Real Environmental Conditions Research Articles

Understanding the effects of aerodynamic and hydrodynamic shear forces on Pseudomonas aeruginosa biofilm growth.

Biofilms are communities of bacterial cells encased in a self‐produced polymeric matrix and exhibit high tolerance towards environmental stress. Despite the plethora of research on biofilms, most biofilm models are produced using mono‐interface culture in static flow conditions, and knowledge of the effects of interfaces and mechanical forces on biofilm development remains fragmentary. This study elucidated the effects of air–liquid (ALI) or liquid–liquid (LLI) interfaces and mechanical shear forces induced by airflow and hydrodynamic flow on biofilm growing using a custom‐designed dual‐channel microfluidic platform. Results from this study showed that comparing biofilms developed under continuous nutrient supply and shear stresses free condition to those developed with limited nutrient supply, ALI biofilms were four times thicker, 60% less permeable, and 100 times more resistant to antibiotics, while LLI biofilms were two times thicker, 20% less permeable, and 100 times more resistant to antibiotics. Subjecting the biofilms to mechanical shear stresses affected the biofilm structure across the biofilm thickness significantly, resulting in generally thinner and denser biofilm compared to their controlled biofilm cultured in the absence of shear stresses, and the ALI and LLI biofilm's morphology was vastly different. Biofilms developed under hydrodynamic shear stress also showed increased antibiotic resistance. These findings highlight the importance of investigating biofilm growth and its mechanisms in realistic environmental conditions and demonstrate a feasible approach to undertake this study using a novel platform.

Comparison and performance analysis of pheromone value and cannibalism based black widow optimisation approaches for modelling and parameter estimation of solar photovoltaic mathematical models

Assessment of precise solar photovoltaic (PV) modelling parameters through experimental current-voltage (I-V) data or by using the manufacturer’s datasheet, is a matter of strong research interest among researchers. Where, the challenge rests in precise evaluation, control, and creation of a more reliable PV model with well optimised parameters. Pheromone Value Black Widow Optimisation (pv-BWO) and Cannibalism Black Widow Optimisation (cn-BWO), are the two proposed methodologies for detailed modelling, and the estimation of modelling parameters for the single-diode model (SDM) and double-diode model (DDM) of solar PV. Validation of the proposed techniques are observed through I-V and power-voltage (P-V) performance characteristics, of three case studies that are considered for the investigation. The RTC France and PWP 201 modules are the two cases that are extensively examined in the literature, where the experimental data is recorded for SFTI 60 P in real environmental conditions and referred to as the third case. Moreover, results of cn-BWO and pv-BWO are also compared with some well-established parameter estimation methods in the literature, where it is affirmed that pv-BWO exhibits a more reliable and precise solution for parameter estimation problem with the least cost function, whereas cn-BWO unveils high convergence speed when compared with pv-BWO.

Deformation recoverability of longitudinal joints in segmental tunnel linings: An experimental study

The shield-driven tunnel is a fabricated lining structure. The existence of longitudinal joints between segments in a ring makes the entire tunnel lining vulnerable to deformations, because the rigidity of longitudinal joints is lower than that of the main concrete segments. Large transverse deformation, accompanied by joint opening, is a common disease of shield tunnels. The aim of this work is to explore the deformational behaviors and mechanical properties of tunnel longitudinal joints under overloading, unloading, and soil grouting conditions, with emphasis on the recoverability of joint deformation. For this purpose, a series of laboratory tests have been carried out on the full-scale longitudinal joints at tunnel crown adopted in Shanghai metro tunnels, including three parallel tests with different overload levels and one cyclic overloading and unloading test. The full-scale testing considers the actual stress state of the longitudinal joint under different working conditions in real environments. The specimen of the longitudinal joint at tunnel crown adopts the actual three-segment-two-oblique-seam structure, which is different from the simplified two-segment-one-straight-seam form used in previous studies. Multiple deformation indicators, including joint opening, concrete strain, and bolt strain, are monitored and analyzed. Based on the test results, the effects of restoration actions, i.e., unloading and soil grouting, on joint deformation recovery under different overload levels are discussed. The change of recovery efficiency with the degree of joint deformation is also obtained. In addition, the deformation recoverability and rotational stiffness are compared between the longitudinal joint at tunnel crown which is subjected to positive bending moment and the longitudinal joint at tunnel springline which is subjected to negative bending moment. The test results show that the larger the joint deformation caused by overload, the lower the recovery efficiency. From a mechanical perspective, soil grouting is an effective measure to recover the large deformation of shield tunnels.

