Tail Section Research Articles

Оптимизация формы шпангоутов и углов укладки полимерного композиционного материала силового набора хвостовой части легкого самолета

The paper presents the methodology for designing the load bearing elements of tail section of a light aircraft through the sequential application of methods of parametric and topological optimization. First, we analyzed the loads acting on the aircraft at its maneuvering in the vertical and horizontal planes. Then, for these loads, by the parametric optimization method, we selected the locations of ribs of the tail section of the aircraft, which were subsequently used to develop individual forms of ribs based on the topology optimization method. Next, we carried out parametric optimization of layup angles of polymer composite material, intended for the production of ribs. Finally, we developed a structural layout for the load bearing elements of the fuselage, which meets the criteria of minimum weight when restrictions are imposed on the level of stresses in some layers of the composite material.

Numerical study on long-duration performance of solid-fuel scramjet with size-fixed aft channel

In this study, the changing performance characteristics of a solid-fuel scramjet with a size-fixed aft channel for a long-duration operation were investigated using numerical methods. The results show that a solid-fuel scramjet with such a chamber configuration can continuously provide effective thrust over a long working period, followed by a long tail section of thrust. The effective working period lasts from the beginning of the operation to the moment when the bottom wall covered by the solid fuel is exposed to hot gas. The fluctuation in the thrust is significant due to the relatively large fluctuation in the equivalence ratio. The solid fuel utilization is relatively low; approximately 49% of the solid fuel remains after the effective working period. The configuration used in this study limits the mass flow rate passing through the front part of the cavity significantly, thereby forcing the core of the main recirculation zone to move downward rapidly, with undesirable effects on the equivalence ratio fluctuation and utilization of the front part of the solid fuel.

Sandy riverbed shoal under anthropogenic activities: The sandy reach of the Yangtze River, China

Large-scale reservoirs change downstream water and sediment conditions, causing adaptive adjustments in erosion and deposition along the riverbed, ultimately impacting sandbar morphology. This study examined the sandy reaches downstream of the China Three Gorges Project along the Yangtze River for river erosion and siltation, riverbed morphology, beach evolution, and other physical processes over the past 40 years, to explain the evolution of river geomorphology under human activities, such as reservoirs, improvement projects, and sand mining. The Shashi reach is approximately 52 km in length; it is the first sandy riverbed downstream of the China Three Gorges Dam. Analysis of topographic data from 1975 to 2018 showed that decreased sediment from the basin resulted in increased riverbed erosion (93.1%, in low-water channel), with sand mining activities destroying the integrity of the central bar. Simultaneously, total sandbar area decreased, thalwegs deepened, river morphological coefficients decreased, and the riverbed became narrower and deeper. The erosion and deposition patterns of the Shashi reach beach and channel have changed from “low shoal erosion-high shoal deposition” to “both low and high shoal erosion”. Additionally, waterway engineering has changed sandbar boundaries, and impacted the evolution of interactions among beach groups. Under quasi-natural conditions, strong interactions occur in sandbar evolution, such as the development of the Taipingkou Channel Bar (TPKCB), which led to Lalinzhou Point Bar (LLZPB) erosion, tail section widening, as well as Sanbatan (SBT) shrinkage and recession of its eastward edge. Owing to the implementation of waterway engineering, the linkage between the TPKCB and the upper section of the LLZPB weakened. The widening of the lower section of the latter has caused the SBT to shrink further and shift westward. Changes in the morphologies and dynamic axes of upstream beach groups have resulted in a sharp reduction of incoming sediment causing the downstream Jinchengzhou Point Bar (JCZPB) to gradually evolve into a shrunken channel bar.

Privileged scaffolds in medicinal chemistry: Studies on pyrazolo[1,5-a]pyrimidines on sulfonamide containing Carbonic Anhydrase inhibitors

We report for the first time a small series of compounds endowed in vitro with inhibitory properties for the human (h) expressed Carbonic Anhydrase (CAs, E.C. 4.2.1.1) enzymes of physiological interest (i.e. I, II, VA, IX and XII) and bearing the pyrazolo[1,5-a]pyrimidine (PP) scaffold at the tail section. Among the series reported, 1a-3a, 7a, 8a, 1b and 2b resulted effective ligands and with good selectivities for the hCAs II, IX or XII. In consideration of the nearly matching KI values of 7a for both the hCA II and IX (i.e. 26.4 and 23.0 nM respectively) we explored its binding mode within the CA IX mimic isoform by means of X-ray crystal experiments on the corresponding adduct.

