Yazar "Akcan, Serap" seçeneğine göre listele
Listeleniyor 1 - 5 / 5
Sayfa Başına Sonuç
Sıralama seçenekleri
Öğe A new approximation for inventory control system with decision variable lead-time and stochastic demand(2013) Akcan, Serap; Kokangül, AliDemand for any material in a hospital depends on a random arrival rate and random length of stay in units. Therefore, the demand for any material shows stochastic characteristics that make determining the optimum level of r and Q problem more difficult. Thus, in this study, a single item inventory system for healthcare was developed using a continuous review (r, Q) policy. A simulation meta-model was constructed to obtain equations for the average on-hand inventory and average number of orders per year. Then, the equations were used to determine the optimal levels of r and Q while minimizing the total cost in an integer non-linear model. The same problem investigated in this study was also solved using OptQuest optimization software. © INTERNATIONAL JOURNAL OF INDUSTRIAL ENGINEERING.Öğe Determining process capability ındices for shirting fabric(Çukurova Üniversitesi, 2016) Akcan, SerapŞirketler düzenli üretim yapabilmek için ürettikleri ürünlerin spesifikasyon limitleri dahilinde üretilmesini arzu ederler. Proses yeterlilik indeksleri Cp (proses potansiyel indeksi) ve Cpk (proses yeterlilik indeksi) yeterlilik ölçümleri için kullanılır. Bu çalışmada, Türkiye’de gömleklik kumaşlar üreten bir tekstil fabrikasında proses yeterlilik analizi ve proses yeterlilik indeksleri tartışılmıştır. Bu fabrikada, fire kumaş miktarının üretim yöneticisi tarafından belirlenen üst sınırı aşmaması arzu edilmektedir. Eğer fire kumaş miktarı artarsa, memnun olmayan müşteri sayısında da artış olacaktır. Ve bu durum, fabrika için artan maliyete ve azalan rekabet gücüne sebep olacaktır. Bu sebeple, bu tekstil fabrikası için Cp ve Cpk indeksleri hesaplanmıştır. Çalışmanın sonucunda, incelenen tekstil fabrikasında prosesin yetersiz olduğu ve fire kumaş miktarının azaltılması için bazı önlemlerin alınması gerektiği görülmüştür. Ayrıca, fire kumaşa sebep olan kumaş hataları ve sürecin yetersizliği sebepleri de araştırılmıştır.Öğe Optimizing nurse capacity in a teaching hospital neonatal intensive care unit(SPRINGER, 2017) Kokangül, Ali; Akcan, Serap; Narlı, MüfidePatients in intensive care units need special attention. Therefore, nurses are one of the most important resources in a neonatal intensive care unit. These nurses are required to have highly specialized training. The random number of patient arrivals, rejections, or transfers due to lack of capacity (such as nurse, equipment, bed etc.) and the random length of stays, make advanced knowledge of the optimal nurse a requirement, for levels of the unit behave as a stochastic process. This stochastic nature creates difficulties in finding optimal nurse staffing levels. In this paper, a stochastic approximation which is based on the required nurse: patient ratio and the number of patients in a neonatal intensive care unit of a teaching hospital, has been developed. First, a meta-model was built to generate simulation results under various numbers of nurses. Then, those experimented data were used to obtain the mathematical relationship between inputs (number of nurses at each level) and performance measures (admission number, occupation rate, and satisfaction rate) using statistical regression analysis. Finally, several integer nonlinear mathematical models were proposed to find optimal nurse capacity subject to the targeted levels on multiple performance measures. The proposed approximation was applied to a Neonatal Intensive Care Unit of a large hospital and the obtained results were investigated.Öğe Time series analysis models for estimation of greenhouse gas emitted by different sectors in Turkey(TAYLOR & FRANCIS INC, 2018) Akcan, Serap; Kuvvetli, Yusuf; Koçyig?it, HikmetDue to the increasing global warming in the world, analyzing greenhouse gas emissions is a crucial issue. This study has examined greenhouse gas emissions in Turkey according to energy sector, industrial processes sector, agriculture sector and waste sector. Then, time series analysis models are used to estimate greenhouse gas emissions based on sectors. Models' performances are tested using mean error, mean absolute error and root mean square error. The results show that forecasting models have a good potential to estimate the national greenhouse gas emissions for different sector within a reasonable error. The study results will help organize and estimate the national greenhouse gas emissions inventory.Öğe Wind speed forecasting using time series analysis methods(Çukurova Üniversitesi, 2017) Akcan, SerapAs a natural, non-consumable, clean and sustainable energy resource, wind energy is becoming crucial throughout the world. Forecasting wind speed is noteworthy to design and install wind power stations. In this study, several time series analysis methods for wind energy were compared considering long-termmonthly-average wind speed data between the years of 1960 and 2014 at nine meteorological stations throughout five geographical areas in Turkey. The low performance measure values seen in results indicate that the methods used in this study can be forecast for wind speed.
