Using pull and flow systems to improve production stability in real estate development projects

Objectives: The objective of this thesis is to understand the effects of the application of flow-based management systems on medium-size sites (€2-50 million work turnover) made by medium-sized companies (20-200 employees). The purpose of this research is to develop and evaluate a pull scheduling system based on the Last Planner™ System (LPS) to improve production flow stability of real estate developments made by SMEs. The research investigates the application of pull systems from manufacturing industries and those that have not been fully tested in the construction industry. Method: A three-block real estate development project in Brussels was used to ground the context where action research was chosen to initiate the research. Action research follows an ascending spiral that consists of 4 phases described in 1991 by Zuber-Skerrit: 1) planning, 2) acting, 3) observing and 4) reflecting. Once the first circle is initiated, the four activities lead to the next cycle. The reflections phase of circle (n) then leads to the planning phase of circle (n+1). These loops can be derived indefinitely or at least while the research has not met its objectives. Passing from action to critical reflection and back and vice versa in a cyclical process helps build a wider view and a greater understanding. In this context, three action circles were conducted. In this way, the methods, data and interpretation were continuously refined (Dick, 2002). The sequential development of the three blocks made by the same teams eased the process of capturing insights from a phase and building an optimal scheduling process. A lack of works planning, and progress understanding was found to be a major issue when the research started on the ongoing works of the first block. 5S and LPS were tested as a means of improving construction works planning at both the physical and managerial levels. The application of the first three Ss (sort, set, shine) yielded an impact on respect for the work site but were not sufficient to significantly affect the planning. The application of the first two steps of the LPS (master planning, phase planning and make ready) showed improvement but were also limited in their impact in the search for planning reliability. On-site measurements showed that despite a high percentage plan completion (PPC) score in the LPS, analysis of the progress of each apartment showed high volatility from one 23 / 408 week to the next. This volatility came from a lack of visibility in the scheduling system. Although the progress of each week was determined by what was and should have been done based on the LPS, more structure in the scheduling system and more reliability in the forecasts of the works were needed to increase the works stability. Given that takt time has been successfully used in the manufacturing industry to address variability in the demand, and that significant similarities exist between a construction site and a manufacturing line, it was decided to test this as a complement to the LPS in the research action taken on the second block of the building development. Encouraging results were measured, and on-site work in this block was improved. Findings: it was found that the discipline needed to respect the system, the rules and sequence of the work demanded high-level and constant surveillance from site management. In the long run, this could put the whole system at risk. In order to be as efficient, sustainable and duplicable as possible, the scheduling system should be visual, need no interpretation and lead works in a pull flow. Manufacturing has successfully used a simple but efficient system named kanban to achieve level production and ensure a fully pulled system in a variable demand environment while limiting the sources of errors. The third block proved that such a method can work in conjunction with takt time and LPS and improve the works stability by favouring a self-pull system. Impact: following the scheduling system developed by the action circles in Block 2, there has been a reduction of nearly 20% of the lead time measured and a significant increase in quality (the number of snagging works decreased by 95%). Therefore, the stress on the site management team decreased (captured by interviews). The early findings and encouraging results are signs of the importance of the research undertaken. Limitations: The research has been conducted on traditional sites regarding typology, size, techniques, management structure, and contractors, so the findings are addressed to a wide audience across the construction industry. The limitation of the research comes from the domain of the construction observed: real estate in Belgium. Although it is highly probable that the issues detected on site by the research and the mechanisms used to address those issues are duplicable in other domains of the construction industry, there is, at this point of the research, no clear evidence

Sensorimotor signals underlying space perception: An investigation based on self-touch

