Quadrangular Plate Research Articles

Calculation of parameters of anchor-sprayed concrete support vertical mining operations

The issues of assessing the stability and fastening of horizontal and vertical mine workings, considering various mining and geological conditions, are relevant. The study of scientific papers related to this problem has shown that a fairly large number of works are devoted to developing methods for calculating and applying anchor-sprayed concrete support for the walls of horizontal mine workings. At the same time, there is no design model for using such a support for the trunks of vertical mine workings. In the proposed work, the method proposed in the previous work of the authors [1] is used to calculate the parameters of the anchor support of the trunks of vertical workings. To develop a methodology for calculating the thickness of the sprayed concrete coating, a model of a quadrangular plate was adopted, and methods of the theory of elasticity were applied, similar to the problem of calculating boiler walls reinforced with anchor bolts, first solved by academician A.S.Leibenzon. As a result, a new formula for determining the thickness of sprayed concrete for vertical shafts is proposed, taking into account the steps of installing anchors horizontally and vertically and the influence of the lateral rebound coefficient under the action of a gravitational stress field. The problem of determining the strength limit of anchors on a slice interacting with a sprayed concrete coating is solved. An expression is obtained for determining the minimum value of the shear stress for the applied anchors at depth in rocks with a density; a formula is derived that allows determining the upper limit of permissible distances between anchor belts vertically, different from previously known similar formulas in that it takes into account the effects of the radius of the zone of destroyed rocks, the thickness of the sprayed concrete and the ultimate strength of the sprayed concrete. In addition, in its structure, there is a factor of the angle of inclination to the horizon of the most dangerous sliding plane. Based on the results obtained, it can be concluded that a technique has been developed that allows the calculation of a combined anchor-sprayed concrete support for small vertical shafts, optimize the values of the parameters of such support and create a corresponding mathematical model.

Distribution of temperature and stresses in a quadrangular plate

The presented paper shows the thermal analysis of a non-homogeneous isotropic quadrangular plate occupying the section D: b ≥ y ≥ 0; a ≥ x ≥ -a. The equation is generated with the known limiting conditions. The distribution of a temperature and unknown gradient of the temperature are used to evaluate the stresses in the plate. Displacement parameter is also used to identify the stress which is thermally checked along the edge of the plate. We have identify the unknown temperature gradient, displacement and thermal stress at the edge b = y. The stresses are evaluated by using Fasulo and Marchi’s technique. Laplace transform is also use for identifying the thermal stress in the plate. All results of the numerical are i.e displacements,stresses, distribution of temperature are illustrated graphically for a pure aluminum quadrangular plate with the properties of the material.

Development of the single-setup milling process model of the shaft support necks and cams

Three-dimensional geometrical modeling of the processes of allowance removal and shaping of support necks and cams of camshafts when milling with crossed axes of the tool and part is proposed. Single-setup milling of camshafts, which are widely used in automotive, tractor, shipbuilding and other industries, is carried out by a cutter with crossed axes of it and the part. The rotation angle of the cutter is selected from the condition of providing the required roughness of the treated surface and is regulated by the feed. At the same time, high processing productivity is provided by an increase in camshaft speed. A method of milling support necks and cams is developed, where the processing is carried out by a cutter, the height of which is less than the lengths of the processed surfaces. When processing the passage, the main allowance is removed by the end face of the quadrangular roughing carbide plate, and the finishing is carried out by the unloaded periphery of the cermet finishing plate. This allowance distribution increases the productivity and accuracy of processing, and the ability to rotate the roughing plate saves material and reduces the cost of processing. In the process of milling the curved surface of the camshaft cam, the depth of cut along the machined profile is always greater than the value of the removed allowance. This causes a decrease in the accuracy and productivity of processing. In order to eliminate this problem, it is proposed to stabilize the depth of cut and feed along the contour with uneven rotation of the part. The uniformity of the depth of cut and feed along the curved contour of the cam is achieved by simultaneous vertical and transverse movements of the cutter and uneven rotation of the camshaft. When milling the curved surface of the cam, the center of which does not coincide with the camshaft center, there is an uneven rotation of the latter and synchronous vertical and transverse movement of the cutter. When machining the cam section, the center of which coincides with the camshaft center, the cutter is given only rotation

Assessment of biomechanical properties of specially-designed miniplate patterns in a mandibular subcondylar fracture model with finite element analysis and a servohydraulic testing unit.

The aim of our study was to compare the biomechanical stability of three different systems used to fix mandibular condylar fractures on synthetic polyurethane mandibles using a servohydraulic testing unit and finite element analysis (FEA). We measured the resistance to displacement loads causing 1.75 and 3.5mm displacements of the fragments, and the maximum resistance values before failure of the fixation system in 30 condylar necks of 15 polyurethane mandible models. The three subgroups investigated were arranged as a triangular plate (n=10), a quadrangular plate (n=10), and a straight miniplate (n=10). The most successful fixation pattern was achieved with two straight four-hole miniplates. However, the triangular plate can easily be applied as a second option by an endoscopic approach. The rectangular plates showed no success in mandibular condylar fractures.

