An empirical investigation of the learning effect in concrete operations

2018 ◽  
Vol 25 (3) ◽  
pp. 342-357 ◽  
Author(s):  
Roberta Pellegrino ◽  
Nicola Costantino

Purpose The purpose of this paper is to focus on productivity as it unfolds during the execution of a particular task, i.e., reinforced concrete operations. The main aim is understanding whether the learning effect explaining the improvement of productivity in subsequent cycles of a given repetitive construction process is mainly attributable to a pure worker learning (independent on the specific site) or to the experience developed by the crew on the site conditions. Design/methodology/approach The authors conduct a research that empirically investigates and compares the change in productivity data of a single worker during his/her working life and that of a crew involved in specific repetitive work, such as the concreting activities of a multi-storey building. Findings The findings suggest differentiating between productivity gain as a result of the learning effect of the individual worker throughout his/her working life (which is independent of the specific project and site) and that of a crew composed by more workers which repeat reinforced concrete operations in a given specific project. Research limitations/implications Despite the great attention reserved to learning in construction, few researchers discuss on the real applicability of the learning curve (LC) theory in the construction industry. The authors contribute to this literature by empirically investigating the contributions that the learning effect of the individual worker and that of a crew repeating a given task (i.e. reinforced concrete operations) in a given project have on the productivity improvement for subsequent cycles of the repetitive construction process. Practical implications The findings of this study have important managerial implications. The shape of the LC of the individual worker implies that learning increases relatively slowly in his/her working life (particularly after one to two years), while the effects of the crew experience are immediately significant in a time range of few weeks. This means that a single “one-off” multi-storey building project will show in the first storey the “historical,” individual productivity of the individual workers (i.e. not going to vary significantly in the next few weeks). The productivity improvement in the further storeys will only depend on the project-specific (and collective, for the crew) “learning” due, for example, to better coordination or to other issues that are progressively solved moving from the first storey to the following ones. So, the project-specific LC increases in a faster way than the individual one, and the overall productivity can be improved by accelerating the project-specific learning rate with more accurate project-specific design and management. Originality/value This paper enhances the understanding of the contributions that the learning effect of the individual worker and that of a crew repeating a given task (i.e. reinforced concrete operations) in a given project have on the productivity improvement for subsequent cycles of the repetitive construction process. This will contribute to improve the planning and control of site work activities, avoiding time and money wastefulness.

2011 ◽  
Vol 56 (1) ◽  
pp. 148-153 ◽  
Author(s):  
Marisa H. Miceli ◽  
Stella M. Bernardo ◽  
T. S. Neil Ku ◽  
Carla Walraven ◽  
Samuel A. Lee

ABSTRACTInfections and thromboses are the most common complications associated with central venous catheters. Suggested strategies for prevention and management of these complications include the use of heparin-coated catheters, heparin locks, and antimicrobial lock therapy. However, the effects of heparin onCandida albicansbiofilms and planktonic cells have not been previously studied. Therefore, we sought to determine thein vitroeffect of a heparin sodium preparation (HP) on biofilms and planktonic cells ofC. albicans. Because HP contains two preservatives, methyl paraben (MP) and propyl paraben (PP), these compounds and heparin sodium without preservatives (Pure-H) were also tested individually. The metabolic activity of the mature biofilm after treatment was assessed using XTT [2,3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide] reduction and microscopy. Pure-H, MP, and PP caused up to 75, 85, and 60% reductions of metabolic activity of the mature preformedC. albicansbiofilms, respectively. Maximal efficacy against the mature biofilm was observed with HP (up to 90%) compared to the individual compounds (P< 0.0001). Pure-H, MP, and PP each inhibitedC. albicansbiofilm formation up to 90%. A complete inhibition of biofilm formation was observed with HP at 5,000 U/ml and higher. When tested against planktonic cells, each compound inhibited growth in a dose-dependent manner. These data indicated that HP, MP, PP, and Pure-H havein vitroantifungal activity againstC. albicansmature biofilms, formation of biofilms, and planktonic cells. Investigation of high-dose heparin-based strategies (e.g., heparin locks) in combination with traditional antifungal agents for the treatment and/or prevention ofC. albicansbiofilms is warranted.


2017 ◽  
Vol 31 (2) ◽  
pp. 253-268 ◽  
Author(s):  
Sophie Soklaridis ◽  
Ayelet Kuper ◽  
Cynthia R. Whitehead ◽  
Genevieve Ferguson ◽  
Valerie H. Taylor ◽  
...  

