A stochastic optimization approach for paper recycling reverse logistics network design under uncertainty

One of the most important objectives of a manufacturing firm is the efficient design and operation of its supply chain to maximize profit. Paper is an example of a valuable material that can be recycled and recovered. Uncertainty is one of the characteristics of the real world. The methods that cope with uncertainty help researchers get realistic results. In this study, a two-stage stochastic programing model is proposed to determine a long term strategy including optimal facility locations and optimal flow amounts for large scale reverse supply chain network design problem under uncertainty. This network design problem includes optimal recycling and collection center locations and optimal flow amounts between the nodes in the multi-facility environment. Proposed model is suitable for recycling/manufacturing type of systems in reverse supply chain. All deterministic, stochastic models are mixed-integer programing models and are solved by commercial software GAMS 21.6/CPLEX 9.0

A stochastic optimization approach for paper recycling reverse logistics network design under uncertainty

One of the most important objectives of a manufacturing firm is the efficient design and operation of its supply chain to maximize profit. Paper is an example of a valuable material that can be recycled and recovered. Uncertainty is one of the characteristics of the real world. The methods that cope with uncertainty help researchers get realistic results. In this study, a two-stage stochastic programing model is proposed to determine a long term strategy including optimal facility locations and optimal flow amounts for large scale reverse supply chain network design problem under uncertainty. This network design problem includes optimal recycling and collection center locations and optimal flow amounts between the nodes in the multi-facility environment. Proposed model is suitable for recycling/manufacturing type of systems in reverse supply chain. All deterministic, stochastic models are mixed-integer programing models and are solved by commercial software GAMS 21.6/CPLEX 9.0

A heterogeneous fleet vehicle routing model for solving the LPG distribution problem: A case study

Vehicle Routing Problem (VRP) is an important management problem in the field of distribution and logistics. In VRPs, routes from a distribution point to geographically distributed points are designed with minimum cost and considering customer demands. All points should be visited only once and by one vehicle in one route. Total demand in one route should not exceed the capacity of the vehicle that assigned to that route. VRPs are varied due to real life constraints related to vehicle types, number of depots, transportation conditions and time periods, etc. Heterogeneous fleet vehicle routing problem is a kind of VRP that vehicles have different capacity and costs. There are two types of vehicles in our problem. In this study, it is used the real world data and obtained from a company that operates in LPG sector in Turkey. An optimization model is established for planning daily routes and assigned vehicles. The model is solved by GAMS and optimal solution is found in a reasonable time

P1385 Mechanical dispersion of the right atrium in dilated cardiomyopathy: does the etiology matter?

Abstract Funding Acknowledgements This work was supported by CREDO Project - ID: 49182, financed through the SOP IEC -A2-0.2.2.1-2013-1 cofinanced by the ERDF Background Mechanical dispersion assessed by myocardial strain reflects a susceptibility for arrhythmia development. While the contractile heterogeneity of both ventricles has been assessed in different clinical settings, the incidence and significance of right atrial (RA) dyssynchrony in dilated cardiomyopathy (DCM) are unknown. Methods 50 consecutive patients with DCM were divided in 2 groups according to the etiology: group I had 26 patients with ischemic DCM (68 ± 10 years, 23 men), group N had 24 patients with non-ischemic DCM (52 ± 12 years, 18 men). We assessed the RA strain by 2D speckle-tracking analysis, and we calculated RA mechanical dispersion as the standard deviation of the time-to-peak contraction strain in 6 RA segments. 20 healthy individuals served as controls. Data were compared between groups with one-way analysis of variance and using a post-hoc Bonferroni correction. Results The RA strain was reduced in DCM patients, both in group I and in group N. All three components of the RA strain were most reduced in group I (p &amp;lt; 0.001 for reservoir and conduit strain, p = 0.001 for contraction strain) (Table). The RA mechanical dispersion was highest in group I (56.8 ± 21.6 ms), followed by group N (39.9 ± 15.3 ms) and controls (23.8 ± 7.7 ms)(p &amp;lt; 0.001). Patients with DCM and documented supraventricular arrhythmias (either atrial fibrillation, atrial flutter or premature atrial contractions) had higher RA mechanical dispersion (57.5 ± 19.7 ms) than DCM patients with no documented atrial rhythm disturbances (44.9 ± 19.9 ms, p = 0.04). Conclusion Mechanical dispersion of the RA is pronounced in patients with DCM and it is higher in patients with documented supraventricular arrhythmias. Patients with ischemic DCM have a more pronounced mechanical dispersion of the RA than patients with non-ischemic DCM, reflecting a more heterogenous RA contraction in ischemic heart disease when compared to other forms of DCM. The prognostic significance of RA dyssynchrony in a disease primarily involving the left heart warrants further studies. Group I Group N Controls P value Reservoir RA strain (%) 12.9 ± 7.4§ 17.6 ± 12.9§ 30.1 ± 9.9 &amp;lt;0.001 Conduit RA strain (%) -6 ± 5.5§ -8 ± 8.9§ -15.2 ± 6.4 &amp;lt;0.001 Contraction RA strain (%) 6.9 ± 6§ 9.6 ± 8.1 14.9 ± 6.1 0.001 RA mechanical dispersion (ms) 56.8 ± 21.6§ 39.±15.3§* 23.8 ± 7.7 &amp;lt;0.001 § significant difference with controls; * significant difference with group I </jats:sec

