Achievable and Crystallized Rate Regions of the Interference Channel with Interference as Noise

The interference channel achievable rate region is presented when the interference is treated as noise. The formulation starts with the 2-user channel, and then extends the results to the n-user case. The rate region is found to be the convex hull of the union of n power control rate regions, where each power control rate region is upperbounded by a (n-1)-dimensional hyper-surface characterized by having one of the transmitters transmitting at full power. The convex hull operation lends itself to a time-sharing operation depending on the convexity behavior of those hyper-surfaces. In order to know when to use time-sharing rather than power control, the paper studies the hyper-surfaces convexity behavior in details for the 2-user channel with specific results pertaining to the symmetric channel. It is observed that most of the achievable rate region can be covered by using simple On/Off binary power control in conjunction with time-sharing. The binary power control creates several corner points in the n-dimensional space. The crystallized rate region, named after its resulting crystal shape, is hence presented as the time-sharing convex hull imposed onto those corner points; thereby offering a viable new perspective of looking at the achievable rate region of the interference channel.Comment: 28 pages, 12 figures, to appear in IEEE Transactions of Wireless Communicatio

Development of cost-effective nano-bainitic steels

The aim of this work is the development of low-cost, fast transforming nano-bainitic steel alloys for the purposes of lightweighting and fuel efficiency in the transportation industry. Three alloying strategies were investigated under the scope of this work. A high C (0.54-0.8 wt.%), low Mn strategy (0.3 wt.% Mn), a high C (0.67-0.95 wt.%), high Al-strategy (3 and 5 wt.%), and a low carbon (0.23 and 0.3 wt.), high Al (0.7 to 3 wt.%) contents. All the alloying strategies dispensed with the expensive substitutional elements Co, Cr and Ni. Fast transformation times ranging from 650 s to 4600 s were obtained for all the investigated conditions. The highest mechanical strengths were obtained by the low Mn alloying strategy, with tensile strengths ranging from 1900 - 2140 MPa at elongation values of about 10 %. Increasing the Al content within the second strategy lowers the transformation times compared to the alloys of the first strategy with similar C contents. However, because of their high Al-content, alloys of the second strategy required more C additions to maintain sufficiently low martensite start temperatures (Ms). This increase in C led to an overall increase in the transformation times within this strategy. On the other hand, increasing Al to 3 wt.% led to a drop in the maximum tensile strength from 2140 to 2000 MPa, while the elongation values remained constant at about 10 %, similar to those of the low Mn strategy. Further increasing Al to 5 wt.% yielded brief incubation periods and shorter transformation times (1000 – 1800 s) despite the high C contents utilized (0.67 – 0.94 wt.%). However, this came at the cost of a deterioration of the strength-ductility balance, with strength values ranging from 1330 – 1845 MPa and ductility of about 5 %. Increasing the Al content within the third strategy from 0.7 to 2.8 wt.% (~ 0.3 wt.% C and ~ 2.9 wt.% Mn) lowers the transformation time from 3000 to 2000 s, respectively, at a cost of a reduction in tensile strength and elongation from 1330 to 1270 MPa and from 13.5 to 7.7%, respectively. Introducing δ-ferrite to the microstructure of the 3 wt.% Al alloy (~ 0.23 wt.% C and ~ 4.2 wt.% Mn) increased elongation% up to 16% and reduced the tensile strength to 1105 MPa. Continuously cooling of alloys of this group at a rate of 0.3 Ks-1 yielded almost fully martensitic structures, with bainite partly forming only in the alloys with higher Al. A cooling rate of 0.03 Ks-1 increased the tensile strength by about 100 MPa at similar elongation values, while lowering the cooling rate down to 0.003 Ks-1 yielded similar properties as isothermal treatment because most of the transformation is concluded near the starting temperature. For both the low and high C groups, the impact properties increased with the increase of Al to 2 – 3 wt.