DETERMINATION OF A SIMPLE AND ROBUST METHOD TO CALCULATE IGNITION DELAY IN COMPRESSION IGNITION ENGINES: APPLICATION TO DIESEL-BIODIESEL-ETHANOL BLENDS

Today, the automobile industry is under increasing pressure from governments and environmental organizations to lower their carbon footprint. Car manufacturers release new models that follow modern and severe norms of pollutant emissions using eco-friendly technologies. Their strategy follows two main pathways: decarbonization and increase of efficiency. In order to achieve the aforementioned objective, the replacement of fossil fuels with renewable biofuels with lower carbon footprints, such as biodiesel and/or ethanol, contribute to the decarbonization of current internal combustion engines. However, changes in the fuel composition also imply some adjustments in the injection and combustion settings to optimize the engine operation. An important parameter to assess the combustion process in a compression ignition (CI) engine is the ignition delay (ID), defined as the duration between the start of fuel injection (SOI) and the start of combustion (SOC). Different direct and indirect approaches are reported in the literature to measure or calculate the ID. This study investigates two indirect methods based on the measurement of the indicated pressure inside the combustion chamber, throughout the displacement of the piston. These measurements are based on the position of the maximum of the third-order derivative of pressure as a function of the crank angle and the subjective shift from a polytropic compression process, respectively. The objective of the present work is to define an objective criterion to quantify this shift in order to allow a unique determination of the ID, independently of the adopted method. Thus, data of six different fuel blends of diesel-biodiesel-ethanol in a four-stroke CI engine from tests performed at PUC Rio’s Vehicular Engineering Laboratory for different loads and engine speeds were analyzed using the software Matlab. As observed in previous literature, the results show that the addition of biodiesel and ethanol concentration in the blends slightly increases the ID. Moreover, the difference between the experimental pressure with combustion and the calculated pressure in the polytropic compression process at the SOC position is lower as engine load increases and/or engine speed decreases and seems independent of the fuel blend composition. Nonetheless, the variation of the pressure difference at the SOC stays moderate, allowing the determination of a unique value to directly read the ID from the indicated pressure profile, without requiring the smoothing process of the third-order derivative of the pressure

Rates of Adherence to Hand Hygiene and Gloving Practices in 2 French Rehabilitation Hospitals by Differentiation between Single Contacts and Series of Successive Contacts with Patients or the Environment

International audienc

Impact of improving glove using on the hand hygiene compliance

International audienc

Measurement and interpretation of hand hygiene compliance rates: importance of monitoring entire care episodes

SummaryOur objective was to assess the importance of monitoring hand hygiene compliance (HHC) during series of successive contacts with patients or surroundings for measurement and interpretation of the compliance rates. A direct observational study of HHC was performed in four intensive care units (ICUs) and four healthcare settings with non-intensive care wards (NICWs). Hand hygiene (HH) opportunities were differentiated into two categories: extra-series opportunities (ESOs) (before or after a single contact, and before the first contact or after the last contact of a series of successive contacts) or as intra-series opportunities (ISOs) (from the opportunity following the first contact to the opportunity preceding the last in the same series). In all, 903 opportunities of HH were performed in ICUs and 760 in NICWs. The proportion of ISOs was 46.0% in ICUs and 22.9% in NICWs. The overall HHC was significantly higher in NICWs than in ICUs (61.2% vs 47.5%, P < 0.00001). The HHC was significantly higher for ESOs than for ISOs (67.7% vs 28.5%, P < 0.00001). The HHC for ISOs was significantly higher in ICUs (32.2% vs 19.0%, P < 0.005). If the distribution of categories of HH opportunities observed in NICWs had been the same as in ICUs, the overall HHC would have been similar in NICWs (46.4%) and in ICUs (47.5%). Monitoring HHC during entire care episodes in series of successive contacts is necessary to avoid a strong overestimation of the overall compliance rates. Concurrently, comparison of compliance data should take into account the proportion of ISOs included in the evaluation study

Impact d’un programme de formation employant plusieurs approches pédagogiques sur l’amélioration de l’observance de l’hygiène des mains dans 4 établissements appartenant à un réseau de lutte contre les infections nosocomiales

