Operational Problems Research Articles

Impact of different regulatory approaches in renewable energy communities: A quantitative comparison of european implementations

Recently, the uptake of renewable energy has surged in distribution networks, particularly due to the cost-effectiveness and modular nature of photovoltaic systems. This has paved the way to a new era of user engagement, embodied by individual and collective self-consumption, and promoted by the EU Directive 2018/2001, which advocates for the establishment of Renewable Energy Communities. However, the transposition of this directive varies across Member States, resulting in specific rules for each country. In this work, the impact that different energy sharing models have on the same community is quantitatively assessed. The policy analysis focuses on the regulation of two countries, Italy and Portugal, chosen for the specular ways in which their models operate, respectively virtually and physically. The analysis is supported by a suite of tools which includes two optimization problems for community's operations, one for each analysed regulation, and a set of consumer protection mechanisms, to ensure no member is losing money while in community. Results demonstrate that the sharing model impacts community's optimal operations, optimal battery size and configuration, and members' benefit. As these models are sensitive to different variables, personalized interventions at national level are required.

Multi-objective optimization and multi-attribute decision-making support for optimal operation of multi stakeholder integrated energy systems

To efficiently tackle the optimal operation problem of multi-stakeholder integrated energy systems (IESs), this paper develops a multi-objective optimization and multi-attribute decision-making support method. Mathematically, The optimal operation of IESs interconnected with distributed district heating and cooling units (DHCs) via the power grid and gas network, can be formulated as a multi-objective optimization problem considering both economic, reliability and environment-friendly objectives with numerous constraints of each energy stakeholder. Firstly, a multi-objective group search optimizer with probabilistic operator and chaotic local search (MPGSO) is proposed to balance global and local optimality during the random search iteration. The MPGSO utilizes a crowding probabilistic operator to select producers to explore areas with higher potential but less crowding and reduce the number of fitness function calculations. Moreover, a new parameter selection strategy based on chaotic sequences with limited computational complexity is adopted to escape the local optimal solutions. Consequently, a set of superior Pareto-optimal fronts could be obtained by the MPGSO. Subsequently, a multi-attribute decision-making support method based on the interval evidential reasoning (IER) approach is used to determine a final optimal solution from the Pareto-optimal solutions, taking multiple attributes of each stakeholder into consideration. To verify the effectiveness of the MPGSO, the DTLZ suite of benchmark problems are tested compared with the original GSOMP, NSGA-II and SPEA2. Additionally, simulation studies are conducted on a modified IEEE 30-bus system connected with distributed DHCs and a 15-node gas network to verify the proposed approch. The quality of the obtained Pareto-optimal solutions is assessed using a set of criteria, including hypervolume (HV), generational distance (GD), and Spacing index, among others. Simulation results show that the number of Pareto-optimal solutions (NPS) of MPGSO are higher by about 32.6 %-62.1%, computation time (CT) are lower by about 2.94 %-46.1 % compared with other algorithms. Besides, to further evaluate the performance of the proposed approach in addressing larger-scale issues, the study employs the modified IEEE 118-bus system of greater magnitude. The proposed MPGSO algorithm effectively handles multi-objective and non-convex optimization problems with Pareto sets in terms of better convergence and distributivity.

Multiple-point ignition as a driver of flame acceleration at the early stage of burning in channels

