Impact of the Condition of Drinking Water Supply Networks on the Quality of Water Intended for Consumption: The Case of the Network in the Commune of Daloa (Central West of Côte d’Ivoire)

The potability of drinking water depends not only on the source and the treatment system, but also on the quality of the waterworks. In fact, the quality of drinking water is considerably degraded by the dilapidated state and lack of maintenance of drinking water networks. In Côte d’Ivoire, the majority of drinking water networks in the various towns are ageing. In Daloa, despite the efforts made by the company in charge of water treatment and distribution to make the water drinkable, the water at consumers’ taps is often colored, has an unpleasant aftertaste and settles after collection. As a result, people are concerned about the potability of tap water, and some are turning to alternative sources of drinking water of unknown quality. In order to determine the factors responsible for the deterioration in water color and taste, as well as the sectors of the network most affected, a diagnosis of the network’s equipment was carried out. Water samples taken from the network were analyzed for color and turbidity. The diagnosis revealed that most of the equipment (suction pads, valves, drains and fire hydrants) is outdated and irregularly maintained. Analyses show that the water is more colored in cast-iron and PVC pipes than in asbestos cement pipes. Coloration values in the network range from 0 to 27 UVC for asbestos cement pipes, from 15 to 56 UCV for ductile iron pipes, and from 11 to 102 UCV for PVC pipes. On the over hand, turbidity values vary from 8.02 to 3.32 NTU for ductile cast iron pipes, 8.51 to 16.98 NTU for asbestos cement pipes and 0.9 to 6.98 NTU for PVC pipes. Old cast-iron pipes release ferric ions on contact with water, degrading their color. Old cast-iron pipes release ferric ions into the water, degrading its color. The high color values observed in the vicinity of drains are thought to be due to irregular maintenance of the network. In fact, after network maintenance, a reduction rate ranging from 2% to 73% is observed for turbidity, while for color, the rate varies from 5% to 72%. In short, the network’s obsolescence and irregular maintenance contribute significantly to the deterioration of water quality.

Water Supply Networks as Cyber-physical Systems and Controllability Analysis

Cyber-physical systems(CPS) is a system of systems which consists of many subsystems that can stand alone in an individual manner and can be taken as a typical complex network.CPS can be applied in the critical infrastructures such as water supply networks,energy supply systems,and so on.In this paper,we analyze the structure of modern city water supply networks from the view of CPS theory,we use complex network theory to build an undirected and unweighted complex network model for the water supply networks to investigate the structural properties,and present the structure of the water supply networks and detect communities by a spectral analysis of the Laplacian matrix.Then,we analyze the structure and controllability of water supply networks by the structural controllability method.The results show the feasibility and effectiveness of the proposed complex network model.

Serviceability evaluation of water supply networks under seismic loads utilizing their operational physical mechanism

The serviceability of water supply networks(WSNs)under seismic loads has significant importance for estimating the probable losses and the impact of diminished functionality on affected communities.The innovation presented in this paper is suggesting a new strategy to evaluate the seismic serviceability of WSNs,utilizing their operational physical mechanism.On one hand,this method can obtain the seismic serviceability of each node as well as entire WSNs.On the other hand,this method can dynamically reflect the propagation of randomness from ground motions to WSNs.First,a finite element model is established to capture the seismic response of buried pipe networks,and a leakage model is suggested to obtain the leakage area of WSNs.Second,the transient flow analysis of WSNs with or without leakage is derived to obtain dynamic water flow and pressure.Third,the seismic serviceability of WSNs is analyzed based on the probability density evolution method(PDEM).Finally,the seismic serviceability of a real WSN in Mianzhu city is assessed to illustrate the method.The case study shows that randomness from the ground motions can obviously affect the leakage state and the probability density of the nodal head during earthquakes.

