Controller placement mechanism in software defined network using k-median algorithm

Software Defined Network (SDN) decouples the control plane and the data plane, and moves the control plane to an external entity. The decoupling raises many challenges, and one of these is the placement of the controller in the network. This study aims to address controller placement problem in SDN. k-median is used to determine the placement of the controllers, and the placement with the lowest value of average propagation latency will be chosen. The placement compares two resulted placements. First, comparing to greedy algorithm that computes the combinations according to the order of the nodes and calculates the best values at each step, and the results were identical. The second comparison was with the combinations results from considering the placement from specific nodes, and the results showed that it gives higher results than depending on the lowest values resulted from the k-median. Finally, three controllers are chosen as the minimum number of controllers, they were evaluated in terms of delay and load, and as results it was found that three controllers are suitable number of controllers as long as there is no delay or load in the network. Combining the two algorithms for finding the placement and the number results in Controller Placement Mechanism (CPM

Experimental Study of Oxidation, Ignition and Combustion of Aluminum Based Nanomaterials

PhdAluminum based reactive nanomaterials have extensive applications in many fields including solid propellants, pyrotechnics, and catalytic reactions. One recent example is the novel concept of using nanostructured energetic particles for energy storage where the controlled exothermic reaction is the key to control the energy release process. It is of primary interest to understand the thermodynamics, kinetics, morphological and structural properties of these particles during the exothermic reaction. While the physiochemical properties of the monometallic powders are determined only by their size, the properties of bimetallic nanoalloys can be also engineered by their constituent compositions. This thesis conducts a systematic experimental investigation of the oxidation, ignition, and combustion of nano aluminum particles (nAl) and nanoalloys such as nanoscale aluminium-copper (n-AlCu) and aluminium-zinc (n-AlZn). The oxidation experiments are conducted by a TGA/DSC system with detailed characterisation of particles before and after the experiments by scanning electron microscopy (SEM), transmission electron microscopy (TEM), the Nanosizer, Brunauer–Emmett–Teller (BET), energy dispersive X-ray spectroscopy (EDS) and powder X-ray diffractionmetry (XRD). In the TGA/DSC analysis, nanomaterials are oxidized either at constant temperature or under different heating rates in the controlled atmosphere of air or nitrogen. A unique early ignition reaction is observed at the high heating rates for nAl and n-AlCu, which is associated with the effect of polymorphic phase transformation of the alumina shell and the early melting of the aluminum core. Different to the conventional shrink-core concept, hollow structures, i.e. nanoholes, in the central regions of nAl are observed and a phenomenal model is proposed. The comparison of the thermal-chemical characteristics of different nanomaterials reveals some unique 5 features related to nano-alloys such as increased reactivity. A preliminary combustion experiment on feeding nanoparticles in a methane stream is performed with a Bunsen burner setup, where the burning characteristics of different nanoparticles are analysed.University of Engineering and Technology Lahore, Pakista

Routing schemes in FANETs: a survey

Flying ad hoc network (FANET) is a self-organizing wireless network that enables inexpensive, flexible, and easy-to-deploy flying nodes, such as unmanned aerial vehicles (UAVs), to communicate among themselves in the absence of fixed network infrastructure. FANET is one of the emerging networks that has an extensive range of next-generation applications. Hence, FANET plays a significant role in achieving application-based goals. Routing enables the flying nodes to collaborate and coordinate among themselves and to establish routes to radio access infrastructure, particularly FANET base station (BS). With a longer route lifetime, the effects of link disconnections and network partitions reduce. Routing must cater to two main characteristics of FANETs that reduce the route lifetime. Firstly, the collaboration nature requires the flying nodes to exchange messages and to coordinate among themselves, causing high energy consumption. Secondly, the mobility pattern of the flying nodes is highly dynamic in a three-dimensional space and they may be spaced far apart, causing link disconnection. In this paper, we present a comprehensive survey of the limited research work of routing schemes in FANETs. Different aspects, including objectives, challenges, routing metrics, characteristics, and performance measures, are covered. Furthermore, we present open issues

Atraumatic Splenic Rupture after Myocardial Infarction

Atraumatic splenic rupture is a rare but potentially life-threatening event. It mostly happens when the spleen is already diseased; however, sometimes it can be drug induced in a previously normal spleen. Although anticoagulation has been attributed to spontaneous splenic rupture quite frequently, the role of dual antiplatelet therapy is underestimated. We report a case of an 80-year-old woman who developed spontaneous splenic rupture 4 weeks after starting dual antiplatelet therapy

