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Productivity of Wheat and Barley in Plots Associated with Young Pecan in Sidi Mbarek at North of Tunisia. The productivity of two agroforestry associations is studied in the region of Mateur north of Tunisia (bioclimate subhumid). This crop of durum wheat and barley in association with young people aged 8 pecan during unproductive phase (0 to 10 years) to promote the cultivation of this tree to dry fruit in the region, occupy the land and improve incomes of rural populations. The pecans are planted at a density of 5 m x 5 m while wheat and barley are sown on the fly (± 200 plants/m²) in the bands between the rows of pecan (EA), near the pecan (SA) and in field control without trees (TE) with similar soil and climatic characteristics. The results show that the yields of intercropping depend on the location of planting. The yields of durum wheat sown between rows of pecan (8.4 t / ha) and those of the control (8.6 t/ ha) are not statistically significant difference, while yields of corn planted near the pecan (3.5 t/ha) and those of the control (8.6 t/ha) have a very significant difference. The yield of barley sown between rows of pecan (6.2 t/ha), near the pecan (1.9 t/ha) and those of the control (8.6 t/ha) are significantly different. The competition of surface roots of pecan and shading of the branches are pointed in SA as the main cause of declining performance. The pecan coexists easily with winter annual crops because of phenological shift. This system is productive and sustainable when it is practiced beyond 1 m from the pecan.

Virtual reality (VR) platforms act as a potentially transformative tool in learning and teaching. The aim of this study was to examine pre-service teachers' (PST) perceptions about VR, inclusive of their beliefs about its capacity to be used as a teaching and learning tool. A case-study, conducted at an urban university in Australia involved a sample of n = 41. Participants' positive perceptions of VR in their teaching relate to its potential to engage learners, the immersive potential of the platform and the scope of VR to offer students experiences they might otherwise not have with other learning tools. Concerns expressed by PSTs include their relatively low self-efficacy to use VR in their teaching, monitoring-related matters, financial cost and implementing the technology in a safe and supportive way. There was a significant difference in PSTs' amount of self-efficacy to teach using VR when compared to their overall confidence to use digital technologies. PSTs typically had greater awareness of the immersive and engagement potential of VR and less awareness about its potential to foster and promote collaborative learning. This paper contributes to an emerging discourse regarding the possible applications of VR in educational environments and particularly in relation teacher-educator contexts.

Flat-slab system is widely used nowadays. Major and critical problem of this system is its sudden brittle failure is called punching shear failure. To overcome the punching failure problem, there are many ways to increase the punching shear strength of concrete slabs, increasing slab thickness in the area adjacent to the column, increasing column thickness which is against the architectural desire, and finally providing slab with shear reinforcement. Shear reinforcement is more advanced from both the structural and economical point of view.An experimental program includes seven full scale square flat slab interior column specimens tested under gravity loads. All slabs have same dimensions of 1700 mm × 1700 mm with thickness 160 mm and reinforcement ratio of 1.2%. Column was square of 200 mm length and 250 mm height. Elongated steel strips of 25 mm width and 1.5 mm thickness undulated into the slab in different ways to investigate punching shear resistance.The program is divided into five groups. First group investigates the effect of installing the shear-band reinforcement (hanged up on top mesh, knit the top and bottom mesh together). The second group investigates the effect of inclination of shear reinforcement (shear band with vertical leg, with bended leg 45°). The third group investigates the effect of concentrating the shear reinforcement by increasing the quantity around the column. The fourth group investigates effect of radial distribution of shear-band system around the column. Finally, the fifth group investigates the effect of box distribution of shear-band system around the column. Keywords: Flat slab, Shear band, Punching shear, Failure load

One of the major problems of flat slab is the punching shear failure of slab-column connection. This form of failure must be avoided.Fourteen slab-column connections are tested to failure and categorized in two phases. The first “Phase I” consisted of testing ten interior square slabs axially loaded. The second “Phase II” consisted of testing four specimens under eccentric loading to study the influence of moment transfer at the slab-column connection on the punching shear failure of the slabs. The main parameters evaluated were, fiber volume ratio which was 0.5%, 1.0% and 1.5% and, punching area as dimensions of the square portion of the slab having steel fibers at the column vicinity of lengths d + 200 mm, 2d + 200 mm and 3d + 200 mm. All slabs have same dimensions of 1700 mm × 1700 mm with thickness 150 mm and reinforcement ratio of 1.2%. All tested specimens were loaded incrementally up to failure. However using steel fiber increased both the failure load and energy absorbing capacity. Summarily, it was found that slabs with a 1.5% steel fiber ratio led to high failure load capacity. Results showed that using steel fiber only in a portion of slab that is equal to slab thickness from column face was sufficient to give the optimum enhancement in both failure load and ductility behavior. Three-dimensional finite element model was created to using ANSYS R14.5 ANSYS (2012) program to simulate the behavior of the tested specimens. Crack pattern, mode of failure and energy absorption were analyzed here in this study. Keywords: Flat slab, Steel fiber, Punching shear, Failure load

Transverse openings are often provided through reinforced concrete beams to accommodate utility ducts and pipes. Finite element analysis has been used in order to study this problem. Fifty-seven beams analyzed using finite element program ANSYS V12. The analysis results compared with fifteen experimental beams had been done by Ibrahim. Study beams have opening width and height of dimensions 200 × 100 mm and 300 × 100 mm. The centerline of the opening is at distance of 225, 300, 350 and 400 mm from the near support. Strengthening of all beams with opening came out to six types of different scheme around the opening using fiber-reinforced polymer (FRP). Scheme (1) is vertical and horizontal carbon fiber sheets around the opening, scheme (2) is inclined at 45° carbon fiber sheets around the opening in addition to horizontal one, schemes (3) and (4) are same of schemes (1) and (2) respectively but with glass fiber sheets, while schemes (5) and (6) are same as schemes (3) and (4) respectively but with an additional strengthening at flexural area at the middle of the beam with U shape. The reinforced concrete beams were modeled in ‘ANSYS V12’ Program under statical load. The failure loads, crack pattern, strain progress, mode of failure and energy absorption were analyzed here in this study.

Three-year-old seedlings of two Tunisian provenances of cork oak (Quercus suber L.) differing in climatic conditions at their geographical origin were subjected to increasing light intensities. Ga’four was the provenance from the driest site and Feija from the wettest site. Low-light adapted seedlings from both provenances were exposed to two light treatments: full sunlight (HL) and low light (LL, 15% sunlight) for 40 days. The CO2-response curve of leaf net photosynthesis (An-Ci curve) established under saturated photon flux density was used to compare photosynthetic parameters between leaves subjected to continuous low light (LL leaves) and leaves transferred from low to high light (HL leaves). Transfer from low to high light significantly increased net photosynthesis (An) and dark respiration (Rd) in Ga’four provenance but not in Feija. After transfer to high irradiance, specific leaf area (SLA) did not change in either provenance. This suggested that the increase in photosynthetic capacity on a leaf area basis in HL leaves of Ga’four provenance was not due to increased leaf thickness. Only the seedlings from the Ga’four provenance were able to acclimate to high light by increasing Vcmax and Jmax.