Combined Effects Of Environmental Conditions Research Articles

Energy-Aware Camera Location Search Algorithm for Increasing Precision of Observation in Automated Manufacturing

Visual servoing technology is well developed and applied in many automated manufacturing tasks, especially in tools’ pose alignment. To access a full global view of tools, most applications adopt an eye-to-hand configuration or an eye-to-hand/eye-in-hand cooperation configuration in an automated manufacturing environment. Most research papers mainly put efforts into developing control and observation architectures in various scenarios, but few have discussed the importance of the camera’s location in the eye-to-hand configuration. In a manufacturing environment, the quality of camera estimations may vary significantly from one observation location to another, as the combined effects of environmental conditions result in different noise levels of a single image shot in different locations. In this paper, we propose an algorithm for the camera’s moving policy so that it explores the camera workspace and searches for the optimal location where the image’s noise level is minimized. Also, this algorithm ensures the camera ends up at a suboptimal (if the optimal one is unreachable) location among the locations already searched with the limited energy available for moving the camera. Unlike a simple brute-force approach, the algorithm enables the camera to explore space more efficiently by adapting the search policy by learning the environment. With the aid of an image-averaging technique, this algorithm, in the use of a solo camera, achieves observation accuracy in eye-to-hand configurations to a desirable extent without filtering out high-frequency information in the original image. An automated manufacturing application was simulated, and the results show the success of this algorithm’s improvement in observation precision with limited energy.

Effect of UV irradiation on PV modules and their simulation in newly designed site-specific accelerated ageing tests

One of the significant environmental stress factors for degradation in the PV module is UV irradiation exposure in the field during its operational lifespan. In this work, degradation analysis of 20-years field-operated PV modules have been performed. The defects that occurred in those modules are due to the combined effect of environmental conditions like temperature, humidity, soiling, etc., along with UV irradiation. Based on the literature resources, efforts have been made to analyze the role of UV irradiation on the degradations that happened during 20 years of field operation of the PV modules. Average Pmax, Isc and Voc degradation are found to be 1.49 %/ year, 0.59 %/year and 0.29 %/year after 20 years of exposure, respectively. The effect of UV irradiation and temperature in indoor conditions has been analyzed for the 20 years of field-exposed PV modules. The effect of browning in the module is also studied in this research work at the cell level. Since the UV irradiation doses mentioned in IEC 61215 are not sufficient as compared to the amount of UV irradiation faced by the PV modules throughout their lifetime, therefore, a procedure is proposed to estimate the UV irradiation doses for different climatic conditions. The UV radiation data for India's climatic zones have been estimated and analyzed, to design accelerated UV stress test conditions using the procedure reported in this paper. The accelerated testing time equivalent for five years of UV irradiations on PV modules in the field is proposed to be around 40 days.

Scales and Historical Evolution: Methods to Reveal the Relationships between Ecosystem Service Bundles and Socio-Ecological Drivers-A Case Study of Dalian City, China.

Ecosystem service (ES) bundles can be defined as the temporal and spatial co-occurrence of ESs. ES bundles are jointly driven by socio-ecological factors and form at different scales. However, in recent research, a few studies have analyzed the dynamic evolution and driving mechanisms of ES bundles at different scales. Therefore, this study explored the spatial patterns of six ESs supplied in Dalian (China) from 2005 to 2015 at three spatial scales, determining the distribution and evolution patterns of ES bundles and their responses to socio-ecological driving factors. Our results are as follows: (1) We identified four ES bundles representing ecological conservation, water conservation, ecological depletion, and food supply. The developmental trajectory of each ES bundle could be attributed to the combined effects of environmental conditions and urban expansion. In particular, the water conservation bundle and food supply bundle were changed to the ecological depletion bundle. Given the ongoing urbanization, the conflict between ESs has intensified. (2) The impact of socio-ecological driving factors on ES bundles vary with scale. At three spatial scales, the digital elevation model (DEM) and normalized difference vegetation index (NDVI) had a great impact on ES bundles. Urbanization indicators also strongly explain the spatial distribution of ES bundles at the county and grid scales. The interaction factor detector shows that there is no combination of mutual weakening, indicating that the formation of ES bundles is driven by multiple factors in Dalian. Overall, this study used a more holistic approach to manage the ecosystem by studying the temporal-spatial dynamics of the multiple ESs.

