Long-term Performance Monitoring Research Articles

High Friction Surface Treatment Deterioration Analysis and Characteristics Study

High friction surface treatment (HFST) is used to improve friction on curved roadways, especially on curves that have a history of wet pavement crashes. Observations on the long-term performance monitoring of HFST sections at the National Center for Asphalt Technology (NCAT) Test Track showed friction (skid number, SN) dropped significantly at the end of service life of HFST, creating unsafe driving conditions. There is no clear, observed friction deterioration trend to predict the friction drop when using friction performance measures like SN. Therefore, there is an urgent need to explore and develop supplementary HFST safety performance measures (such as aggregate loss) that can correlate to friction deterioration and provide predictable, cost-effective, and easily measurable results. The objectives of this paper are to (i) analyze the correlation between HFST aggregate loss percentage area and friction value using a dynamic friction tester (DFT), and (ii) study the characteristics of HFST deterioration associated with aggregate loss, at the NCAT Test Track and at selected HFST curve sites in Georgia (using 2D imaging and high-resolution 3D laser scanning). Results show a strong correlation between HFST aggregate loss percentage area and DFT friction coefficient. Where friction measurement is used as the primary safety performance measure, it is recommended that HFST aggregate loss be used as a supplementary performance measure for monitoring the HFST safety performance deterioration. Aggregate loss can be easily identified by characteristics such as color and texture change. Preliminary texture analyses of 3D HFST surface profiles show lower mean profile depth (MPD) and ridge-to-valley depth (RVD) texture indicators can also identify loss of aggregate spots on HFST surface.

MONITORING PERFORMANCE OF LATERITE BASE TRIAL SECTION: A CASE OF ADDIS ABABA, ETHIOPIA

This paper is aimed to present an overview of the provision of a demonstration/research trials with particular reference to pavement performance of a laterite base under a double bituminous surface treatment (DBST) as part of a long-term pavement performance (LTPP) monitoring in Ethiopia. The research components were aimed at increasing the use of locally available materials and solving specific problems related to the performance of some roads constructed with thin asphalt seals. In Ethiopia, most roads are built using crushed rock for road base. The project aim was to demonstrate that whether laterite can be used for base course, assess and evaluate the effect of sealed and unsealed shoulder in cut and fill sections. Out of the various field data measurements carried out in each monitoring period (wet and dry season) the paper reviews the in-situ dynamic cone penetrometer (DCP) test results and visual condition assessment observations. It is demonstrated that for such low volume roads laterite base trial sections are performing well, however DCP test results in these sections reveals that the crushed base control sections perform slightly better than the laterite base trial sections and the sections in cut are stronger than in fill while the shoulder sealing doesn’t provide consistent effect on the layer strengths.

Detection range and efficiency of acoustic telemetry receivers in a connected wetland system

Acoustic telemetry is an important tool for assessing the behavioural ecology of aquatic animals, but the performance of receivers can vary spatially and temporally according to changes in environmental gradients. Studies testing detection efficiency and/ or detection range are, therefore, important for data interpretation, although the most thorough range-testing approaches are often costly or impractical, such as the use of fixed sentinel tags. Here, stationary tag data (from study animals that had either died or expelled their tags) provided a substitute for the long-term monitoring of receiver performance in a wetland environment and was complemented by periodic boat-based range testing, with testing of the effects of environmental variables (water temperature, conductivity, transparency, precipitation, wind speed, acoustic noise) on detection efficiency (DE) and detection range (DR). Stationary tag DE was highly variable temporally, the most influential factors being water temperature and precipitation. Transparency was a strong predictor of DR and was dependent on chlorophyll concentration (a surrogate measure of algal density). These results highlight the value of stationary tag data in assessments of acoustic receiver performance. The high seasonal variability in DE and DR emphasises the need for long-term receiver monitoring to enable robust conclusions to be drawn from telemetry data.

