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The primary purpose of this study is to identify whether there is a price premium and consumers’ preferences for higher housing density, and whether there is a relationship between housing densities and sales prices. The second purpose was to identify if there is a non-linear relationship between housing density and prices even though housing density is directly associated with housing prices.

This paper applies hedonic modeling techniques to measure the value of development density of apartments in the metropolitan area of Seoul, South Korea. The regression of the sale price is a function of different types of variables such as density, market, location and other control variables.

For the first question, this paper concludes that the higher densities cause housing prices to decrease in Seoul. The summary of the results presents that housing density, floor area ratio (FAR), building coverage ratio and floor level are all important components affecting housing prices. Generally, consumers tend to buy housing with central heating systems, more parking spaces, smaller portion of rental housing within an apartment and buildings that have more of a mixed-use function. Consumers are also found to pay higher premiums for housing in areas with high population growth and less housing supply. It is conclusive that people are inclined to live in populated areas but do not want more density. For the second question, the results show that generally FAR has quadratic effects, but most housing density variables tend to have a non-linear relationship depending on the different quantile groups.

There is a knowledge gap in the area of estimating development density of apartments. Generally, studies investigating property value impacts of multifamily housing focus on external effects of the multifamily housing on home values to examine whether high density development could result in a decrease in nearby property values. These studies found that there are some positive effects. A study found that high-density housing increases property values of existing single-family homes (Joint Center for Housing Studies, 2011). More specifically, developments that are of a high design quality and superior landscaping increase values of single-family homes as well. Also, those residents who live in these high-density apartments can be good potential buyers for the existing single-family homes. The greater the number of buyers, the greater the housing market becomes. Similarly, according to a report by the Joint Center for Housing Studies (2011) at Harvard University, the presence of multifamily residents correlates with higher home values in “working communities”. Indeed, density can be an important factor determining value of apartments because of its unique characteristics. However, no empirical evidence has been provided in the literature with regard to the value of the development density. This study contributes toward improving this knowledge gap.

This study aims to analyze the development direction of train speed, density and weight in China.

The development of China's railway in the past 40 years can be divided into 3 stages. At the stage of potential tapping and capacity expansion, it is important to improve the train weight and density by upgrading the existing lines, and improving transportation capacity rapidly. At the stage of railway speed increase, the first priority is to increase train speed, reduce the travel time of passenger train, and synchronously take into account the increase of train density and weight. At the stage of developing high-speed railway, train speed, density and weight are co-developing on demand.

The train speed of high-speed railway will be 400 km h⁻¹, the interval time of train tracking will be 3 min, and the traffic density will be more than 190 pairs per day. The running speed of high-speed freight EMU will reach 200 km h⁻¹ and above. The maximum speed of passenger train on mixed passenger and freight railway can reach 200 km h⁻¹. The minimum interval time of train tracking can be compressed to 5 min. The freight train weight of 850 m series arrival-departure track railway can be increased to 4,500–5,000 t and that of 1,050 m series to 5,500–6,400 t. EMU trains should gradually replace ordinary passenger trains to improve the quality of railway passenger service. Small formation trains will operate more in intercity railway, suburban railway and short-distance passenger transportation.

The research can provide new connotations and requirements of railway train speed, density and weight in the new railway stage.

This paper aims to provide a detailed study on influence of the laser energy density on mechanical, surface and dimensional properties of polyamide 12 (PA12) parts produced by selective laser sintering (SLS), providing the microstructural and crystallization evolution of the samples produced at different energy densities.

Making use of a space filling design of experiments, a wide range of laser sintering parameters is covered. Surface morphology is assessed by means of profile measurements and scanning electron microscopy (SEM) images. Mechanical testing, SEM, X-ray diffraction (XRD), differential scanning calorimeter (DSC) and infrared spectroscopy (FTIR) were used to assess the influence of energy density on structural and mechanical properties.

