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The purpose of this paper is to introduce a new concept in selecting the values of the DC source voltages in cascaded multi‐level inverters in order to improve the output voltage THD.

In cascaded multi‐level inverters, it is usually assumed that the DC sources have the same constant voltage and output harmonics minimization is accomplished by applying proper switching angles. Employing different DC voltages with proper ratios can result in further reduction of the harmonics. After formulation of the system, i.e. describing the inverter's output voltage components in terms of the switching angles and unequal DC source voltages, a rule is applied to obtain the step heights of the staircase output waveform (DC source voltages), so that the output waveform becomes as close to the required fundamental sine wave as possible. Substituting the obtained DC source voltages into the harmonics elimination equations results in a set of equations, which are functions of switching angles only. Solving these equations leads to proper switching angles, which, regardless of the fundamental component's value, provide the specified harmonic conditions. The output voltage is then controlled by DC sources voltage regulation.

Computer simulations show that employing the proposed concept results in substantial improvement in the harmonic minimization, as well as, extending the operating range of the inverter, compared to the conventional methods with equal DC source voltage multi‐level inverters.

The proposed concept according to which the ratio of the DC source voltages are determined, is original.

Multilevel inverters play a major role in the development of high-power industrial applications. In traditional low-level inverters (e.g. 2-level), the switching frequency is restricted and the harmonic spectrum of the system is hard to meet power requirements. Similarly, high-level inverters consist of a large number of switches, complex modulation techniques and complex hardware architecture, which results in high power loss and a significant amount of harmonic distortion. Furthermore, it is a must to ensure that every switch experiences the same stress of voltage and current. The purpose of this paper is to present an inverter topology with lower conduction and switching losses via reduced number of switches and equal voltage source-sharing technique.

Herein, the authors present a cascaded multilevel inverter having less power switches, a simple modulation technique and an equal voltage source-sharing phenomenon implementation.

The modulation technique becomes more complex when equal voltage source-sharing is to be implemented. In this study, a novel topology for the multilevel inverter with fewer switches, novel modulation technique, equal voltage source-sharing and Inductor-Capacitor-Inductor filter implementation is demonstrated to the reduce harmonic spectrum and power losses of the proposed system.

The nine-level inverter design is validated using software simulations and hardware prototype testing; the power losses of the proposed inverter design are elaborated and compared with the traditional approach.

The purpose of this paper is to propose a new converter topology for integrating PV plants constituted by many panels into the grid. The converter is capable of implementing MPPT algorithms on different subset of modules and can balance the different energy supplied by panels differently irradiated. The output voltage presents a very low ripple also if small filters are used for grid connection.

In the paper, at first the converter configuration is presented. Then a control strategy for obtaining, at the same time the distributed MPPT and the power balancing on the three phases is proposed. Finally, by means of numerical simulations, the good performances of the proposed converter are shown.

The proposed converter, lent from MMC configurations, is deeply studied and a suitable control strategy is well analyzed in the paper. Analytical model for voltage and current balancing are given.

The analysis presented in the paper complete some studies started in the last years and partially presented in previous scientific papers. It reaches a final point and gives all the specific for the realization of the converter and of its control.

The paper gives all the instrument to design and realize a PV power plant integrated into building façade.

The converter and the control for voltage and current balancing presented in this paper represent a significant original contribution of this work.

Several ultra-low power and gigahertz current-starved voltage-controlled oscillator (CSVCO) circuits have been proposed and compared here. The presented structures are based on the three-stage hybrid circuit of the carbon nanotube field-effect transistors (CNTFETs) and low-power MOSFETs. The topologies exploit modified and compensated Schmitt trigger comparator parts to demonstrate better consumption power and frequency characteristics. The basic idea in the presented topologies is to compensate the Schmitt trigger comparator part of the basic CSVCO for achieving faster carrier mobility of the holes, reducing transistor leakage current and eliminating dummy transistors.

This study aims to propose and compare three different comparator-based VCOs that have been implemented using the CNTFETs. The considered circuits are shown to be capable of delivering the maximum 35 tuning frequency in the order of 1 GHz to 5 GHz. A major power thirsty part of the high-frequency ring VCOs is the Schmitt trigger stage. Here, several fast and low-power Schmitt trigger topologies are exploited to mitigate the dissipation power and enhance the oscillation frequency.

