2,630 research outputs found

    Rituals, Our Past, Present & Future. Glimpses of Islamic Enrichment

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    A Muslim should be encouraged to comprehend the benefit and value behind every aspect of Islamic practice and wisdom, and not just practice their religion because they were told to do so. The products proposed in this thesis aim to achieve this by inviting and encouraging a Muslim to practice The Five Pillars of Islam while comprehending their value through the use of modern means such as Arduino technology, 3D printing and visual computing programing. I am provoked by the fact that the circle of Gulf-region Muslims I’m surrounded by, and have been exposed to since childhood, belong to one of two stereotypes: those against or afraid of change who force adherence to religious chapter and verse, or those straying further and further away from our religion’s rituals and traditions. Can the practice of religion, and the values that it teaches us, be made more accessible and engaging by incorporating the very technology that is often accused of distracting us from its practice

    Class-Based Weighted Window for TCP Fairness in WLANs

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    The explosive growth of the Internet has extended to the wireless domain. The number of Internet users and mobile devices with wireless Internet access is continuously increasing. However, the network resource is essentially limited, and fair service is a key issue in bandwidth allocation. In this research, the focus is on the issue of fairness among wireless stations having different number and direction of flows for different required bandwidth to ensure that fair channel is fairly shared between wireless stations in the same class of bandwidth. It is shown that the current WLANs allocate bandwidth unfairly. It is also identified that the cause of this problem of unfairness is the TCP cumulative ACK mechanism combined with the packet dropping mechanism of AP queue and the irregular space for each wireless station in AP queue. The proposed method allocate converged bandwidth by introducing a Class-Based Weighted Window method which adjusts the TCP window size based on the current conditions of the network and according to the network’s requirements. This method works in wireless stations without requiring any modification in MAC. It can guarantee fair service in terms of throughput among wireless users whether they require the same or different bandwidth.Wireless LAN, TCP, Fairness

    Theory of Coupled Resonator Optical Waveguides (CROW) Exhibiting High Order Exceptional Points of Degeneracy

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    We present a novel approach and a theoretical framework for generating high order exceptional points of degeneracy (EPD) in photonic structures based on periodic coupled resonators optical waveguides (CROWs). Such EPDs involve the coalescence of Floquet-Bloch eigenwaves in CROWs, without the presence of gain and loss, which is in contrast to the requirement of Parity-Time (PT) symmetry to develop exceptional points based on gain and loss balance. The EPDs arise here by introducing symmetry breaking in a conventional chain of coupled resonators through coupling the chain of resonators to an adjacent uniform optical waveguide, which leads to unique modal characteristics that cannot be realized in conventional CROWs. Such remarkable characteristics include high quality factors (Q-factor) and strong field enhancement, even without any mirrors at the two ends of a cavity. We show for the first time the capability of CROWs to exhibit EPDs of various order; including the degenerate band edge (DBE) and the stationary inflection point (SIP). The proposed CROW of finite length shows enhanced quality factor when operating near the DBE, and the Q-factor exhibits an anomalous scaling with the CROW's length. We develop the theory of EPDs in such unconventional CROW using coupled-wave equations, and we derive an analytical expression for the dispersion relation. The proposed unconventional CROW concepts have various potential applications including Q-switching, nonlinear devices, lasers, and extremely sensitive sensors.Comment: 16 pages, 11 figure

    Groundwater Quality and Soil Characterization: A Case Study at Bukit Tembaga, Kuala Nerang, Kedah

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    Soil test can be used toanalyze soil characterization. The character of soils can reflect the quality of underground water. Nowadays groundwater can be used as an alternative to drinking water. The mineral contain in soil will give an added value to the quality of groundwater. This study extracted groundwater from lot 1981, Bukit Tembaga, Kuala Nerang Kedah which was in Padang Terap district. Generally this area is classified as hilly area and surrounded by a rubber plantation. The objective of this paper is to analyze characterization of the soil in term of oxide compound, groundwater quality and correlation between chemical concentration and groundwater quality. Chemical concentration in soil was analyzed using XRF. Groundwater quality was tested by using APHA standard 2012. The parameters for groundwater sourcewere compared with the Groundwater Standard. The correlation coefficientvalue is calculated using Pearson’s method. The results indicated that certain metals present in the soil and groundwater samples. The negative value of correlation coefficientproved that high concentration of metals in soil resulted to low concentration of metals in groundwater

    Optimizing Service Differentiation Scheme with Sized-based Queue Management in DiffServ Networks

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    In this paper we introduced Modified Sized-based Queue Management as a dropping scheme that aims to fairly prioritize and allocate more service to VoIP traffic over bulk data like FTP as the former one usually has small packet size with less impact to the network congestion. In the same time, we want to guarantee that this prioritization is fair enough for both traffic types. On the other hand we study the total link delay over the congestive link with the attempt to alleviate this congestion as much as possible at the by function of early congestion notification. Our M-SQM scheme has been evaluated with NS2 experiments to measure the packets received from both and total link-delay for different traffic. The performance evaluation results of M-SQM have been validated and graphically compared with the performance of other three legacy AQMs (RED, RIO, and PI). It is depicted that our M-SQM outperformed these AQMs in providing QoS level of service differentiation.Comment: 10 pages, 9 figures, 1 table, Submitted to Journal of Telecommunication

    Agile-SD: A Linux-based TCP Congestion Control Algorithm for Supporting High-speed and Short-distance Networks

