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The purpose of this paper is to validate mathematically the feasibility of extracting the rotating blades vibration condition from the shaft torsional vibration measurement.

A mathematical model is developed and simulated for extracting rotating blades vibration signatures from the shaft torsional vibration signals. The model simulates n‐blades attached to a rigid disk at setting angles and the shaft drives the disk is flexible in torsion. The model is developed using the multi‐body dynamics approach in conjunction with the Lagrangian dynamics. A three‐blade rotor system example is simulated for blades free and forced vibration under stationary and rotating conditions. Frequency spectrums for the shaft torsional and blades bending vibration are represented and studied for analysis verification purposes.

The torsional vibration frequency spectrums showed blades free and forced vibration signatures. The blade setting angle is shown to reduce the sensitivity of torsional vibration signal to blades vibration signatures as it increases. The torsional vibration signals captured the variation in blades properties and produced broadband frequency components for mistuned system. The shaft torsional rigidity is shown to reduce the sensitivity of torsional vibration signal to blades vibration if increased to extremely high values (approaching rigid shaft). The rotor inertia is shown to have less effect on the torsional vibration signals sensitivity. The method of torsional vibration as a tool for rotating blades vibration measurement, based on the proposed mathematical model and its simulation, is feasible.

There is a growing need for reliable predictive maintenance programs that in turn requires continuous development in methods for machinery health monitoring through vibration data collection and analysis. Turbo machinery and bladed assemblies like fans, marine propellers and wind turbine systems usually suffer from the problem of blades high vibration that is difficult to measure. The proposed new method for blades vibration measurement depends on the shaft torsional vibration signals and can be used also for verifying the signals from other types of bearings sensors for possible blades vibration condition monitoring.

This paper presents a unique mathematical model and simulation results for the rotating blades vibration monitoring. The developed model can be simulated for studying coupled blades vibration problems in the design stage as well as for condition monitoring in maintenance applications.

This paper presents experiment results that examine the validity of extracting blade vibration signature from the shaft torsional vibration signals. A special test rig was designed and manufactured for this objective. A set of strain gages were bonded to the shaft and to the blades to measure the shaft twisting and blade bending deformations respectively. A controlled frequency exciter excited the blade vibration. The shaft torsional and blade bending vibration signals were simultaneously recorded and presented in the time and frequency domains. The blade bending vibration frequencies appeared dominantly in the shaft torsional vibration signals for all blade vibration frequencies up to 100Hz. For frequencies higher than 100Hz, less sensitivity of the torsional vibration to blade vibration was observed.

Online spiral pipe manufacturing is one of the most common processes for producing water and gas transmission pipes. Weld quality and pipe circumstances are the most important qualitative characteristics of these pipes determining the overall cost of production. The purpose of this paper is describing how to implement Six Sigma on the production of spiral welded pipes with a real case study.

First, the capability of the pipe production process has been performed by using the defects per million opportunities to allow for comparison and analysis of the project effectiveness. Then, the variation pattern of this index, after an improvement project, has been investigated. Finally, Taguchi's loss functions are used to evaluate the effectiveness of these projects.

The results represent a significant improvement in the production process and a reduction in production costs regarding both weld quality and pipe circumstances. Due to the successful implementation of Six Sigma project in welding and pipe quality improvement, the Define, Measure, Analyze, Improve and Control (DMAIC) method can be used effectively in defining weld and pipe quality.

In this proposed work, for the first time, research on the implementation of Six Sigma in the pipeline and welding industries on two online spiral production machines has been investigated. The DMAIC method has been used for the first time to improve the dimensional quality and weld quality of spiral pipes.

Electricity demand forecasting has always been a key issue, and inaccurate forecasts may mislead policymakers. To accurately predict China’s electricity demand up to 2030, this paper aims to establish a cross-validation-based linear model selection system, which can consider many factors to avoid missing useful information and select the best model according to estimated out-of-sample forecast performances.

