364 research outputs found
Managing uncertainty in regional supply chains: The case of Fresh fruit from Lleida province
Supply chain management typically examines a network of companies from production to consumption with the aim to improve performance in terms of cost. During the last decades, supply chain management has evolved to include multi-objective performance measurement goals such as flexibility, reliability, and recently sustainability. In food supply chains sustainability is measured with CO2 emissions and other environmental indicators. However, there are two gaps in our understanding of managing supply chains effectively. Firstly, uncertainty is a key factor that influences the performance of chains. Although, scholars such as van der Vorst and Beulens (2002) have early identified uncertainty as a key parameter in supply chains, there is little empirical evidence on how to model it effectively. This is surprising since supply chains are prone to complexity and uncertainty. Therefore, making well-informed supply chain decisions requires risk analysis, control and mitigation (Heckmann, 2015). According to van der Vorst and Beulens (2002), there are three characteristics of supply chain uncertainty: - Inherent characteristics: variability in demand, supply or process are extremely common in perishable product chains. - Chain characteristics: chain configuration, such consolidation points, may disturb the system. - Exogenous phenomena: they are not controllable by the firm. This category includes weather conditions, governmental regulations, etc. Solutions to such increasing inventory, adding capacity at different locations and having multiple suppliers — undermine efforts to improve supply chain cost efficiency (Sunil, 2014) The second gap in our understanding food supply chains lies on the methods applied where the unit of analysis is usually the firm-level or in fewer studies the dyad between suppliers and retailers. Only but few studies, have examined the region as unit of analysis in food supply chains (Soysal et al. 2014) This study aimed to examine the regional supply chains and assess how uncertainly affects their performance. The method was a case study of Fresh fruit from Lleida province. Data collection included site visits, interviews with key managers and secondary data sources. The study modeled the fruit supply chains from Lleida to EU destinations. It analyses the key risk factors that influence decision making. The study sheds light how regions compete in global supply chains which is significant especially after the Brexit outcome. A number of recommendations and suggestions for further research are also provided. References Heckmann, Iris, Tina Comes, and Stefan Nickel. (2015), A critical review on supply chain risk–Definition, measure and modelling, Omega, Vol 52, No. 119-132. Soysal, M., Bloemhof-Ruwaard, J. and van der Vorst, J. (2014). Modelling food logistics networks with emission considerations: The case of an international beef supply chain. International Journal of Production Economics, Vol. 152, pp.57-70. van der Vorst, J. and Beulens, A. (2002). Identifying sources of uncertainty to generate supply chain redesign strategies. International Journal of Physical Distribution & Logistics Management, Vol. 32, No. 6, pp.409-430
Optimum Mechanical Design of Binary Actuators Based on Shape Memory Alloys
This chapter describes the optimum mechanical design of shape memory based actuators. The authors show how to exploit the Shape Memory Alloy (SMA) to design silent, compact and light binary actuators. Two simple mechanical models are considered to describe the SMA behaviour and design equations are provided for two classes of actuators. First SMA actuators are analyzed and designed on the basis of the backup element needed to recover the stroke. Second SMA actuators are improved by adding a compensator system to enhance the output mechanical response, especially in terms of available stroke. Useful design procedures are provided to help the engineer in the synthesis of SMA actuators. Starting from the design specifications, a step by step procedure is built to define the mechanical dimension of the SMA active elements, of the backup system and of the compensator
A Robotic arm for optical and gamma radwaste inspection
We propose Radibot, a simple and cheap robotic arm for remote inspection, which interacts with the radwaste environment by means of a scintillation gamma detector and a video camera representing its light (< 1 kg) payload. It moves vertically thanks to a crane, while the other three degrees of freedom are obtained by means of revolute joints. A dedicated algorithm allows to automatically choose the best kinematics in order to reach a graphically selected position, while still allowing to fully drive the arm by means of a standard videogame joypad
Distance measurement by delayed optical feedback in a ring laser
We numerically study the behavior of a semiconductor ring laser subject to bidirectional
delayed optical feedback, when the isolated laser is in the quasi-unidirectional regime.
