Dhanasekar R, Ganesh Kumar Srinivasan and Marco Rivera
The purpose of this study is to stabilize the rotating speed of the permanent magnet direct current (PMDC) motor driven by a DC-DC boost converter under mismatched disturbances…
Abstract
Purpose
The purpose of this study is to stabilize the rotating speed of the permanent magnet direct current (PMDC) motor driven by a DC-DC boost converter under mismatched disturbances (i.e.) under varying load circumstances like constant, frictional, fan type, propeller and undefined torques.
Design/methodology/approach
This manuscript proposes a higher order sliding mode control to elevate the dynamic behavior of the speed controller and the robustness of the PMDC motor. A second order classical sliding surface and proportional-integral-derivative sliding surface (PIDSS) are designed and compared.
Findings
For the boost converter with PMDC motor, both simulation and experimentation are exploited. The prototype is built for an 18 W PMDC motor with field programmable gate arrays. The suggested sliding mode with second order improves the robustness of the arrangement under disturbances with a wide range of control. Both the simulation and experimental setup shows satisfactory results.
Originality/value
According to software-generated mathematical design and experimental findings, PIDSS exhibits excellent performance with respect to settling speed, steady-state error and peak overshoot.
Details
Keywords
Rakesh Sai Kumar Mandala and R. Ramesh Nayaka
This paper aims to identify modern construction techniques for affordable housing, such as prefabrication and interlocking systems, that can save time and cost while also…
Abstract
Purpose
This paper aims to identify modern construction techniques for affordable housing, such as prefabrication and interlocking systems, that can save time and cost while also providing long-term sustainable benefits that are desperately needed in today's construction industry.
Design/methodology/approach
The need for housing is growing worldwide, but traditional construction cannot cater to the demand due to insufficient time. There should be some paradigm shift in the construction industry to supply housing to society. This paper presented a state-of-the-art review of modern construction techniques practiced worldwide and their advantages in affordable housing construction by conducting a systematic literature review and applying the backward snowball technique. The paper reviews modern prefabrication techniques and interlocking systems such as modular construction, formwork systems, light gauge steel/cold form steel construction and sandwich panel construction, which have been globally well practiced. It was understood from the overview that modular construction, including modular steel construction and precast concrete construction, could reduce time and costs efficiently. Further enhancement in the quality was also noticed. Besides, it was observed that light gauge steel construction is a modern phase of steel that eases construction execution efficiently. Modern formwork systems such as Mivan (Aluminium Formwork) have been reported for their minimum construction time, which leads to faster construction than traditional formwork. However, the cost is subjected to the repetitions of the formwork. An interlocking system is an innovative approach to construction that uses bricks made of sustainable materials such as earth that conserve time and cost.
Findings
The study finds that the prefabrication techniques and interlocking system have a lot of unique attributes that can enable the modern construction sector to flourish. The study summarizes modern construction techniques that can save time and cost, enhancing the sustainability of construction practices, which is the need of the Indian construction industry in particular.
Research limitations/implications
This study is limited to identifying specific modern construction techniques for time and cost savings, lean concepts and sustainability which are being practiced worldwide.
Practical implications
Modern formwork systems such as Mivan (Aluminium Formwork) have been reported for their minimum construction time which leads to faster construction than traditional formwork.
Social implications
The need for housing is growing rapidly all over the world, but traditional construction cannot cater to the need due to insufficient time. There should be some paradigm shift in the construction industry to supply housing to society.
Originality/value
This study is unique in identifying specific modern construction techniques for time and cost savings, lean concepts and sustainability which are being practiced worldwide.
Details
Keywords
Deployment of optimal size of resources is a key issue in repetitive construction projects. This paper describes a simulation model based on queuing theory for the resource…
Abstract
Deployment of optimal size of resources is a key issue in repetitive construction projects. This paper describes a simulation model based on queuing theory for the resource scheduling of a real repetitive housing project involving 320 dwelling units constructed in East Delhi, India. The optimal size of resources, defined as the minimum size required to keep the project duration a minimum, has been identified from the results of a series of sensitivity analyses in which the size of the resources was varied one at a time. The duration of the project, the period of utilization of the resources, and the queue length of activities waiting for service are also reported in this paper. It has been shown that reduction in size of resources is achievable without increasing the duration of the project and queue length of activities. Increase in the size of some specialised crews is also proved advantageous.
Details
Keywords
Yuvaraj Dhanasekar and K.S. Anandh
The study investigates the impact of gender and age on the perception of organizational politics among construction professionals in Tamil Nadu, India, a region with unique…
Abstract
Purpose
The study investigates the impact of gender and age on the perception of organizational politics among construction professionals in Tamil Nadu, India, a region with unique sociocultural characteristics, which highlights the significance of a diverse, inclusive and equitable workplace.
