Tefaruk HAKTANIR

Makale/Derleme | 2022 | Hydrological Sciences Journal67 ( 5 ) , pp.741 - 758

A new multiseries stochastic model is developed that takes n-year-long monthly stream flows observed at as many as 20 stations in a group and computes N-year-long synthetic monthly flows for up to 10 000 years. Initially, any series that exhibit trends with a 99% confidence level are detrended. The monthly flows of each observed series are transformed to standard-normal variates, and a variate is related to those of the other series of the same month, those of the previous month of all series, the lag-one moving-average component, and the random component. 2 M parameters of each series are iteratively computed by the least squares m . . .ethod, such that the variance of the random component determined using the observed variates and those computed by the model equals the variance given by the model. The model was applied to five groups in Anatolia. The relevant peculiarities of the observed and synthetic flows were in harmony Daha fazlası Daha az

Erkan KÖSE

Makale/Derleme | 2022 | Sadhana Indian Academy of Sciences 47 ( 3 ) , pp.1 - 10

The pharmaceutical supply chain consists of supplier, distributor (pharmaceutical warehouses) and retail (pharmacists) stages. Since the costs of some pharmaceuticals are high while their shelf life is short, it is not possible for pharmacies to keep all kinds of drugs in their stocks. Instead, pharmacies maintain reasonable amounts of inventory for products with high demand, while fulfilling orders for those with low demand through pharmaceutical warehouses. In this study, the real life drug distribution problem of a pharmacy warehouse that meets demands of 186 pharmacies in 9 regions is addressed. Optimal distribution routes that . . .minimize both the transportation time and the costs are obtained by using our two-stage optimization approach without changing the company’s infrastructure. At first, the multiple traveling salesman method, which is an extension of the traveling salesman problem, is used to determine the optimal routes. In the second stage, the system is simulated to determine the most suitable travel frequencies and the savings in the number of vehicles used. The results show that, savings of 52% in vehicles used and 46% in distance traveled per day can be obtained if the developed model is applied Daha fazlası Daha az

Mehmet BİLİM

Makale/Derleme | 2022 | TURKISH JOURNAL OF ELECTRICAL ENGINEERING AND COMPUTER SCIENCES30 ( 6 ) , pp.2031 - 2043

In this paper, we present error probability analysis for single-input single-output (SISO) and asymmetric dual-branch networks with additive white generalized Gaussian noise (AWGGN) over millimeter-wave (mmW) fluctuating two-ray (FTR) fading channels. Then, we examine the error probability evaluation of a SISO system with imperfect phase errors over mmW FTR fading channels. The probability density function (PDF) approach is employed for the error probability performance evaluation and the novel PDF of the asymmetric dual-branch system over Nakagami-m/mmW FTR fading channels is obtained. Specifically, closed-form expressions are deri . . .ved for the error probability of the SISO and asymmetric dual-branch networks. The derived error expressions facilitate in effectively evaluating the performance of considered networks in the presence of AWGGN and imperfect phase noise with optimal fading parameters and modulation type. The theoretical derivations are extensively confirmed through exact simulations Daha fazlası Daha az

Mehmet BİLİM

Makale/Derleme | 2022 | INTERNATIONAL JOURNAL OF COMMUNICATION SYSTEMS35 ( 13 ) , pp.1 - 15

This study presents the average symbol error probability (ASEP) performanceof a single-input single-output communication with imperfect phase error(IPE) and without IPE over the Beaulieu-Xie fading channels. The Beaulieu-Xie fading model is proposed recently and it is a popular characterization forthe line-of-sight and non-line-of-sight environments. The proposed theoreticalanalysis, which is based on the probability density function, is enough generaland applicable in some real-life scenarios. For both cases, closed-form exact,approximate, and asymptotic expressions are derived for the ASEP of differentmodulation types. Finally, ex . . .act simulations have been introduced to confirmthe accuracy of the theoretical findings obtained and present insights into theconsidered scheme performance Daha fazlası Daha az

Mehmet BİLİM

Makale/Derleme | 2022 | Physical Communication52 ( 2 ) , pp.1 - 6

In this study, the cascaded double κ−μ shadowed fading model is mathematically introduced. A novel expression is obtained for the cumulative distribution function (CDF) of the cascaded double κ−μ shadowed fading channels by using Meijer’s G function and Laplace transform. Based on the obtained CDF expression, the exact and asymptotic expressions are derived for the outage probability (OP), the average bit error rate (BER) for various modulations of the considered channel model. The OP and the average BER curves with exact simulations obtained by the proposed expressions are presented for different parameters and modulation schemes o . . .f the considered channel model. Finally, the accuracy of the derived OP and the average BER expressions is confirmed with exact simulations Daha fazlası Daha az

Erhan KURT | Kerim GÜNEY

Makale/Derleme | 2022 | Journal of Electrical Engineering-Elektrotechnicky Casopis73 ( 5 ) , pp.325 - 331

In this study, a modified version of salp swarm algorithm (MSSA) is used to synthesize elliptical antenna arrays (EAAs).The original salp swarm algorithm (SSA) is an optimization algorithm inspired by the behavior of salps in nature, which isused to solve engineering problems. The main purpose of the synthesis in this study is to obtain an EAA pattern with lowmaximum sidelobe levels (MSLs) for a fixed narrow first null beamwidth (FNBW). For different examples, the amplitude andangular position values of the antenna array elements are considered as optimization parameters. To show the effectivenessof the MSSA, eight examples of EAAs . . .with 8, 12, and 20 elementsare given. The results obtained with MSSA are comparedwith those of the antlion optimization, symbiotic organizations search, flower pollination algorithm, and accelerated particleswarm optimization from the literature. It is clear from thenumerical results that MSSA outperforms the other algorithmsin terms of the suppression of MSL Daha fazlası Daha az

Kerim GÜNEY | Erhan KURT

Makale/Derleme | 2022 | International Journal of Numerical Modelling: Electronic Networks, Devices and Fields , pp.1 - 18

Antenna array synthesis is quite a popular topic in electromagnetics and finding suitable array parameter values is a challenging nonlinear engineering problem in this field. In recent years, it has been realized that optimization algorithms can be used to achieve desired solutions in this area. Besides, improvements in the optimization algorithms make it possible to perform synthesis processes on different array structures and to obtain better results. In this paper, a method based on a combination of ant lion optimizer (ALO) and sequential quadratic programming (SQP) is proposed for the concentric circular antenna array (CCAA) syn . . .thesis. Excitation amplitudes of array elements are optimized for CCAAs with low maximum sidelobe level (MSL), narrow first null beamwidth (FNBW), and low dynamic range ratio (DRR). The results of proposed ALO-SQP method are compared with those of 11 different algorithms: ALO, moth flame optimizer (MFO), SQP, symbiotic organisms search (SOS), biogeography based optimization (BBO), opposition-based gravitational search algorithm (OGSA), cat swarm optimization (CSO), firefly algorithm (FA), evolutionary programming (EP), backtracking search optimization algorithm (BSA), and seeker optimization algorithm (SOA). The comparisons indicate that the CCAAs synthesis using the proposed method presents good MSLs, FNBWs, and DRRs Daha fazlası Daha az