Physiological and psychological responses and cognitive performance with a window view

A window view, including nature, decreases stress and improves well-being. The aim of this study was to evaluate the effect of a window view on physiological and psychological responses and cognitive performance. Twenty-six participants were exposed to two viewing conditions (closed blinds and window view) in real and virtual environments. Skin temperature, skin conductance, heart-rate variability, and electroencephalography were examined. Cognitive tests were conducted for the participants after an environmental exposure for 5 min. During the exposure and tests, participants with a window view recorded higher skin temperature, lower skin conductance, and lower heart rate than those with closed blinds by 0.1 °C, 0.12 μS, and 0.98 bpm, respectively. Physiological responses indicated that participants with a window view were less stressed than those with closed blinds. Short-term working memory with a window view, compared with closed blinds, improved significantly (by 6%) in the real environment; however, the increase was not significant in the virtual environment. Short-term working memory was affected by self-reported concentration and relaxed mood based on visual comfort. Moreover, the physiological responses in the virtual environment were similar to those in the real environment. This result indicates that a window view improves stressful conditions in both real and virtual environments.

Wastewater valorisation in an integrated multitrophic aquaculture system; assessing nutrient removal and biomass production by duckweed species

The aquaculture industry is considered a key sector for the supply of high quality, nutritious food. However, growth of the aquaculture sector has been slow, particularly in Europe, and this is amongst others linked to concerns about environmental impacts of this industry. Integrated Multitrophic Aquaculture (IMTA) has been identified as an important technology to sustainably improve freshwater fish production. In IMTA, economically valuable extractive species feed on waste produced by other species, remediating wastewater, and minimising the environmental impact of aquaculture. This study presents quantitative information on the nitrogen and phosphorus removal efficiency of a duckweed-based, pilot, semi-commercial IMTA system. Duckweed species are free-floating freshwater species belonging to the family of Lemnaceae. The aim of this study was to test the potential of duckweed-based IMTA under realistic environmental conditions. Three different approaches were used to assess remediation capacity; 1) assessment of water quality pre and post treatment with duckweed showed that the system can remove 0.78 and 0.38 T y−1 of Total Nitrogen (TN) and Total Phosphorus (TP), respectively 2) based on nitrogen and phosphorus content of newly grown duckweed biomass, it was shown that 1.71 and 0.22 T y−1 of TN and TP can be removed, respectively 3) extrapolation based on laboratory established nitrogen and phosphorus uptake rates determined that 0.88 and 0.08 T y−1 of TN and TP can be removed by the system. There is substantive agreement between the three assessments, and the study confirms that duckweed can maintain good quality water in an IMTA system, while yielding high protein content (21.84 ± 2.45%) biomass. The quantitative data on nitrogen and phosphorus removal inform the design of further IMTA systems, and especially create a scientific basis to determine the balance between aquaculture and extractive species.

New approach towards mitigating photovoltaic panels soiling by dew flowing.

Soiling has a crucial importance regarding its impact mainly for countries that have high soiling levels, dust storms, water scarcity and a great solar energy potential as the case of Morocco. Soiling mitigation is therefore mostly required during spring, due to higher pollen concentration, and summer, due to the lack of heavy precipitation. In this work, systematic measurements of soiling ratio were made in Rabat, city of north-western Morocco, during almost 1year. Soiling has been evaluated considering the effect of dual-axis tracking that was compared to photovoltaic (PV) on fixed structure. A soiling rate of about 0.22%/day has been found for static PV while only 0.1% was found for PV on tracker. An additional approach of cleaning has been proposed in this paper which aims to use dew water. Using glass samples that were exposed to real environmental conditions, similar to the exposure conditions of PV panels, the soiling ratio was determined. At sunrise time, the subsequent change of the glass sample, from the horizontal position at night into the position of 30° tilt angle during the day, is performed to promote dew flow by the force of gravity acting on the droplets of dew. It has been found that relying only on the change of tilt angle, the average soiling losses were only 3.8% compared with 11.8% for fixed PV. This approach can reduce soiling similarly to solar trackers.

