199 research outputs found
Unknown Author Letter : April 8, 1865
No full textThis is a letter from an unknown Union soldier to an unknown recipient. It is possible that the author is Dexter Denio. The writer mostly talks about his experiences with the rebels. They are well fed and talk of murder and thievery. When his company won a recent fight, they all had a large amount of the rebel's livestock to choose from for their dinners. The author also shows his strong loyalty and patriotism to the North's cause
Short-Range Ultra-Wideband Imaging with Multiple-Input Multiple-Output Arrays
No full textCompact, cost-efficient and high-resolution imaging sensors are especially desirable in the field of short-range observation and surveillance. Such sensors are of great value in fields of security, rescue and medical applications. Systems can be formed for various practical purposes, such as detecting concealed weapons in public places, locating people inside buildings or beneath rubbles during emergency rescue, detecting landmine with small vehicle-based systems, and finding early-stage lesions inside human bodies. The advantage of such systems is that imaging can be achieved in real-time, which allows for safer and more effective operation as well as intelligence gathering. In order to observe moving targets, the system must operate quickly enough to generate a focused real-time 3-D image. Cost efficiency is another factor to consider for market reasons. Existing systems based on synthetic aperture radar (SAR) technology or array with sequential operation of identical transceiver pairs are costly, thus commercially difficult to be widely deployed. Their drawbacks are obvious when compared with compact, lightweight and high-resolution imaging systems which can provide real-time perception of the target. The combination of ultra-wideband (UWB) technology and real-aperture multiple-input multiple-output (MIMO) array offers a novel and practical solution for safe, reliable and cost-efficient imaging sensors with high resolution capability. UWB impulse with high fractional bandwidth controls the appearance of grating lobes caused by the sparsity of the array; while asymmetric transmit and receive arrays further reduce the number of required antenna elements within the array aperture. Compared to the conventional SAR systems, the combined advantages of UWB technology and MIMO technique can drastically reduce element density, data-acquisition time and the system costs. The development of UWB-MIMO array and related imaging algorithms is an important and novel research subject. The International Research Centre for Telecommunications and Radar (IRCTR) of Delft University of Technology has initiated several projects with the purpose to develop high performance array-based UWB imaging systems for different short-range applications. Under this framework, my research has achieved the following novelties and main results which are elaborated in the thesis: Properties of UWB focusing. A novel theory of ultra-wideband focusing is proposed, which has corrected the previous misunderstanding of the impact of bandwidth on imaging. The proposed theory shows that sparsity only ensures the existence of a grating lobe free region within the image space rather than the complete absence of grating lobes. Instead, the bandwidth relative to the center frequency, or fractional bandwidth, has deterministic impact on the formation of grating lobes. Specifically, the bandwidth of an imaging system must exceed its central frequency in order to benefit from the merit of wideband impulse properties, allowing high-resolution imaging with significantly reduced number of antenna elements. The proposed theory helps to resolve the dilemma between angular resolution and grating lobe level for a sparse aperture/array. MIMO array topology design. Novel design approaches for one-dimensional and two-dimensional MIMO arrays have been proposed. They allow direct formation of array topologies without the need of numerical optimization. The designed arrays following the proposed strategies are able to provide three-dimensional imaging capabilities and low grating/side lobe level with large element spacing and minimum number of antenna elements. Combination of UWB technology and MIMO array technique. It is demonstrated that the combination of UWB and MIMO array is a beneficial concept for microwave imaging systems. The MIMO array-based UWB imaging system is able to provide high down- and cross-range resolution, low side/grating lobe level, simplified RF scheme and significantly increased data acquisition speed. A procedure for designing UWB-MIMO array for short-range imaging has been formulated. The process translates requirements from the application into specific array specifications, such as operational frequency band, number of elements needed, aperture dimension, and array topology. Modified Kirchhoff migration for MIMO configuration. Modified Kirchhoff migration has been developed for both free-space and subsurface imaging. The modifications allow for extension of the classical Kirchhoff algorithm, which is based on the exploding reflector concept and is formulated for co-located transmit-receive antennas, to multistatic imaging with arbitrary positions of transmit and receive antennas. The algorithm combines the high quality imaging performance with acceptable computational costs, thus can be applied to demanding applications in practice. Range migration algorithm for MIMO configuration. Range migration algorithm is formulated for multistatic array configuration in the frequency-wavenumber domain for near-field imaging. By taking advantage of the computation efficiency of the fast Fourier transform (FFT), imaging speed of MIMO array-based system are significantly increased while maintaining high-quality imaging capabilities. Demonstration of UWB-MIMO system in different applications. Within the framework of several European projects, prototypes of MIMO array-based UWB imaging systems were designed and implemented for through-wall imaging (PROBANT), ground penetrating radar (Cadmium), and concealed weapon detection (RADIOTECT, ATOM). The feasibility of operational systems under various practical circumstances has been demonstrated. Thanks to the combination of UWB focusing, MIMO array and advanced digital beamforming algorithms, high resolution 3-D images were obtained using sparse aperture array with simplified front-end and low-cost equipments.TelecommunicationsElectrical Engineering, Mathematics and Computer Scienc
