Combined Operation Research Articles

Large-scale off-grid wind power hydrogen production multi-tank combination operation law and scheduling strategy taking into account alkaline electrolyzer characteristics

This paper proposes a multi-electrolyzer switching scheduling strategy based on the Pelican Optimization Algorithm (POA) to enhance the efficiency of large-scale wind power hydrogen production systems. To validate the effectiveness of the proposed strategy, we analyzed wind power data from three typical days in northern Hebei, China, with a 2.5 MW wind turbine output. We designed three strategies for comparative analysis: a simple start-stop strategy, a rule-based multi-electrolyzer switching strategy, and a POA-based multi-electrolyzer switching strategy. The study results demonstrate that the POA-based strategy exhibits higher hydrogen production efficiency and system stability under various wind conditions. Particularly, in extreme wind scenarios, this strategy significantly reduces the start-stop cycles of electrolyzers, thereby lowering operational costs and improving overall system performance. The main contribution of this study lies in the novel optimization algorithm and its validation through real-world data, demonstrating its effectiveness in large-scale wind power hydrogen production systems. Our findings provide new insights for enhancing the utilization of renewable energy and the economics of hydrogen production systems.

Space-time symmetry and nonreciprocal parametric resonance in mechanical systems.

Linear mechanical systems with time-modulated parameters can harbor oscillations with amplitudes that grow or decay exponentially with time due to the phenomenon of parametric resonance. While the resonance properties of individual oscillators are well understood, those of systems of coupled oscillators remain challenging to characterize. Here we determine the parametric resonance conditions for time-modulated mechanical systems by exploiting the internal symmetries arising from the real-valued and symplectic nature of classical mechanics. We also determine how these conditions are further constrained when the system exhibits external symmetries. In particular, we analyze systems with space-time symmetry where the system remains invariant after a combination of discrete translation in both space and time. For such systems, we identify a combined space-time translation operator that provides more information about the dynamics of the system than the Floquet operator does and use it to derive conditions for one-way amplification of traveling waves. Our exact theoretical framework based on symmetries enables the design of exotic responses such as nonreciprocal transport and one-way amplification in dynamic mechanical metamaterials and is generalizable to all physical systems that obey space-time symmetry.

Optimization algorithms for transmit waveform design in radar-centric dual-function radar-communication systems

We study the transmit waveform optimization problem in multiple-input-multiple-output (MIMO) dual-function radar-communication (DFRC) systems. A penalty-based formulation is adopted where engineering concerns on radar and communication are integrated in a weighted manner. We transform the original problem into an unconstrained formulation and propose a novel waveform synthesis algorithm via combination of multiple algorithm updates. The combination operation experimentally reaches a better objective value than without. We develop two combination strategies and invent a shrinkage-expansion line search method for monotonicity maintenance. Numerical experiments show that the proposed algorithm suffices to generate constant modulus waveforms which achieve radar and communication purposes.

Combining Metabolomics and Machine Learning to Identify Diagnostic and Prognostic Biomarkers in Patients with Non-Small Cell Lung Cancer Pre- and Post-Radiation Therapy.

Lung cancer is the leading cause of cancer-related deaths globally, with non-small cell lung cancer (NSCLC) accounting for over 85% of cases and poor prognosis in advanced stages. This study explored shifts in circulating metabolite levels in NSCLC patients versus healthy controls and examined the effects of conventionally fractionated radiation therapy (CFRT) and stereotactic body radiation therapy (SBRT). We enrolled 91 NSCLC patients (38 CFRT and 53 SBRT) and 40 healthy controls. Plasma metabolite levels were assessed using semi-targeted metabolomics, revealing 32 elevated and 18 reduced metabolites in patients. Key discriminatory metabolites included ethylmalonic acid, maltose, 3-phosphoglyceric acid, taurine, glutamic acid, glycocolic acid, and d-arabinose, with a combined Receiver Operating Characteristics curve indicating perfect discrimination between patients and controls. CFRT and SBRT affected different metabolites, but both changes suggested a partial normalization of energy and amino acid metabolism pathways. In conclusion, metabolomics identified distinct metabolic signatures in NSCLC patients with potential as diagnostic biomarkers. The differing metabolic responses to CFRT and SBRT reflect their unique therapeutic impacts, underscoring the utility of this technique in enhancing NSCLC diagnosis and treatment monitoring.

