Engineers' professional learning: a practice-theory perspective

With the increasing challenges facing professional engineers working in more complex, global and interdisciplinary contexts, different approaches to understanding how engineers practice and learn are necessary. This paper draws on recent research in the social sciences from the field of workplace learning, to suggest that a practice-theory perspective on engineers' professional learning is fruitful. It shifts the focus from the attributes of the individual learner (knowledge, skills and attitudes) to the attributes of the practice (interactions, materiality, opportunities and challenges). Learning is thus more than the technical acquisition and transfer of knowledge, but a complex bundle of activities, that is, social, material, embodied and emerging. The paper is illustrated with examples from a research study of the learning of experienced engineers in the construction industry to demonstrate common practices – site walks and design review meetings – in which learning takes place.

Effects of fibre parameters on the ultraviolet protection of fibre assemblies

Ultraviolet (UV) radiation protection is becoming increasingly necessary for human health, and textiles play an important role. The interaction between UV light and textiles is a complex one, involving fibre, yarn and fabric parameters. In this study, an optical model is presented for examining the influences of fibre parameters on the UV protection offered by a bundle of fibres with a given mass. The effects of mean fibre diameter and fibre type on UV absorption were examined. The model was verified with results of UV–visible diffuse reflectance measurements on natural and synthetic fibres. When the mass of fibres was kept constant, within the measurement range in this study, a bundle of fibres with coarser fibres had a lower UV reflectance than that with finer ones. The model accurately predicted factors influencing UV protection, including fibre diameter, fibre transmittance, porosity and refractive index.

UV protection performance of textiles affected by fiber cross-sectional shape

Abstract
In this study, a model was set up for simulating the effects of varying fiber cross-sectional shapes on ultraviolet protection of fibers. The fiber diameter and fiber type were also involved in the model setting. Experiments of diffuse reflectance spectra measurement on natural (wool, cotton, silk), regenerated (bamboo viscose) and synthetic (polyester, nylon) fibers were conducted to verify the model predicted results. When a more complex shape was assumed as the fiber cross-section for model calculation, the predicted results have a better agreement with the actual results. The effects on ultraviolet absorption from fibers with different cross-sectional shapes were investigated at a single fiber, fiber bundle and yarn levels. With the same material, when the fiber cross-sectional area and the areal coverage of a single fiber were constant, the triangular shape had the lowest ultraviolet transmittance and the highest ultraviolet reflectance for a single fiber and also for a fiber bundle. The difference of fiber cross-sectional shapes was also significant in the ultraviolet protection of a single yarn.

Weathering, fibre strength and colour properties of processed white cashmere

Weathering refers to the degradation of wool fibres that occur during growth from exposure of the fleece to sunlight, water and air. Weathering damage to Merino wool reduces quantities of fibre that are harvested, reduces length in both raw and processed wools, reduces spinning performance and dyeing outcomes. This work aimed to aimed to quantify if and to what extent weathering occurred in 38 lots of commercial dehaired white cashmere and cashmere top sourced from traditional and new origins of production and the extent of any association between weathering and tensile strength properties of the dehaired cashmere and cashmere top. The cashmere was tested for physical properties, bundle tenacity and extension, tristimulus values brightness (Y) and yellowness (Y-Z) and reflectance. Dye uptake was used as an index of weathering. Linear models, relating to weathering, bundle tenacity and Y-Z were fitted to origin and other objective measurements. Mean attributes (range) were: mean fibre diameter, 17.0 μm (13.5–21.3 μm); bundle tenacity of tops, 10.3 cN/tex (8.3–12.9 cN/tex), for dehaired fibre, 10.1 cN/tex (9.1–11.4 cN/tex). Stain uptake varied from 0.92 to 6.34 mg/g fibre indicating a six-fold variation in the extent of weathering. Both the extent of weathering and the bundle tenacity of commercial lots of cashmere were affected by the origin of the cashmere. Increased weathering reduced bundle tenacity, bundle extension, increased the yellowness and reduced reflectance of white cashmere. Bundle tenacity of cashmere declined as fibre diameter variability increased from 20 to 22.5%. For the samples tested, the cashmere from China, Mongolia, Afghanistan and Iran showed more weathering than cashmere from Australia, New Zealand and the USA. The differences in the extent of weathering and of bundle tenacity between cashmere from different origins were of commercial significance.

