Detailed Network Design Research Articles

Clustering and optimising regional segregated resource allocation networks

Policymakers and officials worldwide are making more stringent environmental norms and waste disposal policies to encourage industries to move towards cleaner production. One of the main challenges that industries face moving towards cleaner production is the adoption of different strategies for optimising their resource utilisation and waste reduction economically. This is particularly challenging for large-scale industries or a group of industrial plants located in an industrial region. This paper presents a novel approach to economic resource optimisation focussed mainly on large-scale industries, different industrial plants located in the vicinity of each other, or an industrial symbiosis network. In this work, a clustering algorithm is developed to segregate the given plants into different clusters based on the concept of load deficits and surpluses of each plant. The concept ideally allows only the plants with surpluses to send out their unused sources and plants with deficits to only receive external sources/resources. The clusters are formed based on the distances between plants, which in turn helps in saving transportation and communication costs. The clustered plants are then easy to optimise and manage for resource and cost optimality. The applicability of the proposed clustering algorithm is demonstrated using two case studies from the domain of water recycling networks containing multiple contaminants with detailed network design, highlighting the importance of clustering in an industrial symbiosis network. It is observed that directing the excess flows from one plant to other plants in the same cluster can save a considerable amount of fresh resources. It implies that in the broader aspect, the developed methodology can address the optimisation of economic resources and can aid in the better management of overall resources for a large-scale industrial symbiosis network.

Combined Hub Location and Service Network Design Problem: A Case Study for an Intermodal Rail Operator and Structural Analysis

In intermodal transportation, hubs are facilities that perform switching, sorting, connecting, and consolidating functions between many origins and destinations. Hub location problems (HLP) accordingly involve the location of hubs but include abstract network design decisions as well. In the past, the strategic location decision and the more tactical network design decision, in the form of a service network design problem (SNDP), have been considered separately. However, the SNDP is based on an existing hub network and the HLP could benefit from a more detailed network design. For this reason, this paper presents the combined hub location and service network design problem (C-HL-SNDP), which considers the strategic and tactical planning dimensions in an integrated manner. In a case study of a German intermodal operator, the paper shows that integrated modeling can be used to produce very good and realistic solutions that generate added value. The combined model with a classical HLP approach is compared and a structural analysis of the solution properties is performed. With this, it can be shown that the different consideration of economies of scale and economies of density lead to fundamentally different solutions.

Simultaneous Water and Energy Saving in Cooling Water Networks Using Pinch Approach

Abstract Recirculating cooling water system is the most common practice used for rejection of waste heat to environment. The fresh cooling water is distributed directly without reuse via a heat exchanger networks in parallel configuration to provide cooling duties for hot process stream. Under this configuration, thewater returns to cooling tower with high heat capacity flow rate and low temperature. These conditions will lead to poor performance of cooling tower.In this paper, process integration approach based on Pinch analysis technique used to address energy efficiency issues in cooling water networks for retrofit design problem. The Demand-Composite Analysisis an analytical approach requiring no graphical procedures developed in this work to target simultaneously, prior to the detailed network design, the minimum heat capacity flow rate of fresh cooling water and the maximumtemperature of waste cooling water to maximize the efficiency of cooling tower.The key basis for this methodology is the conversion of the cooling duties to its equivalent demand and source pairs.Agraphical representation called Demand-Composite Curveis then generated to understand the targeting philosophy. To synthesize a network that achieves the target values, the construction ofTemperature Diagram is also proposed as a design methodology for maximum reuse of cooling water.A case study is treated to illustrate the practicability of this approach.

