Hastane sistemlerinde çoklu malzeme durumu için simülasyon meta-modellemeye dayalı stok optimizasyonu

TEZ7813Tez (Doktora) -- Çukurova Üniversitesi, Adana, 2010.Kaynakça (s. 153-159) var.xi, 174 s. : res. ; 29 cm.In first stage of this study, a single-item inventory system for hospital systems was studied using a continuous review (r, Q) policy. Demand for any material of patients in a hospital depends on random arrival rate and random length of stay in units. Therefore, the demand for any material is a stochastic process. This stochastic process makes determining optimal levels for r and Q more difficult. In this study, a simulation meta-model is constructed to obtain equations for the average on hand inventory and average number of orders per year. Then, the optimal levels of r and Q, which minimize the total cost, are obtained using an integer non-linear model and a case study is presented. In second stage, inventory problem for multiple-item case in hospital systems was investigated by combining the continuous and periodic control policies under the stochastic demand and instantaneous lead time. Finally, distribution of demand during lead time was obtained both using analytical approach and simulation model under stochastic demand and lead time. The model was enhanced to determine the reorder quantities of different service levels.Çalışmanın ilk aşamasında hastane sistemlerinde tek malzemeli envanter sistemi sürekli kontrol envanter politikası (r, Q) kullanılarak çalışılmıştır. Bir hastanede herhangi bir malzemeye olan hastaların talebi ünitelerdeki rassal geliş oranına ve rassal yatış süresi oranına bağlıdır. Bu da malzemeye olan ihtiyaç miktarının stokastik bir süreç göstermesine neden olur. Bu stokastik süreç r ve Q düzeylerinin belirlenmesi problemini oldukça zorlaştırır. Bu çalışmada, ortalama elde bulundurulan malzeme miktarı ve ortalama yıllık sipariş sayısı fonksiyonlarının elde edilmesi amacıyla birim hasta için günlük malzeme tüketim, hasta geliş ve hasta yatış dağılımları kullanılarak simülasyon meta-model kurulmuştur. Daha sonra, toplam maliyeti minimize edecek optimum r ve Q düzeyleri tamsayılı non-lineer matematiksel modelleme kullanılarak elde edilmiş ve bir örnek olay incelemesi sunulmuştur. İkinci aşamada ise hastane sistemlerinde çoklu malzeme durumu için envanter problemi stokastik talep ve anlık tedarik süresi koşullarında sürekli ve periyodik kontrol politikalarının birleşimi ile incelenmiştir. Çalışmada son olarak, stokastik talep ve stokastik tedarik süresi durumunda tedarik süresince oluşan talebin dağılımı hem analitik olarak hem de simülasyon modeli ile elde edilmiştir. Model, farklı servis düzeylerinde tekrar sipariş verme miktarlarının belirlenmesi ile zenginleştirilmiştir.Bu çalışma Ç.Ü. Bilimsel Araştırma Projeleri Birimi tarafından desteklenmiştir. Proje No: MMF2006D22

Gömleklik kumaş için proses yeterlilik indekslerinin belirlenmesi

Şirketler 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.Organizations use process capability analysis to produce their products within specification limits for regular manufacturing. Process capability indices, Cp (process potential indices) and Cpk (process capability indices), are used as capability measures. In this study, process capability analysis and process capability indices are discussed in the context of a textile factory that produces shirting fabrics in Turkey. In this factory, it is desired that the amount of wastage fabric does not exceed the upper limit that identified from production manager. If the amount of wastage fabric increases, the number of unsatisfied customers will also increase. And, this situation is caused increasing cost and decreasing competitiveness for factory. For these reasons, Cp and Cpk indices were calculated for the textile factory. As a consequence of this study, we discovered that the process was inadequate precautions must be undertaken to decrease the amount of wastage fabric. Furthermore, the fabric faults which cause wastage fabric and the reasons for the process’ inadequacies were also investigated

Zaman serisi analiz metotları kullanılarak rüzgâr hızının tahmin edilmesi

As 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.Doğal, tükenmeyen, temiz ve sürdürülebilir bir enerji kaynağı olduğundan rüzgâr enerjisi dünyada önem kazanmaktadır. Rüzgâr enerjisi istasyonlarının tasarlanması ve kurulması için rüzgâr hızı tahmini önemlidir. Bu çalışmada, Türkiye’deki beş farklı coğrafi bölge ve dokuz meteorolojik istasyondan 1960 ve 2014 yılları arasındaki uzun dönemli aylık ortalama rüzgâr hızı verileri dikkate alınarak rüzgâr enerjisi için farklı zaman serisi analizi metotları karşılaştırılmıştır. Çalışmanın sonucunda elde edilen düşük performans ölçüm değerleri, rüzgâr hızı tahminleri için bu çalışmada ele alınan metotların kullanılabileceğini göstermektedir

Lojistik bilişim sistemlerinin değerlendirilmesine yönelik bir uzman sistemi

TEZ4632Tez (Yüksek Lisans) -- Çukurova Üniversitesi, Adana, 2003.Kaynakça (s. 122-127) var.viii, 127[50] s. ; 30 cm.

