This paper examines in detail the little-known Friday Mosque (masjid-i jāmi‘) of Firdaus, located southwest of the Khurasan, which has had a key role in developing Saljuq architecture in the area. The original scheme of the mosque was unclear. The lofty īwān and two flanking dome chambers on the west (qibla) side of the courtyard are the central core of the mosque. The main aim of the article is to analyse the architecture of the mosque and demonstrate its association with the architectural style of the Saljuq mosque in the Khurasan area.  During the conservation and restoration measures in 2006, some fresh materials were unearthed. The new findings shed light on the original features of the mosque and revealed its formation. The paper describes the city's history, defines its architectural characteristics, and then analyses the present information for replying to the research questions. Owing to the outcomes of the archaeological investigation, the study suggests the general scheme of the mosque as a further example of the two- īwān mosque, which may be dated to the late years of the 6th /12th century. Despite the importance of the mosque, no lengthy study has been published about the building. The accurate drawing of the plan and sections of this monument, with the proposal scheme for the reconstruction of the mosque, are being published in this paper for the first time.

The Welded Unreinforced Flange-Welded (WUF-W) connection is one of the most applicable rigid connections used in moment frames. On the other hand, applying built-up box columns is conventional in Iran and Asian countries. Considering the challenges of installing the Continuity plates inside the built-up box columns, developing the seismic design equation of minimum face thickness of box column in the connections without Continuity plates and trying to reach some creative solutions for eliminating the Continuity plates have always been hot topics for researchers, designers, and steel structure industries. It is worth mentioning that due to the lack of use of built-up box columns in European and American countries, European and American standards have not dealt with the criteria of the seismic design of the Continuity plates in built-up box columns. Although the AIJ code has proposed a pair of through diaphragms instead of Continuity plates to solve the challenges of installing the Continuity plates in built-up box columns, and this method has been considered by Iranian researchers, it seems that because of the risk of completely cutting the column section and protruding the Continuity plate from column face level, this method has low chance to be widespread used. Regarding the fact that the behavior of the panel zone of H section and box section columns are different, developing the seismic design equations for minimum thickness of column face in built-up box columns without Continuity plates have been advised in AISC 341-16. The motivation of developing the seismic design equation of box column face thickness increases when considering that 5th draft edition of the 10th part of the Iranian National Building Code (Steel Building Design and Construction) clarifies that all rigid connections of I beam to box columns, regardless of the column face thickness, must have Continuity plates which seems strict. On the other hand, by converting the beam extreme moment to a compression-tension couple force, it seems that the depth of the beam has influence on the nominal capacity of column face resistance.Therefore, in this numerical study, 18 samples have been modeled to investigate the behavior of WUF-W rigid connection to built-up box columns as well as the probable effect of beam depth on the behavior of WUF-W rigid connection of I beam to box columns. The models have been loaded under cyclic loading and monotonic loading corresponding to the AISC 341-16 protocol. The loading has been continued up to 0.06 radian rotation and the frames have been simplified to a console beam and a column. To verify the modeling, the experimental study of Saniee Nia et al. has been used.The results show that although all the models without Continuity plates apparently pass the provisions of AISC 341-16 and the 4th edition of the 10th part of the Iranian National Building Code, more attention to details displays some problems. In all samples without Continuity plates, the column thickness has been almost 25% over designed, to guarantee the appropriate behavior. But focusing on the equivalent plastic strain at the beam flange edge at loading steps shows the disproportionate spread of plastic strain along the beam flange edge. The plastic hinge is located at the end of beam at the intersection of beam and column face and the column face is partially deformed, which is not desirable. The models without Continuity plate have lack of enough rotational stiffness, which does not represent rigid connections but semi-rigid joints. It seems that, unlike what was expected, the beam depth has no obvious effect on the pattern of hysteresis carves of the models without Continuity plates like Eurocode 3. However, by 46% decreasing in beam depth, the equivalent plastic strain at the beam flange edge becomes more uniform up to  55% and the rigidity increases up to 23%. Finally, it seems that increasing the thickness of the box column face will lead to increase the rigidity and therefore, it is recommended to develop the seismic design equations to determine the minimum face thickness of the box column in the connection without Continuity plates. Finally, it is suggested to address semi-rigid connections in the AISC 341 and in the Iranian National Building Code, 10th part.