Continuous improvement and adaptation of predictive models in smart manufacturing and model management

Predictive models are increasingly deployed within smart manufacturing for the control of industrial plants. With this arises, the need for long-term monitoring of model performance and adaptation of models if surrounding conditions change and the desired prediction accuracy is no longer met. The heterogeneous landscape of application scenarios, machine learning frameworks, hardware-restricted IIoT platforms, and the diversity of enterprise systems require flexible, yet stable and error resilient solutions that allow the automated adaptation of prediction models. Recommendations are provided for the application and management of predictive models in smart manufacturing. Typical causes for concept drift in real-world smart manufacturing applications are analysed, and essential steps in data and prediction model management are highlighted, to ensure reliability and efficiency in such applications. For this purpose, recommendations and a reference architecture for model management are provided. In addition, experimental results of two model adaptation strategies on an artificial dataset are shown.

Soil water content measurement using polymer optical fibre Bragg gratings

Measuring soil water content is crucially important and can affect soil strength, which is a key parameter in the analysis, design and monitoring of geo-structures. In this study, an optical fibre Bragg grating sensor inscribed in polymer optical fibre was developed, and for the first time, its ability to measure soil water content was investigated. The sensitivity of the sensor to different values of gravimetric soil water content under the different compaction conditions of loose and normal compaction was tested. The effect of soil temperature on the sensor’s performance was considered. To assess the sensor’s implementation, accuracy and reliability, a commercial soil water content probe (SM150), which measures volumetric soil water content was employed. The results indicate that the developed sensor, when calibrated correctly, is able to provide detailed data on any minor variation of soil water content (e.g. 0.5%) with high precision. The outcomes of this study define an additional capability of the polymer optical fibre Bragg grating sensors, which is significantly important for the long-term performance monitoring of geo-structures.

Assessment of long-term deformation of a tunnel in soft rock by utilizing particle swarm optimized neural network

The continuous monitoring of long-term performance of tunnels constructed in soft rock masses shows that the rock mass deformations continue after construction, albeit at a rate that reduces with time. This is in contrast with NATM postulates which assume deformation stabilizes shortly after tunnel construction. This paper proposes the prediction of long-term vertical settlement performance of a tunnel in soft rock mass, through the inclusion of a Burger’s creep viscous-plastic constitutive law to model post-construction deformations. To overcome issues related to the complex characterization of this constitutive model, a neural network NetRHEO is developed and trained on a numerically obtained dataset. A particle swarm algorithm is then employed to estimate the most probable rheological parameter set, by utilizing the long-term in-situ monitoring data from several observation points on a real tunnel. The paper demonstrates the potential of the proposed methodology, using displacement measurements of two adjacent tunnels in karstic rock mass in Croatia. The complex interaction of a railway tunnel Brajdica and a road tunnel Pećine, conditioned by the character of the surrounding rock mass as well by the chronology of their construction, was evaluated to predict the future behavior of these tunnels.

Cover Image

The cover image is based on the Research Article Long-term Performance Monitoring and Assessment of Concrete Beam Bridges using Neutral Axis Indicator by Ye Xia et al., https://doi.org/10.1002/stc.2637.

Correlations and preliminary validation of the laboratory monotonic overlay test (OT) data to reflective cracking performance of in-service field highway sections

Reflective cracking is one of the dominant distress modes occurring when hot-mix asphalt (HMA) overlays are placed over existing cracked flexible and/or jointed rigid pavements. In the laboratory setting, there are various tests – both of dynamic and monotonic loading modes – that can be used to measure, characterize, and quantify the cracking resistance potential of HMA mixes. However, one key challenge with most of these laboratory tests is correlations and validation with field performance data. Quite often, field data availability is a challenge or otherwise, needs costly long-term performance monitoring. Using the Texas flexible pavements and overlays database, namely the Texas Data Storage System (DSS), as the data source, this study was conducted to correlate and preliminarily validate the laboratory monotonic-loading overlay tester (OT) to the field crack performance of in-service highway sections. As excerpted from the DSS, four HMA mixes and six in-service highway sections (overlays) were used. Overall, the monotonic-loading OT test exhibited promising potential as a repeatable test (coefficient of variation [COV] < 30%) for evaluating and quantifying the cracking resistance potential of HMA mixes in the laboratory relative to the field performance of in-service highway sections. In particular, the following HMA fracture parameters, fracture energy (FE), tensile strength (σt), FE Index, and peak load (Pmax) from the monotonic-loading OT test, with COV values less than 30%, were able to statistically differentiate the HMA mixes (statistical groups ≥ 2) and also correlated well (coefficient of determination [R2] > 60%) with the measured field cracking performance data.

