Construction Of Artificial Structures Research Articles

Assessing and Optimizing Ecological Flow Rates for the Habitat of Zacco platypus in the Tan River

As rivers face growing environmental challenges due to climate change and the construction of artificial structures, it is essential that we improve river ecosystems to maintain their ecological functions and preserve the health of aquatic habitats. The aim of this study was to assess the aquatic ecosystem health of the lower reaches of the Tan River. We employed the Physical Habitat Simulation System and Hydrologic Engineering Center’s River Analysis System to calculate the ecological flow rate based on the weighted usable area (WUA) of Zacco platypus, which is a representative fish species in the Tan River, and the flow rate relationship curves. By analyzing the flow rates in the Tan River across different seasons from 2012 to 2021, we determined that the seasonal optimal ecological flow rate was 10.21–10.27 m3/s. Meanwhile, the WUAs for spring, summer, and autumn and winter were 90–100%, 95–100%, and 75–100%, respectively. Despite meeting the ecological flow criteria for summer, fall, and winter over 50% of the time, spring fell short at 41%; hence, the Tan River flow rates should be secured particularly in spring. This study highlights the urgency of addressing seasonal variations to ensure the overall health of the Tan River ecosystem.

Additive manufactured thermal metamaterial devices for manipulating heat flow: geometric configuration design and SLM-assisted fabrication

Thermal metamaterials, benefitting from ingenious design and construction of artificial structures, commonly exhibit amazing heat conduction characteristics beyond naturally occurring materials in conventional scenarios. Based on the transformation thermodynamics theory and the effective medium theory, two types of metamaterial structure devices aiming to manipulate heat flow were artificially designed and fabricated with the aid of selective laser melting additive manufacturing technology in this work. The well-designed thermal metamaterial structures respectively achieved the thermal self-focus and thermal torsion functions. The relation of the configuration geometric parameters and the heat flux changes of the thermal metamaterial devices was carefully dissected. Following the geometric optimization design, the heat transfer directions achieved to be precisely manipulated as the design wishes. The changes in both heat flux and temperature distribution on the thermal self-focus and thermal torsion devices were traced through the numerical simulation and experimental measurement methods. The thermal simulation results were highly consistent with the experimental findings of the design-intended manipulation effects on the heat flow. The research work verified the applicability of the thermal metamaterial structures fabricated with the assist of selective laser melting in the thermal engineering fields.

Making seawalls multifunctional: The positive effects of seeded bivalves and habitat structure on species diversity and filtration rates

The marine environment is being increasingly modified by the construction of artificial structures, the impacts of which may be mitigated through eco-engineering. To date, eco-engineering has predominantly aimed to increase biodiversity, but enhancing other ecological functions is arguably of equal importance for artificial structures. Here, we manipulated complexity through habitat structure (flat, and 2.5 cm, 5 cm deep vertical and 5 cm deep horizontal crevices) and seeding with the native oyster (Saccostrea glomerata, unseeded and seeded) on concrete tiles (0.25 m × 0.25 m) affixed to seawalls to investigate whether complexity (both orientation and depth of crevices) influences particle removal rates by suspension feeders and colonisation by different functional groups, and whether there are any ecological trade-offs between these functions. After 12 months, complex seeded tiles generally supported a greater abundance of suspension feeding taxa and had higher particle removal rates than flat tiles or unseeded tiles. The richness and diversity of taxa also increased with complexity. The effect of seeding was, however, generally weaker on tiles with complex habitat structure. However, the orientation of habitat complexity and the depth of the crevices did not influence particle removal rates or colonising taxa. Colonisation by non-native taxa was low compared to total taxa richness. We did not detect negative ecological trade-offs between increased particle removal rates and diversity and abundance of key functional groups. Our results suggest that the addition of complexity to marine artificial structures could potentially be used to enhance both biodiversity and particle removal rates. Consequently, complexity should be incorporated into future eco-engineering projects to provide a range of ecological functions in urbanised estuaries.

Real‐Time Visual Monitoring of Kinetically Controlled Self‐Assembly

AbstractThe construction of artificial structures through hierarchical self‐assembly based on noncovalent interactions, as well as monitoring during the self‐assembly process, are important aspects of dynamic supramolecular chemistry. Herein we describe the complex dynamics of chiral N,N′‐diphenyl dihydrodibenzo[a,c]phenazine derivatives (S)/(R)‐DPAC, whose different assemblies were found to have distinct optical and morphological characteristics. With ratiometric fluorescence originating from vibration‐induced emission (VIE), the self‐assembly process from kinetic traps to the thermodynamic equilibrium state could be monitored in real time by optical spectrometry. During the morphology transformation from particles to nanobricks, strong circularly polarized luminescence was induced with glum=1.6×10−2. The excited‐state characteristics of the self‐assemblies enabled investigation of the relationship between molecular aggregation and conformational change, thus allowing effective monitoring of the sophisticated supramolecular self‐assembly process.

