Modeling Overstock

Two main problems have been emerging in supply chain management: the increasing pressure to reduce working capital and the growing variety of products. Most of the popular indicators have been developed based on a controlled environment. A new indicator is now proposed, based on the uncertainty of the demand, the flexibility of the supply chains, the evolution of the products lifecycle and the fulfillment of a required service level. The model to support the indicator will be developed within the real options approach.overstock, stock management, real options

Support International Business Expansion with Sequential Reviews

This chapter is about the multinational company’s decision on whether to enter new foreign markets using direct investment, exporting, or developing a local partner for distribution, with the possibility of scaling the investment under different demand levels. The perception of the host market demand does not remain the same during the investment period due to additional information and economic or political reasons. Therefore, the influence of uncertainty can be addressed by recombining a trinomial lattice model with changing uncertainty, to value investments with several interacting options. Overall, in this chapter we enhance the knowledge associated with exploring foreign markets subject to different demand uncertainties, valuing the flexibility of sequential options

PACE: Simple Multi-hop Scheduling for Single-radio 802.11-based Stub Wireless Mesh Networks

IEEE 802.11-based Stub Wireless Mesh Networks (WMNs) are a cost-effective and flexible solution to extend wired network infrastructures. Yet, they suffer from two major problems: inefficiency and unfairness. A number of approaches have been proposed to tackle these problems, but they are too restrictive, highly complex, or require time synchronization and modifications to the IEEE 802.11 MAC. PACE is a simple multi-hop scheduling mechanism for Stub WMNs overlaid on the IEEE 802.11 MAC that jointly addresses the inefficiency and unfairness problems. It limits transmissions to a single mesh node at each time and ensures that each node has the opportunity to transmit a packet in each network-wide transmission round. Simulation results demonstrate that PACE can achieve optimal network capacity utilization and greatly outperforms state of the art CSMA/CA-based solutions as far as goodput, delay, and fairness are concerned

Aplicações do quitosano como biomaterial

Os biomateriais podem ser utilizados para substituir, no todo ou em parte, sistemas biológicos quando estes são impossibilitados de cumprir as suas funções naturais. Atualmente existe uma panóplia de biomateriais que podem ser divididos, de acordo com a sua origem, em materiais naturais e sintéticos. O quitosano consiste num biomaterial natural, hidrófilo, atóxico, biodegradável e biocompatível, produzido por fontes naturais renováveis, cujas propriedades vêm sendo exploradas em aplicações industriais e tecnológicas desde há vários anos. O quitosano é um dos biomateriais com maior potencial de utilização na medicina regenerativa. Desde fios de suturas, a biomateriais de aplicação na pele, osso e cartilagens, o quitosano possui uma panóplia de possibilidades de utilização neste campo. O objetivo deste trabalho de revisão bibliográfica é evidenciar os avanços do quitosano e sua vasta aplicabilidade como biomaterial. A composição do tecido ósseo, tecido cartilaginoso, e a pele, bem como o conceito de biomaterial e quitina serão abordados nas diferentes secções. Por fim, é efetuada uma referência relativa às técnicas de engenharia de tecidos com recurso ao quitosano como, bem como uma avaliação crítica do seu potencial de sucesso, através de exemplos práticos relativos aos seus avanços recentes.Biomaterials can be used to replace, in whole or in part, biological systems when they are unable to comply with its natural functions. Currently there is a range of biomaterials that can be divided, according to its origin, in natural and synthetic materials. Chitosan is a natural biomaterial, hydrophilic, non-toxic, biodegradable and biocompatible, produced from renewable natural sources, whose properties have been explored in industrial and technological applications for several years. Chitosan is one of the biomaterials with potential for use in regenerative medicine. Since sutures, up to application of biomaterials in the skin, bone and cartilage, the chitosan has a range of potential uses in this field. The objective of this literature review is to highlight the progress of chitosan and his extensive applicability as a biomaterial. The composition of bone, cartilage, and skin, as well as the concept of biomaterial and chitin are discussed in different sections. Finally, a reference on of tissue engineering techniques using chitosan, as well as a critical evaluation of their potential for success through practical examples relating to its recent advances

Blind Prediction of a Full-Scale RC Bridge Column Tested Under Dynamic Conditions

