An empirical study on the impact of static typing on software maintainability

Static type systems play an essential role in contemporary programming languages. Despite their importance, whether static type systems impact human software development capabilities remains open. One frequently mentioned argument in favor of static type systems is that they improve the maintainability of software systems—an often-used claim for which there is little empirical evidence. This paper describes an experiment that tests whether static type systems improve the maintainability of software systems, in terms of understanding undocumented code, fixing type errors, and fixing semantic errors. The results show rigorous empirical evidence that static types are indeed beneficial to these activities, except when fixing semantic errors. We further conduct an exploratory analysis of the data in order to understand possible reasons for the effect of type systems on the three kinds of tasks used in this experiment. From the exploratory analysis, we conclude that developers using a dynamic type system tend to look at different files more frequently when doing programming tasks—which is a potential reason for the observed differences in time.     

Building a geodatabase for mapping hydrogeological features and 3D modeling of groundwater systems: Application to the Saguenay-Lac-St.-Jean region, Canada

Understanding and managing groundwater resources require the integration of a large amount of high-quality data from a variety of sources. Due to the limitations in accessing information related to groundwater and subsurface conditions, the gathering of available existing information is of crucial importance when conducting a successful hydrogeological study. Here, we present an approach for the development of an exhaustive and comprehensive groundwater database through (1) the gathering of relevant sources of information relating to groundwater, and (2) the application of a quality control process in order to screen the data for accuracy and quality. This hydrogeological database is then implemented within a GIS (geographic information system) framework coupled to a Relational Database Management System (RDBMS) as a personal geodatabase (ESRI format) GIS technology. Once established, the spatial database allows a user to request the relevant data required for a specific hydrogeological study. In addition, stratigraphic data stored within the spatial database may be utilized for constructing 3D subsurface hydrostructural models. In order to achieve this objective, the software Arc Hydro Groundwater combined with the ArcGIS spatial database is shown to be appropriate for the 3D structural representation of aquifers (groundwater reservoirs). The innovative contribution of this approach in building 3D hydrostructural subsurface models from a spatial database resides in simplifying the required step-by-step processes by considering a unified compatible combination of “RDBMS-ArcGIS-Arc Hydro Groundwater” technologies. The proposed methodology is illustrated using data from an ongoing project aimed at developing an inventory of the groundwater resources of the Saguenay-Lac-Saint-Jean region, Quebec (Canada).     

Unconstrained keystroke dynamics authentication with shared secret

Among all the existing biometric modalities, authentication systems based on keystroke dynamics present interesting advantages. These solutions are well accepted by users and cheap as no additional sensor is required for authenticating the user before accessing to an application. In the last thirty years, many researchers have proposed, different algorithms aimed at increasing the performance of this approach. Their main drawback lies on the large number of data required for the enrollment step. As a consequence, the verification system is barely usable, because the enrollment is too restrictive. In this work, we propose a new method based on the Support Vector Machine (SVM) learning satisfying industrial conditions (i.e., few samples per user are needed during the enrollment phase to create its template). In this method, users are authenticated through the keystroke dynamics of a shared secret (chosen by the system administrator). We use the GREYC keystroke database that is composed of a large number of users (100) for validation purposes. We compared the proposed method with six methods from the literature (selected based on their ability to work with few enrollment samples). Experimental results show that, even though the computation time to build the template can be longer with our method (54 s against 3 s for most of the others), its performance outperforms the other methods in an industrial context (Equal Error Rate of 15.28% against 16.79% and 17.02% for the two best methods of the state-of-the-art, on our dataset and five samples to create the template, with a better computation time than the second best method).     

Contribution of plant-based sauces to the vitamin A intake of young children in Benin

A food consumption survey on 420 children was conducted in four areas in Benin to identify the local vitamin A (VA)-rich foods most frequently eaten and assess their contribution to the coverage of VA requirements of young children. Mangoes, eggs, red palm oil, various leafy vegetable (LV) sauces and palm nut juice sauce appeared to be the main VA-rich foods consumed. The recipes of the most promising sauces were characterised. Sauces with red palm oil/palm nut juice showed high carotenoid contents ranging from 0.9 ± 0.3 to 4.0 ± 0.8 mg Retinol Activity Equivalent/100 g dry matter (DM). Lipid contents were also high (from 39.6 to 66.8 g/100 g DM). When consumed, and taking into account the mean quantity eaten per meal, LV sauces containing red palm oil or palm nut juice contributed to the meeting of more than 70% of the recommended VA intake of young children.     

