Global Performance Analysis Research Articles

Impact of hull flexibility on the global performance of a 15 MW concrete-spar floating offshore wind turbine

In this study, we investigated the impact of the hull flexibility of 15MW spar-type FOWT (floating offshore wind turbine) on the global dynamics/performance analysis. Until recently, the rigid hull (floating foundation) model with flexible tower and RNA (rotor-nacelle assembly) has been used as industry standard procedure in the global performance analysis of FOWTs. Since the FOWT size continues to increase beyond 20MW, there has been increasing concern of the effect of hull flexibility on its global performance. The present study is intended to provide representative insights on this subject. Global performance analysis of the 15MW WindCrete spar is examined based on the conventional hull-rigid and the DMB (discrete-module-beam) models including hull flexibility. Coupled aero-hydro-servo-elastic-mooring dynamic simulations were carried out with the rigid-hull and DMB (discrete-module-beam) models under various combinations of irregular waves, sheared currents, and full-field turbulent winds. The lowest fore-aft bending-mode natural frequency is shifted toward lower frequency from 0.52 to 0.41 Hz after including hull flexibility. Platform rigid 6-DOF (degree-of-freedom) motions and mooring tensions by the DMB model are little changed but nacelle horizontal accelerations and tower-base bending moments may be appreciably increased compared to the rigid-hull model.

Bibliometric analysis of global performance and trends of research on combined sewer overflows (CSOs) from 1990 to 2022.

Combined sewer overflows (CSOs) are one of the main sources of pollution in urban water systems and significantly impede the restoration of water body functionalities within urban rivers and lakes. To understand the research and frontier trends of CSOs comprehensively and systematically, a visual statistical analysis of the literature related to CSOs in the Web of Science core database from 1990 to 2022 was conducted using the bibliometric method using HistCite Pro and VOSviewer. The results reveal a total of 1,209 pertinent publications related to CSOs from 1990 to 2022, and the quantity of CSOs-related publications indicated an increasing trend. Investigations of the distribution and fate of typical pollutants in CSOs and their ecological effects on receiving waters and studies on pollution control technologies (source reduction, process control, and end-of-pipe treatment) are the current focus of CSOs research. CSOs pollution control technologies based on source reduction and the monitoring and control of emerging contaminants are at the forefront of scientific investigations on CSOs. This study systematically and comprehensively summarized current research topics and future research directions of CSOs, thus providing a reference for CSOs control and water environment management research.

The Impact of Various Heating Rates on Real-Time Degree of Hybrid Fire Simulation

Global fire performance of structures in fire is proven to be more advantageous in many cases of engineering practice than the prescriptive fire resistance based on isolated structural member testing. Hybrid fire simulation (HFS) is a novel well-suited method trending in recent years for analysis of global performance of structures in fire. In the principles of this method, the part of a structure which has unknown behavior or is uncertain to be numerically modeled (subjected to fire) would be physically tested, while the rest of the structure is numerically simulated. HFS method enables capturing the beneficial interaction mechanisms evolving between fire-exposed structural members and the adjacent cooler substructure. Due to the continuous temperature increase in a fire test and the existing thermal inertia as well as the rate- and temperature-dependent material behavior of structures exposed to fire, a real-time performance in hybrid fire simulation counts as a necessity. This challenge is more critical for hybrid fire simulations with higher applied heating rates relevant to structural fire engineering. Within scope of this paper, (a) a robust and rigorous approach for real-time HFS is presented; (b) a series of proof-of-concept studies of different hybrid fire simulations with various applied heating rates are carried out for a thermomechanical benchmark problem; (c) the important results of four representative hybrid fire simulations with relevant heating rates to structural fire engineering are discussed; (d) the importance of an appropriate calculation method for stiffness update of the fire-exposed structural member over HFS procedure is highlighted, and e) the precision and accuracy of the applied HFS approach with respect to interface error and real-time degree are evidenced.

Offshore Fish Farms: A Review of Standards and Guidelines for Design and Analysis

While moving fish farms to offshore sites can be a more sustainable way to expand farmed fish production, the fish pens have to contend with a harsher environment. Thus, it is necessary to draw on offshore engineering competences for designing and analysing the offshore fish farming infrastructure. This paper reviews existing design and analysis guidance from maritime classification and national/international authorities that can be applicable for offshore fish farms. Based on the existing design guidelines, a review of design criteria for offshore fish farms under the following subtopics is provided: design life, design environmental loads, combining environmental loads, and miscellaneous load conditions. This review on the global performance analysis procedures and methods is presented based on practices used for neighbouring industries, such as offshore oil and gas and wind energy production, under the following subtopics: hydrostatic analysis, hydrodynamic analysis, and mooring system analysis with introducing theoretical background and modelling techniques. This paper also highlights limitations and cautions when using these design and analysis methods. Providing this comprehensive information, as well as commentary on their applications, will help engineers and designers to develop offshore fish farming infrastructure with confidence.