Effects of compressible flow phenomena on aerodynamic characteristics in Hyperloop system

In this study, numerical simulations were conducted at various pod speeds (vpod= 100–350 m/s) using an unsteady, compressible solver with the Reynolds-averaged Navier–Stokes model to analyze the aerodynamic characteristics and pressure wave behavior in the Hyperloop system. Furthermore, the aerodynamic drag and pressure wave behavior were theoretically predicted based on quasi-one-dimensional assumptions. The flow around the pod is classified into three regimes according to the pod speed based on the compressible flow phenomena. In regime 1 (vpod= 100–170 m/s), the compression waves develop into normal shock waves even without the occurrence of choking at the throat. In regime 2 (vpod= 180–230 m/s), choking occurs at the throat and an oblique shock wave appears within the pod tail section. In regime 3 (vpod=240–350 m/s), a trailing shock wave propagates at the end of the oblique shock wave. Due to fully accelerated flow in this regime, the Mach number of the flow behind the pod in a pod-fixed coordinates remains constant as 2.1, regardless of the pod speed. This constant Mach number causes the drag coefficient to decrease while the pod speed increases. Although non-isentropic conditions such as the formation of a boundary layer and flow separation cause variation between the theoretical prediction and simulation results, the predicted properties of the pressure waves and the aerodynamic drag of the pod concur with the simulation results. Because the boundary layer along the pod is thinner at a higher pod speed, the difference between the theoretical and simulation values of the leading shock pressure decreases from 9.71% to 2.83% and that of the leading shock speed decreases from 4.39% to 1.30% as the pod speed increases from 180 to 350 m/s. Additionally, the theoretically predicted drag of the pod shows good agreement with the simulation results with an error of around 6%.

Formation of resistance of welded seams against forming of hot cracks when welding is performed with an increased speed

ABSTRACT The results of experimental studies of some features of non-consumable electrode welding in argon steel 12X18H10T with increased speed are presented. The possibility of improving the quality of formation and resistance of seams against the formation of hot cracks by exposing the arc and metal of the weld pool by controlling the magnetic field of the current flowing through the contact conductor located above the tail section of the weld pool, perpendicular to the electrode is shown.

On an Experimental Setup for the Determination of the Penetration Capability of the Tail Sections of Shaped-Charge Jets

On an Experimental Setup for the Determination of the Penetration Capability of the Tail Sections of Shaped-Charge Jets

Investigation of plastic properties of AISI 316l steel by method of registration of macrolocalization fields

Selective laser melting is one of the modern methods of manufacturing parts in the production of machine-building equipment, a special place is occupied by complex technological processes used in the manufacture of high-load units of pneumatic-hydraulic system from heat-resistant alloys. The research was carried out on samples made of powder material - stainless steel AISI 316L martensite class. Metallographic studies showed that the density of the sample is 99.83%, the structure of the samples is a martensitic structure of equilibrium constructed tracks. Tests to determine the mechanical properties were performed in accordance with ISO 6892 on an INSTRON test machine. From the tensile diagram it was found that the yield strength was 376.56 MPa, the maximum point of temporary resistance of the sample - 615, 40 MPa 319 seconds after the start of the test. The control of the surface roughness was performed using a BioBase device. The working area of the tensile sample consisted of two areas: a roughness area of 5 μm, which accounted for 80% of the working part of the sample (zones A and Б) and 20% of the working part of the sample (zone Б), the roughness was 17 μm. According to the results of microstructure studies and studies by the method of registration of macrolocalization fields of the working zone of the samples, it was found that the destruction began from the surface of the samples from microconcentrators due to different roughness. It is established that the surface and subsurface layer with increased roughness in comparison with the main body has a smaller elongation by 10.84%. From microstructural studies of the working zone in the area of the gap, it was found that the destruction began from the surface of the samples between zones A and Б. During the research in zone A and Б, one of the concentrators of the gap was detected. As a result of the study, it was found that the destruction began with the surface of the samples and the place of change of its roughness. The mechanism of deformation of the sample from AISI 316L steel is shown, the scheme of extraction of tail sections of tracks and crack propagation in the conditions of tensile testing of the sample is constructed.