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    Recently, high-speed and short-distance networks are widely deployed and their necessity is rapidly increasing everyday. This type of networks is used in several network applications; such as Local Area Networks (LAN) and Data Center Networks (DCN). In LANs and DCNs, high-speed and short-distance networks are commonly deployed to connect between computing and storage elements in order to provide rapid services. Indeed, the overall performance of such networks is significantly influenced by the Congestion Control Algorithm (CCA) which suffers from the problem of bandwidth under-utilization, especially if the applied buffer regime is very small. In this paper, a novel loss-based CCA tailored for high-speed and Short-Distance (SD) networks, namely Agile-SD, has been proposed. The main contribution of the proposed CCA is to implement the mechanism of agility factor. Further, intensive simulation experiments have been carried out to evaluate the performance of Agile-SD compared to Compound and Cubic which are the default CCAs of the most commonly used operating systems. The results of the simulation experiments show that the proposed CCA outperforms the compared CCAs in terms of average throughput, loss ratio and fairness, especially when a small buffer is applied. Moreover, Agile-SD shows lower sensitivity to the buffer size change and packet error rate variation which increases its efficiency.Comment: 12 Page

    Theory and New Amplification Regime in Periodic Multi Modal Slow Wave Structures with Degeneracy Interacting with an Electron Beam

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    We present the theory of a new amplification regime in Travelling Wave Tubes (TWTs) composed of a slow-wave periodic structure that supports multiple electromagnetic modes that can all be synchronized with the electron beam. The interaction between the multimodal slow-wave structure and the electron beam is quantified using a Multi Transmission Line approach (MTL) based on a generalized Pierce model and transfer matrix analysis leading to the identification of modes with complex Bloch wavenumber. In particular, we address a new possible operation condition for TWTs based on the super synchronism between an electron beam and four modes exhibiting a degeneracy condition near a band edge of the periodic slowwave MTL. We show a phenomenological change in the band structure of periodic MTL where we observe at least two growing modal cooperating solutions as opposed to a uniform MTL interacting with an electron beam where there is rigorously only one growing modal solution. We discuss the advantage of using such a degeneracy condition in TWTs that leads to larger gain conditions in amplifier regimes and also to very lowstarting beam current in high power oscillators.Comment: Version 2. 33 pages, 16 figure

    Achieving sustainable construction in the developing countries Of Southeast Asia

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    Sustainable construction is a way for the building industry to move towards achieving sustainable development, taking into account environmental, socioeconomic and cultural issues. Differing approaches and differing economic markets lead to different priorities. This paper presents the construction scenario of Southeast Asia and the developments in sustainable construction taking place in the region. Barriers to the implementation of sustainable construction are discussed. A list of recommendations was proposed to drive sustainable construction in the region. In conclusion, the status of sustainable construction in Southeast Asia is still in its infancy. The lack of awareness, training and education and ineffective procurement systems are among the major barriers for sustainable construction in the region. In some countries public policies and regulatory frameworks do not encourage the development of the construction sector. Besides the needs for capacities, technologies and tools, total and ardent commitment by all players in the construction sectors including the governments and the public at large are required in order to achieve sustainable construction in South-East Asia

    Graphene-Dielectric Composite Metamaterials: Evolution from Elliptic to Hyperbolic Wavevector Dispersion and The Transverse Epsilon-Near-Zero Condition

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    We investigated a multilayer graphene-dielectric composite material, comprising graphene sheets separated by subwavelength-thick dielectric spacer, and found it to exhibit hyperbolic isofrequency wavevector dispersion at far- and mid-infrared frequencies allowing propagation of waves that would be otherwise evanescent in a dielectric. Electrostatic biasing was considered for tunable and controllable transition from hyperbolic to elliptic dispersion. We explored the validity and limitation of the effective medium approximation (EMA) for modeling wave propagation and cutoff of the propagating spatial spectrum due to the Brillouin zone edge. We found that EMA is capable of predicting the transition of the isofrequency dispersion diagram under certain conditions. The graphene-based composite material allows propagation of backward waves under the hyperbolic dispersion regime and of forward waves under the elliptic regime. Transition from hyperbolic to elliptic dispersion regimes is governed by the transverse epsilon-near-zero (TENZ) condition, which implies a flatter and wider propagating spectrum with higher attenuation, when compared to the hyperbolic regime. We also investigate the tunable transparency of the multilayer at that condition in contrast to other materials exhibiting ENZ phenomena.Comment: to be published in Journal of Nanophotonic

    Performance evaluation of parallel TCP, and its impact on bandwidth utilization and fairness in high-BDP networks based on test-bed

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    After the presence of high Bandwidth-Delay Product (high-BDP) networks, many researches have been conducted to prove either the existing TCP variants can achieve an excellent performance without wasting the bandwidth of these networks or not. In this paper, a comparative test-bed experiment on a set of high speed TCP variants has been conducted to show their differences in bandwidth utilization, loss ratio and TCP-Fairness. The involved TCP Variants in this experiment are: NewReno, STCP, HS-TCP, H-TCP and CUBIC. These TCP variants have been examined in both cases of single and parallel schemes. The core of this work is how to evaluate these TCP variants over a single bottleneck network using a new parallel scheme to fully utilize the bandwidth of this network, and to show the impact of accelerating these variants on bandwidth utilization, loss-ratio and fairness. The results of this work reveal that, first: the proposed parallel scheme strongly outperforms the single based TCP in terms of bandwidth utilization and fairness. Second: CUBIC achieved better performance than NewReno, STCP, H-TCP and HS-TCP in both cases of single and parallel schemes. Briefly, parallel TCP scheme increases the utilization of network resources, and it is relatively good in fairness
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