Global performance analysis of a solar-driven indoor CO2/H2O capture system for air quality enhancement and cooling energy saving

A human-eco-friendly building requires high indoor air quality (IAQ) and low carbon emissions. Existing natural/mechanical ventilation methods rely on frequent exchange with fresh ambient air to remove excess respiratory CO2 for high IAQ. However, in tropical or subtropical regions, the introduced ambient air features higher humidity and temperature over indoor air, which inevitably increases the energy burden of air conditioning (AC) accompanied with severe CO2 emission. To circumvent this paradox, this study developed a dynamic solar-driven indoor CO2/H2O capture system with selective air recirculation. Rather than simply introducing ambient air to reduce indoor CO2 concentration, this scheme actively captures CO2/H2O and selectively returns post-captured air with sub-ambient temperature, relative humidity and CO2 concentration, thus sustaining high IAQ with reduced AC load and CO2 emission. The system’s feasibility and stability are demonstrated through a 20-city global study and a 10-variable sensitivity analysis. Compared to traditional methods, this new system could save up to 64 % of cooling energy while maintaining the indoor CO2 concentration below 1000 ppm and relative humidity within 25 %-55 %. The energy-saving potential of the proposed system increases in regions with larger AC demands, as evidenced by Dakar achieving the highest energy-saving potential and thus decreasing CO2 emission. This system could further reduce CO2 emission by direct capture and storage, whose amount is positively correlated to the amount of solar irradiance in cities. Furthermore, the system demonstrates robustness under off-design conditions and is flexible to be scaled up/down. Overall, this study provides effective-green ventilation strategies and paves the way for developing human-eco-friendly buildings.

INS-Aided Multi-Antenna GNSS Carrier Phase Double Difference Spoofing Detection

The effective spoofing detection can prevent GNSS receiver from providing erroneous positioning, velocity and timing information. Most of the available multi-antennas carrier phase double difference-based spoofing detection methods, regardless of the aiding of inertial navigation system (INS), exploit the divergence in carrier phase double differences derived from the direction of arrival (DOA) characteristics of the authentic signal and spoofing signal. However, the traditional methods mainly implemented by dual-antenna GNSS receivers has spatial ambiguity and lacks global detection performance analysis. Furthermore, an INS-aided multi-antenna spoofing detection method is proposed without spatial ambiguity comparing the predicted signal DOA by INS and the vectoral carrier phase double differences measured by multi antennas. To analyze the influence of the antenna array baseline length and signal DOA on the detection performance, a comprehensive numerical simulation was conducted. The dead zone of the proposed detection method is revealed to assess the global spoofing detection performance. The effectiveness of the proposed method is verified under the GNSS positioning scenarios. In the worst case, spoofing signals can be effectively detected in 95.2% of the airspace under one time the wavelength antenna baseline configuration and in 99.3% of the airspace under five times the wavelength antenna baseline configuration, respectively.

Analysis of FPSO station keeping characteristics

Nowadays with increasing production and exploration activities offshore, the FPSO system has been widely adopted globally because of its unique design system and adaptability to these offshore environmental conditions. This research project aims to provide the station-keeping characteristics of an FPSO in the West African region, by analysing an FPSO with spread mooring design for multiple load cases, different offset, multiple draught conditions and environmental loads, all acting simultaneously and dynamically on the coupled FPSO system. Static and dynamic analysis were conducted using the Orcaflex software to establish the station-keeping characteristics, the recommended practices by DNV for mooring and global performance analysis were utilized for the mooring lines in the static analysis to obtain the primary equilibrium position before the dynamic analysis was conducted and to estimate a dynamic response of the risers in dynamic analysis. The effective tension of the static and dynamic analysis results for the different draught and environmental conditions shows that the far offset had the maximum effective tension, with the fully laden effective tension been the maximum effective tension of the entire simulation. The increase in effective tension as the loading of the FPSO tanks increased caused a reduction in the bending moment radius and thereby reducing the curvature of mooring lines and riser bends. But it was the near offsets that had the minimum bending radii as expected, however, from the analysis the draught conditions provided the largest responses to the multiple loading cases when compared with the changes in the offset positions.