% followed by a drop as the Al was increased further. Conversely, the presence of δ-ferrite severely deteriorated the impact properties of the microstructures generated. Impact testing of select alloys from (-160 to 50 °C) revealed that changing the Al content has no significant effect on the impact transition temperature. Generating deformation induced ferrite (DIF) in the microstructure of the low carbon group alloys prior to the bainitic transformation had inconclusive effects on the final properties, improving the uniform elongation in some cases while deteriorating it in others. Finally, select alloys were subjected to bake hardening investigations to help expand a newly developed module in MatCalc software into the field of fine bainitic steels. Strain ageing experiments reveal high bake hardening strengths ranging from 130 – 240 MPa after brief ageing times of less than 20 min. The developed model was able to successfully predict the bake hardening behaviour of the alloys investigated.Ziel dieser Arbeit ist die Entwicklung kostengünstiger, schnell umwandelnder nano-bainitischer Stahllegierungen für die Zwecke des Leichtbaus und der Kraftstoffeffizienz in der Transportindustrie. Im Rahmen dieser Arbeit wurden drei Legierungsstrategien untersucht. Eine Strategie mit hohem C- (0,54-0,8 Gew.-%) und niedrigem Mn-Gehalt (0,3 Gew.-% Mn), eine Strategie mit hohem C- (0,67-0,95 Gew.-%) und hohem Al-Gehalt (3 und 5 Gew.-%) sowie eine Strategie mit niedrigem Kohlenstoff- (0,23 und 0,3 Gew.-%) und hohem Al-Gehalt (0,7 bis 3 Gew.-%). Bei allen Legierungsstrategien wurde auf die teuren Substitutionselemente Co, Cr und Ni verzichtet. Für alle untersuchten Bedingungen wurden schnelle Umwandlungszeiten zwischen 650 s und 4600 s erzielt. Die höchsten mechanischen Festigkeiten wurden mit der Legierungsstrategie mit niedrigem Mn-Gehalt erzielt, wobei die Zugfestigkeiten zwischen 1900 und 2140 MPa bei Dehnungswerten von etwa 10 % lagen. Die Erhöhung des Al-Gehalts bei der zweiten Strategie senkt die Umwandlungszeiten im Vergleich zu den Legierungen der ersten Strategie mit ähnlichen C-Gehalten. Aufgrund ihres hohen Al-Gehalts benötigten die Legierungen der zweiten Strategie jedoch mehr C-Zusätze, um ausreichend niedrige Martensit-Starttemperaturen (Ms) zu erhalten. Diese Erhöhung des C-Gehalts führte zu einer allgemeinen Verlängerung der Umwandlungszeiten bei dieser Strategie. Andererseits führte eine Erhöhung des Al-Gehalts auf 3 Gew.-% zu einem Rückgang der maximalen Zugfestigkeit von 2140 auf 2000 MPa, während die Dehnungswerte bei etwa 10 % konstant blieben, ähnlich wie bei der Strategie mit niedrigem Mn-Gehalt. Eine weitere Erhöhung des Al-Anteils auf 5 Gew.-% führte trotz der hohen C-Gehalte (0,67 - 0,94 Gew.-%) zu kurzen Inkubationszeiten und kürzeren Umwandlungszeiten (1000 - 1800 s). Dies ging jedoch auf Kosten einer Verschlechterung des Festigkeits-Duktilitäts-Gleichgewichts, mit Festigkeitswerten von 1330 - 1845 MPa und einer Duktilität von etwa 5 %. Die Erhöhung des Al-Gehalts innerhalb der dritten Strategie von 0,7 auf 2,8 Gew.-% (~ 0,3 Gew.-% C und ~ 2,9 Gew.-% Mn) verkürzt die Umwandlungszeit von 3000 auf 2000 s, allerdings auf Kosten einer Verringerung der Zugfestigkeit und der Dehnung von 1330 auf 1270 MPa bzw. von 13,5 auf 7,7 %. Die Einführung von δ-Ferrit in das Gefüge der 3-Gew.- %-Al-Legierung (~ 0,23 Gew.-% C und ~ 4,2 Gew.-% Mn) erhöhte die Dehnung um bis zu 16 % und reduzierte die Zugfestigkeit auf 1105 MPa. Die kontinuierliche Abkühlung von Legierungen dieser Gruppe mit einer Rate von 0,3 Ks-1 führte zu fast vollständig martensitischen Strukturen, wobei sich nur in den Legierungen mit höherem Al-Anteil teilweise Bainit bildete. Eine Abkühlungsrate von 0,03 Ks-1 erhöhte die Zugfestigkeit um etwa 100 MPa bei ähnlichen Dehnungswerten, während eine Verringerung der Abkühlungsrate auf 0,003 Ks-1 ähnliche Eigenschaften wie eine isotherme Behandlung ergab, da der größte Teil der Umwandlung in der Nähe der Anfangstemperatur abgeschlossen ist. Sowohl bei der Gruppe mit niedrigem als auch bei der Gruppe mit hohem C-Gehalt stiegen die Kerbschlagzähigkeitseigenschaften mit der Erhöhung des Al-Gehalts auf 2 bis 3 Gew.-% an, gefolgt von einem Rückgang bei weiterem Anstieg des Al-Gehalts. Umgekehrt verschlechterte das Vorhandensein von δ-Ferrit die Kerbschlagzähigkeit der erzeugten Gefüge erheblich. Kerbschlagbiegeversuche an ausgewählten Legierungen im Temperaturbereich von -160 bis 50 °C zeigten, dass eine Änderung des Al-Gehalts keine signifikante Auswirkung auf die Kerbschlagübergangstemperatur hat. Die Erzeugung von verformungsinduziertem Ferrit (DIF) im Gefüge der Legierungen mit niedrigem Kohlenstoffgehalt vor der bainitischen Umwandlung hatte keine schlüssigen Auswirkungen auf die endgültigen Eigenschaften, wobei sich die gleichmäßige Dehnung in einigen Fällen verbesserte, während sie sich in anderen Fällen verschlechterte. Schließlich wurden ausgewählte Legierungen einer Bake-Hardening-Untersuchung unterzogen, um ein neu entwickeltes Modul der MatCalc-Software auf den Bereich der feinbainitischen Stähle auszuweiten. Die Alterungsversuche zeigen hohe Bake Hardening Festigkeiten von 130 - 240 MPa nach kurzen Alterungszeiten von weniger als 20 min. Das entwickelte Modell war in der Lage, das Bake-Hardening-Verhalten der untersuchten Legierungen erfolgreich vorherzusagen

