Evaluating the impacts of iteration on PD processes by transforming task network models into System Dynamics models

Iteration is unavoidable in the design process and should be incorporated when planning and managing projects in order to minimize surprises and reduce schedule distortions. However, planning and managing iteration is challenging because the relationships between its causes and effects are complex. Most approaches which use mathematical models to analyze the impact of iteration on the design process focus on a relatively small number of its causes and effects. Therefore, insights derived from these analytical models may not be robust under a broader consideration of potential influencing factors. In this article, we synthesize an explanatory framework which describes the network of causes and effects of iteration identified from the literature, and introduce an analytic approach which combines a task network modeling approach with System Dynamics simulation. Our approach models the network of causes and effects of iteration alongside the process architecture which is required to analyze the impact of iteration on design process performance. We show how this allows managers to assess the impact of changes to process architecture and to management levers which influence iterative behavior, accounting for the fact that these changes can occur simultaneously and can accumulate in non-linear ways. We also discuss how the insights resulting from this analysis can be visualized for easier consumption by project participants not familiar with simulation methods. Copyright © 2010 by ASME.

Aquaculture technologies in Bangladesh: an assessment of technical and economic performance and producer behavior

This study evaluates the performance of a wide range of aquaculture systems in Bangladesh. It is by far the largest of its kind attempted to date. The purpose of this study was to identify and analyze the most important production systems, rather than to provide a nationally representative overview of the entire aquaculture sector of Bangladesh. As such, the study yields a huge amount of new information on production technologies that have never been thoroughly researched before. The study reveals an extremely diverse array of specialized, dynamic and rapidly evolving production technologies, adapted to a variety of market niches and local environmental conditions. This is a testament to the innovativeness of farmers and other value chain actors who have been the principal drivers of this development in Bangladesh. Data was collected from six geographical hubs. This survey was conducted from November 2011 to June 2012. Technological performance in terms of detailed input and output information, fish management practices, credit and marketing, and social and environmental issues were captured by the survey questionnaire, which had both open and closed format questions. The study generated insights that enable better understanding of aquaculture development in Bangladesh.

Unstable behavior of low and high speed compressors

By far the greater part of our understanding about stall and surge in axial compressors comes from work on low-speed laboratory machines. As a general rule, these machines do not model the compressibility effects present in high-speed compressors and therefore doubt has always existed about the application of low-speed results to high-speed machines. In recent years interest in active control has led to a number of studies of compressor stability in engine type compressors. This paper presents new data from an eight-stage fixed geometry engine compressor and compares this with low-speed laboratory data.

ECOLOGY AND BEHAVIOR OF WILD BLACK-CRESTED GIBBONS (HYLOBATES-CONCOLOR) IN CHINA WITH A RECONSIDERATION OF EVIDENCE FOR POLYGYNY

The black-crested gibbon, Hylobates concolor, is one of the few species of gibbons that has not yet been the subject of a long term field study. Field observations in the Ai Lao and Wu Liang Mountains of Yunnan Province, China indicate that in this area the habitat and ecology of this species differ markedly from those of other gibbons that have been studied to date. These differences are correlated with some behavioral differences. In particular, these gibbons apparently have greater day ranges than other gibbons. It has also been suggested that this species lives in polygynous groups. To demonstrate this requires observation of groups with two or more females with young. Our own observations and those from other recent studies suggest that there are alternative explanations consistent with available data.

SEXUAL-BEHAVIOR OF TIBETAN MACAQUES AT MT EMEI, CHINA

Data on sexual behavior were collected in six groups of semi-commensal Macaca thibetana along the trail on the slope habitat between 1987 and 1989. Ignoring the common items such as mounting, presenting etc., 20 categories of sexual behavior were described. Most of the descriptions were likely to have enlarged the behavior repertoire reported in macaques, showing a great complexity of sociosexual interactions under the principally natural condition. A great diversity of grouping appeared in the mating season. The copulatory pattern was found to be the serial type contrary to previous speculation, and the mount-to-ejaculation ratio was higher in the central subgroup, as compared with the far-peripheral adult subgroup (FAS) with less male and female rivals. An age-class subdivision of sexually active males made it possible to show that the young adult male immigrants were the most active class in sexual activity. Subgrouping form FAS was a ''space-segregation'' tactic of mating for the losers of both sexes in the competition. Some parameters of copulation were also documented.

PATTERNS OF SPATIAL-DISPERSION, LOCOMOTION AND FORAGING BEHAVIOR IN 3 GROUPS OF THE YUNNAN SNUB-NOSED LANGUR (RHINOPITHECUS-BIETI)

Aspects of the behaviour of three groups of Yunnan snub-nosed langurs, Rhinopithecus bieti, were observed over the course of three field seasons from 1986 to 1988. The major findings of the study were: (1) The habitats of R. bieti were mainly at heights of 3,600-4,150 m above sea level. (2) Groups were very large, with group sizes ranging from more than 100 to 269 individuals. (3) Spatial dispersion densities ranged from about 27 to 106 m2/individual during sleeping and resting, to feeding dispersions as large as 5,000-15,000 m2. (4) The locomotor repertoire of R. bieti consisted largely of walking, jumping and climbing. On very rare occasions, semibrachiation was observed, but true brachiation was never observed. The locomotor repertoires of juveniles were more diverse than those of subadults or adults. (5) Communication consisted mainly of eye-to-eye contact accompanied by murmurs; while loud calls were heard only rarely. (6) Groups moved between sleeping and feeding sites in single file. It is concluded that R. bieti is a mainly terrestrial species.

Differences between FRP bond behavior in cracked and uncracked regions

Based on an analysis of the experimental results of a proposed bond test method, significant differences are shown to exist between the local FRP bond stress-slip relationships in the uncracked anchorage regions and in the regions between cracks. The proposed method simulates the bond behavior between the flexural cracks and anchorage regions of a flexurally FRP-strengthened RC beam. The boundary conditions, including the presence of cracks and steel, are shown to have significant effects on the local bond stress-slip models. The results showed that, at the same force, the bond stresses in the regions between cracks were lower than in regions outside the cracks, so the debonding formed in the anchorage regions. The local bond stress-slip models in the anchorage regions can be obtained from the conventional bond test methods but these do not mimic the conditions between the cracks.

Sexual behavior in a one-male unit of Rhinopithecus bieti in captivity

Data regarding the sexual behavior of black-and-white snub-nosed monkeys (Rhinopithecus bieti) were collected in 1998 in a one-male unit in captivity by all-occurrences sampling during the mating season. Before the present study, little was known about the sexual behavior of this species. This study showed that female solicitation is mainly expressed as "prostration plus glancing laterally" (PG) or "sitting plus head moving up and down" (HM), and male solicitation is exhibited by the "grunt bared-teeth display." The mount-to-ejaculation ratio was 5.2 on average, and single-mount ejaculations (SMEs) were observed in only 4.4% of mounts on days with at least one ejaculation. Therefore, the main copulatory pattern of this species is multiple-mount ejaculation (MME). Females initiated 72% of 18 ejaculatory mounts. Females initiated more ejaculatory mounts than non-ejaculatory ones. In general, the patterns of sexual behavior in this species are similar to those reported for other Colobines. (C) 2004 Wiley-Liss, Inc.