Search Results (11)

Preventive Maintenance (PM) is a periodic maintenance strategy that has great results for devices in extending their lives, increasing productivity, and, most importantly, helping to avoid unexpected breakdowns and their costly consequences. Preventive maintenance scheduling (PMS) is determining the time for carrying out PM, and it represents a sensitive issue in terms of impact on production if the time for the PM process is not optimally distributed. This study employs hybrid heuristic methods, integrating Genetic Algorithm (GA) and Tabu Search (TS), to address the PMS problem. Notably, the search for an optimal solution remained elusive with GA alone until the inclusion of TS. The resultant optimal solution is achieved swiftly, surpassing the time benchmarks set by conventional methods like integer programming and nonlinear integer programming. A comparison with a published article that used metaheuristics was also applied in order to evaluate the effectiveness of the proposed hybrid approach in terms of solution quality and convergence speed. Moreover, sensitivity analysis underscores the robustness and efficacy of the hybrid approach, consistently yielding optimal solutions across diverse scenarios. The schedule created exceeds standards set by waterworks experts, yielding significant water and electricity surpluses—16.6% and 12.1%, respectively—while simultaneously matching or surpassing total production levels. This method can be used for power plants in private or public sectors to generate an optimal PMS, save money, and avoid water or electricity cuts. In summary, this hybrid approach offers an efficient and effective solution for optimizing PMS, presenting opportunities for enhancement across various industries. Full article

Renewable solar energy storage facilities are attracting scientists’ attention since they can overcome the key issues affecting the shortage of energy. A nanofluid phase change material (PCM) is introduced as a new sort of PCM is settled by suspending small proportions of nanoparticles in melting paraffin. ZnO/α-Fe₂O₃ nanocrystals were prepared by a simple co-precipitation route and ultrasonically dispersed in the paraffin to be a nanofluid-PCM. The behaviors of the ZnO/α-Fe₂O₃ nanocrystals were verified by X-ray diffraction (XRD) analysis, and the average particle size and the morphology of the nanoparticles were explored by transmission electron microscopy (TEM). For the object of industrial ecology concept, aluminum-based waste derived from water-works plants alum sludge (AS) is dried and augmented with the ZnO/α-Fe₂O₃ nanocrystals as a source of multimetals such as aluminum to the composite, and it is named AS-ZnO/α-Fe₂O₃. The melting and freezing cycles were checked to evaluate the PCM at different weight proportions of AS-ZnO/α-Fe₂O₃ nanocrystals, which confirmed that their presence enhanced the heat transfer rate of paraffin. The nanofluids with AS-ZnO/α-Fe₂O₃ nanoparticles revealed good stability in melting paraffin. Additionally, the melting and freezing cycles of nanofluid-PCM (PCM- ZnO/α-Fe₂O₃ nanoparticles) were significantly superior upon supplementing ZnO/α-Fe₂O₃ nanoparticles. Nanofluid-PCM contained the AS-ZnO/α-Fe₂O₃ nanocrystals in the range of 0.25, 0.5, 1.0, and 1.5 wt%. The results showed that 1.0 wt% AS-ZnO/α-Fe₂O₃ nanocrystals contained in the nanofluid-PCM could enhance the performance with 93% with a heat gained reached 47 kJ. Full article

Industries worldwide have faced continuous burdens since the beginning of the COVID-19 pandemic, while adjusting to rapidly changing rules and regulations. Industries need to be prepared to remain operational and productive in the face of current and emergent pathogens. While several businesses could remain functional through remote work, critical industries faced closings, worker shortages, and loss of productivity. Pharmaceutical industries were blessed with an increase in the stock market and creation of new jobs, but faced serious severe challenges due to shortage of medicines and drugs. Critical infrastructures such as healthcare, food and agriculture, manufacturing, construction, transportation, retail, waterworks, and waste management took a significant hit during the pandemic, and are still suffering from worker shortages to function optimally. Above all odds, companies were able to maintain the necessities by implementing strict safety protocols such as thorough and repeated cleaning, use of hand sanitizer/disinfectants, wearing face masks and personal protective equipment, and maintaining social distancing. This article addresses how COVID-19 disrupted normal operations on a large scale, and how essential businesses have learned to assess the impact, handle situations effectively, and become resilient for future crises. Best practices were tailored to each industry sector to prepare for and address the pandemic. Full article