Developing a framework for performance assessment of the public long-term care system in Korea: methodological and policy lessons

BackgroundLimited evidence exists on how to assess long-term care system performance. This study aims to report on the process and results of developing a performance assessment framework to evaluate the long-term care system financed by the public long-term care insurance in South Korea.MethodsThe framework was developed through a six-step approach, including setting the goals and scope of performance assessment in the given policy context, reviewing existing performance frameworks, developing a framework with a wide range of potential indicators, refining the framework through a series of Delphi surveys and expert meetings, examining the feasibility of generated indicators through a pilot test, receiving the comments of stakeholders, and finalising the performance framework.ResultsThe finalised framework has 4 domains – coverage, quality of care, quality of life and system sustainability – and 28 indicators, including 10 core indicators to monitor long-term care system performance. Usability and feasibility along with policy relevance were important criteria in selecting these indicators. The proposed framework can be used to assess the performance of the long-term care system in Korea, and the framework and its methodological approach can be benchmarks for other countries developing their own framework.ConclusionsIt is critical to reconcile and prioritise various stakeholders’ views and information needs as well as to balance methodological rigor with practical usefulness and feasibility in the development and implementation of a long-term care performance monitoring system.

Service life extension of SH16 bridges – New Zealand's first hybrid corrosion protection

State Highway 16 (SH16) is a motorway of significant strategic importance, connecting central Auckland to the city's western suburbs and beyond. It carries an average of 90 000 vehicles per day and runs through an environmentally sensitive coastal marine reserve. Two bridges on the route – Whau River Bridge and Causeway Bridge – were rehabilitated due to extensive chloride contamination as a result of exposure to the marine environment. This paper offers a holistic review of the inspection, durability assessment and design processes, and discusses construction, operation and maintenance details. The durability assessment considered deterioration mathematical modelling with regard to service life extensions of 25 and 50 years. A hybrid corrosion protection (HCP) system was selected as the preferred corrosion management solution. The system operates in two phases, initially energised using low-voltage direct current power to arrest ongoing corrosion and thereafter in galvanic mode to provide corrosion prevention. A structural health monitoring system was also designed and installed to offer long-term performance monitoring. The HCP system minimised physical works on site, negated the requirement for extensive replacement of chloride-contaminated concrete, allowed work to take place around the natural tide cycles and offers long-term protection. This is the first HCP system designed and installed in New Zealand and is believed to be the first of its kind for prestressed concrete in tidal waters.

Non-contact measurement of inter-story drift in three-layer RC structure under seismic vibration using digital image correlation

Abstract Earthquakes can cause the unexpected failure of buildings and other structures, and numerous experimental methods have been devised to estimate structural integrity and the likelihood of failure. Unfortunately, the retrofitting of old structures by attaching sensors within walls and columns can be prohibitively expensive, and the analysis of signals obtained from hundreds of devices is time-consuming. In this paper, we introduce a proprietary program based on digital image correlation (DIC) for the measurement of inter-story drift in reinforced concrete structures exposed to seismic vibrations. Inter-story drift refers to translational and angular displacement between floors. We applied the proposed DIC program to the measurement of biaxial deformation and probed inter-story drift in a three-layer structure under the effects of seismic waves. Theoretical modeling, experimental measurements, and numerical analysis were used to verify the accuracy of the measured results as well as the structural performance of the deformed structure. Our DIC results are consistent with those obtained using the infra-red motion capture system, linear variable differential transformers, and accelerometers. The proposed DIC metrology enables the simultaneous observation of displacement, acceleration, and drift angle. The ability to perform non-contact inspection and remote measurement makes this scheme applicable to the long-term monitoring of structural performance under seismic vibration. All associated analysis based on frequency spectra using the fast Fourier transform and short-time Fourier transform can be performed using an inexpensive digital camera and a laptop computer, thereby allowing the in-situ monitoring of structural performance under seismic vibration. The experimental setup of the DIC system takes only a few minutes, and the vision-based metrology can track registered patterns from a remote location. Compared with wired sensors, the DIC system provides a more prolonged and safer distance for observing the inter-layer drift of the RC structure under the reproduced TCU052 earthquake. Compared with an OptiTrack system, the DIC system is portable and can cooperate with a universal combination of optical lens, digital camera, and laptop computer. The accuracy and efficiency of the proposed scheme enable the rapid diagnosis of structures affected by earthquakes, while reducing the costs associated with post-earthquake estimates of damage.