The influence of orientation of blast loading on quadrangular plates

This paper presents the results of experiments and numerical simulations carried out to characterise and assess the effects of orientation of blast loading onto a quadrangular plate. The study was carried out in two distinct arrangements. In one configuration, the explosive was tilted at different angles (0° (use as baseline for comparison), 15°, 30° and 45°) with respect to the target plate to provide different impact angles of the shock wave front with respect to the plate. In the other configuration, the target plate was tilted at two different angles (15° and 45°) with respect to the explosive. The blast load was achieved by detonating a 38 mm cylindrical disc of explosive. The stand-off distance, defined as the distance between the plate and the centre of the nearest face of the explosive cylinder, was kept constant at 40 mm. The mass of explosive was varied between 8 and 28 g of PE4 to achieve different responses of the plate ranging from large inelastic deformation to tearing of the structure. For all the different loading scenarios, the target plate consisted of a 2 mm thick DOMEX steel quadrangular plates with an exposed area of 300 × 300 mm. Each loading scenario was quantified in terms of impulse imparted onto the target in the axial direction of a horizontal ballistic pendulum. The damage was evaluated in terms of maximum deflection/tearing of the target plate. Numerical simulations was carried out in ANSYS® AUTODYN® using a coupled Eulerian and Lagrangian solver approach to provide insights in the mechanism of the blast load in terms of load distribution on the target plate.

Open reduction and Internal fixation of mandibular subcondylar fractures with quadrangular plate - A Case Report

Mandibular condylar fractures are the most commonly encountered mandibular fractures, being 17.5–52% of all mandibular fractures. The most common unilateral fracture is subcondylar, and the most common bilateral fracture is of the condylar heads, mostly caused by direct trauma, but may also be due to indirect forces. Treatment of condylar fractures depends on physical and imaging evidence of the fracture, extent of injury (whether unilateral or bilateral), the level of fracture, the degree of displacement and dislocation, the size and position of the fractured condylar segment, and the dental malocclusion.

Arthrodesis of the thumb carpometacarpal joint using a quadrangular plate: surgical technique and long-term results of 70 patients.

To assess the long-term results of trapeziometacarpal arthrodesis using a quadrangular plate, regarding clinical, radiological and functional outcomes, as well as development of complications. From 2005 to 2015, 70 patients were treated at our institution for primary osteoarthrosis of thumb carpometacarpal joint performing a trapeziometacarpal arthrodesis. A total of 85 arthrodesis were carried out using a titanium quadrangular plate (Proflyle plate, Stryker®, Kalamazoo MI, USA), without grafting in any case. Pre- and postoperative functional data were assessed at the outpatient clinics using DASH, MWS and VAS. All patients were asked for their ability to perform basic daily activities before and after surgery. All patients were also asked about satisfaction and their return to their jobs after surgery. Pre- and postoperative radiological data were also assessed. There were 59 females and 11 males with an average age of 55years (range 44-60). In 66 cases arthrodesis was carried out in the dominant hand, in 45 cases the right thumb was involved, and in 40 the left thumb was involved; in 15 cases arthrodesis was carried out bilaterally. Preoperative average DASH score was 64 (range 50-85), postoperative average score was 25 (range 5-61). Regarding MWS, 51 patients obtained excellent results, 15 patients obtained good results and 4 patients referred poor results. The preoperative average score of VAS was 6 (range 5-10), which decrease to an average of 2 (range 0-3) after surgery; all those differences were statistically significant. All patients reported a mild loss of motion; however, all of them reported improvement to carry out daily activities. There were four cases of nonunion because of failure of fixation and two cases with dysesthetic scar. There was no development of osteoarthritis in adjacent joints. The average follow-up was 60months. The use of quadrangular plates for arthrodesis of the trapeziometacarpal joint is a safety and reproducible technique with a low rate of complications. Arthrodesis decreases pain and improves function in patients with primary osteoarthritis of the thumb carpometacarpal joint; in spite of a mild loss of motion, patients are satisfied with this procedure.

Theoretical analysis on the effect of uniform and localized impulsive loading on the dynamic plastic behaviour of fully clamped thin quadrangular plates

This paper presents an approximate theoretical analysis of inelastic behaviour of fully clamped thin quadrangular plates subjected to two different distributions of impulsive loading. The presented analysis has been developed based on plastic work of plate and kinetic energy in which it assumes that the plate behaves rigid perfectly plastic. The rigid plastic analysis uses an interaction yield surface based on reasonable assumption that only membrane force considers for plastic flow and employs the Cowper-Symonds equation to cater for material strain rate effect. In this study, the applied load is estimated by assuming the initial velocity field of flat plate based on the boundary conditions of plate and geometry of explosive charge setup. Obtained models predict final deflection of the quadrangular plate loaded by uniformly and localized loading. The proposed solution permits consideration of characteristic influence of the load and material on the response of plate. It is observed that the present theoretical models are in good agreements with experimental results and also in comparison with other approximate solution, the present models are found to be simpler and in better agreements with experimental values.