With the nine identified influencing factors of electricity demand, this system first determines the parameters in four alternative fitting procedures, where for each procedure a lot of cross-validation is performed and the most frequently selected value is determined. Then, through comparing the out-of-sample performances of the traditional multiple linear regression and the four selected alternative fitting procedures, the best model is selected in view of forecast accuracy and stability and used for forecasting under four scenarios. Besides the baseline scenario, this paper investigates lower and higher economic growth and higher consumption share.

The results show the following: China will consume 7,120.49 TWh, 9,080.38 TWh and 11,649.73 TWh of electricity in 2020, 2025 and 2030, respectively; there is hardly any possibility of decoupling between economic development level and electricity demand; and shifting China from an investment-driven economy to a consumption-driven economy is greatly beneficial to save electricity.

Following insights are obtained: reasonable infrastructure construction plans should be made for increasing electricity demand; increasing electricity demand further challenges China’s greenhouse gas reduction target; and the fact of increasing electricity demand should be taken into account for China’s prompting electrification policies.

Learning field of events is characterized by the occurrenceof random and uncertain phenomena, all of which have probabilistic distributions. The meaning of learning is exchange by interdependence between interacting agents. Such agents are both the human entities and the non‐human ones. Thus, in a learning field of probabilistic events there are complex forms of interaction between the domains of mind (human cognition) and matter (world‐system). The purpose of this paper is to formalize and study such interactions by the epistemology of unity of being and becoming of relations between given variables in analytical perspective.

The critical argumentation and search in this paper leads to the premise of the episteme of unity of knowledge. It is found singularly in the doctrine of the paired universe of the Quran. The episteme of oneness of the monotheistic law and its consequential forms establish the axiomatic basis of the criterion function representing the phenomenon of probabilistic learning field. The authors refer to this criterion as wellbeing. It conceptualizes and measures the degree of unity of being and becoming that exists between the variables of a specific problem under investigation.

The results of this study formalize the probabilistic model of learning. The simulated evaluation of the probabilistic form of the wellbeing function brings out the synonymous results between unity of knowledge and its impact on the unity of the world‐system induced by the knowledge‐flows. Such a transformation of a world‐system presents the meaning of endogenous (or systemically self‐regenerated) ethics and morality in such broader fields of choices involving embedded learning systems.

The dynamics of pervasive complementarities arising from learning by unity of knowledge, and considerations of ethics and morality remain exogenous factors in economic theory. This paper, instead, has formalized ethical endogeneity in models of decision‐making with probabilistic learning fields that remain embedded in complementarities by interaction and integration across economic, social and ethical systems.

The key purpose of conducting this review is to identify the issues that affect the structural integrity of pipeline structures. Heat affected zone (HAZ) has been identified as the weak zone in pipeline welds which is prone to have immature failures

In the present work, literature review is conducted on key issues related to the structural integrity of pipeline steel welds. Mechanical and microstructural transformations that take place during welding have been systematically reviewed in the present review paper.

Key findings of the present review underline the role of brittle microstructure phases, and hard secondary particles present in the matrix are responsible for intergranular and intragranular cracks.

The research limitations of the present review are new material characterization techniques that are not available in developing countries.

The practical limitations are new test methodologies and associated cost.

The fracture of pipelines significantly affects the surrounding ecology. The continuous spillage of oil pollutes the land and water of the surroundings.

The present review contains recent and past studies conducted on welded pipeline steel structures. The systematic analysis of studies conducted so far highlights various bottlenecks of the welding methods.

The purpose of this paper is to construct a series of narratives by assessing a selection of the key literature generated by Open House International (OHI) over a period of 15 years. The paper also presents a brief review of the latest developments of the journal while introducing concise observations on the articles published in this edition – Volume 45, Issues 1 and 2.

Through a classification procedure of selected special issues published by OHI since 2006, 10 issues were identified based on the currency of the issues they generated. Following the review of the editorials, the key content of more than 100 articles within these special issues, the content of this edition and relevant seminal literature, the analysis engages, through critical reflection, with various themes that echo the polyphonic nature of built environment research.

