Side wind and tank speed influence on lateral displacement of the projectile

This article indicates the scope of the formula for determining the magnitude of the lateral displacement of the projectile under the action of crosswind, which is used in the compilation of firing tables. This formula is valid under the following conditions: the force of frontal air resistance to the motion of the projectile is proportional to the its velocity squared; wind speed components are much smaller than the horizontal component of projectile velocity; the projectile velocity projections on the Oy and Oz axes are much smaller than the projections on the Ox axis; the dimensionless coefficient of resistance and the magnitude of the crosswind are constant values. However, in reality, the force of frontal air resistance to the motion of the projectile is only sometimes proportional to the its velocity squared; the projectile velocity projections on the Oz axis may be are much smaller than the projections on the Ox axis and may even be greater than it; the coefficient of resistance is depends on the value of the Makh number, so it can be considered constant only when shooting at short distances. The authors propose a mathematical model for determining the magnitude of the lateral displacement of the projectile under the action of crosswinds. It is believed that the force of the crosswind on the projectile depends on the following factors: air density; the maximum area of the longitudinal section of the projectile; the difference between the value of the lateral component of the wind speed and the speed of the lateral displacement of the projectile, which is raised to a certain power. The magnitude of the values of the lateral displacement of the projectile under the action of the crosswind when shooting at short distances, determined based on the proposed mathematical model, slightly differ from the values of the lateral displacement specified in the firing tables. However, with increasing firing distance, the difference between these values is constantly increasing and the value of the lateral displacement of the projectile determined theoretically is much larger than indicated in the firing tables. In addition, in this research the influence of the tank velocity on the value of the projectile lateral displacement taking into account the action of the crosswind is studied.

Hydrologic Performance of Experimental Green Roofs Stands as the Effect of Climate Condition

The water storage capacity of a green roof forms several benefits for the building and its environment. The hydrologic performance is traditionally expressed by the runou coefficient, according to international guidelines and standards. The runoff coefficient is a dimensionless coefficient relating the amount of runoff to the amount of precipitation received. It is a larger value for areas with low infiltration and high runoff (pavement, steep gradient), and lower for permeable, well vegetated areas (forest, flat land). The paper is presenting 3 experimental stands of green roofs. Each stand is unique in terms of its construction. The aim of this paper is to highlight how green roof responds to real clima events. The experiment provides mathematical graphs and behaviour of the geen roof stands from 03/2019 to 01/2021.

Is N = 2 Large?

We study θ dependence of the vacuum energy for the 4d SU(2) pure Yang-Mills theory by lattice numerical simulations. The response of topological excitations to the smearing procedure is investigated in detail, in order to extract topological information from smeared gauge configurations. We determine the first two coefficients in the θ expansion of the vacuum energy, the topological susceptibility χ and the first dimensionless coefficient b2, in the continuum limit. We find consistency of the SU(2) results with the large N scaling. By analytic continuing the number of colors, N , to non-integer values, we infer the phase diagram of the vacuum structure of SU(N) gauge theory as a function of N and θ. Based on the numerical results, we provide quantitative evidence that 4d SU(2) Yang-Mills theory at θ = π is gapped with spontaneous breaking of the CP symmetry.

Regularities of changes in microhardness in the volume of EDT-69N binder cured at different temperatures

The change in the microhardness over the thickness of samples made of EDT-69N binder cured in vacuum and at atmospheric pressure at temperatures from 130 to 170°C was investigated. It was found that the change in microhardness along the thickness of the samples occurs according to the parabolic law, with the maximum values being achieved in the middle of the sample cross-section along the thickness. With an increase in the molding temperature, the microhardness in the middle section of the sample increases from 222 MPa at a molding temperature of 130°C to 410 MPa during molding at 170°C. At the critical molding temperature (170°C), the microhardness in all zones of the specimen cross section (subsurface, semi-average, and core) levels off, while the parabolic dependence degenerates into a straight line. It is shown that the method of scratching (sclerometry) demonstrated a sufficiently high sensitivity to the state of samples cured at different temperatures. With an increase in the molding temperature, the width of the sclerometric grooves decreases. At a critical molding temperature of 170°C, the groove width is stabilized and becomes constant throughout the sample thickness. To characterize the difference in the values of the microhardness of the cured binder in the sample volume, it is proposed to use a dimensionless “coefficient of volume anisotropy,” which can take a positive, negative or zero value. With an increase in the curing temperature of the binder and, accordingly, with an increase in the microhardness of the sample, the coefficient of volume anisotropy decreases, and when the samples are molded at the critical temperature, it turns to zero, which indicates the absence of anisotropy.

An Analytical Model for Capturing the Decline of Fracture Conductivity in the Tuscaloosa Marine Shale Trend from Production Data

Fracture conductivity decline is a concern in the Tuscaloosa Marine Shale (TMS) wells due to the high content of clay in the shale. An analytical well productivity model was developed in this study considering the pressure-dependent conductivity of hydraulic fractures. The log-log diagnostic approach was used to identify the boundary-dominated flow regime rather than the linear flow regime. Case studies of seven TMS wells indicated that the proposed model allows approximation of the field data with good accuracy. Production data analyses with the model revealed that the pressure-dependent fracture conductivity in the TMS in the Mississippi section declines following a logarithmic mode, with dimensionless coefficient χ varying between 0.116 and 0.130. The pressure-dependent decline of fracture conductivity in the transient flow period is more significant than that in the boundary-dominated flow period.

