Design and Implementation of Radio Frequency Power Feeding Networks for Antenna Array Applications: Simulation and Measurements of Multiport, Equal and Unequal, Fixed and Reconfigurable Radio Frequency Power Feeding Networks for Narrow and Ultra-Wideband Applications

Power dividers are vital components and widely used in radio technology, such as antenna arrays, power amplifiers, multiplexers and mixers. A good example is the well-known Wilkinson power divider with its distinctive feeding network characteristics. A comprehensive review indicated that limited research is carried out in the area of planar multiport and reconfigurable power dividers in terms of the power levels between output ports. The main objectives of this work were to develop a small size power divider, a planer multi-output ports power divider and a power divider with a reconfigurable power division ratio. These power dividers were designed to operate over either an ultra-wideband frequency (3.1-10.6 GHz) or WLAN bands (2.4 or 5.2 GHz). A novel multi-layered topology solved the complexity of interconnecting isolation resistors by introducing an additional layer below the ground layer. The prototype was fabricated and tested to validate the results. The measurements and simulation were in good agreement. Finally, a novel uniplanar power divider with reconfigurable output power level difference was developed. The configurability feature was achieved by tuning the quarter wave transformer using one varactor diode. The power divider was applied to improve a full duplex system cancellation performance at the receiver element caused by interference from in-site transmitting antennas. This study investigated fixed power dividers, multi-output power dividers and reconfigurable power dividers. The measurements validated by the simulation results and applications proved the designed power dividers could be used in practical applications.Higher Committee for Education Development (HCED), Ira

Enhancement of flexibility in multi-energy microgrids considering voltage and congestion improvement: Robust thermal comfort against reserve calls

In recent years, multi-energy microgrid (MEM) has gained increasing interest, which could use clean and efficient electro-thermal resources, multi-energy storages (MESs) and demand response potential to improve the flexibility of MEM. However, maximizing the flexibility potential of MEM and alongside managing the electrical parameters (EPs) is a challenging modeling problem. In this paper, a probabilistic nonlinear model is presented to maximize the flexibility with all the power grid constraints taking into account EPs constraints using power flow. To this end, voltage profile and congestion improvement, robust thermal comfort provision during reserve call and MESs utilization are the key properties of the proposed model. The outcome of suggested model ensures sustainability in the MEM performance, which is an essential feature in modern smart cities. The presented model is applied to a distribution network in the UK and results illustrate how equipment scheduling and demand response leads to observe the EPs limitation and maximizes MEM flexibility. The achieved results show a decrease in MEM revenue (decrease of 34% and 24% without and with reserve commitment, respectively) and in contrast, a significant increase in flexibility compared to non-compliance with EPs constraints

Performance of Different Tomato Genotypes in the Arid Tropics of Sudan during the Summer Season. I. Vegetative Growth

Selected, eleven tomato genotypes of diverse origin were grown in a glasshouse of the Humboldt University of Berlin, Germany during 2002 and under field conditions in Shambat, University of Khartoum, Sudan for two successive seasons (2002/2003, 2003/2004). High temperatures under field conditions resulted in poor stand and stunted growth of tomato plants. Highly significant differences were encountered among the different genotypes for leaf area, leaf area ratio, leaf weight ratio, stem fresh and dry weight and leaf fresh and dry weight. Based on results obtained from this study, the genotype ‘Summerset’ proved to be more tolerant under high temperature conditions in comparison to other investigated genotypes and may be useful for exploitation under arid tropical region of Sudan

Comparative Study on the Natural and Synthetic Hormones ofClarias gariepinus Broodstock

The study was carried out for six (6) weeks at the Department of Fisheries Teaching and Research farm, Modibbo Adama University, Yola, to compare the reproductive performance of Clarias gariepinus using synthetic (ovaprim) and natural (C. gariepinus pituitary extract) hormones . At the end of the feeding trial, the fecundity, percentage fertilization, hatchability, and survival rates of the hatchlings were estimated using standard procedure. The hatchlings were further raised for six weeks and the increase in weight was determined. The results showed that female broodstock injected with C. gariepinus pituitary extract (CgPE) had a higher fecundity (124,000) while the female injected with Ovaprim had 65,000 eggs. The weight of the testes significantly differed (p<0.05) across the treatments, the right lobe weighed 1.63g while the left lobe weighed 1.98g . Subsequently, a higher fertilization rate was recorded in CgPE (91.1%) while Ovaprim had 85.55% . However, Ovaprim had a higher percentage hatchability of 82.93% while CgPE had 82.73% . At the end of the six (6) weeks feeding period, the survival rate was higher in the fish treated with CgPE (82.31%) while the fish injected with Ovaprim had 79.68% . The research exposed the efficacy of using CgPE in the absence of synthetic hormone, CgPE is a preferred substitute that Hatchery managers can utilize for fingerlings production

Robust Controller Analysis and Design of Medical Haptic Control System

Haptic interfaces for medial simulation prove to be especially useful for training in minimally invasive procedures. In this research, a framework that consists of relevant representation of operator and environment dynamic of a tele-manipulated haptic system is implemented. The uncertainty model of the operator and environment models is considered as well to study the influence on the aspects of stability and performance. The framework of H∞ loop shaping robust controller design is applied, then the stability and performance analysis is investigated. Parametric robust control design method is used as well for comparison. The v-gap metric is considered to develop an accurate measurement of uncertainty. Based on the obtained value of the v-gap an efficient procedure of robust control design is applied. The obtained values of v- gap were 0.1112 for the master and 9.755*10-4 for the slave parts of the haptic system, which indicate improved robustness of stability and performance as compared with the obtained values from parametric robust controller design