Experimental and Numerical Examination of Naturally-Aged Foam-VIP Composites

This article describes an aging study of a foam-vacuum insulation panel (VIP) composite insulation board installed on a test wall in a natural exposure test facility through a 30-month period. Silica-based VIPs with a polymeric barrier film were used in this study. The study results showed the effectiveness of a VIP-based insulation to reduce the heat gains and losses through a wall compared to regular rigid foam insulation of the same thickness. However, the long-term performance monitoring indicated a gradual decline in the thermal performance of the foam-VIP composite. In addition, one-dimensional numerical models were created to simulate the in situ behavior of the foam-VIP composite. One model utilized constant thermal conductivities of the test wall components and another utilized temperature-dependent thermal conductivities; the latter used measurements of conductivity over temperatures ranging from −15 to 55 °C. The results of the simulations emphasized the need to use both temperature and time-dependent material properties for accurately predicting the long-term performance of VIP-based insulation systems.

Long-term performance monitoring of GFRP-reinforced concrete beams using sensor-mounted supplemental rebars under harsh environmental conditions

Fiber-optic sensors (FOS) are increasingly being used in reinforced-concrete (RC) structures for their accuracy and durability. One of the drawbacks of FOS is their fragility at installation. One recently developed method to address such deficiency is to install the FOS on a short bar (supplemental bar) that is rigidly connected to the structural reinforcement bars prior to concrete pouring. However, the durability of such systems under harsh environmental conditions has not been well established. In order to better understand the behavior of the aforementioned FOS systems under harsh environmental conditions, seven half-scale RC beams with glass fiber-reinforced polymer bars were exposed to four different exposure regimes, in the present study. After 14 months of exposure to harsh environmental conditions, the RC beams were subjected to static flexural testing to evaluate the FOS system behavior under each environmental condition. In addition, the strain responses of the sensors mounted on the supplemental bars and those in the main bars were monitored to validate the newly developed FOS mounting system. The results of this study show that the proposed FOS mounting system can efficiently capture the actual strain in all environmental conditions tested in this study except immersion exposure under high alkali solution. In addition, the flexural deformation and the exposure impact to the beam capacity were evaluated.

An Overview of the Science Performances and Calibration/Validation of Joint Polar Satellite System Operational Products

The Suomi National Polar-orbiting Partnership (S-NPP) satellite, launched in October 2011, initiated a series of the next-generation weather satellites for the National Oceanic and Atmospheric Administration (NOAA) Joint Polar Satellite System (JPSS) program. The JPSS program at the Center for Satellite Applications and Research (JSTAR) leads the development of the algorithms, the calibration and validation of the products to meet the specified requirements, and long-term science performance monitoring and maintenance. All of the S-NPP products have been validated and are in successful operation. The recently launched JPSS-1 (renamed as NOAA-20) satellite is producing high-quality data products that have been available from S-NPP, along with additional products, as a direct result of the instrument upgrades and science improvements. This paper presents an overview of the JPSS product suite, the performance metrics achieved for the S-NPP, and the utilization of the products by NOAA stakeholders and user agencies worldwide. The status of NOAA-20 science data products and ongoing calibration/validation (Cal/Val) efforts are discussed for user awareness. In addition, operational implementation statuses of JPSS enterprise (multisensor and multiplatform) science algorithms for product generation and science product reprocessing efforts for the S-NPP mission are discussed.