In the present study, flame acceleration driven by an array of multiple ignition kernels, equally spaced in the axial direction of a channel closed at one end, is studied numerically. In order to demonstrate the effects of the proposed ignition configuration on the flow dynamics, free-slip wall boundary condition is adopted. It is demonstrated that the burning of multiple flame kernels generates a powerful upstream flow, propelling the flame kernels, with the leading kernel’s tip undergoing a strong exponential acceleration. In a channel with smooth walls, such a powerful acceleration process is limited in time. The present study is mainly focused on the dynamics of the flame during the exponential stage of acceleration. The dependence of the acceleration rate, total acceleration time, and the maximum flame velocity on the initial distance between the kernels, the number of ignition kernels, and the thermal gas expansion coefficient, is quantified. Remarkably, the initial distance between the kernels has a weak influence on the above mentioned characteristics of flame dynamics as long as it is sufficiently large. It is observed that the acceleration rate increases with the kernel number. Notably, a significantly large maximum flame tip velocity can be achieved using the multi-kernel configuration as compared to the single-point ignition scenario. The acceleration rate demonstrates a nearly linear dependence on the thermal expansion coefficient, thus, the increase in thermal expansion results in a considerably stronger flame acceleration process.Novelty and Significance StatementFor the first time, the flame acceleration process upon simultaneous ignition of a multi-point array of hot kernels equally spaced at the centerline of a channel was systematically studied. The work emphasizes the potential for achieving an extremely high flame speed within a very short time as compared to the single-ignition method. The acceleration rate, total acceleration time, and maximum achievable flame velocity were quantified. In a multi-point ignition scenario, we demonstrate that the burning of the fresh mixture between the kernels increases an overall cumulative gas expansion, propelling the leading tip. This result suggests a method for creating a powerful flame acceleration, which is an essential step in deflagration-to-detonation transition. Notably, the powerful acceleration is achieved in channels with smooth walls, which is important for DDT applications, in which using obstructed channels may be associated with a range of operational problems. The simplicity of the setup is also emphasized.

Application of selected indicators to assess contamination of municipal landfill leachate and its impact on groundwater

Leachate formation is one of the most important factors taken into account during the operation and long-term management of municipal waste landfills. Systematic assessment of groundwater and leachate contamination may be useful in selecting the appropriate method of leachate management or treatment processes. The use of indicators to quantify the contamination potential of leachate and groundwater in the vicinity of MSW could help landfill managers assess their quality. Therefore, the aim of the study was to assess the representativeness of selected indicator methods for analyzing the temporal variability of leachate and groundwater properties in the vicinity of two municipal waste landfills in a Central European country (Poland). The leachate pollution index (LPI), sub-LPI and adjusted leachate pollution index (r-LPI) were used to assess the quality of leachate water, while the landfill water pollution index (LWPI) was used to assess the variability of groundwater quality. The results confirmed that LWPI is an effective method for assessing the quality of groundwater in the vicinity of municipal waste landfills. The obtained results confirm the negative impact of landfills, despite the insulation used. LWPI showed poor quality of groundwater and visible impact of the landfill (landfill W, average LWPI - 2.34) and moderately polluted waters and minor impact of the landfill (landfill S, average LWPI - 1.37). In most cases, it was observed that two parameters, EC and TOC, are the main factors contributing to the deterioration of groundwater quality. The sub-LPI analysis showed that leachates from both landfills have a very low content of heavy metals, so they should not have a negative impact on the biological treatment process. The obtained r-LPI values were in all cases higher than the calculated LPI values. For landfill S, the average r-LPI was 26.3 (Z-1) and 25.7 (Z-2). However, the average LPI was 13.5 (Z-1) and 13.2 (Z-2). For landfill W, the average r-LPI was 14.6 and the average LPI was 11.4. Analysis conducted on multi-year leachate and groundwater data using specific indicators can help managers better understand the impact of MSW on surrounding areas and help avoid potential operational problems in the future.

Operational Challenges of Small Scale Enterprises in Namakkal District

The research work examined the operational problems those hinder the efficacy and productivity of the SSEs in the jurisdiction of Namakkal District. This scientific investigation is of an empirical nature and it is based on the data that was personally gathered by following a schedule of interviews. Through formal conversation with the business owners of SSEs every attempt has been made to determine the accuracy of the material that has been gathered. In order to accomplish the goals of the research, a field survey was carried out in order to collect primary data. For the purpose of selecting samples, the type of sampling known as simple random sampling was used. The samples that were selected were comprised of business owners of SSEs from the Namakkal District. In each step of the selection process, the lottery method was used as a simple random sampling methodology. The sample size of the study was fixed to be 147 based on the statistical tools that were used in the study. The collected main data that was obtained from the sample small scale units was performed as part of the analysis of the data. The data have been categorised, and cross tabulation has been performed in accordance with the various attributes of the variables. The study has used confirmatory factor analysis using the AMOS software to analyse the challenges faced by the SSE in Namakkal District. The SSEs operating in the study area are highly impacted by the challenges of skilled labor source and lack of appropriate infrastructure to operate their business which has to be resolved by stakeholders involved in policy making.