Descriptional Complexity of Finite Automata – Selected Highlights

The state complexity, respectively, nondeterministic state complexity of a regular language L is the number of states of the minimal deterministic, respectively, of a minimal nondeterministic finite automaton for L. Some of the most studied state complexity questions deal with size comparisons of nondeterministic finite automata of differing degree of ambiguity. More generally, if for a regular language we compare the size of description by a finite automaton and by a more powerful language definition mechanism, such as a context-free grammar, we encounter non-recursive trade-offs. Operational state complexity studies the state complexity of the language resulting from a regularity preserving operation as a function of the complexity of the argument languages. Determining the state complexity of combined operations is generally challenging and for general combinations of operations that include intersection and marked concatenation it is uncomputable.

Low-carbon optimal dispatch strategy of power systems considering the combined operation of oxy-fuel combustion and electric hydrogen production

ABSTRACT Oxy-fuel combustion technology offers a promising solution for achieving nearly zero carbon dioxide emissions from coal-fired units, presenting a viable path toward low-carbon dispatch. This study establishes a simulation model for the low-carbon operation of power systems, focusing on the integrated operation of an oxy-fuel combustion plant and electric hydrogen production. By incorporating oxygen generated from electric hydrogen production into the oxy-fuel combustion plant, the primary objective is to minimize system operation costs. Through simulation analysis and verification, a comparative scenario is constructed to evaluate performance. The simulation results indicate that the joint operation approach yields significant benefits. In comparison to separate operation, the joint operation strategy leads to a reduction of approximately 7.38% in total system costs, 18.79% in operating costs, and 23.56% in carbon emissions. This integrated approach not only achieves lower carbon emissions but also results in reduced overall system costs.

Improving processing efficiency through workflow process reengineering, simulation and value stream mapping: a case study of business process reengineering

PurposeBusiness Process Reengineering (BPR) eliminates non-value-added (NVA) and essential non-value-added (ENVA) waste through radical process redesign to improve organizational operations. Comprehensive research integrating BPR tools is needed to understand their benefits for manufacturing firms. This research presents an integrated BPR-simulation framework tailored to the manufacturing sector to maximize process improvements and operational excellence.Design/methodology/approachThe BPR design methodology adopts a systematic, multi-stage approach. The first phase involves identifying a specific improvement process aligned with BPR's core objectives. This phase analyses and redesigns workflows to optimize task sequences, roles, and stakeholder interactions while eliminating redundancies and inefficiencies via Workflow Process Reengineering. Visual process mapping tools, including VSM and simulation, pinpoint areas of waste, delay, and potential enhancement. The second phase follows the workflow analysis and aims to improve efficiency and effectiveness by redefining roles, rearranging tasks, and integrating automation and technology solutions. The redesigned process undergoes evaluation against key performance indicators to ensure measurable improvements are achieved. The final phase validates the proposed changes through simulation models, assesses the impact on key performance metrics, and establishes the necessary infrastructure for successful implementation. The proposed model is empirically validated through a case study of a leading apparel company in Vietnam, confirming its effectiveness.FindingsThe findings reveal that NVA activities are being eliminated, and ENVA activities in key departments are significantly reduced. This yielded a substantial improvement, reducing 25 out of 186 combined ENVA and NVA operations in the sewing facility, involving a decrease of 15 ENVA operations and the removal of 10 NVA operations. Consequently, this led to an 8.5% reduction in the proportion of ENVA operations, accompanied by a complete 100% elimination of NVA activities.Research limitations/implicationsThe single case study limits generalizability; thus, expanded implementation across diverse manufacturing sub-sectors is required to establish validity and broader applicability of the integrated framework.Originality/valueThe experimental results highlight the proposed model's effectiveness in optimizing resource utilization and its practical implementation potential. This structured BPR methodology enables organizations to validate, evaluate, and establish proposed process changes to enhance operational performance and productivity.

Pattern classification of bearing faults in PMSM based on time domain feature ensembles

This research aims to identify an effective feature-based pattern classification technique that uses vibration and current data to identify bearing conditions. The authors attempted non-conventional time-domain features to detect the bearing conditions in permanent magnet synchronous motors (PMSM). This work employs two case studies utilizing eight datasets from Paderborn University to identify the bearing conditions of three and twelve classes. In this work, support vector machine, k-nearest neighbor, random forest, decision tree, and naive Bayes classifiers with 10% holdout validation are applied to study 31 feature combinations. This study also examines the Henry gas solubility optimization technique for feature selection to identify the most discriminating features. The results indicate that four feature ensembles consisting of 2 to 5 features performed better with the support vector machine, k-nearest neighbor, and random forest classifiers. In contrast to previous relevant studies, the proposed features are useful in identifying PMSM-bearing conditions with the highest accuracy of 99.8% and 99% using current signals for 3 and 12 classes respectively for combined current operating conditions.

