Pattern Nulling of Linear Antenna Arrays Using Backtracking Search Optimization Algorithm

An evolutionary method based on backtracking search optimization algorithm (BSA) is proposed for linear antenna array pattern synthesis with prescribed nulls at interference directions. Pattern nulling is obtained by controlling only the amplitude, position, and phase of the antenna array elements. BSA is an innovative metaheuristic technique based on an iterative process. Various numerical examples of linear array patterns with the prescribed single, multiple, and wide nulls are given to illustrate the performance and flexibility of BSA. The results obtained by BSA are compared with the results of the following seventeen algorithms: particle swarm optimization (PSO), genetic algorithm (GA), modified touring ant colony algorithm (MTACO), quadratic programming method (QPM), bacterial foraging algorithm (BFA), bees algorithm (BA), clonal selection algorithm (CLONALG), plant growth simulation algorithm (PGSA), tabu search algorithm (TSA), memetic algorithm (MA), nondominated sorting GA-2 (NSGA-2), multiobjective differential evolution (MODE), decomposition with differential evolution (MOEA/D-DE), comprehensive learning PSO (CLPSO), harmony search algorithm (HSA), seeker optimization algorithm (SOA), and mean variance mapping optimization (MVMO). The simulation results show that the linear antenna array synthesis using BSA provides low side-lobe levels and deep null levels

Effects of IAA, IBA, NAA, and GA3 on Rooting and Morphological Features of Melissa officinalis

This study analyzed the potential of producing Melissa officinalis L. using stem cuttings. Four different hormones (IAA, IBA, NAA, and GA3) were applied to the cuttings, with and without buds, in two doses (1000 mg/L and 5000 mg/L), and after 60 days, 10 morphological characteristics of newly generated plants were detected, and a statistical analysis was carried out. The results of the study show that the cuttings with at least one bud must be used in order to produce M. officinalis using stem cuttings. Even though the auxin group hormones (IAA, IBA, and NAA) do not have an apparent effect on rooting percentage, these hormones were detected to affect the morphological characteristics of the newly generated plants, especially root generation. GA3 application has a considerable effect on stem height

Effects of Some Hormone Applications on Germination and Morphological Characters of Endangered Plant Species Lilium artvinense L. Seeds

Lilies are economically important plants because of their large and attractive flowers. Thus, many wild species of lilies have been cultivated to produce Lilium bulbs or flowers. This work was conducted to analyse the effect of hormone applications on Lilium artvinense (Syn: Lilium ponticum K. Koch., Lilium ponticum var. artvinense (Miscz.) P. H. Davis and D. M. Hend., Lilium carniolicum var. artvinense (Miscz.) P. H. Davis and D. M. Hend and Lilium pyrenaicum var. artvinense (Miscz.) V.A. Matthews) seeds on germination percentage and seedlings morphological traits. In the research, 1000, 3000 and 5000 ppm doses of IAA, IBA, NAA and GA3 hormones were applied to L. artvinense seeds and approximately 180 days later, the number of roots, root length, offset stem height and diameter were assessed. As a result, while the control group except 5000 ppm NNA application achieved an increase in the percentage of germination (40%) of all the applications. Germination frequency up to 100% was obtained using 5000 ppm GA3. Effects of hormone applications on other key morphological characters (rooting percentage, root height, number of scions, scion height and width) are described in terms of growth rate between 1.27 and 2.44

Antenna Array Synthesis and Failure Correction Using Differential Search Algorithm

Differential search (DS) optimization algorithm is proposed for the synthesis of three different types of linear antenna array design examples. The first group of examples is that DS algorithm is used to locate wide nulls on the linear antenna array patterns by controlling amplitude-only. In these examples, sidelobe levels disposed to rise are also suppressed by using DS algorithm in the same optimization process. In the second group of examples, individual nulls are placed with the help of DS algorithm by controlling the amplitude-only, phase-only, and position-only. The last example is a linear antenna array failure correction example. In order to tolerate the element failures, DS is employed to recalculate the amplitude values of the remaining intact elements of the antenna array. The results show that DS is very capable to solve the linear antenna array optimization problems which have different characteristics

Utjecaj fitohormona na sposobnost zakorjenjivanja reznica vrste Ficus benjamina L.

