The Pumps as Turbines (PAT) is a well-established technology suitable for standalone micro-hydropower plants and energy recovery systems. But being lower performance than the dedicated turbines, there are continuous efforts to improve it keeping cost benefits intact. One of the recent modifications of the Back cavity filling plays a crucial role in the performance of PAT which is not investigated in detail. In the present paper, the PAT Back cavity is filled with a solid ring of various sizes and shapes (Back cavity filling) to explore its impact. The developed test facility is used to validate the experimental results with the numerical results for the base case. A numerical model after validation has been employed to investigate the impact of Back cavity filling on the internal flow dynamics and the PAT performance. Additionally, the study explored the influence of axial clearance on flow physics, associated losses, and the PAT performance, an aspect rarely discussed by researchers in the PAT mode. After Back cavity filling, secondary flow-based disk friction losses were reduced, leading to a 3.5 % increase in PAT efficiency. An analysis of the axial clearance showed that increasing it from 0.015 to 0.076 (mean axial gap/impeller radius) led to a 2.6 % reduction in PAT efficiency. This decline can be primarily attributed to elevated losses associated with disk friction, increased volumetric losses, and the formation of a mixing zone at the impeller inlet, which impeded the flow into the impeller's flow zone.

In this investigation a new procedure has been developed for producing of Cast Iron parts. The Cast Iron parts were produced as two layers during of solidification. They had two zones, outer zone which was Grey Iron and inner zone which was Ductile Iron. At first, a complex cast part with a blind riser was designed. Second, some inoculants were placed into the blind riser on a wire screen for inoculation of melt. Finally, the micro structure from the outer skin toward the inner zone of the part was investigated by metallographic testing. Results showed that graphite’s in outer layers were from type of flack graphite, and the central zones were spherical graphite. In fact, at the first step of solidification, outer skin is solidified as Grey Iron. Then due to contact melt and inoculants material concurrent with cavity shrinkage as well as Back pressure into the riser, a flow of inoculated melt move from the riser toward mold cavity. This phenomenon lead to formation of spherical graphite’s at the central zones. This procedure is very economic fore casting industries, because in this technique the blind riser has the role of a reaction cavity, instead of melt compensation.

Amygdaloidal, cavity- and fracture-filling zeolites in Eocene volcanic rocks from the Kuh-e-Aradeh of southern Kahrizak, in the northernmost part of Central Iran have been studied in some detail by optical, chemical analysis, SEM, and XRD techniques. The zeolites identified, in order of their relative time of formation from early to late, are tetranatrolite, analcime, natrolite, mesolite, stilbite-Ca, scolecite and heulandite-Ca. Formation of zeolites in the studied region began with a sodium zeolite of low Si/Al ratio and, with the gradual increase in calcium content and Si/Al ratio, ended with calcium zeolites. The zeolites were probably formed as a result of the late-stage hydrothermal activity in 60-150°C spans. Other associated secondary minerals in the region are calcite, opal, quartz, and pyrolusite. Chemical analysis of the host rocks showed that they are mostly andesitic, or, to a lesser extent basaltic, and the composition of one zeolite-bearing dyke is potassic trachybasalt.

Introduction: Several materials are recommended for retro filling. One of the best materials that have ever been suggested is MTA (Mineral Tioxide Aggregate). Many studies have confirmed the biocompatibility, proper marginal adaptation and salability of this agent. The purpose of this study was the evaluation of apical evaluation of apical microleakge in cavity preparation with different dimension for retrograde.Materials & Methods: In this study, we examined the influence of cavity dimension on salability of MTA. We selected sixty roots with a single canal. After cleaning and shaping, the canals were obturated with guta-percha and canal sealer by lateral condensation technique.Samples were divided into 5 groups: two positive and negative control groups and three experimental groups. cavity preparation was performed for all experimental groups with the following methods:A: 1.5mmdepth and 0.6mm widthB: 3mm depth and 0.6mm widthC: 3mm depth and 1.5mmwidthAfter cavity preparation, MTA powder was placed in each cavity and wet cotton adjacent to them for 24 hours. Then the samples were placed in Incubator (37°C and 100% wet) for 72 hours.Subsequently dye penetration examination was performed; dye leakage was measured by stereomicroscope. We used T-test for statistical analysis.Results: After statistical analysis these results were achieved:1. Increase depth from 1.5mm to 3mm reduce the amount of leakage.2. No significant difference between leakage of cavities with different width was found (P-value>0.05).Conclusion: It's better to prepare cavities for retrograde filling with more depth and less width.