Performance Analysis of Piezoelectric Energy Harvesting in Pavement: Laboratory Testing and Field Simulation

This study investigated the energy harvesting performance of a piezoelectric module in asphalt pavements through laboratory testing and multi-physics based simulation. The energy harvester module was assembled with layers of Bridge transducers and tested in the laboratory. A decoupled approach was used to study the interaction between the energy harvester and the surrounding pavement. The effects of embedment location, vehicle speed, and temperature on energy harvesting performance were investigated. The analysis findings indicate that the embedment location and vehicle speed affects the resulted power output of the piezoelectric energy harvesting system. The embedment depth of the energy module affects both the magnitude and frequency of stress pulse on top of the energy module induced by tire loading. On the other hand, higher vehicle speed causes greater loading frequency and thus greater power output; the effect of pavement temperature is negligible. The analysis of total power output before reaching fatigue failure of the energy module can be used to determine the optimum embedment location in the asphalt layer. The proposed energy harvesting system provides great potential to generate green energy from waste kinetic energy in roadway pavements. Field study is recommended to verify these findings with long-term performance monitoring of pavement with embedded energy harvesters.

Sows in mid parity are best foster mothers for the pre- and post-weaning performance of both light and heavy piglets1.

To improve the performance of lightweight piglets during suckling, producers are advised to create uniform litters using young sows. However, fostering piglets to primiparous sows may confer penalties due to their lower milk yield and milk immunoglobulin concentrations compared with multiparous sows. The objective was to determine the effect of foster sow parity (primiparous (F), second (S), and mid parity (M: parity 3 to 5)) on the performance from birth to day 68 of piglets born light (L: ≤1.25 kg) or heavy (H: 1.50-2.00 kg) and on creep feed consumption. Piglets (n = 507) considered L or H were cross-fostered, creating litters of 13 similar-sized piglets/litter and were randomly fostered to one of the foster parities. All litters were offered creep feed with a green dye to discern between consumers and nonconsumers, and the medication administered was recorded. Medication administrated pre- and postweaning did not differ (P > 0.05) across the different experimental groups. A significantly (P ≤ 0.025) lower number of H piglets were removed as a result of preweaning weight loss from F and S, rather than M litters. The interaction between birth weight and foster parity only affected piglet BW at day 10 (P = 0.020); foster parity did not influence BW of L piglets, but influenced that of H piglets. H piglets in F and M litters (3.82 and 3.80 kg) were significantly lighter (P ≤ 0.013) than H piglets in S litters (4.15 kg). As expected, L piglets performed worse pre- and postweaning than H piglets; they were 4.50 kg lighter at day 68. Foster parity significantly affected BW: F piglets were weaned lighter (P = 0.004) than S and M piglets (7.52 vs. 8.02 kg). Postweaning (day 68) however, F piglets achieved similar BW as S piglets (29.7 vs. 29.9 kg), whereas M piglets performed best (31.2 kg, P ≤ 0.079). Significantly fewer (almost none) of the L than the H piglets consumed creep feed (P < 0.001); significantly (P = 0.007) more F and M piglets were considered consumers than S piglets. The results suggest that irrespectively of birth weight, piglets tend to perform better when in M litters, being weaned heavy and having a high creep feed intake; however, more piglets are removed from such litters preweaning. Although S litters were weaned heavy, they were unable to maintain this BW advantage postweaning, due to their low creep feed intake and F litters remained small throughout. Long-term performance monitoring to slaughter is recommended.

Neural network based real-time heart sound monitor using a wireless wearable wrist sensor

The paper presents a new method to estimate acoustic parameters 51 and S2 of the heart sounds using a wearable wrist sensor based on the neural network technique. Using the new method, the heart conditions can be analyzed and monitored in real time and potentially in a long term with a wrist device. The velocities and time delays of the cardiac pulse waves in blood vessels were experimentally acquired and calculated at different artery locations on the human body. Signal attenuation of the pulses from the heart to the wrist artery was analyzed and a pulse-waveform transfer model in artery was proposed. A neural network with two layers and 500 tansig neurons was employed to emulate the inverse acoustic transfer function from the wrist to heart. Comparisons between the parameters of the original heart sounds and estimated cardiac sounds were made to verify the accuracy of the neural network. It is encouraging to find that the acoustic properties of the original and estimated heart sounds have an accuracy up to 100% and the heart rates have an accuracy up to 99%. Using the trained neural network, heart sounds were estimated from the wrist artery by connecting the wrist sensor to a Bluetooth audio module to implement a wearable heart sound estimator. Performance of the new estimation method was verified. The proposed wrist sensor aims as a wireless wearable monitor on wrists for continuous and long-term medical diagnosis and athlete performance monitoring.