Real-Time Visual Monitoring of Kinetically Controlled Self-Assembly.

The construction of artificial structures through hierarchical self-assembly based on noncovalent interactions, as well as monitoring during the self-assembly process, are important aspects of dynamic supramolecular chemistry. Herein we describe the complex dynamics of chiral N,N'-diphenyl dihydrodibenzo[a,c]phenazine derivatives (S)/(R)-DPAC, whose different assemblies were found to have distinct optical and morphological characteristics. With ratiometric fluorescence originating from vibration-induced emission (VIE), the self-assembly process from kinetic traps to the thermodynamic equilibrium state could be monitored in real time by optical spectrometry. During the morphology transformation from particles to nanobricks, strong circularly polarized luminescence was induced with glum =1.6×10-2 . The excited-state characteristics of the self-assemblies enabled investigation of the relationship between molecular aggregation and conformational change, thus allowing effective monitoring of the sophisticated supramolecular self-assembly process.

Evaluation of Coastal Sediment budget on Bongpo Beach by Structure installation

The coastal areas of South Korea are experiencing changes in erosion and sedimentation due to the irregular movements of silt and sediment in rivers and coasts. Erosion is particularly significant on the east coast due to changes in wave characteristics caused by the construction of artificial structures. Coastal erosion can be mitigated by evaluating coastal sediment budget based on long-term changes in wave characteristics and climate and by establishing a clear coastal management system accordingly. We investigated the changes in the movement of sand by waves, by performing an experiment to estimate the amount of sediment movement for Bongpo Beach that has been categorized as “severe” in the coastal erosion status data of the Ministry of Oceans and Fisheries(Ministry of Oceans and Fisheries, 2019). 54 representative waves were generated with input reduction tools. Each representative wave was used as input data for the Delft3d flow model and the SWAN wave model. And the final sedimentation results were calculated by considering the ratio corresponding to each representative wave. Finally, the four submerged breakwater and the one groin, which are currently installed in front of Bongpo, were simulated to analyze the changes in sedimentation before and after the structure.

Interacting effects of habitat structure and seeding with oysters on the intertidal biodiversity of seawalls.

The construction of artificial structures, such as seawalls, is increasing globally, resulting in loss of habitat complexity and native species biodiversity. There is increasing interest in mitigating this biodiversity loss by adding topographic habitat to these structures, and/or seeding them with habitat-forming species. Settlement tile experiments, comparing colonisation of species to more and less complex habitats, have been used to inform eco-engineering interventions prior to their large-scale implementation. Most studies have focused on applying one type of intervention (either adding habitat structure or seeding with native organisms), so it is unclear whether there are greater benefits to biodiversity when multiple interventions are combined. Using a fully orthogonal experiment, we assessed the independent and interactive effects of habitat structure (flat vs. crevice/ridges) and seeding with native oysters (unseeded vs. seeded) on the biodiversity of four different functional groups (sessile and mobile taxa, cryptobenthic and pelagic fishes). Concrete tiles (flat unseeded, flat seeded, complex unseeded and complex seeded) were deployed at two sites in Sydney Harbour and monitored over 12 months, for the survival and colonisation of oysters and the species density and abundances of the four functional groups. The survival of seeded oysters was greater on the complex than flat tiles, at one of the two sites, due to the protective role of crevices. Despite this, after 12 months, the species density of sessile invertebrates and the percentage cover of seeded and colonising oysters did not differ between complex and seeded tiles each of which supported more of these variables than the flat unseeded tiles. In contrast, the species density of mobile invertebrates and cryptobenthic fishes and the MaxN of pelagic fishes, at 1 month, were only positively influenced by seeding with oysters, which provided food as well as habitat. Within the complex seeded and unseeded tiles, there was a greater species density of sessile taxa, survival and percentage cover of oysters in the crevices, which were more humid and darker at month 12, had lower high temperature extremes at months 1 and 12, than on the ridges or flat tiles. Our results suggest that eco-engineering projects which seek to maximise the biodiversity of multiple functional groups on seawalls, should apply a variety of different microhabitats and habitat-forming species, to alter the environmental conditions available to organisms.

