Sharif Digital Repository

Natural language generation is one of the burgeoning areas of Nautural Langauge Processing/Computational Linguistics in which the primary concern is to automatically generate sentences in human languages. Based on the type of the input they receive, NLG systems can be divided into two categories: text-to-text and data-to-text. Systems of the first type are usually a part of machine translation systems. The latter type, which is the subject of the current research, deals with language generation based on inputs other than raw text, such as databases, images, videos, audio and so on. This project is an attempt to create an image-to-text system. This is the first research on data-to-text NLG... 

Blockchains are not scalable by design, and it is known to be the most important barrier in the way of development of these systems. One of the main approaches to this problem is sharding, that is under development in industry and academia. Sharding scales the system up by reducing redundancy, that makes blockchains vulnerable in terms of security. In this paper, we will study the effect of sharding on availability of these systems, and will show that sharding can magnify the unavailability of the service, and introduce an adversary threat model that takes real concerns of availability in today’s Internet like DoS attacks into account. We also introduce a basic unavailability-resistant... 

In the near future, we will see a new generation of cellular networks called 5G. Due to the growing number of users and applications, cloud computing does not provide users needs. Edge servers can be used at radio base stations for this purpose. Edge server is a limited processing unit that allows users to perform their processing operations as close as possible. Therefore, the distance between the user and the service will be reduced and as a result the response time is greatly decreased.Cloud-based services are supported by specific software that are deployed in a virtual machine. The number of virtual machines of different applications is fewer than the number of edge servers in the... 

The leaching process is the first stage in the process of extracting uranium out of the ore. The leaching, based on the used material is divided into two main methods of acidic and alkali leaching. Each of these two techniques have their own pros and cones. It is notable that due to lower costs, and faster kinetics, the acid leaching is the first option of the mines unless the percentage of carbonates (and the other acid-soluble materials) in the ore are too high that makes this process uneconomical because of higher acid consumption. The kinetics of the acid leaching of the uranium depends on various parameters such as acid concentration, the particle size, exposure time and the temperature... 

According to the increasing amount of data exchanged among data centers, the need for speeding up and bandwidth and reduced power consumption has been increased. The information show that about 77% of the data is moved into the data centers. On the other hand, 10% of data center’s power consumption is used to data transmission. Improving the interconnection network of data centers can play an important role in reducing power consumption and speeding up. In recent years, optical interconnects have gained attention as a promising solution. Nevertheless, offering an all-optical and efficient architecture is an important issue. In this study, we intend to provide a multi-stage, all-optical... 

Although cloud porcessors have lots of benefits, they have brought new challenges for designers; one of these issues, is information leakage through Timing Channel Attack in shared hardware resources. Among these shared resources, main memory controller is less understood. Also applying timing channel protection technquies to shared memory controller, in comparison with other parts such as NoC, caches, etc, can impose high performance overhead to system throughput. Temporal Partitioning (TP) is the baseline secure scheduling algorithm that was proposed for cope with timing channel attack in shared memory controller; but beside this protection, TP compels high performance degradation. In this... 

In recent years, the usage of Internet bandwidth has been increased by emerging applications such as Video on Demand (VoD).As the popularity of VoD increases among the Internet users, some new problems like bandwidth limitations and congestion embark. For solving mentioned problems, Content Delivery Networks (CDN) has been introduced. Using CDN approaches either in ISP or organization is also known as Telco CDN. Generally implementing CDN approaches to process all requests either in ISP or organization can cause bottleneck. On the other hand, Software Defined Networks (SDN) could bring us new tools and opportunities which enables us to implement novel methods to confront these problems.... 

Software Defined Networking (SDN) is an emerging paradigm which makes the network programmable by separating the control plane from data plane and makes both planes to work independently. There is a centralized controller and a programmable data plane in these networks architecture and forwarding data packets is realized by programming the data plane via an open interface called OpenFlow. OpenFlow is a communication protocol between control and data planes. The centralized architecture of these networks provides a global view of the underlying network to upper applications and brings numerous advantages such as routing, traffic engineering and QoS control. Despite these advantages there are... 

The daily growth of cloud computing usage for data based applications and Internet services has caused many challenges in the sense of storage cost, data access performance, QoS provision such as availability, scalability, pay-as-you-go model conformation and etc. Data replication is one of the most important mechanisms for data management in distributed systems. It creates some replicas of data and distributes them to the network. The number of replicas, the time for creating a new replica, the way of their distribution among the nodes and replica replacement strategy in the case of storage unavailability are some important challenges in data replication context. Replication is extensively... 

In the Pay-TV industry, it is necessary to limit access of unauthorized users. Conditional Access System (CAS) is the solution. In the Pay-TV, the ability of instant join and leave operation is desirable for users. On the other hand, this characteristic is in contradiction with growth of user number.
Previous proposed conditional access systems address the requirement of pay-TV from several aspects. Key distribution management is on of them which plays a key role in the security and efficiency of a conditional access system. Re-examining the process of key distribution management make it possible to find a way to provide a greater flexibility for the users.
The purpose of this... 

Resin In Pulp(RIP) is One of the most important processes for separation of uranium from ore while concentration of uranium in ore is low , based on adsorption of uranium that exist in the slurry on onion exchanger resins .uranium ore is dissolved in sulfuric acid and slurry that contain uranium is produced,then this slurry enter stirred reactors and adsorption process is performed.RIP are accepted universally and now adays countries such as canada,south africa and australia use this process when concentration of uranium in slurry after leaching process is 100-500 ppm.in iran also this process is performing in ardacan-saghand mine.Kinetic of adsorption process in stirred reactors has been... 

