Decision Support Model For Construction Crew Reassignments

The reassignment of crews on a construction project in response to changes occurs on a frequent basis. The factors that affect the crew reassignment decision can be myriad and most are not known with certainty. This research addresses the need for a decision support model to assist construction managers with the crew reassignment problem. The model design makes use of certainty factors in a decision tree structure. The research helped to determine the elements in the decision tree, the appropriate combination rules to use with the certainty factors, and the method for combining the certainty factors and costs to develop a measure of cost for each decision option. The research employed surveys, group meetings, and individual interviews of experienced construction managers and superintendents to investigate the current methods used by decision makers to identify and evaluate the key elements of the construction crew reassignment decision. The initial research indicated that the use of certainty factors was preferred over probabilities for representing the uncertainties. Since certainty factors have not been used in a traditional decision tree context, a contribution of the research is the development and testing of techniques for combining certainty factors, durations, and costs in order to represent the uncertainty and to emulate the decision process of the experts interviewed. The developed model provides the decision maker with an estimate of upper and lower bounds of costs for each crew reassignment option. The model was applied contemporaneously to six changes on three ongoing construction projects to test the model and assess its usefulness. The model provides a previously unavailable tool for the prospective identification and estimation of productivity losses and potential costs that emanate from changes. The users indicated the model process resulted in concise and complete compilations of the elements of the crew reassignment decision and that the model outputs were consistent with the users\u27 expectations

Wellbeing in Workers during COVID-19 Pandemic: The Mediating Role of Self-Compassion in the Relationship between Personal Resources and Exhaustion

Italy was the second country to be affected by COVID-19 in early 2020, after China. The confrontation with the pandemic led to great changes in the world of work and, consequently, to the personal world of workers. In such a challenging situation, it is essential to be able to rely on resources that facilitate individual coping. The aim of this study was to understand the association between personal resources (optimism and humor) and exhaustion, and the role of self-compassion in this relationship. A structural equation model (SEM) was used to test the hypotheses on a heterogeneous sample of 422 Italian workers during the first lockdown in April–May 2020. The results revealed that optimism and humor were positively associated with self-compassion; optimism and humor also had a negative association with exhaustion; and self-compassion had a mediating role between the two personal resources and exhaustion. These results confirmed the importance of personal resources in maintaining workers’ wellbeing during a challenging period such as the pan-demic. The present study also contributes to the body of knowledge on self-compassion, a relatively new construct that has been little studied in the organizational field

Rationalizing the Lacking of Inversion Symmetry in a Noncentrosymmetric Polar Racemate : an Experimental and Theoretical Study

The total charge density of PYRAC, a polar (Pca21) organic racemate with Z\u2032 = 2, was derived from high-resolution single-crystal X-ray diffraction data at T = 100(2) K and periodic DFT calculations. The PYRAC asymmetric unit consists of a hydrogen-bonded pair of conformationally different enantiomers, A and Bi, where the subscript \u201ci\u201d indicates a reversed absolute configuration. The lattice stability was compared with that of centrosymmetric possibly competing structures, with the aim of understanding why a noncentrosymmetric lattice framework is obtained from a racemic mixture. The likelihood of specific intermolecular recognition processes among different conformers of PYRAC in the very first stages of nucleation was investigated by DFT simulations in vacuo. Two competing, equivalent interconversion pseudorotatory paths between the most stable A and the least stable B conformers were found. It results that molecules spend most of their time ( 4853%) in the A conformation, whereas the B one is far less populated ( 487%). Therefore, centrosymmetric AAi adducts are formed very frequently in the reaction liquor, whereas the BBi ones are rare. Nevertheless, AAi pairs produce crystal forms with cohesive energies and densities significantly less favorable than those estimated for the noncentrosymmetric heterochiral ABi ones. Therefore, preference for Z\u2032 = 2 in conjunction with noncentrosymmetric point and space groups results from the thermodynamic control of the crystallization process. The capability of forming extended hydrogen bond chains throughout the lattice appears to be a prerequisite to bind together the fundamental ABi repeating units

Manejo sostenible de los bosques tropicales. Desafíos para las prácticas de aprovechamiento de impacto reducido.

bitstream/item/173662/1/Manejo-sostenible.pd

Well-being, work comfort and food security are better than maximizing production in the Amazon.

In the Amazon, slash and burn is the most common technique used by American-Indians, small farmers and even big ranches to transform forests into rural landscapes. The basis of food subsistence for diverse populations (rice, corn and bean), slash and burn is also a must for the plantation of cocoa, coffee, palms and pastures. The Amazonian rural landscape is currently dominated by pastures, occupying around 80 % of the deforested surface. Even if the nature of the plantation varies according to location, height, soil type and local traditions, slash and burn remains relatively the same in all regions. Agro-ecological intensification and the integration of livestock and agriculture is 2-3 decades old. Different alternatives have been tested, particularly the introduction of leguminous (covering the land or forming trees) to improve the soil and to build a bank of proteins for cattle. New techniques for the recuperation of pasture lands have become widely popular among ranches. The introduction of one or two annual plantations between two pasture areas allows reestablishing fertility through the injection of nitrates and, as a result, increases the pasture?s productivity. However, being relatively high-cost because of its demand in terms of mechanization and inputs, this technique is almost unaffordable for small Amazonian farmers..

Long term Impact of logging on carbon storage and tree diversity in the Amazon Basin.

KANSHIRO [i.e. KANASHIRO], M

Manejo florestal comunitário e familiar: percepções de pequenos produtores rurais na BR-163 e BR-230, Pará.

O Manejo Florestal Comunitário e Familiar (MFCF) tomou-se promissora alternativa de renda para povos tradicionais e comunidades rurais. Dentre os beneficiários das políticas do MFCF (i.e. Decreto n° 6.874/09) estão colonos de assentamentos rurais. Estes, embora motivados pelo dinheiro e pela melhoria das infraestruturas locais, não recebem assistência técnica e outros tipos de apoio institucionais necessários que conduzem ao sucesso da atividade. Nesse contexto, este trabalho analisou as características de alguns contratos formais celebrados entre assentados e o setor madeireiro na BR-163 e BR-230, estado do Pará, dando enfoque nas percepções dos produtores rurais quanto às relações entre atores locais e regionais que atuam nos assentamentos e que estão envolvidos de alguma forma no manejo florestal madeireiro na região do estudo. Observou-se que as melhores relações são aquelas em que os atores mantém presença física nos assentamentos e que, órgãos importantes, como o SFB, não têm visibilidade de suas ações nessas localidades, mostrando gargalos na implementação de programas governamentais de apoio ao MFCF. Observou-se também que as lideranças possuem uma percepção mais complexa das relações entre os atores. Para melhorias, sugere-se maior abertura no diálogo entre governo e produtores rurais e apoio técnico através de assistência técnica e extensão florestal