Numerous Limitations Research Articles

A review on the microgrid sizing and performance optimization by metaheuristic algorithms for energy management strategies

A growing concern over climate change and the depletion of conventional energy resources have led to the urgent need for sustainable and resilient energy solutions. The optimization of the size of renewable sources is crucial to maximizing their effectiveness. In contrast to conventional single-objective optimization, the multi-objective technique aims to achieve a trade-off between energy cost and power supply reliability. Due to this need, microgrids (MG) have emerged as a promising paradigm, allowing for localized and decentralized energy generation and distribution. Consequently, the conventional techniques for modelling and optimizing exhibit numerous limitations as the power grid continues to produce substantial volumes of high-dimensional and diverse data types. This review paper examines the use of metaheuristic algorithms in the context of multi-objective energy optimization for hybrid renewable energy-integrated microgrids. A comparative analysis of diverse metaheuristic algorithms for microgrid optimization is provided in this paper, which emulates natural phenomena, such as evolutionary processes and swarm dynamics. Based on the findings of case studies, it can be concluded that trade-offs exist between various objectives, eventually leading to the development of both resilient and efficient microgrid designs. By reviewing sustainable energy solutions, and advocating microgrids as viable alternatives to conventional centralized power systems, the review enhances the advancement of sustainable energy solutions.

Numerical Limit Analysis of Stability for a Soil Slope in Shenzhen

Numerical Limit Analysis of Stability for a Soil Slope in Shenzhen

Pharmacological methods for ovarian function and fertility preservation in women with cancer: A literature review.

Oncofertility is an extremely significant topic that is increasingly being discussed owing to increased evidence indicating that fertility preservation does not affect the treatment outcomes of patients with cancer but significantly contributes to preserving life quality. The effect of chemotherapy can range from minimal effects to complete ovarian atrophy. Limited data are available on the effects of monoclonal antibodies and targeted therapies on the ovaries and fertility. Temporary ovarian suppression by administering a gonadotropin-releasing hormone agonist (GnRHa) during chemotherapy decreases the gonadotoxic effect of chemotherapy, thereby diminishing the chance of developing premature ovarian insufficiency (POI). At present, the concomitant administration of GnRH analogs during chemotherapy is the only accepted pharmacological method for preserving ovarian function. Notably, most randomized studies on the effectiveness of luteinizing hormone-releasing hormone agonists during chemotherapy in preventing POI have been conducted in women with breast cancer, with a considerably small number of studies on patients with hematological malignancies. Furthermore, most randomized controlled trials on breast cancer have revealed a decrease in treatment-induced POI risk, regardless of the hormone receptor status. In addition, studies on hematological malignancies have yielded negative results; nevertheless, the findings must be interpreted with caution owing to numerous limitations. Current guidelines from the American Society of Clinical Oncology and ESMO Clinical Practice Guidelines recommend sperm, oocyte, and embryo cryopreservation as a standard practice and only offering GnRHa to patients when proven fertility preservation methods are not feasible. In this manuscript, we present a comprehensive literature overview on the application of ovarian suppression with GnRHa during chemotherapy in patients with cancer by addressing preclinical and clinical data, as well as future perspectives in this field that upcoming research should focus on.

Life cycle analysis of sediment valorization by means of geopolymerization from laboratory to industrial scale

Geopolymerization has become a potential competitor to cement over the last 10 years due to its lower carbon impact. However, the development of geopolymerized applications on an industrial scale still faces numerous limits. As an answer, the valorisation of local sources of materials such as dredged sediment as precursors has been identified in the literature of high interest as it could solves sediment management problems as well as reducing geopolymerization environmental and economic cost. Therefore, this study evaluates, through a Life Cycle Analysis (LCA), the impact of mortars developed from untreated dredged sediments mixed with cement or alkalis. The solutions developed in the laboratory were transposed to a hypothetical industrial scale around the Port of Bordeaux area. Four mortars were compared with equivalent mechanical resistance: a classic Ordinary Portland Cement (OPC) mortar and three geopolymer mortars with NaOH and Na2SiO3 alkalis. Results showed that, compared to the use of cement, in this specific case, geopolymerization effectively reduces the impact on climate change by 66% when sediment beneficial recovery was taken into account. This article is a first step in the industrial development adoption of waste geopolymer based mortar for public works as several conclusions were found to justify their implementation on a larger scale. Among them the use of alternative local precursors is effective in order to reduce the environmental cost of geopolymer. However, the market potential of geopolymer mortars will also highly depend on alternatives to silicate as an alkaline reagent.

