Infill Area Research Articles

Research on a Support-Free Five-Degree-of-Freedom Additive Manufacturing Method.

When using traditional 3D printing equipment to manufacture overhang models, it is often necessary to generate support structures to assist in the printing of parts. The post-processing operation of removing the support structures after printing is time-consuming and wastes material. In order to solve the above problems, a support-free five-degree-of-freedom additive manufacturing (SFAM) method is proposed. Through the homogeneous coordinate transformation matrix, the forward and inverse kinematics equations of the five-degree-of-freedom additive manufacturing device (FAMD) are established, and the joint variables of each axis are solved to realize the five-axis linkage of the additive manufacturing (AM) device. In this research work, initially, the layered curve is obtained through the structural lines of the overhang model, and a continuous path planning of the infill area is performed on it, and further, the part printing experiments are conducted on the FAMD. Compared with the traditional three-axis additive manufacturing (TTAM) method, the SFAM method shortens the printing time by 23.58% and saves printing materials by 33.06%. The experimental results show that the SFAM method realizes the support-free printing of overhang models, which not only improves the accuracy of the parts but also the manufacturing efficiency of the parts.

Linkages between urban growth and land surface temperature variations in the Seoul metropolitan area: A spatial first-order difference approach

This study investigates the effects of urban development and expansion on Land Surface Temperature (LST) changes from 2000 to 2018, using the Seoul Metropolitan area (SMA) as a case study area. Along with descriptive analysis, this study uses a spatial first-order difference model to statistically analyze the longitudinal relationship between land use features and LST, including impervious surface (IS), enhanced vegetation index (EVI), anthropogenic factors, and urban spatial and topographical factors as well as urban development types as influential factors on LST variations. Our findings support prior research indicating the cooling effects of vegetation and warming effects of imperviousness. We also found a positive association between detached housing units, manufacturing activities and LST changes and a negative relationship between apartment units, urban parks, service activities and LST changes. More importantly, substantial LST reduction was found in the large-scale high-rise apartment complexes redeveloped from the low-rise, detached housing sites in inner-city infill areas, contrasting with significant LST rise in the suburban new town development. We suggest redevelopment of inner-city low-rise compact areas into high-rise but greener blocks as a LST mitigation strategy, equipped with cooling strategies such as green infrastructure and climate-sensitive design considering local microclimate and natural ventilation.

Ensuring Ecosystem Service Provision of Urban Water Nature-Based Solutions in Infill Areas: Comparing Green Factor for Districts and SWMM Modeling in Scenario Assessment

This study aims to explore the measurement of potential synergies between water management objectives and other ecosystem services generated by Nature-Based Solutions (NBS) in the context of urban planning. The research also investigates the comparative benefits of two analytical methods, Storm Water Management Model (SWMM) and green area factor for districts (GAFD). The study employs Malmi district in Helsinki, Finland, as a case study, examining five distinct NBS scenarios with varying degrees of integration. The results affirm that NBS can indeed enhance ecosystem services provision and stormwater management. The comparative analysis of the two methods, reveals that scenarios with high green factors exhibit effective flood risk reduction, while those with low green factors struggle to manage water, emphasizing the importance of balancing green and built elements in urban planning for optimal flood risk reduction. Furthermore, the study underscores the advantages of the two methods: GAFD offers simplicity and lower expertise requirements, generating valuable insights into ecosystem services, while SWMM provides precise stormwater management data. The findings emphasize the significance of diverse NBS combinations that harness the multifunctional aspects of green infrastructure, highlighting the need for integrated urban planning. The utilization of GAFD analysis provides a comprehensive districtwide perspective in a flexible manner, thereby improving the comprehension of the interconnected nature of urban green spaces.HighlightsNature-based solutions (NBS) support urban stormwater management in infill areas.Green Area Factor for Districts (GAFD) is a practical tool to compare NBS options.GAFD and SWMM modeling results on stormwaters are comparable for common rain events.NBS size, quality and diversity reduce peak flows and enhance ecosystem services.Assessment of scenarios with the GAFD tool helps to identify multiple benefits of NBS.

