Optimization Software Tools Research Articles

A Novel Mathematical Approach for Inductor-Current Expressions Definition in Multilevel Dual-Active-Bridge Converters

The study of multilevel dual-active-bridge (DAB) converters has garnered significant attention in recent years thanks to their advantages with respect to the conventional two-level (2L) DAB; namely, its greater performance and its capability to operate at higher voltage. The analysis of the converter high-frequency inductor current (iL) is crucial, for instance, to compute its root mean square (RMS) value, required to estimate the conduction losses in the converter. The mathematical expression of iL is piecewise and multiple variations, i.e., modes, exist depending on the modulation parameter values. This increases the complexity of converter performance analytical study. Thus, a more practical and generalizable expression of iL current is desirable. This paper proposes novel compact analytic expressions for the instantaneous and RMS inductor current in the 2L-NL DAB converter, leveraging binary functions to define the piecewise intervals and to identify the mode as a function of the modulation parameter values. The proposed method paves the way for more simple and computationally efficient DAB performance optimization software tools that allow exploring any given converter structures and modulation strategies.

The water energy food nexus: A multi-objective optimization tool

Many methods and tools are used to model and optimize various aspects of the water energy food nexus (WEFN). This work presents a novel software tool for the multi-objective optimization of the WEFN (MOO-WEFN). The model underlying the tool captures all three nexus sectors and the interlinkages between them. In addition, the model imposes constraints that mimic forces affecting the nexus, such as economics, environment, health, and nutrition. The software tool couples Excel with Python, which facilitates the tool's accessibility and ease of use due to its widespread usage and availability. A case study application demonstrates the tool's execution and provides examples of how changes can be made to the data to simulate different nexus developments. Five scenarios are applied to reflect such changes with results demonstrating the overall impact on resource production and consumption. Removing one of the less water-intensive food items results in a 20 % increase in water consumption. Limiting the availability of surface water results in a reallocation of water resources such that 80 % of water needs are satisfied from surface water and groundwater and 20 % from wastewater, compared to the baseline of 100 % surface water. Moreover, upon introduction of the conventional activated sludge treatment technology for wastewater (compared to the incumbent membrane bioreactor technology), energy consumption decreased by 10 %. These results show changes beyond the immediate sector of change and reflect the necessity for integrated modeling that captures the impact of one change on the nexus as a whole, in terms of resource consumption and allocation. Thus, the tool supports the capability of testing how new resources, technologies, and limitations will impact nexus interactions. Furthermore, the tool facilitates carrying out sensitivity and Pareto analyses for data generation and result evaluation.

Sustainable-Driven Renovation of Existing Residential Buildings in China: A Systematic Exploration Based on Review and Solution Approaches

Under the backdrop of China’s national strategy to achieve carbon neutrality by 2060, efforts are underway across governmental, corporate, societal, and individual sectors to actively explore energy-saving renovations in existing buildings. Given that residential buildings constitute a significant proportion of the total energy consumption throughout the lifecycle of buildings in China, sustainable renovation of residential structures can contribute significantly to implementing China’s carbon emission reduction policies. While there exists a plethora of technological means in the market aimed at improving the energy performance of residential buildings, there still needs to be a more systematic discussion on the framework for sustainable renovation of existing Chinese residential buildings, with knowledge dissemination still needing to be more cohesive. In this context, this paper provides a comprehensive review of the field, utilizing bibliometric methods. Through a systematic review of selected peer-reviewed literature from the Web of Science and Scopus databases, the study focuses on the sustainable renovation of existing Chinese residential buildings, categorizing the process into three main stages: sustainable renovation, building performance simulation and suitability assessment. The paper also reviews the research methods adopted by previous researchers in the renovation, simulation and assessment stages, considering various optimization algorithms, variables, objectives, and software tools. Subsequently, the paper synthesizes a research framework comprising these three stages combined for different research objectives, aiming to assist policymakers, designers, and researchers in gaining a comprehensive understanding of the implementation status of sustainable renovation in existing Chinese residential buildings, identifying barriers to implementation, and formulating more efficient renovation policies and strategies for the future.