Organizational design as an enabler for innovation: evidence from a German Mechanical Engineering Company

Over the past two decades there has been a profusion of empirical studies of organizational design and its relationship to efficiency, productivity and flexibility of an organization. In parallel, there has been a wide range of studies about innovation management in different kind of industries and firms. However, with some exceptions, the organizational and innovation management bodies of literature tend to examine the issues of organizational design and innovation management individually, mainly in the context of large firms operating at the technological frontier. There seems to be a scarcity of empirical studies that bring together organizational design and innovation and examine them empirically and over time in the context of small and medium sized enterprises. This dissertation seeks to provide a small contribution in that direction. This dissertation examines the dynamic relationship between organizational design and innovation. This relationship is examined on the basis of a single-case design in a medium sized mechanical engineering company in Germany. The covered time period ranges from 1958 until 2009, although the actual focus falls on the recent past. This dissertation draws on first-hand qualitative empirical evidence gathered through extensive field work. The main findings are: 1. There is always a bundle of organizational dimensions which impacts innovation. These main organizational design dimensions are: (1) Strategy & Leadership, (2) Resources & Capabilities, (3) Structure, (4) Culture, (5) Networks & Partnerships, (6) Processes and (7) Knowledge Management. However, the importance of the different organizational design dimensions changes over time. While for example for the production of simple, standardized parts, a simple organizational design was appropriate, the company needed to have a more advanced organizational design in order to be able to produce customized, complex parts with high quality. Hence the technological maturity of a company is related to its organizational maturity. 2. The introduction of innovations of the analyzed company were highly dependent on organizational conditions which enabled their introduction. The results of the long term case study show, that some innovations would not have been introduced successfully if the organizational elements like for example training and qualification, the build of network and partnerships or the acquisition of appropriate resources and capabilities, were not in place. Hence it can be concluded, that organizational design is an enabling factor for innovation. These findings contribute to advance our understanding of the complex relationship between organizational design and innovation. This highlights the growing importance of a comprehensive, innovation stimulating organizational design of companies. The results suggest to managers that innovation is not only dependent on a single organizational factor but on the appropriate, comprehensive design of the organization. Hence manager should consider to review regularly the design of their organizations in order to maintain a innovation stimulating environment.

Synergies and price trends in sequential auctions

In this paper we consider sequential auctions where an individual’s value for a bundle of objects is either greater than the sum of the values for the objects separately (positive synergy) or less than the sum (negative synergy). We show that the existence of positive synergies implies declining expected prices. When synergies are negative, expected prices are increasing. There are several corollaries. First, the seller is indi¤erent between selling the objects simultaneously as a bundle or sequentially when synergies are positive. Second, when synergies are negative, the expected revenue generated by the simultaneous auction can be larger or smaller than the expected revenue generated by the sequential auction. In addition, in the presence of positive synergies, an option to buy the additional object at the price of the …rst object is never exercised in the symmetric equilibrium and the seller’s revenue is unchanged. Under negative synergies, in contrast, if there is an equilibrium where the option is never exercised, then equilibrium prices may either increase or decrease and, therefore, the net e¤ect on the seller’s revenue of the introduction of an option is ambiguous. Finally, we examine two special cases with asymmetric players. In the …rst case, players have distinct synergies. In this example, even if one player has positive synergies and the other has negative synergies, it is still possible for expected prices to decline. In the second case, one player wants two objects and the remaining players want one object each. For this example, we show that expected prices may not necessarily decrease as predicted by Branco (1997). The reason is that players with singleunit demand will generally bid less than their true valuations in the …rst period. Therefore, there are two opposing forces; the reduction in the bid of the player with multiple-demand in the last auction and less aggressive bidding in the …rst auction by the players with single-unit demand.