Purpose The purpose of this paper is to examine the experiences of gender bias among women hospital CEOs and explore to what these female leaders attribute their success within a male-dominated hospital executive leadership milieu. Design/methodology/approach This qualitative study involved 12 women hospital CEOs from across Ontario, Canada. Purposeful sampling techniques and in-depth qualitative interview methods were used to facilitate discussion around experiences of gender and leadership. Findings Responses fell into two groups: the first group represented the statement “Gender inequality is alive and well”. The second group reflected the statement “Gender inequity is not significant, did not happen to me, and things are better now”. This group contained a sub-group with no consciousness of systemic discrimination and that claimed having no gendered experiences in their leadership journey. The first group described gender issues in various contexts, from the individual to the systemic. The second group was ambivalent about gender as a factor impacting leadership trajectories. Originality/value Representations of women’s leadership have become detached from feminism, with major consequences for women. This study reveals how difficult it is for some women CEOs to identify gender bias. The subtle everyday norms and practices within the workplace make it difficult to name and explain gender bias explicitly and may explain the challenges in understanding how it might affect a woman’s career path.


2018 ◽  
Vol 47 (4) ◽  
pp. 350-359 ◽  
Author(s):  
Nivin M. Ahmed ◽  
Mostafa G. Mohamed ◽  
Reham H. Tammam ◽  
Mohamed R. Mabrouk

Purpose This study aims to apply novel anticorrosive pigments containing silica fume-phosphates (Si-Ph), which were prepared using core-shell technique by covering 80-90 per cent silica fume (core) with 10-20 per cent phosphates (shell) previously, to play dual functions simultaneously as anticorrosive pigments in coating formulations and as an anticorrosive admixture in concrete even if it is not present in the concrete itself. Two comparisons were held out to show the results of coatings on rebars containing core-shell pigments in concrete, and concrete admixtured with silica fume can perform a dual function as anticorrosive pigment and concrete admixture. The evaluation of corrosion protection efficiency of coatings containing core-shell pigments and those containing phosphates was performed. Design/methodology/approach Simple chemical techniques were used to prepare core-shell pigments, and their characterization was carried out in a previous work. These pigments were incorporated in solvent-based paint formulations based on epoxy resin. Different electrochemical techniques such as open-circuit potential and electrochemical impedance spectroscopy were used to evaluate the anticorrosive efficiency of the new pigments. Findings The electrochemical measurements showed that concrete containing coated rebars with core-shell pigments exhibited almost similar results to that of concrete admixtured with silica fume. Also, the anticorrosive performance of coatings containing Si-Ph pigments offered protection efficiency almost similar to that of phosphates, proving that these new pigments can perform both roles as anticorrosive pigment and concrete admixture. Originality/value Although the new Si-Ph pigments contain more than 80 per cent waste material, its performance can be compared to original phosphate pigments in the reinforced concrete.


2015 ◽  
Vol 19 (3) ◽  
pp. 433-455 ◽  
Author(s):  
Christina Ling-hsing Chang ◽  
Tung-Ching Lin

Purpose – The purpose of the study is to focus on the enhancement of knowledge management (KM) performance and the relationship between organizational culture and KM process intention of individuals because of the diversity of organizational cultures (which include results-oriented, tightly controlled, job-oriented, closed system and professional-oriented cultures). Knowledge is a primary resource in organizations. If firms are able to effectively manage their knowledge resources, then a wide range of benefits can be reaped such as improved corporate efficiency, effectiveness, innovation and customer service. Design/methodology/approach – The survey methodology, which has the ability to enhance generalization of results (Dooley, 2001), was used to collect the data utilized in the testing of the research hypotheses. Findings – Results- and job-oriented cultures have positive effects on employee intention in the KM process (creation, storage, transfer and application), whereas a tightly controlled culture has negative effects. Research limitations/implications – However, it would have been better to use a longitudinal study to collect useful long-term data to understand how the KM process would be influenced when organizational culture dimensions are changed through/by management. This is the first limitation of this study. According to Mason and Pauleen (2003), KM culture is a powerful predictor of individual knowledge-sharing behavior, which is not included in this study. Thus, this is the second limitation of this paper. Moreover, national culture could be an important issue in the KM process (Jacks et al., 2012), which is the third limitation of this paper for not comprising it. Practical implications – In researchers’ point of view, results- and job-oriented cultures have positive effects, whereas a tightly controlled culture has a negative effect on the KM process intention of the individual. These findings provide evidences that challenge the perspective of Kayworth and Leidner (2003) on this issue. As for practitioners, management has a direction to modify their organizational culture to improve the performance of KM process. Social implications – Both behavioral and value perspectives of the organizational cultural dimensions (results-oriented, tightly control, job-oriented, sociability, solidarity, need for achievement and democracy) should be examined to ascertain their effects firstly on KM culture and then on the KM process intention of the individual. It is hoped that the current study will spawn future investigations that lead to the development of an integrated model which includes organizational culture, KM culture and the KM process intention of the individual. Originality/value – The results-oriented, loosely controlled and job-oriented cultures will improve the effectiveness of the KM process and will also increase employees’ satisfaction and willingness to stay with the organization.