Effect of Computer Animation via Movies on Biology Academic Achievement Among Students of the Faculty of Educational Sciences and Arts/ UNRWA

This study investigated the effect of computer animation via movies on biology academic achievement among students the Faculty of Educational Sciences and Arts/ UNRWA (FESA). Moreover, it investigated its effects on achieving higher and lower levels of thinking in biology. The population of the study consisted of all the students of the faculty of UNRWA Educational Sciences and Arts/ (FESA) enrolled in the Class teacher major for the year 2017-2018, the sample consisted of all 70 students enrolled in the biology course for the same year. A 40 items test was prepared to assess students’ academic achievement in biology as a whole, and their achievement of higher and lower levels of thinking in biology. To ensure the validity of that scale, a group of experts in the field of education were requested to determine its content validity. In addition, the Koderrchardson-20 (K, R-20) measurement was utilized to assess its reliability. Furthermore, the study adopted a pre-test post-test control group quasi-experimental design. Finally, SPSS software was adopted to analyze the data adequately. The findings of the study showed that there are differences of statistical significance at (0.05) level. This revealed that students taught with animation have higher achievement in biology than those taught with conventional method. The findings imply that animation had a positive effect on students’ achievement in biology on general, and on achieving the higher and lower levels in thinking in biology. It is recommended to use the computer animation via movies extensively in teaching university courses. Keywords: Computer animation via movies; Achievement; Higher levels of thinking; Lower levels of thinking, Body Systems; FESA

Resource Allocation for Broadband Wireless Access Networks with Imperfect CSI

The high deployment and maintenance costs of last mile wireline networks (i.e., DSL and cable networks) have urged service providers to search for new cost-effective solutions to provide broadband connectivity. Broadband wireless access (BWA) networks, which offer a wide coverage area and high transmission rates in addition to their fast and low-cost deployment, have emerged as an alternative to last mile wireline networks. Therefore, BWA networks are expected to be deployed in areas with different terrain profiles (e.g., urban, suburban, rural) where wireless communication faces different channel impairments. This fact necessitates the adoption of various transmission technologies that combat the channel impairments of each profile. Implementation scenarios of BWA networks considered in this thesis are multicarrier-based direct transmission and single carrier-based cooperative transmission scenarios. The performance of these transmission technologies highly depends on how resources are allocated. In this thesis, we focus on the development of practical resource allocation schemes for the mentioned BWA networks implementation scenarios. In order to develop practical schemes, the imperfection of channel state information (CSI) and computational power limitations are among considered practical implementation issues. The design of efficient resource allocation schemes at the MAC layer heavily relies on the CSI reported from the PHY layer as a measure of the wireless channel condition. The channel estimation error and feedback delay renders the reported CSI erroneous. The inaccuracy in CSI propagates to higher layers, resulting in performance degradation. Although this effect is intuitive, a quantitative measure of this degradation is necessary for the design of practical resource allocation schemes. An approach to the evaluation of the ergodic mutual information that reflects this degradation is developed for single carrier, multicarrier, direct, and cooperative scenarios with inaccurate CSI. Given the CSI estimates and estimation error statistics, the presented evaluation of ergodic mutual information can be used in resource allocation and in assessing the severity of estimation error on performance degradation. A point-to-multipoint (PMP) network that employs orthogonal frequency division multiple access (OFDMA) is considered as one of the most common implementation scenarios of BWA networks. Replacing wireline networks requires not only providing the last mile connectivity to subscribers but also supporting their diverse services with stringent quality of service (QoS) requirements. Therefore, the resource allocation problem (i.e., subcarriers, rate and power allocation) is modeled as a network utility maximization (NUM) one that captures the characteristics of this implementation scenario. A dual decomposition-based resource allocation scheme that takes into consideration the diversity of service requirements and inaccuracy of the CSI estimation is developed. Numerical evaluations and simulations are conducted to validate our theoretical claims that the scheme maximizes resource utilization, coordinates with the call admission controller to guarantee QoS, and accounts for CSI inaccuracy. Cooperation has recently received great attention from the research community and industry because of its low cost and fast deployment in addition to the performance improvement it brings to BWA networks. In cooperative scenarios, subscribers cooperate to relay each other's signals. For this implementation scenario of BWA networks, a robust and constrained Kalman filter-based power allocation scheme is proposed to minimize power consumption and guarantee bit error probability (BEP) requirements. The proposed scheme is robust to CSI inaccuracy, responsive to changes in BEP requirements, and optimal in allocating resources. In summary, research results presented in this thesis contribute to the development of practical resource allocation schemes for BWA networks