The Impact of COVID-19 Pandemic on Hospital Waste Management: A Bibliometric Analysis

Any used solid, liquid, or gaseous substance will be immediately discarded. Dumped substance waste is generated in various places, including hospitals. The recent problem faced by hospitals is the outbreak of the COVID-19, a novel form of severe acute respiratory syndrome (SARS) that has resulted in a marked escalation in the generation of medical waste. The hospital management system covers hospital waste management. This management allows the hospital to monitor the amount and types of produced waste, thereby minimizing the harmful effects of waste. However, in this area, systematic analytical mapping studies still have numerous research limitations. This study aimed to provide a detailed analysis of the generated additional COVID-19 hospital waste and its impact on the environment and public health. Accordingly, this study applied the qualitative method with a literature study approach. The hospital waste management articles identified from 2020-2022 amounted to 920 publication articles indexed by Scopus, indicating that hospital waste management studies have increased in recent years. The study revealed that the COVID-19 pandemic caused an alarming surge in medical waste, posing a significant threat to the environment. This situation provides an opportunity to enhance healthcare waste (HCW) management systems in a manner that is both ecologically sound and secure.

Chitosan and Cyclodextrins-Versatile Materials Used to Create Drug Delivery Systems for Gastrointestinal Cancers.

Gastrointestinal cancers are characterized by a frequent incidence, a high number of associated deaths, and a tremendous burden on the medical system and patients worldwide. As conventional chemotherapeutic drugs face numerous limitations, researchers started to investigate better alternatives for extending drug efficacy and limiting adverse effects. A remarkably increasing interest has been addressed to chitosan and cyclodextrins, two highly versatile natural carbohydrate materials endowed with unique physicochemical properties. In this respect, numerous studies reported on fabricating various chitosan and cyclodextrin-based formulations that enabled prolonged circulation times, improved cellular internalization of carried drugs, preferential uptake by the targeted cells, reduced side effects, enhanced apoptosis rates, and increased tumor suppression rates. Therefore, this paper aims to briefly present the advantageous properties of these oligo- and polysaccharides for designing drug delivery systems, further focusing the discussion on nanocarrier systems based on chitosan/cyclodextrins for treating different gastrointestinal cancers. Specifically, there are reviewed studies describing promising solutions for colorectal, liver, gastric, pancreatic, and other types of cancers of the digestive system towards creating an updated framework of what concerns anticancer chitosan/cyclodextrin-based drug delivery systems.

Blockchain-Empowered Decentralized Philanthropic Charity for Social Good

The charity sector impacts society significantly in many areas, including providing education, healthcare, hunger relief, drinking water, disaster relief, environmental preservation, and assistance to underserved people. The existing charity organizations have numerous limitations, such as poor management, high operation costs, and a lack of transparency in the donation execution flow. The authentication of users and institutions is a big problem in the existing system. This research resolves the issues of transparency and reliability with an immutable and traceable distributed ledger. We empower the existing centralized charity works with the electronic know-your-customer (eKYC) authentication approach and cryptographic HASH. Information privacy is implemented using the filters within smart contracts. The implementation of eKYC to ensure authenticity and to secure data flow through the channel are two significant contributions of this work. A coin-toss function for data selection and a random time delay between pieces of data are used to avoid attacks based on guesswork. We aim for this framework to send 100% of donations to the beneficiaries and become a hyper-liquid medium to fill the United Nations Sustainable Development Goals (SDG) funding gap. We also introduce the concept of service charity to broaden the ability for people to offer their services and skills as charity.

Construction Schedule versus Various Constraints and Risks

The organization and planning of construction works are difficult issues due to the complexity, numerous limitations, uncertainty and risks associated with them. Construction planning is usually based on deterministic data. However, numerous studies and analyses of real cases show that a different computational approach is needed—one based on probabilistic data. The computational algorithms of the Time Coupling Method make it possible to introduce probabilistic data generated in the Multivariate Method of Statistical Models (MMSM) and via standard deviations. As a result, a new methodology was created, the Probabilistic Time Coupling Method (PTCM), through which it is possible to obtain a very good forecast of the investment implementation time compared to its real time. The paper presents theoretical considerations, computational schemes and validation exercises of this new method—known as the PTCM. The computational results of the PTCM (with a mapping accuracy prediction of 99%) confirm the effectiveness of the method. The computational algorithms of the PTCM enable the creation of a computational application based on a well-known program, e.g., Microsoft Excel, thanks to which the method can be quickly disseminated in the planning environment and widely used.