2020 ◽  
Vol 11 (3) ◽  
pp. 447-460
Author(s):  
Nan Hua

Purpose This paper aims to examine the impacts of IT capabilities on hotel competitiveness. Design/methodology/approach This study adapts and extends Hua et al. (2015) and O’Neill et al. (2008) by incorporating the specific measures of IT expenditures as proxies for the relevant IT capabilities to explore the impacts of IT capabilities on hotel competitiveness. Findings This study finds that expenditures on IT Labor, IT Systems and IT Websites exert different impacts on hotel competitiveness. In addition, IT capabilities exert both contemporary and lagged effects on hotel competitiveness. Originality/value This study is the first that uses financial data to capture direct measures of individual IT capabilities and tests the individual impacts of IT capabilities on hotel competitiveness from both contemporaneous and lagged perspectives. It uses a large same store sample of hotels in the USA from 2011 to 2017; as a result, the study results can be reasonably representative of the hotel population in the USA.


2020 ◽  
Vol 37 (7) ◽  
pp. 2517-2537
Author(s):  
Mostafa Rezvani Sharif ◽  
Seyed Mohammad Reza Sadri Tabaei Zavareh

Purpose The shear strength of reinforced concrete (RC) columns under cyclic lateral loading is a crucial concern, particularly, in the seismic design of RC structures. Considering the costly procedure of testing methods for measuring the real value of the shear strength factor and the existence of several parameters impacting the system behavior, numerical modeling techniques have been very much appreciated by engineers and researchers. This study aims to propose a new model for estimation of the shear strength of cyclically loaded circular RC columns through a robust computational intelligence approach, namely, linear genetic programming (LGP). Design/methodology/approach LGP is a data-driven self-adaptive algorithm recently used for classification, pattern recognition and numerical modeling of engineering problems. A reliable database consisting of 64 experimental data is collected for the development of shear strength LGP models here. The obtained models are evaluated from both engineering and accuracy perspectives by means of several indicators and supplementary studies and the optimal model is presented for further purposes. Additionally, the capability of LGP is examined to be used as an alternative approach for the numerical analysis of engineering problems. Findings A new predictive model is proposed for the estimation of the shear strength of cyclically loaded circular RC columns using the LGP approach. To demonstrate the capability of the proposed model, the analysis results are compared to those obtained by some well-known models recommended in the existing literature. The results confirm the potential of the LGP approach for numerical analysis of engineering problems in addition to the fact that the obtained LGP model outperforms existing models in estimation and predictability. Originality/value This paper mainly represents the capability of the LGP approach as a robust alternative approach among existing analytical and numerical methods for modeling and analysis of relevant engineering approximation and estimation problems. The authors are confident that the shear strength model proposed can be used for design and pre-design aims. The authors also declare that they have no conflict of interest.


2019 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Maria Elo ◽  
Leo-Paul Dana

Purpose The purpose of this paper is to explore how entrepreneurship traditions evolve in diaspora. Design/methodology/approach A qualitative multiple case study examining the role of diaspora embeddedness, extended family, ethno-religious-, cultural- and social ties and relevant structures shaping diaspora entrepreneurship. Findings The authors found that social ties and diaspora embeddedness create dynamism fostering entrepreneurial identity as a part of the Bukharian culture, and as a preferred career option in the context of Bukharian Jews in diaspora. Diasporic family businesses are products of culture and tradition that migrate to new locations with families and communities, not as disconnected business entities. Research limitations/implications The ways in which families nurture a highly entrepreneurial culture that transfers across generations and contexts are context-specific and not per se generalizable to other diasporas. Practical implications Diasporans often continue their traditions and become again entrepreneurs after their settlement, or they may generate hybrid, circular solutions that allow them to employ their competences in the new contexts or connecting various contexts. This calls for transnational entrepreneurship-policymaking. Social implications Time changes diasporas. A long-term commitment to the business environment evolves and reduces the mobility of the individual diasporan; typically the children of these migrants become more integrated and develop divergent career paths. Hence, their plans are not necessarily including family entrepreneurship creating a challenge for continuation of the original culture of entrepreneurship. Originality/value Despite a notable tradition in Jewish studies, there is limited research on Jewish entrepreneurial diaspora and its contemporary entrepreneurial identity and tradition. Furthermore, the population of Bukharian Jews is an unknown and under-explored highly entrepreneurial group that may offer instrumental views to larger diasporic audiences being concerned about maintaining notions of ethnic heritage and identity.