As a result of proposed modifications, more than one order of magnitude mitigation in the VCO power consumption with respect to the previously presented three-stage CSVCO is reported here. Thus, a VCO dissipation power of 3.5 µW at the frequency of 1.1 GHz and the tuning range of 26 per cent is observed for the well-established 32 nm technology and the supply voltage of 1 V. Such a low dissipation power is obtained around the operating frequency of the battery-powered cellular phones. In addition, using the p-carrier mobility compensation and enhancing the rise time of the Schmitt trigger part of the CSVCO, a maximum of 2.38 times higher oscillation frequency and 72 per cent wider tuning range with respect to Rahane and Kureshi (2017) are observed. Simultaneously, this topology exhibits an average of 20 per cent reduction in the power consumption.

Several new VCO topologies are presented here, and it is shown that they can significantly enhance the power dissipation of the GHz CSVCOs.

The barriers to integrating sustainable practices into construction project management require extensive resource allocations to resolve. Within developing countries such as Iran (where resources are scarce), remedial strategies adopted must prioritise tackling those barriers that can be expected to yield maximum return on investment. The candidate barriers are many, and this paper aims to identify a hierarchy of barriers, providing a priority list of remedial targets.

A mixed philosophical stance of interpretivism and post-positivism is adopted within a deductive approach and survey strategy. A list of 30 known barriers are identified from extant literature and used to formulate a questionnaire data collection instrument administered within the Iranian construction industry. Data collected from 176 practitioners are analysed using the relative importance index and Mann–Whitney U test to compare groups based on the participants' demographic variables.

The findings challenge the common assumption that items related to market and workforce experience are major inhibitors of change. That is, economics and regulatory dependent barriers have a higher impact on the failure of a shift to sustainable practices in Iran. The most influential barriers to incorporating sustainability in construction projects are: (1) lack of understanding of the potential benefits; (2) insufficient cooperation among practitioners, research institutions and environmental organisations; and (3) a lack of a systematic approach to pursuing sustainability goals. No significant associations are detected between the affiliation of the respondents and their attitude towards the issue. Thus, a generalised approach can be applied to a broader range of organisations and construction projects in Iran.

While studies on sustainability impediments at the firm or project level are ubiquitous within literature, this research identifies that the most significant barriers to sustainable project management in Iran, as an underexplored context, are those experienced at the economic and institutional level. Moreover, this novel research presents important insights into the potential effects of participants' demographic profiles on their view of the importance of identified barriers.

This paper presents a pioneering investigation into the barriers impeding the adoption of reverse logistics (RL) in the Iranian construction industry, addressing a significant gap in the current literature within the country.

Through a meticulous examination of the literature, complemented by 19 in-depth interviews, a battery of barriers to RL implementation was initially identified, distilled into a final set of 30 barriers, which served as the basis for the design of a structured survey questionnaire. Employing Partial Least Squares–Structural Equation Modeling (PLS-SEM), an analysis was conducted on a dataset that comprised of 80 responses. Subsequently, the barriers approved through the PLS- SEM were subjected to prioritization through the application of Fuzzy TOPSIS.

Findings reveal the critical inadequacy of contemporary technology and infrastructure, a foundation essential for the efficacious enactment of RL. This shortfall manifests in procurement and logistics processes plagued by inefficiency and ineffectiveness, as consequences of an immature information and technology ecosystem. Furthermore, the study underscores the dominance of traditional markets where the adoption of secondary materials/products remains sporadic, signaling a crucial area for further research and intervention.

This study offers original insights into the significant hurdles that hinder the adoption and integration of RL practices within the Iranian construction industry, an under-explored area within the RL research domain. For industry practitioners, findings point to recommendations for overcoming these barriers in the specific Iranian context while also offering broader insights and lessons that may be relevant to other countries and similar contexts.

Reverse logistics (RL) is a waste revaluation process aimed at reintroducing once-used materials back into the production cycle. Public administration (PA) plays a strong role in influencing the implementation of RL in the construction industry through policy and laws. While much research identifies PA as an important driver in RL, no research yet describes how this occurs.

A systematic literature review was conducted on the theme PA in RL with 93 relevant publications retrieved.

Six strategies used by PA to promote RL were extracted: (1) legislation, (2) government subsidies, (3) landfill disposal fee, (4) government inspection, (5) use in public construction works and (6) penalties and fines. Moreover, a typology built on these six strategies was developed, mapping 15 interactional relationships between strategies, according to three levels of influence: (1) encouragement (2) requirement and (3) regulation.

