirical coefficients in the calculation formulas. The dynamics of the rock dispersion process is studied on the basis of the hydrodynamic hypothesis. Here, the solution of the system of differential equations is given based on the fundamental laws of conservation of mass, energy and momentum. Based on the strength properties of mountain rocks, broken lines are found in the continuum of the whole environment, which determines the final effect of rock crushing. However, the accepted assumptions about the incompressibility of the rock and the transfer of the explosive impulse to the immediate environment significantly reduce the practical value of the results. It should be noted that in the immediate area directly adjacent to the load, the mountain rock is under uneven volume compression. In this case, the largest tangential stresses occur mainly in planes oriented at an angle of 450 to the radial direction. Thanks to this, a system of spiral sliding lines breaks the rock into small blocks. Outside this zone, a system of radial cracks is formed as a result of the expansion of the massif. When the pressure in the gas cavity decreases and the mass moves back in the direction of the load, tangential cracks appear. The combination of the volume compression zone and the reach zone constitutes the controlled crushing area. When the compression wave reaches the bare surface, it becomes a stress wave. As this wave travels from the surface to the load, it forms a system of jump cracks. The high explosive effect of explosive gases with sufficient explosion energy causes the release of such shattered rock. Obviously, this concept is very important for the development of the theory of explosive disintegration of mountain rocks. Because there is no unequivocal relationship between the nature of the dissolution of the rock and the acoustic hardness. One of the first to clearly describe the mechanism of shock wave formation and its transformation into a more explosive and seismic wave when detonation reaches the boundary of the charge cavity. In rocks, shock waves are formed during the entire time of expansion of the gas cavity. It explains in detail the mechanism of cracking phenomena by considering the cracks as a source of multiple reflections of the stress wave. Keywords: rock strength, constant material, scale effect, rocks, destruction probability, fractured, robustness theory, microcrack, mineral, experience constant, density of defects, displacement, compression.

The changing morphology of the ventricular walls of mouse and human with increasing gestation.

That the highly trabeculated ventricular walls of the developing embryos transform to the arrangement during the fetal stages, when the mural architecture is dominated by the thickness of the compact myocardium, has been explained by the coalescence of trabeculations, often erroneously described as 'compaction'. Recent data, however, support differential rates of growth of the trabecular and compact layers as the major driver of change. Here, these processes were assessed quantitatively and visualized in standardized views. We used a larger dataset than has previously been available of mouse hearts, covering the period from embryonic day 10.5 to postnatal day 3, supported by images from human hearts. The volume of the trabecular layer increased throughout development, in contrast to what would be expected had there been 'compaction'. During the transition from embryonic to fetal life, the rapid growth of the compact layer diminished the proportion of trabeculations. Similarly, great expansion of the central cavity reduced the proportion of the total cavity made up of intertrabecular recesses. Illustrations of the hearts with the median value of left ventricular trabeculation confirm a pronounced growth of the compact wall, with prominence of the central cavity. This corresponds, in morphological terms, to a reduction in the extent of the trabecular layer. Similar observations were made in the human hearts. We conclude that it is a period of comparatively slow growth of the trabecular layer, rather than so-called compaction, that is the major determinant of the changing morphology of the ventricular walls of both mouse and human hearts.

Effect and mechanism of Yueju Pills on breast cancer induced by DMBA in rats

This paper aims to explore the inhibitory effect of Yueju Pills on breast cancer and decipher the underlying mechanism. A total of 92 SPF-grade SD female rats were involved in this study, and 14 of them were randomly selected into control group. The remaining 78 rats were administrated with 7,12-dimethylbenzanthracene(DMBA) by gavage to establish the breast cancer model. The modeled rats were randomized into model, tamoxifen(1.9 mg·kg~(-1)·d~(-1)), and low-and high-dose(17, 34 g·kg~(-1)·d~(-1)) Yueju Pills groups. The mental state, food intake, and activities of the rats were observed daily, and the body weight was measured on alternate days. After 12 weeks of administration, the rats were sacrificed and the tumor weight was measured. The serum estrogen and progeste-rone levels were determined by enzyme-linked immunosorbent assay. The histopathological changes of the breast and tumor were observed by hematoxylin-eosin staining. Western blot was employed to measure the protein levels of glucose transporter 1(GLUT1), lactate dehydrogenase A(LDHA), phosphofructokinase muscle(PFKM), pyruvate kinase isozyme type M2(PKM2), hexokinase 2(HK2), nuclear factor-kappaB(NF-κB), and phosphorylated NF-κB. The intestinal microbiome was examined by 16S rRNA high-throughput sequencing. The results showed that compared with the model group, high and low-dose Yueju Pills showed the tumor inhibition rate of 15.8% and 64.5%, respectively, and the low dose group had stronger inhibitory effect. Compared with the control group, the model group presented elevated the levels of estrogen and progesterone in serum. The administration of Yueju Pills lowered such ele-vation, and the low-dose group showed stronger lowering effect(P<0.05). Compared with the model group, Yueju Pills reduced the glands with increased breast tissue, the degree of breast duct expansion, the number and area of acinar cavity, the secretions, and the layers of mammary epithelial cells. Furthermore, Yueju Pills down-regulated the expression of GLUT1, LDHA, PFKM, PKM2, HK2, and NF-κB(P<0.05) and altered the diversity, composition, structure, and abundance of intestinal flora. The results showed that Yueju Pills could inhibit breast cancer by regulating the secretion of estrogen and progesterone, glycolysis, inflammatory cytokines, and intestinal flora.