Three essays on local demand for public services

Local provision of public services has the positive effect of increasing the efficiency because each locality has its idiosyncrasies that determine a particular demand for public services. This dissertation addresses different aspects of the local demand for public goods and services and their relationship with political incentives. The text is divided in three essays. The first essay aims to test the existence of yardstick competition in education spending using panel data from Brazilian municipalities. The essay estimates two-regime spatial Durbin models with time and spatial fixed effects using maximum likelihood, where the regimes represent different electoral and educational accountability institutional settings. First, it is investigated whether the lame duck incumbents tend to engage in less strategic interaction as a result of the impossibility of reelection, which lowers the incentives for them to signal their type (good or bad) to the voters by mimicking their neighbors’ expenditures. Additionally, it is evaluated whether the lack of electorate support faced by the minority governments causes the incumbents to mimic the neighbors’ spending to a greater extent to increase their odds of reelection. Next, the essay estimates the effects of the institutional change introduced by the disclosure on April 2007 of the Basic Education Development Index (known as IDEB) and its goals on the strategic interaction at the municipality level. This institutional change potentially increased the incentives for incumbents to follow the national best practices in an attempt to signal their type to voters, thus reducing the importance of local information spillover. The same model is also tested using school inputs that are believed to improve students’ performance in place of education spending. The results show evidence for yardstick competition in education spending. Spatial auto-correlation is lower among the lame ducks and higher among the incumbents with minority support (a smaller vote margin). In addition, the institutional change introduced by the IDEB reduced the spatial interaction in education spending and input-setting, thus diminishing the importance of local information spillover. The second essay investigates the role played by the geographic distance between the poor and non-poor in the local demand for income redistribution. In particular, the study provides an empirical test of the geographically limited altruism model proposed in Pauly (1973), incorporating the possibility of participation costs associated with the provision of transfers (Van de Wale, 1998). First, the discussion is motivated by allowing for an “iceberg cost” of participation in the programs for the poor individuals in Pauly’s original model. Next, using data from the 2000 Brazilian Census and a panel of municipalities based on the National Household Sample Survey (PNAD) from 2001 to 2007, all the distance-related explanatory variables indicate that an increased proximity between poor and non-poor is associated with better targeting of the programs (demand for redistribution). For instance, a 1-hour increase in the time spent commuting by the poor reduces the targeting by 3.158 percentage points. This result is similar to that of Ashworth, Heyndels and Smolders (2002) but is definitely not due to the program leakages. To empirically disentangle participation costs and spatially restricted altruism effects, an additional test is conducted using unique panel data based on the 2004 and 2006 PNAD, which assess the number of benefits and the average benefit value received by beneficiaries. The estimates suggest that both cost and altruism play important roles in targeting determination in Brazil, and thus, in the determination of the demand for redistribution. Lastly, the results indicate that ‘size matters’; i.e., the budget for redistribution has a positive impact on targeting. The third essay aims to empirically test the validity of the median voter model for the Brazilian case. Information on municipalities are obtained from the Population Census and the Brazilian Supreme Electoral Court for the year 2000. First, the median voter demand for local public services is estimated. The bundles of services offered by reelection candidates are identified as the expenditures realized during incumbents’ first term in office. The assumption of perfect information of candidates concerning the median demand is relaxed and a weaker hypothesis, of rational expectation, is imposed. Thus, incumbents make mistakes about the median demand that are referred to as misperception errors. Thus, at a given point in time, incumbents can provide a bundle (given by the amount of expenditures per capita) that differs from median voter’s demand for public services by a multiplicative error term, which is included in the residuals of the demand equation. Next, it is estimated the impact of the module of this misperception error on the electoral performance of incumbents using a selection models. The result suggests that the median voter model is valid for the case of Brazilian municipalities.

