Substantiation of the Parameters of Universal Scatterer for Bulk Materials

In the paper it is noted that the even distribution of seed and granules of mineral fertilizers inside the soil allows increasing their efficiency and obtaining a potential crop yield. For an even distribution of seeds of grain crops, herbs and fertilizer granules inside the soil, the use of a universal conical scatterer is proposed. The purpose of the study is to substantiate the parameters of a universal conical scatterer, which ensures an even distribution of metered bulk and hard-flowing materials, in particular, seed and granules of mineral fertilizers inside the soil. The results of studies of the conical scatterer of an opener allow to establish that to obtain an even distribution of materials in the direction transverse to the translational speed it is necessary to cut an elliptical section of the scatterer. The cutting plane should be perpendicularto the translational speed (movement direction) at an angle between it and the central axis of the cone, lower than Π 2. The optimal parameters of the conical scatterer are calculated on the basis of the evenness of the particle descending along the conegeneratrix. The revealed dependence of the particle falling time on the initial dimensions of the scatterer made it possible to establish its optimal parameters: the height of the cut-section 6-14 mm; the cone base diameter 100-140 mm. The universal conical scatterer can be used in any industry that requires even scattering of metered bulk and hard-flowing materials.

Результаты экспериментов по кристаллизации твердого раствора Ge-Si-Sb на космическом комплексе "Союз--Аполлон" в условиях микрогравитации

Objective factors that allow the experiment on growing crystals of a Ge–Si–Sb solid solution on the Soyuz–Apollo spacecraft to take a special place among many experiments on growing single crystals aboard spacecrafts are analyzed. In the study of crystals grown on board a spacecraft, anomalous and unexpectedly high segregation of the solid solution components in the direction transverse to the direction of crystallization is found. An analysis of the obtained results allowed us, for the first time, to establish a causal relationship between anomalous segregation and microgravity features on board a spacecraft. Determining the physical nature of anomalous segregation have affected the direction of further research and give rise to an in-depth study of specific features of the new technological environment, the rapid development of numerical methods for studying heat and mass transfer processes in melts, and the expanding of the range of studied crystals and methods for studying them. A great contribution to the development of this area was made by Professor V.S. Zemskov.

Effect of Scanning Routes on the Stress and Deformation of Overhang Structures Fabricated by SLM

Selective laser melting (SLM) is a promising manufacturing method for the construction of complicated precision parts. However, deformation of the overhang during the fabrication process and post treatment is still a common problem. In this paper, the effect of the scanning route on the residual stress and deformation of fabricated AlSi10Mg overhang specimens by SLM was investigated. Different scanning routes for the overhang including longitudinal direction, transverse direction, and the alternation between these two scanning routes in consecutive layers were studied by experiments within this study. Numerical simulation was utilized to measure the stress of the specimens while deformation prediction was used for the different scanning routes. Both the experimental and simulated results showed that the scanning route had a substantial influence on the residual stress and deformation of the specimens. The longitudinal scanning resulted in significant upward bending deformation of the overhang as it was cut from the baseplate. However, there was less deformation for the overhangs fabricated by transverse and alternating scanning routes. A transverse scanning route is helpful for the reduction of residual stress in the longitudinal direction and the corresponding deformation.

Effect of the Strain Kind on the Texture and Microstructure of Low-Alloyed Steel

Crystallographic texture and microstructure of low-alloyed steel after twist extrusion (TE) and subsequent cold rolling along and across the TE axis were studied. The double axial cylindrical texture with axes 110 and 100 parallel to the TE axis and the vortex-like microstructure are formed in the steel during the TE. The subsequent rolling of extruded steel along the TE axis promotes the forming of typical steel rolling texture as well as the microstructure with elongated grains in rolling direction. Typical steel rolling texture as well as the equiaxed microstructure is formed in extruded steel after rolling in the direction transverse to the TE axis. The mechanisms of formation of the texture are discussed.