Application of an Upwind integration method to plane parallel Hall-MHD

Aims:We study the impact of an Upwind scheme on the numerical convergence of simulations of the Hall and Ohmic effect in neutron stars crusts. While simulations of these effects have explored a variety of geometries and wide ranges of physical parameters, they are limited to relatively low values of the Hall parameter, playing the role of the magnetic Reynolds number, which should be not exceed a few hundred for numerical convergence. Methods:We study the evolution of the magnetic field in a plane-parallel Cartesian geometry. We discretise the induction equation using a finite difference scheme and then integrate it via the Euler forward method. Two different approaches are used for the integration of the advective terms appearing in the equation: a Forward Time and Central in Space (FTCS) and an Upwind scheme. We compare them in terms of accuracy and performance. We explore the impact of the Upwind method on convergence according to the ratio of planar to vertical field and the Hall parameter. Results:In the limit of a low strength planar field the use of an Upwind scheme provides a vast improvement leading to the convergence of simulations where the Hall parameter is 2 orders of magnitude higher than that of the FTCS. Upwind is still better if the planar field is stronger, yet, the difference of the maximum value of the Hall parameter reached is within a factor of 10 or a few. Moreover, we notice if the schemes diverge their behaviour is very different, with FTCS producing infinite energy, while the Upwind scheme only temporarily increasing the overall magnetic field energy. Conclusions:Overall, the Upwind scheme enhances the efficiency of the simulations allowing the exploration of environments with higher value of electric conductivity getting us closer than before to realistic environmental conditions of magnetars.

Wear Behaviors of AISI 4145H Drilling Tool Steel under Drilling Fluid Environment Conditions.

4145H steel is a commonly used material for downhole tools. However, up to now the wear behavior of 4145H drilling tool steel under real drilling fluid environment conditions is still not clear. In this work, this was investigated using a modified ASTM B611 rubber ring wet grinding test system, in which six kinds of abrasives (talc, dolomite or fluorite, as well as their mixed abrasive with quartz) with metal hardness-to-abrasive hardness ratios (H/HA) ranging from 0.25 to 6.25 were used in the drilling fluid for experiments. The results show that the H/HA value determined the wear mechanism of 4145H steel. When a single soft abrasive was used (with H/HA higher than 1.3–1.5), polishing was the dominantly observed mechanism. While mixed abrasives were applied, a microcutting mechanism due to the ploughing of hard abrasive particles on the steel surface was also observed. The increase in mass fraction of the soft abrasives has little effect on the wear rate of 4145H steel, but its wear rate will significantly increase as the mass fraction of hard abrasives increases. Therefore, in order to extend the life of drilling tools and reduce downhole accidents, the mass fraction of hard particles in the drilling fluid should be reduced as much as possible.

Modelling the Strength and Fracture Parameters of Dam Gallery Concrete Considering Ambient Temperature and Humidity

Due to the complex structure and stress distribution of dam galleries, cracks often appear during the construction, operation and maintenance periods of dams. This paper proposes a method to determine the real strength and fracture parameters of gallery concrete, considering environmental temperature and humidity. The strength and fracture tests were carried out for gallery concrete at various ages and under different curing temperature and humidity conditions. The influence of curing conditions on the mechanical properties of gallery concrete was quantitatively analyzed. The prediction equations of the strength and fracture parameters of gallery concrete under arbitrary temperature and humidity were established. Based on the measured temperature and humidity data, the real mechanical parameters of gallery concrete were predicted. The research results show that the influence of environmental conditions on mechanical parameters cannot be neglected, as this can result in a strength reduction of up to 33.81%. The proposed equations can be used to predict the mechanical parameters of gallery concrete, subject to real environmental conditions, which can help to correct a maximum deviation of 54.62% on parameters calculated using actual ages. The proposed method can provide a scientific basis for the cracking risk analysis and safety assessment of the gallery structure under actual conditions.

