THE EFFECT OF THE THERMODYNAMIC MODELS ON THE THERMOECONOMIC RESULTS FOR COST ALLOCATION IN A GAS TURBINE COGENERATION SYSTEM

The thermoeconomics combines economics and thermodynamics to provide information not available from conventional energy and economic analysis. For thermoeconomics modeling one of the keys points is the thermodynamic model that should be adopted. Different thermodynamic models can be used in the modeling of a gas turbine system depending on the accuracy required. A detailed study of the performance of gas turbine would take into account many features. These would include the combustion process, the change of composition of working fluid during combustion, the effects of irreversibilities associated with friction and with pressure and temperature gradients and heat transfer between the gases and walls. Owing to these and others complexities, the accurate modeling of gas turbine normally involves computer simulation. To conduct elementary thermodynamic analyses, considerable simplifications are required. Thus, there are simplified models that lead to different results in thermoeconomics. At this point, three questions arise: How different can the results be? Are these simplifications reasonable? Is it worth using such a complex model? In order to answer these questions, this paper compares three thermodynamic models in a gas turbine cogeneration system from thermoeconomic point of view: cold air-standard model, CGAM model and complete combustion with excess air

Hierarchical Set Decision Diagrams and Regular Models

This paper presents algorithms and data structures that exploit a compositional and hierarchical specification to enable more efficient symbolic model-checking. We encode the state space and transition relation using hierarchical Set Decision Diagrams (SDD) [9]. In SDD, arcs of the structure are labeled with sets, themselves stored as SDD. To exploit the hierarchy of SDD, a structured model representation is needed. We thus introduce a formalism integrating a simple notion of type and instance. Complex composite behaviors are obtained using a synchronization mechanism borrowed from process calculi. Using this relatively general framework, we investigate how to capture similarities in regular and concurrent models. Experimental results are presented, showing that this approach can outperform in time and memory previous work in this area

Submucosal Tunnel Endoscopic Resection of Gastric Lesion Before Obesity Surgery: a Case Series

Background: Submucosal tumors (SMTs) of the gastrointestinal tract are a rare pathological entity comprising a wide variety of neoplastic and non-neoplastic lesions. Even if most SMTs are benign tumors (e.g., leiomyomas), a smaller portion may have a malignant potential (e.g., gastrointestinal stromal tumor (GIST)). Preoperative diagnosis of SMT in bariatric patients may arise challenging clinical dilemmas. Long-term surveillance may be difficult after bariatric surgery. Moreover, according to SMT location, its presence may interfere with planned surgery. Submucosal tunneling endoscopic resection (STER) has emerged as an effective approach for minimally invasive en bloc excision of SMTs. This is the first case series of STER for SMTs before bariatric surgery. Methods: Seven female patients underwent STER for removal of SMTs before bariatric surgery. All lesions were incidentally diagnosed at preoperative endoscopy. STER procedural steps comprised mucosal incision, submucosal tunneling, lesion enucleation, and closure of mucosal defect. Results: En bloc removal of SMT was achieved in all cases. Mean procedural time was of 45 min (SD 18.6). No adverse event occurred. Mean size of the lesions was 20.6 mm (SD 5.8). Histological diagnoses were 5 leyomiomas, 1 lipoma, and 1 low grade GIST. Bariatric procedure was performed after a mean period of 4.1 months (SD 1.6) from endoscopic resection. Conclusion: STER is a safe and effective treatment for the management of SMT even in bariatric patients awaiting surgery. Preoperative endoscopic resection of SMTs has the advantages of reducing the need for surveillance and removing lesions that could interfere with planned surgery. STER did not altered accomplishment of bariatric procedures

Efficient CSL Model Checking Using Stratification

For continuous-time Markov chains, the model-checking problem with respect to continuous-time stochastic logic (CSL) has been introduced and shown to be decidable by Aziz, Sanwal, Singhal and Brayton in 1996. Their proof can be turned into an approximation algorithm with worse than exponential complexity. In 2000, Baier, Haverkort, Hermanns and Katoen presented an efficient polynomial-time approximation algorithm for the sublogic in which only binary until is allowed. In this paper, we propose such an efficient polynomial-time approximation algorithm for full CSL. The key to our method is the notion of stratified CTMCs with respect to the CSL property to be checked. On a stratified CTMC, the probability to satisfy a CSL path formula can be approximated by a transient analysis in polynomial time (using uniformization). We present a measure-preserving, linear-time and -space transformation of any CTMC into an equivalent, stratified one. This makes the present work the centerpiece of a broadly applicable full CSL model checker. Recently, the decision algorithm by Aziz et al. was shown to work only for stratified CTMCs. As an additional contribution, our measure-preserving transformation can be used to ensure the decidability for general CTMCs.Comment: 18 pages, preprint for LMCS. An extended abstract appeared in ICALP 201

