Sharif Digital Repository

The Translation Lookaside Buffer (TLB) is a CPU cache that stores translations of virtual to physical addresses. Each CPU core contains its own TLB, and the consistency among these TLBs is not enforced by hardware but is delegated to the software. This task is performed via a “shootdown,” wherein one core sends a TLB invalidation command to another core using an Inter-Processor Interrupt (IPI). The current implementation of this consistency mechanism imposes significant overhead and latency. Furthermore, with the discovery of various CPU vulnerabilities in recent years, TLB security has also become a major concern. To mitigate TLB overhead, past research has explored two main approaches:... 

Walking-robots have received much attention because of the variety of motion maneuvers they can produce and the many applications they have in various areas including rehabilitation. One of these maneuvers is running. In this study, a time-invariant controller is designed to dynamically stabilize a five-link and a seven-link running-robots in two dimensions. In the simulation of the seven-link model, an attempt has been made to measure the impact of the circular foot on the stepping pattern. Also, it is tried to present a dynamically simple model similar to the geometry of the human body. Simulations are performed in MATLAB software. The running is modeled with three phases of stance, flight... 

Predicting the evolution of viruses is vital in controlling, preventing, and treating diseases. Mutations that evade the host immune system can propagate and persist through generations, making it crucial to anticipate and combat them effectively. The 1918 H1N1 pandemic serves as an example of the devastating impact of pandemics caused by viral mutations. By predicting mutations in advance, we can identify potential future pandemics and take effective preventative measures to mitigate their impact. Proteins play a vital role in the functioning of viruses. They are involved in various processes, such as replication, transcription, and host cell invasion. Any changes in the protein sequence... 

Due to unusual response of structures of buildings with irregularity in their architecture to dynamic excitations, to have a comprehensive knowledge of their behavior during earthquakes is of utmost importance. Building irregularities are in general divided into two major categories, namely Irregularity in Plane and Irregularity in Elevation, and one of the forms of the latter is where there is a split in the levels of the building. In this work, through a series of case studies, the effects of P- phenomenon on the behavior of steel split-level building structures were studied. 5, 10 and 15 story buildings with 5 and 6 bays, and level splitting of 30, 60, 90, 120 and 150 cm were studied. All... 

Mesoscopic hydrodynamic equations are solved employing a VOF based method to investigate the equilibrium shape of nanodroplets positioned over various topographic geometries of the supporting substrate for three-dimensional systems. By taking into account liquid-liquid and liquid-solid interactions a complex distribution for inter-molecular forces over the substrates (the disjoining pressure) is observed. In this research we show that motion of nanodroplets not only caused by contact angle difference in drplets two sides, but also depend on disjoining pressure parameters.Geometries with increasing complexities, from wedges to three dimensional edges and wedges, were explored with the main... 

Observations made after previous earthquakes have shown the crucial role of irregularities in initiating damage in buildings with irregularity, either in Plan or in Elevation. Since in existing Building Codes, there is no provision for the distribution of the Equivalent Static Loads for such buildings, designers have no option but to resort to Dynamic Analysis. In this work, the seismic behaviour of a group of two-dimensional steel building structures with irregularity in elevation, namely Split-Level buildings, was studied. The studied structures consist of a series of 5- and 15-storey frames having two parts with splitting distance of 150 cm. Both, moment-resisting and braced frames were... 

With the road transportation vehicles being widely used, concerns have been increased regarding their unwanted effects. Air pollution, climate change, and oil supply security are among these effects. Many alternative fuels and propulsion systems have been proposed to be used instead of conventional ICE vehicles in recent decades. This project intends to conduct a Techno-Economic comparison between different vehicle powertrains so as to select the suitable choice to substitute conventional ICE vehicles. The vehicle options are ICE vehicles using both gasoline and CNG as fuels, Hybrid Electric Vehicles (HEVs), Plug-in Hybrid Electric Vehicles (PHEVs), and Electric Vehicles (EVs). The amount of... 

Base plates as the connecting components of steel structures to their foundations, have a crucial role in the behavior of these structures. In order to limit the thickness of base plates hence their cost within reasonable values, various types of attachments (stiffeners) are normally added to them. In this project 6 different configurations, Models, for the base plate and its attachments were considered and studied through finite element analysis. Each Model was studied under the combination of biaxial moments and a range of compressive loads including 0, 0.05 P/Py, 0.10 P/Py and 0.15 P/Py, where Py is the plastic load of the column. The moment-rotation curves of all models under various... 

Reducing air pollutant emissions from vehicles is a difficult and time consuming procedure which needs utilizing of modern emission control equipment and setting strict regulations for car factories and drivers as well. How efficient these policies are and proposing operative solutions for air quality improvement depend on developing a sustainable model which is used in vehicle emission predictions and their share in total emissions. Emission factors are not constant values as they can be affected by various operational and ambient parameters. Development of Emission inventories calls for a huge number of measurements using different vehicles in diverse conditions. Thus, recognition of...