Morfologia de frutos, sementes e plântulas de castanheira (Terminalia catappa L. - COMBRETACEAE)

O trabalho foi realizado com o objetivo de descrever morfologicamente os frutos, sementes e plântulas de castanheira. Foi feita a biometria dos frutos e das sementes e sua caracterização quanto à forma, por meio de mensurações com paquímetro e observações realizadas em estereomicroscópio com câmara clara. Os frutos de castanheira são carnosos, indeiscentes, do tipo nucóide, glabros, de coloração verde a vinácea, projeção das nervuras carpelares externamente evidentes, com epicarpo delgado, mesocarpo carnoso e esponjoso de coloração vinácea, com feixes vasculares conspícuos em corte transversal. Geralmente, cada fruto contém apenas uma semente. As sementes são exalbuminosas, de formas alongadas e cilíndricas, recobertas por endocarpo rígido de coloração marrom; possuem cerca de 2,5cm, 0,7cm e 0,7cm, de comprimento, largura e espessura, respectivamente. A germinação das sementes de castanheira é epígea, e a plantula é fanerocotiledonar.

Clinical characterization of chronic chagasic cardiomyopathy in dogs

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Degradação in vitro de tecidos da lâmina foliar e do colmo de gramíneas forrageiras tropicais, em função do estádio de desenvolvimento

O experimento foi realizado com o objetivo de avaliar o efeito da idade sobre o potencial de degradação dos diferentes tecidos da lâmina foliar e do colmo de capim-braquiária (Brachiaria decumbens), capim-gordura (Melinis minutiflora) e capim-tifton 85 (Cynodon sp). Foram amostradas a 7ª (capim-braquiária e capim-gordura) e a 11ª (capim-tifton 85) lâminas foliares, no dia da exposição da lígula e 20 dias após. Por meio de observações ao microscópio foram estimadas a extensão da digestão in vitro dos tecidos da lâmina e do colmo e a redução na espessura da parede de células do esclerênquima do colmo. Lâminas foliares e segmentos de colmos jovens apresentaram maiores áreas digeridas. Permaneceram intactos os tecidos com células de parede espessada e lignificada, a bainha parenquimática dos feixes, o esclerênquima, o xilema e a epiderme do colmo. Tecidos com células de parede delgada, normalmente não-lignificada, o mesofilo, o floema e o parênquima, desapareceram completamente. O avanço na idade reduziu a digestão do mesofilo, em lâminas de capim-braquiária e capim-gordura, e do parênquima em colmos, principalmente de capim-gordura. A epiderme na lâmina foliar foi parcialmente digerida, independentemente da idade e da espécie. Embora aparentemente intactas, células esclerenquimáticas do colmo sofreram redução da espessura da parede com a incubação em líquido ruminal. A porcentagem de redução variou de 7 a 37% e a taxa de redução da espessura de 0,007 a 0,018 µm/h.

Características anatômicas da lâmina foliar e do colmo de gramíneas forrageiras tropicais, em função do nível de inserção no perfilho, da idade e da estação de crescimento

Foram avaliados os efeitos da idade, do nível de inserção da folha no perfilho e da estação de crescimento (verão ou outono), sobre a proporção de tecidos e a espessura da parede celular em lâminas foliares e segmentos de colmo de capim-braquiária (Brachiaria decumbens), capim-gordura (Melinis minutiflora) e capim-tifton 85 (Cynodon sp). Lâminas foliares das posições inferior e superior do perfilho foram colhidas no dia da exposição da lígula e 20 dias após. Foram determinadas as proporções relativas de epiderme, xilema, floema, bainha parenquimática dos feixes, esclerênquima, parênquima no colmo e mesofilo na lâmina foliar. Foram medidas as espessuras das paredes dos vasos de metaxilema e do esclerênquima da lâmina e do colmo. A proporção de tecidos em lâminas foliares não foi alterada pela idade nem pela estação de crescimento, sendo a espessura da parede de células do esclerênquima da lâmina a única característica modificada pela idade. Lâminas do nível de inserção superior apresentaram mais elevadas proporções de esclerênquima, bainha parenquimática dos feixes e xilema e células do esclerênquima e do metaxilema com paredes mais espessas, enquanto as lâminas do nível de inserção inferior se destacaram por apresentar mais elevada proporção de mesofilo e paredes celulares mais delgadas. Enquanto a proporção de parênquima decresceu, a área relativa de esclerênquima e as espessuras das paredes celulares variaram diretamente com a idade do colmo e foram maiores, em geral, no verão.