Time-dependent performance of large-scale dome structures subjected to earthquakes using a machine learning-based evaluation method

The global time-dependent performance analysis of structural systems has aroused the interest of researchers in recent years. The conventional technique using finite element analysis is very computationally intensive in evaluating the time-dependent performance of structures with multiple variables. A new hybrid method by integrating a surrogate model with the subset simulation is proposed to evaluate the time-dependent performance of large-scale complex structures subjected to earthquakes. The surrogate model is constructed based on the multilayer perceptron network using a small dataset and the subset simulation is used to estimate the small failure probability. Large-scale dome structures under earthquakes are used to verify the proposed method. The results show that surrogate models have a high accuracy in estimating extreme structural deformations when compared to the high-fidelity results using the finite element method. The hybrid method is efficient and accurate for the global time-dependent reliability analysis. The global sensitivity analysis for the dome structures is also conducted and the importance of variables over the life cycle is evaluated using the surrogate models. The numerical examples demonstrate that the method is highly efficient and accurate in quantifying uncertainty in the time-dependent performance of large-scale complex structures.

A bibliometric analysis of global research performance on tuberculosis (2011-2020): Time for a global approach to support high-burden countries.

BACKGROUND:Tuberculosis (TB) is a persistent public health issue requiring consistent global effort for its eradication and control. Research on the subject plays a vital role in combatting the disease, giving future directions, and meeting the sustainable development goals (SDGs). This study aimed to evaluate the global TB research trends and performance from 2011 to 2020.MATERIALS AND METHODS:All the data for TB-related research publications from 2011 to 2020 were extracted from the Web of Science database and a comprehensive analysis was performed on the R-bibliometrix package.RESULTS:An increasing number of publications with an annual growth rate of 6.32% and a plateau in production from 2015 to 2018 was observed. Of 145 countries, the United States of America (USA), China, India, the United Kingdom, and South Africa led and made up half of the global contribution. Out of 91,862 authors, Zhang Y was the most productive with 205 articles and Barry CE had the highest H-index of 45. Only seven of the top 20 authors were from high-burden countries. The University of Cape Town was the leading institutional affiliation, followed by Stellenbosch University and the London School of Hygiene and Tropical Medicine. The most frequent international collaboration was between the USA and South Africa, occurring on 1203 instances. Only five of the top 30 high-burden countries were present in the top 30 collaborations. PLOS ONE, disseminating 2271 articles, was the most productive out of 3500 sources.CONCLUSION:The past decade has seen a steady increase in global TB research. Prominent authors, affiliations, and countries showed collaborative trends, but publications were found to be mostly from developed, low-burden countries except China, India, and South Africa. To meet the goals set by the SDGs and the WHO End TB Strategy, high-burden countries need to explore feasible opportunities and global support to enhance their expected TB-related research contributions.

The Impact of Technological Development on Managerial Resilience in the Military Organisation

The current course of the 21st century has challenged humanity as a whole in terms of the operationalisation of large-scale changes, both quantitative and qualitative, one of the directions for changing social functionality being subsumed under global technological governance. Trends specific to emerging and disruptive technologies, technological superiority, digital diplomacy and sovereignty, innovation ecosystems etc. have a major impact on a macro-indicator of analysis of contemporary global performance, namely resilience. The pace of implementing the solutions characteristic to these advanced technologies is a dynamic one, practically influencing all areas of activity. At the military level, there are concerns of interest at the level of NATO member states regarding space systems, robotics and advanced conventional weapons systems (laser, hypersonic weapons), innovative resources, digitisation, artificial intelligence, cyber security etc. In this context, the present article brings to attention some presumptive aspects regarding the modification of managerial resilience, in terms of military roles and responsibilities, starting from classical managerial theories. Directions for exploring the subject proposed by the title which are of interest to military decision-makers are also presented.

Impactul dezvoltării tehnologice asupra rezilienței manageriale în organizația militară

The current course of the 21st century has challenged humanity as a whole in terms of the operationalisation of large-scale changes, both quantitative and qualitative, one of the directions for changing social functionality being subsumed under global technological governance. Trends specific to emerging and disruptive technologies, technological superiority, digital diplomacy and sovereignty, innovation ecosystems etc. have a major impact on a macro-indicator of analysis of contemporary global performance, namely resilience. The pace of implementing the solutions characteristic to these advanced technologies is a dynamic one, practically influencing all areas of activity. At the military level, there are concerns of interest at the level of NATO member states regarding space systems, robotics and advanced conventional weapons systems (laser, hypersonic weapons), innovative resources, digitisation, artificial intelligence, cyber security etc. In this context, the present article brings to attention some presumptive aspects regarding the modification of managerial resilience, in terms of military roles and responsibilities, starting from classical managerial theories. Directions for exploring the subject proposed by the title which are of interest to military decision-makers are also presented.