A case study for optimization of power system load flow analysis using ETAP software

This research report explores the optimization of power system load current analysis by integrating Electrical Transient Analyzer Program (ETAP) software and Single Line Diagram (SLD) representation. Load current analysis is essential for the reliable and efficient operation of power grids, and the use of advanced software tools such as ETAP offers significant opportunities to improve analysis capabilities. The integration of SLD with ETAP enables more intuitive and comprehensive visualization of energy system elements and their connections, improving the modelling and analysis process. The article presents a case study that demonstrates the practical application of this integrated approach using a typical power system model to estimate load current characteristics under various operating conditions. The methodology involves building a powerful system model in ETAP and includes SLD representations to improve system visualization and analysis. The system simulation experiments evaluate the performance and accuracy of the integrated ETAPSLD approach, focusing on key parameters such as voltage profiles, current flows, enabling more efficient load current analysis and providing valuable information for power system engineers and operators. Overall, this study contributes to the field of energy system analysis by using advanced software tools for advanced modelling and optimization.

Planning Tools for Decentralized Heat Supply: Modeling the Effects of Volatile Renewable Energies

An increasing share of decentralized feed-in is necessary for the transition of district heating networks but it comes with various challenges. Software tools for modelling, simulation and optimization allow a theoretical examination of those challenges and possible solutions. Some of these have been used and further developed in the research project ZellFlex. One selected examination is the flexibility of supply temperatures by varying setpoint temperatures for a decentral solar thermal system (500 m²) integrated into an existing district heating network. The analysis of the supply temperature distribution in the network showed: A decrease of the solar thermal feed-in set point temperature by 5 K compared to the supply temperature of the central heat producer seemed acceptable in terms of security of supply, while a 10 K reduction comes with a high risk of undersupply. Furthermore, it was discovered that the points of time with the lowest supply temperatures at the consumers were just before and after they were provided with solar heat due to specific effects concerning temperature loss of the fluid.

A contribution to resource-efficient construction: Design flow and experimental investigation of structurally optimised concrete girders

In view of the current global climate challenges, the urgency for reduction of material consumption in the construction sector becomes clear. In this context, the present study concentrates on enhancing resource efficiency in concrete construction via the use of structural optimisation software tools as a guide for finding the geometry of optimised, mass-reduced concrete girders. Within a test series of eight specimens, varying parameters regarding the consulted optimisation strategy, the stirrup reinforcement type and concrete coverage were assessed. The experimental investigation was followed by a profound structural analysis, identifying peculiarities in the load-bearing behaviour and stiffness as well as two main failure modes characteristic of the optimised girder geometries. The comparison with full concrete girders illustrates the achieved reduction in concrete mass, the decrease of the Global Warming Potential of the production phase as well as the increase in the overall performance.

A Comprehensive Review on Techno-Economic Analysis and Optimal Sizing of Hybrid Renewable Energy Sources with Energy Storage Systems

Renewable energy solutions are appropriate for on-grid and off-grid applications, acting as a supporter for the utility network or rural locations without the need to develop or extend costly and difficult grid infrastructure. As a result, hybrid renewable energy sources have become a popular option for grid-connected or standalone systems. This paper examines hybrid renewable energy power production systems with a focus on energy sustainability, reliability due to irregularities, techno-economic feasibility, and being environmentally friendly. In attaining a reliable, clean, and cost-effective system, sizing optimal hybrid renewable energy sources (HRES) is a crucial challenge. The presenters went further to outline the best sizing approach that can be used in HRES, taking into consideration the key components, parameters, methods, and data. Moreover, the goal functions, constraints from design, system components, optimization software tools, and meta-heuristic algorithm methodologies were highlighted for the available studies in this timely synopsis of the state of the art. Additionally, current issues resulting from scaling HRES were also identified and discussed. The latest trends and advances in planning problems were thoroughly addressed. Finally, this paper provides suggestions for further research into the appropriate component sizing in HRES.

