Strength properties of slag/fly ash blends activated with sodium metasilicate

U radu se analizira alkalno aktiviranje mješavina morta koje sadrže mljevenu granuliranu zguru iz visokih peći i leteći pepeo, pri čemu se aktivacija odvija pomoću natrijevog metasilikata. Analiziraju se dvije serije te je izmjerena tlačna čvrstoća. Rezultati dobiveni za prvu seriju pokazuju da se tlačna čvrstoća bitno smanjuje sa smanjenjem omjera zgure i letećeg pepela. Trodnevna tlačna čvrstoća morta njegovanog pri temperaturi 100 °C donekle se povećava do omjera 60/40, ali se bitno smanjuje pri omjeru 40/60.The alkali activation of mortar blends containing Ground Granulated Blast Furnace Slag and Fly Ash, with activation based on sodium metasilicate, is investigated in this study. Two series are investigated, and compressive strength is measured. The results of the first series show that the compressive strength decreases considerably with a decrease in the slag and fly ash ratio. The 3-day compressive strength of mortar cured at the temperature of 100°C increases slightly up to the ratio of 60/40, but decreases considerably at the 40/60 ratio

Optimizing Demand Management in Stochastic Systems to Improve Flexibility and Performance

In this thesis we analyze optimal demand management policies for stochastic systems. In the first system considered, a manufacturer decides how to manage demand from customers that differ in their priority level and willingness to pay. He has limited production capacity and predetermined prices throughout the horizon. We find an optimal production and inventory strategy that rations current and future limited capacity between customer classes through reserving inventory for the future and accepting orders now for future delivery. Next, we extend these results to the case when the customers have different tolerance to delayed fulfillment, namely, first-class customers never accept backlogging whereas second-class customers agree to wait one period for a discount. We find an optimal policy similar to the production and inventory strategy that is used for the first system based on threshold values. The third system considers a firm whose recent performance in meeting quoted leadtimes affects future demand arrivals. We assume that the probability of a customer placing an order depends on the quoted leadtime, and both customer arrivals and processing times are stochastic. When capacity of the firm is infinite, we find the optimal leadtime to quote, and when capacity is finite and leadtime is industry-dictated, we determine that the optimal demand acceptance policy does not necessarily have a nice structure. We comment on the structure of the optimal policy for a special case and develop several heuristics for the general case. The final system considered in this thesis is the Sports and Entertainment industry, where demand is managed for a season of several performances by selling season tickets initially and single events later in the selling horizon. We specifically study the optimal time to switch between these market segments dynamically as a function of the state of the system and show that the optimal switching time is a set of time thresholds that depend on the remaining inventory and time left in the horizon.Ph.D.Committee Chair: Julie L. Swann; Committee Member: Hayriye Ayhan; Committee Member: Mark Ferguson; Committee Member: Paul M. Griffin; Committee Member: Pinar Keskinoca

Spor Ve Eğlence Sektöründe Birden Fazla Organizasyonun Paket Halinde Satılma Methodları

Bu çalışmada maç / organizasyonların zamanları ve fikstür etkisi göz önüne alındığında hangi oyunların sezon / kombine biletler içine dahil edilmesinin geliri en fazla miktarda arttıracağı incelenecektir. Temel olarak çalışma iki bölüm şeklinde düşünülebilir: 1- Belirlemiş bir fikstür için geliri en çok arttıracak şekilde hangi maç / organizasyonların gruplanarak sezon / kombine biletler olarak satılması gerektiğinin belirlenmesi; 2- Geliri en çok arttıracak maç / organizasyon gruplamasının ve fikstürün beraber belirlenmesi. İlk bölümde çalışılacak problem kararlaştırılmış bir fikstür içinde hangi maç / organizasyonların gruplanarak satılması gerektiğini belirleme problemidir. Bu gruplamayı etkileyen faktörler organizasyonların talepleri, tekli bilet fiyatları, salonun / stadın toplam kapasitesi, maç ve organizasyonların fikstürdeki sıralaması ve son olarak farklı bilet satış dönemleridir. Bunların dışında ise yine önemli bir faktör gruplamanın içinde kaç organizasyonun yer alacağı bilgisidir. Bu miktar üzerine bir sınır konulmadığı takdirde çözülecek problem kombinatoriyel bir problem olmakta ve bu durum çözümün yapısını oldukça zorlaştırmaktadır. İkinci bölümde çalışılacak problem, maç / organizasyonların fikstürünü toplam geliri en fazla yapacak şekilde belirleme problemidir. İlk probleme kıyasla fikstür belirleme ve grup belirleme aşamalarında çok daha fazla kombinasyon olacağı için problemin zorluğu önemli miktarda artmaktadır. Literatürde çalışılmış olan fikstür belirleme problemi daha çok belirli kısıtlar altında olurlu (feasible) bir fikstür belirlemek üzereyken, bu çalışmanın amacı toplam geliri en fazla yapacak fikstürü belirlemek olacaktır. Dolayısı ile önerilecek yöntemlerin literatürde çalışılan yöntemlerden oldukça farklı olması beklenmektedir. Bu çalışma ile spor ve eğlence sektöründe bilet satış planlaması yapan yöneticiler tarafından kullanılabilecek esasların oluşturulması amaçlanmaktadır

