Today, there is an increasing interest in use of seismic isolation to protect the structures against earthquakes. The most common type of seismic isolation is called base isolation, in which the isolation layer is installed under foundations to separate the structures from the ground and reduce the earthquake forces. However, the use of this type of seismic isolation faces some difficulties such as construction in congested urban areas or construction of near sea structures. Furthermore, for seismic retrofitting of existing buildings, the installation of the isolation under foundations is difficult or even impossible; so, it needs to be located on the middle Floors of the buildings. The method of isolation design is called Floor or middle story isolation. Despite the advantages of seismic isolations, they have some limitations such as instability in large deformations, residual displacement, and the need for replacement after severe earthquakes. The use of Shape Memory Alloys (SMA) regarding their unique properties is considered as an appropriate solution to overcome the above problems. These smart materials show high strength and strain capacity, high recentering ability, and high resistance to corrosion and to fatigue. The purpose of this study is to investigate the effect of combination of middle story isolation utilized by Natural Rubber Bearing (NRB) and iron-based shape memory alloys in steel structures and to compare the performance of such structures with and without the presence of the shape memory alloy in the middle-story isolation system. Then, a three-story steel structure has been modeled and evaluated. For this purpose, a structure with Floor isolation and iron-based shape memory alloy was modeled in OpenSees computer program. The structures were then subjected to seismic loading. The results were presented in the form of story drift, Floor acceleration, Floor shear forces, and base shear. The outcome of this research showed that the use of these alloys in the middle-story isolation reduced the overall base shear and Floor shear forces. The overall story drift, Floor acceleration and displacement are reduced; with the exception at the isolation level. Thus, utilizing the natural rubber bearing isolator along with the iron-based shape memory alloy can be considered as a desirable system for the seismic protective design of buildings.

Mass isolation is a method of structural vibration control against environmental loads such as strong earthquakes. Buildings with local isolation systems are a practical method of mass isolation. These buildings can be non-proportionally damped systems. Available methods for dynamic analysis of these buildings are complex and time-consuming. In this paper, the concept and efficiency of these buildings at seismic response reduction is examined. A simple method for their dynamic analysis is introduced. Proof of the accuracy of the method is also presented.

Floor isolation technique is considered as a new approach in seismic design of structures in which the mass of building at each Floor is isolated from the main structural system via seismic isolators. In this case, during earthquake actions, large relative movement between isolated Floors and the main structural system at each Floor level would be expected. In the current work, numerical studies have been carried out on a typical Floor isolated building to investigate the role of displacement constraints (Stoppers) in limiting the gap between the Floors and the structural system during seismic actions. A ten-story steel frame structural system located on stiff soil subjected to far-field earthquakes was selected for parametric study in this work. The structure has been proportioned in three different configurations, not isolated, Floor isolated and Floor isolated equipped with Stoppers. Since using Floor isolation improves the structural performances of the system, a fourth configuration for the same structural system with 18% reduction in steel consumption is also taken into consideration. This structure was deliberately proportioned to provide the state of comparable seismic performances between the isolated structure and the nonisolated one. Direct time integration analyses using seven scaled bi-directional earthquake records have been carried out on the same structural system for all its configurations. According to the results of this study, Floor isolation is quite effective in improving structural performances of the system. In fact, on average, Floor isolation causes significant reduction on lateral displacement of the structural system (more than 50%) if it compares with the nonisolated one. The results also show the benefit of using Floor isolation technique in design of structural system by decreasing the construction cost of the building (18% reduction in the weight of structural material) if a comparable seismic performance with the non-isolated structural system is required. It should be noted that, improving in seismic performances of the building or reduction in its construction cost comes in the expenses of large relative movement of isolated Floors with respect to the main structural system. In the example used in this study such relative movement (average of seven earthquakes) reached to the level of 0. 1 meter. However, in one of those earthquakes (Imperial Valley, 1979) this relative movement has soared up to 0. 19 meters. Such large relative movement needs complicated non-structural detailing for the building assembly and expensive seismic isolators. To deal with this problem, displacement constraints have been provided for the Floor movement using elastic Stoppers. The gap between Stoppers and the Floor system is chosen at 0. 1 meter to limit the Stopper’ s functionality in structure only to the case when the system is subjected to large earthquakes. The results of parametric studies on the system with reduced structural weight (configuration fourth) shows a reasonable reduction in relative displacement between Floors and the main structure in case of using Stoppers. These results were obtained using nonlinear time integration analyses on the structural system subjected to Imperial Valley earthquake record. According to these results, while Stoppers can reduce the relative movement between Floors and the structural system to about 35%, they considerably add to the acceleration of the Floor system (up to twice for the isolated structure at the roof level). In addition, the results also show using Stoppers may add to the inter story drift limit of the structure (up to 20%). These shortcomings in using Stoppers in this work can possibly be reduced using Stoppers with different arrangement and sophisticated characteristics.