Planar elliptically shaped dipole antenna for UWB Impulse Radio
No full textThe goal of this thesis was to develop design concepts of the UWB antenna with improved characteristics for impulse radio applications. To reach this goal a number of theoretical and experimental investigations were carried out. The major result of the thesis is a number of novel concepts for UWB antennas including: - The shielded elliptically-shaped dipole; - The active UWB antenna with an integrated pulse generator on chip; - The differential feeding of balanced UWB antennas via a shielded loop; - -Reduced size elliptically-shaped dipoles; - The study of the environmental impact on transmission of ultra-short pulses via a pair of UWB antennas. Each of these concepts include a number of results, which we overview below and discuss their novelty and importance.Electrical Engineering, Mathematics and Computer Scienc
Antennas for Improved Ground Penetrating Radar: Modeling Tools, Analysis and Design
No full textElectrical Engineering, Mathematics and Computer Scienc
Influence of viscosity ratio on the impact properties of PS/HDPE blends prepared by extrusion and injection molding
No full textBlends of PS/HDPE were prepared by ribbon extrusion and injection molding. Three different PS and HOPE were used in order to modify the viscosity ratio (p). The impact properties and morphological study of test specimens are presented. The results indicate a different effect of the viscosity ratio depending of the processing method on the morphology and impact resistance. In general, it was observed better impact resistance in samples prepared by ribbon extrusion than the samples prepared by injection molding
Influence of viscosity ratio on the impact properties of PS/HDPE blends prepared by extrusion and injection molding
No full textBlends of PS/HDPE were prepared by ribbon extrusion and injection molding. Three different PS and HOPE were used in order to modify the viscosity ratio (p). The impact properties and morphological study of test specimens are presented. The results indicate a different effect of the viscosity ratio depending of the processing method on the morphology and impact resistance. In general, it was observed better impact resistance in samples prepared by ribbon extrusion than the samples prepared by injection molding
DETERMINATION OF HEAVY METALS IN SOILS UNDER PERIWINKLE SHELL DUMPSITES LOCATED IN CHOBA AND NKPOLU MARKETS IN PORT HARCOURT, NIGERIA
No full textAbstract: Soil samples under periwinkle sediments were collected from Choba and Nkpolu markets in Port Harcourt. Analysis was carried out on them using AAS to detect the presence of heavy metals. The results showed that the concentrations of these metals ranged from 0.548-1.024mg/kg for chromium; 0.174-0.263mg/kg for zinc; 0.439-0.643mg/kg for copper; 1.535-1.676mg/kg for iron; 0.323-0.499mg/kg for cadmium; 0.561-0.864mg/kg for manganese; 0.255-0.0468mg/kg for nickel and 0.302-0.535mg/kg for cobalt. Heavy metals are not easily excreted from shells but tend to bio-accumulate over a long period of time, especially during the rainy season. Heavy metal concentration above the permissible limit is harmful to soil, plant growth and causes severe health problems to humans. The use of waste shells in road and house construction is the best approach to reducing the effect of heavy metal pollution by shells.
Keywords: Periwinkle Shells, AAS, Heavy Metals, Soil, Sediments, Pollution.
Title: DETERMINATION OF HEAVY METALS IN SOILS UNDER PERIWINKLE SHELL DUMPSITES LOCATED IN CHOBA AND NKPOLU MARKETS IN PORT HARCOURT, NIGERIA
Author: Oriji, O.G, John, Godson Nnamdi
International Journal of Recent Research in Life Sciences (IJRRLS)
ISSN 2349-7823
Vol. 10, Issue 2, April 2023 - June 2023
Page No: 10-13
Paper Publications
Website: www.paperpublications.org
Published Date: 13-April-2023
DOI: https://doi.org/10.5281/zenodo.7825127
Paper Download Link (Source)
https://www.paperpublications.org/upload/book/DETERMINATION%20OF%20HEAVY-13042023-3.pdfInternational Journal of Recent Research in Life Sciences (IJRRLS), ISSN 2349-7823, Paper Publications, Website: www.paperpublications.or
Assessing brain structure and function with diffusion-weighted MRI: Application to stroke
No full textHuman brain consists of grey and white matter. Grey matter largely forms theouter layer of the brain, and is responsible for decision making and functioningof the human body. Complementary, the white matter (WM) contains thecommunication pathways between the grey matter areas. Diffusion-weightedmagnetic resonance imaging (dMRI) is an imaging modality allowing to modelthe brain’s white matter structures by making the MRI acquisition sensitive todiffusion processes. When brain structure is altered due to pathology, it can beassessed and quantified by analysing dMRI data...Biomechatronics & Human-Machine Contro
Defalcation of European Union Budget in the Romanian Criminal Law
No full textOne of the goals for Romania, after the 1st January 2007, was to protect the financial interests of the European Union to fight against fraud, corruption and other illegal activities. In order to achieve this target, the legal framework has been completed by the Law no. 161/2003 which introduced the article no. 182 in the text of the Law no. 78/2000 regarding prevention, discovery and punishing the corruption acts. The author analyses this new article and he develops the two constitutive elements (actus reus, mens rea), the objective and subjective aspects of the analyzed crime, the ways, the legal punishments applicable to this crime.fraud, financial interests, spending, incomes, actus reus, mens rea, legal punishments.
FORTUNA, VIRTÙ Y GLORIA CONSIDERACIONES SOBRE LA MORAL REPUBLICANA DE MAQUIAVELO
No full textIn this paper some key concepts, such as fortune, virtù, and glory,are considered in order to seek clarification regarding the problemof the relation between morality and politics in Machiavelli. TheMachiavellian virtù certainly includes a good deal of energy andtalent, but does not completely lack moral components. From theconcept of fortune we can derive a number of criteria for politicalaction, which form a part of the Machiavellian virtù, which, thoughdistant from the Christian morals of his time, places him within arepublican conception of morality. Starting from an inquiry into the concept of glory, we discover how glory is a reward for virtù, but itis not awarded to every politician who is successful in his ventures,but only to those who are able to save their country by benign mean
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