Spatial configurations,competition and welfare

Studies into the shapes of market areas abound and emphasize the hexagon as the optimal configuration. This paper demonstrates that a triangular or a square market area can be superior to a hexagonal one under certain behavioural conditions. Spatial configurations are evaluated on the basis of (1) the number of firms required to fill a given market area and (2) the level of welfare per unit area that these firms generate under alternative competitive conditions.     

Tuned-pendulum mass damper installed in crystal tower

A new damper to reduce the lateral vibration of buildings has been developed and installed in a 37-story office building: Crystal Tower, Osaka. The tower has a slender proportion of height—width ratio 6. The damper can decrease wind-induced motion by 50%. Crystal Tower is the first high-rise building with this damper in Japan, and the damper weight, 540 tons (1190 kips), is large compared with others in use elsewhere in the world. The damper is a pendulum-type tuned-mass damper and the ice thermal storage tanks for air conditioning are used as the moving mass of the damper. The TMD of Crystal Tower, therefore, needs no additional mass weight nor space for installing. This paper presents some intrinsic features of the damper and demonstrates how simple and practical the damper is. Special considerations are given both to the connecting joints between the tank and the building and also to the sloshing behavior of the liquid contents. Typhoon and earthquake records observed in Crystal Tower have proved that the damper works as well as expected.     

A batchSPP/G/1 queue with multiple vacations and exhaustive service discipline

This paper considers a batch-arrival single-server queueing system with multiple vacations and exhaustive service discipline. Customers arrive to the system in accordance with a batch switched Poisson process (batchSPP). Using the supplementary variable technique, we analyze the stationary queue length distribution and derive various formulas for queue lengths and waiting times. In particular, we analytically show the decomposition property for the waiting time distributions. Therefore, the waiting time formulas developed in this paper can also be applied to a batchSPP/G/1 queue without vacations.     

Analysis of a nonpreemptive priority queue with SPP arrivals of high class

This paper considers a nonpreemptive priority queueing system with two priority classes of customers, where high priority customers arrive to the system in accordance with a switched Poisson process (SPP) and low priority customers in accordance with a Poisson process. Using the supplementary variable technique, we derive the joint probability generating function of the stationary queue length distributions and the Laplace-Stieltjes transforms of the stationary waiting time distributions of high and low priority customers. We also present some numerical results in order to show the computational feasibility of the analytical results.     

Sustainability assessment of cities: SDGs and GHG emissions

ABSTRACT

The United Nations’ (UN) sustainable development goals (SDGs), the core of the 2030 Agenda for Sustainable Development and the UN Paris Agreement, were adopted in 2015. Involvement of not only national governments but also all other stakeholders including local governments is important to promote sustainable development and to achieve the goals. The question arises, therefore, of what methods should be used to best implement and assess sustainability issues at a local level. In this light, a new version of Comprehensive Assessment System for Built Environment Efficiency (CASBEE), CASBEE for Cities, is introduced for assessing the sustainability of cities and communities around the world based on SDG indicators and greenhouse gas (GHG) emissions. The tool allows users to understand the sustainability of cities and communities based on quality (Q) and environmental load (L) perspectives. The sustainability assessments show that cities in developed countries tend to have good grades for Q, but bad grades for L, while cities in developing countries tend to have the opposite trend. This will assist cities and communities in both developed and developing countries to understand urgent problems and to identify effective solutions for sustainable development.     

Effects of Grafting Maleic Anhydride onto Poly-ɛ-caprolactone on Facilitative Enzymatic Hydrolysis

Plastic waste is a global issue because it causes overflowing landfills and pollution, leading to environmental concerns. To address this crisis, materials that can be decomposed in the natural environment are introduced to replace conventional plastics. Poly-ɛ-caprolactone (PCL) is a commonly used plastic that can degrade in natural environments. However, owing to its hydrophobicity, its natural decomposition rate is low. In this study, PCL is modified with maleic anhydride (MA) (PCL-g-MA) to increase hydrophilicity and amorphous region for faster decomposition. To assess the hydrolysis in seawater, lipase hydrolysis is performed to compare the decomposition of PCL-g-MA and PCL. Consequently, in a Pseudomonas lipase-containing PBS solution, it takes 72 and 120 h for complete hydrolyze of PCL-g-MA and PCL, respectively. MA grafted onto PCL increases the amorphous region, where lipase can easily diffuse into PCL-g-MA. Morphological (FESEM and POM images), thermal (TGA and DSC), and structural (FTIR, XRD, and XPS) analyzes support the hydrolysis reaction. The mechanisms proposed in this study confirm that lipase hydrolysis starts in the amorphous regions and then transfers to the crystal regions. This hydrolysis progress is expected to facilitate the creation of eco-friendly low-cost PCL-g-MA composites with high-rate hydrolysis, such as bio-plastics and bio-fibers.