An integrated DEMATEL and system dynamic model for project cost prediction

Actual cost fluctuations in construction projects are common in the construction industry, including the Kingdom of Saudi Arabia (KSA). This study's objective is to establish a simulation forecasting model for Saudi projects' cost changes that will be used to anticipate the actual cost spent at the project's end. It also indicates if there are cost overruns or savings by considering ten identified cost-risk impact factors. The study involves a systematic, integrated approach to developing system dynamics (SD) to reflect the ten cost overrun impact factors (COICs) in the KSA construction industry. Thus, the Decision-Making Trial and Evaluation Laboratory (DEMATEL) technique aids in evolving a Causal Loop Diagram (CLD) in the SD modeling stages. After performing the consistency and extreme tests, the model is verified by being applied in two case studies (an academic building and an infrastructure project) in Riyadh City, KSA. The main findings reveal that the model provided cost savings for the first and second case studies of 4.8% and 3.76%, respectively. Different experts have evaluated the developed dynamic system. According to the experts who support the developed model, the model is applicable if the contractor has a reasonable profit margin. In contrast, opponents' experts noted that the system still generates a profit margin despite change orders and project delays. The main conclusion that the experts recognize is that the approach successfully considered the relationships between the influencing factors. The findings can be utilized to create an integrated conceptual framework for construction management, which could result in a rapid and profitable project launch.

Systematically assess the advancing and limiting factors of using the multi-soil-layering system for treating rural sewage in China: From the economic, social, and environmental perspectives

Solving the problem of rural sewage is considered an essential task in China's rural revitalization strategy. Based on the yearbook data of sewage treatment in rural areas between 2014 and 2019, although the rate of sewage treatment in rural areas of China showed an upward trend, it was still below 35%, mainly due to the lack of suitable sewage treatment technologies. Here, we discuss the multi-soil-layering (MSL) system, which is an emerging technology suitable for rural sewage treatment. It was deemed to overcome the shortcomings of current biological and ecological treatment technologies, such as complex operation, large area, and high operating costs. We used system dynamics to evaluate the advancing and limiting factors of MSL application for rural sewage treatment from the social, environmental, and economic dimensions. The results illustrated a complete causal loop diagram in which essential variables and relationships were concentrated in the technology, operation and maintenance, and satisfaction of farmers. The efficiency of MSL is the key variable affecting the final decision of the MSL application. Overall, using MSL to treat rural sewage could be an option to improve the rural environment in China. However, the scientific technological model for MSL should be further explored. This review provides guidance on how to promote MSL systems in rural areas.

Nursing manpower forecast for cancer patients

BACKGROUND AND OBJECTIVES

This paper presents a dynamic model aimed at predicting nursing manpower requirements for cancer care over the next ten years. The proposed model, based on the Taiwan Health Insurance Database (2000 to 2010), is meant to serve as a reference in establishing policy for government health units.

METHODS

The proposed prediction model uses fuzzy sets to replace definite values with interval values in order to account for uncertainties in real-world data and enhance the flexibility of prediction results.

RESULTS

Our results suggest that the demand for nursing manpower for cancer care will grow steadily in the foreseeable future. The gap between the demand for nursing staff and the supply is expected to peak in 2027. By then, the number of oncologists is expected to reach 7,083 (54.32% of the total number of in-hospital physicians), but the number of oncology nurses will be less than 26,297 (56.5% of the total healthcare manpower). It is also expected that there will be fewer than 1,613 outpatient physicians (71.81% of the total number of physicians) and fewer than 4,967 outpatient nurses (68.46% of the total nursing manpower).

CONCLUSIONS

This paper provides a valuable reference for government agencies involved in the nursing manpower planning to improve the quality of nursing care.