Динамическая модель упруго-пластического нормального столкновения сферических частиц при нелокальной пластичности

The problem of normal collision of a spherical particle with a half-space is considered with allowance for nonlocal plastic deformation in the case where the strength limit depends on the contact radius, as well as for the strengthening effect in the deformed material. The dimensionless coefficient of normal velocity restitution has been calculated numerically as a function of the initial velocity of the spherical particle. The obtained data coincide well with experimental results available in the literature.

Analysis of the stress-strain state of a tank in case of irregular subsidence along the periphery

In the article, the authors proposed a calculation model for determining the SSS of a vertical steel tank in case of irregular subsidence of the external bottom contour in accordance with the geometric parameters of a real RVS-20000 m3 tank. An experiment is planned and presented including a scheme with two influencing factors: the geometric model of the tank and the value of the dimensionless coefficient m. The influencing factors have 3 and 5 combinations respectively, which is represented in the experiment matrix. The article shows diagrams of displacements, stresses of the tank structures, and graphically depicts the dependences of the displacements of shells on the values of subsidence zones. The presence of a stiffening ring and a stationary roof provides the least values for vertical and horizontal displacements. Conclusions about the influence of the factors considered on the SSS of a tank in case of irregular subsidence of the external bottom contour are presented.

The Effects of Split Drag Flaps on Directional Motion of UiTM’s BWB UAV Baseline-II E-4: Investigation Based on CFD Approach

This paper presents a study about split drag flaps as control surfaces to generate yawing motion of a blended wing body aircraft. These flaps are attached on UiTM’s Blended Wing Body (BWB) Unmanned Aerial Vehicle (UAV) Baseline-II E-4. Deflection of split drag flaps on one side of the wing will produce asymmetric drag force and, as consequences, yawing moment will be produced. The yawing moment produced will rotate the nose of the BWB toward the wing with deflected split drag flaps. The study has been carried out using Computational Fluid Dynamics to obtain aerodynamics data with respect to various sideslip angles (ß). The simulation is running at 0.1 Mach number or about 35 m/s. Results in terms of dimensionless coefficient such as drag coefficient (CD), side force coefficient (CS) and yawing moment coefficient (Cn) are used to observe the effects of split drag Subscript text flaps on the yawing moment. All the results obtained shows linear trends for all curves with respect to sideslip angles (ß).

Influence of a Weak Superposed Centripetal Flow in a Rotor-Stator System for Several Pre-Swirl Ratio

The present study is devoted to the influence of a superposed centripetal flow q in a rotor-stator cavity with a peripheral opening. In the literature, previous works have already shown that a weak radial inflow has no major influence near the periphery of the cavity, whereas the flow behavior is strongly modified when approaching the axis [1–2]. The challenge of this work is to give a better understanding of this phenomenon. Attention is focused on a rotor-stator system characterized by a small gap ratio G and high Reynolds number Re, so that the flow is divided into two boundary layers separated by a core region, according to the classification by Daily and Nece [3]. Until now, numerous authors obtained analytical solutions for the central core flow behavior: following the analysis performed by Schlichting [4], and assuming that the evolution of the velocity in the Ekman boundary layer corresponds to a 1/7 power law, Poncet et al. [2] proposed an analytical law predicting the evolution of the core swirl ratio K versus a local dimensionless coefficient of flow rate Cqr. Debuchy et al. [5] improved this last solution by taking into account the radial exchange of fluid outside the boundary layers. This last approach was used by Abdel Nour et al. [6] in a rotor-stator cavity without any superposed flow (isolated cavity). They obtained an original analytical law, different from the classical similitary solution proposed by Batchelor [7] in the case of infinite disc, convenient for a cavity with peripheral opening and small pre-swirl ratio. In this paper, the authors present an original analytical law in order to model the central core flow behavior in a rotor-stator cavity subjected to a very weak inflow rate (q → 0). The validity of the solution is tested with the help of: • a new set of experimental data including the radial and tangential mean velocity measured by hot-wire anemometry, • experimental results from the literature.

Prehension Synergies in the Grasps With Complex Friction Patterns: Local Versus Synergic Effects and the Template Control

We studied adjustments of digit forces to changes in the friction. The subjects held a handle statically in a three-digit grasp. The friction under each digit was either high or low, resulting in eight three-element friction sets (such grasps were coined the grasps with complex friction pattern). The total load was also manipulated. It was found that digit forces were adjusted not only to the supported load and local friction, but also to friction at other digits (synergic effects). When friction under a digit was low, its tangential force decreased and the normal force increased (local effects). The synergic effects were directed to maintain the equilibrium of the handle. The relation between the individual digit forces and loads agreed with the triple-product model: fin = ki(2)ki(1)L, where fin is normal force of digit i, L is the load (newtons), ki(1) is a dimensionless coefficient representing sharing the total tangential force among the digits (∑ ki(1) = 1.0), and ki(2) is a coefficient representing the relation between the tangential and normal forces of digit i (the overall friction equivalent, OFE). At each friction set, the central controller selected the grasping template—a three-element array of ki(2)ki(1) products—and then scaled the template with the load magnitude.