Coordinated Optimal Operation Method for Snow-Shaped Distribution Networks Based on Game Theory

The snow-shaped distribution network is developed and upgraded from the traditional single-loop network and double-loop network structure. It is composed of three or four groups of single-loop networks in pairs that form a feeder cluster in the form of a ring network. Based on this topology, the coordinated optimization operation problem is studied. First, the game elements are analyzed, and then a cooperative game-based, coordinated optimization operation model is established by taking the minimum network loss and voltage deviation of the system as the utility function. Then, the alternating direction multiplier method (ADMM) is employed in Cplex solver to solve the established optimization model. Finally, a numerical case is given to verify the effectiveness of the proposed model and method. The results show that, by using the complementary difference relationship of source–charge characteristics between different regions in the snow-shaped distribution networks, the cooperative game model can realize the energy interconnection among different regions to improve the operation level.

Late Phase Testicular Torsion in Pre-Geriatic Age: A Case Report

Background: Testicular torsion is a urological emergency caused by a twist of spermatic cord, which result in testicular tissue ischemia and requiring immediate surgery. The incidence occurred generally in children and adolescents, rarely found in adults. Severe Scrotal pain is the most common manifestation of testicular torsion. The definitive treatment for testicular torsion is surgery, either one of orchidopexy or orchidectomy. The prognosis of testicular torsion depends on the onset of symptoms and the decision time for surgery. Case Report: A 52-year-old man presented to emergency department with a history of gradual severe right-sided scrotal pain (visual analogue scale 8) radiated to the right groin in the last 3 day before admission. Previously, the patient's genitals were hit by the table. On physical examination, the testicles were found to be asymmetrical, swollen, redness, tenderness, and the testicle felt hard and immobilized, either the cremaster reflex or the Phren sign test were negative. The TWIST score was 6 (high risk for testicular torsion). Orchidopexy and orchidectomy were performed immediately without Scrotal Doppler Ultrasonography due to operational problems. Histopathology examination of the orchidectomy specimen impression showed an inflammation sign with exudative fluid presentation. Conclusion: Gradual Severe scrotal pain manifestations should be suspected as testicular torsion as soon as possible before it evolves into later phase. One of the causes of late phase testicular torsion is late admission to Hospital. Surgical emergency action should be taken considering theemergency state without waiting for ideal sonography

Exploring the Role of Action Research in Enhancing Quality Management in Teacher Education: A Case Study

The sincere pursuit process called educational research has developed in modern times. Thus, academic research is a systematic activity devoted to discovering and developing well-organized knowledge that always seeks to find or solve a problem. At present, due to the increasing modernization and engineering development in the education system, research has become inevitable in solving operational problems, as well as in the teacher education field, various problems related to teaching and training and action by inventing various developmental approaches in the field of quality management Research. According to Palmer and Johnson (1971), action research is a method of using research for social activities that involve groups of people to solve problems and find root causes, as if the research itself is a part of empowerment and action. This article will explore the inter-dependence of action research and quality management in teacher education.

Optimizing the design and operation of water networks: Two decomposition approaches

We consider the design and operation of water networks simultaneously. Water network problems can be divided into two categories: the design problem and the operation problem. The design problem involves determining the appropriate pipe sizing and placements of pump stations, while the operation problem involves scheduling pump stations over multiple time periods to account for changes in supply and demand. Our focus is on networks that involve water co-produced with oil and gas. While solving the optimization formulation for such networks, we found that obtaining a primal (feasible) solution is more challenging than obtaining dual bounds using off-the-shelf mixed-integer nonlinear programming solvers. Therefore, we propose two methods to obtain good primal solutions. One method involves a decomposition framework that utilizes a convex reformulation, while the other is based on time decomposition. To test our proposed methods, we conduct computational experiments on a network derived from the PARETO case study.