Effects of fan volute structure on airflow characteristics in rice combine harvesters

Aim of study: Selecting a proper fan for the rice combine harvesters to get a good cleaning performance when harvesting high yield rice. Area of study: Jiangsu Province, China.Material and methods: Three potential multi-duct fans were designed, and the computational fluid dynamics and hot wire anemometer technology were utilized to learn the airflow and pressure variation inside the fan with perforated plates at the outlet ducts as cleaning loads. Then, the fan with the best performance was selected and a multi-duct cleaning test-bed was developed. The variation of the corresponding airflow velocity in the cleaning system was analyzed and the ideal airflow velocity in different section of the sieve was clarified. Finally, a field experiment was carried out.Main results: For a rice combine harvester with a feed rate of 7 kg/s (material other than grain + grain), the requested airflow rates inside the cleaning shoe was about 3.0 m3/s. The ideal airflow velocity in different section of the cleaning shoe was 8-9 m/s at upper duct, 4-6 m/s at the middle section, and 3-4 m/s at the tail section; large improvement in cleaning performance was achieved with the designed fan.Research highlights: The airflow velocity decreased as the cleaning loads at the duct increased. The fan with the averaged airflow velocity ≥7 m/s at the upper duct under different cleaning loads, and the airflow velocity at the lowest duct ≥ 9 m/s, is favorable for forming a blowing airflow in the tail sieve and is good for grain stratification.

Numerical simulation of the aerodynamics of a ballistic projectile for experimental development of standard samples

This article is aimed at developing a mathematical model and conducting numerical modelling of aerodynamic processes during the flight of a ballistic projectile using the method of computational aerodynamics. The use of a ballistic projectile as a prototype allows various units and systems of any size and mass to be included in the design of a guided artillery projectile. At the same time, the design of the developed ballistic projectile is characterized by simplicity, compact size and reduced weight. Several layouts of the proposed ballistic projectile with different tail sections were developed. The flow calculations were performed under the Mach numbers of M ∞ = 0.6, 0.8, 0.9 and the attack angles of α = 2° and a = 5°. Engineering calculations produced three-dimensional models of a ballistic projectile, flow patterns and main aerodynamic characteristics for various design layouts.

Measurement and evaluation of specific absorption rate and temperature elevation caused by an artificial hip joint during MRI scanning

A primary safety concern in a magnetic resonance imaging environment is heating of metallic implants by absorbing radiofrequency (RF) energy during MRI scanning. Experimental measurement in conjunction with computational modeling was used to evaluate the risk of biological tissue injury from the RF heating of artificial hip joints by obtaining both specific absorption rate (SAR) and temperature elevation at 1.5 T and 3 T MRI systems. Simulation result showed that high SAR and high temperature appeared near both head and tail sections of the artificial hip joints. For five different 1.5 T and 3 T MRI systems, measured temperature location showed that high temperature rises occurred near both head and tail regions of the metallic hip joints. Measured SAR value of 24.6 W/kg and the high temperature rise (= 4.22 °C) occurred in the tail region of the hip joint at 1.5 T, which was higher than the limits for temperature required by the international electrotechnical commission 60601-2-33. We have demonstrated the feasibility of evaluating RF heating of metallic hip joints during MRI scans.

THE PORTRAYAL OF HEGEMONY AS SEEN IN SNOWPIERCER

Snowpiercer is a sci-fi thriller movie directed by Bong Joon-ho. This movie presents the world’s survivors that live in a train creating their own economy and class system. The depiction of the movie is how power and ruling position could be achieved by conducting a process of moral and intellectual leadership rather than exercising full coercion. In Snowpiercer, Wilford as the dominant class attempts to gain power and authority to control the society through ideological indoctrination by the apparatuses. The study employs a sociological approach to literature to reveal the operation of hegemony in Snowpiercer. This study uses Antonio Gramsci’s concept of Hegemony as the main theory and Max Weber’s theory about power as supporting theory. In analyzing the data, this study uses a narrative and non-narrative approach. This study aims to describe hegemony through five stages of hegemony operation in Snowpiercer. Secondly, revealing the impact of hegemony on the subaltern class in Snowpiercer. Moreover, as the result shows that In Snowpiercer, hegemony is a process of gaining power through Indoctrinating ideology in which the role of coercive elements is necessary to maintain the power and authority obtained by the dominant class when the hegemony has weakened. This explains how hegemony conducted by Wilford lasts long and strong as it affects particular main aspects such as economic, military, education, culture, etc. Moreover, The dominant class's hegemony arises an impact on the subaltern class in the tail section, many people in the tail section get isolated, oppressed, and exploited.