Functionality analysis of an urban water supply network after strong earthquakes

An urban water supply network(WSN)is a crucial lifeline system that helps to maintain the normal functioning of modern society.However,the hydraulic analysis of a significantly damaged WSN that suffers from pipe breaks or leaks remains challenging.In this paper,a probability-based framework is proposed to assess the functionality of WSNs in the aftermath of powerful earthquakes.The serviceability of the WSN is quantified by using a comprehensive index that considers nodal water flow and nodal pressure.This index includes a coefficient that reflects the relative importance of these two parameters.The demand reduction(DR)method,which reduces the water flow of nodes while preventing the negative pressure of nodes,is proposed.The difference between the negative pressure elimination(NPE)method and the DR method is discussed by using the example of a WSN in a medium-sized city in China.The functionality values of the WSN are 0.76 and 0.99 when nodal pressure and nodal demands are used respectively as the index of system serviceability at an intensity level that would pertain to an earthquake considered to occur at a maximum level.When the intensity of ground motion is as high as 0.4 g,the DR method requires fewer samples than the NPE method to obtain accurate results.The NPE method eliminates most of the pipes,which may be unrealistic.

Analytic Hierarchy Process(AHP)to Optimize the Service in a Water Supply Network

Decision making in drinking water supply networks is increasingly complex due to the large number of variables involved.In order to make better decisions it is necessary to use adequate and robust methodologies.This paper presents the application of the Analytic Hierarchy Process(AHP)related to the operation of the drinking water supply network of the city of Chihuahua,Mexico,where two possible alternatives are delineated with the objective to optimize the service.The application of AHP was carried out in 24 sectors that have substantial differences in their efficiency but with instrumentation and measurement in all the variables contemplated by the operating agency,with a population of 221,722 inhabitants which represent a 30%of the total population of the city,the results indicate that the best alternative is the one with less criteria to be controlled and fewer repercussions on the cost of operation and investment in the rehabilitation and replacement of the network.

Seismic vulnerability assessment of water supply network in Tianjin, China

The water supply network （WSN） system is a critical element of civil infrastructure systems. Its complexity of operation and high number of components mean that all parts of the system cannot be simply assessed. Earthquakes are the most serious natural hazard to a WSN, and seismic risk assessment is essential to identify its vulnerability to different stages of damage and ensure the system safety. In this paper, using a WSN located in the airport area of Tianjin in northern China as a case study, a quantitative vulnerability assessment method was used to assess the damage that the water supply pipelines would suffer in an earthquake, and the finite element software ABAQUS and fuzzy mathematic theory were adopted to construct the assessment method. ABAQUS was applied to simulate the seismic damage to pipe segments and components of the WSN. Membership functions based on fuzzy theory were established to calculate the membership of the components in the system. However, to consider the vulnerability of the whole system, fuzzy cluster analysis was used to distinguish the importance of pipe segments and components. Finally, the vulnerability was quantified by these functions. The proposed methodology aims to assess the performance of WSNs based on pipe vulnerabilities that are simulated and calculated by the model and the mathematical method based on data of damage. In this study, a whole seismic vulnerability assessment method for a WSN was built, and these analyses are expected to provide necessary information for a mitigation plan in an earthquake disaster.

Supply Chain Network Equilibrium with Revenue Sharing Contract under Demand Disruptions

Contract is a common and effective mechanism for supply chain coordination,which has been studied extensively in recent years.For a supply chain network model,contracts can be used to coordinate it because it is too ideal to obtain the network equilibrium state in practical market competition.In order to achieve equilibrium,we introduce revenue sharing contract into a supply chain network equilibrium model with random demand in this paper.Then,we investigate the influence on this network equilibrium state from demand disruptions caused by unexpected emergencies.When demand disruptions happen,the supply chain network equilibrium state will be broken and change to a new one,so the decision makers need to adjust the contract parameters to achieve the new coordinated state through bargaining.Finally,a numerical example with a sudden demand increase as a result of emergent event is provided for illustrative purposes.

Closed-loop supply chain network equilibrium strategy model with environmental protection objectives

With the increasing popularity of ecological civilization and sustainable development,enterprises should consider environmental protection measures in their operations in addition to pursue their economic interests.This paper establsihes a closed-loop supply chain network model composed of multiple suppliers,manufacturers,retailers,recyclers,and demand markets—regarding their dual goals of the profit maximization and the minimization of carbon emissions.The conditions necessary for establishing overall equilibrium and an equilibrium model of the entire closed-loop supply chain network are determined by applying variational inequality and dual theory.A modified projection contraction algorithm is used to design a model-solving program.Finally,using numerical examples,the paper conducts a comparative static analysis on important parameters such as the weight coefficients of environmental protection objectives and consumers'awareness of low-carbon environmental protection and attains some beneficial enlightenment on management.The results indicate that when the environmental protection objectives of a certain type of enterprise increases,both the economic benefits and environmental protection performance will improve;when the environmental protection objectives of all enterprises increases simultaneously,environmental protection performance improves significantly,but the changes in economic benefits of different enterprises are inconsistent and profit coordination is more complex.Although consumers’awareness of low-carbon preference could improve environmental performance,it reduces the overall profits of network members and the entire closed-loop supply chain network as a whole.The above conclusions can be used as a reference for the government in designing low-carbon environmental protection policy and in closed-loop supply chain research.