Plane Strain Expansion of a Cylindrical Cavity in an Infinite Porous Rigid/Plastic Medium Obeying a General Yield Criterion

A semi-analytical plane-strain solution for an expanding cylindrical cavity surrounded by an infinite porous rigid/plastic medium is presented. The constitutive equations are a general yield criterion and its associated flow rule. The yield criterion depends on the relative density and the linear and quadratic stress invariants. No restriction is imposed on this dependence, except for the standard requirements imposed on the yield criteria. The boundary value problem reduces to a Cauchy problem for three ordinary differential equations. This system of equations must be solved numerically. Numerical results are presented for Green’s yield criterion. This yield criterion involves two functions of the relative density. The influence of the choice of these functions on the distributions of the relative density, the radial velocity, and the stress components is revealed.

Undrained expansion analyses of a cylindrical cavity in anisotropic sands incorporating the SANISAND model

AbstractSoils are known to be inherently anisotropic, resulting in complex responses to loading. This paper aims to develop an elastoplastic solution for the undrained expansion of a cylindrical cavity in sands adopting a non‐associated and anisotropic model, SANISAND. The rigorous derivation of the stress‐strain state of the soil element is provided following a standardized solving procedure. The dilatancy and crushing of the soil are invoked in the three‐dimensional cavity expansion solution by adopting the critical state soil mechanics and limiting compression curve, respectively. By combining this with a governing equation that considers the undrained condition, the stress‐strain state of the surrounding soil around the cavity can be determined. A subroutine is then implemented into the ABAQUS FEM simulation to verify the solution. The solutions are also validated against those based on an isotropic model, and anisotropic sand is used to investigate the effects of the initial effective mean stress, at‐rest coefficient of earth pressure, and overconsolidation ratio on the stress distribution, stress path, and boundary surfaces.

Differential Effects of Clotrimazole on X-Ray Crystal Structures of Human Cytochromes P450 3A5 and 3A4.

Cytochromes P450 CYP3A5 and CYP3A4 exhibit differential plasticity that underlies differences in drug metabolism and drug-drug interactions. To extend previous studies, CYP3A4 and CYP3A5 were cocrystallized with clotrimazole, a compact ligand that binds to the heme iron in the catalytic center of the active site. Binding studies indicate that clotrimazole exhibits tight binding to CYP3A5 with a binding affinity (Kd) of <0.01 μM like that of CYP3A4. A single clotrimazole is bound to the heme iron in CYP3A4 that triggers expansion of active site cavity that reflects a loss of aromatic interactions between phenylalanine sidechains in the distal active site and increased conformational entropy for the F-F' connector due to reorientation of Phe-304 to accommodate clotrimazole. In contrast to CYP3A4, the CYP3A5 Phe-304 exhibits an induced fit along with Phe-213 to form edge-to-face aromatic interactions with heme-bound clotrimazole. These aromatic interactions between aromatic amino acids propagate by induced fits with a second clotrimazole residing in the distal active site and a third clotrimazole bound in an expanded entrance channel as well as between the three clotrimazoles. The large, expanded entrance channel surrounded by the C-terminal loop and the F' and A' helices in CYP3A5 suggests conformational selection for the binding of clotrimazole due to its large girth, which may also cause the entrance channel to remain open after the binding of the first clotrimazole to the heme iron. The additional binding sites suggest a path for sequential binding of one molecule to reach and bind to the heme iron. SIGNIFICANCE STATEMENT: Clotrimazole binds to the heme iron of CYP3A5 and CYP3A4. In CYP3A5, two clotrimazoles also bind in the distal active site and in an expanded entrance channel. Aromatic interactions between clotrimazoles and phenylalanine sidechains including Phe-304 indicate induced fits for each clotrimazole. In contrast to CYP3A5, displacement of the CYP3A4 Phe-304 rotamer by clotrimazole leads to extensive disruption of phenylalanine interactions that limit the space above the heme, to an expanded active site cavity, and to increased CYP3A4 conformational heterogeneity.