One of the main uranium separations of ore that uranium percent application of enhanced design strategies in the industrial cracking furnaces are of practical interest for oil, gas and petrochemical industries. For such engineering purposes the exact simulation of temperature, species concentration and flow fields in the furnace is essential. In this paper, a study was performed to simulate 3D flue gas flow pattern, temperature and species concentration field in the radiation section of an industrial cracking furnace using the computational fluid dynamics (100-500) ppm technique. The steady-state Reynolds Averaged Navier–Stokes (Resin in pulp)equations were solved, in a finite volume scheme,... 

As the number of processing cores on a single chip continues to grow, the need for a high band width, low power communication structure, will be the most important requirements of next generation chip multiprocessors. Today, a major part of power consumption in multi core architectures belongs to interconnects. Due to these facts, reducing consuming power, as well as supporting high performance, is concerned in these architectures. The concept of “network-on-chip” emerged to improve the performance of CMPs. But now a day, considering the circumstances of power budges, it’s incapable of presenting new strategies to decrease consuming power and delay. However, optical interconnects have the... 

With increasing number of processors on a chip, the role of interconnections becomes more important in both power consumption and bandwidth. As a result, in MultiProcessor System-on-Chip architectures, the design constraints will shift from "Computational Constraints" to "Communicational Constraints". Nowadays, optical information transfer is introduced as a suitable substitution for electrical interconnections in chips, which can eliminate their problems. Many different optical networks have been presented so far. These networks can be divided into two subcategories. Networks of the first category use an electrical infrastructure as well as optical one. Hence, the scalability of scheme is... 

As the number of processing cores on a single chip continues to grow, the need for a high bandwidth, low power communication structure, will be the most important requirement of the next generation chip multiprocessors. Today, a major part of power consumption in multicore architectures belongs to interconnects. Due to these facts, reducing power consumption, as well as supporting high performance, is of major concern in these architectures. Optical interconnects have the potential to replace electrical wires to solve the bottleneck of communications in integrated circuits. Various routers and architectures with different points of view, have been recently designed considering existing... 

Hybrid CDN-P2P architecture has been introduced to combine scalability advantage of P2P and reliability of CDN networks. Although it has been proved that CDN-P2P is more efficient than other architectures for live video streaming, there is still the question, “How is it possible to be more efficient in providing higher service quality?” Quality degradation in P2P and Hybrid CDN-P2P is mainly connected to the lack of exploiting role of peers’ heterogeneity in the system. Most of currently deployed live video streaming systems don’t adapt to bandwidth of the peers and just send one version of video to all users. To tackle this issue, many researches combine P2P solution with scalable video... 

This researⅽh investigates the perforⅿanⅽe of epiⅾeⅿiⅽ routing، in ⅿobiⅼe soⅽiaⅼ net−works (ⅯSNs)، whiⅽh ⅿakes use of the store−ⅽarry−forwarⅾ paraⅾigⅿ for ⅽoⅿⅿuni−ⅽation. Reaⅼ−ⅼife ⅿobiⅼity traⅽes show that peopⅼe have skeweⅾ ⅼoⅽation visiting pref−erenⅽes، with soⅿe pⅼaⅽes visiteⅾfrequentⅼy anⅾ soⅿe others infrequentⅼy. In orⅾer to ⅿoⅾeⅼ epiⅾeⅿiⅽ routing in ⅯSNs، we first anaⅼyze the tiⅿe taken for a noⅾe to ⅿeet the first noⅾe beⅼonging to a set of noⅾes restriⅽteⅾ to ⅿove in a speⅽifiⅽ subarea. Af−terwarⅾs، two networks are ⅽonsiⅾereⅾ. For eaⅽh network، a ⅿonoⅼithiⅽ stoⅽhastiⅽ re−warⅾ net (SRN) is proposeⅾ to evaⅼuate the ⅾeⅼivery ⅾeⅼay anⅾ the average nuⅿber of transⅿissions unⅾer... 

Recently, advances in the fabrication and integration of sensing, communication technologies and economical deployment of large scale sensor networks which are capable of large scale target tracking, become possible.therfore, the wireless sensor networks are a fast growing and marvelous research area that has attracted considerable research attention in the recent past. The creation of large-scale sensor networks interconnencting several hundered to a few thousand sensor nodes opens-up several wide range of application and technical challenges. Sensor nodes have been deployed to play significant roles in battlefield, disaster-prone area, traffic control, habitat monitoring and intruder... 

Perovskite solar cells with 25.5% efficiency and fast and cheap manufacturing process are among the most promising technologies in this field to replace silicon cells. Despite the challenges of stability and toxicity to these cells, their manufacturing technology has recently shifted to the development of large-scale manufacturing methods in module dimensions. In the present study, the fabrication of perovskite cells in large dimensions to achieve the perovskite module has been aimed and studied that to achieve this, the method of large-scale spraying and printing using the vacuum system was used to create cell-forming films and, consequently, to make the final cell and module. To... 

Simulation of biophysical neural networks enables the interpretation and integration of fast-growing and different experimental datasets. The widely used NEURON simulator allows molecular-to-network simulation. However, it is still a very hard challenge to create large-scale models and operate parallel simulations applying NEURON. SUNY Downstate developed the NetPyNE means networks using Python and NEURON, which was funded by the New York State Department of Health and some other institutions. NetPyNE is a Python-based tool that enables the development of data-driven multi-scale network models in NEURON through both programmatic and graphical interfaces. It is a powerful tool for parallel...