Design Of Distributed Systems Research Articles

BlockEdge: Building Bridges to Safe and Efficient Distributed Systems

Abstract: In the ever-evolving landscape of distributed systems, ensuring safety, efficiency, and scalability remains a paramount challenge. BlockEdge emerges as a pioneering framework designed to address these critical issues by leveraging the principles of blockchain technology and advanced consensus mechanisms. This abstract outlines the key features, innovations, and potential impacts of BlockEdge on the realm of distributed computing. BlockEdge integrates blockchain's immutable ledger properties with a novel consensus algorithm tailored for distributed systems. Unlike traditional blockchain applications that prioritize decentralization for financial transactions, BlockEdge focuses on enhancing the performance and reliability of distributed applications. The framework employs a hybrid consensus model that combines Byzantine Fault Tolerance (BFT) with Proof-of-Stake (PoS), optimizing both security and energy efficiency. A standout feature of BlockEdge is its modular architecture, which allows seamless interoperability between different types of distributed networks. This modularity facilitates the integration of various consensus protocols, catering to the specific needs of diverse applications, from IoT networks to large-scale data processing systems. By enabling secure and efficient cross-chain communication, BlockEdge effectively mitigates the silo effect prevalent in current distributed system designs.

A Branch-and-Price Algorithm for an Integrated Online and Offline Retailing Distribution System with Product Return

This study identifies critical inefficiencies within a dual-channel operation model employed by a fast fashion company, particularly the independent operation of three logistics distribution systems. These systems result in high operational costs and low resource utilization, primarily due to redundant vehicle dispatches to meet the distinct demands of retail store replenishment, online customer orders, and customer return demands, as well as random and scattered return requests leading to vehicle underutilization. To address these challenges, we propose a novel integrated logistics distribution system design and management method tailored for dual-channel sales and distribution businesses. The approach consolidates the three distribution systems into one cohesive framework, thus streamlining the delivery process and reducing vehicle trips by combining retail and customer visits. An optimization algorithm is introduced to factor in inventory and distribution distance, aiming to achieve global optimization in pairing retail store inventory with online customer orders and unifying the distribution of replenishment products, online products, and returned products. The paper contributes to the field by introducing a new variation of the Vehicle Routing Problem (VRP) that arises from an integrated distribution system, combining common VRP issues with more complex challenges. A custom Branch-and-Price (B&P) algorithm is developed to efficiently find optimal routes. Furthermore, we demonstrate the benefits of the integrated system over traditional, segregated systems through real-world data analysis and assess various factors including return rates and inventory conditions. The study also enhances the model by allowing inventory transfers between retail stores, improving inventory distribution balance, and offering solutions for scenarios with critically low inventory levels. Our findings highlight a significant reduction in total operating cost savings of up to 49.9% and vehicle usage when using the integrated distribution system compared to independent two-stage and three-stage systems. The integrated approach enables the utilization of vacant vehicle space and the dynamic selection and combination of tasks, preventing unnecessary mileage and space wastage. Notably, the integration of inventory sharing among retail stores has proven to be a key factor in generating feasible solutions under tight inventory conditions and reducing operational costs and vehicle numbers, with the benefits amplified in large-scale problem instances.

Water distribution system modelling of GIS-remote sensing and EPANET for the integrated efficient design

Abstract Urban settlement depends on water distribution networks for clean and safe drinking water. This research incorporates geographic information systems (GIS), remote sensing (RS), and hydraulic modelling software EPANET to analyse and construct water distribution systems in Bota town, India. Satellite images and hydrological data have been utilized for the management of the Bota town's water supply network, sources to cater the demand for urban centres. EPANET simulates hydraulic behaviour in the water distribution system under different operating situations. EPANET simulation shows network leaks, low pressure, and substantial head loss. These findings have advised for water distribution system improvements by analysing network shortcomings. Booster pumps, new pipelines, and repairing of existing leakages are examples of such improvements. GIS, RS, and EPANET provided a comprehensive water distribution system study and more accurate and efficient improvement identification. This study emphasizes the necessity of new technologies in water distribution system analysis and design. The study solves Bota town's water distribution system problems of low pressure, high head loss, and leaks utilizing GIS, RS, and EPANET. The findings of this research can help in enhancing the water delivery systems in other towns with comparable issues.