Real-time system identification using deep learning for linear processes with application to unmanned aerial vehicles

This paper proposes a novel parametric identification approach for linear systems using Deep Learning (DL) and the Modified Relay Feedback Test (MRFT). The proposed methodology utilizes MRFT to reveal distinguishing frequencies about an unknown process; which are then passed to a trained DL model to identify the underlying process parameters. The presented approach guarantees stability and performance in the identification and control phases respectively, and requires few seconds of observation data to infer the dynamic system parameters. Quadrotor Unmanned Aerial Vehicle (UAV) attitude and altitude dynamics were used in simulation and experimentation to verify the presented methodology. Results show the effectiveness and real-time capabilities of the proposed approach, which outperforms the conventional Prediction Error Method in terms of accuracy, robustness to biases, computational efficiency and data requirements.Comment: 13 pages, 9 figures. Submitted to IEEE access. A supplementary video for the work presented in this paper can be accessed at: https://www.youtube.com/watch?v=dz3WTFU7W7c. This version includes minor style edits for appendix and reference

Metal concentrations in river water and bed sediments of the Lower Litani River Bassin, Lebanon

The distribution of pollutants in the Litani River is almost severe. It resulted from domestic, sewage, agricultural and industrial sources. In this study, the distribution of metals (Cu, Fe, Cd, Mg, Zn, Pb , Al, Ba, Ni, Mn, Ag and Cr) were measured in river water and the bed sediments of the Lower Litani River Basin (LLRB). The impacts of metals on the water quality were monitored during the rainy, mid rainy and dry season in the year 2012. The objectives of this study were first to identify possible sources of metals (i.e. geological and/or anthropogenic) and then to characterize the chemical behavior of these metals in water and bed sediments. Water and bed load sediments were sampled at six sites along the LLRB main watercourse, The metal concentrations in the river sediments were remarkably high, but varied between different sampling sites, and the concentrations in water were mainly within the permissible limits. The metal contents in bed sediment were highest during closure of summer period. By applying the principal component analysis applied to total and extractable metal contents as a tool for studying metal pollution in the LLRB, it was useful to distinguish between anthropogenic and natural sources

Physiochemical and Microbial Assessment of Water Quality in the Upper Litani River Basin, Lebanon

Water resources in Lebanon are witnessing serious challenges and reached depletion. One of the major challenges is the quality deterioration, which is accompanied with uncontrolled resources management, and thus the increasing demand. There are several consumption aspects, mainly the domestic, industrial and irrigation. Yet, exploitation of water resources in Lebanon implies both the surface and groundwater. However, surface water resources are most used due to the ease of exploitation processes, and more certainly water from rivers. Typically, the Litani River is the largest one in Lebanon. The river has been lately subjected to several aspects of deterioration in its quality. This includes the major physiochemical characteristics. This study aims to assess the seasonal variations in water quality in the Upper Litani River Basin, including the Qaraaoun Lake. Samples were collected from particular sites along the river, and at several dates during the years of 2010 and 2011. The carried analysis implies the physical (pH, T°, TDS, Ec), chemicals (Na+, Ca2+, Mg2+, Cl?, SO42?, NH3+, NO3?, PO42?, K+, BOD5 and COD, Heavy metals (Fe, Ni, Zn, Cu, Cr, Al, Ba, Pb, Mn) and microbiological parameters. This resulted numeric data are being compared with WHO guidelines. In addition, PCA was applied to evaluate the data accuracy. We can conclude that the variables used are very efficient and the dry season shows the worst water quality with nitrate, metal and microbial enrichments. Keywords: Water Contamination, Human Interference, Litani River, Principal Component Analysis