Exploring Late Pleistocene hominin dispersals, coexistence and extinction with agent-based multi-factor models

Toward the end of the Pleistocene, archaic humans in Eurasia such as the Neanderthals and Denisovans were completely replaced by anatomically modern humans dispersing from Africa. The causes underlying the replacement and extinction processes remain controversial, especially regarding the relative importance of random events, and anthropogenic and environmental factors. Here, we use the most comprehensive agent-based modeling framework to date for exploring Late Pleistocene human population dynamics under realistic time-evolving environmental conditions. Model simulations suggest multiple out-of-Africa dispersals. Most of these resulted in only partial replacement of Eurasians and long-term coexistence of spatially structured archaic and modern populations in Eurasia. Moreover, a comparison of empirical and model data suggests that the best-documented extinction process – that of the Neanderthals – did not have a single overarching cause, but spatially and temporally diverse causes and mechanisms, such as environmental fluctuations, and asymmetry in resource exploitation efficiency and reproductive rates. When viewed in isolation, various population properties have central importance for replacements, but their true importance can only be understood in comparison and with interactions with other properties.

Understanding the bioaccumulation of pharmaceutical active compounds by clams Ruditapes decussatus exposed to a UWWTP discharge

Twenty-four pharmaceutical active compounds (PhACs) were evaluated in the soft tissues of clams Ruditappes decussatus exposed along a 1.5-km dispersal gradient of the treated effluent from an urban wastewater treatment plant discharging in Ria Formosa, and compared with those in the marine waters and discharged effluents. The clams were exposed for 1 month, in June–July 2016, 2017 and 2018. PhACs were quantified by high performance liquid chromatography coupled to tandem mass spectrometry after the quick, easy, cheap, effective, rugged and safe (QuEChERS) method (clams) or solid-phase extraction (water samples). The most representative PhACs in the effluents and receiving waters (regardless of the tidal dilution effect) were diclofenac, carbamazepine and caffeine (on average ≤ 2 μg/L) and only caffeine exhibited significant inter-annual differences, with higher values in 2017. In turn, the most bioaccumulated PhACs in clams were caffeine (0.54–27 ng/g wet weight, significantly higher in 2016) and acetaminophen (0.37–3.7 ng/g wet weight, significant lower in 2016). A multivariate principal component analysis showed (i) PhAC bioaccumulation primarily depended on biotic factors (clams length and weight), (ii) PhAC physicochemical properties Log Kow, pKa and water solubility interplaying with water abiotic variables were more relevant for explaining data variability in water than the physical dilution/tidal mixing, (iii) this process, reflected by the salinity gradient, had a tertiary role in data variation, responsible for spatial discrimination of marine waters. This study provides a better understanding of PhACs bioaccumulation by clams Ruditapes decussatus in real environmental conditions, under the influence of urban treated effluent dispersal in Ria Formosa coastal lagoon, a major producer of bivalves, ultimately disentangling key factors of PhAC bioaccumulation.

Augmented Reality and Mixed Reality Measurement Under Different Environments: A Survey on Head-Mounted Devices

Augmented Reality (AR) and Mixed Reality (MR) have been two of the most explosive research topics in the last few years. Head-Mounted Devices (HMDs) are essential intermediums for using AR and MR technology, playing an important role in the research progress in these two areas. Behavioral research with users is one way of evaluating the technical progress and effectiveness of HMDs. In addition, AR and MR technology is dependent upon virtual interactions with the real environment. Thus, conditions in real environments can be a significant factor for AR and MR measurements with users. In this paper, we survey 87 environmental-related HMD papers with measurements from users, spanning over 32 years. We provide a thorough review of AR- and MR-related user experiments with HMDs under different environmental factors. Then, we summarize trends in this literature over time using a new classification method with four environmental factors, the presence or absence of user feedback in behavioral experiments, and ten main categories to subdivide these papers (e.g., domain and method of user assessment). We also categorize characteristics of the behavioral experiments, showing similarities and differences among papers.

Research needs targeting direct air capture of carbon dioxide: Material & process performance characteristics under realistic environmental conditions

Research needs targeting direct air capture of carbon dioxide: Material & process performance characteristics under realistic environmental conditions

Algal bioaccumulation and toxicity of platinum are increased in the presence of humic acids