Yield criterion for intergranular void coalescence under combined tension and shear

Intergranular ductile fracture is a failure mode that may arise in many metallic alloys used in industrial applications. It manifests as the successive nucleation, growth, and coalescence of cavities at grain boundaries. Thus, simulation of intergranular ductile fracture in polycrystals requires modeling those three different stages at the scale of grain boundaries, i.e. at the interface between two different crystals. In this study, a yield criterion for the coalescence of cavities at the interface between two isotropic materials obeying Mises plasticity is first developed by limit analysis in order to provide some insights into that phenomenon. This criterion is checked against numerical limit analysis under combined tension and shear and is found to agree with unit-cell simulations quantitatively. The model is then extended to crystals so as to account for the complex coupling between loading state, crystallographic orientations, and void microstructure in intergranular coalescence. This second criterion is also assessed through comparisons to numerical limit analysis for an FCC crystal lattice. The agreement is very good in the case of coalescence by internal necking and the trends displayed by coalescence under combined tension and shear are captured correctly. Some implications of the model on the competition between transgranular and intergranular ductile fracture are discussed. Finally, by combining this model with an existing criterion for void growth at grain boundaries, a multi-surface yield function relevant to intergranular ductile fracture is obtained and compared to unit-cell simulations.

Attribution of neuropsychiatric symptoms and prioritisation of evidence in the diagnosis of neuropsychiatric lupus: mixed methods analysis of patient and clinician perspectives from the international INSPIRE study.

Neuropsychiatric lupus (NPSLE) is challenging to diagnose. Many neuropsychiatric symptoms, such as headache and hallucinations, cannot be verified by tests or clinician assessment. We investigated prioritisations of methods for diagnosing NPSLE and attributional views. Thematic and comparative analyses were used to investigate how clinicians prioritise sources of evidence from a 13-item list, and explore discordances in clinician and patient perspectives on attribution. We identified high levels of variability and uncertainty in clinicians' assessments of neuropsychiatric symptoms in SLE patients. In attributional decisions, clinicians (surveys n = 400, interviews n = 50) ranked clinicians' assessments above diagnostic tests (many of which they reported were often unenlightening in NPSLE). Clinicians ranked patient opinion of disease activity last, and 46% of patients reported never/rarely having been asked if their SLE was flaring, despite experienced patients often having "attributional insight". SLE Patients (surveys n = 676, interviews n = 27) estimated higher attributability of neuropsychiatric symptoms to the direct effects of SLE on the nervous system than clinicians (p < 0.001 for all symptoms excluding mania), and 24% reported that their self-assessment of disease activity was never/rarely concordant with their clinicians. Reports of misattributions were common, particularly of non-verifiable diffuse symptoms. Terminology differed between clinicians and influenced attribution estimates. NPSLE diagnostic tests and clinician assessments have numerous limitations, particularly in detecting diffuse neuropsychiatric symptoms that can be directly attributable and benefit from immunosuppression. Our findings suggest that incorporating patient attributional insights-although also subject to limitations-may improve attribution decision-making. Consensus regarding terminology and interpretations of "direct attributability" is required.

Production and utilization of green ammonia for decarbonizing the energy sector with a discrete focus on Sustainable Development Goals and environmental impact and technical hurdles

Green ammonia produced from renewable sources with little to no carbon emissions is considered as a carbon-free energy. Specifically, ammonia is an attractive energy carrier because of its high energy density, comparatively low-cost, and ease of liquefaction and storage. Ammonia generated worldwide is being used majorly as fertilizer however, in recent days, it has drawn more interest as a potential energy source and direct fuel in three key sectors namely electricity, transport, and heating. However, using green ammonia in diverse sectors has numerous challenges and limitations. Thus, this review aims to address the significance and application of green ammonia in the hydrogen energy sector and techno hurdles and environmental impact assessment of green ammonia utilization. At the outset, the importance of green ammonia and its utilization as a hydrogen energy carrier, the Power-to-ammonia-to-power (P2A2P) system, and the role of green ammonia in the Sustainable Development Goals were critically discussed. In the succeeding chapter, green ammonia's technological obstacles and its environmental impact were extensively articulated with state-of-the-art articles to lay a roadmap for decarbonizing the environment/energy sector by successfully utilizing ammonia as a hydrogen energy carrier/carbon-free green energy.