Custom software development of structural dimension optimization software for the buckling of stiffened plates

<abstract> <p>Existing structural optimization software tools only integrate the Euler buckling function of rods and plates and do not consider the buckling strength constraint of stiffened plates, thus failing to meet the optimization design requirements of thin-walled structures such as ship hulls. In this study, according to the buckling strength specifications for stiffened plates of ships, the custom software development of a structural optimization program with "buckling constraints of stiffened plates" was performed using the HyperMesh optimization design software. The finite-element grid of the stiffened plate was divided; the average stress, stress gradient and other parameters associated with the buckling of stiffened plates were determined; the DRESP3 card was set; the external OML function file was linked and the buckling strength of the stiffened plates was introduced into the dimensional optimization design model as a constraint. The proposed method was used to optimize the structure scantlings of a platform, achieving a reduction of 8.96% compared with the original scheme, while also meeting the requirements of structural strength, deformation and buckling strength. The results demonstrated that the dimensional optimization software with buckling constraints is operable and can aid in the rapid structural optimization design of stiffened plates.</p> </abstract>

Use of Universal Simulation Software Tools for Optimization of Signal Plans at Urban Intersections

Intersections in cities are important transport hubs, where traffic flows from all roads meet, connect, disconnect or intersect. This research is dedicated to the creation of simulation models of intersections and is based on real observations of two crossroads in a city. The principle is based on observing traffic flows using real traffic counting at peak times. The aim is to reduce traffic congestion by adjusting signal plans on the monitored section using computer simulation and modelling in ExtendSim8 software, which is a universal tool allowing the user to simulate any system or process by creating a logical representation in an easy-to-use format. According to our preliminary literature research, the ExtendSim software has never before been used before to create an intersection simulation to optimize the signal plan. There are several specialized software products for simulating traffic and intersections, but not everyone has access to these, or else they require lengthy user training. Therefore, it is very advantageous to use a universal simulation tool that is not used for traffic simulation at intersections in the city. The article points out that a universal simulation program such as ExtendSim can also be used in the design or assessment of signal plans at intersections.

Nonlinear MPC for collision-free and deadlock-free navigation of multiple nonholonomic mobile robots

In this paper, we present an online nonlinear Model Predictive Control (MPC) method for collision-free, deadlock-free navigation by multiple autonomous nonholonomic Wheeled Mobile Robots (WMRs). Our proposed method solves a nonlinear constrained optimization problem at each time step over a specified horizon to compute a sequence of optimal control inputs that drive the robots to target poses along collision-free trajectories, where the robots’ future states are predicted according to a unicycle kinematic model. To reduce the computational complexity of the optimization problem, we formulate it without stabilizing terminal constraints or terminal costs. We describe a computationally efficient approach to programming and solving the optimization problem, using open-source software tools for fast nonlinear optimization and applying the multiple-shooting method. We also provide rigorous proofs of the feasibility of the optimization problem and the stability of the proposed method. To validate the performance of our MPC method, we implement it in both 3D robot simulations and experiments with real nonholonomic WMRs for different multi-robot navigation scenarios with up to six robots. In all scenarios, the robots successfully navigate to their goal poses without colliding with one another or becoming trapped in a deadlock.

Structural Optimization through Biomimetic-Inspired Material-Specific Application of Plant-Based Natural Fiber-Reinforced Polymer Composites (NFRP) for Future Sustainable Lightweight Architecture.

Under normal conditions, the cross-sections of reinforced concrete in classic skeleton construction systems are often only partially loaded. This contributes to non-sustainable construction solutions due to an excess of material use. Novel cross-disciplinary workflows linking architects, engineers, material scientists and manufacturers could offer alternative means for more sustainable architectural applications with extra lightweight solutions. Through material-specific use of plant-based Natural Fiber-Reinforced Polymer Composites (NFRP), also named Biocomposites, a high-performance lightweight structure with topology optimized cross-sections has been here developed. The closed life cycle of NFRPs promotes sustainability in construction through energy recovery of the quickly generative biomass-based materials. The cooperative design resulted in a development that were verified through a 1:10 demonstrator, whose fibrous morphology was defined by biomimetically-inspired orthotropic tectonics, generated with by the fiber path optimization software tools, namely EdoStructure and EdoPath in combination with the appliance of the digital additive manufacturing technique: Tailored Fiber Placement (TFP).