The definition of appropriate modelling approaches combined with a consistent software framework is a topic of major importance in the present days for structural engineering in general and, particularly, for earthquake engineering. The accuracy of the results obtained in the recent “Concrete Column Blind Prediction Contest 2010” for a full-scale reinforced concrete bridge column tested on the NEES Large High-Performance Outdoor Shake Table, seems to indicate that current modelling strategies are on the right track. The 1.2 m diameter cantilevered column spans 7.2 m from the footing. A massive 230 tonne reinforced concrete block supported by the column generates the inertial forces to mobilize the column capacity. Seismic performance was investigated under 6 ground motions, starting with lowintensity shaking and bringing the column progressively to near-collapse conditions. Based on the obtained results from the pre-contest simulation, as well with the post-contest analysis, it was possible to extract some important conclusions regarding the application of several strategies, namely the use of different type elements, element discretization, constitutive laws for materials.N/

Exploring modes of entry into international markets: direct investment or contractual relations

We consider the multinational company's decision on whether to enter a new foreign market using direct investment by establishing a subsidiary, direct exporting or contracting a local distributor, with the option to invest later. We develop two models, based on the real options theory, to support such decisions. The option on direct exporting or on a local distributor allows the firm to minimize risks by finding out if the market is large enough to support future direct investment. We find the direct investment to be the desirable mode of entry in large markets subject to low demand uncertainty. Overall, the investigation increases the knowledge related with exploring new markets subject to demand uncertainty, valuing the flexibility of present and future options

Interstory drift based scaling of earthquake ground motions

A novel amplitude scaling procedure is proposed in this study where the ground motion scaling factors are defined as the ratio of interstory drift distributions under target spectrum versus under the associated ground motion spectrum. The advantage of employing interstory drift ratio in ground motion scaling, compared to employing spectral intensity directly, is that it provides a strong theoretical link between the target spectrum intensity and the fundamental dynamic characteristics of the structure. Hence, scaling is conditioned on structural response, which is in turn a function of seismic intensity. The interstory drift-based scaling procedure (IDS) is presented herein for planar frames for brevity. Accuracy and efficiency of the IDS procedure is assessed under a set of near fault strong motions from large magnitude events. The results revealed that the proposed procedure is accurate since the resulting bias in estimating linear elastic interstory drifts is negligibly small. Further, it is noticeably more effective as compared to the conventional procedures suggested in recent seismic codes, yet it is simpler

Effects of the ratio of porosity to volumetric cement content on the unconfined compressive strength of cement bound fine grained soils

This paper presents an experimental investigation into the effects of porosity, dry density and cement content on the unconfined compressive strength and modulus of elasticity of cementbound soil mixtures. A clayey sand was used with two different proportions of type IV Portland cement, 10% and 14% of the dry mass of the soil. Specimens were moulded with the same water content but using four different compaction efforts, corresponding to four different dry densities. Unconfined compression testing was conducted at seven days of curing time on unsoaked samples. The results showed that the compressive strength increased with the increase in cement content and with the decrease in porosity. From the experimental data, a unique relationship was found between the unconfined compressive strength and the ratio of porosity to volumetric cement content for all the mixtures and compaction efforts tested. The equation developed demonstrates that it is possible to estimate the amount of cement and the dry density to achieve a certain level of unconfined compressive strength. A normalized general equation was also found to fit other authors’ results for similar soils mixed with cement. From this, a cement-bound soil model was proposed for the development of a mixing design procedure for different soils.publishersversionpublishe

Analysis Issues on Seismic Assessment of Existing Structures

Many existing RC structures worldwide were designed for gravity loads only, with inadequate lateral load resistance, lateral stiffness and poor detailing of the reinforcement. Moreover, the concept of regularity both in plan and elevation that characterise a good conceptual design was, in most cases, not taken into account. The introduction in Europe of the regulations for seismic assessment of existing structures imposed stricter performance requirements for building structures. In order to take into account the poor seismic behaviour of such buildings, recent seismic codes – namely EC8 and NTC08, introduce a number of prescriptions regarding issues such as analysis type, load distribution, accidental eccentricity, etc. At the same time, these codes give room for engineering judgment to be used with reference to the definition of structural and non-structural elements such as slabs or infill walls, and obviously leave it up to the analyst decisions regarding Finite Elements typology, meshing, mass modelling, etc. The main goal of this work is thus to provide an extensive and wide evaluation on the influence of each of the abovementioned parameter on the seismic assessment of structures. For this purpose, nonlinear static analysis, as well as nonlinear dynamic analysis are performed on a real building that has also been experimentally tested in the past. The results will hopefully provide indications on the relative importance of each modelling parameter or decision.N/