213 research outputs found

    Thermodynamic-based method for supporting design and operation of thermal grids in presence of distributed energy producers

    Get PDF
    District heating networks are well-established technologies to efficiently cover the thermal demand of buildings. Recent research has been devoting large efforts to improve the design and management of these systems for integrating low-temperature heat coming from distributed sources such as industrial processes and renewable energy plants. Passing from a centralized to a decentralized approach in the heat supply, it is important to develop indicators that allow an assessment of the rational use of the available heat sources in supplying heating networks, and a quantification of the effect of inefficiencies on the unit cost of heat. To answer these questions, Exergy Cost Theory is here proposed. Thanks to the unit exergetic cost of heat, energy managers can (i) quantify the effects of thermodynamic inefficiencies occurring in the production and distribution on the final cost of heat, (ii) compare alternative systems for heat production, and (iii) monitor the performance of buildings’ substation over time. To show the capabilities of the method, some operating scenarios are compared for a cluster of five buildings in the tertiary sector interconnected by a thermal grid, where heat is produced by a cogeneration unit, an industrial process, and distributed heat pumps. Results suggest that moving from the centralized production of heat based on fossil fuels to a decentralized production with air-to-water heat pumps, the unit cost of heat can be decreased by almost 30% thanks to the improvement of thermodynamic efficiency. In addition, the analysis reveals a great sensitivity of unit exergetic cost to the maintenance in substations. The developed tool can provide thermodynamic-sound support for the design, operation, and monitoring of innovative district heating networks

    Easy Cases of Deadlock Detection in Train Scheduling

    Get PDF
    A deadlock occurs when two or more trains are preventing each other from moving forward by occupying the required tracks. Deadlocks are rare but pernicious events in railroad operations and, in most cases, are caused by human errors. Recovering is a time-consuming and costly operation, producing large delays and often requiring crew rescheduling and complex switching moves. In practice, most deadlocks involve only two long trains missing their last potential meet location. In this paper, we prove that, for any network configuration, the identification of two-train deadlocks can be performed in polynomial time. This is the first exact polynomial algorithm for such a practically relevant combinatorial problem. We also develop a pseudo-polynomial but efficient oracle that allows real-time early detection and prevention of any (potential) two-train deadlock in the Union Pacific (a U.S. class 1 rail company) railroad network. A deadlock prevention module based on the work in this paper will be put in place at Union Pacific to prevent all deadlocks of this kind.acceptedVersio

    Real-Time Hardware-in-the-Loop Laboratory Testing for Multisensor Sense and Avoid Systems

    Get PDF
    This paper focuses on a hardware-in-the-loop facility aimed at real-time testing of architectures and algorithms of multisensor sense and avoid systems. It was developed within a research project aimed at flight demonstration of autonomous non-cooperative collision avoidance for Unmanned Aircraft Systems. In this framework, an optionally piloted Very Light Aircraft was used as experimental platform. The flight system is based on multiple-sensor data integration and it includes a Ka-band radar, four electro-optical sensors, and two dedicated processing units. The laboratory test system was developed with the primary aim of prototype validation before multi-sensor tracking and collision avoidance flight tests. System concept, hardware/software components, and operating modes are described in the paper. The facility has been built with a modular approach including both flight hardware and simulated systems and can work on the basis of experimentally tested or synthetically generated scenarios. Indeed, hybrid operating modes are also foreseen which enable performance assessment also in the case of alternative sensing architectures and flight scenarios that are hardly reproducible during flight tests. Real-time multisensor tracking results based on flight data are reported, which demonstrate reliability of the laboratory simulation while also showing the effectiveness of radar/electro-optical fusion in a non-cooperative collision avoidance architecture

    Wearable and interactive mixed reality solutions for fault diagnosis and assistance in manufacturing systems: Implementation and testing in an aseptic bottling line

    Get PDF
    Abstract Thanks to the spread of technologies stemming from the fourth industrial revolution, also the topic of fault diagnosis and assistance in industrial contexts has benefited. Indeed, several smart tools were developed for assisting with maintenance and troubleshooting, without interfering with operations and facilitating tasks. In line with that, the present manuscript aims at presenting a web smart solution with two possible applications installed on an Android smartphone and Microsoft HoloLens. The solution aims at alerting the operators when an alarm occurs on a machine through notifications, and then at providing the instructions needed for solving the alarm detected. The two devices were tested by the operators of an industrial aseptic bottling line consisting of five machines in real working conditions. The usability of both devices was positively rated by these users based on the System Usability Scale (SUS) and additional appropriate statements. Moreover, the in situ application brought out the main difficulties and interesting issues for the practical implementation of the solutions tested

