Sharif Digital Repository

On-time delivery of network flows is crucial to ensure the quality of service of deadline-constrained applications. Today, real time applications have various uses in multimedia communications, the Internet of Things (IoT), and 5G (5th generation mobile network) technology. In Software Defined Network (SDN) architecture, the controller has a global view of the network. Hence, it is possible to enrich the features of the controller and/or forwarding devices to support real time communication. In this paper, we propose a firm real time software-defined approach (FRT-SDN) for real time communication and present a novel solution for the real time forwarding/routing of time-sensitive applications... 

This paper proposes a novel and efficient real time network architecture, named RT-TelSurg, for one of the most appealing tactile Internet applications, i.e., Telesurgery. In telesurgery, the patient's vital signs and status and the required robotic commands during the surgery should be received on time. Otherwise, the life of the patient or the safety of the operation is endangered. Hence, transmitted packets should meet their respective relative deadlines. Software-defined networking is a relatively new architecture for computer and telecommunications networks in which the network control plane is separated from the data plane. One way to achieve real time telesurgery is to employ cloud... 

Software-defined network (SDN) is an emerging network architecture in which the network control task is separated from packet forwarding. This architecture can be considered as a suitable infrastructure for fifth-generation mobile network (5G) and Internet of things due to its flexibility and dynamism. In real-time networks, time-sensitive packets that miss their deadlines are considered useless or less worthy. As with traditional networks, SDN is expected to support real-time communications and handle a variety of failures (including local controller, switch, and link failures) simultaneously. This study focuses on real-time communication of time-sensitive applications that operate on... 

This paper presents a novel, energy-efficient routing approach for underwater sensor networks in tsunami early warning. Our system utilizes sensor nodes equipped with piezoelectric energy harvesting to extend network lifetime and stability. Continuous sensing is replaced with a duty-cycled approach to conserve energy, where the ocean surface is divided into regions and sensor nodes are grouped. These groups become active at designated intervals, while others remain dormant. The system leverages satellite networks to complement the underwater sensor network, enabling collected data to reach the central hub of early warning systems. A statistical analysis assigns scores to potential routes... 

Ground Source Heat Pumps (GSHP), as a renewable source heating, ventilating, and air conditioning (HVAC) technology, has the highest energy efficiency among different heat pump types. One of the major drawbacks of GSHPs is the long-term ground temperature variations as a result of heat accumulation or depletion in the ground. This contribution puts forward a novel ground thermal recovery system for horizontal ground heat exchangers in a hot climate. The proposed recovery system consists of open-loop horizontal Ground-Air Heat Exchangers (GAHEs) that are buried between the horizontal Ground-Water Heat Exchangers (GWHEs). A fan supplies ambient air to the GAHE pipes when the soil around GWHE... 

The capacity factor is an important wind turbine parameter which is ratio of average output electrical power to rated electrical power of the wind turbine. Another main factor, the AEP, the annual energy production, can be determined using wind characteristics and wind turbine performance. Lower rated power may lead to higher capacity factor but will reduce the AEP. Therefore, it is important to consider simultaneously both the capacity factor and the AEP in design or selecting a wind turbine. In this work, a new semi-empirical secondary capacity factor is introduced for determining a rated wind speed at which yearly energy and hydrogen production obtain a maximum value. This capacity factor... 

Existing algorithms based on scale invariant feature transform (SIFT) and Harris corners such as edge-driven dual-bootstrap iterative closest point and Harris-partial intensity invariant feature descriptor (PIIFD) respectivley have been shown to be robust in registering multimodal retinal images. However, they fail to register color retinal images with other modalities in the presence of large content or scale changes. Moreover, the approaches need preprocessing operations such as image resizing to do well. This restricts the application of image registration for further analysis such as change detection and image fusion. Motivated by the need for efficient registration of multimodal retinal... 

In this study, the authors investigate the performance of optical code-division multiple access (OCDMA) systems with belief propagation (BP)-based receivers. They propose three receivers for the optical fibre channel that provide a trade-off between detecting complexity and system performance. The first proposed receiver achieves a performance very close to the so-called known interference lower bound. The second receiver exhibits a considerably less complexity at the expense of a slight degradation in performance. They show that the third BP-based receiver, which is a simplified version of the second receiver, is surprisingly the same as the so-called multistage detector in OCDMA systems.... 

Alkaline flooding is one of the newest chemical enhanced oil recovery (EOR) methods. Alkaline generates in situ surfactants when in reacts with acid content of the oil. This economic surfactant generated in oil-water interface, reduces interfacial tension (IFT) significantly that leads to increase in oil recovery by extracting oil from tiny pores. In this study, three alkaline i.e. Na2CO3, NaOH and KOH in various concentrations were flooded in a glassy micromodel to detect displacement mechanisms and compare oil recovery. According to the results, increase in alkaline concentration leads to increase in recovery. However, in this case, alkaline type does not play a significant role. In... 