Modelling and simulation of DME navigation global service volume

• Availability area analysis of distance measuring equipment global network. • Service volume is estimated based on path loss model. • Distance measuring equipment. • DME service can be provided only in 27.76% of global airspace. Safety of air transportation strongly depends on the performance of on-board positioning sensors. Positioning by data from navigational aids is considered by international aviation community as one of the main stand-by positioning approaches onboard of civil airplanes. However, only positioning by pair of distance measuring equipment (DME) meets requirements of Performance-Based Navigation. A DME service volume model based on path loss between a pair of transmitting and receiving antennas has been proposed in the paper. The model takes into account the influence of relief on radio waves propagation and diffraction from high-altitude elements of relief. The proposed model has been used in the analysis of DME global network performance. In particular, performance of a global network is analyzed based on availability area of DME service, area of positioning by pairs of DME/DME support, availability of particular positioning accuracy, and areas of meeting various RNAV requirements. Obtained results indicate that only in 27.76% of global airspace a DME service can be provided. However, only within 15.9% of airspace, a DME/DME positioning can be used. Results of the analysis indicate about the necessity of actions for further development of global navigational aids network in order to guarantee safe airlines connections around the globe.

A NEW INDOOR LIDAR-BASED MMS CHALLENGING COMPLEX ARCHITECTURAL ENVIRONMENTS

Abstract. The use of moving devices equipped with range- and image-based sensor, generically defined Mobile Mapping systems (MMS), have been quite a disruptive innovation in the development of Geomatics techniques for 3D surveying large indoor-outdoor spaces and offer multiple solutions. The recent expansion of portable devices in the form of trolleys, backpacks, handheld tools largely implements SLAM (Simultaneous Localization and Mapping) algorithms and technology based on both Lidar and/or visual solutions for answering to the positioning and the 3D reconstruction problems. The research on MMS is directed to improve both multi-sensor integration implementation and usability of systems in diversified use contexts and application fields. The aim of the presented research is the evaluation of the potential of the Swift system recently developed by FARO Technologies, that has been fine-tuned for regular and large extent interiors mapping (such as factories, hospitals, airports, offices). The work tries to preliminary investigate the data delivery and usability of the integrated system. This is based on three elements mounted on a sliding trolley moved by the operator walking: the ScanPlan profilometer working for the 2D SLAM mapping, the static TLS Focus S-series, and the smartphone managing the sensors operation and the acquisition progress. The evaluation strategy undertaken will be based on the global and local performance analysis related to the trajectory, the data accuracy, the metric content and consistency. Two test studies belonging to the 20th century. architecture are presented in a preliminary framework of evaluation and validation: a Liberty-style cinema and the Torino Esposizioni Hall B designed in ferrocement by pier Luigi Nervi.

Distributed robust secondary voltage control for islanded microgrid with nonuniform time delays

This paper proposes a nonuniform delay-dependent robust secondary voltage control strategy with a finite-time voltage reference observer for an islanded microgrid. A discrete-time consensus algorithm is introduced to track the output voltage. By model transformation, a closed-loop microgrid control system is obtained. And then, the corresponding global stability and robust performance analysis theorems are derived. After implementing a series of trial studies, the impacts of secondary voltage control gains, sampling time on energy-to-peak robust performance are obtained. And the feasible optimal voltage control gains can be derived. Besides, a distributed cooperative secondary frequency control is introduced. Simulations of a four inverter-based microgrid test system are presented to verify the control performance. The simulation results indicate that our proposed method can maintain accurate voltage/frequency restoration and active power sharing. In addition, the voltage control gain parameters, arbitrary nonuniform time delays, and especially sampling time effects on the secondary voltage control performance are also verified.

Comparison of two polynomial approaches in performance analysis for periodic piecewise polynomial systems

In this paper, the theory and effectiveness of two polynomial approaches are compared in the analysis of L2-L∞ and H∞ performance for a type of periodic piecewise polynomial systems, where the time-varying subsystems can be characterized in Bernstein polynomials. Using the Bernstein polynomial-based lemma and the existing lemma concerning the negativity/positivity of matrix polynomial functions, sufficient conditions are established in tractable forms aimed at the global asymptotic stability and performance analysis. Four cases of optimization constraints are considered based on the proposed conditions. The performance indices obtained via the four cases are compared through a numerical example, and the lower conservatism achieved by the proposed Bernstein polynomial approach is demonstrated.