Multi-regional waterworks are large-scale facilities for supplying tap water to the public and industrial parks, and interruptions in the water supply due to leaks result in massive social and economic damages. Accordingly, real-time, around-the-clock accident monitoring is necessary to minimize secondary damage. In the present study, a section of a large-scale waterworks transmission mains system with frequent changes in its physical boundaries was defined for sensor network map-based deep learning input and output. A deep neural network (DNN)-based pressure prediction model, able to detect pipe burst accidents in real-time using short-term data collected over periods within 1 month, was developed. A sensor network map refers to a sensor-based hierarchy diagram, which is expressed using a hydraulically divided area. A hydraulically independent area can be determined using known value information (e.g., the known flow, pressure, and total head) in a complex water supply system. The input data used for the deep learning model training were: the water levels measured at 1 min intervals, flow rates, ambient pressure, pump operation state, and electric valve opening data. To verify the developed methodology, two sets of real-world data from past burst accidents in different multi-regional waterworks systems were used. The results showed that the difference between the pressure as measured by pressure meters and an estimated pressure was extremely small before an accident, and that the difference would reach a maximum at the time point when an accident occurs. It was confirmed that an approximate estimation of an accident occurrence and accident location could be estimated based on predicted pressure meter data. The developed methodology predicts a mutual influence between pressure meters and, therefore, has the advantage of not requiring past data covering long time periods. The proposed methodology can be applied immediately and used in currently operational large-scale water transmission main systems. Full article

In South Korea, a reasonable rate system that can be domestically applied to calculate sewage and stormwater separately from the domestic sewage fee system is needed. This study proposed a phased pricing scenario to separate sewage and stormwater in Bupyeong-gu, Incheon, and the rate changes were compared based on a simulated calculation of the stormwater utility fee. In this investigation, stormwater runoff cases from other countries and the current domestic system were analyzed. A stormwater utility fee introduction scenario was presented that considers the impervious surface area. Water and sewage usage statistics and hydrant spatial data were collected from the Incheon Metropolitan City Waterworks Authority, and the total amount of water and sewage fees from the land use area were calculated. The stormwater utility fee was calculated, and the rates of each step were compared. The total sewage fee of Bupyeong-gu during 2014 was KRW 21,685,446,578, and the phased stormwater utility fee was calculated, assuming that 40% represents the stormwater cost. The sewage fee for the residential area in phase 3 decreased by 0.77% compared to phase 1. For the commercial areas, the sewage fee decreased by 36.87%. Because the impervious surface ratio was high, the overall area contributing to the impervious surface area was small. In the industrial area, the sewage fee increased by 8.35%. In the green area, the sewage fee increased by 37.46%. The sewage fee for the apartment complexes decreased by 10.6%. Finally, the possibility of estimating the actual stormwater utility fee was confirmed. Full article

The degradation of densely populated river delta environments due to the accelerating rise in sea level can affect the availability of freshwater for municipal supplies, irrigation, and industrial use. A fully calibrated three-dimensional numerical model is used in this study to evaluate the threat posed by the sea-level rise, which predicted to occur by 2100, to freshwater resources in the upper tributaries of Pearl River Estuary. The results indicate that both the intensity and duration of dry-season saltwater intrusion greatly increase as the sea level rises, making the water at drinking-water intake stations for the four waterworks no longer suitable for municipal supply. Flow modulation is performed to identify the threshold at which saltwater intrusion could be effectively suppressed in response to both sea-level rise and dry season hydrodynamics. The number of days for which water meets the drinking-water standard decreases as the sea level rises, but increases with increased river flow. The combined effect of future drought and sea-level rise would further limit the availability of freshwater in the upper tributaries. Stronger upstream salinity transport during flood tide are found in the sea-level rise case. The increased flood tidal salinity transport would have great impact on the tidal freshwater wetlands. Full article

Ttukdo Water Purification Plant, built in 1908, is the first modern waterworks facility in Seoul and the first waterworks industrial heritage in Korea. Modern waterworks were established in order to resolve insanitary conditions of the city as a part of modernization projects; however, it had been developed with discrimination and colonial domination under Japanese occupation. This paper investigates how Ttukdo Water Purification Plant, a product of colonial modernity, became the representative modern waterworks heritage in both aspects of a colonial and civil engineering heritage. Based on archival research, this study analyzes the transformation process of Ttukdo Water Purification Plant, and the changing meaning and value with the historical background. As a result, Ttukdo Water Purification Plant has been characterized by the universal features of water industry heritage, continuity as a facility to produce clean water, and symbolic meaning as the guardian of urban sanitation. On the other hand, Ttukdo plant is regarded as a monument which was conceived under complicated historical conditions—at the confluence of modernization, colonial rule, and emergent urban needs. Full article