Integrated Modelling Frameworks for Environmental Assessment and Decision Support

As argued in Chapter 1, modern management of environmental resources defines problems from a holistic and integrated perspective, thereby imposing strong requirements on Environmental Decision Support Systems (EDSSs) and Integrated Assessment Tools (IATs). These systems and tools tend to be increasingly complex in terms of software architecture and computational power in order to cope with the type of problems they must solve. For instance, the discipline of Integrated Assessment (IA) needs tools that arc able to span a wide range of disciplines, from socio-economics to ecology to hydrology. Such tools must support a wide range of methodologies and techniques like agent-based modeling, Bayesian decision networks, optimization, multicriteria analyses and visualization tools, to name a few

Endoscopic internal drainage for the management of leak, fistula, and collection after sleeve gastrectomy: our experience in 617 consecutive patients

Background: Endoscopy plays a pivotal role in the management of adverse events (AE) following bariatric surgery. Leaks, fistulae, and post-operative collection after sleeve gastrectomy (SG) may occur in up to 10% of cases. Objectives: To evaluate the efficacy and safety of endoscopic internal drainage (EID) for the management of leak, fistula, and collection following SG. Setting: Retrospective, observational, single center study on patients referred from several bariatric surgery departments to an endoscopic referral center. Methods: EID was used as first-line treatment for the management of leaks, fistulae, and collections. Leaks and fistulae were treated with double pigtail stent (DPS) deployment in order to guarantee internal drainage and second intention cavity obliteration. Collections were treated with endoscropic ultrasound (EUS)–guided deployment of DPS or lumen apposing metal stents. Results: A total of 617 patients (83.3% female; mean age, 43.1 yr) were enrolled in the study for leak (n = 300, 48.6%), fistula (n = 285, 46.2%), and collection (n = 32, 5.2%). Median follow-up was 19.5 months. Overall clinical success was 84.7% whereas 15.3% of cases required revisional surgery after EID failure. Clinical success according to type of AE was 89.5%, 78.5%, and 90% for leak, fistula, and collection, respectively. A total of 10 of 547 (1.8%) presented a recurrence during follow-up. A total of 28 (4.5%) AE related to the endoscopic treatment occurred. At univariate logistic regression predictors of failure were: fistula (OR 2.012), combined endoscopic approach (OR 2.319), need for emergency surgery (OR 1.755), and previous endoscopic treatment (OR 4.818). Conclusion: Early EID for the management of leak, fistula, and post-operative collection after SG seems a safe and effective first-line approach with good long-term results

On the vanishing electron-mass limit in plasma hydrodynamics in unbounded media

We consider the zero-electron-mass limit for the Navier-Stokes-Poisson system in unbounded spatial domains. Assuming smallness of the viscosity coefficient and ill-prepared initial data, we show that the asymptotic limit is represented by the incompressible Navier-Stokes system, with a Brinkman damping, in the case when viscosity is proportional to the electron-mass, and by the incompressible Euler system provided the viscosity is dominated by the electron mass. The proof is based on the RAGE theorem and dispersive estimates for acoustic waves, and on the concept of suitable weak solutions for the compressible Navier-Stokes system

The role of tibialis posterior fatigue on foot kinematics during walking

<p>Abstract</p> <p>Background</p> <p>The purpose of this study was to investigate the effect of localised tibialis posterior muscle fatigue on foot kinematics during walking. It was hypothesised that following fatigue, subjects would demonstrate greater forefoot and rearfoot motion during walking. It was also postulated that the magnitude of the change in rearfoot motion would be associated with standing anatomical rearfoot posture.</p> <p>Methods</p> <p>Twenty-nine subjects underwent an exercise fatigue protocol aimed at reducing the force output of tibialis posterior. An eight camera motion analysis system was used to evaluate 3D foot kinematics during treadmill walking both pre- and post-fatigue. The anatomical rearfoot angle was measured during standing prior to the fatigue protocol using a goniometer.</p> <p>Results</p> <p>Peak rearfoot eversion remained unchanged following the fatigue protocol. Although increases in rearfoot eversion excursion were observed following fatigue, these changes were of a magnitude of questionable clinical significance (<1.0°). The magnitude of the change in rearfoot eversion due to fatigue was not associated with the anatomical measurement of standing rearfoot angle. No substantial changes in forefoot kinematics were observed following the fatigue protocol.</p> <p>Conclusions</p> <p>These data indicate that reduced force output of the tibialis posterior muscle did not alter rearfoot and forefoot motion during gait. The anatomical structure of the rearfoot was not associated with the dependence of muscular activity that an individual requires to maintain normal rearfoot kinematics during gait.</p