The combination operation of grouping and ensemble coding for structured biological motion crowds in working memory

Massive studies have explored biological motion (BM) crowds processing for their remarkable social significance, primarily focused on uniformly distributed ones. However, real-world BM crowds often exhibit hierarchical structures rather than uniform arrangements. How such structured BM crowds are processed remains a subject of inquiry. This study investigates the representation of structured BM crowds in working memory (WM), recognizing the pivotal role WM plays in our social interactions involving BM. We propose the group-based ensemble hypothesis and test it through a member identification task. Participants were required to discern whether a presented BM belonged to a prior memory display of eight BM, each with distinct walking directions. Drawing on prominent Gestalt principles as organizational cues, we constructed structured groups within BM crowds by applying proximity and similarity cues in Experiments 1 and 2, respectively. In Experiment 3, we deliberately weakened the visibility of stimuli structures by increasing the similarity between subsets, probing the robustness of results. Consistently, our findings indicate that BM aligned with the mean direction of the subsets was more likely to be recognized as part of the memory stimuli. This suggests that WM inherently organizes structured BM crowds into separate ensembles based on organizational cues. In essence, our results illuminate the simultaneous operation of grouping and ensemble encoding mechanisms for BM crowds within WM.

Fixed parotid sialoliths: surgical treatment via transfacial approach using sialendoscopy and ultrasound guidance—retrospective cohort study

The most common cause of symptomatic parotitis is the obstruction of its duct, most commonly by a stone. Despite the development of minimally invasive endoscopic techniques, some of these obstructions cannot be treated entirely endoscopically, requiring combined approaches. This study reviewed the outcomes and surgical technique of ultrasound-guided transfacial parotid sialolithotomy following a failed endoscopic approach. Conducted as a case series with retrospective chart review at an academic tertiary care center, the study evaluated patients who underwent this combined transfacial-endoscopic operation for symptomatic parotid sialolithiasis from April 2022 through January 2023. Key outcomes included operative technique, stone size, stone location, complications, and symptom relief. A total of four male patients with a mean age of 66 years underwent the ultrasound-guided transfacial operation for symptomatic parotid sialolithiasis. Needle localization facilitated transfacial stone retrieval in all cases. The follow-up period ranged from 6 to 15 months. Stone locations included the proximal one-third of the ductal lumen (1 patient), the parotid hilum (1 patient), and within the gland parenchyma (2 patients). The average sialolith length was 8 ± 1.4 mm, and the width was 3 ± 0.8 mm. The average surgical time was 113 ± 16.5 minutes. All cases (100%) achieved successful stone retrieval and symptomatic improvement, with complete resolution of symptoms in 3 cases (75%). No major complications were reported. Ultrasound-guided transfacial parotid sialolithotomy is a safe and effective alternative to parotidectomy for patients who have failed a purely endoscopic approach. A novel transfacial surgical dissection method, based on the middle premasseter space, is proposed for accessing the main parotid duct when obstructions are located in the middle portion of the duct.

The AUKUS agreement: a new form of the plurilateral defence alliance? A view from downunder

ABSTRACT In 2021, Australia, the United Kingdom, and the United States announced a multi-decade programme – dubbed AUKUS – for tripartite collaboration in the development of nuclear-powered submarines and other advanced military capabilities. This article explores the extent to which AUKUS signals a departure from a spectrum of US-centred international security arrangements ranging from a plurilateral model, as exemplified by the North Atlantic Treaty Organisation (NATO), to the bilateral (hub-and-spoke) model more common in the Indo-Pacific. The paper argues that AUKUS complements US-centred protective arrangements along NATO and hub-and-spoke lines. In leveraging US technological leadership and military investments to enhance partner-specific military capabilities, and AUKUS breaks new ground, being less about deterrence of, and military responses to, an attack aggression on one or more of its members, and more about enhancing interoperability, combined operational s/synergy, and reciprocity in new capability formation by the parties. The work concludes that the AUKUS arrangements stand to provide less scope for free-riding by the parties, while giving them greater incentive to invest in interoperable military capabilities, thereby creating more contingent (real) deployment options for the future, US-led combined military operations, to be exercised by the parties in response to emergent military contingencies.