Perception of space has puzzled scientists since antiquity, and is among the foundational questions of scientific psychology. Classical “local sign” theories assert that perception of spatial extent ultimately derives from efferent signals specifying the intensity of motor commands. Everyday cases of self-touch, such as stroking the left forearm with the right index fingertip, provide an important platform for studying spatial perception, because of the tight correlation between motor and tactile extents. Nevertheless, if the motor and sensory information in self-touch were artificially decoupled, these classical theories would clearly predict that motor signals – especially if self-generated rather than passive – should influence spatial perceptual judgements, but not vice versa. We tested this hypothesis by quantifying the contribution of tactile, kinaesthetic, and motor information to judgements of spatial extent. In a self-touch paradigm involving two coupled robots in master-slave configuration, voluntary movements of the right-hand produced simultaneous tactile stroking on the left forearm. Crucially, the coupling between robots was manipulated so that tactile stimulation could be shorter, equal, or longer in extent than the movement that caused it. Participants judged either the extent of the movement, or the extent of the tactile stroke. By controlling sensorimotor gains in this way, we quantified how motor signals influence tactile spatial perception, and vice versa. Perception of tactile extent was strongly biased by the amplitude of the movement performed. Importantly, touch also affected the perceived extent of movement. Finally, the effect of movement on touch was significantly stronger when movements were actively-generated compared to when the participant's right hand was passively moved by the experimenter. Overall, these results suggest that motor signals indeed dominate the construction of spatial percepts, at least when the normal tight correlation between motor and sensory signals is broken. Importantly, however, this dominance is not total, as classical theory might suggest

Strontium ranelate improves bone strength in ovariectomized rat by positively influencing bone resistance determinants

Summary: Treatment of adult ovariectomized (OVX) rats with strontium ranelate prevented vertebral biomechanics degradation as a result of the prevention of bone loss and micro-architecture deterioration associated to an effect on intrinsic bone material quality. Strontium ranelate influenced the determinants of bone strength by prevention of ovariectomy-induced changes which contribute to explain strontium ranelate antifracture efficacy. Introduction: Strontium ranelate effects on the determinants of bone strength in OVX rats were evaluated. Methods: Adult female Sprague-Dawley rats were OVX, then treated daily for 52weeks with 125, 250, or 625mg strontium ranelate/kg. Bone strength, mass, micro-architecture, turnover, and intrinsic quality were assessed. Results: Strontium ranelate prevented ovariectomy-induced deterioration in mechanical properties with energy necessary for fracture completely maintained vs. SHAM at 625mg/kg/day, which corresponds to the clinical dose. This was related to a dose-dependent effect on bone volume, higher trabeculae number, and lower trabecular separation in strontium ranelate vs. OVX. Load and energy required to induce lamella deformation were higher with strontium ranelate than in OVX and in SHAM, indicating that the bone formed with strontium ranelate is able to withstand greater damage before fracture. Bone formation was maintained high or even increased in strontium ranelate as shown by mineralizing surfaces and alkaline phosphatase while strontium ranelate led to reductions in deoxypyridinoline. Conclusion: Strontium ranelate administered at 625mg/kg/day for 52weeks prevented OVX-induced biomechanical properties deterioration by influencing the determinants of bone strength: it prevented bone loss and micro-architecture degradation in association with an effect on intrinsic bone quality. These beneficial effects on bone contribute to explain strontium ranelate antifracture efficac

Dynamic Displacement Vector Interacts with Tactile Localization

Locating a tactile stimulus on the body seems effortless and straightforward. However, the perceived location of a tactile stimulation can differ from its physical location [1, 2, 3]. Tactile mislocalizations can depend on the timing of successive stimulations [2, 4, 5], tactile motion mechanisms [6], or processes that “remap” stimuli from skin locations to external space coordinates [7, 8, 9, 10, 11]. We report six experiments demonstrating that the perception of tactile localization on a static body part is strongly affected by the displacement between the locations of two successive task-irrelevant actions. Participants moved their index finger between two keys. Each keypress triggered synchronous tactile stimulation at a randomized location on the immobilized wrist or forehead. Participants reported the location of the second tactile stimulation relative to the first. The direction of either active finger movements or passive finger displacements biased participants’ tactile orientation judgements (experiment 1). The effect generalized to tactile stimuli delivered to other body sites (experiment 2). Two successive keypresses, by different fingers at distinct locations, reproduced the effect (experiment 3). The effect remained even when the hand that moved was placed far from the tactile stimulation site (experiments 4 and 5). Temporal synchrony within 600 ms between the movement and tactile stimulations was necessary for the effect (experiment 6). Our results indicate that a dynamic displacement vector, defined as the location of one sensorimotor event relative to the one before, plays a strong role in structuring tactile spatial perception

