Comparative Analysis of Incumbent and Emerging Liquefied Natural Gas Regasification Technologies

Energy plays a fundamental role in both manufacturing and services, and natural gas is quickly becoming a key energy source worldwide. Facilitating this emergence is the expanding network of ocean-going vessels that enable the matching of natural gas supply and demand on a global scale by transporting it in the form of liquefied natural gas (LNG) for eventual regasification at its destination. Until very recently only one type of technology has been available for transporting and regasifying LNG: Conventional LNG vessels and land based LNG regasification. It is now possible to transport and regasify LNG onboard special LNG vessels. Companies such as Excelerate Energy and Höegh LNG are currently developing LNG supply chains based on this new technology. Motivated by this recent development we engaged executives at Excelerate Energy to develop and apply to data an integrated analytic framework to compare these incumbent and emerging technologies. Our analysis brings to light basic principles delineating when to deploy each technology and how to configure the emerging technology. Some of our findings challenge conventional wisdom on the role to be played by the emerging technology; others provide answers to open questions faced by companies currently engaged in the commercial deployment of this technology. In addition, our integrated analytic framework has potential relevance for the evaluation of new technologies beyond this specific application

An Analytical Approximation for the Throughput of a Closed Fork/Join Network with Multi-Station Input Subnetworks

Fork/join stations are used for modeling synchronization between entities, and fork/join queueing networks are natural models for a variety of communication and manufacturing systems: Parallel computer networks, fabrication/assembly systems, supply chains and material control strategies for manufacturing systems. Exact solutions of general fork/join networks can only be obtained by using numerical methods to analyze the underlying Markov chains. However, this method is computationally feasible only for networks with small population size and number of stations. In this paper, we present a simple approximation method to estimate the throughput of a closed queueing network that features a single fork/join station receiving inputs from multi-station subnetworks. Our technique uses aggregation to estimate the arrival process from input subnetworks. Given the estimated arrival process, we then derive closed form approximate expression for the network throughput by analyzing a simplified Markov chain. A numerical study shows that the proposed approximation is fairly effective, particularly for large network sizes

OM Practice--Balancing Risk and Efficiency at a Major Commercial Bank

Check processing institutions are being forced to downsize their workforce to cut cost and improve the efficiency of their operations as a result of continued growth of electronic payments, a consequence of the increasing popularity of debit/credit cards and use of online banking. For these institutions, these events are making more urgent the decision of how to staff a check-clearing house to trade off efficiency and the expected costs associated with the risks of delayed checks, which include fraud and float costs. In this paper, we discuss how a team of executives at a major commercial bank (CB) and Carnegie Mellon University students and faculty engaged in conducting a model-based study of the CB check-clearing operations. This project culminated in the development of a simulation optimization model to systematically analyze the nature of the highlighted risk efficiency trade-off at CB. The firm used the model recommendations to obtain operations downsizing guidelines for its senior managers during the implementation of a strategic workforce reduction program at their check-clearing house. The managerial insights from the team analysis, and the specific model-based recommendations, enabled CB executives to balance risk and efficiency while planning the reduction of their check-processing workforce.check processing, workforce sizing, worker cross-training, cost of risk, simulation optimization, math-programming-based lower bound, empirical research

Nervus peroneus superficialis ve uç dallarının Türkiye'de bulunan yenidoğan fetuslardaki varyasyonları

AMAÇ: Nervus peroneus superficialis (SPN) ve uç dallarının ayak ve bacaktaki topografik anatomisi hakkında daha detaylı bilgi vermek amacıyla Türkiye'deki yenidoğan fetuslar üzerinde bu çalışma gerçekleştirildi. YÖNTEM ve GEREÇ: Yirmi yenidoğan kadavrasında her iki alt ekstremite diseke edildi. SPN'nin bacağın anterolateral yüzündeki seyri ve uç dallarının ise ayağın dorsal yüzündeki seyri araştırıldı. BULGULAR: Nervus peroneus superficialis'in, vakaların %75'inde lateral, %15'inde anterior ve %10'unda ise iki dala ayrılıp her iki kompartmanda seyrettiği gözlendi. SPN ayağın dorsal yüzünde, nervus cutaneus dorsalis medialis (MDCn) ve nervus cutaneus dorsalis intermedialis (IDCn) dallarını veriyordu. Vakaların %82,5'inde MDCn üç, IDCn ise iki uç dala ayrılıyordu. Vakaların %10'unda ise MDCn üç, IDCn ise bir uç dala ayrılıyordu. Diğer %7,5'lik vakada ise MDCn üç, IDCn iki dal veriyor ve IDCN nervus cutaneus dorsalis lateralis ile anastomoz yapıyordu. SONUÇ: Nervus peroneus superficialis'in bacağın anterolateral yüzünde, uç dallarının ise ayağın dorsal yüzündeki seyri çok farklılık göstermektedir. Bu olağan dışı yerleşimlerin tanımlanması cerrahlara SPN ve uç dallarının korunmasında ve belirlenmesinde yardımcı olacaktır.AIM: The topography of the superficial peroneal nerve (SPN) and its terminal branches were studied, with the aim of providing further anatomical details for leg and foot in the Turkish newborn fetuses. MATERIAL and METHODS: Limbs from twenty newborn cadavers were dissected. The course of the SPN on the leg and its terminal branches on the foot were investigated. RESULTS: The SPN was lateral (75%), anterior (15%), or branched in both areas (10%) of the cases. The SPN in the dorsum of the feet branched further into medial dorsal cutaneous nerve (MDCn) and intermediate dorsal cutaneous nerve (IDCn). In 82.5% of the cases the MDCn and the IDCn split into three and two branches, respectively. In 10% of the cases, the MDCn gave off three, and the IDCn one terminal branches. In 7.5% of the cases, the MDCn had three while the IDCn had two branches that communicated with the lateral dorsal cutaneous nerve. CONCLUSION: The course of SPN on the anterolateral surface of the leg and its terminal branches on the dorsal surface of the foot were quite different. This unusual variant location will enable the surgeon to find and preserve the SPN and its terminal branches