The analysis conveys the plurality and diversity in built environment research where generic types of narratives are established to include three categories, namely, leitmotif, contextual/conceptual and open-ended narratives. Each of which includes sub-narrative classifications. The leitmotif narrative includes design studio pedagogy, sustainable environments for tourism, responsive learning environments, affordable housing environments, diversity in urban environments and urbanism in globalised environments. The contextual/conceptual narrative encompasses architecture and urbanism in the global south and the tripartite urban performance and transformation. The open-ended narrative embraces thematic reflections on the contributions of this edition of OHI.

Constructing polyphonic narratives in built environment research based on contemporary knowledge is original in the sense of capturing the crux of the themes within these narratives and articulating this in a pithy form. The elocution of the narratives stimulates a sustained quest for re-thinking concepts, notions and issues of concerns while invigorating research prospects and setting the future direction of OHI.

The courtyard form of the traditional African house responds to people's culture and traditions. Nevertheless, in the era of globalization, the private open space (POS) is fast disappearing in African homes due to neglect and lack of awareness of its value. This study, thus, aims to explore how culture relates to open space design in traditional houses of three major ethnic groups (Hausa-Fulani, Yoruba and Igbo) in Nigeria. This is with a view to encouraging planners and designers to create open spaces in housing developments according to people's cultural values and needs.

This study is based on qualitative and quantitative research approaches involving a literature review, focus group discussions and a questionnaire survey. The quantitative survey was designed based on the literature review of the concept of culture and the use of space in traditional courtyard houses. Focus group discussions were conducted to identify the specific cultural components that dictated the use of the courtyard as a POS in the Nigerian context. Subsequently, a questionnaire survey was carried out to determine the importance of each cultural component in the outdoor sociospatial design. Through systematic sampling, one of every five traditional houses in the study area was selected to determine where respondents were surveyed.

The results reveal that the cultural components that influenced the design and use of the open space were gender and privacy, family and social relations, religious practice and belief, and status and lifestyle. However, the importance attached to each of the cultural components varied from one culture to another in Nigeria. The findings also showed that the open space is used for a variety of purposes, such as ancestral worship, family gatherings and reunions, small-scale ceremonies, and leisure activities.

This study offers professional planners and designers helpful insights to protect culture in housing development and improve daily living in residential environments.

Based on Amos Rapoport's theoretical framework, this study dismantles the concept of “culture” into different components and examines how they affect outdoor sociospatial design in a developing country. The study also provides researchers with ideas and inspiration to study the culture of POSs in traditional housing.

This study evaluates the aesthetic perception of photovoltaic (PV) systems situated at various locations on an apartment building facade, comparing them with the original facade. It also aims to understand how aesthetic dimensions influence the perception of PV installations in diverse building locations. Moreover, it aims to create a framework that will guide for installing PV installations considering both their functionality and aesthetics.

The study uses a mixed-method approach, including qualitative and quantitative approaches. It includes a literature review and a questionnaire. 418 participants evaluated different PV-embedded facades using a Likert scale across various aesthetic variables.

The findings indicate that aesthetic perceptions of PV vary by the location of installation. It also shows that all aesthetic dimensions affect PV installation aesthetics, with location-specific preferences. For original elevation, compatibility and simplicity are given precedence over blending and coherence for windows, creativity and harmony for facades, functionality and harmony for balconies, and innovation potential and simplicity for roofs.

This study focuses on a single building type; further investigation is required to examine other building types. It also examined one PV technology with common visual properties, but future studies can examine others. Additional research is needed to compare the participating groups and the effect of their sociodemographic factors, using on-site surveys and interviews.

Few studies have investigated how PV systems affect apartment building users' architectural aesthetic perception. The results of this study make a valuable contribution to the field of sustainable architecture by providing practical guidance for architects, engineers, stakeholders, and researchers who are interested in integrating aesthetic, user-centric considerations into renewable energy solutions.