Comparative Analysis of the Selection of Lay-Up Stacking of Polymer Composite Load-Bearing Elements for the Tail Section of Fuselage Structure of the Light Aircraft

The problem of the selecting the optimal lay-up stacking of polymer composite materials for the load-bearing elements of the rear part of fuselage structure is considered. The comparison of two approaches to the design of the load-bearing elements is carried out. The first of them is the use of multilayered composite material for the load-bearing elements, the stacking angles of which is selected from a given discrete set, and the second is the use of composite material with a continuous range of variables in fabric lay-up angles. As a result design optimization, it is shown that using an optimization method with a continuous range of lay-angles allows reducing the weight of the load-bearing elements by 12.79%

О постановке экспериментов по определению пробивной способности хвостовых участков кумулятивных струй

According to the calculations, the penetration effect of shaped charges can be significantly increased (by 40–50 % in the case of a high-strength steel target) if due increasing the accuracy of their manufacture the lower speed threshold is reduced at which the penetration of the tail sections of the shaped-charge jet into the target is stopped. For experimental confirmation of these data, it is proposed to study in detail the penetrability of the tail sections of shaped-charge jets using cut-off rods made of high-density material located at a short distance from the shaped charge (less than its diameter) and designed to eliminate the faster part of the jet. Based on numerical simulation in the framework of a two-dimensional axisymmetric problem of continuum mechanics, possible parameters of the cut-off rods for generating solitary "tails" of shaped-charge jets with different velocities of the leading element are predicted.

DEVELOPMENT OF STAGE-DISCHARGE RATING CURVE AND RATING TABLE OF PIYARO MINOR AND DILWARO MINOR

Developing a gauge-discharge relationship in rivers, canals, and minor flow is vital for controlling floods, managing water resources, Spatio-temporal analysis, socio-economic development, and sustaining the ecosystem. Accurate and consistent data of irrigation networks are perilous to scheduling and managing for accurate application of irrigation water. Most of the hydrologic engineering activities like hydraulics structure, designs, flood monitoring, surplus water, reservoir, canal, and minor’s operation depend on flowing water derived from Rating Curve (RC). The effective management of irrigation water is necessary for crop water requirements and seepage losses estimation. In this context, the present study showed the actual field level work tested at two minors of the Ghotki feeder canal namely Pyaro minor and Dilwaro minor. The main object of the study is to develop gauge-discharge relation and development of RC and Rating Table (RT). The current meter was used for taking discharge measurements with the area velocity technique in both minors. Moreover, stage-discharge RC and RT were developed for different flows of water for both minors in Origin Software. From the calculated results, Power equations were developed for both minors for the actual requirement of crop water in the command area. The results of the study calculated in RT of Piyaro minor between 0.5-5ft stage gave discharge 0.053 cusecs to 90.616 cusecs. While the RT of Dilwaro minor showed the range between 0.5ft-4ft stage gave 26.575cusec to 168.888 cusecs. Hence, the present study suggested that for both minors, automatic gauging stations should be established for the actual demand of irrigation water in the command area and di-siltation should be done on both minors to make availability of water at the tail section.

Handling drug-target selectivity: A study on ureido containing Carbonic Anhydrase inhibitors.

Here we report the synthesis of a series of taurine substituted sulfonamide derivatives 1-29 having the ureido moiety installed at the tail section as selective inhibitors of the tumor associated human (h) Carbonic Anhydrase (CA; EC 4.2.1.1) IX and XII. The series was deeply investigated for their kinetic features which demonstrated a strong dependence on the ureido moiety. High resolution X-ray crystallographic investigation on selected ligand adducts complexed with hCA II and hCA IX-mimic revealed a strong correlation between the ureido moiety and the amino acid residues Q92 and Q67 in both the hCA II and hCA IX-mimic, contributing to highly stabilized ligand-protein complex.

Methods to Reduce Material Intensity of Tail Sections of Launch Vehicles

A technique has been developed for reducing the material intensity of highly stressed tail sections of launch vehicles, taking into account strength and stability constraints as well as technological requirements. A cylindrical longitudinally and transversely ribbed waffle-grid (lattice) shell with rectangular holes is taken as the design scheme of the tail section, with its lower end being fastened at locations of support brackets, and the upper one being loaded with longitudinal compressive forces, evenly distributed along the contour, due to the action of the weight of higher-located structure elements. The optimization algorithm is based on the principle of ensuring discrete uniform strength of individual elements (substructures). The structural geometric dimensions of cross-sections of a standard tail section and the stiffness parameters of longitudinal and transverse load-bearing frames, the wall thicknesses of shell elements, the dimensions of lattice shells, etc., are selected from the requirements of stress-strength reliability: constraints on the limiting values of equivalent stresses (strength conditions), compressive stresses of the local and general buckling, and a number of design and technological requirements. The direct calculation of the tail section and the search for its variable geometric parameters are proposed to be performed using an interactive numerical-analytical (finite element method – engineering analysis) algorithm. The initial calculation of the static stress-strain state of the lattice-reinforced tail section was carried out by the finite element method, which is implemented in the NASTRAN package. To discretize the shell and its ribbing, flat finite elements were used. In the process of the finite-element numerical modeling of the tail section state, the reliability of the obtained results of calculating the equivalent stresses was analyzed by studying the convergence of the results of calculations on a series of meshes with different refinement. Results of the application of the developed technique to reduce the mass of the standard tail section of the Antares launch vehicle are presented.