Combination of dependent and partially reliable Gaussian random fuzzy numbers

Gaussian random fuzzy numbers are random fuzzy sets generalizing Gaussian random variables and possibility distributions. They define belief functions on the real line that can be conveniently combined by the product-intersection rule under the independence assumption. In this paper, we introduce various extensions of this rule to account for dependence and partial reliability of the pieces of evidence. We first provide formulas for the combination of an arbitrary number of Gaussian random fuzzy numbers whose dependence is described by a correlation matrix, and we introduce a minimum-conflict combination operation. To account for partially reliable evidence, we then introduce two discounting operations called possibilistic and evidential discounting, as well as several combination operators based on different assumptions, each one parameterized by a correlation matrix and a vector of discounting coefficients. We demonstrate the application of these operators to the combination of predictions with different sets of inputs in machine learning, and show that performance can be enhanced by optimizing the parameters of the combination operators.

Improving safety design for gas pipeline installation via horizontal directional drilling: a pipe stress analysis approach

Horizontal Directional Drilling (HDD) has today emerged as a significant and efficient Horizontal Directional Drilling (HDD) has today emerged as a significant and efficient technique for installing pipelines for a variety of purposes, including the production of oil, natural gas, water, sewer, electrical, and telecommunications. Due to the complexity of the technology and the intricate interplay of numerous processes, the safety risks associated with process uncertainty are substantial. However, risk analysis for HDD projects is generally done using qualitative methods. One of the most common factors used for HDD risk assessment is Pipe Stress Analysis (PSA). In this article, a combination of material evaluation and PSA for HDD safety design is suggested to improve the risk analysis. The evaluation will commence with an assessment of the material, followed by an examination of the wall thickness. Subsequently, an analysis of HDD design and pipe stress will be conducted. Using 10-inch API 5L Gr. B pipe, the safety design was successfully tested for a gas pipe project. When using HDD, a natural bend value of no less than 415.3 meters must have a horizontal length of 168 meters. According to the curvature, the length of the entire pipe is 169.03 meters. The combined installation stress was less than 1, while the combined operation stress was 114.87 MPa. These two values met the criteria specified in the standard. Overall, those steps were able to ensure that the HDD installation design is safe for construction.

A microgrid control scheme for islanded operation and re-synchronization utilizing Model Predictive Control

Enhancing grid resilience is proposed through the integration of distributed energy resources (DERs) with microgrids. Due to the diverse nature of DERs, there is a need to explore the optimal combined operation of these energy sources within the framework of microgrids. As such, this paper presents the design, implementation and validation of a Model Predictive Control (MPC)-based secondary control scheme to tackle two challenges: optimal islanded operation, and optimal re-synchronization of a microgrid. The MPC optimization algorithm dynamically adjusts input signals, termed manipulated variables, for each DER within the microgrid, including a gas turbine, an aggregate photovoltaic (PV) unit, and an electrical battery energy storage (BESS) unit. To attain optimal islanded operation, the secondary-level controller based on Model Predictive Control (MPC) was configured to uphold microgrid functionality promptly following the islanding event. Subsequently, it assumed the task of power balancing within the microgrid and ensuring the reliability of the overall system. For optimal re-synchronization, the MPC-based controller was set to adjust the manipulated variables to synchronize voltage and angle with the point of common coupling of the system. All stages within the microgrid operation were optimally achieved through one MPC-driven control system, where the controller can effectively guide the system to different goals by updating the MPC’s target reference. More importantly, the results show that the MPC-based control scheme is capable of controlling different DERs simultaneously, mitigating potentially harmful transient rotor torques from the re-synchronization as well as maintaining the microgrid within system performance requirements.

Analysis of the efficacy of left subclavian artery laser in situ fenestration combined with hybrid arch debranching surgery for aortic arch reconstruction in patients with Stanford type A aortic dissection