Application of microbial biocementation to improve the physico-mechanical properties of cement mortar

AbstractCalcite is one of the most common and wide spread mineral on Earth constituting 4wt% of the Earth’s crust. It is naturally found in extensive sedimentary rock masses, as lime stone marble and calcareous sandstone in marine, fresh water and terrestrial environments. Calcium carbonate is one of the most well known mineral that bacteria deposit by the phenomenon called biocementation or microbiologically induced calcite precipitation (MICP). Such deposits have recently emerged as promising binders for protecting and consolidating various building materials. Microbially enhanced calcite precipitation on concrete or mortar has become an important area of research regarding construction materials. This study describes a method of strength and water absorption improvement of cement–sand mortar by the microbiologically induced calcium carbonate precipitation. A moderately alkalophilic aerobic Sporosarcina pasteurii was incorporated at different cell concentrations with the mixing water. The study showed that a 33% increase in 28days compressive strength of cement mortar was achieved with the addition of about one optical density (1OD) of bacterial cells with mixing water. The strength and water absorption improvement are due to the growth of calcite crystals within the pores of the cement–sand matrix as indicated from the microstructure obtained from scanning electron microscopy (SEM) examination

COMPARATIVE ULTRASONOGRAPHIC MEASUREMENT OF RENAL SIZE AND ITS CORRELATION WITH AGE, GENDER, AND BODY MASS INDEX IN NORMAL SUBJECTS IN SULAIMANI REGION

Background: The renal size of a population is a very useful diagnostic parameter in the practice of medicine. Since the renal size is affected by various factors, it is necessary to first determine the normal value. Objective:The aim of this study is to provide an estimation of renal size in normal subjects in Sulaimani Teaching Hospital, and to study its relation with age, gender, and body mass index (BMI) using ultrasonography. Therefore, this provides a standard data for our locality as we are deficient of them. Method:A cross sectional descriptive study was conducted in Sulaimani Teaching Hospital during the period of June 2013 to February 2014. 450 random volunteer person were included in the study aging between 18 - 96 years, without any known renal diseases.The total sample of the study were 450 person. 239 person (53%) were females, while 211 person (47%) were males. The mean of the right renal size in males was 76553.9947 mm3, while the mean of the left renal size was 94493.9mm3. In females, the mean of the right renal size was 68324.0292mm3, while the mean of the left renal size was 84150.43264mm3. Mean renal size for the right kidney was 72210.9842 mm3,While the mean renal size for the left kidney was 89031.0296 mm3. Results:There was a positive correlation between the size of the right and left kidney, with the left kidney size which is larger. There was also a positive correlation between renal size and age, as renal size increased with age till the 5th decade of life. While the male renal size was greater than the female renal size with the same age group, there was a positive correlation between renal size and body mass index (BMI)

Assessment of lime treatment of expansive clays with different mineralogy at low and high temperatures

YesThis paper examines the impacts of clay mineralogy on the effectiveness of lime stabilisation at different temperatures. A comprehensive experimental programme was conducted to track down the evolution of lime-clay reactions and their durations through monitoring the evolution of strength gain at predetermined times using the Unconfined Compressive Strength (UCS) test. The study examined clays with different mineralogy compositions comprising Na+ Bentonite and Ball (Kaolinite) clay. Four different clays were tested including 100% bentonite, 100% Ball clay and two clay mixtures with ratios of 1:1 and 1:3 by mass of bentonite to Ball clay. All clays were treated using a range of lime content up to 25% and cured for a period of time up to 672 h at two different temperatures of 20 and 40 °C. The results showed that the continuity of the fast phase (stage 1) of strength gain was dependent on the availability of lime in particular at the higher temperature. Whereas, for the same lime content, the duration of the fast phase and the kinetic of strength gain were significantly related to the clay mineralogy and curing temperature. Except for the initial strength gain at 0 h curing time, the lime-treated Ball clay specimens at 20 °C appeared to show no strength gain throughout the curing period that extended up to 672 h. However, when curing occurred at 40 °C, the no strength gain stage only lasted for 72 h after which a gradual increase in the strength was observed over the remaining curing period of time. The addition of Bentonite to Ball clay succeeded in kicking off the strength gain after a short period of curing time at both curing temperatures

The effects of lime content and environmental temperature on the mechanical and hydraulic properties of extremely high plastic clays

YesThis paper focuses on monitoring the evolution of lime-clay reactions using geotechnical parameters as a function of lime content and environmental temperature. Lime contents of 5, 7, 9, 11 and 13% by dry weight of expansive clay powder were added to prepare lime-clay specimens. The specimens were prepared at the same dry unit weight of 12.16 kN/m3 and moisture content of 40% except for tests aimed at the determination of dry unit weight as a function of mellowing period. Prepared specimens were mellowed or cured at two different ambient temperatures of 20 °C and 40 °C. Results attained from Unconfined Compressive Strength and permeability tests were employed to assess the impact of lime content on the mechanical and hydraulic properties of lime treated expansive clays. The results revealed that at the beginning, the rate of strength gain is remarkably fast for a particular period of time which is dependent on lime content. Furthermore, the strength gain on specimens cured at 40 °C is 8 times higher than that observed on specimens cured at 20 °C which highlights significant effect for the environmental temperature on accelerating the chemical reactions. Reduced dry unit weight due to increased resistance to compactability is observable with increasing lime content and higher environmental temperature. Accelerated pozzolanic reaction at higher environmental temperature resulted in permeability coefficient of specimens mellowed for 24 h at 40 °C to be higher than those mellowed at 20 °C. The results also highlighted that the permeability coefficient would be relatively stable when expansive clays were treated with small amounts of lime e.g. 5%