A generic persistence model for CLP systems (and two useful implementations)

This paper describes a model of persistence in (C)LP languages and two different and practically very useful ways to implement this model in current systems. The fundamental idea is that persistence is a characteristic of certain dynamic predicates (Le., those which encapsulate state). The main effect of declaring a predicate persistent is that the dynamic changes made to such predicates persist from one execution to the next one. After proposing a syntax for declaring persistent predicates, a simple, file-based implementation of the concept is presented and some examples shown. An additional implementation is presented which stores persistent predicates in an external datábase. The abstraction of the concept of persistence from its implementation allows developing applications which can store their persistent predicates alternatively in files or databases with only a few simple changes to a declaration stating the location and modality used for persistent storage. The paper presents the model, the implementation approach in both the cases of using files and relational databases, a number of optimizations of the process (using information obtained from static global analysis and goal clustering), and performance results from an implementation of these ideas

Multi-state techno-economic model for optimal dispatch of grid connected hydrogen electrolysis systems operating under dynamic conditions

The production of hydrogen through water electrolysis is a promising pathway to decarbonize the energy sector. This paper presents a techno-economic model of electrolysis plants based on multiple states of operation: production, hot standby and idle. The model enables the calculation of the optimal hourly dispatch of electrolyzers to produce hydrogen for different end uses. This model has been tested with real data from an existing installation and compared with a simpler electrolyzer model that is based on two states. The results indicate that an operational strategy that considers the multi-state model leads to a decrease in final hydrogen production costs. These reduced costs will benefit businesses, especially while electrolysis plants grow in size to accommodate further increases in demand

Elastography of the thyroid

AbstractThyroid nodules are very common, while thyroid cancer is rare and has a very good prognosis. Thyroid nodule ultrasound characterization performed by experienced clinicians allows the selection of the tumours to be punctured and guiding fine needle aspiration (FNA). FNA provide cytology information able to differentiate benign tumours from cancer in approximately 80% of cases. However, it remains difficult to identify thyroid cancers with ultrasound imaging, as demonstrated by the very low rate of cancers detected in all of the carried out FNA (approximately 5%). As a majority of thyroid cancers are hard, the stiffness evaluation has become part of nodular characterization. Since 2005, elastography has been used for the evaluation of thyroid nodules; quasi-static elastography was the first technique available and used, at first, an external pressure induced by the probe, which was then replaced by carotid internal excitation allowing improvement in sensitivity. Semi-quantitative analysis allows comparison of tissue elasticities between tissue with elasticity anomalies and normal tissue and provides therefore useful analytic information. Shear wave elastography (SWE) provides a map of the elasticity in a region and allows stiffness quantification of lesions in kilopascals in order to reinforce the predictive value of malignancy. A tumour whose stiffness is greater than 65kPa or for which the stiffness ratio is greater than 3.7 compared to surrounding healthy tissue is highly suspicious. SWE may enable the detection of malignant follicular tumours that currently escape detection by the ultrasound-guided ultrasound/aspiration cytology couple. Lymph node metastasis of papillary thyroid cancer can also be detected by elastography due to its increased stiffness