Modelo 2,5D de predição de propagação para ambientes interiores utilizando o método do traçado de raios

A 2.5D ray-tracing propagation model is proposed to predict radio loss in indoor environment. Specifically, we opted for the Shooting and Bouncing Rays (SBR) method, together with the Geometrieal Theory of Diffrartion (GTD). Besides the line-of-sight propagation (LOS), we consider that the radio waves may experience reflection, refraction, and diffraction (NLOS). In the Shooting and Bouncing Rays (SBR) method, the transmitter antenna launches a bundle of rays that may or may not reach the receiver. Considering the transmitting antenna as a point, the rays will start to launch from this position and can reach the receiver either directly or after reflections, refractions, diffractions, or even after any combination of the previous effects. To model the environment, a database is built to record geometrical characteristics and information on the constituent materials of the scenario. The database works independently of the simulation program, allowing robustness and flexibility to model other seenarios. Each propagation mechanism is treated separately. In line-of-sight propagation, the main contribution to the received signal comes from the direct ray, while reflected, refracted, and diffracted signal dominate when the line-of-sight is blocked. For this case, the transmitted signal reaches the receiver through more than one path, resulting in a multipath fading. The transmitting channel of a mobile system is simulated by moving either the transmitter or the receiver around the environment. The validity of the method is verified through simulations and measurements. The computed path losses are compared with the measured values at 1.8 GHz ftequency. The results were obtained for the main corridor and room classes adjacent to it. A reasonable agreement is observed. The numerical predictions are also compared with published data at 900 MHz and 2.44 GHz frequencies showing good convergence

Fototriangulação com parâmetros adicionais para câmaras digitais: uma avaliação experimental

Considering the growing use of digital cameras in Photogrammetric projects, especially in aerial survey, this paper presents tests and analyses of bundle block adjustment with additional parameters, using different mathematical models, and blocks of images acquired by the SAAPI digital acquisition system. Three blocks of images were processed by the LPS (Leica Photogrammetry Suite) software, in which five groups of additional parameters (AP) can be used: Bauer, Jacobsen, Ebner, Brown and Lens distortion. These AP's models were employed in the bundle block adjustment, and the results were analyzed based on the accuracy of the checking points and on the changes in these additional parameters. The obtained results showed that the Lens Distortion model allowed the best results.

A influência das injunções de orientação relativa na calibração de um sistema dual de câmeras digitais

Image acquisition systems based on multi-head arrangement of digital frame cameras, such as the commercial systems DMC, UltraCam, besides others, are attractive alternatives enabling larger imaging area when compared to a single frame camera. Considering that in these systems, cameras are tightly attached to an external mount, it is assumed that relative position and orientation between cameras are stable during image acquisition and, consequently, these constraint can be included in the calibration step. This constraint is acceptable because estimates of the relative orientation (RO) parameters between cameras, from previously estimated exterior orientation parameters, present higher and significant deviations than the expected physical variations, due to error propagation. In order to solve this problem, this work presents an approach based on simultaneous calibration of two or more cameras using constraints that state that the relative rotation matrix and the distance between the cameras head are stable. Experiments with images acquired by an arrangement of two Hasselblad H2D cameras were accomplished, without and with the mentioned constraints. The experiments showed that the calibration process with RO constraints allows better results than the approach based on single camera calibration, provided that the estimation has included only images with good target distribution.

A Model for Bundled Conductors considering a Non-Homogeneous Distribution of the Current through Subconductors

This paper describes an alternative procedure to obtain an equivalent conductor from a bundled conductor, taking into account the distribution of the current in subcondutors of the bundle. Firstly, it is introduced a brief background about the concept of Geometric Mean Radius (GMR) and how this methodology is applied to define an equivalent conductor and its electric parameters. Emphasizing that the classical procedure, using GMR, is limited to premise which the current is equally distributed through subconductors. Afterwards, it is described the development of proposed method and applications for an equivalent conductor obtained from a conventional transmission line bundled conductor and from an equivalent conductor based on a bundle with compressed SF(6) insulation system, where the current is unequally distributed through subconductors.