Analysis on Sediment Transport System in the East Coast of Korea

Shim, K.T.; Kim, K.H.; Kim, H.D.; and Kwak, K.S., 2020. Analysis on sediment transport system in the East coast of Korea. In: Malvarez, G. and Navas, F. (eds.), Global Coastal Issues of 2020. Journal of Coastal Research, Special Issue No. 95, pp. 643–648. Coconut Creek (Florida), ISSN 0749-0208.In an area comprising a long and a monotonous coastline such as that observed along the east coast of Korea, erosion and accretion can occur repeatedly due to seasonal influences; this leads to the formation of an equilibrium for the sediment budget. However, the construction of artificial structures has caused changes in the sediment budget, which has led to unidirectional sediment transport and excessive erosion and accretion. Recently, there has been an increase in the frequency of appearance of high wave groups that are observed for long periods due to a rise in the sea level and the emerging abnormal climate. This has caused large-scale morphological change and is the major factor that accelerates beach erosion. This study monitors a target area wherein a sediment transport was observed to actively occur; this was achieved by using a beach stabilization measure. The variations in the beach profile and the ratio of the sandy beach budget were predicted using the results obtained. In addition, the sediment transport system of the east coast of Korea was examined through comparison with empirical formulas by classifying the erosive and sedimentary beaches. This study also presents the indicators that will govern the topography of Korea in the future.

Influence of high-frequency cyclic loading on mechanical and structural characteristics of rail steel under extreme conditions

In this paper topical issues of change of a microstructure and microhardness in steel at high-frequency vibration influence which is observed in technological pipelines, connected to the pump and compressor equipment. To study the micro-structures of samples after influence of high-frequency loading, the authors used optical microscopy and microhardness testing. Relevant and timely is the task of modelling and subsequent design and construction of railways, taking into account a wide range of geometric and mechanical characteristics, which is most in demand in the construction of artificial structures in the Arctic, due to the large temperature difference and differences in temperature coefficients of materials. The purpose of this work is to study the mechanical and structural characteristics of 40X steel under high-frequency loading conditions. For mechanical and structural studies the authors prepared the samples from a rod of 40X steel with a diameter of 12 mm. The strength properties of steel was evaluated by tension testing, fatigue testing, then structural analysis (metallographic studies) and microhardness testing.

The composition of coral reefs in Ulee Lheue breakwater, Banda Aceh, Aceh, Indonesia

The present study was aimed to catalog the coral reefs that are found in Ulee Lheue breakwater, and providing a baseline data that will be valuable in Aceh marine conservation plan in the future. The research was conducted from February to October 2015. The station of observations was designed by systematic sampling. The sampling stations were located on the outer side and inner side the breakwater with a station spacing of 250 m. Furthermore, 50 m roll meter was used in each station as the reference to laying squares transects (size 100 × 100 cm) for coral reefs observation. Then, the square transects placed on 0, 5, 10, 15, 20, 25, 30, 35, 40, 45 and 50 m. The results showed the reef at the outer breakwater consists of 11 coral genus of 244 colonies. While on the inner side of the breakwater, eightgenera of 46 colonies were observed. Acropora and Pocillopora were the most common genus on the outer side of the breakwater, while Chypastrea and Porites were the most common on the inner side. 0-5 cm coral colony size was the most common size found on both sides of the breakwater. This result showed that the construction of artificial structures on the coast is not only important in the development of a city but also important for marine biology and ecology study.

Planform Island change assessment for inhabited Lakshadweep Islands

Impacts of coastal processes and anthropogenic activities threaten the archipelago of low-lying reef islands. In this study, long-term (1972–2015) and short-term (2000–2015) shoreline change analyses of ten inhabited Lakshadweep Islands were done using linear regression rates. Of significance, the results highlight that all ten islands are erosional in the long term, with Androth Island being the highest erosional in both the periods, but it shows a stable platform in the short-term periods. More than 50% of the islands indicate shrinkage in planform change in both ocean and lagoon sides of the islands. Construction of artificial structures (seawalls/tetrapods) along the shoreline has helped to reduce the erosion in some localised areas. However, adverse effect of these armoured structures has caused loss of beaches, valuable coastal resources and marine habitats. Although natural reefs protect the lagoon side of island, it is clear that widespread erosion is along both the sides due to anthropogenic activities that are susceptible to the sea-level rise.