Results show a high dependency of the properties on the laser energy density and also a compromise existing between laser exposure parameters and desired properties of laser sintered parts. Surface roughness could be associated to overlap degree when using higher scan line spacing values and lower laser speeds improved surface roughness when high scan line spacing is used. Higher mechanical properties were found at higher energy density levels, but excessively high energy density decreased mechanical properties. A transition from brittle to ductile fracture with increasing energy density could be clearly observed by mechanical analysis and SEM. XRD and DSC measurements show a decrease on the crystal fraction with increasing energy densities, which corroborated the plastic behavior observed, and FTIR measurements revealed polymer degradation through chain scission might occur at too high energy densities.

Valuable guidelines are given regarding energy density optimization for SLS of PA12 considering not only quality criteria but also microstructure characteristics. Surface properties are studied based on the concept of degree of overlap between laser scanning lines. For the first time, crystallization behavior of SLS PA12 parts produced at different energy levels was studied by means of XRD measurements. Polymer degradation of SLS PA12 parts was evaluated with FTIR, which is a non-destructive and easy test to be conducted.

The purpose of this paper is to improve the performance and quality of Ti-6Al-4V fabricated by laser powder bed fusion.

Single-track experiments were conducted during the fabrication process to obtain the single tracks with excellent wettability to narrow the process parameter window. The effects of process parameters on the build surface, cross-section, relative density, defects, surface roughness, microstructure and mechanical properties of the parts were analyzed through multilayer fabrication experiments and surface optimization experiments.

The point distance has the greatest influence on the build surface of the fabricated parts, and the unmelted defects can be eliminated when the point distance is 35 µm. The relative density of the fabricated parts decreased with the increase of the point distance, and the hatch spacing has different characteristics with respect to the relative density of the fabricated parts under different laser powers. It was observed that the most of experimental groups with higher relative densities than 99%, and the highest density could reach 99.99%. The surface roughness can be reduced to less than 10 µm through remelting optimization.

The research results can provide theoretical support for scientific researchers and data support for engineers.

The introduction of higher density housing development within suburban areas has been favoured by state governments in Australia as a means of improving the efficiency of land use, reducing the costs associated with the delivery of government services and promoting home ownership. However it has been hypothesised that such development may have a negative impact on neighbourhood social structure, for example reducing diversity as measured by economic status and family makeup or in local housing market performance as measured by price. This paper aims to test this hypothesis.

The methodology employs a quantitative approach with principal components analysis used to capture the main social structure of the Adelaide Statistical Division. Social constructs, the product of principal components analysis, are used to measure outcomes of higher density development as measured by community or household change.

The results in this paper show that densification has had significant impact on certain neighbourhoods in the Adelaide Statistical Division notably in relation to their built form but not necessarily in neighbourhood structure or housing market performance.

The findings are significant in highlighting that increasing medium densities and improving tenure mix may not necessarily improve the opportunities for socio‐economic mix or for cultural diversity with implications for policy makers seeking to follow strategies based on the promotion of mixed communities.

This paper seeks to add new research on the outcomes of higher density development in Australia in three ways. First, social constructs, the product of principal components analysis, are used to measure outcomes of higher density development as measured by community or household change. Second, the paper investigates the development at the local level where impacts are likely to be most important. Third, the analysis identifies a before and after scenario for those suburbs where higher density development has been most significant.