2013 ◽  
Vol 61 (1) ◽  
pp. 32-37 ◽  
Author(s):  
Guofu Qiao ◽  
Yi Hong ◽  
Tiejun Liu ◽  
Jinping Ou

Purpose – The aim of this paper was to investigate the passive corrosion control and active corrosion protective effect of the reinforced concrete structures by electrochemical chloride removal (ECR) method and inhibitors approach, respectively. Design/methodology/approach – The concentration of aggressive chloride ion distributed from the reinforcing steel to the surface of the concrete cover was analyzed during the ECR processes. Besides, the half-cell potential, the concrete resistance R c , the polarization resistance R p and the capacitance of double layer C dl of the steel/concrete system were used to characterize the electrochemical performance of the concrete prisms. Findings – The effectiveness of ECR could be enhanced by increasing the amplitude of potential or prolonging the time. Inhibitor SBT-ZX(I) could successfully prevent the corrosion development of the reinforcing steel in concrete. Originality/value – The research provides the scientific basis for the practical application of ECR and inhibitors in the field.


2015 ◽  
Vol 28 (1) ◽  
pp. 45-76 ◽  
Author(s):  
Claudio Mancilla ◽  
José Ernesto Amorós

Purpose The purpose of this paper is to study the differentiated impact of factors that influence the propensity to entrepreneur in a sample of people in Chile. A distinction is made between individuals that live in primary cities and secondary cities. The differentiating factors are socio‐cultural aspects (reference models – positive examples of entrepreneurs – and perception of social fear of failure) and the gender of the individual. Design/methodology/approach For the research data from the survey used in Chile by the Global Entrepreneurship Monitor for the years 2010 and 2011 were used. A logit model was used to determine the differentiated impact of the analysed factors and interactions were done using the method proposed by Corneliâen and Sonderhof (2009). Findings These showed that the fact that an individual lives in a secondary city decreases his entrepreneurship probability. The positive impact that the reference models have is weaker in women. Contrary to what was expected, the negative impact of the fear of failure perception is weaker in women. Practical implications These results have the implications to suggest focused public policies and differentiations that consider the socio‐cultural, territorial (focused in cities) and gender aspects. Originality/value The research contributes by giving empirical evidence of the existence of the negative impact of living in a secondary city and of differentiated effects of socio‐cultural factors from the gender perspective.


2011 ◽  
Vol 77 (13) ◽  
pp. 4669-4675 ◽  
Author(s):  
Dawn C. Bisi ◽  
David J. Lampe

ABSTRACTThe insect-vectored disease malaria is a major world health problem. New control strategies are needed to supplement the current use of insecticides and medications. A genetic approach can be used to inhibit development of malaria parasites (Plasmodiumspp.) in the mosquito host. We hypothesized thatPantoea agglomerans, a bacterial symbiont ofAnophelesmosquitoes, could be engineered to express and secrete anti-Plasmodiumeffector proteins, a strategy termed paratransgenesis. To this end, plasmids that include thepelBorhlyAsecretion signals from the genes of related species (pectate lyase fromErwinia carotovoraand hemolysin A fromEscherichia coli, respectively) were created and tested for their efficacy in secreting known anti-Plasmodiumeffector proteins (SM1, anti-Pbs21, and PLA2) inP. agglomeransandE. coli.P. agglomeranssuccessfully secreted HlyA fusions of anti-Pbs21 and PLA2, and these strains are under evaluation for anti-Plasmodiumactivity in infected mosquitoes. Varied expression and/or secretion of the effector proteins was observed, suggesting that the individual characteristics of a particular effector may require empirical testing of several secretion signals. Importantly, those strains that secreted efficiently grew as well as wild-type strains under laboratory conditions and, thus, may be expected to be competitive with the native microbiota in the environment of the mosquito midgut.


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