A NEW APPROXIMATION FOR INVENTORY CONTROL SYSTEM WITH DECISION VARIABLE LEAD-TIME AND STOCHASTIC DEMAND

Demand 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

Integrated Multicriteria Decision-Making Methods to Solve Supplier Selection Problem: A Case Study in a Hospital

In supply chain literature, supplier evaluation and selection problem is one of the most studied subjects because of the significant roles of suppliers in terms of the chain’s sustainability and profitability. Therefore, it is important for organizations to adopt a systematic way to evaluate and select the best supplier according to their respective criteria in today’s competitive environment. Multicriteria decision-making methods provide for this need of organizations because determination of an appropriate supplier selection is a multicriteria decision-making (MCDM) problem essentially. Although a lot of applications of these methods for supplier evaluation and selection can be seen in the literature, studies in the health-care sector are insufficient. Hospitals in the health-care sector also have to consider their supplier-related decisions to decrease risks and threads which affect their effectiveness. The aim of this study was to fill this gap by providing different hybrid models for selecting the best supplier for hospitals. Supplier evaluation and selection process start with recognizing the related criteria according to the studies in the literature. Analytic hierarchy process (AHP) method is deployed to weight the criteria, and suppliers are listed via technique for order preference by similarity to ideal solution (TOPSIS), elimination and choice translating reality English (ELECTRE), grey relational analysis (GRA), and simple additive weighting (SAW) methods. The main aim of this study was to present different hybrid MCDM methods and show their efficiency and consistency with each other. In this study, hybrid multicriteria decision-making models (AHP-TOPSIS, AHP-ELECTRE, AHP-GRA, and AHP-SAW) are presented and compared. The results show that the presented hybrid methods in this study are consistent with each other and give the same ranking for the selection of the best supplier. It can be considered as a useful guideline for hospitals.</jats:p

A new approximation for inventory control system with decision variable lead-time and stochastic demand

Demand 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

Process capability analysis a machining company

Üretim proseslerinde ürünlerin spesifikasyon limitleri içerisinde üretilmesi istenmektedir. Bu hedef proses yeterliliği ile basarılabilir. Proses yeterliliğini belirlemede Cp ve Cpk indeksleri kullanılmaktadır. Bu çalısmada, silindir gömleği üreten orta ölçekli bir isletmenin talaslı üretim hattında proses yeterlilik analizi yapılmıs ve yeterlilik indeksleri (Cp ve Cpk) hesaplanmıstır. Yapılan analiz sonucunda isletmenin proses yeterliliğinin “yeterli olmadığı” görülmüstür. ?sletmenin proses yeterliliğini sağlayabilmesi için proses değiskenliğini azaltıcı önlemler alması gerekmektedir.In manufacturing process, the products are wanted to be produced within specification limits. This goal can be achieved by process capability. Cp and Cpk indices are used for determining the process capability. In this study, process capability analysis have been done in machining line of a medium sized company which produces cylinder liner, and process capability indices (Cp and Cpk ) have been calculated. As a result of analysis, it has been seen that the process is not adequate. In order to satisfy the process capability, company must take actions to reduce the process variability

Integrated Multicriteria Decision-Making Methods to Solve Supplier Selection Problem: A Case Study in a Hospital

In supply chain literature, supplier evaluation and selection problem is one of the most studied subjects because of the significant roles of suppliers in terms of the chain's sustainability and profitability. Therefore, it is important for organizations to adopt a systematic way to evaluate and select the best supplier according to their respective criteria in today's competitive environment. Multicriteria decision-making methods provide for this need of organizations because determination of an appropriate supplier selection is a multicriteria decision-making (MCDM) problem essentially. Although a lot of applications of these methods for supplier evaluation and selection can be seen in the literature, studies in the health-care sector are insufficient. Hospitals in the health-care sector also have to consider their supplier-related decisions to decrease risks and threads which affect their effectiveness. The aim of this study was to fill this gap by providing different hybrid models for selecting the best supplier for hospitals. Supplier evaluation and selection process start with recognizing the related criteria according to the studies in the literature. Analytic hierarchy process (AHP) method is deployed to weight the criteria, and suppliers are listed via technique for order preference by similarity to ideal solution (TOPSIS), elimination and choice translating reality English (ELECTRE), grey relational analysis (GRA), and simple additive weighting (SAW) methods. The main aim of this study was to present different hybrid MCDM methods and show their efficiency and consistency with each other. In this study, hybrid multicriteria decision-making models (AHP-TOPSIS, AHP-ELECTRE, AHP-GRA, and AHP-SAW) are presented and compared. The results show that the presented hybrid methods in this study are consistent with each other and give the same ranking for the selection of the best supplier. It can be considered as a useful guideline for hospitals