Methodology and Software Tool for Energy Consumption Evaluation and Optimization in Multilayer Transport Optical Networks

In communication networks, the volume of traffic, the number of connected devices and users continues to grow. As a result, the energy consumption generated by the communication infrastructure has become an important parameter that needs to be carefully considered and optimized both when designing the network and when operating it in real-time. In this paper, the methodology of calculation of complex parameters of energy consumption for transport telecommunication networks is proposed. Unlike the known techniques, the proposed methodology takes into account heterogeneity and multilayer networks. It also takes into account the energy consumption parameter during the downtime of the network equipment in the process of processing the service data blocks, which is quite an important task for improving the accuracy of energy consumption at the stage of implementing the energy-saving network. We also developed simulation software to estimate and manage the energy consumption of the optical transport network using the LabVIEW environment. This software tool allows telecommunication network designers to evaluate energy consumption, which allows them to choose the optimal solution for the desired projects. The use of electro-and acousto-optical devices for optical transport networks is analyzed. We recommended using electro-optical devices for optical modulators and acousto-optical devices for optical switches. The gain from using this combination of optical devices and the parameter of rij electro-optical coefficient and M2 acousto-optical quality parameter found in the paper is about 36.1% relative to the complex criterion of energy consumption.

Assessment and improvement of modeling the atmospheric attenuation based on aerosol optical depth information with applicability to solar tower plants

Accurate modeling of atmospheric attenuation phenomena is a crucial aspect for the performance of solar tower plants. The development of suitable models requires of reliable measurements of the extinction coefficient near surface. Continuous monitoring of the extinction coefficient at ground is being recorded at Plataforma Solar de Almería (PSA) facility in south-east Spain since July 2017 offering a unique and long experimental database for model assessment. This work presents the assessment of Polo’s model with over two years of ground measurements. In addition, a new corrected and improved version of the model is presented here with a very good performance, maintaining the versatility of the model. Hourly estimations of the atmospheric attenuation at PSA with the new version of the model resulted in a 6.1% of RMSE and very good agreements in both inter- and intra-annual variability is found. The new model proposed here is easy to be used in both ray-tracing, optimization software and performance tools commonly and widely used for modeling solar tower plants behavior and production. This new model offers a better and novel approach that can be used at any site where AOD information is available.

Performance Analysis of a Stirling Engine Hybrid Power System

The Bolivian government’s concerns that are related to reducing the consumption of diesel fuel, which is imported, subsidized, and provided to isolated electric plants in rural communities, have led to the implementation of hybrid power systems. Therefore, this article presents the performance analysis in terms of energy efficiency, economic feasibility, and environmental sustainability of a photovoltaic (PV)/Stirling battery system. The analysis includes the dynamic start-up and cooling phases of the system, and then compares its performance with a hybrid photovoltaic (PV)/diesel/battery system, whose configuration is usually more common. Both systems were initially optimized in size using the well-known energy optimization software tool, HOMER. An estimated demand for a hypothetical case study of electrification for a rural village of 102 households, called “Tacuaral de Mattos”, was also considered. However, since the characteristics of the proposed systems required a detailed analysis of its dynamics, a dynamic model that complemented the HOMER analysis was developed using MATLAB Simulink TM 8.9. The results showed that the PV/Stirling battery system represented a higher performance option to implement in the electrification project, due to its good environmental sustainability (69% savings in CO2 emissions), economic criterion (11% savings in annualized total cost), and energy efficiency (5% savings in fuel energy conversion).

A Matheuristic for Joint Optimal Power and Scheduling Assignment in DVB-T2 Networks

Because of the introduction and spread of the second generation of the Digital Video Broadcasting—Terrestrial standard (DVB-T2), already active television broadcasters and new broadcasters that have entered in the market will be required to (re)design their networks. This is generating a new interest for effective and efficient DVB optimization software tools. In this work, we propose a strengthened binary linear programming model for representing the optimal DVB design problem, including power and scheduling configuration, and propose a new matheuristic for its solution. The matheuristic combines a genetic algorithm, adopted to efficiently explore the solution space of power emissions of DVB stations, with relaxation-guided variable fixing and exact large neighborhood searches formulated as integer linear programming (ILP) problems solved exactly. Computational tests on realistic instances show that the new matheuristic performs much better than a state-of-the-art optimization solver, identifying solutions associated with much higher user coverage.

