Analysis of trusses by total potential optimization method coupled with harmony search

Toklu, Yusuf Cengiz,Bekdas, Gebrail,Temur, Rasim Techno-Press 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.45 No.2

Current methods of analysis of trusses depend on matrix formulations based on equilibrium equations which are in fact derived from energy principles, and compatibility conditions. Recently it has been shown that the minimum energy principle, by itself, in its pure and unmodified form, can well be exploited to analyze structures when coupled with an optimization algorithm, specifically with a meta-heuristic algorithm. The resulting technique that can be called Total Potential Optimization using Meta-heuristic Algorithms (TPO/MA) has already been applied to analyses of linear and nonlinear plane trusses successfully as coupled with simulated annealing and local search algorithms. In this study the technique is applied to both 2-dimensional and 3-dimensional trusses emphasizing robustness, reliability and accuracy. The trials have shown that the technique is robust in two senses: all runs result in answers, and all answers are acceptable as to the reliability and accuracy within the prescribed limits. It has also been shown that Harmony Search presents itself as an appropriate algorithm for the purpose.

Free-floating Vitreous Cyst in an Adult Male

Yasin Toklu,Sabri Raza,Hasan Basri Cakmak,Nurullah Cagil 대한안과학회 2013 Korean Journal of Ophthalmology Vol.27 No.6

A 50 year-old male patient was referred to our clinic due to a floating mass in the right eye. The uncorrectedvisual aquity was 10 / 10 in both eyes.The patient did not have any systemic disorder and trauma history. Hisophthalmological examination revealed an unremarkable anterior segment with no signs of inflammation. Indirect opthalmoscopy and posterior segment biomicroscopy performed with 90D lens was unremarkablein the left eye, while in the right eye a single oval cyst was identified floating freely in the vitreous. The cystwas partially masking the underlying retinal vasculature. B-scan ultrasound revealed an echo-free, roundshapedcyst that was free from surrounding vitreous strands or retina localised at the posterior vitreous. Fluorescein angiography (FA) ruled out the presence of intra and overlying vascularisation of the cyst. Indeed,FA showed a clear-edged hypofluorescence due to a pre-retinal masking effect. The indirect hemaglutinintests of the patient for ecinococcus and cysticercosis were negative. Eosinophilia was not detected in thepreripheral blood smear. Based on these findings the patient was diagnosed as primary vitreal cyst. Thepresented case was mild symptomatic so the patient was decided to be followed up without any treatment.

Analysis of trusses by total potential optimization method coupled with harmony search

Yusuf Cengiz Toklu,Gebrail Bekdaşa,Rasim Temur 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.45 No.2

Current methods of analysis of trusses depend on matrix formulations based on equilibrium equations which are in fact derived from energy principles, and compatibility conditions. Recently it has been shown that the minimum energy principle, by itself, in its pure and unmodified form, can well be exploited to analyze structures when coupled with an optimization algorithm, specifically with a meta-heuristic algorithm. The resulting technique that can be called Total Potential Optimization using Meta-heuristic Algorithms (TPO/MA) has already been applied to analyses of linear and nonlinear plane trusses successfully as coupled with simulated annealing and local search algorithms. In this study the technique is applied to both 2-dimensional and 3-dimensional trusses emphasizing robustness, reliability and accuracy. The trials have shown that the technique is robust in two senses: all runs result in answers, and all answers are acceptable as to the reliability and accuracy within the prescribed limits. It has also been shown that Harmony Search presents itself as an appropriate algorithm for the purpose.

Analysis of cable structures through energy minimization

Yusuf Cengiz Toklu,Gebrail Bekdaş,Rasim Temür 국제구조공학회 2017 Structural Engineering and Mechanics, An Int'l Jou Vol.62 No.6

In structural mechanics, traditional analyses methods usually employ matrix operations for obtaining displacement and internal forces of the structure under the external effects, such as distributed loads, earthquake or wind excitations, and temperature changing inter alia. These matrices are derived from the well-known principle of mechanics called minimum potential energy. According to this principle, a system can be in the equilibrium state only in case when the total potential energy of system is minimum. A close examination of the expression of the well-known equilibrium condition for linear problems, P=KΔ, where P is the load vector, K is the stiffness matrix and Δ is the displacement vector, it is seen that, basically this principle searches the displacement set (or deformed shape) for a system that minimizes the total potential energy of it. Instead of using mathematical operations used in the conventional methods, with a different formulation, meta-heuristic algorithms can also be used for solving this minimization problem by defining total potential energy as objective function and displacements as design variables. Based on this idea the technique called Total Potential Optimization using Meta-heuristic Algorithms (TPO/MA) is proposed. The method has been successfully applied for linear and non-linear analyses of trusses and truss-like structures, and the results have shown that the approach is much more successful than conventional methods, especially for analyses of non-linear systems. In this study, the application of TPO/MA, with Harmony Search as the selected meta-heuristic algorithm, to cables net system is presented. The results have shown that the method is robust, powerful and accurate.