ZTE to Supply Bearer Network Solution to Finnet Group

ZTE Corporation, a leading global provider of telecommunications equipment and network solutions, announced an agreement with Westlink part of the Finish telecommunications group Finnet, to supply a unified multi-service metro bearer solution on February 18, 2010.

Supply Community Network:A Taxonomy of Flow Dimensions

Supply chain management(SCM)and its associated activities continue to evolve as new communication technologies and cooperative efforts emerge to facilitate system-wide process integration;the context within which supply chains(SCs)operate,the technologies,and performance enhancement mechanisms have all changed.Thus,linear-based SCs are increasingly being challenged as firms look towards a more networked approach to maximize performance amid growing market dynamics.This paper,however,recognizing inherent similarities between social structure of Social Internet of Things(SIoT)principles and what we term supply community networks(SCN)from literature,seeks to cross-pollinate the two in a way capable of dealing with these market dynamics.Our contribution is,therefore,a new‘setting’of social relationships between supply community agents(SCA)within SCN mirroring interactions played out in the physical world;SCAs autonomously sense each other,exchange information and interact within SCN mimicking the behavior of humans.Also,it identifies the bounds of flow,i.e.all possible dimensions within a SCN which need to be understood to support relationship management.Therefore,communications are improved,sharpening SCAs synchronization in a way responsive to customer needs.

Empirical topological investigation of practical supply chains based on complex networks

The industrial supply chain networks basically capture the circulation of social resource, dominating the stability and efficiency of the industrial system. In this paper, we provide an empirical study of the topology of smartphone supply chain network. The supply chain network is constructed using open online data. Our experimental results show that the smartphone supply chain network has small-world feature with scale-free degree distribution, in which a few high degree nodes play a key role in the function and can effectively reduce the communication cost. We also detect the community structure to find the basic functional unit. It shows that information communication between nodes is crucial to improve the resource utilization. We should pay attention to the global resource configuration for such electronic production management.

Predictive Zone Control of Pressure Management for Water Supply Network Systems

In this paper we address the problem of pressure management in water supply system （WSS） network. The model-based predictive control （MPC） strategies have some important features to deal with WSS. By hydraulic analysis of WSS, the predictive model is derived from the dynamic model and static model of WSS. Through WSS, the consumers＇ demands are required to be met at all times according to some operational constraints that must be satisfied. The constraints of flow through actuators, the water level of reservoirs and the consumer areas＇ pressure demand are determined by a specific system. In this work, we develop a constrained MPC controller that considers the zone control of the pressure outputs and incorporates steady state economic targets in the control cost function. The designed management strategies are applied to a case study and simulation results, covering different aspects, are provided. The output nodal pressure can be controlled in the desired zone by optimal scheduling the actuators of the WSS. If the variation range of reservoir＇s water level is broader, the rate of flow through the actuators is gentle, and vice versa.

Supply chain network design under uncertainty with new insights from contracts

In this paper, the classical problem of supply chain network design is reconsidered to emphasize the role of contracts in uncertain environments. The supply chain addressed consists of four layers: suppliers, manufacturers, warehouses, and customers acting within a single period. The single owner of the manufacturing plants signs a contract with each of the suppliers to satisfy demand from downstream. Available contracts consist of long-term and option contracts, and unmet demand is satisfied by purchasing from the spot market. In this supply chain, customer demand, supplier capacity, plants and warehouses, transportation costs, and spot prices are uncertain. Two models are proposed here: a risk-neutral two-stage stochastic model and a risk-averse model that considers risk measures. A solution strategy based on sample average approximation is then proposed to handle large scale problems. Extensive computational studies prove the important role of contracts in the design process, especially a portfolio of contracts. For instance, we show that long-term contract alone has similar impacts to having no contracts, and that option contract alone gives inferior results to a combination of option and long-term contracts. We also show that the proposed solution methodology is able to obtain good quality solutions for large scale problems.