A new tool for automatic calibration of the Storm Water Management Model (SWMM)

The USEPA (United States Environmental Protection Agency) Storm Water Management Model (SWMM) is one of the most widely used numerical models to simulate urban runoff and drainage. A typical SWMM project has hundreds or thousands of sub-catchments and more than 20 parameters associated with six different physical processes for each sub-catchment. Consequently, model calibration is a challenging task. In this study, SWMM was integrated with the Optimization Software Tool for Research Involving Computational Heuristics (OSTRICH) to perform single- and multi-objective automatic calibration. The newly developed OSTRICH-SWMM is an open-source tool with dozens of parallelized optimization algorithms. A catchment in Buffalo, NY was selected as a case study and was calibrated according to two competing criteria: (1) minimizing errors in simulated peak flow, and (2) minimizing errors in total flow volume. The Pareto front for the case study was obtained using a multi-objective calibration algorithm and this allowed for evaluating tradeoffs between the peak flow and total volume criteria. The results demonstrate that OSTRICH-SWMM is a promising tool for automatic calibration of SWMM models.

SiRNA-Finder (si-Fi) Software for RNAi-Target Design and Off-Target Prediction.

RNA interference (RNAi) is a technique used for transgene-mediated gene silencing based on the mechanism of posttranscriptional gene silencing (PTGS). PTGS is an ubiquitous basic biological phenomenon involved in the regulation of transcript abundance and plants’ immune response to viruses. PTGS also mediates genomic stability by silencing of retroelements. RNAi has become an important research tool for studying gene function by strong and selective suppression of target genes. Here, we present si-Fi, a software tool for design optimization of RNAi constructs necessary for specific target gene knock-down. It offers efficiency prediction of RNAi sequences and off-target search, required for the practical application of RNAi. si-Fi is an open-source (CC BY-SA license) desktop software that works in Microsoft Windows environment and can use custom sequence databases in standard FASTA format.

Засіб налаштування програм на платформі .NET за допомогою переписувальних правил

Software tool for computation optimization that allows to optimize semiautomatically to increase execution speed was developed. Plugin for TermWare system, which implements the concept of rewriting rules, was developed. The plugin represents an analyzer for C# using Roslyn platform and generates terms for TermWare system from source code. The work of software tool was illustrated on «Conway's Game of Life» - famous academic example. A comparison of the results of processing the implementation of the algorithm using the TermWare system and the Eazfuscator.NET library was given. The results were obtained by experiments on various data sizes. Speed of the program before and after modifications, the number of modifications required in the source code to work with the system was measured. The developed system and Eazfuscator.NET framework were tested on personal computer.

Development of an intelligent system for integrated management of hydroelectric cascade modes

The paper deals with an isolated electric power system (EPS) based on hydroelectric power plants. The analysis of the existing methods and approaches for investigation of modes of EPS which comprise hydroelectric power plants is presented. A mathematical model of a hydroelectric station cascade has been developed, which allows taking into account the hydraulic connection during calculation of electrical modes. A software tool for optimization the operating modes of hydroelectric power plants as part of the power system was developed. It uses redistribution the load between hydraulic units both inside the station and between hydroelectric complexes of cascade hydroelectric stations. The task of modeling power consumption and load graphs of EPS with specific properties, based on the application of artificial intelligence methods, is considered.

Optimized design of robust resonator with distributed time-delay

An extension of the well-known delayed resonator concept is proposed with the objective to enhance its robustness in vibration suppression under guaranteeing stability of the overall set up. The novel resonator feedback is based on an acceleration measurements passing through a delay of polynomial distribution. The feedback design is formulated as an optimization problem over the parameter set formed by the polynomial coefficients and the gain of the delay free part. The first objective is to minimize the sensitivity of the resonator performance with respect to variations of the excitation frequency, i.e. to widen its frequency stop-band centered at the nominal excitation frequency. The second, equally significant objective is to guarantee that this does not lead to instability of the overall mechanical system coupled with the absorber and to ensure sufficient stability margin. The arising non-convex and non-smooth optimization problem is widely discussed and a penalty method is developed, where the unconstrained problem in every iteration step is solved using available software tools for optimization and spectral design of time delay systems. The proposed design technique is validated by simulations for two case study examples.