Background: cavity preparation reduces the rigidity of tooth and its resistance to deformation. The purpose of this study was to evaluate the dimensional changes of the repaired teeth using two types of light cure composite and two methods of incremental and bulk filling by the use of finite element method. Materials and Methods: In this computerized in vitro experimental study, an intact maxillary premolar was scanned using cone beam computed tomography instrument (SCANORA, Switzerland), then each section of tooth image was transmitted to Ansys software using AUTOCAD. Then, eight sizes of cavity preparations and two methods of restoration (bulk and incremental) using two different types of composite resin materials (Heliomolar, Brilliant) were proposed on software and analysis was completed with Ansys software. Results: Dimensional change increased by widening and deepening of the cavities. It was also increased using Brilliant composite resin and incremental filling technique. Conclusion: Increase in depth and type of filling technique has the greatest role of dimensional change after curing, but the type of composite resin does not have a significant role.

Introduction: Implant-supported prostheses can be screw-type or can be cemented onto the abutment. Use of permanent cements, which are used in conventional prostheses, is not recommended for implant-supported prostheses. These cements are very strong and do not allow easy removal of the prosthesis. By using temporary cements not only permanent cement faults will be eliminated but also prosthesis can be retrieved as needed. The aim of this study was to evaluate the effect of screw access filling material and cement on the retention of implant cemented crowns. Materials & Methods: In this in vitro study, 5 angulated abutments (15° ) were screwed onto the analogue and ten crowns were fabricated for each of them. Four filling materials, Coltosol, composite resin, Teflon tape and silicone, were used to fill the access cavity and one abutment was left empty (only the screw was covered). Two temporary cements (Temp Bond and Temp Bond NE) were used to cement the crowns. The force required to remove the crowns was measured with a universal testing machine at a crosshead speed of 5 mm/min. Data were analyzed with ANOVA and Tukey test (α = 0. 05). Results: In all the samples, the force required to separate the casting crowns from the abutment were higher in Temp Bond NE group and this difference was statistically significant (p value = 0. 007). In addition, the difference between the access filling material was statistically significant (p value ˂ 0. 001). Therefore in each group, Coltosol, empty, composite resin, Teflon and the condensational silicone exhibited the highest means of separating force in ascending order. Conclusion: Retention of implant-supported crowns was influenced by types of filling material, access cavity and cement used.

A detailed analysis on the fluid flow distribution in the Back shroud cavity is significant for accurately calculating axial forces in the operation of centrifugal pumps. The numerical calculation results and the experimental results were basically consistent on the performance of the centrifugal pump and the fluid flow characteristics in the Back shroud cavity. Distribution of velocity field was researched in the Back shroud cavity. We plot the axial distribution curves of the dimensionless circumferential and radial components of velocity of the fluid inside the cavity with different angles and radii. We then analyze the fluid pressure distribution in the Back shroud cavity and compare it with experimental results. Results show that the fluid flow in the Back shroud cavity involves the core area and the fluid leakage. Results also show that the fluid in the core area behaves like a revolving rigid body. At the operating points of the same flow rate, the cross-sectional area of the volute directly affects the flow rate of the fluid in the Back shroud cavity, significantly restricting the fluid flow in that component. However, the flow pattern in the turbulent boundary layer is strongly affected by the leakage flow; hence, the distribution of velocity is not axially symmetric. When the flow rate increases from 0. 8 Qsp to 1. 2 Qsp, the radial differential pressure between the sealing ring and the volute decreases. Meanwhile, the disc friction loss of the impeller-to-wall inside the Back shroud cavity tends to be more circumferentially or radially equal, whereas the radial leakage rate in the Back shroud cavity tends to decrease. The fluid flow in the Back shroud cavity comprises the circumferential shear flow and radial differential pressure flow and is considered as a 2D viscous laminar flow.