    High-Risk Siblings without Autism: Insights from a Clinical and Eye-Tracking Study

    Get PDF
    Joint attention (JA)—the human ability to coordinate our attention with that of other people—is impaired in the early stage of Autism Spectrum Disorder (ASD). However, little is known about the JA skills in the younger siblings of children with ASD who do not develop ASD at 36 months of age [high-risk (HR)-noASD]. In order to advance our understanding of this topic, a prospective multicenter observational study was conducted with three groups of toddlers (age range: 18–33 months): 17 with ASD, 19 with HR-noASD and 16 with typical development (TD). All subjects underwent a comprehensive clinical assessment and an eye-tracking experiment with pre-recorded stimuli in which the visual patterns during two tasks eliciting initiating joint attention (IJA) were measured. Specifically, fixations, transitions and alternating gaze were analyzed. Clinical evaluation revealed that HR-noASD subjects had lower non-verbal cognitive skills than TD children, while similar levels of restricted and repetitive behaviors and better social communication skills were detected in comparison with ASD children. Eye-tracking paradigms indicated that HR-noASD toddlers had visual patterns resembling TD in terms of target-object-to-face gaze alternations, while their looking behaviors were similar to ASD toddlers regarding not-target-object-to-face gaze alternations. This study indicated that high-risk, unaffected siblings displayed a shared profile of IJA-eye-tracking measures with both ASD patients and TD controls, providing new insights into the characterization of social attention in this group of toddlers

    Sex/Gender Differences in the Language Profiles of Italian Children with Autism Spectrum Disorder: A Retrospective Study

    Get PDF
    Sex/gender (S/G) differences in ASD language profiles have been poorly investigated. The present study aims to explore whether male (M) and female (F) children with ASD and with normal non-verbal cognitive abilities differ in their linguistic profiles. A sample of 76 Italian children with ASD (range: 4.9-8 years), including 50 Ms and 26 Fs, was retrospectively recruited. Language profiles were analyzed using standardized tests for the evaluation of receptive and expressive vocabulary as well as grammar. Grammatical comprehension was the most impaired domain compared to the other language measures in both M and F children. Comparing language profiles between S/G, Fs showed significantly better scores than Ms in grammatical production (p = 0.002), and Ms showed better active negative sentence comprehension (p = 0.035). Moreover, comparing the language profiles between Ms and Fs with a receptive disorder, Fs had significantly worse grammatical comprehension and better grammatical production than Ms. Even among children without a receptive disorder, Fs had significantly higher grammatical production scores. The S/G differences in language profile, particularly better expressive language in Fs than Ms, can partially contribute to the delayed ASD diagnosis or underdiagnosis of Fs without intellectual disability. Finally, the results document the importance of accurately investigating both expressive and receptive abilities in children with ASD

    Prior history of sexually transmitted diseases in women living with AIDS in Sao Paulo, Brazil

    Get PDF
    Objectives: To describe the epidemiological profile, risk behaviors, and the prior history of sexually transmitted diseases (STDs) in women living with acquired immunodeficiency syndrome (AIDS). Methods: Cross-sectional study, performed at the Centro de Referencia e Treinamento em DST/AIDS of Sao Paulo. The social, demographic, behavioral, and clinical data such as age, schooling, marital status, age at first sexual intercourse, number of sexual partners, parity, use of drugs, time of HIV diagnosis, CD4 count, and viral load determination were abstracted from the medical records of women living with AIDS who had gynecological consultation scheduled in the period from June 2008 to May 2009. Results: Out of 710 women who were scheduled to a gynecological consultation during the period of the study, 598 were included. Previous STD was documented for 364 (60.9%; 95% CI: 56.9%-64.8%) women. The associated factors with previous STDs and their respective risks were: human development index (HDI) <0.50 (ORaj = 5.5; 95% CI: 2.8-11.0); non-white race (ORaj = 5.2; 95% CI: 2.5-11.0); first sexual intercourse at or before 15 years of age (ORaj = 4.4; 95% CI: 2.3-8.3); HIV infection follow-up time of nine years or more (ORaj = 4.2; 95% CI: 2.3-7.8)]; number of sexual partners during the entire life between three and five partners (ORaj = 2.2; 95% CI: 1.1-4.6), and six or more sexual partners (ORaj = 3.9; 95% CI: 1.9-8.0%); being a sex worker (ORaj = 1.9; 95% CI: 1.1-3.1). Conclusions: A high prevalence of a prior history of STDs in the studied population was found. It is essential to find better ways to access HIV infection prevention, so that effective interventions can be more widely implemented. (C) 2012 Elsevier Editora Ltda. All rights reserved.National Institute of Health [3D43TW000010-21S1, AI06699]National Institute of Healt