Evaluating irrigation scheduling and application efficiency: baseline to revitalize Meki-Ziway irrigation scheme, Ethiopia

Irrigation scheduling and application efficiency were evaluated for Meki-Ziway irrigation scheme in an overall effort to revitalize the scheme. The evaluation was done on three furrows in each of the four farm plots. Field capacity, permanent wilting point and bulk density of the four plots were determined in the laboratory. We monitored furrow inflow rate, cutoff time and soil moisture content in the plots over a period of about 4 weeks. This monitoring was done during both periods of water availability and water scarcity. Our results show that on average 58% (range 42–77%) of the applied irrigation water in this scheme can be considered beneficial for crop growth. The results also show that soil moisture content at farm plots at the canal head sections was always between soil saturation level and permanent wilting point. For farm plots along the middle and tail sections of the main canal, soil water content would even fall below the permanent wilting point. This was caused by the absence of a water allocation system to ensure equity, and by large, channel seepage losses along the unlined main canal. To improve irrigation efficiency therefore, rehabilitation of the physical infrastructure of the scheme, more equitable irrigation water distribution in the scheme and improvement in on-farm irrigation water management are needed.

Fast adaptive fuzzy enhancement and correlation features analysis of flame image of sintering section

The state of the sintering end point can be indirectly reflected by the flame image characteristics of the material layer section at the end of the sintering machine. However, the image of tail section collected by industrial camera is easy to be interfered by smoke, dust and thermal radiation. As a result, the edge between the flame area and the material layer area becomes fuzzy, accompanied with halo and noise, which leads to the degradation of flame image. In order to solve the problem of image quality degradation, a new method based on weighted guided image filtering and fast adaptive fuzzy enhancement of flame image of sintering cross section is proposed in this paper; furthermore, the correlation analysis of the flame image characteristics of sintering section is carried out. The main contents of this paper include three parts: cross-sectional flame image enhancement, image brightness characteristics and geometric feature extraction, and image feature correlation analysis. The results show that the proposed method effectively eliminates the interference of noise and halo in the cross-sectional flame image. The brightness characteristics of the flame image are related to the length and height of the flame and the area of the red fire region, while there is no correlation between the brightness characteristics of the flame image and the centroid variance. Therefore, the brightness characteristics and the centroid variance can be used as the input feature for the discrimination of sintering state.

Selecting the mutual arrangement of the engine and wing in a transport aircraft for short take-off and landing

In order to maintain the competitive advantage of the medium short take-off and landing transport aircraft, the task must be solved of ensuring take-off and landing on the ground runways with a length of 600‒800 m when installing a turbojet engine. When the engines are installed on the pylons under the wing, this is achieved by using a «forced» turn of the jet of engines when the flaps are released at an angle of 60°. We have found the mutual location of the wing and the engine on its stagger, based on the position relative to the construction plane of the wing and the angle of installation. A reciprocal arrangement has been determined, making it possible to maximize the lift force owing to the turn of the jet stream. It has been shown that this achieves the continuous flow around the sections of the flaps when they are deflected at a 60-degree angle. We have analyzed the temperature effect of the jet stream on the mechanization and the aircraft wing at the stages of take-off and landing at different positions of engines under the wing, at different flight speeds and angles of attack. The effect of mechanization on the distribution of jet stream speeds and temperatures has been analyzed. It is shown that decreasing the distance between the engine nozzle and the lower surface of the wing leads to an increase in the angle of the jet stream deviation. We have identified those tail section zones of the flap, which require special execution to operate at temperatures above 400 °C. The impact of the jet stream on aircraft’s drag in the cruising configuration has been analyzed, as well as the scheme of engine arrangement on the aircraft’s electrically dependent systems. We have shown the absence of the impact of the jet stream on the aircraft’s drag in the cruising configuration, the reduction of fuel consumption at cruising modes, as well as the favorable impact exerted on the electrically dependent systems due to the significant reduction of gas-dynamic losses along the power plant tract. Ways to modernize the transport aircraft type of An-70 have been proposed to ensure its superiority in its class