It was found that legislation and government subsidies prove to be the more effective strategies, with the remaining strategies greatly neglected. Importantly, however, this study reveals that a combination of strategies are most effective when appropriately combined.

This study confirms the importance of PA in RL, in construction, while documenting the extent of current research. The resulting proposed typology, along with 15 identified future research priorities, is expected to be of value to academics and policy makers looking to advance understanding in this domain.

The built environment is a major source of carbon emissions. However, 80 per cent of the damage arises through the operational phase of a building’s life. Office buildings are the most significant building type in terms of emission-reduction potential. Yet, little research has been undertaken to examine the barriers faced by building operators in transitioning to a green operation of the office buildings in their care. This study aims to identify those barriers.

Building facilities managers with between 7 and 25 years’ experience in operating primarily Melbourne high-rise office buildings were interviewed. The sample was taken from LinkedIn connections, with ten agreeing to participate in semi-structured interviews – out of the 17 invitations sent out. Interview comments were recorded, coded and categorised to identify the barriers sought by this study.

Seven categories of barriers to effecting green operation of office buildings were extracted. These were financial, owner-related, tenant-related, technological, regulatory, architectural and stakeholder interest conflicts. Difficulties identifying green operation strategies that improved cost performance or return on investment of buildings was the major barrier.

Government, policymakers and facilities managers themselves have been struggling with how to catalyse a green transition in the operation of office buildings. By identifying the barriers standing in the way, this study provides a concrete point of departure from which remedial strategies and policies may be formulated and put into effect.

The uptake of green operation of office buildings has been extremely slow. Though barriers have been hypothesised in earlier works, this is the first study, to the best of the authors’ knowledge, that categorically identifies and tabulates the barriers that stand in the way of improving the green operational performance of office buildings, drawing on the direct knowledge of facilities experts.

This research paper adopts the fundamental tenets of advanced technologies in industry 4.0 to monitor the structural health of concrete beam members using cost-effective non-destructive technologies. In so doing, the work illustrates how a coalescence of low-cost digital technologies can seamlessly integrate to solve practical construction problems.

A mixed philosophies epistemological design is adopted to implement the empirical quantitative analysis of “real-time” data collected via sensor-based technologies streamed through a Raspberry Pi and uploaded onto a cloud-based system. Data was analysed using a hybrid approach that combined both vibration-characteristic-based method and linear variable differential transducers (LVDT).

The research utilises a novel digital research approach for accurately detecting and recording the localisation of structural cracks in concrete beams. This non-destructive low-cost approach was shown to perform with a high degree of accuracy and precision, as verified by the LVDT measurements. This research is testament to the fact that as technological advancements progress at an exponential rate, the cost of implementation continues to reduce to produce higher-accuracy “mass-market” solutions for industry practitioners.

Accurate structural health monitoring of concrete structures necessitates expensive equipment, complex signal processing and skilled operator. The concrete industry is in dire need of a simple but reliable technique that can reduce the testing time, cost and complexity of maintenance of structures. This was the first experiment of its kind that seeks to develop an unconventional approach to solve the maintenance problem associated with concrete structures. This study merges industry 4.0 digital technologies with a novel low-cost and automated hybrid analysis for real-time structural health monitoring of concrete beams by fusing several multidisciplinary approaches into one integral technological configuration.

This study aims to present an architectural application of 4D-printed climate-adaptive kinetic architecture and parametric façade design.

This work investigates experimental prototyping of a reversibly self-shaping façade, by integrating the parametric design approach, smart material and 4D-printing techniques. Thermo-responsive building skin modules of two-way shape memory composite (TWSMC) was designed and fabricated, combining the shape memory alloy fibers (SMFs) and 3D-printed shape memory polymer matrices (SMPMs). For geometry design, deformation of the TWSMC was simulated with a dimension-reduced mathematical model, and an optimal arrangement of three different types of TWSMC modules were designed and fabricated into a physical scale model.

Model-based experiments show robust workability and formal reversibility of the developed façade. Potential utility of this module for adaptive building design and construction is discussed based on the results. Findings help better understand the shape memory phenomena and presented design-inclusive technology will benefit architectural communities of smart climate-adaptive building.

Two-way reversibility of 4D-printed composites is a topic of active research in material science but has not been clearly addressed in the practical context of architectural design, due to technical barriers. This research is the first architectural presentation of the whole design procedure, simulation and fabrication of the 4D-printed and parametrically movable façade.