Development of an Integrated Technique for Energy and Property Integration in Batch Processes

This paper presented a new technique for targeting minimum total annual cost of property-based heat integrated resource conservation networks (HIRCNs) for batch processes. This new technique takes in consideration of simultaneously heat and property integration with an objective to minimize the usage of fresh resources and energy utilities prior to the detailed network design. It is formulated as a mixed integer nonlinear programming (MINLP) mathematical model for HIRCNs which consists of property-based resource conservation network (RCN) and heat exchanger network (HEN) models. The property-based RCN model is formulated based on a supertargeting approach while the HEN model is developed via automated targeting approach. Two case studies were used to demonstrate the proposed model’s applicability and advantages. Moreover, comparisons of the results for the proposed model for HIRCN with storage system and without storage system as well as sequential targeting approach are also addressed.

A new methodology for the synthesis of an optimum flexible water networks

This paper presents a new optimization model for the synthesis of direct reuse/recycle water networks with data uncertainties. In this case, data uncertainties were originated from the varying parameters of the water sources and sinks, which fluctuate within a given range of values. The aim of the method is to design an optimum flexible water network (FWN) that ensures minimum fresh water consumption and yet fulfilling all process constraints and uncertain parameters. The resulting FWN also features the minimum number of pipelines, which will ease process operation and control. Due to the complexity of the problem, multistep solving method based on theorem of corner points has been developed. The FWN obtained using the proposed method also includes information on the maximum flow rate in the pipelines, which is essential for detailed network design stage. The resulting model is a mixed integer linear problem (MILP), which may be solved to obtain global optimum solution. Two case studies were used to elucidate the newly proposed method.

Systematic Optimization of Heat-Integrated Water Allocation Networks

This paper deals with the design of heat integrated water utilization networks. The nonisothermal mixing and freely splitting nature of hot and cold streams have made the problem far more complicated than the design of heat exchanger networks (HEN). By establishing an MILP model, promising heat exchange matches between hot and cold streams are obtained first without considering the detailed network design. Subsequently, a stage-wise HEN superstructure is introduced for the detailed network design. The proposed systematic approach can be applied for large scale problems. Examples from literature and a practical example in a PVC plant are used to illustrate the applicability of the approach.

Value recovery network design for product returns

PurposeThe purpose of this paper is to use a conceptual model from literature for designing value recovery (VR) networks for three categories of post‐consumer product returns.Design/methodology/approachA bi‐level optimization model is developed to determine the disposition decision for refrigerators, washing machines and passenger cars in the Indian context using data for product returns from literature. Using standard off‐the‐shelf software, the break‐even values of returns are calculated for setting up various VR facilities under different scenarios to maximize profits for a ten‐year time‐horizon.FindingsThe VR activities are profitable for all the three categories of products beyond a certain minimum quantity of returns. Experimentation across the three product categories shows that presently remanufacturing is not a viable economic proposition in the Indian context. Further, the VR network design suggested by this approach is volume flexible.Research limitations/implicationsA “push” system where the volumes and grades of returns drive the VR decisions. Optimization has been carried out for three product categories and not brands or OEMs. No free choice of facility locations.Practical implicationsThe insights and learning under different scenarios may be utilized as inputs for decision‐making and for designing various incentive plans.Originality/valueThis work is a first step towards VR network design in the Indian context. Various tools from the methodological perspective are used and provide detailed network design from the topological perspective.

Design Methodology for Flexible Multiple Plant Water Networks

This paper deals with the design of flexible multiple plant water networks. Some practical features of multiple plant integration such as operating flexibility and expensive operating cost have made the number of cross plant interconnections (CPIs) an important parameter of water minimization problem. By combining pinch insight with mathematical programming, target freshwater usage and CPI conditions are obtained first without considering the detailed network design. Subsequently, an MILP model is established for the design of flexible water networks of individual plants. The proposed systematic approach can be applied for both fixed contaminant (FC) operations and fixed flow rate (FF) operations, limited to a single contaminant. An example from literature and a practical example of a chlor−alkali complex are used to illustrate the applicability of the approach.

