In performance based design, the hazard levels and relevant acceptable damages are clearly specified. Structural and non-structural performances are controlled by limiting stiffness, strength and members ductility characteristics. Using displacement amplification factors (Cd) and force reduction factors (R) related to hazard levels, this paper present a method for determination of the stiffness and strength demands needed for BFS (Braced Frames) design. It means that two force reduction factors and two displacement amplification factors are introduced for moderate and major earthquake levels (Immediate Occupancy and Life Safety performances) for determination of stiffness and strength demands. These factors depend on ductility factor, force reduction factor due to ductility and overstrength factor. The procedure for determination of R and Cd factors and value of these factors for Io and LS performance level will be presented in this paper. The results indicate that force reduction factors and displacement amplification factors may be easily used in performance based design methodology.

This paper presents a numerical investigation for laminar forced convection flow of a radiating gas in a rectangular duct with a solid element that makes a backward facing step. The fluid is treated as a gray, absorbing, emitting and scattering medium. The governing differential equations consisting the continuity, momentum and energy are solved numerically by the computational fluid dynamics techniques. Since the present problem is a conjugate one and both gas and solid elements are considered in the computational domain, simultaneously, the numerical solution of Laplace equation is obtained in the solid element for temperature calculation in this area. Discretized forms of these equations are obtained using the finite volume method and solved by the SIMPLE algorithm. The radiative transfer equation (RTE) is also solved numerically by the discrete ordinate method (DOM) for computation of the radiative term in the gas energy equation. The streamline and isotherm plots in the gas flow and the distributions of convective, radiative and total Nusselt numbers along the solid-gas interface are presented. Besides, the effects of radiation conduction parameter and also solid to gas conduction ratio as two important parameters on thermo hydrodynamic characteristics of such thermal system are explored. It is revealed that the radiative Nusselt number on the interface surface is much affected by RC parameter but the radiation conduction parameter has not considerable effect on the convective Nusselt number. Comparison between the present numerical results with those obtained by other investigators for the case of non-conjugate problems shows good consistency.

Basalt fibre (BF)/acrylonitrile–, butadiene rubber (NBR) composites with various BF contents and orientations were prepared, and the curing, physical and mechanical properties and wear performance under block-on-ring abrasion conditions were evaluated. The results showed that the curing time was not obviously affected by the BFS. The addition of BFS increased the hardness but had negative influence on the tensile/tear strength of the NBR composites, especially when the BFS were oriented perpendicular to the tensile/tear direction with a high content, which should be due to the weak connection between the BFS and the rubber matrix. The coefficient of friction (COF) of the composites decreased significantly when BFS were added, whereas the content (3–, 30 phr) and the orientation of the fibres did not mainly affect the COF. Both parallel-and perpendicular-oriented BFS were effective at improving the wear resistance of the composites, and the former showed a better effect. With the BF content increase, the wear rate initially decreased and then remained basically stable. The COF and wear rate of the composites decreased by 27% and 35% when 12 phr BFS were added in a parallel direction. The excessive BFS, especially the perpendicularly-oriented BFS, led to fracture of the worn surface due to the abrasive grain wear caused by the crushed fibres.