Potential savings in buildings using stand-alone PV systems

This research analyses the electricity consumption and CO2 emissions of 3 hotels in Greece using energy auditing. Following this analysis, the energy generation, at the same month, from a stand alone PV system will be presented for each case, showing its contribution in electricity consumption and its possible share on the total electricity consumption. The PV systems are installed from the same company, and they have different power capacity of 75, 100 and 200kW. This research aims at showing potential energy and emissions savings from the selected cases, showing the necessity to promote the application of renewable energy sources and in particular PV stand alone systems in Greek hotels considering the current socio-economic situation of the country. © Springer-Verlag Berlin Heidelberg 2013

P907 Ventriculo-vascular interaction in patients with severe aortic stenosis: a comparison of three different clinical settings

Abstract Funding Acknowledgements This work was supported by CREDO Project - ID: 49182, financed through the SOP IEC -A2-0.2.2.1-2013-1 cofinanced by the ERDF Ventriculo-arterial coupling (VAC) reflects the interaction between the ventricle and the arterial system and its prognostic role was studied in different clinical settings. VAC can be assessed with echocardiography as the ratio between the arterial elastance (Ea) and the end-systolic left ventricular elastance (EES). Data concerning the role of VAC in severe aortic stenosis (AS) are scarce. We aimed to determine VAC in patients (pts) with severe AS and assess its relationship with symptoms. We included 61 consecutive pts with severe AS (vave area &amp;lt; 1 cm2) and we divided them in 3 groups according to their symptoms: group A consisted of 28 pts (81 ± 10 yrs, 14 men) admitted for acute pulmonary edema, group B consisted of 25 pts (76 ± 12 yrs, 13 men) with either angina, syncope or dyspnea class I-III NYHA and group C consisted of 8 asymptomatic patients (71 ± 19 yrs, 3 men). We determined the VAC non-invasively and we compared the results between the 3 groups using one-way analysis of variance and a post-hoc Tukey test. There were no significant differences in age (p = 0.08) and aortic valve area (p = 0.18) between groups. Variations of Ea and EES between groups were not significant (p = 0.08 and p = 0.94, respectively). However, VAC differed significantly between the 3 groups, being most impaired in group A (1.11 ± 0.69), followed by 0.77 ± 0.23 in group B and 0.73 ± 0.16 in group C (p = 0.03). The left ventricular ejection fraction (EF) also differed significantly between groups: 41 ± 13% in group A, 51 ± 11% in group B and 57 ± 3% in group C (p &amp;lt; 0.001). VAC and the EF had a moderate negative correlation in group A (r=-0.52, p = 0.004) and group B (r=-0.51, p = 0.009), but no correlation in group C (p = 0.37). VAC is impaired in patients with severe AS and acute heart failure and it differs significantly from VAC in severe AS with chronic, stable symptoms and from VAC in asymptomatic severe AS. This suggests that the progression of symptoms in severe AS might be related to the interactions between the left ventricle and the vascular load, making thus VAC a potential therapeutic target and a parameter to be considered in the thorough evaluation of patients with severe AS. Group A Group B Group C Ea 2.69 ± 1.31 2.09 ± 0.94 1.95 ± 0.60 p = 0.08 EES 2.93 ± 1.90 2.87 ± 1.33 2.71 ± 0.73 p = 0.94 VAC 1.11 ± 0.69 0.77 ± 0.23* 0.73 ± 0.16* p = 0.03 EF 41 ± 13% 51 ± 11%* 57 ± 3%* p &amp;lt; 0.001 *significant difference with group A </jats:sec

P2598Left atrial mechanics in patients with acute pulmonary edema and preserved ejection fraction