Gossypiboma with enterocutaneous fistula after cesarean section: a case report and review of the literature

IntroductionAlthough precautions taken for surgical procedures are strict and effective in most operative theaters, the incidence of retained foreign bodies following surgery has a reported rate of 0.01–0.001%, of which gossypibomas make up 80% of cases.Case presentationA 42-year-old woman who was Oromo in ethnicity came to the hospital with symptoms of infection, including pus drainage from her lower abdominal incision, fever, chills, and weight loss. Tests indicated an intraabdominal mass consistent with a foreign body from a previous surgery. An exploratory laparotomy revealed a surgical pack causing intestinal perforations. The foreign body was removed, and the patient recovered well postoperatively.ConclusionRetained surgical items are serious problems of surgical operations that can result in morbidity and mortality. Therefore, it should be among the differential diagnoses of any abdominal pain in patients having a history of prior surgery.

The Application of Aluminium- and Natural Clay- Based Compounds in the Treatment of Eutrophicated Waters in Semiarid Brazil

Objective: The presence of cyanobacteria in raw water can affect aquatic biota and human health, as some species are potentially toxic. In addition, these organisms can cause operational problems in water treatment plants, causing interference in the coagulation and flocculation processes, in addition to clogging the filters. The objective of this study was to test the efficiency of the application of poly aluminium chloride (PAC) and aluminium sulphate, with and without association with natural clay, in the removal of total phosphorus, chlorophyll a and cyanobacteria cells in eutrophic reservoir waters of the semi-arid region of Northeast Brazil. Theoretical Framework: The study is based on the application of materials (natural clays) with the capacity to adsorb and precipitate phosphorus from the aquatic environment, blocking its release after sedimentation. This application is efficient in removing sedimentation from cyanobacterial blooms with toxic potential from the aquatic environment Method: This is an experimental study, with tests carried out in Jar Test, with water from a eutrophic environment and with cyanobacteria blooms. Water samples were collected from the subsurface to analyze the parameters: pH, total phosphorus (PT), chlorophyll-a and quantity of cyanobacteria. PT pH and concentration were determined according to the techniques described in Standard Methods APHA (2012). Chlorophyll concentration was analyzed using the extraction technique with 96% ethanol (Jespersen; Christoffersen, 1987). For the qualitative and quantitative study of cyanobacteria, the analysis was carried out using an inverted microscope, according to the methodology of Utermöhl (1958), with sedimentation time in the counting chamber established according to the method of Margalef (1983). The density calculation was carried out according to Ross (1979), being expressed in number of individuals per milliliter (ind. mL-1). Results and Conclusion: The combined application of aluminium sulphate and PAC with natural clay (bentonite) functioned as an efficient technique to remove concentrations of total phosphorus and chlorophyll a, in addition to reducing the density of cyanobacteria. The reduction in the number of cyanobacterial cells with associated application of bentonite and coagulants was promising, with the removal of up to 100% of colonial species and 89% of filamentous species. Implications of the Researsh: The research highlights the relevance of applying low-cost techniques that optimize the quality of water offered for public supply. It should be noted that the presence of cyanobacteria in raw water can affect aquatic biota and human health, as some species have toxigenic potential. Furthermore, these organisms can cause operational problems in water treatment plants, interfering with the coagulation and flocculation processes, in addition to clogging filters. Originaly/Value: This study contributes to the understanding of the application of natural products (clays) as a phosphorus adsorbent and intact cyanobacteria cells. The research highlights that with additional studies, this approach could be a useful tool for removing cyanobacteria cells in water from eutrophic environments intended for public supply.

Borehole disposal of spent fuel and other high-level wastes: the case for deep, vertical, fully cased holes in saturated “hard” rock

Driven by major advances in deep drilling technology and the geological understanding of the deep continental crust over the past 70 years, disposal in deep boreholes has moved from being technically unachievable to the point that it now offers a viable solution for the most hazardous nuclear wastes that could effectively be implemented “tomorrow”—i.e., within a few years. Moreover, disposal in deep boreholes is arguably superior in almost every respect to the mined and engineered repositories being pursued for high level waste by most countries. During the first 50 years of their evolution, almost all deep borehole disposal concepts shared five key aspects: (i) the hole was as deep as possible, (ii) it was vertical, (iii) it was fully cased, and (iv) it was in “hard” basement rock (v) saturated with aqueous fluid (groundwater). Technical advances in drilling over the last 20 years have encouraged proposed versions of the concept which depart from one or more of these aspects, but it is our contention that all five fundamental aspects should be retained. This paper summarises the more important arguments supporting this view. In order to meet the necessary post-closure (radiological) safety requirements, engineer out possible operational problems during construction and waste-package deployment, and capitalise on the main benefits of borehole disposal, the hole itself must be over 3 km deep, vertical, fully cased, and in suitably hard (ideally granitic) host rock saturated with aqueous fluid.