Vegetative production techniques, of which cutting method widely used in propagation of ornamental plants, have a crucial role for conserving the plant genetic sources. On rooting development of stem cuttings, cutting position, rooting medium and rooting hormone are some of the critical factors that affect the success. The primary objective of this study is to determine the best hormone doses and ideal rooting medium on Ficus benjamina L. stem cuttings. Conventionally, the most frequently vegetative propagation method is the rooting of the stem cuttings in various media such as, pearlite, peat, sand, through exposure to high-concentration rooting hormones (IBA, IAA, NAA, etc.). But, this conventional technique requires wide areas in the rooting stage of mass production, prevents monitoring the course of rooting, and necessitates large amount of materials used as hormones and rooting media. In this study, a new method that may be preferable in mass production of plants was tested. 39 different treatments were carried out, and their results were evaluated. Sand, and perlite were used as solid rooting media. Stem cuttings were kept in low-concentration hormones permanently after cutting (liquid medium). In this way, their rooting capability were examined. Rooting trials were conducted before stem cuttings were taken to solid rooting media. As conclusions, the highest rooting ratio were obtained for 10 ppm of NAA (94.43%) and 100 ppm of IBA (93.9%) in liquid media. Moreover, the highest root length and the average root length were quite low in liquid media.Tehnike vegetativne proizvodnje od kojih se metoda reznica uvelike koristi u razmnožavanju ukrasnog bilja, imaju ključnu ulogu za očuvanje genetskih izvora biljaka. Mjesto uzimanja reznice na biljci, medij ukorjenjivanja i fitohormon ukorjenjivanja neki su od ključnih čimbenika koji utječu na uspjeh razvoja zakorjenjivanja reznica od stabljike. Primarni cilj ovog istraživanja bio je utvrditi najbolje koncentracije fitohormona i idealni medij zakorjenjivanja za reznice od stabljike vrste Ficus benjamina L. Konvencionalno, najčešća metoda vegetativnog razmnožavanja je zakorjenjivanja pupova u različitim supstratima kao što su perlit, treset, pijesak do izloženosti visoko koncentriranim hormonima zakorjenjivanja (IBA, IAA, NAA, itd.). Ali ta konvencionalna tehnika zahtijeva široka područja u fazi zakorjenjivanja masovne produkcije, sprječava nadzor tijeka zakorjenjivanja i traži visoku količinu materijala koji se koriste kao hormoni i mediji zakorjenjivanja. U ovom istraživanju, ispitana je nova metoda koja bi mogla biti poželjnijom u masovnoj proizvodnji biljaka. Izvršeno je 39 različitih tretiranja i prikazani su njihovi rezultati. Pijesak i perlit korišteni su kao kruti medij zakorjenjivanja. Pupovi su se trajno čuvali u hormonima niske koncentracije nakon rezanja (tekući medij). Na taj način je ispitana njihova sposobnost zakorjenjivanja. Ispitivanja zakorjenjivanja provedena su prije nego su pupovi odnijeti u kruti medij zakorjenjivanja. Kao zaključak, dobiveni su najviši omjeri zakorjenjivanja za 10 ppm NAA (94.43%) te 100 ppm IBA (93.9%) u tekućim medijima. Najveća duljina korijena i prosječna duljina korijena bile su prilično male u tekućim medijima

Interference suppression of linear antenna arrays by amplitude-only control using a bacterial foraging algorithm

This paper presents a bacterial foraging algorithm (BFA) for null steering of linear antenna arrays by controlling only the element amplitudes. The BFA is a new evolutionary computing technique based on the foraging behavior of Escherichia (E.) coli bacteria in human intestine. To show the accuracy and flexibility of the proposed BFA, several examples of Chebyshev array pattern with the imposed single, multiple and broad nulls are given. It is found that the nulling method based on BFA is capable of steering the array nulls precisely to the undesired interference directions

A quantized water cycle optimization algorithm for antenna array synthesis by using digital phase shifters

In this article, a quantized water cycle algorithm (QWCA) is used for the antenna array pattern synthesis with low side-lobe levels (SLLs) and nulls at desired directions by using four-bit digital phase shifters. In addition to the standard features as a metaheuristic algorithm, QWCA has an internal quantization mechanism and a precalculated array factor method. The latter provides an accelerated procedure to QWCA under favour of the digitized values that can be stored in a three-dimensional array. This acceleration is based on the reality that the accessing data in the memory need less time than the usage of the mathematical functions throughout the optimization process. The internal quantization mechanism of QWCA is utilized to achieve digital values matching to the discrete values of the phase shifter instead of the simple rounding up/down routines after optimization. The numerical results showed that QWCA can obtain very good SLLs and null depth levels (NDLs) on the synthesized pattern. Moreover, the results are achieved in remarkably short optimization times. SLL and NDL values obtained by QWCA are also compared with the available literature values. The comparisons reveal that QWCA is able to produce better results than the other compared alternatives

Computation of resonant frequency for equilateral triangular microstrip antennas using the adaptive neuro-fuzzy inference system

A,new method based on the adaptive neuro-fuzzy inference system (ANFIS) for calculating the resonant frequency of the equilateral triangular microstrip patch antenna is presented. The ANFIS has the advantages of the expert knowledge of the fuzzy inference system and the learning capability of neural networks. A hybrid-learning algorithm, which combines the least-square method and the backpropagation algorithm, is used to identify the parameters of ANFIS. The results of the new method show better agreement with the experimental results, as compared to the results of previous methods available in the literature. (C) 2004 Wiley Periodicals, Inc

A parallel implementation of seeker optimization algorithm for designing circular and concentric circular antenna arrays

In this paper, a parallel version of seeker optimization algorithm (SOA) is proposed for designing circular and concentric circular antenna arrays with the low sidelobe levels at a fixed beamwidth. The SOA is a relatively new evolutionary optimization algorithm based on the concept of simulating the act of humans’ intelligent search with their memory, experience, and uncertainty reasoning. In this work, The SOA has been parallelized by benefiting from its dividable population form. The numerical results show that the design of circular and concentric circular antenna arrays using the parallel SOA provides good sidelobe levels with a fixed beamwidth. The quality of results obtained by the parallel SOA is checked by comparing with those of several evolutionary algorithms in the literature

Comparison of adaptive-network-based fuzzy inference system models for resonant frequency computation of circular microstrip antennas

This paper presents a method based on adaptive-network-based fuzzy inference system (ANFIS) to compute the resonant frequency of a circular microstrip antenna (MSA). The ANFIS is a class of adaptive networks which are functionally equivalent to fuzzy inference systems (FISs). Seven optimization algorithms, least-squares, nelder-mead, differential evolution, genetic, hybrid learning, particle swarm, and simulated annealing, are used to determine optimally the design parameters of the ANFIS. The results of the ANFIS models show better agreement with the experimental results, as compared to the results of previous methods available in the literature. When the performances of ANFIS models are compared with each other, the best result is obtained from the ANFIS model trained by the least-squares algorithm