Design/methodology/approach
A self-administered questionnaire was used to collect data from 251 construction professionals. The study focused on three key aspects of organizational politics perception: general political behavior, go along to get ahead and pay and promotion policies. Data were examined using descriptive statistics, the Mann-Whitney U test and regression analysis with the help of SPSS V23.
Findings
The study reveals that female professionals in the sample may be more sensitive to go along to get ahead and pay and promotion policies than their male counterparts, particularly those aged 29–38. The study also found significant gender-age interactions in organizational politics perception, with females experiencing a greater impact of age on general political behavior, go along to get ahead and pay and promotion policies.
Practical implications
The findings can help managers and practitioners design better interventions and policies to mitigate the negative effects of organizational politics, improve employee satisfaction and performance and foster a more diverse and fair work culture.
Originality/value
This is one of the first studies to explore the influence of gender and age on organizational politics perception in the construction sector, which is characterized by complexity and diversity. The study contributes to the literature on organizational politics and diversity in the construction industry.
Details
Keywords
Puneet Kumar and Gaurav Srivastava
Reinforced concrete structural frames with masonry infills (infill-frames) are commonly used for construction worldwide. While the behavior of such frames has been studied…
Abstract
Purpose
Reinforced concrete structural frames with masonry infills (infill-frames) are commonly used for construction worldwide. While the behavior of such frames has been studied extensively in the context of earthquake loading, studies related to their fire performance are limited. Therefore, this study aims to characterize the behavior of infill-frames under fire exposure by presenting a state-of-the-art literature review of the same.
Design/methodology/approach
Both experimental and computational studies have been included with a special emphasis on numerical modeling (simplified as well as advanced). The cold behavior of the infill-frame and its design requirements in case of fire exposure are first reviewed to set the context. Subsequently, the applicability of numerical modeling strategies developed for modeling cold infill-frames to simulate their behavior under fire is critically examined.
Findings
The major hurdles in developing generic numerical models for analyzing thermo-mechanical behavior of infill-frames are identified as: lack of temperature-dependent material properties, scarcity of experimental studies for validation and idealizations in coupling between thermal and structural analysis.
Originality value
This study presents one of the most popular research problems connected with practical and reliable utilization of numerical models, as a good alternative to expensive traditional furnace testing, in assessing fire resistance of infill-frames. It highlights major challenges in thermo-mechanical modeling of infill-frames and critically reviews the available approaches for modeling infill-frames subjected to fire.
Details
Keywords
Hamdy Mohy Afefy, Salah El‐Din Fahmy Taher, Abdel‐Hakim A. Khalil and Mohamed E. Issa
The most simple equivalent frame system with reduced degrees of freedom is proposed for handling multi‐story multi‐bay infilled frames. The system is composed of homogenized…
Abstract
The most simple equivalent frame system with reduced degrees of freedom is proposed for handling multi‐story multi‐bay infilled frames. The system is composed of homogenized continuum for the reinforced concrete members braced with unilateral diagonal struts for each bay, which are only activated in compression. Identification of the equivalent system characteristics and nonlinear material properties are accomplished from the concepts of inverse analysis approach along with statistical tests of hypotheses is employed to establish the appropriate filtering scheme and the proper accuracy tolerance. The suggested system allows for nonlinear finite element static and dynamic analysis of sophisticated infilled reinforced concrete frames. Sensitivity analysis is undertaken to check the suitability of the proposed system to manipulate various structural applications.
Details
Keywords
Juliet Owusu-Boadi, Ernest Kissi, Ivy Maame Abu, Cecilia Dapaah Owusu, Bernard K. Baiden, Kenneth Eluerkeh and Stephen Nana Opoku Ware
Workforce diversity is essential for success from the perspectives of economic development and intellectual property. However, the construction industry is losing out on these…
Abstract
Purpose
Workforce diversity is essential for success from the perspectives of economic development and intellectual property. However, the construction industry is losing out on these gains due to the low diversity among them. The study aims to identify challenges impeding workforce diversity in construction literature through a mixed review approach.
Design/methodology/approach
The study desk reviewed 188 relevant construction peer-reviewed articles and conference papers with no restrictions on the time range. The study adopted the mixed methodology review approach through bibliometric and systematic content analyses.
Findings
The study identified 67 challenges and further classified them into 4 broad categories. These were industry-related, organisational-, personal or attitudinal- and health-related challenges. Organisational challenges were the most prevalent challenges of diversity uptake in the construction industry. The publications' most influential sources, countries/regions and annual trends were also discussed.
Practical implications
Classifying the challenges hindering diversity contributes to the existing knowledge base. The framework's interrelationships among categorised barriers will enable construction professionals to make informed decisions in promoting diversity in the industry.
Originality/value
This study has a broad geographical reach, allowing the findings to be widely applicable to the diverse practice of the worldwide construction sector.