Flex‐rigid circuits have been used for many years, primarily by the military, as a method to reduce the size and increase the reliability of electronic systems. However, in today's emerging designs where high speed ASICs are often the dominant components, flex‐rigid circuit assemblies are now an attractive solution for providing high density transmission line interconnects from board to board. Much of today's circuitry is being committed to ASIC designs to increase both circuit density and speed. Following this path, designers are faced with the task of interconnecting high lead count SMT packages often with as many as 300 to 500 leads per device, each dissipating several watts. At these power densities conductive cooling through the circuit board is often a necessity, dictating the use of either metal cores or heat exchangers. To make efficient use of the core and minimise weight, designs generally require SMT packages to be mounted on both sides of the core with electrical communication from side to side. However, as more exotic core materials (carbon fibre matrix, beryllium, etc.) and liquid cooled heat exchangers are used, electrical communication through the core has become difficult, if not impossible, in some cases. Instead, high density flex‐rigid assemblies are used to partition the circuit, allowing the board to ‘fold’ over the core. This results in hundreds of signal lines that must cross the flex, obeying the electrical design rules dictated by the rigid sections to maintain impedance values and crosstalk margins. This paper focuses on recent work at AIT, producing high density flex‐rigid circuits using embedded discrete wiring technology to meet the above requirements. Using 0.0025 in. diameter polyimide insulated wire, as many as 100 lines per linear inch can pass over the flex region on a single layer. This generally results in a single flex layer where all wires can be referenced to a continuous ground plane from board to board. Controlled impedance is easily maintained due to the uniform wire geometry, and high frequency attenuation is significantly lower than on equivalent etch circuit designs due to the smooth surface finish on the wire. In addition, the high interconnection density offered by this technique reduces the overall thickness of the rigid sections, thereby minimising the thermal resistance to the core.

In binder jetting, the interaction between the liquid binder droplets and the powder particles defines the shape of the printed primitives. The purpose of this study is to explore the interaction of the relative size of powder particles and binder droplets and the subsequent effects on macro-scale part properties.

The effects of different particle size distribution (5–25 µm and 15–45 µm) of stainless steel 316 L powders and droplet sizes (10 and 30 pL) on part density, shrinkage, mechanical strength, pore morphology and distribution are investigated. Experimental samples were fabricated in two different layer thicknesses (50 and 100 µm).

While 15–45 µm samples demonstrated higher green density (53.10 ± 0.25%) than 5–25 µm samples (50.31 ± 1.06%), higher sintered densities were achieved in 5–25 µm samples (70.60 ± 6.18%) compared to 15–45 µm samples (65.23 ± 3.24%). Samples of 5–25 µm also demonstrated superior ultimate tensile strength (94.66 ± 25.92 MPa) compared to 15–45 µm samples (39.34 ± 7.33 MPa). Droplet size effects were found to be negligible on both green and sintered densities; however, specimens printed with 10-pL droplets had higher ultimate tensile strength (79.70 ± 42.31 MPa) compared to those made from 30-pL droplets (54.29 ± 23.35 MPa).

To the best of the authors’ knowledge, this paper details the first report of the combined effects of different particle size distribution with different binder droplet sizes on the part macro-scale properties. The results can inform appropriate process parameters to achieve desired final part properties.

The urban population in Indian cities is increasing at an alarming speed. Accommodating such a huge population while sustaining the environment is a challenge in urban areas. Compact urban forms with high-density planning is claimed to be a sustainable solution in such situations. Thus, this approach needs to be tested for Indian urban areas.

This paper formulates a neighbourhood sustainability assessment (NSA) framework for monitoring, assessing and managing the population density of urban neighbourhoods. The paper identifies context-specific built density indicators at the neighbourhood scale. It assesses the indicators in neighbourhoods with varying population density by physical and perceived measures. This helps in verifying the feasibility of density by physical density assessment and verifies the acceptability of density by perceived density assessment.

When tested in the Indian context, the framework shows that although high-density neighbourhoods are sustainable, certain indicators may endorse differing densities. The result displays that high-density planning is sustainable compared to low- and medium-density neighbourhoods in the selected cities.

The study demonstrates the application of formulated assessment system in three central Indian cities with useful results. Similar studies can be conducted to identify the gaps for improving sustainability and achieve a livable density pattern.

Although sustainable development goals are part of new planning policies, there exist very few assessment systems to determine the sustainability of neighbourhoods, especially for density. The methodology will assist in developing sustainability assessment frameworks and encourage the practice of sustainability assessment in developing countries like India.