Design of a high-precision clock distribution and synchronization system

In large-scale nuclear and particle physics experiments, there is a high demand for high precision clock distribution and synchronization. In this paper, the design and testing of a high precision clock distribution and synchronization system for the CSR External Target Experiment (CEE) is presented. To achieve high synchronization precision, a dedicated high-quality clock distribution network is designed, while the timestamp synchronization is achieved over the existing trigger link in CEE with a customized protocol in order to simplify the system structure. Automatic metastability elimination and real-time monitoring of both the timestamps on the front end nodes and the clock electronics status are also implemented. The test results indicate that the period jitter of the clock network is better than 4 ps rms, and all the expected functionalities have been achieved successfully.

Optimization of Subsidized Fertilizer Distribution System Design in East Java Due to Uncertainty Factors

Objective: The purpose of this study is to optimize the optimal location and number of distribution warehouses in the face of a significant decrease in the allocation of subsidized Urea and NPK fertilizers. This research is conducted on subsidized fertilizers with multi-product characteristics (Urea and NPK fertilizers), multi-period (2021-2022), and uncertainty (government policy on allocation). The objectives of this study are produce a distribution network design model and optimize the number and location of warehouses needed to minimize total logistics costs.
 
 Methods: This research uses a quantitative approach in solving the problems faced by companies. To obtain the lowest logistics cost, optimization calculations are performed via model development. The model employed is mixed integer linear programming, which employs a combination of multi-source capacitated models, multi-product models, and multi-stage models. Furthermore, by examining storage consumption, the optimization calculation may be utilized to estimate the existing amount of storage facilities. The anticipated goal is to reduce logistical costs and enhance warehouse usage for storing subsidized fertilizer.
 
 Results: The results of this study from 43 warehouses to 33 warehouses located in East Java Province with operational savings costs that can be obtained by PT Petrokimia Gresik amounting to IDR 1,863,794,700.

Numerical simulation of convective heat transfer in the discharging process of external ice-melting ice storage systems

The external ice-melting ice storage system was widely used because of its advantages of reducing peak power consumption, reducing energy consumption and emissions, and fast ice melting speed. However, designing the external ice-melting ice storage system proved to be a challenge, and the structure and flow of the water distribution system needed to be fully considered. In particular, the problem of unstable outlet water temperature limited the practical application of the external melting ice storage system. Aiming at the problem of unstable outlet water temperature, a three-dimensional CFD phase change model was constructed in this paper. By comparing with the experimental data, the impact of varying water flow rates on the thermal and cooling properties of the was investigated. The results indicated that when the water flow rate was 226 ml/min for the system with an ice thickness of 74 mm, the outlet temperature of the ice storage tank was consistently below 5°C, the Nusselt number of ice and water remained constant, and the convective heat transfer effect was improved. The numerical simulation results provided guidance for the design and practical application of the water distribution system of the external melting ice storage system.

A Review of Demand-Side Resources in Active Distribution Systems: Communication Protocols, Smart Metering, Control, Automation, and Optimization

Power systems have been going through a barrage of transformations due to the recent developments in the field, such as deregulation and restructuring of the electric power supply chain, the proliferation of distributed generation (DG), and advancements in information and communications technologies. These have significantly impacted the approach to the planning, design, and operation of active distribution networks or systems. Due to this constant change, the system has become more complex to plan, maintain, and control. In this paper, the benefits and challenges of active distribution systems relative to traditional passive and active distribution systems are evaluated and investigated while the management and operational characteristics of demand-side resources in active distribution systems (ADS) are studied. In a typical ADS, there exist several vulnerabilities and threats that eventually pose a challenge in the control and automation of substations. These vulnerabilities and threats are reviewed, and potential mitigation measures are suggested. Also in this paper, the communication technologies and their implementation in terms of control and automation capabilities in active distribution networks are also studied. From this work, it is concluded that communication technologies play an integral role in the realization of more active distribution networks and that the Internet of Energy (IoE) is a major player in ADS in the reduction of faults due to human error, fast responses, and improving the stability of power supply. Cyber threats are also and will still be a continuous challenge in smart metering technologies and in substation automation systems (SAS), which will require frequent evaluation and mitigation measures so as not to prevent the power supply system from collapsing.

Numerical and experimental investigation of a multi-channel heat sink distribution header designed by topology optimization

The fluid distribution had a significant effect on the performance of the I-shaped multichannel heat sink. Previous researchers have improved fluid distribution by arranging baffles; however, this resulted in an increased pressure drop. In this study, a multichannel radiator distribution header was designed using a topological optimization method, and experimental and numerical studies were conducted. Both a numerical model and physical prototype were created and subsequently evaluated to assess the performance of the resultant distribution header. The effects of the distribution and conventional headers on the performance of a multichannel heat sink were compared. The results demonstrated that the distribution header designed using the topology optimization method can significantly improve multichannel performance. The optimized header design exhibited improved flow distribution rationality, enhanced heat dissipation, and reduced pressure drop compared to the two conventional designs. The volume flow rate was reduced by 58.66% and 59.29%, the heat transfer coefficient was increased by 29.39% and 21.42%, and the pressure drop was reduced by 9.38% and 16.98%. A peach-shaped baffle plays an important role in fluid distribution. These findings highlight the effectiveness and potential of topology optimization in the design of complex fluid distribution systems for heat exchanger.