Reliability assessment on new reprogrammable non-volatile memory devices based on SiCr–O

The reliability of SiCr–O based reprogrammable non-volatile resistive memory devices is investigated. Superior data retention performances are confirmed with a lifetime of 10 k h at 245 °C. The activation energy is determined by experiments as 1.28 eV, projecting an intrinsic data retention lifetime of more than 100 years at 175 °C. An endurance life of a thousand program/erase cycles is achieved. The impact of dielectric in direct contact with the SiCr–O film, the layout of the device and the preconditioning step on endurance life are studied. Transmission electron microscopy cross-sections are made to understand the mechanism of the endurance failure. Electro-thermal simulations are performed to gain insight on the observed phenomena and to give directions for further improvements.     

Removal of total dissolved solids, nitrates and ammonium ions from drinking water using charge-barrier capacitive deionisation

A charge-barrier capacitive deionisation system was tested for electrochemical removal of Total Dissolved Solids (TDS), nitrates and ammonium ions. Several experiments were conducted with inorganic species spiked in tap water. The system efficiency was first evaluated using experimental statistical designs with different concentrations of NaCl (150 to 3000 mg/L). The raw water conductivity and the targeted residual TDS in treated water were the key process variables. Power consumption increased linearly as the difference between these two values increased. Water recovery rate and electrical consumption, which varied respectively from 63.9% to 95.8% and from 0.45 to 5.35 kWh/m³, were adequately described by a simple linear regression model (R²: 0.98 and 0.99, respectively). Additional experiments performed on nitrates (100 mg N-NO₃/L) and ammonium ions (1000 mg N-NH₄/L) showed high levels of removal. A rise in TDS concentration led to a decrease in their removal due to the competition for electrodes carbon adsorption sites. It was concluded from this study that this technology offers an innovative alternative for demineralising water. However, assays should be conducted in natural waters and in a steady-state manner to confirm data obtained and get long-term performance.     

Properties of geothermal fluids in Switzerland: A new interactive database

A database on geothermal fluids in Switzerland, called BDFGeotherm, has been compiled. It consists of nine related tables with fields describing the geographical, geological, hydrogeological and geothermal conditions of each sampling location. In all, 203 springs and boreholes from 82 geothermal sites in Switzerland and neighboring regions are listed in this new interactive Microsoft Access database. BDFGeotherm is a functional tool for various phases of a geothermal project such as exploration, production or fluid re-injection. Many types of queries can be run, using any fields from the database, and the results can be put into tables and printed or exported and saved in other files. In addition to describing the database structure, this paper also gives a summary of the reservoir formations, the geographical distribution of hydraulic parameters, the geochemical types of thermal waters and the potential geothermal resources associated with the sites.     

Combined temperature–time parameters during the pressing of curd as a tool to modulate the oiling-off of Swiss cheese

Oiling-off is essential for the culinary functional properties of hard- and semi-hard cheeses. However, the parameters implied in the mechanisms leading to oiling-off are not well known. In Emmental cheese, a marked change in the supramolecular organization of fat occurs during the pressing of the warm curd and could be related to the oiling-off of cheese. To check this hypothesis and to determine the relative effects of the temperature and pressing strength, twin-cheeses were submitted to various cooling rates after the curd have been dipped from the vat. These cheeses were either pressed or non-pressed. Using this strategy, we showed that a higher heat load yields to larger inclusions of fat in the cheese matrix, which has been characterised using confocal laser scanning microscopy, and to higher oiling-off. The heat load applied to the curd (integral of the temperature vs. time curve) and oiling-off of cheeses aged of 5 days were linearly related with r² = 0.89. In contrast, the pressing strength did not influence oiling-off. As a conclusion, the heat load applied during pressing and acidification could be a tool to modulate the oiling-off of Swiss cheese.     

An accurate HMM-based similarity measure between finite sets of histograms

Pattern Analysis and Applications - Histogram analysis has nowadays gain in interest, and a lot of work yet address this task. In most of the existing approaches, histograms are manipulated as...