Introduction/objectif du travail : Depuis la fin des années 90, les stratégies mises en place pour améliore ’observance de l’hygiène des mains (OHM) ont souvent intégré l’introduction des produits hydro-alcooliques (PHA) ou la promotion de leur utilisation. Aujourd’hui, nombreux sont les établissements qui disposent de ces PHA alors que leur OHM reste modeste. Notre objectif était d’évaluer l’impact d’un programme de formation comportant plusieurs méthodologies pédagogiques sur l’observance de l’HM et le port de gants à usage unique (GUU) dans des établissements disposant de PHA depuis plusieurs années. Matériel et Méthodes : Une étude de type « avant – après » a été réalisée dans 4 établissements comportant des lits d’EHPAD, de gériatrie aigüe ou de rééducation. L’intervention comportait la restitution des résultats de la première phase de l’étude, trois journées de formation de type enseignement dirigé (rappel des notions de base, analyse des risques à partir de scénarios, analyse d’expériences personnelles rapportées par les participants), ateliers HM dans les établissements avec caissons pédagogiques, et organisation de journées thématiques dédiées à l’HM. L’OHM et la qualité des frictions alcooliques ont été notées en différenciant les opportunités d’HM intervenant à l\u27extérieur de séquences de contacts successifs (OES) et les opportunités intra-séquences (OIS). Les pratiques associées au port de GUU ont été étudiées avec différents indicateurs. Résultats : Au total, 1470 opportunités d’HM (760 pendant la première phase et 710 pendant la seconde) ont été observées Une amélioration significative a été notée pour l’OHM dans les OIS (39,0% vs. 19,0% ; p < 10-5), la proportion de contacts avec un risque d’exposition aux produits biologiques pour lesquels il y a eu port de GUU (71,4% vs. 52,0% ; p < 0,001), et la qualité de la friction alcoolique lorsqu’elle était pratiquée (85,0% vs. 71,9% ; p< 10-5). L’OHM après le dernier contact d’une série de contacts successifs (mesurée sur 82 observations) a atteint 97,6% au cours de la deuxième phase (60,9% lors de la première ; p < 10-7). Enfin, l’OHM après retrait des GUU s’est également améliorée (78,0% vs. 64,1% ; p < 0,05). Conclusion : Le programme de formations multiples mis en place a permis d’améliorer significativement plusieurs indicateurs de qualité de la prise en charge du risque de transmission croisée ou d’infection des patients. Afin d’améliorer encore certaines pratiques (OHM pour les OIS), nous envisageons de réaliser une étude qualitative avec des spécialistes en sciences sociales pour mieux comprendre les déterminants du comportement des soignants

Impact of improving glove usage on the hand hygiene compliance

We assessed the impact of improving glove using on the hand hygiene (HH) compliance in a multicenter study including 9 chronic care settings. If gloves had been used correctly during the evaluation, the overall compliance with HH measured after contacts with patients or environment would have only increased from 66.3% to 68.7%. This weak impact suggests that improving glove usage is not in itself an alternative strategy to improve HH compliance

Impact of a multi-faceted training intervention on the improvement of hand hygiene and gloving practices in four healthcare settings including nursing homes, acute-care geriatric wards and physical rehabilitation units

Aims : To assess the impact of a multi-faceted training program on the compliance with hand hygiene and gloving practices. Background.  Hand hygiene is considered as the cornerstone of the prevention of hospital-acquired infections. Several studies have enhanced the poor effectiveness of training programs in improving hand hygiene compliance. Design.  A before–after evaluation study. Methods.  The study was conducted in four healthcare settings before and after an intervention program which included the performance feedback of the first evaluation phase, three six-h training sessions, the assessment of hand hygiene performance with teaching boxes and the organisation of one full-day session devoted to institutional communication around hand hygiene in each setting. Hand hygiene compliance and quality of hand rubbing were evaluated. Hand hygiene opportunities were differentiated into extra-series opportunities (before or after a single contact and before the first contact or after the last contact of a series of consecutive contacts) and intra-series opportunities (from the opportunity following the first contact to the opportunity preceding the last in the same series). Results.  Overall, 969 contacts corresponding to 1,470 hand hygiene opportunities (760 during the first phase and 710 during the second) were observed. A significant improvement of observed practices was recorded for the hand hygiene compliance in intra-series opportunities (39·0% vs. 19·0%; p < 10−5), the proportion of gloves worn if indicated (71·4% vs. 52·0%; p < 0·001) and the quality of hand rubbing (85·0% vs. 71·9%; p < 10−5). Conclusions.  Some of the performances measured for both hand hygiene and gloving practices were improved. We plan to extend this investigation by performing a qualitative study with experts in behavioural sciences to try improving practices for which adherence was still weak after the training program such as hand hygiene in intra-series opportunities. Relevance to clinical practice.  This study underscored the usefulness of implementing contextualised training programs, while more traditional courses have shown little impact

Measurement of hand hygiene compliance and gloving practices in different settings for the elderly considering the location of hand hygiene opportunities during patient care

We monitored hand hygiene and gloving practices by direct observation in 8 health care settings for elderly persons in western France. Compliance with hand hygiene was better than that reported by previous studies, was better for single contacts and before or after a series of successive contacts than inside series, and was closely related to gloving practices. Practices differed among the settings