GRU-IKF scene taxiing trajectory prediction model based on attention mechanism

Aircraft taxi trajectory prediction helps solve operational problems such as airport taxiing conflicts and long waiting times, ensuring airport safety while improving service levels and increasing airport throughput. In view of the fact that the performance of machine learning models depends on good data sets, a method for predicting taxi trajectories of aircraft on the ground based on attention mechanism, fusion of gated recurrent unit (GRU) and improved Kalman filter algorithm (IKF) is proposed. Firstly, three independent gated recurrent unit networks are used to capture the motion state and temporal dependency of aircraft at future moments, and the attention mechanism is introduced to enhance the ability to extract data difference features and learn the mapping relationship from input to output; then, it is fused with the improved extended Kalman filter to integrate the output results of the neural network into the state prediction and update process to improve the accuracy of the predicted trajectory sequence. Finally, the effectiveness of the model was verified using the actual taxiing trajectory of aircraft at Lukou Airport. The simulation results show that the model can effectively and accurately predict the taxiing trajectory of aircraft on the surface, with an overall mean square error of about 0.00128. Compared with the single recurrent neural network (RNN), long short-term memory network (LSTM) and GRU model, the RMSE is reduced by 72.9%and respectively 39.9%, 54.7%and the prediction time is 40 ms. It can accurately and quickly predict the taxiing trajectory, which helps to reduce the operating load of the airport surface management system.

Peran External Relation PT KCI Dalam Upaya Meningkatkan Corporate Image

The role of PT KCI's External Relations in efforts to improve its Corporate Image is important to provide a positive view of the public. This cannot be separated from how External Public Relations carries out its role with a managerial concept. This research aims to analyze the role of PT KCI's external public relations. This research uses the concept of Managerial roles. This research method uses qualitative methods, the data collection techniques used are interviews, observation and documentation. The results of this research found the role of External Relations in improving corporate image with expert communication experts, problem-solving process facilitators, communication facilitators and communication technicians. And the obstacles include internal and external obstacles, including operational problems, crisis communication, public and media perceptions, technological challenges, internal challenges, changes in government policy and social issues. The results of this analysis provide insight into the dynamics of the role of PT KCI's external public relations in efforts to improve its corporate image.

Overview and suggestion about Chinese health-related non-governmental organization's participation in global health governance

Non-governmental organization (NGO) is one of the important non-state actors in global health governance. The importance of NGO's participation in the global health governance tend to be more prominent due to its flexibility, professionalism, voluntariness and autonomy. The World Health Organization (WHO) established a Civil Society Commission (CSC) in 2023 aiming at strengthening dialogue, facilitating collaboration so as to play its bigger role in the global health governance. This paper is to make analysis to the importance of NGO in global health governance, WHOCSC's organizational structure and operational mechanism, current status and problem of Chinese health-related NGO's participation in the global health governance, and to provide policy suggestions for strengthening Chinese health-related NGOs' participation in global health governance, including incubating Chinese NGOs into national strategy for global health, strengthening resources mobilization and coordination, as well as advocating transparency and society involvement, emphasizing international humanitarian, public welfare and propaganda.

Measurement of Information System Quality Management using ISO 9001:2015 Standards at PT Bersama Kita Besar

Operational problems related to performance evaluation within the company are the background for this research. Data was collected through interviews with the chief auditor, a 4-item questionnaire for the head of IT and 3 IT staff, and observations of company documents and staff performance. The questionnaire used a Likert scale, and the overall assessment applied the Maturity Model. Results indicated that PT. Bersama Kita Besar achieved a level 3 (Defined Process) in maturity. Small improvements are needed to reach levels 4 and 5, such as enhancing staff performance through training and adding competent human resources. The study focused on the IT division of PT Bersama Kita Besar, using clauses 4 to 10 of ISO 9001:2015 for measurement. These results can support the company's ISO 9001:2015 certification efforts and ongoing improvements.