In today’s ever-increasing context of volatile, uncertain, complex and ambiguous market conditions, the shifts of countries’ protectionist policies toward inward Foreign Direct Investment (FDI), and an increased gap between headquarters’ (HQ) and subsidiaries’ perspectives on what makes business sense, it has become apparent that challenges toward foreign expansion are becoming more severe and require a multidimensional dynamic approach. The authors draw from orchestration theory, dynamic capabilities literature and previous literature on dimensions of internationalization [specifically, density, geographic distance and degree of diversity of the multinational corporation (MNC) subsidiary network] to argue that firms must enhance their orchestration capability. In doing so, this study aims to highlight the nuances of orchestrating a three-dimensional (3D) conceptualization of MNCs’ international configurations.

The authors analyzed the patterns of configurations that are adopted by MNCs. This sample was made up of the international configuration of 78 Fortune 500 MNCs consisting of 3,318 foreign subsidiaries. Furthermore, the authors examined the impact of different configurations of the 3Ds on firm performance using ordinary least squares regression analysis.

While the research did indicate that the sample MNCs adopted the sample configurations of the three internationalization dimensions more frequently than others, the authors found that orchestrating MNCs with an international configuration characterized by high density, low geographic distance and low internetwork scope diversity had a positive impact on firm performance.

While international expansion is often motivated by financial performance or market/resource gains, it is also impacted by the firm’s dynamic capability profile. Thus, as MNCs seek to continue to expand globally, they must assess and, if needed, develop their management team’s orchestration capability, which includes effectively determining how the addition or removal of a subsidiary will impact the density, geographic distance and diversity dynamics of the MNC’s international configuration. Finally, the management team needs to be able to devise plans to respond to the potential challenges associated with each of these dimensions.

The contribution of this study includes bringing a dynamic capabilities lens to the extant international business literature examining the multinationality and performance relationship by highlighting the importance of an MNC’s process orchestrating capability that is needed for firms to effectively manage increasingly complex subsidiary networks. It also conceptually explains and empirically supports that some configurations are likely to yield higher returns than others, which can act as a guide for firms as they are seeking to expand in more geographically distant as well as diverse sectors. Furthermore, this study highlights the need for a multidimensional simultaneous approach to the examination of internationalization to performance relationship. Finally, it highlights the tradeoffs that MNCs must address across the orchestration of the three internationalization dimensions using a dynamic capabilities theoretical lens that acknowledges the differences in perspective that exist between HQs and subsidiaries.

The microseismic monitoring technique has great advantages on identifying the location, extent and the mechanism of damage process occurring in rock mass. This study aims to analyze distribution characteristics and the evolution law of excavation damage zone of surrounding rock based on microseismic monitoring data.

In situ test using microseismic monitoring technique is carried out in the large-span transition tunnel of Badaling Great Wall Station of Beijing-Zhangjiakou high-speed railway. An intelligent microseismic monitoring system is built with symmetry monitoring point layout both on the mountain surface and inside the tunnel to achieve three-dimensional and all-round monitoring results.

Microseismic events can be divided into high density area, medium density area and low density area according to the density distribution of microseismic events. The positions where the cumulative distribution frequencies of microseismic events are 60 and 80% are identified as the boundaries between high and medium density areas and between medium and low density areas, respectively. The high density area of microseismic events is regarded as the high excavation damage zone of surrounding rock, which is affected by the grade of surrounding rock and the span of tunnel. The prediction formulas for the depth of high excavation damage zone of surrounding rock at different tunnel positions are given considering these two parameters. The scale of the average moment magnitude parameters of microseismic events is adopted to describe the damage degree of surrounding rock. The strong positive correlation and multistage characteristics between the depth of excavation damage zone and deformation of surrounding rock are revealed. Based on the depth of high excavation damage zone of surrounding rock, the prestressed anchor cable (rod) is designed, and the safety of anchor cable (rod) design parameters is verified by the deformation results of surrounding rock.

The research provides a new method to predict the surrounding rock damage zone of large-span tunnel and also provides a reference basis for design parameters of prestressed anchor cable (rod).