Investigation of Coastal Environment Change Using Wave Measurement Sensors and Geographical Laser Scanner

The construction of large-scale coastal structures in any coastal area may not only have direct effects on the coastal environment in that vicinity but also cause severe property damage. In order to prevent this problem, probable effects should be appreciated before any construction and the mechanism that may cause any probable damage must be accurately analyzed along with the plans to minimize damage. This study sought to analyze the cause and mechanism of damage inflicted on coasts by artificial structures through reviewing beach erosions that have occurred on beaches on the east coast of Korea after the large-scale construction of artificial structures, for which wave heights were measured in the vicinity of those structures, and the correlation between the measurements and the analysis data of waves and coastal erosion on the surrounding beach was analyzed. In addition, the correlation between coastal erosion and wave data was applied in order to understand what impact large waves have in relation to sand loss. Accordingly, a movable-bed physical model test was employed to appraise the factors that cause coastal erosion to take place.

The composition of reef-associated fishes in Ulee Lheue breakwater Banda Aceh, Aceh, Indonesia

The tsunami of December 26, 2004, damaged Ulee Lheue Port that located in Meuraxa sub-district of Banda Aceh. In the rebuilding of Ulee Lheue Port, the breakwater with a length of approximately 2 km along the coastline of Ulee Lheue, also constructed. Artificial structure in coastal areas such as the breakwater not only crucial for engineering science but also essential for the biological and ecological study. However, the study of marine biodiversity especially reef fishes in Ulee Lheue breakwater is not available until this study. Hence, the present study was aimed to catalog the reef-associated fishes species in Ulee Lheue breakwater. The research was conducted from February to October 2015. The sampling sites were designed by systematic sampling. Sampling sites were located on the outer side and inner side the breakwater with each station spacing of 250 m. The reef fish data were collected using the Underwater Visual Census in 3 meters depth on each station. There were 87 species of reef fishes found in the Ulee Lheue water. This result showed that the construction of artificial structures on the coast is not only crucial in the development of a city but also significant for marine biology and ecology study.

인공구조물 건설 후 안면도 가경주 간석지의 퇴적환경 및 미지형변화 분석

인공구조물 건설 후 안면도 가경주 간석지의 퇴적환경 및 미지형변화 분석

Increasing habitat complexity on seawalls: Investigating large‐ and small‐scale effects on fish assemblages

The construction of artificial structures in the marine environment is increasing globally. Eco‐engineering aims to mitigate the negative ecological impacts of built infrastructure through designing structures to be multifunctional, benefiting both humans and nature. To date, the focus of eco‐engineering has largely been on benefits for benthic invertebrates and algae. Here, the potential effect of eco‐engineered habitats designed for benthic species on fish was investigated. Eco‐engineered habitats (“flowerpots”) were added to an intertidal seawall in Sydney Harbour, Australia. Responses of fish assemblages to the added habitats were quantified at two spatial scales; large (among seawalls) and small (within a seawall). Data were collected during high tide using cameras attached to the seawall to observe pelagic and benthic fish. At the larger spatial scale, herbivores, planktivores, and invertebrate predators were generally more abundant at the seawall with the added flowerpots, although results were temporally variable. At the smaller spatial scale, certain benthic species were more abundant around flowerpots than at the adjacent control areas of seawall, although there was no general pattern of differences in species density and trophic group abundance of pelagic fish between areas of the seawall with or without added habitats. Although we did not find consistent, statistically significant findings throughout our study, the field of research to improve fish habitat within human‐use constraints is promising and important, although it is in its early stages (it is experimental and requires a lot of trial and error). To advance this field, it is important to document when effects were detected, and when they were not, so that others can refine the designs or scale of habitat enhancements or their study approaches (e.g., sampling protocols).

Features design and construction of artificial structures for Maglev - roads

The article is devoted to the design and construction of artificial structures. Introduction. A brief analysis of foreign experience in the design and construction of bridges and overpasses for roads with magnetic levitation technology (maglev-roads). The basic parameters and design and technology solutions span structures of various sections and pillars. Analysis: Based on international experience, discussed the use of different materials for possible use in the construction of roads, maglev, such as concrete and steel, as well as composite materials. The operation of superstructures of various lengths and systems. The estimation of man-made structures of a continuous system, which can reduce their material consumption due to a more favorable distribution of forces arising in the beams. Results: The possible construction methods magnetic levitation roads, such as the use of scaffolding , moving from a flight to flight as the concreting sections, as well as the method of cyclical longitudinal sliding, which combines the serial production of sections of continuous superstructure on the stocks and longitudinal shifting collected whip of several sections on axis of the bridge. Conclusions: Formulated the main technical problem related to the construction of artificial structures.