Influence of Pulsed Exposure Strategies on Overhang Structures in Powder Bed Fusion of Ti6Al4V Using Laser Beam

Manufacturing structures with low overhang angles without support structures is a major challenge in powder bed fusion of metals using laser beam (PBF-LB/M). In the present work, various test specimens and parameter sets with continuous wave (cw) and pulsed exposure are used to investigate whether a reduction of downskin roughness and overhang angle can be achieved in PBF-LB/M of Ti6Al4V. Starting from cw exposure, the limits of overhang angle and surface roughness at the downskin surface are investigated as a reference. Subsequently, the influence of laser power, scanning speed, and hatch distance with fixed pulse duration (τpulse = 25 µs) and repetition rate (υrep = 20 kHz) on surface roughness Ra is investigated. Pulsed exposure strategies enable the manufacturing of flatter overhang angles (≤20° instead of ≥25°). Furthermore, a correlation between the introduced volume energy density and the downskin roughness can be observed for pulsed exposure. As the reduction in volume energy density causes an increase in porosity, the combination of pulsed downskin exposure and commercial cw infill exposure is investigated. The larger the gap in volume energy density between the infill area and downskin area, the more challenging it is combining the two parameter sets. By combining cw infill and pulsed downskin exposure, flatter overhang structures cannot be manufactured, and a reduction in roughness can be achieved.

Artvin Rize Havalimanı’nın Ulaşıma ve Çevreye Etkileri

In transportation, the demand for air transportation, that serves fast and comfortable passenger transportation, increases day by day. This situation triggers airport investments. Although airport investments make economic and social contributions, they cause many negative environmental impacts. When there is not sufficient area for airports, offshore infill areas increase the negative environmental impacts. The reduction of living and plant species in the sea, air and water pollution, cause adverse impacts such as climate change and soil pollution. If precautions are not taken, irreversible damage will occur. For this reason, the necessity of the investment should be well analyzed, the damage to the environment should be minimized, and the measures should be planned. In the study, the environmental effects that may occur during the construction process of Artvin-Rize Airport and after launch were examined. The positive and negative aspects were put and recommendations were made.

Prediction of interwell connectivity and interference degree between production wells in a tight gas reservoir

Sulige gas field has poor reservoir physical properties and strong heterogeneity. The existing development well pattern is difficult to realize the overall effective production of reserves, especially in block SuX. Therefore, this paper takes SuX block in the east of Sulige as an example to describe an effective method suitable for the development of well pattern in this area. Combined with logging and production data, the connectivity of gas wells in X infill area in the east of Sulige is determined from the aspects of pressure, sand body, logging, performance and well test. By using the method of dynamic and static analysis, the connectivity between wells of main gas reservoir is judged. Through the analysis of flow unit, the discharge area and the stable value of well-controlled reserves are determined. The degree of interference determined by curve fitting and the distribution characteristics of sand bodies are comprehensively analyzed. A new oil well interference degree model defined by mathematical expression of production is established. The interference degree is quantified by gas production through numerical simulation. Based on the comprehensive analysis of the connectivity, interference degree and other factors in the area, it is determined that 500 * 600 well pattern is a reasonable well pattern in SuX block, and the interference degree is about 20%. Based on the analysis of the connectivity between wells and the interference degree between production wells in SuX block, the distribution and connectivity of sand bodies in tight sandstone gas field under complex geological conditions are determined. It provides a reasonable basis for the network encryption development of tight sandstone gas in this block. It provides a powerful technical support for the efficient development of different tight gas reservoirs in Sulige area.