Place et rôle du riz pluvial dans les systèmes de production du lac Alaotra Les systèmes SCV (semis direct sur couverture végétale permanente) : une alternative viable pour une agriculture pluviale durable

La région de l'Alaotra repose sur un plateau situé à 750 mètres d'altitude avec au cœur de la plaine le lac Alaotra. La surface cultivée en riziculture est estimée à 148 500 ha en 2000 (FAO/UPDR, 2000), dont 75-80 000 ha dans la cuvette du Lac et plus de 65-70 000 ha au sud et dans les zones en périphérie, qui constitue 10% de la surface rizicole nationale pour seulement 4% des riziculteurs malgaches. Cette région réalise 33% de la valeur ajoutée de l'ensemble de la filière nationale et 15% de la richesse générée par le secteur riz. Le climat irrégulier constitue une contrainte majeure pour tous les agriculteurs du lac Alaotra. Les relations agriculture-élevage sont au cœur de la problématique de développement et d'évolution des exploitations agricoles.Ainsi, avec la saturation des rizières irrigables ou à Mauvaise Maîtrise de l'Eau (RMME), la colonisation agricole des tanety anciennement dévolus aux pâturages extensifs depuis les années 1980 s'est accélérer, induisant la perturbation des activités d'élevage bovin traditionnel extensif à objectif de capitalisation qui évoluent aujourd'hui vers un élevage productif (embouche et production laitière) ou de trait. Le diagnostic réalisé en 2007 a mis en évidence 7 types d'exploitations agricoles différents. Les différents systèmes de riziculture pluviale se retrouvent sur les plateaux sommitaux et les pentes des collines (en rotation jachère culture sur les sols très pauvres), les bas de pente et les baiboho, en rotation avec d'autres cultures pluviales (maïs, manioc, pois de terre...) avec ou sans jachère, ou en système SCV depuis leur introduction au début des années 2000. L'introduction de variétés composites poly-aptitudes de type Sebota a pu lever une contrainte majeure des zones ni totalement irriguées ni totalement pluviales mais intermédiaires dans les RMME (riziculture pluviale partiellement irriguée, selon l'accès à l'eau et les caractéristiques climatiques de la saison), Les systèmes SCV mis au point sur baiboho avec des successions culturales de type riz de saison / haricot de contre saison - maïs de saison ou riz de saison puis vesce de contre saison associée ou non à des cultures maraîchères montrent également un niveau de production et de sécurité par rapport aux aléas climatiques très proche voire supérieurs à ceux obtenus en riziculture irriguée. La part du riz pluvial dans la formation du revenu et la sécurité alimentaire a été analysée pour chaque type d'exploitation et varie de 20 à 30 % du revenu riz total (avant autoconsommation), et se révèle croissante en fonction du rapport tanety / rizière dans l'exploitation. Ainsi, sur certaines zones, le riz pluvial semble avoir de beaux jours devant lui

Parallax and Kinematics of PSR B0919+06 from VLBA Astrometry and Interstellar Scintillometry