Objective: To observe the short-and mid-term efficacy of left subclavian artery(LSA) laser in situ fenestration combined with arch debranching surgery for aortic arch reconstruction in patients with Stanford type A aortic dissection aged 60 years and above. Methods: This is a retrospective cohort study. A total of 41 Stanford type A aortic dissection patients aged 60 years and above who received combined surgery in Department of Endovascular Surgery, the First Affiliated Hospital of Zhengzhou University from January 2018 to December 2020 were retrospectively analyzed. There were 25 males and 16 females, aged (67.3±5.9)years(range: 60 to 75 years). Among them, 19 patients underwent LSA laser in situ fenestration combined with arch debranching surgery(combined surgery group) and 22 patients underwent hybrid aortic arch debranching surgery(non-combined surgery group). Independent sample t test, χ2 test and Fisher exact probability method were used to compare the clinical characteristics of the two groups. Kaplan-Meier method was used for survival analysis, and the 5-year survival rate of the two groups was compared by Log-rank test. Results: Body mass index in the combined operation group was significantly higher than that in the non-combined operation group ((27.1±1.6)kg/m2 vs.(26.9±1.9)kg/m2; t=2.766,P=0.006), and the difference was statistically significant. There was no statistical significance in the comparison of other general data (all P>0.05). The operation time ((321.3±11.4) minutes vs. (329.6±7.3)minutes; t=-2.733, P=0.010) and LSA reconstruction time ((32.4±3.0)minutes vs. (42.4±6.0)minutes; t=-6.842, P<0.01) in the combined operation group were significantly shortened, and the difference was statistically significant. The rate of LSA reconstruction in the combined operation group (100% vs. 72.7%; P=0.023) was significantly higher than that in the non-combined operation group, and the difference was statistically significant. There were no significant differences in the incidence of pulmonary infection, unplanned second operation, continuous renal replacement therapy, neurological complications and the in-hospital mortality between the two groups. Compared with the non-combined surgery group, the total complication rate related to LSA reconstruction was significantly lower in the combined surgery group (0 vs. 27.3%; P=0.023). Kaplan-Meier survival analysis showed that there was no difference in 5-year survival rate between the combined operation group and the non-combined operation group (84.2% vs. 77.3%; χ2=0.310, P=0.578). Conclusion: Laser in situ fenestration of the LSA combined with arch debranching surgery to reconstruct the aortic arch can significantly shorten the operation and LSA reconstruction time in patients aged 60 years and above with Stanford type A aortic dissection, improve the success rate of LSA reconstruction, and reduce the occurrence rate of LSA reconstruction complications.

Reducing Energy Consumption in the Synthesis of Dimethyl Ether (DME) from Methanol Dehydration by Modifying Heat Transfer Unit Using Aspen HYSYS

In the pursuit of a transport sector free from fossil fuels, the incorporation of Dimethyl ether (DME) emerges as a commendable ecological substitute. The DME is a synthetically produced serves as a viable alternative to conventional fuels such as diesel and liquified petroleum gas (LPG). The Dimethyl Ether (DME) production is carried out by catalytic dehydration of methanol over an acidic zeolite-based catalyst. The technological process for the DME synthesis was simulated using Aspen HYSYS based on the combined operating parameters of the reaction dynamic model for the methanol dehydration reaction. This paper attempts to evaluate a modification in dehydration of methanol process to reducing energy consumption by modifying heat transfer unit. The heater and cooler heat transfer units were converted into heat exchangers (HE) by utilizing the output of the process that can be used for other processes so that energy consumption is reduced. The temperature of reaction and the heat transfer unit are modified to reduce energy consumption from 11.850 MMBtu/h to 7.6291 MMBtu/h by changing one heater and one cooler with two heat exchangers. Copyright © 2024 by Authors, Published by Universitas Diponegoro and BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Future Perspective of Risk Prediction in Aesthetic Surgery: Is Artificial Intelligence Reliable?

Artificial intelligence (AI) techniques are showing significant potential in the medical field. The rapid advancement in artificial intelligence methods suggests their soon-to-be essential role in physicians' practices. In this study, we sought to assess and compare the readability, clarity, and precision of medical knowledge responses provided by 3 large language models (LLMs) and informed consent forms for 14 common aesthetic surgical procedures, as prepared by the American Society of Plastic Surgeons (ASPS). The efficacy, readability, and accuracy of 3 leading LLMs, ChatGPT-4 (OpenAI, San Francisco, CA), Gemini (Google, Mountain View, CA), and Copilot (Microsoft, Redmond, WA), was systematically evaluated with 14 different prompts related to the risks of 14 common aesthetic procedures. Alongside these LLM responses, risk sections from the informed consent forms for these procedures, provided by the ASPS, were also reviewed. The risk factor segments of the combined general and specific operation consent forms were rated highest for medical knowledge accuracy (P < .05). Regarding readability and clarity, the procedure-specific informed consent forms, including LLMs, scored highest scores (P < .05). However, these same forms received the lowest score for medical knowledge accuracy (P < .05). Interestingly, surgeons preferred patient-facing materials created by ChatGPT-4, citing superior accuracy and medical information compared to other AI tools. Physicians prefer patient-facing materials created by ChatGPT-4 over other AI tools due to their precise and comprehensive medical knowledge. Importantly, adherence to the strong recommendation of ASPS for signing both the procedure-specific and the general informed consent forms can avoid potential future complications and ethical concerns, thereby ensuring patients receive adequate information.