Architectural Design of Next-Generation Science Information Network

This paper proposes an advanced hybrid network architecture and a comprehensive network design of the next-generation science information network, called SINET3. Effectively combining layer-1 switches and IP/MPLS routers, the network provides layer-1 end-to-end circuit services as well as IP and Ethernet services and enables flexible resource allocation in response to service demands. The detailed network design focuses on the tangible achievement of providing a wide range of network services, such as multiple layer services, multiple virtual private network services, advanced qualities of service, and layer-1 bandwidth on demand services. It also covers high-availability capabilities and effective resource assignment in the hybrid network. The cost reduction effect of our network architecture is also shown in this paper.

Source composite curve for waste reduction

Waste reduction through source reduction and on-site recycling is an important aspect of pollution prevention . Techniques of process integration may be used for pollution prevention. In this paper an algorithmic procedure is presented to reduce waste generation through maximizing on-site reuse/recycling. The proposed methodology is based on the pinch principles and establishes a minimum waste generation target prior to the detailed network design. A new graphical representation called source composite curve, is utilized to understand the targeting philosophy. Minimum waste targeting algorithm is applied to address different problems such as water management, hydrogen management, as well as material reuse and recycling. Appropriate changes in a process or process modification can further reduce the waste generation. In this paper a methodology is presented to reduce waste generation through process modifications and it is demonstrated through an example.

Analysis and design of backbone architecture alternatives for IP optical networking

The unprecedented growth of IP traffic is leading Internet service providers and network operators worldwide to investigate architectural alternatives for cost effective, reliable, scalable, and flexible multiterabit IP backbones. In this paper, several overlay, service, and transport layer networking architectures, which employ IP, MPLS, SONET/SDH, and DWDM technologies, are proposed and analyzed. Multiple parameters, such as network capacity, cost, restoration strategy, reconfigurability, and accommodation of preemptable traffic, are considered for the architectural comparison. Detailed network design and economic analysis are provided for the different alternatives considering a typical nationwide U.S. backbone with projected IP traffic in approximately three years. Several sensitivity analysis results are also shown, to evaluate the effect of cost changes in some of the critical technological factors in these architectures, such as 10 Gb/s optics cost or IP router cost. The results show the value of transport layer networking architectures for multiterabit IP backbones, and how, when compared to service layer architectures, they provide additional desirable features such as wavelength reconfigurability and restoration scalability.

Geodetic techniques applied to the detection and monitoring of recent crustal movements

Geoditic space techniques became a very precise tool in detecting and monitoring recent crustal movements: in a well defined and exactly implemented frame of reference, mainly determined by very long baseline interferometry and absolute gravity a global system is established with centimeter accuracy within which repeated regional measurements of recent crustal movement can take place even over long intervals of time with high accuracy. Global Positioning system (GPS) meanwhile found its place, together with relative gravimetry, as an additional component which is directly related to the International Earth Rotation Service global system of reference. Repeated observations were carried out in various parts of the world which clearly demonstrate the high flexibility, impressive accuracy and extreme usefulness of GPS together with precise gravimetry. Detailed network design, accuracies and rates of repeated measurements, numerical results and analysis of data for short or large distances are considered. Moreover, the use of local geodetic techniques, based on tiltmeters, etc., and their combination with space methods is discussed. Specific problems associated with applications in Africa are pointed out.

Design of world loop networks and effectiveness evaluation of dynamic routing

AbstractIntercontinental optical submarine cables with larger capacities than conventional coaxial cables are now being developed. In accordance with international communication demand evolution and digitalization, worldwide optical submarine cable networks will be constructed. A loop network around the world in an east‐west direction, composed of optical submarine cables is considered to be an international backbone trunk network due to the advantages in simplicity, efficiency and reliability. Since the proposed design method aims at making a macroscopic network planning outline rather than making a detailed network design, the stochastic process of traffic is neglected and the traffic is treated as stationary flow. We present the strategies to evolve the world loop network and the increased traffic demand that reflects the actual international communication traffic trend. In addition to the conventional routing scheme in which mainly direct routes are used, a dynamic routing scheme in which routes composed of up to two tandem links are used is studied, and its effectiveness through network evolution is quantitatively evaluated.