Region-based layered infill area generation of STL models for additive manufacturing

PurposeIn the implementation of large-size additive manufacturing (AM), the large printing area can be established by using the tiled and fixed multiple printing heads or the single dynamic printing head moving in the x–y plane, which requires a layer decomposition after the mesh slicing to generate segmented infill areas. The data processing flow of these schemes is redundant and inefficient to some extent, especially for the processing of complex stereolithograph (STL) models. It is of great importance in improving the overall efficiency of large-size AM technics software by simplifying the redundant steps. This paper aims to address these issues.Design/methodology/approachIn this paper, a method of directly generating segmented layered infill areas is proposed for AM. Initially, a vertices–mesh hybrid representation of STL models is constructed based on a divide-and-conquer strategy. Then, a trimming–mapping procedure is performed on sliced contours acquired from partial surfaces. Finally, to link trimmed open contours and inside-signal square corners as segmented infill areas, a region-based open contour closing algorithm is carried out in virtue of the developed data structures.FindingsIn virtue of the proposed approach, the segmented layered infill areas can be directly generated from STL models. Experimental results indicate that the approach brings us the good property of efficiency, especially for complex STL models.Practical implicationsThe proposed approach can generate segmented layered infill areas efficiently in some cases.Originality/valueThe region-based layered infill area generation approach discussed here will be a supplement to current data process technologies in large-size AM, which is very suitable for parallel processing and enables us to improve the efficiency of large-size AM technics software.

Efficient generation strategy for hierarchical porous scaffolds with freeform external geometries

The external geometry design and manipulation of internal porosity distribution according to the actual application demands are the main challenges of scaffold generation; moreover, computational efficiency is a key factor that should be considered. This paper proposes efficient generation strategies for constructing internal porous architectures by using triply periodic minimal surfaces (TPMSs) and external freeform shapes through T-spline surfaces. After discretizing the geometries as slicing contours, TPMSs can be efficiently extracted using the intersection-interpolation method in 2D space, and then be offset as infill areas of sheet solids. Based on the proposed fractal sheet TPMSs, hierarchical scaffolds are further generated using the refined constrained Delaunay triangulation method to construct multiscale pores. The porosity features can be conveniently controlled in 2D space according to the actual computed tomography images. Eventually, the resulting infill areas can be directly fabricated as scaffolds by additive manufacturing technology. Several experimental instances validate the effectiveness and efficiency of the proposed strategies.

Layered infill area generation from triply periodic minimal surfaces for additive manufacturing

Compared with widely applied tessellation mesh or parametric spline surfaces, implicit surfaces are more suitable for representing models with complicated topology and geometry. Triply periodic minimal surface (TPMS) is a kind of charming implicit surface talented at designing porous structures. Layered infill area generation is the crucial task of process planning for additive manufacturing (AM). Generally, the constructed TPMS are open surfaces with zero thickness, which cannot be directly fabricated. In this work, a complete method is proposed to generate layered infill areas from TPMS for AM. Initially, based on the Marching Squares (MS) algorithm, the TPMS can be efficiently sliced into numerous unstructured line segments. Afterwards, an efficient sorting algorithm with a linear time complexity is developed by special data structures to generate ordered slicing contours. Eventually, in virtue of the demonstrated bidirectional-offset-union strategy, close polygons can be generated as layered infill areas for path planning procedure to manufacture TPMS structures with uniform wall thickness. Experimental results verify the effectiveness and merits of the proposed approach, which can also be expanded to fabricate other complicated implicit surfaces via AM technology.

The Nonlinear Effect of Infill Walls Stiffness to Prevent Soft Story Collapse of RC Structures

Experimental or theoretical tests show that dramatically changes of infill area causes soft mechanism. Soft story mechanism is the most frequent failure mode of reinforced concrete (R.C.) structures. This phenomenon is caused by the fact that the overall shear force applied to the building by an earthquake is higher at the base floor. If the lower is not originally weakened, it is however there that infill are the most stressed, so that they fail first and create the weak and finally leads collapse of structures. This kind of collapse was observed many times in Turkey caused by earthquake. The aim of this paper is to show the contribution of infill walls to the building response during earthquake. Different type of configuration of infill walls are modeled and analyzed by the Finite Element Method. These models also have soft risk. The nonlinear force-displacement behavior is used for structural analysis. El Centro N-S component is used for time-history analysis.