Long-term outcomes of isolated mechanical versus bioprosthetic mitral valve replacement in different age groups of propensity-matched patients.

Prothesis choice in isolated mitral valve replacement for patients aged 75 years or younger remains debated as most studies comparing prothesis type have included large proportions of combined operations and benefits are influenced by concomitant procedures. This study compared long-term outcomes of isolated mechanical versus bioprosthetic mitral valves in different age groups of propensity-matched populations. This is a retrospective, multicentre, propensity-matched observational study. Baseline characteristics, operative details and long-term outcomes (mortality and freedom from surgical/transcatheter reintervention) were collected. Totally, 1536 isolated mitral valve replacements (806 mechanical, 730 bioprosthetic) were performed between 2000 and 2017. Over 90% of eligible patients successfully underwent propensity matching, yielding 226 each of mechanical and bioprosthetic valves in patients aged <65 years and 171 each of bioprosthetic and mechanical valves in patients aged 65-75 years with median follow-up of 13 years (maximum 20 years). In matched patients <65 years, 10-year survival was superior with mechanical valves versus bioprosthetic valves (78.2% vs 69.8%, P = 0.029), as was 10-year freedom from reintervention (96.2% vs 81.3%, P < 0.001). For matched patients between 65 and 75 years, there were no differences between mechanical and bioprosthetic valves in 10-year survival (64.6% vs 60.8%, P = 0.86) or 10-year freedom from reintervention (94.0% vs 97.2%, P = 0.23). Rates of post-operative stroke, gastrointestinal bleeding, renal failure and permanent pacemaker insertion were similar. In patients requiring isolated mitral valve replacement, mechanical valves confer significantly better long-term survival and freedom from reintervention for patients <65 years, while no benefit is observed at age 65-75 years compared to bioprosthetic valves.

Entanglement and pseudo entanglement dynamics versus fusion in CFT

The fusion rules and operator product expansion (OPE) serve as crucial tools in the study of operator algebras within conformal field theory (CFT). Building upon the vision of using entanglement to explore the connections between fusion coefficients and OPE coefficients, we employ the replica method and Schmidt decomposition method to investigate the time evolution of entanglement entropy (EE) and pseudo entropy (PE) for linear combinations of operators in rational conformal field theory (RCFT). We obtain a formula that links fusion coefficients, quantum dimensions, and OPE coefficients. We also identify two definition schemes for linear combination operators. Under one scheme, the EE captures information solely for the heaviest operators, while the PE retains information for all operators, reflecting the phenomenon of pseudo entropy amplification. Irrespective of the scheme employed, the EE demonstrates a step-like evolution, illustrating the effectiveness of the quasiparticle propagation picture for the general superposition of locally excited states in RCFT. From the perspective of quasiparticle propagation, we observe spontaneous block-diagonalization of the reduced density matrix of a subsystem when quasiparticles enter the subsystem.

Timing Considerations for Sleeve Gastrectomy in Kidney Transplant Patients: A Single Center Evaluation.

Current scientific literature is deficient in detailing the optimal timing for conducting bariatric surgery in relation to kidney transplantation. In this study, we performed a retrospective evaluation of kidney transplant recipients with BMI >35kg/m2. It aimed to provide data on those who received both sleeve gastrectomy (SG) and kidney transplantation (KT) simultaneously, as well as on patients who underwent SG and KT at different times, either before or after. In addition, the acceptance levels of the bariatric surgery among different scenarios were assessed. Our findings demonstrated that combined KT and SG led to successful weight loss, in contrast to undergoing kidney transplant alone, while maintaining comparable rates of graft and patient survival. Weight loss was similar between recipients who had a combined operation and those who underwent SG following the transplant. Additionally, over a median time frame of 1.7 years, patients who underwent SG before KT exhibited a statistically significant reduction in BMI at the time of the transplant. Notably, our study highlights that patients offered the combined procedure were significantly more likely to undergo SG compared to those for whom SG was presented at a different operative time than the transplant.