Insight on Gaussian Basis Set Truncation Errors in Weak to Intermediate Magnetic Fields with an Approximate Hamiltonian.

Strong magnetic fields such as those found on white dwarfs have significant effects on the electronic structures of atoms and molecules. However, the vast majority of molecular studies in the literature in such fields are carried out with Gaussian basis sets designed for zero field, leading to large basis set truncation errors [Lehtola et al., Mol. Phys. 2020, 118, e1597989]. In this work, we aim to identify the failures of the Gaussian basis sets in atomic calculations to guide the design of new basis sets for strong magnetic fields. We achieve this by performing fully numerical electronic structure calculations at the complete basis set (CBS) limit for the ground state and low lying excited states of the atoms 1 ≤ Z ≤ 18 in weak to intermediate magnetic fields. We also carry out finite-field calculations for a variety of Gaussian basis sets, introducing a real-orbital approximation for the magnetic-field Hamiltonian. Our primary focus is on the aug-cc-pVTZ basis set, which has been used in many works in the literature. A study of the differences in total energies of the fully numerical CBS limit calculations and the approximate Gaussian basis calculations is carried out to provide insight into basis set truncation errors. Examining a variety of states over the range of magnetic field strengths from B = 0 to B = 0.6B0, we observe significant differences for the aug-cc-pVTZ basis set, while much smaller errors are afforded by the benchmark-quality AHGBSP3-9 basis set [Lehtola, J. Chem. Phys. 2020, 152, 134108]. This suggests that there is considerable room to improve Gaussian basis sets for calculations at finite magnetic fields.

Disaster Risk Assessment for Railways: Challenges and a Sustainable Promising Solution Based on BIM+GIS

Natural hazards constantly threaten the sustainable construction and operation of railway engineering facilities, making railway disaster risk assessment an essential approach to disaster prevention. Despite numerous studies that have focused on railway risk assessment, few have quantified specific damages, such as economic losses and human casualties. Meanwhile, the mechanism of impact damage from various disasters on railway facilities and the propagation of functional failure in railway systems have not been thoroughly summarized and addressed. Thus, it is essential to conduct effective quantitative risk assessments (QRAs) to facilitate the sustainable design, construction, and operation of rail infrastructure. This paper aimed to review and discuss the systematic development of risk assessment in railway engineering facilities. Firstly, we highlighted the importance of disaster QRA for railway facilities. Next, numerous limitations of QRA methods were concluded after conducting a comprehensive review of the risk assessment research applied to railway facilities, such as bridges, tunnels, and roadbeds. Furthermore, true QRA (TQRA) application in railway engineering has faced several significant challenges. Therefore, we proposed a promising TQRA strategy for railway engineering facilities based on the integration of building information modeling (BIM) and geographic information systems (GIS). The proposed BIM+GIS technology is expected to provide sustainable future directions for railway engineering QRA procedures.

THE EFFECT OF DIFFERENT DESIGN RATIOS ON THE COMPRESSIVE STRENGTH OF GEOPOLYMER CONCRETE: A PARAMETRIC STUDY USING THE TAGUCHI METHOD

This paper presents the influence of numerous limits on compressive strength of fly ash-based geopolymer concrete mixtures optimized by Taguchi method using Minitab program. The major goal is to find the optimal ratios that may give the greatest compressive strength of geopolymer concrete. A total of twenty fife mixtures of geopolymer concrete with fife mixtures of normal concrete were assessed considering the effect of inclusion of Alkali-Activator to binder ratio (AA/B), NaOH concentration (M), Influence of Na2SiO3 to NaOH ratio (SS/SH) and effect of binder content (B). Different molarities was used in this study: 8, 10, 12, 14, and 16. Flay ash by way of waste material is used in ratios of (15, 17.5, 20, 22.5, and 25) % and substituted via 90 % of ordinary Portland cement to output the geopolymer concrete. Also, sodium silicate to sodium hydroxide are utilized in ratios of 1, 1.5, 2, 2.5, and 3. The alkali activator was made using sodium silicate, sodium hydroxide, and water in ratios of (0.3, 0.35, 0.4, 0.45, and 0.5). One type of locally crushed coarse aggregate was used instead of normal coarse aggregate that has sizes of 19 mm, as well as, fine aggregate. The examined mechanical property is characterized by compressive strength. The outcomes specify that the geopolymer concrete exhibits The highest compressive strength has been reached when the alkali-activator to binder ratio equal to 0.45, NaOH concentrations equal to 16, Na2SiO3 to NaOH ratio equal to 1 and binder content reached to 25 %. Also, the result showed that the compressive increases as the curing age increases. Moreover, scanning electron microscopy was evaluated to show the geopolymer concrete microstructure.