Complementarity reformulations for the optimal design of distributed energy systems with multiphase optimal power flow

The optimal design of grid-connected distributed energy systems (DES) has been previously investigated, but most studies exclude nonlinear multiphase optimal power flow (MOPF) constraints which capture imbalances in alternating current (AC) distribution networks. Previous DES design studies considering AC power flow assume balanced loads and networks, which is an assumption that does not hold for distribution networks that are often inherently unbalanced. This is the first study to present an optimisation framework for designing grid-connected DES while simultaneously considering multiphase optimal power flow (MOPF) constraints to accurately represent unbalanced low-voltage distribution. This study proposes a new algorithm for obtaining DES designs subject to nonlinear multiphase power flow constraints with regularised complementarity reformulations for operational constraints containing binary variables. DES design models with either MOPF or OPF are tested using an unbalanced distribution network, where rooftop solar, gas boilers, and battery storage are considered as distributed resources. Despite the increased complexity, DES design with MOPF obtains the best solution, with 81% greater solar capacity and 6% lower total annualised cost when compared to DES with OPF. Designs from a commonly-used linear DES design framework based on direct current (DC) approximations produce the highest costs (8% more than initially predicted) when tested with MOPF. The proposed algorithm with complementarity reformulations achieves a 19% improvement in the objective value over a previous two-stage decomposition for DES with OPF, where the entire binary topology in the nonlinear model is fixed. The study therefore enables the acquisition of DES designs that can work symbiotically within unbalanced distribution networks.

Cryogenic distribution system design for cryomodules and cavities test in HIAF project

ABSTRACT High-intensity heavy-ion accelerator facility (HIAF) is an accelerator-driven high-current heavy ion facility, currently under construction in Guangdong, China. The proton linear accelerator of HIAF linac has 96 superconducting cavities and 17 cryomodules cooled by 2 K saturated superfluid helium. Cryogenic tests should be carried out in a test cryogenic system prior to the online operation of each cavity and cryomodule. The cryogenic distribution system (CDS) is the main part of the test cryogenic system, which is used for transporting cryogenic fluid between helium refrigerator and test terminals. A specific CDS is developed due to the long cryogenic test time. Each test terminal can be independently cooled and heated up, saving quite a bit of time without impacting the others. This article provides comprehensive explanations for the process design, process analysis, and special structure design which enhance the system’s maintainability. Furthermore, particular technical designs, such as measuring system, helium guard, and elimination of thermoacoustic oscillations, are described in detail.

An optimization model for the layout of a branching water distribution system

This paper presents an optimization model for the layout of a branching water distribution system. The goal is to minimize construction costs while meeting the system's demands. The study utilizes the general algebraic modeling system (GAMS) to optimize a non-looping water distribution system. The methodology involves determining the existence and diameter of connections between demand nodes. The optimization problem is formulated as a mixed-integer non-linear programming (MINLP) problem. A simplified layout is used to illustrate the constraints and validate the model. The explicit model implemented in GAMS yields optimal solutions and demonstrates the effectiveness of the approach. The results highlight the decisions on connection existence, flow, and pipe diameter, contributing to cost minimization. The findings from this study provide insights for optimizing the design of branching water distribution systems and reducing construction costs.

Coordinated design of multi-stakeholder community energy systems and shared energy storage under uncertain supply and demand: A game theoretical approach

Shared energy storage plays an important role in achieving sustainable development of renewable-based community energy systems. In practice, the independent or disordered planning of community energy systems and shared storage systems can lead to suboptimal design without considering the complex interactions between neighboring energy systems. Therefore, a coordinated design approach for community energy systems and shared energy storage is proposed, and a pricing mechanism for storage sharing based on bounded rationality theory is developed. A Stackelberg game is introduced to enable consideration of storage sharing among energy systems at the design phase. The uncertainties of solar irradiation, wind speed, and electrical demand on both the supply and demand sides are also considered. Then, an uncertainty model is formed to optimize the system configurations, operation strategies, and storage sharing strategies of each stakeholder, simultaneously. Furthermore, the influence of the profit margin, storage investment cost, and carbon tax on the storage rental price and system design strategies are discussed. Illustrative examples highlight the feasibility and applicability of the shared storage pricing mechanism and coordinated design approach. This paper provides references for the government with respect to the problem of coordinated design for multi-stakeholder distributed energy systems and storages in a market-oriented environment.