Introduction: PMMA has been the most popular denture base material because of its advantages including good aesthetics, accurate fit, stability in the oral environment, easy laboratory and clinical manipulation and inexpensive equipments since the 1930’s. However, its fracture resistance is not satisfactory. Aim: The aim of this study is to improve the fracture resistance of denture bases made of PMMA by assessing the effect of resin type, packing and processing variables on biaxial flexural strength (BFS).Materials & methods: 930 discs, 12 mm diameter and 2 mm thick were prepared with the following variables: a. Veined (V) and Plain (P) PMMA. b. 5 different powder/liquid ratios by volume (1.5:1, 2:1, 2.5:1, 3:1, 3.5:1). c. Conventional (C) and Injection packing methods (I). d. Dry heat (D) Water bath (W); and e. different curing times. The discs were trimmed and stored in 37°C tap water for 50 hours before carrying out BFS test, according to BS EN ISO 1567: 2001. BFS test was carried out using a tensile-testing machine (Lloyd LRX, Lloyd instruments Ltd) (Figure.1 b), with a x-head speed of 1mm/min. ONE-WAY ANOVA analysis and TUKEY’S comparison were carried out (MINITAB). The temperature within the curing baths and inside of curing resin was evaluated by using a thermocouple. Results: BFS of Powder/liquid ratio of 1.5:1 is significantly lower than the other four ratios. Among the last four ratios, 2.5:1 was the strongest one although the difference was not significant. BFS of the plain type of PMMA is significantly higher than the veined type· BFS of conventionally packed PMMA discs was greater than the injectional packed ones and the difference is significant. Water bath cured resin showed a significant higher BFS compared with dry heat curing. · Changing the curing time in the dry heat bath from 7h @ 75º C and 2hrs @ 95º C to 5hrs @ 75º C and 3hrs @ 95º C and then 2hrs @ 95º C improves BFS of PMMA. In the water bath the trend is identical although the difference is not significant. Analysis of the temperature climb and hold within the curing bathes showed a consistent performance with the water bath irrespective the number of the flasks being cured. Meanwhile, the dry heat bath showed very inconsistent results.Conclusion: 1. Type of resin, packing procedure and processing variables can have major effect on BFS of PMMA. 2. Using plain resin, conventional packing, water bath curing with two hours at 95 ºC are recommended conditions.  

Background and Objective: Various techniques have been introduced to improve bond strength of zirconia which may negatively affect flexural strength. This study aims to evaluate the effects of different sandblasting parameters on micro-shear bond strength (MSBS, Mpa) and biaxial flexural strength (BFS, Mpa) of Zirconia. Methods: In this in vitro study, zirconia blocks were cut into 180 discs for MSBS and BFS tests (90 specimens in each group). For each test, they were divided into one control group and 8 experimental groups according to the type of sandblasting regimen (pressures of 4 or 6 bar, duration of 14 or 21 seconds, and alumina powder sizes of 50 or 110 μ, m, n=10). A universal testing machine was used to determine MSBS and BFS. X-ray diffraction (XRD) analysis was then performed. Findings: According to the results, groups with 110 μ, m particles (4 bar-14 s, 6 bar-14 s, 4 bar-21 s and 6 bar-21 s with MSBS values of 34. 43±, 5. 99, 35. 21±, 6. 39, 27. 17±, 3. 95 and 28. 66±, 3. 92 Mpa, respectively) had significantly higher MSBS values compared to the control group (p<0. 001, p<0. 001, p=0. 034, p=0. 005, respectively). Groups with 110 μ, m-21 s sandblasting regimen (with pressure of 4 and 6 bar with BFS values of 1031. 69±, 90. 00, 1062. 56±, 91. 29, 962. 30±, 93. 24, respectively) and those with 50 μ, m-6 bar-21 s sandblasting regimen had statistically significant lower BFS values compared to the control group (p<0. 001). According to XRD analysis, groups with 110 μ, m powder size and 21 s sandblasting resulted in more monoclinic phase. Conclusion: This study demonstrated that sandblasting with larger powder size and shorter duration could increase MSBS without any negative effects on BFS.