Alien reef-building polychaete drives long-term changes in invertebrate biomass and diversity in a small, urban estuary

Two of the greatest threats to native biodiversity are the construction of artificial structures in natural environments and the introduction of invasive species. As the development and urbanisation of estuaries continues at an increasing rate worldwide, these environments are being simultaneously affected by these threats. This study quantifies the spread of an invasive reef-building polychaete, Ficopomatus enigmaticus, in a small, highly manipulated urban estuary in South Africa and investigates its role as an ecosystem engineer. Anthropogenic changes to the Zandvlei Estuary, including construction of a rubble weir and canalisation near the estuary mouth, construction of an extensive marina development and hardening of the banks with concrete, have facilitated the expansion of F. enigmaticus. The standing stock of F. enigmaticus increased from 13.69 t, as measured in 1986, to 50.03 t in 2012, due both to increase in the total area colonised and standing stock per m2. Since F. enigmaticus reefs support a greater biomass of infauna than adjacent sandy areas, total invertebrate biomass in the estuary is estimated to have increased from less than 0.30 t in 1942, to over 56.80 t in 2012, due mainly to hardening of banks in parts of the main estuary with concrete and construction of a marina system. A positive correlation between reef mass and infaunal biomass, density and diversity was also found.

Time series analysis of shoreline changes in Gonghyunjin and Songjiho Beaches, South Korea using aerial photographs and remotely sensed imagery

Kim, I.H., Lee, H.S. and Song, D.S., 2013. Time series analysis of shoreline changes in Gonghyunjin and Songjiho Beaches, South Korea using aerial photographs and remotely sensed imageryGiven the speed and pervasiveness of anthropogenic landcover changes, especially in coastal areas, monitoring shoreline alterations and their impacts is critical for intelligent coastal development and beach use management. In this study, we describe a monitoring and analysis framework that uses aerial photography, remotely sensed imagery, and field surveys to detect changes in beach width and area along Gonghyunjin and Songjiho Beaches in South Korea. We used IKONOS imagery acquired in 2004; aerial photographs captured in 1991, 2005, 2009 and 2010; and field surveys conducted in 2010 and 2011. Based on comparisons of these data sources, we detected widespread erosion on both beaches starting in 2004, resulting in 12% reduction in the plane area of these beaches between 2004 and 2010. Most dramatically, we noted that beach width eroded by 28.5 m at the point 700 m south of Gonghyunjin Harbor, and similar declines occurred at several other locations. Erosion occurred at these locations because extended breakwaters in the Gonghyunjin Harbor either blocked or interrupted drift sand transport processes, causing sand to be carried away from some locations without accretion to replenish it. In addition, according to field surveys, we determined that erosion and accretion processes continued to vary seasonally in 2010 and 2011, resulting in smaller overall changes than those in the study years prior to 2010. However, we suggest that severe erosion may occur in the future at some locations if sand continues to be transported north onto Songjiho Beach without replenishment. Thus, we demonstrated that the construction of artificial structures around the harbor caused changes along the shoreline. Our monitoring framework has important applications for future observation of anthropogenically driven changes to this coastal area and serves as an applicable tool in other coastal regions worldwide.

Remote sensed data for automatic detection of land-use changes due to human activity in support to landslide studies

Slope instability studies appear to recognize a number of potential superficial slide-producing agents, which may be directly detected and monitored with Earth Observation (EO) data. The main objective of this work is to use conventional EO data and automatic techniques for providing land-use change maps useful in landslide prevention. The idea is to use the detection of changes in areas already involved in landslide events as a precursory sign of variations in the equilibrium status of the slope, independently from other natural triggering events, such as rain and seismic events. Attention is focused on man-induced surface changes, such as deforestation, urban expansion and construction of artificial structures.

タイ中央平原における近年の水害の変化について

The author has investigated micro-geomorphology for flooding area of the Chao Phraya River, the central plain of Thailand. The hydrological condition of the Chao Phraya River which takes the major part of this plain has been considerly changed for the last five decades through construction of artificial structures, such as embankments, multiple-purpose dams, storing reservoirs, barrages, irrigation ditches and drainage canals. This report describes a recent transformation of flooding in the plain.Changes of flood damage pattern are as follows : (1) The gradient of lower plain has been decreased according to extension of submarine delta and land subsidence. Therefore the water level of the Chao Phraya River at Bangkok has become higher than before. In densely populated areas, flood risk has been increased recently.(2) The shortened flood lag time due to increasing impermeable areas in this basin leads to a concentration of flood flow, and transmission of peak flood discharge has accelerated and aggravated flood disaster.(3) Inundation damages are also caused by the local rainfall in the plain. Artificial facilities, such as roads, dikes and structures for agricultural utilization of water etc., obstruct water to drain off the lower plain. These the river conditions are the reasons for increase of flood-prone areas.(4) Landside water flooding has occured at new urban sprawl areas as a result of rapid concentration of population from rural regions in the Bangkok Metropolitan Area.