An integrated approach to investigate the relationship of coupling coordination between social economy and water environment on urban scale - A case study of Kunming

With a rapid economic growth and social development in China, the associated problems of water pollution and shortage of water resources would limit the sustainable and coordinated development of socioeconomic and water environmental systems of urban cities. To investigate the relationship of coupling coordination between social economy and water environment on urban scale, we introduced an integrated approach that enables the dynamic evaluation of coupling coordination degree (CCD), which consists of a system dynamics model and a coupling coordination degree model; and applied it to a case study in Kunming in 2016-2025. The business-as-usual (BAU) scenario and five alternative regulating scenarios are simulated to evaluate the effectiveness exerted by various socioeconomic development patterns and water protection efforts in improving CCD. We found that the improvement of CCD could attribute to both the sufficient water protection efforts and the maintaining sustainable speed and scale of socioeconomic development patterns. Under BAU scenario, Kunming would maintain the current state of barely balanced development with CCD at 0.5-0.8, predominantly due to substantial water consumption and pollution. Through the comparison of dynamic evolutions of system indicators and CCD under five alternative regulating scenarios, it is realistic for Kunming to plan its future development in accordance to M-H scenario (Medium-speed socioeconomic development pattern; High-intensity water protection effort). Following this scenario, Kunming's CCD would conform to a steadily increasing trend in 2016-2025 and remain above 0.8 in 2022-2025, tracing a shift in the development stage of that coupling coordination from "barely balanced development" to "highly balanced development" despite the difficulty to cut NH₃-N emission significantly. The effective and feasible regulatory measures such as reducing productive or domestic water pollutants and consumptions; improving collection and reuse rates of wastewater, should be prioritized when adjusting coordination development during decision-making.

Dynamic patterns of overexploitation in fisheries

•

For the first time, the “predator-prey” model is used for the quantitative description of an economic predatory dynamic in real-world fisheries.

•

A simple “mind-sized” model highlights the driving forces that lead to the resources’ overexploitation and the collapse of a production system.

•

A renewable fish stock can behave as a non-renewable resource when exploited at a speed much higher than its carrying capacity.

•

Coupled feedback effects are the origin of overexploitation and collapse in real-world fisheries.

Understanding overfishing and regulating fishing quotas is a major global challenge for the 21st Century both in terms of providing food for humankind and to preserve the oceans’ ecosystems. However, fishing is a complex economic activity, affected not just by overfishing but also by such factors as pollution, technology, financial factors and more. For this reason, it is often difficult to state with complete certainty that overfishing is the cause of the decline of a fishery. In this study, we developed a simple dynamic model specifically designed to isolate and to study the role of depletion on production. The model is based on the well-known Lotka-Volterra model, or Prey-Predator mechanism, assuming that the fish stock and the fishing industry are coupled variables that dynamically affect each other. In the model, the fishing industry acts as the “predator” and the fish stock as the “prey”. If the model can fit historical data, in particular relative to the productive decline of specific fisheries, then we have a strong indication that the decline of the fish stock is driving the decline of the fishery production. The model doesn’t pretend to be a general description of the fishing industry in all its varied forms; however, the data reported here show that the model can describe several historical cases of fisheries whose production decreased and collapsed, indicating that the overexploitation of the fish stocks is an important factor in the decline of fisheries.

Operationalizing safe operating space for regional social-ecological systems

This study makes a first attempt to operationalize the safe operating space concept at a regional scale by considering the complex dynamics (e.g. non-linearity, feedbacks, and interactions) within a systems dynamic model (SD). We employ the model to explore eight 'what if' scenarios based on well-known challenges (e.g. climate change) and current policy debates (e.g. subsidy withdrawal). The findings show that the social-ecological system in the Bangladesh delta may move beyond a safe operating space when a withdrawal of a 50% subsidy for agriculture is combined with the effects of a 2°C temperature increase and sea level rise. Further reductions in upstream river discharge in the Ganges would push the system towards a dangerous zone once a 3.5°C temperature increase was reached. The social-ecological system in Bangladesh delta may be operated within a safe space by: 1) managing feedback (e.g. by reducing production costs) and the slow biophysical variables (e.g. temperature, rainfall) to increase the long-term resilience, 2) negotiating for transboundary water resources, and 3) revising global policies (e.g. withdrawal of subsidy) that negatively impact at regional scales. This study demonstrates how the concepts of tipping points, limits to adaptations, and boundaries for sustainable development may be defined in real world social-ecological systems.