A feasibility analysis of waste heat recovery systems for marine applications

The shipping sector is today facing challenges which require a larger focus on energy efficiency and fuel consumption. In this article, a methodology for performing a feasibility analysis of the installation of a WHR (waste heat recovery) system on a vessel is described and applied to a case study vessel. The method proposes to calculate the amount of energy and exergy available for the WHR systems and to compare it with the propulsion and auxiliary power needs based on available data for ship operational profile. The expected exergy efficiency of the WHR system is used as an independent variable, thus allowing estimating the expected fuel savings when a detailed design of the WHR system is not yet available. The use of the proposed method can guide in the choice of the installation depending on the requirements of the owner in terms of payback time and capital investment. The results of the application of this method to the case study ship suggest that fuel savings of 5%–15% can realistically be expected, depending on the sources of waste heat used and on the expected efficiency of the WHR system

Development of a combined mean value-zero dimensional model and application for a large marine four-stroke diesel engine simulation

In this article, a combined mean value–zero dimensional model is developed using a modular approach in the computational environment of Matlab/Simulink. According to that, only the closed cycle of one engine cylinder is modelled by following the zero-dimensional approach, whereas the cylinder open cycle as well as the other engine components are modelled according to the mean value concept. The proposed model combines the advantages of the mean value and zero-dimensional models allowing for the calculation of engine performance parameters including the in-cylinder ones in relatively short execution time and therefore, it can be used in cases where the mean value model exceeds its limitations. A large marine four-stroke Diesel engine steady state operation at constant speed was simulated and the results were validated against the engine shop trials data. The model provided results comparable to the respective ones obtained by using a mean value model. Then, a number of simulation runs were performed, so that the mapping of the brake specific fuel consumption for the whole operating envelope was derived. In addition, runs with varying turbocharger turbine geometric area were carried out and the influence of variable turbine geometry on the engine performance was evaluated. Finally, the developed model was used to investigated the propulsion system behaviour of a handymax size product carrier for constant and variable engine speed operation. The results are presented and discussed enlightening the most efficient strategies for the ship operation and quantifying the expected fuel savings

The application of process integration to the optimisation of cruise ship energy systems: a case study

In recent years, the shipping industry has faced an increasing number of challenges in terms of fluctuating fuel prices, stricter environmental regulations, and concerns about global warming. In this situation, passenger volumes on cruise ships have increased from around 4 million to 13 million from 1990 to 2008 and keep growing today. A small cruise ship can emit about 85 tons of CO2 per day, and require around 27 tons of fuel per day. To keep up with market demand, while reducing their impact on the environment, cruise ships will need to improve their energy efficiency. Most previous research in marine technology relates to energy efficiency focused on propulsion, which for most ship types constitutes the largest energy demand. On cruise ships, however, auxiliary heat and electric power also have a significant importance. For this reason, we focus in this paper on the heat demand and its integration with available sources of waste heat on board. In this study, the principles of process integration are applied to the energy system of a cruise ship operating in the Baltic Sea. The heat sources (waste heat from the main and auxiliary engines in form of exhaust gas, cylinder cooling, charge air cooling, and lubricating oil cooling) and sinks (HVAC, hot water, fuel heating) are evaluated based on one year of operational data and used to generate four operating conditions that best represent ship operations. Applying the pinch analysis to the system revealed that the theoretical potential for heat integration on board could potentially allow the reduction of the external heat demand by between 35% and 85% depending on the investigated case. A technoeconomic optimisation allowed the identification of the most economically viable heat exchanger network designs: two in the “retrofit” scenario and one in the “design” scenario, with a reduction of 13-33%, 15-27% and 46-56% of the external heat demand, respectively. Given the high amount of heat being available after the process integration, we also analysed the potential for the installation of a steam turbine for the recovery of the energy available in the exhaust gas, which resulted in up to 900 kW of power being available for on board electric power demand