Shear wave velocity structure of the İzmit Bay area (Turkey) estimated from active-passive array surface wave and single-station microtremor methods

SUMMARY To provide quantitative information on the shear wave velocity structure of the Izmit Bay area, we conduct active–passive array surface wave and single-station microtremor measurements at 60 sites. We process these array measurements to produce combined Rayleigh wave dispersion curves that span a broad-frequency range (0.5–20 Hz). We also make use of horizontal-to-vertical spectral ratio (HVSR) curves obtained from the single-station microtremor measurements to benefit from their close relation to the ellipticity of Rayleigh waves. Using the dispersion curve sensitivity to the absolute velocities and the shape of the HVSR curve sensitivity to the velocity contrasts of the velocity-depth model, we have applied a combined inversion technique to derive better constrained shear velocity models at each site. The derived shear velocity models are used to provide a Vs30 site classification map and information on the sediment-bedrock structure for the Izmit Bay area. The Vs30 map shows that the entire shoreline regions including artificial infill areas of the Izmit Bay have Vs30 values less than 200 m s−1, locally as low as 80 m s−1. The older sediment areas of the Izmit basin have Vs30 values ranging between 250 and 350 m s−1. The highest Vs30 values are associated with rock sites reaching about 950–1300 m s−1. We also present a high correlation between the Vs30 values and the phase velocity of Rayleigh wave corresponding to the 40 m wavelength (C40). The important implication of this correlation is that Vs30 may be estimated from C40 without inverting the dispersion curve. The inferred sediment-bedrock interface along a cross-section shows an antisymmetric V shaped basin with a sedimentary cover thickness reaching about 1200 m at the deepest part of the Izmit basin. This deepest part coincides in the map view where the North Anatolian fault zone crosses the basin in the east–west direction. The sedimentary cover thickness is found to be 750 m in the Golcuk–Derince basin.

Assessing Extrajurisdictional and Areawide Impacts of Clustered Brownfield Developments

Brownfields are vacant, underutilized, or abandoned industrial and commercial sites where real or perceived environmental contamination is an obstacle to development. Federal initiatives in the 1990s reduced legal liabilities associated with brownfields and provided financial incentives for development initiatives. As brownfields are often located in infill areas, they have advantages over greenfields developments in that much of the supporting infrastructure already exists and they are centrally located. However, the existing infrastructure may be deteriorated and obsolete, and brownfield developments in infill areas may require local as well as areawide transportation improvements. This paper uses a modified impact analysis approach, synthesized from regional transportation modeling and site impact analysis tools, to assess the extrajurisdictional and areawide impacts of clustered brownfield developments. The writers apply this approach to clustered brownfield developments in the City of Pittsburgh. The study results show that the synergistic effects and areawide impacts of clustered brownfield developments may not be adequately captured by traditional site impact studies. This paper is potentially useful for municipal agencies involved in assessing and planning for the transportation improvement needs of clustered brownfield developments.

Microseismic monitoring of the infill trial at Castlefields Mine, Dudley

Abstract During the infill trial at Castlefields Mine, a network of geophones and seismometers was used to monitor any seismic activity associated with roof or pillar failure. Roof-falls in the infill area were not excessive (38 were detected in three months of overnight recordings), and there was no evidence of any very large collapses in this part of the mine during the infill trials. Records of activity in the non-infill area of the accessible mineworkings, which was used for test pumping of infill materials, suggested a relatively high rate of deterioration in this area. A crownhole, which appeared above the flooded workings some 150 m north of the monitored area prior to the main infill, did not produce any dramatic seismic events on the back-up recording system. However, the detection of some possible precursor events indicates that the seismic monitoring technique might provide warning, even at this late stage in the crownhole’s development, with a more localized network.

