A Fluid-Diffusion-Hybrid Limiting Approximation for Priority Systems with Fast and Slow Customers

The paper “Fluid-Diffusion-Hybrid (FDH) Approximation” proposes a new heavy-traffic asymptotic regime for a two-class priority system in which the high-priority customers require substantially larger service times than the low-priority customers. In the FDH limit, the high-priority queue is a diffusion, whereas the low-priority queue operates as a (random) fluid limit, whose dynamics are driven by the former diffusion. A characterizing property of our limit process is that, unlike other asymptotic regimes, a non-negligible proportion of the customers from both classes must wait for service. This property allows us to study the costs and benefits of de-pooling, and prove that a two-pool system is often the asymptotically optimal design of the system.

Application of the Swimming Pool Backwash Water Recovery System with the Use of Filter Tubes

During the operation of swimming pools, large losses of water from the backwash of swimming pool filters are observed. This water is often discharged into sewers or used to sprinkle sports grounds. The aim of the research was to design and build an installation for purification and recovery of backwash water (BWW). It consists of flocculation, pre-filtration, and ultrafiltration based on filter tubes and ozone disinfection. Backwash water treatment installation contributes to purification and improvement of water quality. The effectiveness of the removal of microbial contamination with the use of the system was over 99%. The high efficiency of removing physicochemical impurities was also achieved. Water turbidity was reduced from 96.9 NTU to 0.13 NTU. After using the system, the oxidability of water decreased from 6.26 mg O2∙dm−3 to 0.4 mg O2∙dm−3. When using the system, a reduction of total organic carbon by 80% was also noticed. After the treatment process, water meets the strict criteria and can be returned to the pool system of water as fresh water with parameters of supply water—directly to the overflow tank. It has been shown that up to 96% of water can be recovered with the technology. The cost comparison showed annual savings of over EUR 9,000.

Exploring Multiple Aspects of Taxonomic and Functional Diversity in Microphytobenthic Communities: Effects of Environmental Gradients and Temporal Changes

Biodiversity has traditionally been quantified using taxonomic information but the importance of also considering its functional characteristics has recently gained an increasing attention among microorganisms. However, studies exploring multiple aspects of taxonomic and functional diversity and their temporal variations are scarce for diatoms, which is one of the most important microbial groups in aquatic ecosystems. Here, our aim was to examine the taxonomic and functional alpha and beta diversities of diatoms in a coastal rock pool system characterized by a naturally high environmental heterogeneity. We also investigated the temporal differences in the diversity patterns and drivers. The relationship between the species richness and functional dispersion was temporally coherent, such that species-poor communities tended to be functionally clustered. The trend between the species richness and taxonomic uniqueness of community composition was temporally inconsistent, changing from negative to non-significant over time. Conductivity or distance to the sea or both were key determinants of species richness, functional dispersion, and uniqueness of community composition. The increase of community dissimilarity with an increasing environmental distance was stronger for the taxonomic than the functional composition. Our results suggest that even minor decreases in the species richness may result in a lowered functional diversity and decreased ecosystem functioning. Species-poor ecosystems may, however, have unique species compositions and high contributions to regional biodiversity. Despite changing the species compositions along the environmental gradients, communities may remain to have a high functional similarity and robustness in the face of environmental changes. Our results highlight the advantage of considering multiple biodiversity metrics and incorporating a temporal component for a deeper understanding of the effects of environmental changes on microbial biodiversity.

Role of baffle shape on debris flow impact in step-pools channel: an SPH study

Drainage channels with step-pool system are widely used to control debris flow. The blocking of debris flow often gives rise to local damage at the steps and ba?es. Hence, the estimation of impact force of debris flow is crucial for designing step-pools channel. Existing empirical models for impact pressure prediction cannot consider the influence of baffle shape. In this work, a three-dimensional smoothed particle hydrodynamics (SPH) study on the impact behaviour of debris flows in step-pool systems is presented, where debris material is modelled using the regularizedBingham model. The SPH method is first checked using the results from two laboratory tests. Then it is used to investigate the influence of bafflee shape and flow density. Numerical results show that the impact pressure at the first ba?e highly depends on the ba?e shape; however, the largest impact pressure usually occurs at subsequent baffles due to the violent impact induced by jet flows. The peak impact pressure at the first ba?e initially grows with increasing flow density; however, it starts to drop as density is beyond a threshold. Based on the numerical results, an empirical relation considering the influence of ba?e shape is proposed for better prediction of debris impact pressure.

Warm Water Pool System Simulation: Design and Manufacture

Human development and national competitivenes is one of the flagship programs from The Indonesian Government. Bali as one of the best tourist destination in the world is required to have an international standard tourism infrastructure. A swimming pool in a tourism accomodation is a standard facility in a tourist infrastructure. There are several types of swimming pools i.e. public swimming pools and private pools. During its development and demand, private pools develop into swimming pools with additional facilities such as warm water, which is often called a jacuzzi. Another additional facility is added pressure to the water in completing massage, fragrance and foam. The swimming pool is one of facilitity designed to hold water to allow swimming or other recreational activities. Pools can be built in the ground or on the ground as a free construction or as a part of structure and also with a common feature or a free style design. In-ground pools are the most common pools made and constructed from materials such as concrete, natural stone, metal, plastic, or fiberglass. To support comfort and satisfaction when using the swimming pool, the adequate water level in the swimming pool will be maintained by system with several supporting devices such as pumps, dirt filters and maintained at a certain level. Other things that support water quality include temperature, water turbidity, color, odor, pH, chlorine content etc.