Experimental and finite element analysis of the long-term behaviour of GFRP-concrete hybrid beams fabricated using adhesive bonding

This paper presents experimental and numerical investigations about the short- and long-term behaviour of a hybrid beam consisting of a GFRP pultruded profile bonded by an epoxy adhesive joint to a reinforced concrete slab. The experimental program included flexural creep tests on GFRP I-profiles and on hybrid beams subjected to constant loads. The deflections and the longitudinal strains were measured in natural environmental conditions and recorded for time durations up to 3500 h. Also, three-dimensional models, based on the incremental form of the linear viscoelastic theory, were proposed to study the evolution of strains and stresses over time for the structures. The results of the sustained-load test show that creep deflections on the order of 27–37% of the initial static deflections were observed for the hybrid beams after about 5 months of loading. It is also found that, for the hybrid beam, the rapid degradation of bond strength, resulted from the combined effect of environmental conditions and applied loading, leads to debonding and subsequently a brutal failure. Furthermore, the finite-element analysis is found to be able to simulate the long-term behaviour of the hybrid beam and help understand the complex changes in the stress state that occur over time.

Effect of Pavement Surface Aging on Tire-Pavement Noise: A Case Study in the State of Qatar

The acoustical performance of asphalt pavements changes with time due to combined effects of environmental conditions and various distresses induced by repeated and heavy traffic. This study examined the changes in the acoustical performance of dense graded asphalt (DGA) pavements over time in the State of Qatar. Tire-pavement noise was measured using on board sound intensity (OBSI) method. The OBSI noise measurements were conducted on DGA pavements with different age and the results were analyzed to evaluate the effect of aging on tire-pavement noise. The results demonstrated that the tire-pavement noise increased with pavement age. The frequency analysis of three road segments showed that at early stage of pavement service life, the noise level is more affected at higher frequency due to the densification and increased air pumping mechanism. At later stage of pavement service life, the noise level is more affected at lower frequency due to the change in pavement surface conditions (e.g., cracking and raveling).

An interaction model for the combined effect of temperature, pH and water activity on the growth rate of E. coli K12

Previous research has indicated that more complex model structures than the commonly used gamma model are needed to obtain an accurate prediction of the effect of multiple environmental conditions on the microbial growth rate. Due to the complexity associated with the development of such model structures, it is recommended that the model structure is compatible with a modular model building method.In this research, a gamma-interaction model was built to describe the combined effect of temperature, pH and water activity on the microbial growth rate of E. coli K12 based on a dataset of 68 bioreactor experiments. This novel interaction model was compared with the standard gamma model. The model structures were tested separately for the combined effects of (i) temperature and pH, (ii) pH and water activity, (iii) temperature and water activity and (iv) temperature, pH and water activity.Based on the results of this research, it was concluded that models for the combined effect of environmental conditions need to allow for sufficient flexibility for the description of combined effects of environmental conditions to obtain accurate model predictions. In the current study, this flexibility was successfully introduced by using the gamma-interaction model. A cross-validation study also demonstrated that the predictions of the interaction model are more robust with respect to the specific data used than the gamma model. As such, the gamma-interaction model provides food producers and food safety authorities with a more accurate and reliable tool for the prediction of the microbial growth rate as a function of multiple environmental conditions.

Influence of temperature on phenanthrene toxicity towards nitrifying bacteria in three soils with different properties

This study focused on the combined effect of environmental conditions (temperature) and contamination (polycyclic aromatic hydrocarbons, PAHs) on the activity of soil microorganisms (nitrifying bacteria). Phenanthrene (Phe) at five contamination levels (0, 1, 10, 100 and 1000 mg kg−1 dry mass of soil) was employed as a model PAH compound in laboratory experiments that were conducted at three temperatures (i.e., 20 °C (recommended by ISO 15685 method), 15 and 30 °C). Three soils with different properties were used in these studies, and the activity of the nitrifying bacteria was assessed based on nitrification potential (NP) determinations. For the statistical evaluation of the results, the ANCOVA (analysis of covariance) method for three independent variables (i.e., temperature, phenanthrene concentration, soil matrix (as a qualitative variable)) and their interactions was employed. The results indicated on the significant interaction of all studied factors. Temperature influenced the toxicity of Phe towards NP, and this effect was related to the Phe concentration as well as was varied for the different soils. A low content of soil organic matter (controlling bioavailability of phenanthrene to soil microorganisms) enhanced the combined effect of temperature and Phe toxicity, and a high biological activity of the soil (high NP values) increased the effect of high temperature on the Phe stimulatory influence. The results indicate that the temperature should not be neglected in tests evaluating PAH ecotoxicity, especially for reliable ecological risk assessment.