Incrusting Stenolaemate bryozoans from the Callovian (Middle Jurassic) of the Bryansk region, Russia

Four species of encrusting bryozoans (Tubuliporina, Stenolaemata), namely, Oncousoecia alexandri sp. nov., Guzhoviella improvisa gen. et sp. nov., Microeciella dyatjkovensis sp. nov., and Stomatopora bajocensis (d’Orbigny, 1850), are described from the Middle Callovian of the Bryansk region. The last species has been only known from the Middle Jurassic of western Europe. The new genus has an unusual ramification pattern at early astogenetic stages. The ancestrular and postancestrular branches do not bifurcate. The short postancestrular oligoserial branch is shaped like a quadrangular plate from each corner of which oligoserial branches extend to pass into multiserial fanlike branches either immediately or after bifurcation.

Resultados del tratamiento quirúrgico de la rizartrosis mediante artrodesis trapeciometacarpiana con placa de osteosíntesis cuadrangular

Objective To review the results of thumb trapeziometacarpal arthrodesis fixed by a quadrangular plate in osteoarthritis of the trapeziometacarpal joint. Materials and methods A retrospective review of trapeziometacarpal arthrodesis was performed. Sixteen arthrodesis with quadrangular plate fixation were performed on 14 patients. The mean age was 54 years (range 44–60). The dominant hand was involved in 8 cases. The mean follow up was 28 months (range 10–46 months). The DASH score and Mayo Wrist Score were used for functional evaluation. The visual analogue pain scale was used for pain evaluation. The ability to perform activities requiring use of the thumb and ability to return to work were also analysed. X-rays were evaluated to determine the consolidation rates and development of adjacent joint degeneration. Results DASH score improves from 60 (range 50–85) to 25 (range 5–61) points. The overall mobility was decreased, but the results regarding the performance of daily living activities were improved. All but one patient return to their previous work. The average pain score improved from 6 (range 4–10) to 2 (range 0–9). There were no cases of radiographic degeneration progression in adjacent joints. Arthrodesis consolidation was achieved in all cases. Conclusion Trapeziometacarpal arthrodesis is a reliable procedure for thumb osteoarthritis.

Fornemt skrin – i en kvindegrav fra vikingetid

Fornemt skrin – i en kvindegrav fra vikingetid

Fan Septoplasty for Correction of the Internally and Externally Deviated Nose

With recent exception, the history of septal surgery has predominantly been characterizedbyaslowprogressiontowardconservatism.Theearliesttechniquesused transmucosalreductionsofdeviations.Aswithallnewsurgicalapproaches,longterm complication rates and failures began to emerge. The resulting problems of septal perforation and nasal collapse prompted the development of the submucous resection technique by Freer 1 and Killian, 2 which was less radical in nature, preserving a mucoperichondrial cover. 1,2 This allowed for manipulation of the cartilaginous and bony septal framework without violating the integrity of the septal mucosa. Although this was a significant advance for intranasal surgery, limitations existed and long-term results were unsatisfactory in selected cases. In severely deviated and externally deviated noses, the submucous resection was unable to address the most dorsal component of the quadrangular plate.

Scaling aspects of quadrangular plates subjected to localised blast loads—experiments and predictions

A series of experimental results on clamped mild steel quadrangular plates of different thicknesses (1.6, 2.0, 3.0 and 4.0mm) and varying length-to-width ratios (1.0–2.4) subjected to localised blast loads of varying sizes is reported. Disc shaped explosive charges of varying charge diameter-to-plate width ratios (0.2–0.37) and charge heights (1.8–14mm) are centrally positioned on quadrangular plates to provide impulses resulting in mid-point deflections in the range from two plate thicknesses to central plate tearing. The effects of varying both the loading conditions and the plate geometries on the deformation are described. A modified dimensionless number is presented for the quadrangular plate response when subjected to localised circular blast loading. In addition, numerical predictions are carried out and compared with experiments for a limited selection of plate geometries.

Genesis of nasal perforation in lepromatous leprosy; its prevention and care.

TEXTBOOKS of medical diagnosis commonly list syphilis, tuberculosis, and lupus erythematosus as the chronic diseases producing septal perforations. Each is purported to have a site of predilection for attack which is of diagnostic value; all are relatively rare. To this triumvirate should be added a commoner fourth, also having a site of predilection which gives it diagnostic value, lepromatous leprosy.1 By way of general review, the skeleton of the nasal septum in the human is composed of several component parts. Anteriorly are found the two medial crura of the alae, forming the columella. This is separated from the cartilaginous quadrangular plate of the septum by a short stretch of skin and subcutaneous tissue. The quadrangular plate sits on the palatine crest, which begins at the nasal spine and ends in the palatine division of the palate posteriorly. Superiorly, this plate acts as the support to the nonosseous portion of

XXI. Notice of a Stall-plate of Sir William Parr, K.G., Marquis of Northampton

At your suggestion, I have lately obtained for the British Museum an object of some interest, which has proved to be the Stall-plate of Sir William Parr, K.G., Marquis of Northampton, and brother to Queen Katherine Parr.It is a quadrangular plate of copper, gilt and enamelled, on which are engraved the arms of Parr with their quarterings.