Application of Big Bang - Big Crunch Optimization to Resource Constrained Scheduling Problems

Y. Cengiz Toklu 대한토목학회 2018 KSCE JOURNAL OF CIVIL ENGINEERING Vol.22 No.12

Last decades have witnessed emergence of many different solution techniques proposed for resource constrained construction scheduling problems. High majority of these solutions involve metaheuristic techniques. Almost all of the techniques involving metaheuristic techniques are based on the search of the most convenient ordering of activities. In this study, a different approach is applied, namely, the search for the most convenient vector involving the early start days of the activities. This choice necessitated creation of two special operators called left-compression operator and right-compression operator. The use of these operators enabled determination of critical activities and critical paths for the problems with resource constraints. Analyses on example problems have indicated that for a given problem the optimum solution may not be unique, and on the other hand, there may be sub-optimal solutions where all activities are critical. The metaheuristic method used in the study is the Big Bang - Big Crunch Optimization, which could not have been applied to this problem if the vector of unknowns were considered as the ordered set of activities.

Suspected Bacterial Endophthalmitis Following Sustained-release Dexamethasone Intravitreal Implant: A Case Report

Mücella Arıkan Yorgun,Melek Mutlu,Yasin Toklu,Hasan Basri Çakmak,Nurullah Çağıl 대한안과학회 2014 Korean Journal of Ophthalmology Vol.28 No.3

A 58-year-old man admitted to our opthalmology department with the complaint of branch retinal veinocclusion. He was treated with intravitreal Ozurdex in the right eye. Two days after the injection, the patientpresented with ocular pain and the visual acuity was hand movement. A diagnosis of endophthalmitiswas made. We performed emergent pars plana vitrectomy (PPV) and the implant was removed fromthe vitreous cavity using a retinal forceps. A combination of vancomycin 1.0 mg and amikacin 0.4 mgwas injected intravitreally. However, because of the blurring in the vitreus one week after the procedure,phacoemulsification and a repeat PPV was performed. Five days after the last procedure the signs andsymptoms of endophthalmitis were resolved. Our case demonstrated that endophthalmitis could developafter intravitreal implantation of Ozurdex. Surgical removal of the implant and immediate vitrectomy seemsto be a useful treatment option in these cases.

Is Hyperbaric Oxygen Therapy Effective in Cisplatin-Induced Ototoxicity in Rats?

H. Bengu Cobanoglu,Erkan Vuralkan,Abdullah Arslan,Bengusu Mirasoglu,A. Savas Toklu 대한이비인후과학회 2019 Clinical and Experimental Otorhinolaryngology Vol.12 No.1

Objectives. Cisplatin is an antineoplastic agent, used in the treatment of different types of malignant neoplasms. Side effects such as ototoxicity, nephrotoxicity, and bone marrow toxicity are the main limitations of its clinical use. The aim of the present study was to evaluate the possible effects of hyperbaric oxygen (HBO) therapy as a protective agent in cisplatin-induced ototoxicity in rats. Methods. A total of 30 adult Wistar rats (60 ears) were divided into five equal groups. Group 1 is a control group; group 2 is HBO therapy group; group 3 received 15 mg/kg cisplatin intraperitoneally; group 4 received 15 mg/kg cisplatin intraperitoneally and HBO treatment on the same day; group 5 received 15 mg/kg cisplatin intraperitoneally and HBO treatment 72 hours later. The effect of ototoxicity was measured with distortion product otoacoustic emission testing performed on the days 1, 3, and 7. Results. Groups 4 and 5 that received HBO treatment after cisplatin had better signal-to-noise ratio (SNR) values compared with group 3 that received only cisplatin (P<0.05). Compared with group 5, group 4 (same day HBO treatment) had better SNR values (P<0.05). Conclusion. HBO was found effective for prevention of cisplatin-induced ototoxicity in rats. Our study differs from other studies regarding using a promising treatment, which does not expose subjects to extra stress.

Comparison of Metabolic and Anatomic Response to Chemotherapy Based on PERCIST and RECIST in Patients with Advanced Stage Non-small Cell Lung Cancer

Ordu, Cetin,Selcuk, Nalan A.,Akosman, Cengiz,Eren, Orhan Onder,Altunok, Elif C.,Toklu, Turkay,Oyan, Basak Asian Pacific Journal of Cancer Prevention 2015 Asian Pacific journal of cancer prevention Vol.16 No.1

Background: The aim of this study was to explore the prognostic role of metabolic response to chemotherapy, determined by FDG-PET, in patients with metastatic non-small-cell lung cancer (NSCLC). Materials and Methods: Thirty patients with metastatic NSCLC were analyzed for prognostic factors related to overall survival (OS) and progression free survival (PFS). Disease evaluation was conducted with FDG-PET/CT and contrast-enhanced CT prior to and at the end of first-line chemotherapy. Response evaluation of 19 of 30 patients was also performed after 2-3 cycles of chemotherapy. Morphological and metabolic responses were assessed according to RECIST and PERCIST, respectively. Results: The median OS and PFS were 11 months and 6.2 months, respectively. At the end of first-line chemotherapy, 10 patients achieved metabolic and anatomic responses. Of the 19 patients who had an interim response analysis after 2-3 cycles of chemotherapy, 3 achieved an anatomic response, while 9 achieved a metabolic response. In univariate analyses, favorable prognostic factors for OS were number of cycles of first-line chemotherapy, and achieving a response to chemotherapy at completion of therapy according to the PERCIST and RECIST. The OS of patients with a metabolic response after 2-3 cycles of chemotherapy was also significantly extended. Anatomic response at interim analysis did not predict OS, probably due to few patients with anatomic response. In multivariate analyses, metabolic response after completion of therapy was an independent prognostic factor for OS. Conclusions: Metabolic response is at least as effective as anatomic response in predicting survival. Metabolic response may be an earlier predictive factor for treatment response and OS in NSCLC patients.