Today, the production of energy and electricity is one of the major concerns of mankind. Electricity generation by solar energy is considered as one of the alternatives to fossil fuels. Solar chimneys mechanism is based on a natural phenomenon. In this process the solar energy heat up the earth's surface and the surrounding air. Due to the density difference between cold air and warm air, heated air ascends and causes air circulation. In this study, mathematical modelling of solar chimney and governing equations of this system will be discussed. In order to validate the numerical results, upwind velocity in chimney has been compared with a reliable reference results. As well as, the... 

FlexRay communication protocol is expected becoming the de-facto standard for distributed safetycritical systems. In this paper, transient single bit-flip faults were injected into the FlexRay communication controller to categorize and analyze the activatedfaults. In this protocol, an activated fault results in one or more error types which are Boundary violation, Conflict, Content, Freeze, Synchronization, and Syntax. To study the activated faults, a FlexRay bus network, composed of four nodes, was modeled by Verilog HDL; and a total of 135,600 transient faults were injected in only one node, where 9,342 (6.9%) of the faults were activated. The results show that the Synchronization error is... 

Nowadays, communication protocols are used in safety-critical automotive applications. In these applications, fault tolerance is a main requirement and the existence of single points of failure is a serious threat to system failures. Among the communication protocols, FlexRay is expected to become the communication backbone for future automotive systems. In this paper, we identify single points of failure in the FlexRay protocol by injecting a total of 135,600 single-bit transient faults into all accessible registers of the FlexRay communication controller. The results showed that about 1.2% of all injected faults caused the controller to freeze immediately. Based on these results and... 

Nowadays, distributed embedded systems are employed in many safety-critical applications such as X-by-Wire. These systems are composed of several nodes interconnected by a network. Studies show that a transient fault in the communication controller of a network node can lead to errors in the fault site node (called original errors) and/or in the neighbor nodes (called follow-up errors). The communication controller of a network node can be halted due to an error, which may be a follow-up error. In this situation, a follow-up error leads to halt the correct operation of a fault-free controller while the fault site node, i.e. the faulty controller, still continues its operation. In this paper,... 

FlexRay communication protocol is expected to become the de-facto standard for distributed safety-critical systems. This paper classifies the effects of transient single bit-flip fault injections into the FlexRay communication controller. In this protocol, when an injected fault is activated, this may result in one or more error types, i.e.: Boundary violation, Conflict, Content, Freeze, Synchronization, Syntax, and Invalid frame. To study the activated faults, a FlexRay bus network, composed of four nodes, was modeled by Verilog HDL; and a total of 135,600 transient faults was injected in only one node, called the target node. The results show that only 9,342 of the faults (about 6.9%) were... 

It is now widely believed that FlexRay communication protocol will become the de-facto standard for distributed safety-critical automotive systems. In this paper, the fault sensitivity of the FlexRay communication controller registers are investigated using transient single bit-flip fault injection. To do this, a FlexRay bus network, composed of four nodes, was modeled. A total of 135,600 transient single bit-flip faults were injected to all 408 accessible single-bit and multiple-bit registers of the communication controller in one node. The results showed that among all 408 accessible registers, 30 registers were immediately affected by the injected faults. The results also showed that... 

We report a new method of growing Mn-doped CdS (CdS:Mn) nanoparticles in an aqueous solution at boiling temperature. The idea is to use precursors that react only at high temperature, in order to gain crystalline luminescent nanoparticles. CdSO4, Mn(NO3)2 and Na 2S2O3 were used as the precursors, and thioglycerol was employed as the capping agent and also the reaction catalyst. Na2S2O3 is thermally sensitive and it releases S2- ions upon heating. The CdS:Mn nanoparticles obtained are about 4 nm in size and show both cubic and hexagonal crystalline phases with a ratio of 35% to 65%. The luminescence of nanoparticles contains a peak at 580 nm, which is related to Mn2+ ions. Prolonged reaction... 

In this paper, we consider a code-shifted reference (CSR) for the previously introduced internally coded time hopping UWB communication systems in order to avoid channel estimation. We evaluate the performance of our proposed scheme and compare the results with those of the uncoded coded-shifted reference (CSR) UWB system. Our numerical results show the substantial performance improvement when using the proposed scheme compared to the uncoded CSR system. ©2008 IEEE  

CdS nanoparticles were grown using CdSO4 and Na 2S2O3 as the precursors and thioglycerol (TG) as the capping agent. TG was shown to exhibit a catalytic role in the reaction and also acted as a capping agent. It was demonstrated that size growth is linearly related to the temperature of the reaction, i.e.the sizes can be controllably adjusted by temperature. The crystalline phase of the nanocrystals was also dependent on the temperature of growth: higher temperature favours the cubic phase. The pH also plays an important role in nanoparticle growth, as lower pH leads to a higher release rate of sulfur species. At pH as high as 10, the growth rate remains slow even at boiling temperature. This...