ODes aCCSES Report: Optimal design and control of cruise ship energy systems

Reducing global emissions of greenhouse gases while promoting social and economicdevelopment is one of the toughest challenges ever faced in the history of human kind.This challenge is affecting all sectors of human activities: process plants, land-basedtransportation, residential buildings. In this framework, the maritime industry faces no smaller challenge. Sea trade and the cruise industry keep growing despite economic crises,while CO2 emissions from shipping need to fall, as for any other sectors, need to fall.This report, main deliverable of the ODes aCCES project (Optimal Design and Control of Cruise ship Energy Systems) is meant to provide the interested reader with relevant information to be used in the process of optimizing the design of ship energy systems,and particularly those of cruise ships. The report presents a broad review of different optimization strategies and methods; of methods specifically developed for the optimization of energy systems; and of the application of such methods to the optimization of ship energy system

The large-scale environment of FR 0 radio galaxies

We explore the properties of the large-scale environment of FR0 radio galaxies belonging to the FR0CAT sample which includes 104 compact radio sources associated with nearby (z<0.05) early-type galaxies. By using various estimators we find that FR0s live in regions of higher than the average galaxies density and a factor two lower density, on average, with respect to FRI radio galaxies. This latter difference is driven by the large fraction (63%) of FR0s located in groups formed by less than 15 galaxies, an environment which FRIs rarely (17%) inhabit. Beside the lack of substantial extended radio emission defining the FR0s class, this is the first significant difference between the properties of these two populations of low power radio galaxies. We interpret the differences in environment between FR0s and FRIs as the due to an evolutionary link between local galaxies density, BH spin, jet power, and extended radio emission.Comment: 11 pages, 6 figures, 3 tables (Pre-proofs version - Published in A&A

Low-power Secret-key Agreement over OFDM

Information-theoretic secret-key agreement is perhaps the most practically feasible mechanism that provides unconditional security at the physical layer to date. In this paper, we consider the problem of secret-key agreement by sharing randomness at low power over an orthogonal frequency division multiplexing (OFDM) link, in the presence of an eavesdropper. The low power assumption greatly simplifies the design of the randomness sharing scheme, even in a fading channel scenario. We assess the performance of the proposed system in terms of secrecy key rate and show that a practical approach to key sharing is obtained by using low-density parity check (LDPC) codes for information reconciliation. Numerical results confirm the merits of the proposed approach as a feasible and practical solution. Moreover, the outage formulation allows to implement secret-key agreement even when only statistical knowledge of the eavesdropper channel is available.Comment: 9 pages, 4 figures; this is the authors prepared version of the paper with the same name accepted for HotWiSec 2013, the Second ACM Workshop on Hot Topics on Wireless Network Security and Privacy, Budapest, Hungary 17-19 April 201

Plasminogen activation system in goat milk and its relation with composition and coagulation properties.

The activity of plasmin (PL), plasminogen (PG), and plasminogen activator (PA) and their correlation with goat milk components and milk clotting parameters were investigated. Seven late-lactating Saanen goats were used to provide milk samples that were analyzed for PL, PG, and PA activity (colorimetric assay) fat, protein, noncasein nitrogen, nonprotein nitrogen, casein content, and somatic cell count (SCC). Milk clotting parameters (rennet coagulating time = coagulation time; K20 = firming rate of curd; A30 = curd firmness) were measured with a formagraph. Average milk yield and composition were similar to those previously observed in other studies. Plasmin, PG, and PA activity, expressed as units/ml, were, respectively, 20.04 +/- 0.94, 3.21 +/- 0.04, and 1154 +/- 57.61. Plasminogen activity was surprisingly low compared with other species (bovine, ovine), but it was consistent with the high activity of PA. A negative significant correlation was observed between PL and milk casein content. The correlation coefficients between PL and casein/protein ratio and PA and casein/protein ratio were negative and significant. A positive significant correlation was observed between PL and rennet clotting time and PA and rennet clotting time. Also positive was the correlation between PL and K20 and PA and K20. The plasmin activity was negatively correlated with A30. High plasmin and plasminogen activator activity in goat milk appeared to be negatively related with coagulating properties in late lactation, most probably via degradation of casein due to plasmin activity