Mesodermal Dysmorphogenesis of Ginsenosides: An Experimental Study

Background: The versatile and dynamic activities of Panax Ginseng are attributed to its active components. They are readily available over the counter and are known for their effects as an aphrodisiac & health building; in addition, they are given rather generously during pregnancy, as they are considered virtuous for the baby and mother. Despite its easy availability and excess usage, little is known about its effects on the fetus. The current experimental design was focused towards the lack of differentiation and inhibition of cell growth of mesodermal derivatives inflicted by PanaxGingex. Methods:18 pregnant albino dams were randomly divided into three groups; Group A was control, Group B was Low dose and Group C was labeled as High dose groups. Tissues (bone, kidney and blood) were selected as derivatives of paraxial, intermediate and lateral plate mesoderm respectively and were used for light microscopic study. Results and Conclusion: The light microscopic examination demonstrated extensive apoptosis and an escalation of angiogenesis. Both the histological findings were not only statistically significant but was clearly indicative of dysmorphogenesis. The results of present study raise a finger towards the unsupervised practice of over the counter preparations especially during the vital antenatal period of development

TAGUCHI BASED OPTIMIZATION OF MACHINING PARAMETERS TO CONTROL SURFACE ROUGHNESS USING TiAlN-COATED TUNGSTEN CARBIDE MILLING CUTTER

Surface roughness is one of the determinant factors that governs the quality of machined surfaces. This paper experimentally studied effects of machining parameters on the surface roughness (Ra) for end milling of AISI 1045 work piece using a TiAlN coated carbide milling cutter. Taguchi optimization method was used to determine the optimal level of three control factors, namely, the feed rate, the spindle speed and the depth of cut. Analysis of variance demonstrates that the feed rate is the most significant parameter and contributes 47% for surface roughness. Finally, the contour plots of these three parameters have been analysed to determine the optimal ranges of control factors

COMBUSTION CHARACTERISTICS OF REACTIVE NANOMATERIALS

The combustion ofmetallic particlesis analogous to the combustion of hydrocarbon particles andthe particleburn time can be related to its diametric length. The relationship is called ‘d’ law and represented astb=d2. From the physics aspect, many deviations from the established laws at the bulk scale have been reported. As the ignition temperature of energetic nanomaterials is more sensitive to the passivation layer and the external heating conditions, and the burning time of nanomaterials is deviated from the conventional d2 law. Due to the variation of certain parameters such as the particles size distribution, agglomeration, morphology, level of contamination and initial particle size,thecorrect and precise value of the exponentisdifficult to find.Consequently, there’s no universal law for the burn time and a variant of the dn law is always proposed whose exponent is less than 2 (~ 1.3-1.7).In this research, combustion experiments are performed using a Bunsen burner in a particle-laden methane stream and the relationship of particle burning time with particle diameter is found to betb ~ d1.2. The combustion process of the various particles is captured using a high speed video camera.The average values of extinction time for Si (720 nm) and Si (1000 nm) are 11.4 ms and 17.2 ms, respectively. It is also observed that the nanoparticles are more reactive than the microsized particles. The average velocity flow fields of the silicon, iron and aluminum particles are also investigatedusing PIV technique.Before and after the experiments, the particles are characterised using dynamic light scattering (DLS), scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDS) and transmission electron microscopy (TEM

Survey and taxonomy of clustering algorithms in 5G

The large-scale deployment of fifth generation (5G) is expected to produce a massive amount of data with high variability due to ultra-densification and the rapid increase in a heterogeneous range of applications and services (e.g., virtual reality, augmented reality, and driver-less vehicles), and network devices (e.g., smart gadgets and sensors). Clustering organizes network topology by segregating nodes with similar interests or behaviors in a network into logical groups in order to achieve network-level and cluster-level enhancements, particularly cluster stability, load balancing, social awareness, fairness, and quality of service. Clustering has been investigated to support mobile user equipment (UE) in access networks, whereby UEs form clusters themselves and may connect to BSs. In this paper, we present a comprehensive survey of the research work of clustering schemes proposed for various scenarios in 5G networks and highlight various aspects of clustering schemes, including objectives, challenges, metrics, characteristics, performance measures. Furthermore, we present open issues of clustering in 5G

Flow boiling heat transfer characteristics of R600a and R290 in vertical mini-channels

High heat dissipation from compact modern electronic devices demands smart cooling solutions to ensure proper functionality. Two phase heat transfer has the capability to cope with high heating/cooling demands with better temperature uniformity along the chip. Refrigerant related environmental concerns (ozone depletion, global warming etc.) instigated recent surge for new alternatives. Natural refrigerants are regaining their fame, however reliable experimental studies under wide operating conditions are required for designing novel practical devices. Keeping in view the current demands, this study is focused on the thermal performance of two natural hydrocarbon refrigerants (Isobutane R600a, and Propane R290) in uniformly heated small vertical stainless steel tubes. The heat transfer performance of natural refrigerants is also compared with R134a under similar experimental conditions.  The experiments are carried out under wide operating conditions and continued till completion of dryout. The effects of operating parameters (heat flux, mass flux, vapor quality, saturation temperature etc.) along with assessment of macro and micro-scale correlations are the very subjects of this study