1,447 research outputs found

    A new operational matrix based on Bernoulli polynomials

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    In this research, the Bernoulli polynomials are introduced. The properties of these polynomials are employed to construct the operational matrices of integration together with the derivative and product. These properties are then utilized to transform the differential equation to a matrix equation which corresponds to a system of algebraic equations with unknown Bernoulli coefficients. This method can be used for many problems such as differential equations, integral equations and so on. Numerical examples show the method is computationally simple and also illustrate the efficiency and accuracy of the method

    Proportional-integral-plus control applications of state-dependent parameter models

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    This paper considers proportional-integral-plus (PIP) control of non-linear systems defined by state-dependent parameter models, with particular emphasis on three practical demonstrators: a microclimate test chamber, a 1/5th-scale laboratory representation of an intelligent excavator, and a full-scale (commercial) vibrolance system used for ground improvement on a construction site. In each case, the system is represented using a quasi-linear state-dependent parameter (SDP) model structure, in which the parameters are functionally dependent on other variables in the system. The approach yields novel SDP-PIP control algorithms with improved performance and robustness in comparison with conventional linear PIP control. In particular, the new approach better handles the large disturbances and other non-linearities typical in the application areas considered

    Optical Properties for SeTe Thin Films

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    Chalcogenide glasses SeTe have been prepared from the high purity constituent elements .Thin films of SeTe compound have been deposited by thermal evaporation onto glass substrates for different values of film thickness . The effect of varying thickness on the value of the optical gap is reported . The resultant films were in amorphous nature . The transmittance spectra was measured for that films in the wavelength range (400-1100) nm . The energy gap for such films was determined

    Cost-effective Information and Communication Technology (ICT) infrastructure for Tanziania

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    The research conducted an Information and Communication Technology (ICT) field survey, the results revealed that Tanzania is still lagging behind in the ICT sector due to the lack of an internationally connected terrestrial ICT infrastructure; Internet connectivity to the rest of the world is via expensive satellite links, thus leaving the majority of the population unable to access the Internet services due to its high cost. Therefore, an ICT backbone infrastructure is designed that exploits optical DWDM network technology, which un-locks bandwidth bottlenecks and provides higher capacity which will provide ICT services such as Internet, voice, videos and other multimedia interactions at an affordable cost to the majority of the people who live in the urban and rural areas of Tanzania. The research analyses and compares the performance, and system impairments, in a DWDM system at data transmission rates of 2.5 Gb/s and 10 Gb/s per wavelength channel. The simulation results show that a data transmission rate of 2.5 Gb/s can be successfully transmitted over a greater distance than 10 Gb/s with minimum system impairments. Also operating at the lower data rate delivers a good system performance for the required ICT services. A forty-channel DWDM system will provide a bandwidth of 100 Gb/s. A cost analysis demonstrates the economic worth of incorporating existing optical fibre installations into an optical DWDM network for the creation of an affordable ICT backbone infrastructure; this approach is compared with building a completely new optical fibre DWDM network or a SONET/SDH network. The results show that the ICT backbone infrastructure built with existing SSMF DWDM network technology is a good investment, in terms of profitability, even if the Internet charges are reduced to half current rates. The case for building a completely new optical fibre DWDM network or a SONET/SDH network is difficult to justify using current financial data

    Towards the Next Generation of Location-Aware Communications

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    This thesis is motivated by the expected implementation of the next generation mobile networks (5G) from 2020, which is being designed with a radical paradigm shift towards millimeter-wave technology (mmWave). Operating in 30--300 GHz frequency band (1--10 mm wavelengths), massive antenna arrays that provide a high angular resolution, while being packed on a small area will be used. Moreover, since the abundant mmWave spectrum is barely occupied, large bandwidth allocation is possible and will enable low-error time estimation. With this high spatiotemporal resolution, mmWave technology readily lends itself to extremely accurate localization that can be harnessed in the network design and optimization, as well as utilized in many modern applications. Localization in 5G is still in early stages, and very little is known about its performance and feasibility. In this thesis, we contribute to the understanding of 5G mmWave localization by focusing on challenges pertaining to this emerging technology. Towards that, we start by considering a conventional cellular system and propose a positioning method under outdoor LOS/NLOS conditions that, although approaches the Cram\'er-Rao lower bound (CRLB), provides accuracy in the order of meters. This shows that conventional systems have limited range of location-aware applications. Next, we focus on mmWave localization in three stages. Firstly, we tackle the initial access (IA) problem, whereby user equipment (UE) attempts to establish a link with a base station (BS). The challenge in this problem stems from the high directivity of mmWave. We investigate two beamforming schemes: directional and random. Subsequently, we address 3D localization beyond IA phase. Devices nowadays have higher computational capabilities and may perform localization in the downlink. However, beamforming on the UE side is sensitive to the device orientation. Thus, we study localization in both the uplink and downlink under multipath propagation and derive the position (PEB) and orientation error bounds (OEB). We also investigate the impact of the number of antennas and the number of beams on these bounds. Finally, the above components assume that the system is synchronized. However, synchronization in communication systems is not usually tight enough for localization. Therefore, we study two-way localization as a means to alleviate the synchronization requirement and investigate two protocols: distributed (DLP) and centralized (CLP). Our results show that random-phase beamforming is more appropriate IA approach in the studied scenarios. We also observe that the uplink and downlink are not equivalent, in that the error bounds scale differently with the number of antennas, and that uplink localization is sensitive to the UE orientation, while downlink is not. Furthermore, we find that NLOS paths generally boost localization. The investigation of the two-way protocols shows that CLP outperforms DLP by a significant margin. We also observe that mmWave localization is mainly limited by angular rather than temporal estimation. In conclusion, we show that mmWave systems are capable of localizing a UE with sub-meter position error, and sub-degree orientation error, which asserts that mmWave will play a central role in communication network optimization and unlock opportunities that were not available in the previous generation

    Resistance To Change Among First Line Managers In Multinational Organizations In Malaysia

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    Dramatic changes in organization structure and culture have become an essence that more and more individuals and organizations are recognizing the importance of the way that they can overcome the resistance to change

    Characterizing of some hydrochemical parameters of Tigris River, Iraq, with the aid of GIS

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    Nine stations along Tigris River in Iraq were selected to study the spatial and temporal changes of some selected parameters for the period 2009-2012. These parameters include discharge, Total Dissolved Solids,(TDS),NO3,BOD and COD. Water type is of bicarbonate along the northern stations (Feshkhabour, Mosul, Sharkat and Samarra) and transforms into sulfate in the remaining central and southern stations. GIS was used to characterize the temporal and spatial changes of these parameters along the selected River Tigris stations. Discharges values of all stations show significant temporal decreasing patterns and spatial decreasing patterns along these stations were also noticed. TDS values show noticeable temporal changes for the present stations, whereas sharp increasing changes downstream direction were observed. NO3, BOD and COD spatial and temporal changes show that their values show no indication on pollution and that their values for the high and low flow conditions are within the normal range values. Keywords, discharge, water type, GIS, spatial analyses, temporal change, Tigris River, Ira
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