SUPPLY CHAIN OPTIMIZATION IN CONTEXT OF PRODUCTION FLOW NETWORK

For large multinational companies, the complex production process of their finished goods usually contains plenty of stages, which constitute a production flow network. Each production stage in the production flow network can be undertaken by one or more suppliers. This study proposes a stochastic programming model for the production flow network oriented supply chain network design problem, which optimizes the decision of allocating stages to suppliers with the objective of minimizing the total expected costs of production and transportation among suppliers under uncertain demands of customers. A local branching based solution method is developed to solve the model. A case study on applying this model to a large automobile company is performed. In addition, some numerical experiments are conducted to validate the effectiveness of the proposed model and the efficiency of the proposed solution method.

Strategy Selection of Production Technical Standards in a Manufacturing Supply Chain Network： The Role of Partnership Density

This paper presents the game of production technical standards between downstream and upstream suppliers on a manufacturing supply chain network when the two parties have different partnership densities, namely, the numbers of replaceable and mature manufacturing partners. We firstly constructed a manufacturing chain network and analyzed its three relationship structures among suppliers with the presence of different relationship densities, and found that all the three relationships brought about the game of production technical standards between partnership-rich and partnership-scanty suppliers. Then we built a two-party payoff matrix, and analyzed the two-party game and evolutionary stable strategy, based on replication dynamic equation and asymmetric evolutionary game theory. The evolutionary stable strategies of two parties under varying payoff parameters were validated through numerical simulation. Finally, we proposed some suggestions for both those manufacturers with more partners and fewer partners, respectively.

A case study on sample average approximation method for stochastic supply chain network design problem

This study aims to solve a typical long-term strategic decision problem on supply chain network design with consideration to uncertain demands. Existing methods for these problems are either deterministic or limited in scale. We analyze the impact of uncertainty on demand based on actual large data from industrial companies.Deterministic equivalent model with nonanticipativity constraints, branch-and-fix coordination, sample average approximation(SAA) with Bayesian bootstrap, and Latin hypercube sampling were adopted to analyze stochastic demands. A computational study of supply chain network with front-ends in Europe and back-ends in Asia is presented to highlight the importance of stochastic factors in these problems and the efficiency of our proposed solution approach.

Industry 4.0: Revolution or Evolution?

“Industry 4.0” term is devoted to the fourth industrial revolution. Over time and by developing different technologies, this term is coming with the new paradigm and technologies, which help to connect the machines, products, and methods as an interconnected system. This paper aims to introduce an analysis and a reflection around the concepts industry 4.0 and their impacts in the actual industrial world. The effects of this digitalization will be investigated on supply chain systems, decision-making processes, and business models. The classic supply chain is evolving into a Network Supply System (NSS) that is an interconnected supply chain with more focus on product and customer expectations. The global value chain process tends to be product-oriented. Smart data make the decisions more dynamic, flexible, and precise. Therefore, every industrial sector has to be adapted to this digital transformation in all aspects. However, the environmental aspects, global warming, and human healthcare issues are the challenge facing industries and human life, which can be like a brake to make efforts to improve digital life and machine technicity. This paper tries to produce a critical analysis of the concept “industry 4.0 revolution” based on different guidelines to show that it is an evolution of the industry coming through the development of several technologies.

GLOBAL MANUFACTURING VIRTUAL NETWORK (GMVN): A REVISITING OF THE CONCEPT AFTER THREE YEARS FIELDWORK

The idea of the global manufacturing virtual network (GMVN) was introduced in 2000 in order to highlight an emerging as well as an alternative manufacturing system which will have strong impacts on industry and implications to management theory. During the last three years, more than thirty companies - based in the electronics, bio-pharmaceuticals, garment, and home electronics appliance industries - have been studied in the UK and China. The research project addresses the emergence of the collaborative manufacturing phenomenon at three levels - sector, system and enabling technology. This paper summarises preliminary research findings from fieldwork conducted over the last three years. It seeks to clarify the characteristics and functionality of GMVN through the case studies and to contrast it to other types of business model, such as the multinational corporations (MNC) and international strategic alliances (ISAs). It also raises some new research questions and themes for further research into GMVN.