    Interpretação hidrogeoquímica das águas subterrâneas da ilha de Marajó.

    Get PDF
    Information obtained in a research survey carried oat by IDESP was used to investigate, groundwater hydrogeochemistry on Marajó island. The samples were collected in both dug and drilled wells. The results of physico-chemistry analyses indicated a wide range of concentrations in the water quality parameters which reflects the hydrogeologic complexity on the area. The largest total dissolved solids concentrations ocuured in the central and northern part of the area while the lowest levels were found in the south, southeast and northwest. The waters were predominantly of the sodium-chloride type followed by the mixed-chloride and mixed-bicarbonate types. The Schöeller semi-logarithmic diagram was used to identify waters with similar chemical characteristics. The variation in groundwater composition along the subsurficial flow path indicated a dissolution phenomenon with the dissolved ions increasing from the active groundwater flushing zone to the zone of very sluggish flow. This resulted in a variable mixture of fresh and brackish groundwater. The reduction of sulfate by oxidation of organic matter,the base exchange and adsorption are phenomena that exert an important control on the water chemistry.As pesquisas desenvolvidas pelo IDESP na Ilha de Marajó possibilitaram estudos de hidrogeoquímica das águas subterrâneas. As amostras foram coletadas em poços escavados e em poços tubulares. Os resultados das análises físico-químicas evidenciaram significativas variações nas concentrações dos parâmetros de qualidade de água, refletindo a complexidade hidrogeológica da área. As maiores concentrações de sólidos totais dissolvidos ocorrem na parte central e norte da área, sendo pequena na parte sul, sudeste e noroeste. As águas são predominantemente do tipo sódio-cloretada, seguidas pelos tipos mista-cloretada e mista-bicarbonatada. A utilização de diagramas semi-logarítimicos de Schoeller possibilitou o agrupamento das águas subterrâneas com características químicas similares. A evolução da composição das águas subterrâneas evidencia o aumento da concentração dos íons dissolvidos das zonas de fluxo ativo em áreas de recarga para as zonas de fluxo muito lento. Misturas de águas doces com águas salobras conatas ocorrem em proporções variadas. A redução de sulfatos pela matéria orgânica e a troca de bases e adsorção são fenômenos que atuam na concentração dos íons dissolvidos

    Serological screening for Celiac Disease in 382 pre-schoolers with Autism Spectrum Disorder

    Get PDF
    Background: Recent investigations suggest a possible common genetic background between Autism Spectrum Disorders (ASD) and Celiac Disease (CD). However, studies regarding this association are scarce and often limited by the small sample sizes and/or large heterogeneity among ASD groups in terms of demographic and clinical features. The present study aims to investigate the overall CD prevalence (biopsy proven-CD patients plus screening detected tTG and EMA positive cases) in a large population of pre-schoolers with ASD referred to a tertiary care University Hospital. Methods: We retrospectively collected data about 382 children (mean age: 46.97 ± 13.55 months; age-range: 18-72 months) consecutively diagnosed as ASD (according to the Diagnostic and Statistical Manual of Mental Disorders 4th edition criteria) over the period 2010-2013, and who performed a serological CD screening. Results: The overall CD prevalence was 2.62%, which is statistically significant higher to that reported in the Italian paediatric population (p = 0.0246). Half of these children had no symptoms or risk factors related to CD when they performed the serological screening. Conclusions: If replicated, these data suggest the importance of regular screening for CD in young patients with ASD, and are of relevance for clinical and public health
    corecore