Precise investigation of the connections in a steel structure is important, and inaccuracy in the design and implementation of connections not only does cause failure in the connection, but also has a devastating effect on other members of the structure. Bolted end plate connections are commonly used in steel structures. There are two types of beam-to-column flange connections, four-bolt and eight-bolt. The four-bolt connection is used for low anchor values and the eight-bolt connection is used for large bending anchor values. In this study, the cyclic behavior of the restrained beam-to-column connections with end plate under cyclic loading has been evaluated. In the calculations, all of the parameters affecting the behavior of this connection have been investigated and solutions are proposed to reach the maximum connection capacity. Since the behavior of this connection depends on several factors, two general models of beam connection to different columns with beams of 30 and 40 cm depth are considered for research purposes. The thickness of end plate, shape of end plate, thickness of the column flange, strength or material of the bolts, the necessity of using Continuity plate, stiffener and doubler plate are among the parameters considered in the analyzes. According to the results of this study, the use of a thin-walled end plate leads to local buckling of plate. The use of Continuity plate is very important and prevents local buckling in the panel zone. Also, in cases where the thickness of the column web is low, the use of a doubler plate will also be necessary. In addition, the use of a stiffener improves the flexural strength of the section.

In this study, an approach to free vibration analysis of thin quadrilateral plates using the generalized differential quadrature method based on the strong version of the governing equation is proposed. Hence, the governing equation of a thin quadrilateral plate is firstly obtained using the Kirchhoff–Love theory of plates (classical theory) to achieve this aim. The well-known differential quadrature method is then utilized to obtain the discretized form of the equations of motion. However, simulation of any arbitrary geometry using conventional Generalized Differential Quadrature Method based on classical theory is impossible. This drawback can be removed by defining the additional degrees of freedom in boundaries. Moreover, the combination of the Refined Differential Quadrature Method with geometry mapping is developed to simulate thin quadrilateral plates. Also, the multi-block or elemental strategy is implemented for problems with more geometric complexities. For this aim, geometry can be divided into several subdomains. Continuity conditions make the connection between adjacent elements at each interface. By establishing the whole discretized governing equations, the free vibration analysis of a thin plate will be provided via the achieved eigenvalue problem. The obtained results are compared and validated with available results in the literature that show high accuracy and a fast rate of convergence.

Background and Aims: Radiographic examination prior to implant placement is often complemented with tomography for location of vital anatomic structures and evaluation of bone volume. The aim of this study was to evaluate the accuracy of Photostimulable Phosphor plate system with that of conventional film-screen in mandibular pre-implant linear tomography Materials and Methods: In this test evaluation study, tomograms of 2 dry human mandibles were taken using the both film-screen and Photostimulable Phosphor plate. 10 sites were selected in each mandible and marked with gutta-percha. Distance of superior border to the mandibular canal and the total height and width of mandible were measured on the tomograms and also on the mandibles after sectioning. The radiographic values were compared with real ones.Results: After correction of tomographic values by the magnification factor of the unit, the mean of absolute differences with reality in linear tomography using film-screen and Photostimulable Phosphor plate for height of mandible were 0.59mm (SD=0.54) and 0.65mm (SD=0.72), respectively. The mean of absolute differences with reality in linear tomography using film-screen and Photostimulable Phosphor plate for width of mandible were 0.34mm (SD=0.33) and 0.31mm (SD=0.33), respectively. In localization of the mandibular canal, the mean of absolute differences with reality were 0.54mm (SD=0.30) and 0.52mm (SD=0.56) for linear tomography using film-screen and Photostimulable Phosphor plate, respectively. In linear tomography using film-screen, 100% of measurements for localization of the canal, 80% of height and 95% of width were within ± 1mm error limits. In linear tomography using Photostimulable Phosphor plate, 75% of measurements for localization of the canal, 75% of height and 95% of width were within ± 1mm error limits. There was no significant difference between linear tomography using film-screen and Photostimulable Phosphor plate in localizing the mandibular canal and height and width estimation (P>0.05).Conclusion: The accuracy of linear tomography using film-screen and Photostimulable Phosphor plate in height and width estimation and localization of the canal is within acceptable limits.

This study attempted to review the articles and explore the gaps and challenges in the areas of resilience, business Continuity, risk, and process safety with the aim of providing several directions for future research to understand different research directions in these areas with different perspectives. In addition, in this study, the relationship of articles in these areas with each other was examined. In this research project, related studies were reviewed and reported to identify presented frameworks, models, and methods for them. In the first phase, the articles were divided into three categories according to their similarity, namely “maximizing the value of business Continuity and resilience, ” “maximizing process safety and the effect of risk and resilience factors, ” and “minimizing risk and effect of uncertainty. ” In the second phase, the appropriate conceptual frameworks titled “research house” based on resilience, business Continuity, and risk categories were created for each category. In the third phase, 22 closed codes were obtained by carefully reviewing the articles, and their co-occurrence network was investigated. The main findings of this article were categorizing the studied articles, providing conceptual frameworks resulting from article analysis, and presenting a conceptual model.