Optimizing fleet, staff configuration and operational strategies in one-way mixed fleet carsharing systems: a Lagrangian relaxation-based approach

ABSTRACT This study explores enhancing carsharing services by integrating gasoline and electric vehicles into a one-way mixed fleet carsharing system (OMFCS). The focus is on optimizing configurations (fleet and staff size, initial deployment) and operational strategies (vehicle relocation and staff rebalancing) while considering carbon emission costs. Employing a space-time-electricity network modeling approach, we developed an integer linear programming model to tackle the configurations and operational strategies optimization problem. For solving this model, we introduce a Lagrangian relaxation-branch bound approach, which integrates subgradient, dynamic programming and greedy-based heuristics algorithm. An illustrative case and a real-world case are conducted to demonstrate the efficiency of the proposed solution method and the analysis sheds light on the configurations and operational strategies of OMFCS. The sensitive analysis results suggest that OMFCS is more profitable and balances user service quality and carbon emissions better than carsharing systems using only one type of vehicle.

Investigating the lived experiences of persons who were sentenced to the Substance Abuse Felony Punishment Facility: a qualitative study

The Texas Substance Abuse Felony Punishment Facility (SAFPF) is a part of the Texas Department of Criminal Justice (TDCJ) aimed at reducing crime by treating substance use disorders for individuals with felony charges. This work investigates the lived experience and shared themes of persons who attended SAFPF (N = 8) using phenomenological qualitative methods. The results highlight many strengths including connection through relationships, self-motivation, and aftercare options. Reported weaknesses included treatment provision, curriculum deficits, and operational problems. Results found numerous positive and negative aspects of the person’s lived experience that could inform policy and treatment methods of future SAFPF programs.

Stochastic dual dynamic programming for optimal power flow problems under uncertainty

Planning in the power sector has to take into account the physical laws of alternating current (AC) power flows as well as uncertainty in the data of the problems, both of which greatly complicate optimal decision making. We propose a computationally tractable framework to solve multi-stage stochastic optimal power flow (OPF) problems in AC power systems. Our approach uses recent results on dual convex semi-definite programming (SDP) relaxations of OPF problems in order to adapt the stochastic dual dynamic programming (SDDP) algorithm for problems with a Markovian structure. We show that the usual SDDP lower bound remains valid and that the algorithm converges to a globally optimal policy of the stochastic AC-OPF problem as long as the SDP relaxations are tight. To test the practical viability of our approach, we set up a case study of a storage siting, sizing, and operations problem. We show that the convex SDP relaxation of the stochastic problem is usually tight and discuss ways to obtain near-optimal physically feasible solutions when this is not the case. The algorithm finds a physically feasible policy with an optimality gap of 3% and yields a significant added value of 27% over a rolling deterministic policy, which leads to overly optimistic policies and underinvestment in flexibility. This suggests that the common industry practice of assuming direct current and deterministic problems should be reevaluated by considering models that incorporate realistic AC flows and stochastic elements in the data as potentially more realistic alternatives.

Conjunctive optimal operation of water and power networks

Water distribution systems (WDSs) are designed to convey water from sources to consumers. Their operation is a main concern for engineers, researchers, and practitioners and is subject to demand, pressure, and quality constraints. Pumping stations require power to pump water and keep system pressure at a desired level. On the other hand, power is generally supplied through power grids (PGs), which require optimal operation while satisfying operational constraints, such as generation limits, power consumption, and voltage constraints. Since the two infrastructure systems are interconnected, decision-makers could benefit from a holistic approach that would allow solving the two operational optimization problems together as one conjunctive problem. This paper presents the full mathematical formulation of the conjunctive optimization problem, including a novel modelling approach for the operation of a variable speed pump, which does not include integer variables for pump status, thus allowing to solve the model as a non-linear programming (NLP) problem. The formulation is applied to two illustrative case studies, and the results are compared to the optimal operation of the independent WDS. The inclusion of the PG in the optimization problem is observed clearly in the results and influences them quite significantly. WDS operation is shown adjust to the PG constraints, and the application of the conjunctive model results in a cost reduction rate of more than 10 % for both case studies.