Challenges due to problematic soils: a case study at the crossroads of geotechnology and sustainable pavement solutions

Geotechnical characteristics of subsoils should be adequately incorporated in the rehabilitation strategies of existing pavements which have performed poorly due to problematic subsurface conditions. However, there appears to be a disconnect between the advances in our understanding of the mechanics of soft or problematic soils and the rehabilitation design of the overlying pavement structure, leading to repeated cycles of premature distresses, underperformance, and failures. A case study is presented for the rehabilitation of a flexible pavement built over soft organic soils in Southeastern Florida, USA. The study incorporates forensic investigation of the deteriorated pavement structure, subsurface investigations with cone penetration testing, design and construction of reinforced overlays in field test sections, and long-term performance monitoring with non-destructive dynamic tests. Efforts are made to correlate site characteristics with pavement performance. Based on the secondary compression behavior of the organic soils, cement deep mixing criteria are proposed for a more durable and sustainable solution.

Robust fibre optic sensor arrays for monitoring early-age performance of mass-produced concrete sleepers

This study investigates integrating fibre optic sensing technology into the production process of concrete railway sleepers. Robust fibre Bragg grating strain and temperature sensor arrays were developed specifically for this application and were designed for long-term monitoring of sleeper performance. The sensors were used to monitor sleeper production and to help gain a deeper understanding of their early-age behaviour which can highly influence long-term performance. In total, 12 sleepers were instrumented and strain data were collected during the entire manufacturing process including concrete casting and curing, prestressing strand detensioning and qualification testing. Following the production process, sleepers were stored temporarily and monitored for 4 months until being placed in service. The monitoring results highlight the intrinsic variability in strain development among identical sleepers, despite high levels of production quality control. Using prestress loss as a quality control indicator, the integrated sensing system demonstrated that sleepers were performing within Eurocode-based design limits prior to being placed in service. A three-dimensional nonlinear finite element model was developed to provide additional insight into the sleepers’ early-age behaviour. Based on the fibre Bragg grating–calibrated finite element model, more realistic estimates for the creep coefficient were provided and found to be 48% of the Eurocode-predicted values.

Modeling Coupled Processes in Municipal Solid Waste Landfills: An Overview with Key Engineering Challenges

Disposal of municipal solid waste (MSW) in engineered landfills is one of the most widely used waste management practices in the USA and worldwide. During its design life, landfilled MSW undergoes various complex mechanisms controlled by physical (hydraulic and mechanical), chemical, thermal, and biological processes and their interrelated behaviors. A thorough understanding of these coupled MSW interactions is critical in designing a stable, effective and well-operational landfill. However, to date, the current practices associated with mathematical modeling as well as long-term monitoring of landfill performance(s) are mostly empirical and limited to site-specific conditions. Moreover, they fail to substantially quantify the changes in the geotechnical properties of MSW that result from coupled processes, especially the highly uncertain biological processes that result in MSW degradation in landfills. Furthermore, the spatially and temporally varied waste composition, heterogeneous and anisotropic nature of field MSW together with leachate and landfill gas production due to biodegradation results in atypical differential MSW settlement and, therefore, can adversely impact the long-term performance of landfills. Over the years, numerous experimental studies, field studies and mathematical modeling studies that focus on these landfill processes have been performed to optimize MSW landfill performance. In this study, a critical review of the previous research efforts on coupled processes is provided to help landfill engineers understand, design and operate MSW landfills safely and efficiently. Moreover, key research issues and challenges related to numerical modeling of landfilled MSW undergoing coupled processes are presented.