Environmental context The growth in demand for platinum has led to an increase in the presence of this metal in the environment but little is known about its toxicity to aquatic organisms. The presence of organic matter should contribute to decreasing metal bioavailability but the opposite was found for platinum. How ubiquitous natural organic matter can alter the accumulation and effects of platinum group elements remains to be fully elucidated. Rationale There is a growing interest for platinum in ecotoxicology, mainly because of its use in automobile exhaust catalysts. When it reaches aquatic ecosystems, platinum can interact with ligands such as natural organic matter. According to the Biotic Ligand Model, the formation of such complexes should reduce metal bioavailability. As a consequence, toxicity should decrease in the presence of organic matter. Methodology This study focused on the uptake of platinum by two microalgae species (Chlorella fusca and Chlamydomonas reinhardtii) and its subsequent inhibitory effects on growth (96 h). Cells were exposed to platinum (5–300 µg L−1) at three concentrations (0, 10 and 20 mg C L−1) of standard Suwannee River humic acid (SRHA). Platinum bound to humic acid was determined experimentally using partial ultrafiltration to relate metal uptake and toxicity to speciation. Results Unexpectedly, results show that platinum toxicity, expressed as ultrafiltrable Pt (not bound to humic acid) and total Pt concentrations, is enhanced in the presence of humic acid for both algae. For C. fusca, the half maximal effective concentration (EC50) values decreased from 93 to 37 and 35 µg L−1 of ultrafiltrable Pt in the presence of 10 and 20 mg C L−1 SRHA and from 89 to 36 and 0.31 µg L−1 for C. reinhardtii. Discussion In contradiction with the Biotic Ligand Model, the results show that the presence of SRHA can significantly and importantly increase platinum uptake and toxicity as determined in two unicellular green algae, C. reinhardtii and C. fusca. The present work raises the issue of the impact of platinum on microalgae under realistic environmental conditions (ubiquitous presence of organic matter), primary producers being of great ecological importance.

A numerical study of rock bed seasonal thermal storage used for mine ventilation

Global warming and limited fossil resources are two major challenges of the world in the coming years. Many efforts have been devoted in recent years to reduce the dependence on these conventional resources. Mine ventilation is a high energy-consuming activity that could be modified using natural capacities. Rocks are the byproducts of mineral activities which usually are dispersed near the mines. These rocks could be stored in a large hole to be used for thermal energy storage. Rocks are cooled or warmed in parts of a year and their energy will be used in the next months. In this paper, an underground rock bed thermal storage is studied numerically considering real environmental conditions. Effects of different parameters including inlet velocity, reservoir length, rocks average diameter, and rocks thermal properties (different rocks including marble, slag, quarzitic sandstone, and diorite) on the pressure drop and outlet temperature are studied. Results show that low inlet velocities are appropriate for longer usage. For example, the outlet temperature of the reservoir charged in temperature 20 ˚C, used continuously for three months in summer, reaches about 26 ˚C at the end of discharge. Also, deeper reservoirs are suitable for longer discharge time.

A Linear Hybrid Concentrated Photovoltaic Solar Collector: A Methodology Proposal of Optical and Thermal Analysis

The photovoltaic cell surface in linear hybrid concentrated solar collectors receives non-uniform radiative flux, causing additional thermal stress due to hot spots and reducing its electrical performance and durability. The current study proposes a parametric methodology to determine the optimal receiver displacement required in a linear Cassegrain-type hybrid solar collector. The aim was to achieve a minimal non-uniformity distribution and a high radiative flux over the photovoltaic cells, considering optical errors close to real environment conditions and analyzing the heat transfer to determine the electrical and thermal efficiencies. The developed methodology was applied to analyze a case study with a receiver width of 0.125 m and rim angle of 80° and using a commercial silicon photovoltaic cell that supports up to 7000 W/m2. After applying the methodology, a hybrid solar collector with a concentration ratio of 13.0 and receiver displacement of 0.14 m is recommended. As a result, 5728 W/m2 of average radiative flux with non-uniformity lower than 4% was achieved. Thus, thanks to the proposed configuration, a low non-uniformity and high radiative flux were achieved, benefiting the photovoltaic cells’ life while improving their operation.