Groundwater protection, which is effected by multiple actors at multiple levels using multiple instruments, is commonly termed “groundwater governance”. Although the concept has attracted increasing attention since the 1990s, several of its associated measures remain to be fully implemented. Most are still inchoate strategies and improvement is expected to be a gradual, long-term process. The Gakunan Council for Coordinated Groundwater Pumping (CCGP), which was established, in 1967, in Fuji City in Japan’s Shizuoka Prefecture, is an exceptional case. The Gakunan CCCP was created to deal with a common-pool resource problem where massive groundwater pumping caused seawater intrusion in the city’s coastal area due to the low cost of extraction and incomplete groundwater ownership. The Gakunan CCCP succeeded in recovering elevation of groundwater tables by connecting efforts between the public and private sectors, including information sharing, legal authority to regulate groundwater, investment in alternative water supplies, internal subsidies between groundwater users, and charge for water disposal. Previous studies have iterated that the fostering of participation from various stakeholders and dividing labor between them appropriately are key elements of successful groundwater governance. This paper investigates these factors, explores the importance of the metagovernor as coordinator, and offers a fresh perspective on the significance of groundwater governance. Full article

Water supply facilities such as waterworks systems are facilities that supply residential and industrial water essential for humans to live and it is essential for these facilities to be prepared for earthquake hazards. In the present study, new hydraulic analysis procedures that can complement problems in existing model were proposed for performance quantification under seismic hazards. Detailed procedures for estimating the serviceability of water supply networks using pressure dependent demand (PDD) and pressure dependent leakage (PDL) techniques were proposed. The developed methodologies can simulate many pipe leakage and breakage situations more realistically. The methodologies were applied to representative pipe networks to investigate the models and new performance quantification indicators were additionally presented. The developed models are judged to be usable as a basic tool finding for guidelines because they can simultaneously quantify the amount of leakage calculated from the viewpoint of suppliers as well as the water availability of consumers when an earthquake hazard has occurred. Full article

The aim of this paper is to present the evolution of aqueduct technologies through the millennia, from prehistoric to medieval times. These hydraulic works were used by several civilizations to collect water from springs and to transport it to settlements, sanctuaries and other targets. Several civilizations, in China and the Americas, developed water transport systems independently, and brought these to high levels of sophistication. For the Mediterranean civilizations, one of the salient characteristics of cultural development, since the Minoan Era (ca. 3200–1100 BC), is the architectural and hydraulic function of aqueducts used for the water supply in palaces and other settlements. The Minoan hydrologists and engineers were aware of some of the basic principles of water sciences and the construction and operation of aqueducts. These technologies were further developed by subsequent civilizations. Advanced aqueducts were constructed by the Hellenes and, especially, by the Romans, who dramatically increased the application scale of these structures, in order to provide the extended quantities of water necessary for the Roman lifestyle of frequent bathing. The ancient practices and techniques were not improved but survived through Byzantine and early medieval times. Later, the Ottomans adapted older techniques, reintroducing large-scale aqueducts to supply their emerging towns with adequate water for religious and social needs. The scientific approach to engineering matters during the Renaissance further improved aqueduct technology. Some of these improvements were apparently also implemented in Ottoman waterworks. Finally the industrial revolution established mechanized techniques in water acquisition. Water is a common need of mankind, and several ancient civilizations developed simple but practical techniques from which we can still learn. Their experience and knowledge could still play an important role for sustainable water supply, presently and in future, both in developed and developing countries. Full article

From the viewpoint of combating global warming in Japan, measures to reduce emissions from the activities involved in daily life have been accelerated in concurrence with the efforts made in the industrial sector to save energy. As one such measure, the reduction of energy consumption in waterworks and sewer systems by reducing the volume of water used in the housing sector is gaining attention; measures for the conversion of water saving into CO₂ reduction credit in the domestic credit system are also being examined. To address the credit development for CO₂ reduction by water saving, it was necessary to determine the CO₂ emission factor for water. Hence, we calculated the CO₂ emission factor of water use in Japan and determined the value to be 0.376 kg CO₂/m³ which applied the generating end electricity value. In addition, since electricity contributes to 90% of the energy consumption of the waterworks and sewer systems of Japan and since the emission factor for electricity changes with the power source composition ratio, the CO₂ emission factor for water also needs to be updated to match the emission factor for electricity. We therefore developed a calculation equation for updating this emission factor. Full article