This paper proposes a 2.4 GHz active mixer without passive inductor for the transceiver system. Taking into account the design requirements of the mixer, a double-balanced down-conversion structure with active inductor and negative resistance is designed. The proposed mixer with 130 nm CMOS technology is designed and simulated using Cadence software at 1.5 V supply voltage. Although we had to compromise conversion gain with linearity, we were able to achieve very high conversion gain with average linearity. Based on the results of post-layout simulations, the conversion gain of 27.57 dB, IIP3 equal to -7.88 dBm, 1-dB compression point equal to -17.34 dBm and IIP2 equal to 44.22 dBm with power consumption of 2.5 mW was obtained for the proposed mixer. The chip size without input and output pads is 95.18 µm × 117.68 µm, which leads to a chip area of 0.0112mm2.

The present paper investigates the effect of soil-structure interaction on the seismic behavior of base-isolated frames under near and far-fault earthquakes. For this purpose, the nonlinear time history results of 1, 4 and 8-story base-isolated frames are compared with corresponding fixed base ones. ABAQUS finite element software is used for numerical modeling on which time history analyzes are performed.

This study investigates the production of Flooring from oriented strand board (OSB) made with urban and garden tree pruning waste, with the aim of reducing urban management costs and creating stable income. Two types of directional chipboard Flooring were produced: "B, " using 45% garden tree pruning and 55% urban tree pruning, and "T, " using 100% garden tree pruning and urea formaldehyde resin. The study varied the percentage of resin in two levels (10% and 12%) and the percentage of cake moisture in two levels (12% and 14%). Several tests were conducted based on international Flooring standards, including surface wettability, free fall impact resistance, surface hardness, concentrated loading, and abrasion resistance. The results showed that OSB type T Flooring had less moisture absorption and shrinkage in the surface wettability test, while T-type OSB Flooring had better surface hardness, wear resistance, and resistance to force in the concentrated load test at point 2 compared to other types. The study concludes that producing Flooring with 100% garden tree pruning chips, 12% urea formaldehyde resin, and 14% cake moisture can yield the best results. Based on the results, it is possible to use all four types of finished Flooring in humid climates and high-traffic environments such as industrial buildings, companies, and residences. It is suggested that the biodegraded pruning of trees be used in the production of other engineered boards to preserve forests as the source of oxygen and habitat for animal species.

Background & Objective: Pelvic Floor disorders (PFDs) are common devastating situations among women globally. The present study aimed to evaluate the clinical efficacy of radiofrequency (RF) on pelvic Floor distress, restoration, and sexual function among women with PFDs. Materials & Methods: This pre-post intervention study was performed on forty-three women with PFDs, who referred to a teaching pelvic Floor clinic. Patients underwent RF three times fortnightly. Women were examined at three time points of baseline, one month post-intervention, and in a three months follow-up. In addition, a biofeedback evaluation was performed by a physiotherapist at the first session and follow-up. All women were asked to complete the Female Sexual Function Index and Pelvic Floor Distress Inventory questionnaires at the first session and in follow-up assessments. Descriptive statistics, the paired samples t-test, and the Friedman test were used to analyze the data. Results: The mean and standard deviation of the age and gravidity of participants were 40. 3±, 8. 01 years and 2. 65±, 1. 3, respectively. We observed that 81. 4% of women had a history of vaginal delivery. A significant improvement was found in the levator muscle tonicity by manual examination in the three-month follow-up (P<0. 001). Moreover, maximal pelvic Floor contraction measured by biofeedback improved (P=0. 075). There were significant improvements in female sexual function and pelvic Floor distress, including pelvic organ prolapse, colorectal-anal distress, and urinary distress after RF therapy (P<0. 001). Conclusion: The findings of the current investigation showed that RF could be applied for pelvic Floor restoration and is likely to improve sexual function and pelvic Floor distress.