Experimental Investigation for Tensile Performance of GFRP-Steel Hybridized Rebar

Tensile performance of the recently developed “FRP Hybrid Bar” at Korea Institute of Civil Engineering and Building Technology (KICT) is experimentally evaluated by the authors. FRP Hybrid Bar is introduced to overcome the low elastic modulus of the existing GFRP bars to be used as a structural member in reinforced concrete structures. The concept of material hybridization is applied to increase elastic modulus of GFRP bars by using steel. This hybridized GFRP bar can be used in concrete structures as a flexural reinforcement with a sufficient level of elastic modulus. In order to verify the effect of material hybridization on tensile properties, tensile tests are conducted. The test results for both FRP Hybrid Bar and the existing GFRP bars are compared. The results indicate that the elastic modulus of FRP Hybrid Bar can be enhanced by up to approximately 250 percent by the material hybridization with a sufficient tensile strength. To ensure the long-term durability of FRP Hybrid Bar to corrosion resistance, the individual and combined effects of environmental conditions on FRP Hybrid Bar itself as well as on the interface between rebar and concrete are currently under investigation.

Seismic damage evaluation of historical structures during Van earthquake, October 23, 2011

Seismic risk assessment of historical structures (mosques, churches, monuments, towers, palaces, aqua structures, etc.) has attracted many researchers' attention for the last few decades. This paper aims at investigating the damage at two historical structures, which partially collapsed during the main shock of the October 23, 2015, Van earthquake in eastern Turkey. The massive rigid body of both structures survived the earthquake without any damage, but the Narthexes of both structures collapsed. A thorough examination of the existing guidelines (ASCE 41, 2006; EC8-3, 2005 and PERPETUATE, 2010) are first studied. Response spectrum analyses are then performed to evaluate the seismic performance of the structures. The results of the numerical analyses revealed the fact that the collapse of the Narthexes could not be identified by the response spectrum analysis in which a sticked mode is assumed between both components. The failures of both structures were possibly due to local effects such as; independent responses of the Narthexes with respect to the main structure and/or weakened column-arch joints due to combined effects of environmental conditions and human interventions.

Family, environment and silviculture effects in pure- and mixed-family stands of loblolly (Pinus taeda L.) and slash (P. elliottii Engelm. var. elliotttii) pine

Few studies have quantified the combined effects of environmental conditions, the planting of elite full-sib pine families, intra-specific competition, and intensive silvicultural treatment on unit area production of loblolly pine and slash pine. This study examined these factors at age 2 and 10years for factorial experiments in the Western Gulf (WG) area of the southeastern United States. The experiments consisted of seven pine families (five elite and one poor full-sib loblolly pine families, one elite full-sib slash pine family), two silvicultural intensities (high and low intensity), and three sites. Two deployment methods (mixed and pure-family plots) were used to examine crop and competition ideotypes from among the loblolly families deployed. Family and site were significant main effects at both ages for both individual tree (diameter, height) and stand growth (basal area, volume), and culture was only significant at age 2years. Significant interactions of culture×site and family×site for different growth metrics indicated varying cultural treatment and family performance effects at the different sites, but family response was consistent across cultural treatments. At age 2 and 10years, the deployment main effect was significant for tree height, and for stand basal area and volume. A deployment×site×family interaction for DBH identified a competition ideotype (fast grower) and crop ideotype (slow grower) at the better overall site. The competition ideotype that performed best was not from the WG region, while the slash pine families performed poorly and suffered high levels of storm damage. For loblolly pine, wind damage was the most severe for the plots with low silvicultural intensity. Overall, these results suggested that high performing loblolly pine families do well under a variety of conditions in the WG region and that the competition ideotype and stand uniformity may result in less mortality and greater resistance to wind damage.

Enhancement in Elastic Modulus of GFRP Bars by Material Hybridization

Fiber reinforced polymer (FRP) reinforcing bars for concrete structure has been extensively investigated for last two decades and a number of FRP bars are commercially available. However, one of shortcomings of the existing FRP bars is its low elastic modulus, if glass fibers are used (i.e., GFRP). The main objective of this study using the concept of material hybridization is to develop a viable hybrid FRP bar for concrete structures, especially for marine and port con- crete structures. The purposes of hybridization are to increase the elastic modulus of GFRP bar with acceptable tensile strength. Two types of hybrid GFRP bar were considered in the development: GFRP crust with steel core and GFRP bar with steel wires dispersed over the cross-section. Using E-glass fibers and unsaturated polyester resins, the hybrid GFRP bar samples of 13 mm in diameter were pultruded and tested for tensile properties. The effect of hybridization on tensile properties of GFRP bars was evaluated by comparing the results of tensile test with those of non-hybrid GFRP bars. The results of this study indicated that the elastic modulus of the hybrid GFRP bar was increased by up to 270 percent by the material hybridization. The results of the test and the future recommendations are summarized in this paper. To ensure long-term durability of the hybrid GFRP bars in waterfront structure applications, the individual and combined effects of environmental conditions on hybrid GFRP rebar itself as well as on the interface between rebar and concrete should be accessed.