Details
Keywords
– This paper aims to propose a non-contact method using machine vision for measuring the surface roughness of a rotating workpiece at speeds of up to 4,000 rpm.
Abstract
Purpose
This paper aims to propose a non-contact method using machine vision for measuring the surface roughness of a rotating workpiece at speeds of up to 4,000 rpm.
Design/methodology/approach
A commercial digital single-lens-reflex camera with high shutter speed and backlight was used to capture a silhouette of the rotating workpiece profile. The roughness profile was extracted at sub-pixel accuracy from the captured images using the moment invariant method of edge detection. The average (Ra), root-mean square (Rq) and peak-to-valley (Rt) roughness parameters were measured for ten different specimens at spindle speeds of up to 4,000 rpm. The roughness values measured using the proposed machine vision system were verified using the stylus profilometer.
Findings
The roughness values measured using the proposed method show high correlation (up to 0.997 for Ra) with those determined using the profilometer. The mean differences in Ra, Rq and Rt between the two methods were only 4.66, 3.29 and 3.70 per cent, respectively.
Practical implications
The proposed method has significant potential for application in the in-process roughness measurement and tool condition monitoring from workpiece profile signature during turning, thus, obviating the need to stop the machine.
Originality/value
The machine vision method combined with sub-pixel edge detection has not been applied to measure the roughness of a rotating workpiece.
Details
Keywords
– The purpose of this paper is to investigate the influence of cement/sand ratio on behaviour of cement mortar.
Abstract
Purpose
The purpose of this paper is to investigate the influence of cement/sand ratio on behaviour of cement mortar.
Design/methodology/approach
Literature review was used to confirm that the cement/sand ratio have influence on the mortar strength and that its influence is not very studied. The literature points out also that the constitutive model of mortar is very important in the structural design of masonry but it has not been investigated much.
Findings
The results of study allow to forecast the mortar strength by the cement/sand ratio when the water/cement ratio is fixed (0.50). Besides, the obtained experimental results allow defining a constitutive model for sand mortar.
Research limitations/implications
Other experiments would be proper to extend the research field.
Practical implications
The findings are of particular importance to mix design of cement mortar and to structural design of masonry. In fact, for mortar in the practices, there are no constitutive equations to use in the structural calculation, and so, normally the engineers use the constitutive equations of concrete (very rough). The idea is to find constitutive equations that, using simple and economic tests, allow to engineers to model more correctly the realty.
Originality/value
There are few studies which try to investigate the relationship between the behaviour of cement mortar and cement/sand ratio, as well as to study constitutive model of cement mortar. This paper contributes to bridging that gap.
Details
Keywords
Yang Juping, Junguo Wang and Zhao Yongxiang
The purpose of this paper is to investigate the non-linear characteristics and stability of the rolling bearing–axle coupling system under the excitation of the axle/wheel speed…
Abstract
Purpose
The purpose of this paper is to investigate the non-linear characteristics and stability of the rolling bearing–axle coupling system under the excitation of the axle/wheel speed of railway freight cars, so as to put forward a rationale for judging the vibration law and running stability of railway freight wagon.
Design/methodology/approach
Considering the effects of eccentric force of the railway wagon axle, the non-linear resistance of the wagon and non-linear support forces of axle box rolling bearings, a centralized mass model of rolling bearing-axle coupling system of railway freight wagon is presented on the basis of the theory of rotor dynamics and non-linear dynamics. Then the Runge-Kutta method is adopted to solve the non-linear response of the proposed system, and numerical simulation including bifurcation diagrams, axis trajectory curves, phase plane plots, Poincaré sections and amplitude spectras are analysed when the axle rotating speed is changed. Meantime, the relation curve between Floquet multiplier and axle rotating speed, which affects the stability of coupling system, is plotted by numerical method based on the Floquet theory and method.
Findings
The simulation results of the dynamic model reveal the abundant dynamic behaviour of the coupling system when the axle rotating speed changes, including single period, quasi period, multi-period and chaotic motion, as well as the evolution law from multi-period motion to chaotic motion. And especially, the bearing–axle coupling system is in stable state with a single period motion when the axle rotating speed changes from 410 rpm to 510 rpm, in which the running speed of railway freight wagon is changed from 62 km/h to 80 km/h, the vibration displacement of the coupling system in X direction is between 1.2 mm and 1.8 mm, and the vibration displacement of the coupling system in Y direction is between 1.0 mm and 1.45 mm. Meanwhile, the influence law of axle rotating speed on the stability is obtained by comparing the bifurcation diagram and Floquet multiplier graph of the coupling system.
Originality/value
The numerical simulation data obtained in this study can provide a theoretical evidence for designing the running speed of railway freight wagon, utilizing or controlling the non-linear dynamic behaviours of the proposed coupling system, and ensuring the stability of railway freight wagons.