A numerical study on the visco-plastic regularization of a rate-independent strain gradient crystal plasticity formulation

A common practice in computational investigations of rate-independent plasticity is to approximate the rate-independent behavior by a visco-plastic regularization. As the fidelity of the approximation increases, the numerical solution of the non-linear problem becomes challenging and it can eventually lead to divergence; thus, there is a numerical limit to the regularization parameter. This limit may be exacerbated by complex material models and critical values of material parameters. Due to these constraints, the regularization may be rendered insufficient and the artificially introduced rate-dependency may lead to a behavior that can be mistakenly attributed to the material model and that we thus identify as spurious in a rate-independent context. To study these spurious effects and their onset, here the problem of an infinite strip under shear loading is numerically solved using a visco-plastic regularized gradient crystal plasticity formulation. The required accuracy of the rate-dependent approximation is found to vary with respect to the type of loading. Furthermore, a set of sigmoid functions used for the regularization is investigated and a subset is shown to deliver improved approximation of the rate-independent case.

The evaluation of translated neuropsychological assessments tools for the early detection of mild cognitive impairment (MCI) in low‐ and middle‐income countries (LMICs)

AbstractBackgroundThe incidence of mild cognitive impairment (MCI), particularly in low and middle‐income countries (LMICs) has been noticeably on the rise. With the high cost of dementia care, the need for tools that aid with the early detection of MCI is becoming of high importance, especially in LMICs. As a part of screening for MCI, many tests have been proposed evaluating for impairments in cognitive, behavioral, and functional domains, which are important for ruling out and evaluating for any reversible causes. While useful, most of these tests were developed in the west, limited works exist reporting the appropriateness and experience of using such tests for patients from LMICs.MethodIn this work, we aim to evaluate the use of translated digital assessment for detecting MCI in an Arabic‐speaking population in Palestine. For this purpose, we developed a digital test covering three cognitive, behavioral, and functional domains, where MMSE and the Neuropsychiatric Inventory ‐ Questionnaire (NPI‐Q) together with two functional assessment questionnaires were translated to Modern Standard Arabic (MSA) and presented in a digital interface. Upon the development and translation of the digital tests, field testing was conducted to check for use experience and appropriate patient comprehension of the questions to match their intended use.ResultFollowing the implementation of the digital assessment tools, quantitative and qualitative data was collected summarizing the user experience, where numerous limitations were noted. Despite being asked in their native language, several patients expressed the need for more clarifying questions. While all patients were Arabic speakers, some patients required the use of simpler terminology that matches their local dialects. Other patients reported the lack of relevance of certain questions, regarding the activities of daily living in the functional assessments. Overall, the patient’s experience and comprehension of questions varied with their age and literacy level.ConclusionDespite the high prevalence of dementia in LMICs, there are limited available neuropsychological assessment tools that are fit for the local cultural and linguistic. The findings suggest the need for the development of culturally and linguistically appropriate assessments to ensure appropriate patient comprehension, and avoid misdiagnosis of patients.

Human liver organoid models for assessment of drug toxicity at the preclinical stage.

The hepatotoxicity of drugs is one of the leading causes of drug withdrawal from the pharmaceutical market and high drug attrition rates. Currently, the commonly used hepatocyte models include conventional hepatic cell lines and animal models, which cannot mimic human drug-induced liver injury (DILI) due to poorly defined dose-response relationships and/or lack of human-specific mechanisms of toxicity. In comparison to 2D culture systems from different cell sources such as primary human hepatocytes and hepatomas,, 3D organoids derived from an inducible pluripotent stem cell (iPSC) or adult stem cells are promising accurate models to mimic organ behavior with a higher level of complexity and functionality owing to their ability to self-renewal. Meanwhile, the heterogeneous cell composition of the organoids enables metabolic and functional zonation of hepatic lobule important in drug detoxification and has the ability to mimic idiosyncratic DILI as well. Organoids having higher drug-metabolizing enzyme capacities can culture long-term and be combined with microfluidic-based technologies such as organ-on-chips for a more precise representation of human susceptibility to drug response in a high-throughput manner. However, there are numerous limitations to be considered about this technology, such as enough maturation, differences between protocols and high cost. Herein, we first reviewed the current preclinical DILI assessment tools and looked at the organoid technology with respect to in vitro detoxification capacities. Then we discussed the clinically applicable DILI assessment markers and the importance of liver zonation in the next generation organoid-based DILI models.