Financial and Management Accounting

Basics of financial accounting. Preparation of balance sheet, income statement and flow of funds statement. Inventory valuation and depreciation methods. Basics of accounting. Definition of costs. Absorption cost techniques, with an emphasis on allocation of overhead in manufacturing organizations

Engineering Economy And Cost Analysis II

This course is mainly concerned with economic analysis for engineering and managerial decision making. It consists of techniques for evaluating the worth of prospective projects, investment opportunities and design choices

Effects of Natural Disaster Trends: A Case Study for Expanding the Pre-Positioning Network of CARE International

The increasing number of natural disasters in the last decade necessitates the increase in capacity and agility while delivering humanitarian relief. A common logistics strategy used by humanitarian organizations to respond this need is the establishment of pre-positioning warehouse networks. In the pre-positioning strategy, critical relief inventories are located near the regions at which they will be needed in advance of the onset of the disaster. Therefore, pre-positioning reduces the response time by totally or partially eliminating the procurement phase and increasing the availability of relief items just after the disaster strikes. Once the pre-positioning warehouse locations are decided and warehouses on those locations become operational, they will be in use for a long time. Therefore, the chosen locations should be robust enough to enable extensions, and to cope with changing trends in disaster types, locations and magnitudes. In this study, we analyze the effects of natural disaster trends on the expansion plan of pre-positioning warehouse network implemented by CARE International. We utilize a facility location model to identify the additional warehouse location(s) for relief items to be stored as an extension of the current warehouse network operated by CARE International, considering changing natural disaster trends observed over the past three decades

Switching Times from Season to Single Tickets

In this paper, we developed the basic problem with only one switch from selling bundles to selling single tickets to a new version where “early switch to the low-demand event” is also allowed. The resulting policy is defined by a set of threshold pairs of times and remaining inventory, which determine the timing of the optimal switches

Pre-Positioning Disaster Response Facilities and Relief Items

Large-scale disasters cause enormous damage to people living in the affected areas. Providing relief quickly to the affected is a critical issue in recovering the effects of a disaster. Pre-disaster planning has an important role on reducing the arrival time of relief items to the affected areas and efficiently allocating them. In this study, a mixed integer programming model is proposed in order to pre-position warehouses throughout a potential affected area and determine the amount of relief items to be held in those warehouses. Time between the strike of the disaster and arrival of relief items at the affected areas is aimed to be minimized. In addition, using probabilistic constraints, the model ensures that relief items arrive at affected areas within a certain time window with certain reliability. Considering instable fault lines on which Istanbul is located, the proposed model is applied to the Istanbul case for pre-positioning warehouses a priori to the possible expected large-scale earthquake

Dynamically Switching among Bundled and Single Tickets with Time-Dependent Demand Rates

The most important market segmentation in sports and entertainment industry is the competition between customers that buy bundled and single tickets. A common selling practice is starting the selling season with bundled ticket sales and switching to selling single tickets later on. The aim of this practice is to increase the number of customers that buy bundles, which in return increases the load factor of the events with low demand. In this paper, we investigate the effect of time dependent demand on dynamic switching times from bundled to single ticket sales and the potential revenue gain over the case where the demand rate of events is assumed to be constant with time