Model Test Investigation of the Influence of Damping on the Vortex Induced Motions of Deep Draft Semi-Submersibles Using a Novel Active Damping Device

Vortex Induced Motions (VIM) of semi-submersibles occur when the vortex shedding frequency is close to the natural frequency of the semi-submersible in the direction transverse to the current. Recent studies suggest that the magnitude of VIM predicted during model tests is higher than that observed in the field. Among others, the damping effect provided by the risers and mooring lines is regarded as one of the reasons for this difference. In this paper the setup and results are presented for model tests to investigate the influence of damping on VIM. For these model tests an active damping system was developed, which introduces an actively controlled external force mimicking a damping force. This applied damping force is based on the floater sway motion and sway velocity. With this system the introduced damping level can easily be controlled and verified without changing the stiffness of the system. In this paper the advantages and disadvantages of this active damping system are presented. The VIM tests were conducted for two semi-submersibles: a paired-column semi with eight columns and a four column semi. Reduced velocities ranged from Ur=3 to Ur=10 and different levels of additional linear damping were applied to the floaters in the direction transverse to the current direction. Damping was found to reduce the VIM motions significantly: reductions of more than 60% were observed in the nominal A/D response for 25% equivalent linear damping. This indicates that damping has a significant effect on the global VIM response and thus should be considered in the design phase of the risers and mooring lines of the semi-submersibles. To improve the understanding of the driving mechanism of VIM and also to provide validation data for CFD analyses, forces were measured on each column of the four column semi. Column force measurements indicate that for the four column semi for 45 degrees heading, i.e. the heading with largest VIM responses, the upstream, the portside and the starboard side columns are exciting the VIM motions. For 22.5 degrees, the downstream, the portside and the starboard side columns excite the VIM motions. For all tested headings the pontoon always damps the VIM response.

The Brittleness Of Zn-Cu-Ti Sheet Alloys

At temperatures below 5°C, the ductility of ZnCuTi alloy sheets is observed to suffer a drastic drop in direction transverse to the rolling direction. Studies have shown that the critical temperature at which this phenomenon occurs is strongly dependent on the alloy structure and parameters of the sheet metal production process. Quite important is also the role of micro-inhomogeneity arising in the chemical composition of the alloy matrix, directly related with the structure of intermetallic precipitates containing Cu and Ti.

Research on Welding Deformation of Thick Plate Duralumin Alloy under A-TIG

Using A-TIG to welding thick plate duralumin alloy and designing rationally welding processing for Y groove butt plates welding of duralumin alloy. Using repeated measurements of dot to get transverse and vertical welding deformation under different current of A-TIG after welding. This paper analyzed the influence of different current on welding deformation and the features of A-TIG welding deformation. The result showed that transverse deformation was the uniformity along weld direction but was not uniform along weld vertical direction. Transverse deformation was larger when it was nearer to weld. Vertical deformation of middle position of weld was smaller than the part of arc starting and arc suppression. The result also showed that the deformation increased as the current increased.

Wind - terrain effects on the propagation of wildfires in rugged terrain: fire channelling

The interaction of wind, terrain and a fire burning in a landscape can produce a variety of unusual yet significant effects on fire propagation. One such example, in which a fire exhibits rapid spread in a direction transverse to the synoptic winds as well as in the usual downwind direction, is considered in this paper. This type of fire spread, which is referred to as ‘fire channelling’, is characterised by intense lateral and downwind spotting and production of extensive flaming zones. The dependence of fire channelling on wind and terrain is analysed using wind, terrain and multispectral fire data collected during the January 2003 Alpine fires over south-eastern Australia. As part of the analysis, a simple terrain-filter model is utilised to confirm a quantitative link between instances of fire channelling and parts of the terrain that are sufficiently steep and lee-facing. By appealing to the theory of wind–terrain interaction and the available evidence, several processes that could produce the atypical fire spread are considered and some discounted. Based on the processes that could not be discounted, and a previous analysis of wind regimes in rugged terrain, a likely explanation for the fire channelling phenomenon is hypothesised. Implications of fire channelling for bushfire risk management are also discussed.

Study on In-Flow Vibration of Cylinder Arrays Caused by Cross Flow

The authors have studied the in-flow vibration phenomena of cylinder arrays caused by cross-flow in the low Reynolds number range around Re=800. This Reynolds number range has been studied because it is the range where symmetric vortex shedding occurs. This report is our first trial to study the in-line fluidelastic vibration of cylinder arrays. In initial tests, the flow velocity was increased up to the maximum achievable level by the test equipment. However, it was found that the array’s cantilever tube supports resulted in large static tube deflections due to static drag forces. The cylinder array tube supports have therefore been replaced by thin plates supported at both ends. The cylinders are set to be flexible both in the streamwise direction and the direction transverse to the flow. The obtained results of these two patterns are also compared with previous cantilevered data. The origin of the observed vibrations whether a self-induced mechanism or vortex shedding is discussed in detail.