The optical feedback, provided by two external refectors located in front of the ring output waveguides, can modify the laser regime produced by the cross-saturation between
the clockwise and the counter-clockwise mode. Thus, the system exhibits new diferent regimes, most of which are asymmetric and bidirectional, with alternating dominant
mode. Two of these regimes are of special interest in view of applications, because the
laser switching period, between the clockwise and the counter-clockwise mode, is linearly
related to the time of fight from the laser to one or both refectors. In these operating conditions, the laser is thus suitable to implement a telemeter. A convenient electrical output
signal is obtained by a photodiode located behind one (partially refecting) fxed mirror,
or by measuring the voltage drop across the laser junction. Simulations are performed by
mathematical models based on rate-equations, assuming typical literature parameters for a
1 mW ring laser
Predictors and outcomes of sustained, intermittent or never achieving remission in patients with recent onset inflammatory polyarthritis:Results from the Norfolk Arthritis Register
Objectives: Early remission is the current treatment strategy for patients with inflammatory polyarthritis (IP) and RA. Our objective was to identify baseline factors associated with achieving remission: sustained (SR), intermittent (IR) or never (NR) over a 5-year period in patients with early IP. Methods: Clinical and demographic data of patients with IP recruited to the Norfolk Arthritis Register (NOAR) were obtained at baseline and years 1, 2, 3 and 5. Remission was defined as no tender or swollen joints (out of 51). Patients were classified as NR or PR, respectively, if they were in remission at: no assessment or ⩾3 consecutive assessments after baseline, and IR otherwise. Ordinal regression and a random effects model, respectively, were used to examine the association between baseline factors, remission group and HAQ scores over time. Results: A total of 868 patients (66% female) were included. Of these, 54%, 34% and 12% achieved NR, IR and SR, respectively. In multivariate analysis, female sex (odds ratio, OR 0.47, 95% CI: 0.35, 0.63), higher tender joint count (OR = 0.94, 95% CI: 0.93, 0.96), higher HAQ (OR = 0.59, 95% CI: 0.48, 0.74), being obese (OR = 0.70, 95% CI: 0.50, 0.99), hypertensive (OR = 0.67, 95% CI: 0.50, 0.90) or depressed (OR = 0.74, 95% CI: 0.55, 1.00) at baseline were independent predictors of being in a lower remission group. IR and SR were associated with lower HAQ scores over time and lower DAS28 at year 5. Conclusion: Women with higher tender joint count and disability at baseline, depression, obesity and hypertension were less likely to achieve remission. This information could help when stratifying patients for more aggressive therapy
Phase Synchronization and Polarization Ordering of Globally-Coupled Oscillators
We introduce a prototype model for globally-coupled oscillators in which each
element is given an oscillation frequency and a preferential oscillation
direction (polarization), both randomly distributed. We found two collective
transitions: to phase synchronization and to polarization ordering. Introducing
a global-phase and a polarization order parameters, we show that the transition
to global-phase synchrony is found when the coupling overcomes a critical value
and that polarization order enhancement can not take place before global-phase
synchrony. We develop a self-consistent theory to determine both order
parameters in good agreement with numerical results
A Single-centre, Before-After Study of the Short- and Long-term Efficacy of Narivent® in the Treatment of Nasal Congestion
Objective:Nasal congestion is a common symptom in allergic and nonallergic rhinitis, rhinosinusitis and nasal polyposis. The present study evaluated the clinical effectiveness of Narivent®, an osmo..
Emergence of hierarchical networks and polysynchronous behaviour in simple adaptive systems
We describe the dynamics of a simple adaptive network. The network
architecture evolves to a number of disconnected components on which the
dynamics is characterized by the possibility of differently synchronized nodes
within the same network (polysynchronous states). These systems may have
implications for the evolutionary emergence of polysynchrony and hierarchical
networks in physical or biological systems modeled by adaptive networks.Comment: 4 pages, 4 figure
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