Effects of Self-Fertilization, Environmental Stress and Exposure to Xenobiotics on Fitness-Related Traits of the Freshwater Snail Lymnaea stagnalis

Genetic and ecological factors may interact in their effects on fitness. Such interactions are thus to be expected between inbreeding and exposure of a population to a toxicant. The magnitude of inbreeding depression is thought to increase in stressful environments. To test this hypothesis, we investigated the combined effects of environmental conditions and inbreeding on fitness in the self-fertile snail Lymnaea stagnalis, using a stress gradient (0-2) applied to a 100 isolated and paired lineages: laboratory control (0), outdoor microcosm control (1) and pesticide exposure under outdoor microcosm conditions (2). Outdoor stress conditions were maintained for 28 days prior to measurements of fitness traits (fecundity, hatching success, and size at hatching) under laboratory conditions, so that delayed environmental effects could be estimated. Under laboratory control conditions, we found significant initial family level heterogeneity for most measured traits, including physiological performances as assessed through energetic biomarkers. Whatever the environmental conditions, inbreeding depression was very low for progeny performances. Negative values of self-fertilization depression (SFD) were obtained. Unexpectedly, SFD showed a negative relationship with the assumed stress intensity, reflecting a higher sensitivity under pairing than under selfing, mostly due to parental fecundity. This suggests that stressful conditions may favour selfing. Stress intensity increased the distribution limits of both depression indices, suggesting that changes in fitness are less predictable in a population under stress. Implications of such findings for environmental risk assessment of pesticides are discussed.

Lipolysis of pork fat by the meat starter culture Debaryomyces hansenii at various environmental conditions.

Lipolysis of pork fat by the meat starter culture Debaryomyces hansenii added at a level of 3.5 x 10(6) cells/ml was investigated at different temperatures (10-30 degrees C), pH values (4.7-6.0). NaCl concentrations (2.5-7.5% w/v), and times of incubation (5-15 days). Pronounced growth was obtained amounting to 10(7)-10(9) cells/ml even at conditions combining the lowest temperature, the lowest pH and the highest NaCl concentration. Pork fat was hydrolysed to an extent depending on the environmental conditions. A quadratic polynomial model was developed describing the combined effects of environmental conditions on lipolysis. Regression analysis of data indicated that temperature, pH and time of incubation at conditions of meat fermentation were all significant factors in controlling lipolysis whereas NaCl concentration at the levels studied had no significant effect. Lipolysis increased when temperature increased. At 10 degrees C, lipolysis was very restricted even though growth was observed. An increase in pH resulted in higher lipolysis, the effect being most pronounced at high temperatures.

The combined effects of environmental conditions on lipolysis of pork fat by lipases of the meat starter culture organisms Staphylococcus xylosus and Debaryomyces hansenii

The effects of environmental conditions on lipolysis by cell-free extracts from the meat starter culture organisms Staphylococcus xylosus and Debaryomyces hansenii were studied using pork fat emulsions as model systems. For the individual effects of temperature and pH it was found that the optimal conditions for the lipolysis by S. xylosus lipase were 37 °C and pH 7.0, and 37 °C and pH 6.5 for the lipolysis by D. hansenii lipase. For the combined effects of conditions relevant to meat fermentation i.e. 10–30 °C, pH 4.7–6.0, 2.5–7.5% ( w v ) NaCl and incubation times of 2–6 days, the empirical models indicated that temperature, pH and incubation time had important effects on total lipolysis whereas NaCl concentration had little effect. For both cultures lipolysis was strongly inhibited at conditions of meat fermentation compared to optimal conditions. For any set of the conditions which were examined the total lipolysis caused by D. hansenii lipase was lower than that caused by S. xylosus lipase.

Ageing of organic electrical insulating materials due to radiation: Physical properties of a cycloaliphatic epoxy resin irradiated under vacuum

Physical properties of a cycloaliphatic epoxy resin irradiated under vacuum have been investigated. In particular dynamic-mechanical, dielectric and tensile measurements have been performed. This is a useful basis with a view to studying the ageing phenomenon of organic insulating materials due to radiation under the combined effect of environmental conditions. The results indicate that, in the dose range investigated (0-1.5 x 10 6Gy), the main effect of γ-rays under vacuum is to increase the degree of crosslinking