Experimental study of the S-shaped load element of the soil tillage machine

This article discusses the design of the strut of a tillage machine in the form of an S-shaped power element, using flexible tubular elements (Bourdon springs). Racks of this type are proposed for copying the soil microrelief, maintaining the depth of soil cultivation using a hydraulic drive. The possibility of using the S-shaped rack of the tool of the tillage machine, using flexible tubular elements, to ensure the copying of the soil micro-relief, compliance with the specified working depth, has been experimentally proved. Evaluation of the sensitivity and traction capacity of the S-shaped load-bearing element of the rack will allow us to speak of the ability to create displacements within 120 mm and traction forces up to 1600 N, at a maximum pressure of 6 MPa. Keywords: SOIL TILLAGE, TOOL TILLAGE, FLEXIBLE TUBULAR ELEMENT, DEPTH OF SOIL TILLAGE

Multiple Tooth-Rowed Parareptile From the Early Permian of Oklahoma

The Dolese Limestone Quarry near Richards Spur, Oklahoma includes an elaborate system of caves which have been infilled with early Permian fossil rich sediments. In operation for more than a century, the quarry yielded vast numbers of disarticulated skeletal elements of the most diverse assemblage of fully terrestrial tetrapods from the Paleozoic. Excavations carried out in this century are distinct in producing large numbers of articulated and semiarticulated skeletons, including numerous new taxa. Dolese is therefore unique among early Permian localities in being home to a diverse assemblage of small parareptiles, including two species of Delorhynchus. Here we describe a new species of acleistorhinid, characterized by the presence of multiple tooth rows on the dentary, that can be identified with confidence as a third new species of Delorhynchus. The multiple tooth rowed condition is deemed not to be a pathological condition, and appears to have formed in the same manner as in the captorhinid eureptile Captorhinus aguti through uneven growth of the tooth-bearing element.

Strain localization and yielding dynamics in disordered collagen networks

Collagen is the most abundant extracellular-matrix protein in mammals and the main structural and load-bearing element of connective tissues. Collagen networks show remarkable strain-stiffening which tune the mechanical functions of...

ASSESSMENT OF STABILITY OF THE ROOF IN THE CARBON ART, WHICH CONTAINS PRODUCTS DURING THE DEVELOPMENT OF HARD COAL LAYERS

Purpose. Estimation of stability of a roof of a steep coal seam in the coal massif for maintenance of an operational condition of mine workings. Methods. To achieve this goal, analytical studies were performed using the basic principles of classical mechanics, the theory of elasticity and resistance of materials, when the roof of the coal seam was studied in the form of a model of a beam with a support. Results. As a result of the performed researches it is established that for an inclined single-girder beam with supports, at any regularity of distribution of loading on a surface the maximum deflection around the middle of span within (0,48 – 0,579) length of a beam is fixed. The value of the maximum deflection of the deformed load-bearing element depends on the angle of inclination and the ratio of the linear dimensions of the simulated beam. The curved axis is not perfectly symmetrical about the middle of the beam. The deviation from the symmetry depends on the linear dimensions of the model, the angle of inclination and is determined by the direction of the vector of total displacement of the beam. The deviation from the symmetry depends on the linear dimensions of the model, the angle of inclination and is determined by the direction of the vector of total displacement of the beam. The area in which the loss of stability of the load-bearing element is possible, occupies about 10% of the length of the inclined beam. In the presence of an asymmetrical deflection, to avoid loss of stability of the model, the placement of the system of supporting supports is advisable in this area of the beam. Scientific novelty. For the roof of a steep coal seam in its modeling in the form of an inclined single-girder beam with supports, when the external load is distributed on the surface naturally, the direction of the vector of complete displacement of the loaded model determines the contour of the curved axis of the deformed load-bearing element. Practical significance. The stability of the lateral rocks of the steep coal seam, which determines the operational condition of the mine workings in the coal massif, is provided by a system of supporting supports, the deformation characteristics of which are determined by the predicted deflection of the roof in the produced space. Keywords: stability, lateral rocks, coal massif, mining, deflection, supporting support.

Multi-objective optimization and significant analysis of bearing element adjustments on the static performance of an innovative adjustable bearing through design of experiment

Real-time position control of the journal in a hydrodynamic bearing demands continuous modification of the film thickness. Innovative adjustable bearings offer film thickness modifications in radial and circumferential directions through the flexible bearing elements. The position of the journal depends on the bearing element adjustments and the operating parameters. These adjustments also affect the static characteristic of the bearings. Hence, the position control requires an in-depth knowledge of the effects of bearing element adjustments on the bearing characteristics. In this paper, the main effect and the interaction effects of symmetric adjustment configuration of an innovative adjustable bearing at three levels are investigated through Taguchi method and ANOVA. Grey relational analysis is used to obtain the optimum bearing element adjustment. The results show that radial adjustment has the greatest influence on the attitude angle and tilt adjustment has a significant influence on the non-dimensional side leakage. The positive tilt, negative radial adjustment at 0.4 eccentricity ratio is the optimum bearing element adjustment for achieving a better static performance of innovative adjustable bearings.

