Verdichtingstemperatuur en mechanische eigenschappen

Dat de dichtheid van asfalt van belang is voor de kwaliteit is algemeen bekend. Evenzo dat de temperatuur tijdens verdichten van belang is voor de vereiste energie om noodzakelijke dichtheid te bereiken. Bij gelijke einddichtheid heeft de temperatuur aan het begin van het walsen effect op de eigenschappen. Dit inzicht kan grote gevolgen hebben voor de asfaltverwerking

RFID sensors to measure the energy consumption of warm mix and recycled asphalt

Governments, regulatory bodies and road authorities all push for and promote sustainability. Contractors respond with strategies to reduce their carbon footprints. Besides optimising their asphalt production and logistics processes, companies are investing in the development of low energy asphalt mixes.Warm Mix Asphalt (WMA) is such an asphalt mixture produced at lower temperatures, thereby requiring less energy. It has recently become very popular in the Netherlands with various types of WMA products being developed by construction companies. In essence, the asphalt mix is modified to reduce the viscosity and the mixture is therefore more flexible at lower temperatures enabling more time available for a very important part of the construction process viz. COMPACTION.While essential research effort has been put into developing techniques for adjudicating WMA, optimising their composition and rationalising the design; less effort has been put into the operational handling and consequences regarding energy consumption and durability. In short, little is known about actual energy consumption during the asphalt compaction process.By placing RFID sensors into the asphalt mixture, temperatures and pressures can be measured during laboratory testing and construction, but also during usage and maintenance of the road where additional RFID sensors can be added to measure weather conditions and other long-term parameters

Aligning laboratory and field compaction practices for asphalt - the influence of compaction temperature on mechanical properties

The approach used to identify a compaction temperature in the laboratory, based on binder viscosity, provides a single compaction temperature whereas, on-site, a roller operates within a temperature window. The effect on the density and mechanical properties of rolling during a temperature window remains unclear. Consequently, asphalt concrete binder mixtures were compacted in different temperature windows in the laboratory using a Roller Sector Compactor, and the observed phenomena were then related to field study observations. The results show that while similar densities can be achieved in a broad range of temperature windows, other mechanical properties such as fracture energy may decline up to 30% if compacted outside the optimum temperature window. These results indicate that a compaction temperature window should form part of mix design and quality control. The paper proposes specifying a compaction window based on temperatures and the resulting mechanical properties rather than a single compaction temperature

Professionalisering asfaltuitvoeringsproces:synthetiseren informatietechnologie, ervaringskennis en laboratoriumprocedures

Dit onderzoek gaat over de noodzaak om het asfaltuitvoeringsproces en de operationele strategieën van asfaltploegen op de bouwplaats te verbeteren. Sinds 2005 wordt er in ASPARi-verband inspanning geleverd om het asfaltuitvoeringsproces te professionaliseren. In de huidige markt zoeken opdrachtnemers (aannemers) naar gerichte procesbeheersing, maar de noodzakelijke kennis over het ervaring gedreven proces ontbreekt grotendeels. De inspanningen van het ASPARi-netwerk in de afgelopen jaren hebben geresulteerd in: Een verbeterd PQi (Process Quality improvement) framework geïmplementeerd in de praktijk, een dataset van ca. 50 systematisch gemonitorde projecten, een overzicht van variabiliteit in het uitvoeringsproces, een leermodel, empirisch geteste relaties in het laboratorium tussen uitvoeringsprocessen en mechanische eigenschappen en procedures om verdichting in het laboratorium beter te verbinden met asfaltverdichting op de bouwplaats. De resultaten van het onderzoek hebben geleidt tot een triangulatie-aanpak voor opdrachtnemers om operationele strategieën van asfaltploegen stapsgewijs te kunnen verbeteren door: (1) technologie uitbreiding en implementatie in het asfaltuitvoeringsproces; (2) het toepassen van consistente en methoden gebaseerde operationele strategieën inclusief feedbacksessies met asfaltploegen; en (3) het relateren van ontwerpprocedures in het laboratorium aan het uitvoeringsproces op de bouwplaats. Dit leidt tot procesverbeteringen, een meer consistente asfaltkwaliteit en meer professionele vakmensen en asfaltwegenbouwbedrijven. De paper zal ingaan op de ontwikkelde triangulatie-aanpak om het asfaltuitvoeringsproces te verbeteren, onderbouwd en toegelicht met behulp van voorbeelden en lessen uit de praktijk. Vervolgens geeft de paper een vooruitblik naar ‘de bouwplaats van de toekomst’. Tot slot beschrijft de paper mogelijke EMVI-criteria voor opdrachtgevers om de professionalisering van het asfaltuitvoeringsproces te stimuleren

An information fusion approach for filtering GNSS data sets collected during construction operations

Global Navigation Satellite Systems (GNSS) are widely used to document the on- and off-site trajectories of construction equipment. Before analyzing the collected data for better understanding and improving construction operations, the data need to be freed from outliers. Eliminating outliers is challenging. While manually identifying outliers is a time-consuming and error-prone process, automatic filtering is exposed to false positives errors, which can lead to eliminating accurate trajectory segments. This paper addresses this issue by proposing a hybrid filtering method, which integrates experts’ decisions. The decisions are operationalized as parameters to search for next outliers and are based on visualization of sensor readings and the human-generated notes that describe specifics of the construction project. A specialized open-source software prototype was developed and applied by the authors to illustrate the proposed approach. The software was utilized to filter outliers in sensor readings collected during earthmoving and asphalt paving projects that involved five different types of common construction equipmen