Dual delivery systems combining nanocrystals and dissolving microneedles for improved local vaginal delivery of fluconazole.

Fluconazole (FLZ) has been widely used in the treatment of infection caused by Candida albicans, including the treatment of vulvovaginal candidiasis (VVC). However, when delivered orally, FLZ faces numerous limitations due to its poor solubility and undergoes the symptoms of first-pass metabolism. In this study, we developed the combinatorial approach of nanocrystals (NCs) and dissolving microneedles (DMNs) for effective local vaginal delivery of FLZ. The formulation containing 1.0% w/v PVA as stabilizer with 12h of milling time process was found to be an optimal combination to fabricate FLZ as NCs (FLZ-NCs) with optimum size particle and PDI value (less than 0.25). Furthermore, the in vitro release study also showed a superior percentage of FLZ release up to 89.51 ± 7.52%. In combination with the DMNs, the FLZ recovery was 96.45 ± 2.38% with the insertion percentage in average of 76.14 ± 2.28% and height decreased percentage was only 7.53 ± 0.56%. Moreover, the ex vivo investigation and anti-candidiasis activity of DMNs-FLZ-NCs in vaginal model showed better results compared to other conventional preparations, such as film patch and hydrogel containing FLZ.

Pyrolysis Kinetics Analysis and Prediction for Carbon Fiber-Reinforced Epoxy Composites.

Carbon fiber-reinforced epoxy resin composites have poor high temperature resistance and are prone to thermal damage during service in the aerospace field. The purpose of this study was to evaluate the thermal decomposition (pyrolysis) characteristics of carbon fiber-reinforced epoxy composites and reasonably predict their thermal decomposition under arbitrary temperature conditions. The kinetic analysis was conducted on the thermal decomposition of carbon fiber-reinforced epoxy resin composites (USN15000/9A16/RC33, supplied by Weihai GuangWei Composites Co., Ltd. Weihai City, Shandong Province, China) under a nitrogen environment, and an improved model of pyrolysis prediction suitable for the arbitrary temperature program was developed in this work. The results showed that the carbon fiber-reinforced epoxy composites begin to degrade at about 500 K, and the peak value of the weight loss rate at the respective heating rate appears in the range of 650 K to 750 K. A single-step reaction can characterize the thermal decomposition of carbon fiber-reinforced epoxy composites in a nitrogen atmosphere, and a wide variety of isoconversional approaches can be used for the calculation of the kinetic parameters. The proposed model of pyrolysis prediction can avoid numerous limitations of temperature integration, and it shows good prediction accuracy by reducing the temperature rise between sampling points. This study provides a reference for the kinetic analysis and pyrolysis prediction of carbon fiber-reinforced epoxy composites.

Determination of a Numerical Surge Limit by Means of an Enhanced Greitzer Compressor Model

The surge limit of centrifugal compressors is a key parameter in the design process of modern turbochargers. Numerical methods like steady-state simulations are state-of-the-art methods for predicting the performance of the centrifugal compressor. In contrast to that, the determination of the surge limit with any numerical method is still an unsolved challenge. Since the extensive work of Greitzer and many other researchers in this field, it is well-known that surge is a system-dependent phenomenon. In the case of steady-state simulations, the simulation domain is chosen to be as small as possible due to the numerical cost. This simply implies that there is no system information included in the numerical model. Therefore, it is not possible to determine any system-dependent surge limit with today’s applied numerical methods. To overcome this issue, an enhanced Greitzer surge model, which has been developed at Tu Darmstadt, should act as a link between the simulation and the system in which the compressor will be operated. The focus of this paper will rather be on the methodology of determining the surge limit by means of numerical data than on the surge model itself. The methodology will be validated by experimental data of different systems.