Shining Light on the Light-Bearing Element: A Brief Review of Photomediated C–H Phosphorylation Reactions

Organophosphorus compounds have numerous useful applications, from versatile ligands and nucleophiles in the case of trivalent organophosphorus species to therapeutics, agrochemicals and material additives for pentavalent species. Although phosphorus chemistry is a fairly mature field, the construction of C–P(V) bonds relies heavily on either prefunctionalized substrates such as alkyl or aryl halides, or requires previously oxidized bonds such as C=N or C=O, leading to potential sustainability issues when looking at the overall synthetic route. In light of the recent advances in photochemistry, using photons as a reagent can provide better alternatives for phosphorylations by unlocking radical mechanisms and providing interesting redox pathways. This review will showcase the different photomediated phosphorylation procedures available for converting C–H bonds into C–P(V) bonds.1 Introduction1.1 Organophosphorus Compounds1.2 Phosphorylation: Construction of C–P(V) Bonds1.3 Photochemistry as an Alternative to Classical Phosphorylations2 Ionic Mechanisms Involving Nucleophilic Additions3 Mechanisms Involving Radical Intermediates3.1 Mechanisms Involving Reactive Carbon Radicals3.2 Mechanisms Involving Phosphorus Radicals3.2.1 Photoredox: Direct Creation of Phosphorus Radicals3.2.2 Photoredox: Indirect Creation of Phosphorus Radicals3.2.3 Dual Catalysis3.3 Photolytic Cleavage4 Conclusion and Outlook

DEVELOPMENT AND APPLICATION OF ISOLATION BEARING ELEMENT CONSIDERING BI-DIRECATIONAL COUPLED INTERACTION

Base isolation technology, which introduces isolated bearings between the top of foundation and upper structure, is regarded as an effective method to reduce seismic energy absorbed by the upper structure. Lead rubber bearing (LRB), that is, a representative seismic isolation device, has been widely used in isolated structural systems. An isolation bearing element for simulating the behavior of LRB was developed with the user element subroutine (UEL) feature of ABAQUS, which was further introduced into seismic analysis of the base-isolated structure with LRB. The Bouc-Wen bi-directional coupled restoring force model was adopted in the developed element to describe the nonlinear hysteric characteristics for LRB in the lateral direction. Meanwhile, the strength differences of LRB in the vertical direction were also included in the element. The accuracy of the isolation bearing element was verified by close agreement between numerically predicted hysteresis curves and experimental counterparts. Moreover, the nonlinear earthquake responses of a four-story reinforced concrete structure isolated by LRB with and without the bi-directional coupled interaction of bearing restoring forces were separately explored, and it was revealed that the bi-directional coupled interaction had considerable effects on the seismic responses of the isolated buildings. Once these coupled interaction effects were not taken into account, the displacement of LRB was underestimated while the bearing capacity would be over-predicted, which had a detrimental effect on the design of isolated buildings.

Taking into consideration the progressive collapse of civil buildings in foreign and domestic standards

The paper presents a review of foreign and domestic design standards for progressive collapse resistant buildings. The development of methods for structural analysis of buildings under a sudden bearing element removal is shown. The main differences between Russian standards and foreign guidelines in terms of progressive collapse analysis of buildings are highlighted.

Mechanized of Interlocking Brick and Its Structural Behaviour as Load Bearing and Non-Load Bearing Element-Review

Conventional bricks are the most elementary building materials for houses construction. However, the rapid growth in today's construction industry has obliged the civil engineers in searching for a new building technique that may result in even greater economy, more efficient and durable as an alternative for the conventional brick. Moreover, the high demands for having a speedy and less labour and cost building systems is one of the factor that cause the changes of the masonry conventional systems. These changes have led to improved constructability, performance, and cost as well. Several interlocking bricks has been developed and implemented in building constructions and a number of researches had studied the manufacturing of interlocking brick and its structural behaviour as load bearing and non-load bearing element. This technical paper aims to review the development of interlocking brick and its structural behaviour. In conclusion, the concept of interlocking system has been widely used as a replacement of the conventional system where it has been utilized either as load bearing or non-load bearing masonry system.