Optimal Probabilistic Allocation of Photovoltaic Distributed Generation: Proposing a Scenario-Based Stochastic Programming Model

The recent developments in the design, planning, and operation of distribution systems indicate the need for a modern integrated infrastructure in which participants are managed through the perceptions of a utility company in an economic network (e.g., energy loss reduction, restoration, etc.). The penetration of distributed generation units in power systems are growing due to their significant influence on the key attributes of power systems. As a result, the placement, type, and size of distributed generations have an essential role in reducing power loss and lowering costs. Power loss minimization, investment and cost reduction, and voltage profile improvement combine to form a conceivable goal function for distributed generation allocation in a constrained optimization problem, and they require a complex procedure to control them in the most appropriate way while satisfying network constraints. Such a complex decision-making procedure can be solved by adjusting the dynamic optimal power flow problem to the associated network. The purpose of the present work is to handle the distributed generation allocation problem for photovoltaic units, attempting to reduce energy and investment costs while accounting for generation unpredictability as well as load fluctuation. The problem is analyzed under various scenarios of solar radiation through a stochastic programming technique because of the intense uncertainty of solar energy resources. The formulation of photovoltaic distributed generation allocation is represented as a mixed-integer second-order conic programming problem. The IEEE 33-bus and real-world 136-bus distribution systems are tested. The findings illustrate the efficacy of the proposed mathematical model and the role of appropriate distributed generation allocation.

Optimal Selection of Conductors in Distribution System Designs Using Multi-Criteria Decision

The growth in the demand for electrical energy, which is driven by the constant growth of the metropolises and the expansion of the productive capacities of the industrial sector, entails the inevitable development of the electrical system to satisfy all the required demands in a convenient, efficient, and reliable manner. In this scenario, power distribution companies will continue to need to expand their electrical systems in the short and medium term to obtain the lowest investment and operating prices for the period considered in the analysis horizon. The expansion of the system can be projected statically or dynamically, which depends on the criteria that each distributor, in turn, applies in their expansion projects. Multi-criteria decision making can provide deeper analysis perspectives considering infinite possibilities for optimal network sizing and the technical, operational, quality of service, and even system reliability factors. This research proposes a multi-criteria decision technique based on the CRITIC method to determine the optimal design of an electrical distribution system. For this purpose, several design scenarios are defined with different types of electrical conductors, and the power flows are calculated in each. From these simulations, the results obtained in voltage profiles, namely active and reactive power losses, current levels, and the costs associated with the conductors used, are recorded. With the multi-criteria technique, the winning alternative is the design scenario containing the best joint solutions for the analysis variables. The proposed methodology is validated in an IEEE 34-bar test system. The Matpower tool, available through Matlab, generates power flows for each proposed design case. The results obtained in the analysis variables are generated and stored in a decision matrix of 210 alternatives. The proposed method represents a novel and powerful alternative for design proposals of distribution systems considering quality, efficiency, and cost criteria.

Verification of a Modeling Toolkit for the Design of Building Electrical Distribution Systems

DC electrical distribution systems offer many potential advantages over their AC counterparts. They can facilitate easier integration with distributed energy resources, improve system energy efficiency by eliminating AC/DC converters at end-use devices (e.g., laptop chargers), and reduce installation material, time, and cost. However, DC electrical distribution systems present additional design considerations, largely resulting from potentially greater magnitude and variation in cable losses. Modeling and simulation are rarely used to design such systems. However, the greater dependency of DC system energy efficiency on design choices such as distribution voltages, architecture, and integration of PV and BESS suggests that modeling and simulation may be required. Such system performance analysis is currently not a standard practice, in part due to limited availability and validation of capable software tools. This paper characterizes the accuracy of a Modelica-based Building Electrical Efficiency Analysis Model (BEEAM) toolkit, as a precursor for validating its use to perform system performance analysis and inform design decisions. The study builds upon previous verification research by characterizing complete systems comprised of commercially available equipment, and providing a more detailed analysis of simulation results. Five lighting systems with varying electrical distribution architectures were designed using market-available equipment, installed in a laboratory environment, modeled using BEEAM, and simulated using three Modelica integrated development environments (IDEs). Simulated and measured results were compared to characterize toolkit accuracy. Initial results revealed that simulated performance was mostly within ±5% of measured system-level and device-level performance. While simulation results were not found to be dependent on the IDE, some Modelica compiler interoperability issues were identified. Although the BEEAM toolkit showed promise for the targeted use case, further work is needed to determine whether the demonstrated 5% accuracy is sufficient for making real-world design decisions, and for BEEAM to advance from an interesting research tool to one that can impact real-world building projects.