Introduction: Prostate cancer is now the third most frequent noncutaneous malignancy in Iranian men and the fifth most common cancer worldwide. Measurement of total serum prostate specific antigens (PSAs) has been one of the strongest predictors of biochemical progression and overall survival in determining the efficacy of definitive external beam radiation therapy in patients with localized prostate cancer. The aim of this research was to identify the 5-year biochemical progression-free survival (BFS) and related prognostic and predictive factors of localized prostate cancer patients who were treated with definitive external beam radiotherapy.Methods: This study analyzed 192 localized prostate cancer patients from stage T1aN0M0 to stage T3N0M0; they were treated with definitive radiation therapy and followed up in the radiation-oncology ward of Shohada-e- Tajrish Hospital in Tehran (Iran) between 2006 and 2013. The 5-year BFS was analyzed using the Kaplan-Meier estimate. For multivariate analysis, the Cox proportional hazards model was used to assess the strengths of various factors for 5-year BFS.Results: The follow-up period was between 14-81 months, with a median of 31 months. The median cumulative prostate dose in our series was 64 Gray (Gy) (range 62 to 78 Gy). The 5-year BFS for all patients was 65.1%, and 5-year BFS in low-risk, intermediate-risk and high-risk groups were 100%, 86.5%, and 54.9% respectively. Multivariate analysis found statistically significant relation between 5-year BFS and initial PSA>20, Gleason score 8-10, high risk group, TNM stage≥T2cN0M0, radiotherapy dose<70 Gy, radiotherapy with 2D technique and hormonal therapy in high-risk group (p=0.003, p=0.032, p=0.014, p=0.001, p=0.035, p=0.035, p=0.022 respectively).Conclusion: Our seven years’ experience of follow-up with PSA showed that PSA was the strongest predictor of biochemical progression survival in patients with prostate cancer who were treated with definitive external beam radiation therapy.

Background and Aim: This study evaluated the effect of hydrothermal aging on optical and mechanical properties of opaque and translucent zirconia. Materials and Methods: For the biaxial flexural strength (BFS) test, 40 sintered opaque and translucent disc-shaped zirconia, and for the assessment of surface roughness and optical properties, 20 specimens were fabricated and artificially aged in an autoclave for 10 h. The CIE L*a*b* color parameters were measured. The translucency parameter (TP), contrast ratio (CR), opalescence (OP), and color difference against a white (Δ EW) and a black (Δ EB) background were all calculated. The surface roughness (Ra and Rz) was analyzed using a profilometer and the BFS test was performed at a crosshead speed of 1 mm/min. Data were analyzed using two-way ANOVA, t-test, and Mann-Whitney test (α =0. 05). Results: The mean Ra (P=0. 023) and Rz (P=0. 011) significantly decreased after aging. Aging had no significant effect on TP (P=0. 384), CR (P=0. 261), or BFS (P=0. 912). The mean TP values of translucent specimens were significantly higher than those of opaque specimens (P=0. 046). For translucent specimens, the mean OP did not significantly change after aging (P=0. 685) but aging significantly increased the OP of opaque specimens (P=0. 007). The mean Δ EW and Δ EB of translucent specimens were higher than those of opaque specimens (P=0. 044 and P=0. 019, respectively). Conclusion: Although aging affected the OP parameter, other optical properties and also BFS of both zirconia types were not affected by hydrothermal aging. However, the surface roughness of both zirconia types significantly decreased as a result of aging.

Transportation Discrete Network Design Problem (TDNDP) aims at choosing a subset of proposed projects to minimize the users’ total travel time with respect to budget constraint. Because TDNDP is a hard combinatorial problem, recent research has widely addressed heuristic approaches and ignored the exact solution. This paper is going to explore how application of parallel computation can affect the performance of an exact algorithm in TDNDP. First, we show that the Branch-and-Bound (B&B) algorithm proposed by LeBlanc is well adapted to a parallel design with synchronized Master-Slave (MS) paradigm. Then we develop a parallel B&B algorithm and implement it with two search strategies of Depth-First-Search (DFS) and Best-First-Search (BFS). Detailed results over up to 16 processing cores are reported and discussed in an illustrative example of the Chicago Sketch network. The results suggest an almost linear speedup for both strategies which slightly drops as more processing cores are added. When using 16 processing cores the speedup values of 11.80 and 12.20 are achieved for DFS and BFS strategies respectively. Furthermore, the BFS strategy reveals a very fast parallel performance by finding the optimal solution via the minimum computational effort.