Thermally Tunable Adsorption of Xenon in Crystalline Molecular Sorbent.

The thermostability of encapsulated xenon is investigated in a series of isostructural crystalline sorbents. These sorbents consist of metal-organic capsules, with the general formula of [ConFe4-nL6]4- (n = 1, 2, 3 and 4), where L2- is an organic linker with two sulfonate groups. In the crystalline sorbent, guanidinium cations form H-bond networks with the peripheral sulfonate groups in the solid state and trap xenon in the molecular cavities, which are at least 2.7 times the volume of xenon. When heated, the sorbent retains xenon up to 561 K, i.e., 396 K higher than the boiling point of xenon. Furthermore, the thermostability of trapped xenon can be modulated by varying the ratio of Co:Fe in the crystalline sorbent. Elemental analysis on a single crystal by energy dispersive X-ray spectroscopy confirms the homogeneous distribution of Co and Fe in the sorbent. Structural analyses reveal that the expansion of capsule cavity is proportional to the Co:Fe ratio, with increases of 0.049(1) Å and 6.4(8) Å3 in metal-metal distance and cavity volume, per substitution of Fe by Co center. Steric repulsion between peripheral sulfonate groups is found to render a hypothetical face-centered cubic structure of (C(NH2)3)4[Fe4L6] not accessible, which would have trapped xenon with exceptional thermostability. The stable and tunable trapping of xenon in crystalline sorbents by over-sized molecular cavities suggests a new strategy for separation and storage of xenon, through introduction of kinetic barriers, such as H-bond networks.

Theoretical determination of the expansion forces of the technological cavity in the soil by wedge-prismatic and conical-cylindrical working bodies

&#x0D; Problem. The article deals with the problem of expansion of the technological cavity in the soil (TPG), previously obtained by the method of controlled static piercing, for the laying of underground linear extension objects (LPO) of urban communication networks. Group laying of communications in one cavity requires large holes, which in turn leads to a significant increase in the workforce and dimensions of work equipment. The only way out of such a situation is the use of working bodies (RO) of wedge-prismatic form, gradual expansion of the hole in several stages and change of soil moisture in the walls of the hole cavity. Goal. The main goal is to create a methodology for engineering calculation of the parameters of the wedge-prismatic working bodies and to determine the static expansion efforts of the TPG based on the known initial data on the soil and the shape of the RO. Methodology. The study is based on the theory of the invariance of soil mass before and after piercing. In the process of expanding the TPG to the required size, the density of the soil medium changes from its natural value to a solid state, after which the soil simply moves to a certain distance from the axis of the cavity, compacting the neighboring massifs. Results. The hypothesis of the interaction of wedge-prismatic tips with the soil during static puncture is substantiated based on the determined law of soil density change along the thickness of the wedge-prismatic tip. Originality. The theoretical dependences for determining the rational parameters of the RO of wedge-prismatic form, the resistance of the sequential expansion of the TPG for the LPO after the starting passage of the leading hole, or the cavities of the primary expansion were obtained. Practical value. A method of determining the penetration force of the TPG for LPO after the leading pass is proposed, taking into account the elastic (reverse) deformations of the soil, its moisture, the shape of the RO, and the characteristics of the power equipment, as the difference between the full and pilot resistance of the soil puncture, as well as recommendations on the possibility of reduction o these forces by changing the shape of work equipment or soil moisture.&#x0D;

Normal human craniofacial growth and development from 0 to 4 years

Knowledge of human craniofacial growth (increase in size) and development (change in shape) is important in the clinical treatment of a range of conditions that affects it. This study uses an extensive collection of clinical CT scans to investigate craniofacial growth and development over the first 48 months of life, detail how the cranium changes in form (size and shape) in each sex and how these changes are associated with the growth and development of various soft tissues such as the brain, eyes and tongue and the expansion of the nasal cavity. This is achieved through multivariate analyses of cranial form based on 3D landmarks and semi-landmarks and by analyses of linear dimensions, and cranial volumes. The results highlight accelerations and decelerations in cranial form changes throughout early childhood. They show that from 0 to 12 months, the cranium undergoes greater changes in form than from 12 to 48 months. However, in terms of the development of overall cranial shape, there is no significant sexual dimorphism in the age range considered in this study. In consequence a single model of human craniofacial growth and development is presented for future studies to examine the physio-mechanical interactions of the craniofacial growth.