Roof-fall observations at Castlefields Mine, Dudley

Abstract The progressive collapse of old limestone mines has led to problems of general subsidence and crownhole formation in parts of the West Midlands. Infilling the voids inhibits the collapse of old workings, and a trial was undertaken at Castlefields Mine, Dudley, to assess the suitability of locally available colliery spoil, mixed with water to form a rock paste, as an infill material. As part of the site investigation programme prior to the infilling trial, information was obtained on the rate and size of roof collapses in the mine. Existing roof-fall debris piles were covered with netting and inspected at intervals over the 12-month period preceding the infill. Information on roof-falls was pertinent to the design and construction of the underground barrier which was to seal off the proposed infill area from the rest of the mine. The information was also required for the design of a network of transducers intended to monitor the microseismicity associated with rock failure and roof-falls in the mine. Rates of collapse were higher than expected, with an estimated total weight of approximately twenty-six tonnes. The absence of freshly exposed surfaces indicated that little fracturing was taking place. This led to a shift in emphasis in the microseismic monitoring programme, from the detection of high frequency fracture propagation to that of the impact of roof-falls on the mine floor. The observed distribution of roof-falls, which conformed with the jointing pattern in the mine, resulted in a change of plan for the position and make-up of the infill barrier. Identification of particularly unstable areas was also of considerable value with regard to the safety of personnel within the mine during the engineering operations associated with the infill trial.

An approximate method of analysis for infilled frames with or without opening

To deal with infilled frames with or without opening in the infill, an approximate method of analysis based on the concept of equivalent frame is presented. Experimental results on the stiffnesses of two elastic models having various sizes of opening in the infill are compared with the analytical results. The comparison shows good agreement when the central opening is more than half of the full infill area.

Timber-masonry Composite Structures - ABearing Structure Model

Timber is the principal material used in old framework buildings. Present research suggests that the vertical loads are exclusively applied to the timber girders, but the timber frame can not bear all vertical loads if the posts are spaced wide apart. These structures have nevertheless remained stable for over 100 years. Our present knowledge is not sufficient to determine the ultimate load-bearing capacity of this type of construction which has gone out of use. The Institute has conducted practical tests and theoretical studies which make it possible to forecast buckling failures for wall systems as a function of vertical load. 1 Structure and material 1.1 Structure Stud walls are framework structures in which the spacing of some posts equals their length, giving square infill areas in a number of cases. There is normally no strutting, with the exception of the bays nearest to the outer wall, and the attic. The cross section of the pine timber posts suits the wall thickness which is !4 brick (12 cm thick). The horizontal girders are head rails arranged under the floor beams. (Fig. 1) The masonry is butt-jointed to the timber structure. Recesses in the posts and mortar-sealed joints between the posts and masonry are rare. Equilibrium moisture Transactions on the Built Environment vol 39 © 1999 WIT Press, www.witpress.com, ISSN 1743-3509 46 Structural Studies, Repairs and Maintenance of Historical Buildings Figure 1: building with the descripted form of framework was achieved in covered open buildings by allowing them to stand empty for one winter before putting in windows, followed by alternate heating and airing to drive out more moisture. 1.2 Material To simplify classification, timber quality can be described as grade 10 (DIN 4074) in present terms (pine wood). The carpenters of the time selected timbers by appearance, and members intended for high loads will often have been of an even better grade, but this will be neglected here. Due to a strong demand for bricks, the number of clay pits and brick yards rose rapidly, with new types of bricks being developed and patented all the time. Brick quality therefore differed largely even within a single building. In our studies, three different strength classes for bricks (Fig. 2) were found in four walls of two buildings erected almost at the same time (1874 and 1876). For another Transactions on the Built Environment vol 39 © 1999 WIT Press, www.witpress.com, ISSN 1743-3509 Structural Studies, Repairs and Maintenance of Historical Buildings 47 building with inner walls made of porous bricks, a statistically significant average compression strength was established. Mortar quality is very much a function of aging, and chemical analysis of mortar composition at the time of production allows no conclusion as to its present compression strength. Partial sampling so far would put most of the masonry structures only in mortar group I. Following Brocker's findings, the admissible compression stress is assumed to be c=0.6N/mnf (Brb'cker, [1]). 20.00