Pure Variable Inclusion Logics

The aim of this article is to discuss pure variable inclusion logics, that is, logical systems where valid entailments require that the propositional variables occurring in the conclusion are included among those appearing in the premises, or vice versa. We study the subsystems of Classical Logic satisfying these requirements and assess the extent to which it is possible to characterise them by means of a single logical matrix. In addition, we semantically describe both of these companions to Classical Logic in terms of appropriate matrix bundles and as semilattice-based logics, showing that the notion of consequence in these logics can be interpreted in terms of truth (or non-falsity) and meaningfulness (or meaninglessness) preservation. Finally, we use Płonka sums of matrices to investigate the pure variable inclusion companions of an arbitrary finitary logic.Fil: Paoli, Francesco. Università Degli Studi Di Cagliari.; ItaliaFil: Pra Baldi, Michele. Università Degli Studi Di Cagliari.; ItaliaFil: Szmuc, Damián Enrique. Universidad de Buenos Aires. Facultad de Filosofía y Letras; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Parque Centenario. Instituto de Investigaciones Filosóficas. - Sociedad Argentina de Análisis Filosófico. Instituto de Investigaciones Filosóficas; Argentin

Admission of foreign citizens to the general teaching hospital of Bologna, northeastern Italy: an epidemiological and clinical survey.

BACKGROUND: The emergency regarding recent immigration waves into Italy makes continued healthcare monitoring of these populations necessary. METHODS: Through a survey of hospital admissions carried out during the last five years at the S. Orsola-Malpighi General Hospital of Bologna (Italy), all causes of admission of these subjects were evaluated, together with their correlates. Subsequently, we focused on admissions due to infectious diseases. All available data regarding foreign citizens admitted as inpatients or in Day-Hospital settings of our teaching hospital from January 1, 1999, to March 31, 2004, were assessed. Diagnosis-related group (DRG) features, and single discharge diagnoses, were also evaluated, and a further assessment of infectious diseases was subsequently made. RESULTS: Within a comprehensive pool of 339,051 hospitalized patients, foreign citizen discharges numbered 7,312 (2.15%), including 2,542 males (34.8%) and 4,769 females (65.2%). Males had a mean age of 36.8±14.7 years, while females were aged 30.8±12.2 years. In the assessment of the areas of origin, 34.6% of hospitalizations were attributed to patients coming from Eastern Europe, 15.3% from Northern Africa, 7.3% (comprehensively) from Western Europe and United States, 6.9% from the Indian subcontinent, 5.9% from sub-Saharan Africa, 5.7% from Latin America, 4.1% from China, 2.5% from the Philippines, and 1.1% from the Middle East. Among women, most hospitalizations (58.8%) were due to obstetrical-gynecological procedures or diseases, including assistance with delivery (27.1%), and pregnancy complications (18.7%), followed by psycho-social disturbances (5.9%), malignancies (5.1%), gastrointestinal diseases (4.7%), and voluntary pregnancy interruption (4.4%). Among men, the most frequent causes of admissions were related to trauma (15.9%), followed by gastroenteric disorders (12%), heart-vascular diseases (8.9%), psycho-social disorders (8.4%), respiratory (7.1%), kidney (6.1%), liver (5.2%), and metabolic (4.9%) diseases, and alcohol or substance abuse (4.2%). Infectious diseases (alone or with concurrent disorders) were reported in 881 discharged individuals, representing 12.1% of the 7,312 DRGs attributed to foreign patients. The comprehensive patient population discharged from our hospital with at least one infectious disease diagnosis had lower rates of respiratory tract infections, followed by chronic viral hepatitis, HIV infection and related diseases, enterocolitis, pulmonary tuberculosis, pyelonephritis, severe skin and soft tissue infection, meningoencephalitis, and malaria, as the most frequently-reported disorders. CONCLUSIONS: Our survey, through a combined analysis of both DRGs and discharge diagnoses, allowed us to conclude that 12.1% of foreign citizens hospitalized at our General teaching Hospital of Bologna (Italy) suffered from at least one infectious disease. Respiratory tract, liver, and gastrointestinal infections, and HIV infection, were found with an appreciable frequency among discharge diagnoses, while the frequency of malaria and meningoencephalitis was lower, compared with other series. Among disorders other than infectious diseases, obstetric-gynecological conditions and post-traumatic episodes (for male patients) were the most frequent causes of hospitalization