A global performance analysis methodology using Taguchi approach: case of cloud computing and supply chain

Nowadays, performance optimisation is identified as the major asset to maximise the quality-cost ratio of a given system. Particularly, the performance analysis of a complex system involving several processes and a multitude of stakeholders cannot be done without an efficient methodology. During this paper, we aim at the implementation of a generic methodology for performance analysis taking as a framework the case of cloud computing and supply chain. The proposed methodology is based on the fundamental idea of transforming a complex system into a black box which will be analysed through different inputs corresponding to the influential factors and outputs which translate the key performance indicators. The analysis of the interactions between influential factors and key performance indicators is carried out on the basis of the Taguchi concept. The conclusions of the proposed methodology make it possible to identify diverse perspectives in order to enhance the performance of the entire system.

Is the World Becoming a Better or a Worse Place? A Data-Driven Analysis

Is the World becoming a better or a worse place to live? In this paper, we propose a tool that can help to answer the question by combining a number of global indicators belonging to multiple categories. The proliferation of statistical data about various aspects of the World performance may suggest that it should be “easy” to evaluate the overall success of human enterprise on this planet. Moreover, it also points out the intrinsic importance in the selection of indicators. However, people have different values, biases, and preferences about the importance of various indicators, making it almost impossible to find an objective answer to this question. To address the variety and the heterogeneity of available indicators and world views, we present the analysis of global World performance as a multi-criteria decision problem, making sure that the assessment method remains as transparent as possible. By dynamically selecting a set of indicators of interest, defining the weights that we attach to various indicators and specifying the desired trends associated with each indicator, we make the assessment adaptive to individual values. We also try to deal with the inherent bias that may exist in the set of indicators that are chosen. As a study case, from various data sets that are openly available online, we have selected several that are most relevant and easy to interpret in the context of the question in the title of the paper. We demonstrate how the choice of personal preferences, or weights, can strongly change the result. Our method also provides analysis of the weights space, showing how results for particular value sets compare to the average and extreme (optimistic and pessimistic) combinations of weights that may be chosen by users.

Combined Solar Thermochemical Solid/Gas Energy Storage Process for Domestic Thermal Applications: Analysis of Global Performance

Thermal energy used below 100 °C for space heating/cooling and hot water preparation is responsible for a big amount of greenhouse gas emissions in the residential sector. The conjecture of thermal solar and thermochemical solid/gas energy storage processes renders the heat generation to become ecologically clean technology. However, until present, few pilot scale installations were developed and tested. The present work is devoted to the experimental study of global performance of a pilot scale thermochemical energy storage prototype. Two working modes, namely fixed packed bed and moving bed, were tested using 2.2 kg and 5.5 kg of composite material (silica gel impregnated with calcium chloride) under indoor atmospheric conditions. The global experimental efficiency of a 49l water tank charging process during 75 min was found as high as 0.8–0.85. The energy storage density reached in the fixed bed mode by the material was 158 kWh/m3, while in the moving bed mode it was 2.5 times lower. The reasons for such a difference are discussed in depth in the text.

계류선 배치에 따른 부유식 사장교의 정적 전체계 거동특성 분석

계류선 배치에 따른 부유식 사장교의 정적 전체계 거동특성 분석

SEISMIC VULNERABILITY ASSESSMENT OF A 17th CENTURY ADOBE CHURCH IN THE PERUVIAN ANDES

ABSTRACT A large part of Peruvian heritage corresponds to Colonial Andean churches, which are economically and culturally essential for the development of several villages. Particularly, adobe churches are very vulnerable to earthquakes due to the brittle material behavior, the weak connections, and the absence of a rigid diaphragm. This article aims at performing the seismic vulnerability assessment of an adobe heritage church: “Virgen de la Asuncion” of Sacsamarca located in the province of Ayacucho in the Andean region of Peru; using a rapid screening method and a more complex numerical analysis. First, the damage survey was carried out through visual inspection and infrared thermography, while the material characterization was performed by applying flat-jack tests. Later, the seismic vulnerability assessment was carried out in two stages. The first was based on simplified criteria for masonry structures, and the other on a pushover analysis of global performance. From this evaluation, it was possible to conclude that the church is indeed vulnerable to Peruvian seismic demands.