Testability design of power distribution system considering noise immunity characteristics

MOSFET-based power electronics systems have high-reliability requirements, and a high-accuracy fault diagnosis method is necessary. However, imperfect conditions such as severe signal noise and poor consistency exist in actual products. Conventional fault diagnosis methods are difficult to identify faults accurately. This paper describes a simulation-based testability design method for batch products considering noise immunity. First, the components' soft and hard fault models are determined with failure mode and effect analysis (FMEA), and the circuit simulation model is constructed. Then, the fault injection simulation is performed to structure the dependency matrix. The test points scheme is selected and optimized by extracting noise immunity characteristics of different types of signals. Finally, a power distribution system is taken as a case study for the testability design method, and the effectiveness of the test points is evaluated through simulation and experiment verification.

Accuracy of CFD Simulations on Indoor Air Ventilation: Application of Grid Convergence Index on Underfloor Air Distribution (UFAD) System Design

Underfloor air distribution system (UFAD) mesh flow velocity was simulated using Computational Fluid Dynamics (CFD). Three mesh sizes were used to explore the domain's core x-y plane velocity contour and profiles. Compared to medium and fine, the coarse mesh underestimated the velocity significantly. A slight discrepancy occurred where the shear flow was dominant. The symmetrical flow velocity for both sides of the room length was shown in the xy-plane at the centre of the inlet. The mean error for coarse and medium mesh was larger than for the medium and fine mesh. It shows that the difference between the medium mesh and the fine was accepted. The computational time for medium mesh was acceptable for simulation, and it will not vary substantially even if the grid is refined further. The normalised mean square error (NMSE), the factor of two observations (FAC2), the factor of 1.3 observations (FAC1.3), and the fractional bias (FB) are used to measure the performance of the models and the value of the outcomes was exceptional. As a result, the accuracy of the finding can be improved by conducting additional research with manikins and in a fully occupied room under real-world conditions. In addition, this study could analyse and anticipate the optimal scenario regarding ventilation performance, etc.

Multi-scenario design of ammonia-based energy storage systems for use as non-wires alternatives

Energy storage can be used by power distribution system operators as a non-wires alternative to defer infrastructure upgrades and improve feeder reliability. One emerging energy storage technology is energy storage via the synthesis and subsequent consumption of chemicals in internal combustion engines or fuel cells (i.e., ”chemical energy storage”). Some chemicals, such as hydrogen and ammonia, can be synthesized from renewable, carbon-free feedstocks using excess renewable generation. In this work, we develop an optimization model for investing in and using mobile ammonia-powered generators, ammonia storage equipment, and mobile batteries in tandem to provide non-wires alternatives to distribution networks efficiently. Specifically, we develop a mixed-integer quadratically constrained program to optimize the design and operation of distribution systems with ammonia and battery energy storage devices under multiple operational scenarios. This formulation is applied in a case study on a 15-bus test system. Ultimately, we find that ammonia-powered generators enable flexible operation and are best suited for long-term, high-total-energy use cases, whereas batteries are best suited for short-term use cases. Additionally, we find that a combination of chemical and electrochemical energy storage is more cost effective at responding to a variety of operational conditions than either form of energy storage alone.

Corrections to “Optimization of MV Distribution System Designs”

Corrections to “Optimization of MV Distribution System Designs”

Energy intensity-based metric for optimal design of water distribution systems

Water distribution systems (WDSs) are some of the most energy-intensive urban infrastructures and thus require efficient energy management. As an essential public infrastructure, a WDS plays an integral role in meeting the water needs of its users at service pressure. Hence, the service level should also be considered when reducing the energy consumption of the WDS. Therefore, to evaluate both energy management and service level, this study proposes efficient returned pressure (ERP) as a metric to optimize the WDS in both aspects by comparing the service pressure to the required energy intensity. During its operating cycle, the ERP considers the pressure and required energy intensity of the demand junctions resulting from the connection of various WDS elements. Using ERP as an optimization objective against the cost for three cases of different active network element configurations, it was discovered that ERP successfully identified solutions that could maximize service pressure while maintaining a minimum required energy intensity. Using ERP provided more effective solutions in terms of cost, greenhouse gas emissions, and network pressure uniformity compared to a conventional index such as the modified resilience index. Overall, the ERP proves to be a feasible optimization parameter when pressure and energy usage is of concern.