Results are presented from a long-term astrometry program on PSR B0919+06 using the NRAO Very Long Baseline Array. With ten observations (seven epochs) between 1994--2000, we measure a proper motion of 18.35 +/- 0.06 mas/yr in RA, 86.56 +/- 0.12 mas/yr in Dec, and a parallax of 0.83 +/- 0.13 mas (68% confidence intervals). This yields a pulsar distance of 1.21 +/- 0.19 kpc, making PSR B0919+06 the farthest pulsar for which a trigonometric parallax has been obtained, and the implied pulsar transverse speed is 505 +/- 80 km/s. Combining the distance estimate with interstellar scintillation data spanning 20 years, we infer the existence of a patchy or clumpy scattering screen along the line of sight in addition to the distributed electron density predicted by models for the Galaxy, and constrain the location of this scattering region to within about 250 parsecs of the Sun. Comparison with the lines of sight towards other pulsars in the same quadrant of the Galaxy permits refinement of our knowledge of the local interstellar matter in this direction.Comment: 12 pages, includes 4 figures and 3 tables, uses AASTeX 5 (included); ApJ submitte

Interhemispheric communication during haptic self-perception

During the haptic exploration of a planar surface, slight resistances against the hand's movement are illusorily perceived as asperities (bumps) in the surface. If the surface being touched is one's own skin, an actual bump would also produce increased tactile pressure from the moving finger onto the skin. We investigated how kinaesthetic and tactile signals combine to produce haptic perceptions during self-touch. Participants performed two successive movements with the right hand. A haptic force-control robot applied resistances to both movements, and participants judged which movement was felt to contain the larger bump. An additional robot delivered simultaneous but task-irrelevant tactile stroking to the left forearm. These strokes contained either increased or decreased tactile pressure synchronized with the resistance-induced illusory bump encountered by the right hand. We found that the size of bumps perceived by the right hand was enhanced by an increase in left tactile pressure, but also by a decrease. Tactile event detection was thus transferred interhemispherically, but the sign of the tactile information was not respected. Randomizing (rather than blocking) the presentation order of left tactile stimuli abolished these interhemispheric enhancement effects. Thus, interhemispheric transfer during bimanual self-touch requires a stable model of temporally synchronized events, but does not require geometric consistency between hemispheric information, nor between tactile and kinaesthetic representations of a single common object

The political economy of the Jospin government

This article explores the political economy of the French Socialist Party (PS), beginning with the neo-liberal U-turn of 1983. It then charts the re-evaluation of the PS's political economic foundations after the 1993 defeat, the rejection of the neo-liberal 'pensée unique', and the rehabilitation of a broadly Keynesian frame of reference. The article goes on to explore how this shift has fed through into the Jospin government's policy and positions at both the national and international level. It explores aspirations to reinvent the EU as a Keynesian social democratic 'policy space', and at the national level, employment, macroeconomic, and structural policies

Microstructure of the Local Interstellar Cloud and the Identification of the Hyades Cloud

We analyze high-resolution UV spectra of the Mg II h and k lines for 18 members of the Hyades Cluster to study inhomogeneity along these proximate lines of sight. The observations were taken by the Space Telescope Imaging Spectrograph (STIS) instrument on board the Hubble Space Telescope (HST). Three distinct velocity components are observed. All 18 lines of sight show absorption by the Local Interstellar Cloud (LIC), ten stars show absorption by an additional cloud, which we name the Hyades Cloud, and one star exhibits a third absorption component. The LIC absorption is observed at a lower radial velocity than predicted by the LIC velocity vector derived by Lallement & Bertin (1992) and Lallement et al. (1995), (v(predicted LIC) - v(observed LIC) = 2.9 +/- 0.7 km/s), which may indicate a compression or deceleration at the leading edge of the LIC. We propose an extention of the Hyades Cloud boundary based on previous HST observations of other stars in the general vicinity of the Hyades, as well as ground-based Ca II observations. We present our fits of the interstellar parameters for each absorption component. The availability of 18 similar lines of sight provides an excellent opportunity to study the inhomogeneity of the warm, partially ionized local interstellar medium (LISM). We find that these structures are roughly homogeneous. The measured Mg II column densities do not vary by more than a factor of 2 for angular separations of < 8 degrees, which at the outer edge of the LIC correspond to physical separations of < 0.6 pc.Comment: 35 pages, 11 figures, AASTEX v.5.0 plus EPSF extensions in mkfig.sty; accepted by Ap