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Circulating microRNAs in sera correlate with soluble biomarkers of immune activation but do not predict mortality in ART treated individuals with HIV-1 infection: A case control study

Introduction: The use of anti-retroviral therapy (ART) has dramatically reduced HIV-1 associated morbidity and mortality. However, HIV-1 infected individuals have increased rates of morbidity and mortality compared to the non-HIV-1 infected population and this appears to be related to end-organ diseases collectively referred to as Serious Non-AIDS Events (SNAEs). Circulating miRNAs are reported as promising biomarkers for a number of human disease conditions including those that constitute SNAEs. Our study sought to investigate the potential of selected miRNAs in predicting mortality in HIV-1 infected ART treated individuals. Materials and Methods: A set of miRNAs was chosen based on published associations with human disease conditions that constitute SNAEs. This case: control study compared 126 cases (individuals who died whilst on therapy), and 247 matched controls (individuals who remained alive). Cases and controls were ART treated participants of two pivotal HIV-1 trials. The relative abundance of each miRNA in serum was measured, by RTqPCR. Associations with mortality (all-cause, cardiovascular and malignancy) were assessed by logistic regression analysis. Correlations between miRNAs and CD4+ T cell count, hs-CRP, IL-6 and D-dimer were also assessed. Results: None of the selected miRNAs was associated with all-cause, cardiovascular or malignancy mortality. The levels of three miRNAs (miRs -21, -122 and -200a) correlated with IL-6 while miR-21 also correlated with D-dimer. Additionally, the abundance of miRs -31, -150 and -223, correlated with baseline CD4+ T cell count while the same three miRNAs plus miR- 145 correlated with nadir CD4+ T cell count. Discussion: No associations with mortality were found with any circulating miRNA studied. These results cast doubt onto the effectiveness of circulating miRNA as early predictors of mortality or the major underlying diseases that contribute to mortality in participants treated for HIV-1 infection

Development and Validation of a Risk Score for Chronic Kidney Disease in HIV Infection Using Prospective Cohort Data from the D:A:D Study

Ristola M. on työryhmien DAD Study Grp ; Royal Free Hosp Clin Cohort ; INSIGHT Study Grp ; SMART Study Grp ; ESPRIT Study Grp jäsen.Background Chronic kidney disease (CKD) is a major health issue for HIV-positive individuals, associated with increased morbidity and mortality. Development and implementation of a risk score model for CKD would allow comparison of the risks and benefits of adding potentially nephrotoxic antiretrovirals to a treatment regimen and would identify those at greatest risk of CKD. The aims of this study were to develop a simple, externally validated, and widely applicable long-term risk score model for CKD in HIV-positive individuals that can guide decision making in clinical practice. Methods and Findings A total of 17,954 HIV-positive individuals from the Data Collection on Adverse Events of Anti-HIV Drugs (D:A:D) study with >= 3 estimated glomerular filtration rate (eGFR) values after 1 January 2004 were included. Baseline was defined as the first eGFR > 60 ml/min/1.73 m2 after 1 January 2004; individuals with exposure to tenofovir, atazanavir, atazanavir/ritonavir, lopinavir/ritonavir, other boosted protease inhibitors before baseline were excluded. CKD was defined as confirmed (>3 mo apart) eGFR In the D:A:D study, 641 individuals developed CKD during 103,185 person-years of follow-up (PYFU; incidence 6.2/1,000 PYFU, 95% CI 5.7-6.7; median follow-up 6.1 y, range 0.3-9.1 y). Older age, intravenous drug use, hepatitis C coinfection, lower baseline eGFR, female gender, lower CD4 count nadir, hypertension, diabetes, and cardiovascular disease (CVD) predicted CKD. The adjusted incidence rate ratios of these nine categorical variables were scaled and summed to create the risk score. The median risk score at baseline was -2 (interquartile range -4 to 2). There was a 1: 393 chance of developing CKD in the next 5 y in the low risk group (risk score = 5, 505 events), respectively. Number needed to harm (NNTH) at 5 y when starting unboosted atazanavir or lopinavir/ritonavir among those with a low risk score was 1,702 (95% CI 1,166-3,367); NNTH was 202 (95% CI 159-278) and 21 (95% CI 19-23), respectively, for those with a medium and high risk score. NNTH was 739 (95% CI 506-1462), 88 (95% CI 69-121), and 9 (95% CI 8-10) for those with a low, medium, and high risk score, respectively, starting tenofovir, atazanavir/ritonavir, or another boosted protease inhibitor. The Royal Free Hospital Clinic Cohort included 2,548 individuals, of whom 94 individuals developed CKD (3.7%) during 18,376 PYFU (median follow-up 7.4 y, range 0.3-12.7 y). Of 2,013 individuals included from the SMART/ESPRIT control arms, 32 individuals developed CKD (1.6%) during 8,452 PYFU (median follow-up 4.1 y, range 0.6-8.1 y). External validation showed that the risk score predicted well in these cohorts. Limitations of this study included limited data on race and no information on proteinuria. Conclusions Both traditional and HIV-related risk factors were predictive of CKD. These factors were used to develop a risk score for CKD in HIV infection, externally validated, that has direct clinical relevance for patients and clinicians to weigh the benefits of certain antiretrovirals against the risk of CKD and to identify those at greatest risk of CKD.Peer reviewe