Numerical study on adhesively bonded glass‐metal facade elements under different loading scenarios

Several research studies have been completed in the past fifteen years on glass panes adhesively bonded to a metal framing with the aim to enhance the structural potential of the material glass in building envelopes. However, the transfer of the obtained results into prototypes or real projects was often impeded either (i) by the degrading properties of the investigated adhesives under the real environmental conditions which facades are subjected to or (ii) because of the limited strength of the investigated silicone adhesives. This contribution presents selected results from a research project dealing with two configurations for glass‐metal facade elements with composite structural behaviour. In the case of the first configuration, which is more suitable for application in real projects due to the applied connection materials, a silicone adhesive bonding along the perimeter of the glass pane together with grouting blocks near the glass pane corners ensure the stress transfer between glass panes and framing. For the second configuration, the stress transfer is obtained solely by acrylic adhesive bonding along the perimeter of the glass pane. In this contribution, results from finite element simulations for the two configurations under different loading scenarios and levels are presented in order to point out the deformation behaviour of such elements, their structural potential as well as some of their limitations. The applied finite element model was previously validated based on experimental results. Load scenarios resulting from in‐plane and out‐of‐plane load situations as well as from temperature loads are covered by the discussed results.

Hierarchical TiO2 Layers Prepared by Plasma Jets.

Heterogeneous photocatalysis of TiO2 is one of the most efficient advanced oxidation processes for water and air purification. Here, we prepared hierarchical TiO2 layers (Spikelets) by hollow-cathode discharge sputtering and tested their photocatalytic performance in the abatement of inorganic (NO, NO2) and organic (4-chlorophenol) pollutant dispersed in air and water, respectively. The structural-textural properties of the photocatalysts were determined via variety of physico-chemical techniques (XRD, Raman spectroscopy, SEM, FE-SEM. DF-TEM, EDAX and DC measurements). The photocatalysis was carried out under conditions similar to real environment conditions. Although the abatement of NO and NO2 was comparable with that of industrial benchmark Aeroxide® TiO2 P25, the formation of harmful nitrous acid (HONO) product on the Spikelet TiO2 layers was suppressed. Similarly, in the decontamination of water by organics, the mineralization of 4-chlorophenol on Spikelet layers was interestingly the same, although their reaction rate constant was three-times lower. The possible explanation may be the more than half-magnitude order higher external quantum efficacy (EQE) compared to that of the reference TiO2 P25 layer. Therefore, such favorable kinetics and reaction selectivity, together with feasible scale-up, make the hierarchical TiO2 layers very promising photocatalyst which can be used for environmental remediation.

Reliability Analysis of Wireless Sensor Network for Smart Farming Applications.

Wireless Sensor Networks are subjected to some design constraints (e.g., processing capability, storage memory, energy consumption, fixed deployment, etc.) and to outdoor harsh conditions that deeply affect the network reliability. The aim of this work is to provide a deeper understanding about the way redundancy and node deployment affect the network reliability. In more detail, the paper analyzes the design and implementation of a wireless sensor network for low-power and low-cost applications and calculates its reliability considering the real environmental conditions and the real arrangement of the nodes deployed in the field. The reliability of the system has been evaluated by looking for both hardware failures and communication errors. A reliability prediction based on different handbooks has been carried out to estimate the failure rate of the nodes self-designed and self-developed to be used under harsh environments. Then, using the Fault Tree Analysis the real deployment of the nodes is taken into account considering the Wi-Fi coverage area and the possible communication link between nearby nodes. The findings show how different node arrangements provide significantly different reliability. The positioning is therefore essential in order to obtain maximum performance from a Wireless sensor network.

Quantitative prediction of dynamic HTO migration behavior in the soil and non-negligible evapotranspiration effect

Tritium is mainly produced from nuclear facilities apart from nuclear tests. After being released to the environment, tritium would cause water & food contamination due to its radioactivity and mobility. This study investigated dynamic characteristics of tritiated water (HTO) migration in the soil and evapotranspiration effect based on realistic environmental conditions. The influences of soil types and time-varying environmental factors such as precipitation and evapotranspiration on tritium migration behaviors were specially discussed under normal continuous and accidental short-term release conditions. Radiation dose caused by dynamic tritium evapotranspiration was evaluated. The results show that tritium migration velocity in the soil is much higher than other particles such as cesium due to negligible adsorption of tritium by the soil. Tritium migration in the soil from up to down is attributed to precipitation. On the contrary, evapotranspiration factor would carry tritium movement along the opposite direction. A considerable fraction approximately 55% of tritium deposited in the soil would be reemitted into the air from bare soil and plant leaves due to evapotranspiration effect. Subsequently, the radiation dose caused by second plume due to evapotranspiration effect might be higher than the first plume due to direct release from the nuclear facility under routine discharge.