Abstract Background The left atrium (LA) is a highly dynamic chamber that has 3 mechanical functions (reservoir, conduit, booster pump), as well as additional endocrine and regulatory properties. It is a marker of both the severity and chronicity of diastolic dysfunction and its remodelling has been shown to be a reliable predictor of clinical outcome in patients with heart disease. While LA function has been extensively studied in chronic heart failure, information about LA mechanics in patients with acute heart failure and preserved left ventricular ejection fraction (EF) are scarce. Purpose We sought to assess LA mechanics in a cohort of patients with acute pulmonary edema and preserved EF and compare it with a normal reference group. Methods We included 50 consecutive patients (22 men) with acute pulmonary edema, preserved EF and sinus rhythm in our study. Patients with significant mitral or aortic valve disease were not considered eligible. The control group consisted of 30 subjects (18 men) with no previous cardiovascular disease. We performed conventional transthoracic echocardiography for all patients and we assessed various parameters of LA mechanics. To evaluate the reservoir function, we determined the total ejection volume (EV), the total EF, the LA expansion index (LAEI) and the LA function index (LAFI). To evaluate the conduit function, we determined the passive EV and passive EF. For the booster pump function, we determined the active EV, active EF, the atrial filling fraction, the ejection force and the LA kinetic energy (LAKE). We used T-test to compare the parameters between the two groups. Results The mean age in the study group was 72±14 years, while in the control group the mean age was 56±16 years (p=0.06). The total EV did not differ significantly between groups (p=0.44). The total LA ejection fraction was lower in the study group: 29±10% vs. 51±9% (p&lt;0.001), as well as the LAEI (45.1±24.6 vs. 110.9±32.1, p&lt;0.001) and the LAFI (0.17±0.12 vs. 0.58±0.20, p&lt;0.001). Among parameters assessing LA conduit function, there were no differences in passive EV (p=0.64), but passive LA ejection fraction was significantly lower in the study group: 15±7% vs. 28±11%, p=0.003. The same trend was noted for active LA ejection fraction (16±10% vs. 31±13%, p=0.005). The ejection force was impaired in the study group: 39.1±30.6 kdynes vs. 15.2±12.3 kdynes, p&lt;0.001. Other parameters evaluating LA booster pump function did not differ significantly between groups (p=0.12 for atrial filling fraction, p=0.74 for LAKE). Conclusion All three integrated phases of left atrial mechanics (reservoir, conduit, booster pump) are impaired in patients with acute pulmonary edema and preserved left ventricular EF. These findings highlight the importance of diastolic dysfunction in the pathogenesis of acute heart failure for these patients and they suggest that LA dysfunction might be a potential therapeutic target in this clinical setting. Acknowledgement/Funding This work was supported by CREDO Project - ID: 49182, financed through the SOP IEC-A2-0.2.2.1-2013-1 cofinanced by the ERDF </jats:sec

Non-invasive assessment of right ventriculo-arterial coupling in dilated cardiomyopathy – insights from 3D echocardiography

Abstract Background Right ventricular-pulmonary artery coupling (RVPAC) reflects the mechanical efficiency of the interaction between the right ventricle (RV) and the pulmonary circulation unit. Although it has been traditionally assessed with right heart catheterisation (RHC), modern imaging techniques enable the non-invasive estimation of the RVPAC, which proved to correlate well with measurements derived from RHC. Methods We used three-dimensional (3D) echocardiography to study 88 consecutive patients (60.4±13.4 years, 69 men) with dilated cardiomyopathy (DCM) and left ventricular ejection fraction&amp;lt;40% and we measured the RV volumes and RV ejection fraction (RVEF) using dedicated software. 15 healthy individuals served as controls. RVPAC was estimated non-invasively as the ratio between the RV end-systolic volume and stroke volume. Right-sided heart failure was defined as either elevated jugular venous pressure, pedal oedema or congestive hepatomegaly. Results Patients with DCM showed larger RV end-diastolic volume (163±60.9 ml vs. 91.3±13.2 ml; p&amp;lt;0.0001), as well as larger RV end-systolic volume (97.3±43.2 ml vs. 39.8±7.2 ml; p&amp;lt;0.0001) than healthy controls. The patients in the study group showed lower RVEF: 41.5±8.5% vs. 56.5±3.6% (p&amp;lt;0.0001). Non-invasive RVPAC was 1.53±0.60 in DCM patients vs. 0.78±0.11 in controls (p&amp;lt;0.0001). RVPAC had an excellent negative correlation with RVEF, both in DCM patients (r=−0.96, p&amp;lt;0.0001) and in controls (r=−0.99, p&amp;lt;0.0001). Patients with no signs of right-sided heart failure had lower RVPAC (1.38±0.45) than patients with at least one sign of right heart failure (1.90±0.72, p=0.03). Patients with mild symptoms of heart failure (NYHA classes 1 or 2) showed lower RVPAC (1.37±0.48) than DCM patients with severe heart failure (NYHA classes 3 or 4): 1.79±0.68 (p=0.003). Conclusions 3D echocardiography provides useful insights in the functional assessment of the cardiopulmonary unit. Non-invasive RVPAC is impaired in patients with DCM, and it is more impaired when signs of right-sided heart failure are present. Severe symptoms are associated with more pronounced decoupling of the RV and the pulmonary circulation. The prognostic significance of non-invasive RVPAC in a disease primarily involving the left ventricle remains to be clarified. Funding Acknowledgement Type of funding source: Other. Main funding source(s): This work was supported by CREDO Project - ID: 49182, financed through the SOP IEC -A2-0.2.2.1-2013-1 cofinanced by the ERDF </jats:sec