A manufacturing planning and control system for a flexible manufacturing system

A flexible manufacturing system (FMS) can offer important advantages in terms of more efficient production, shorter throughput times, lower stocks and a higher quality of work. To realize these advantages, a well designed manufacturing planning and control system (MPCS) is a key condition. In practical cases, these planning and control systems are often based on a hierarchical structure. This paper discusses the most relevant characteristics of such a hierarchical MPCS and, by using a practical case, describes possible solutions to a variety of subproblems

Struggling with solutions:A case study of using organisation concepts

International audienceEngineers contribute to the constant flow of allegedly new tools and organisation concepts. These tend to be presented as solutions to existing organisational problems. These solutions may become problems themselves, however. We present a longitudinal case of how a truck manufacturer struggled with various similar and dissimilar concepts in realizing organisational changes. Whilst it may seem idiosyncratic, the company's struggles are probably typical for organisational change praxis. Reflecting on the case, we present a model to help practitioners reflect on their use of concepts and tools (thereby arguably contributing to the issue we signal)

Rheological and Microstructural Changes of Oat and Barley Starches During Heating and Cooling

Microstructural and rheological changes in barley and oat starch dispersions during heating and cooling were studied by light microscopy and dynamic viscoelastic measurements. The two starch pastes showed similar viscoelastic properties after gelatinization, but during cooling the 20% barley starch pastes heated at 95°C underwent a sharp transition in viscoelastic behaviour probably due to the gelation of amylose. This transition was shifted to lower temperatures at 10% starch concentration. Microstructural studies of an 8% barley starch dispersion heated to 90°C using the smear technique showed amylose to form a network structure around the granules. The granules in starch paste heated to 95°C were poorly stained and amylopectin was fragmented. Microscopic examination of an embedded section of the cooled barley starch gel showed amylose to form a continuous phase in which starch granules were dispersed. G\u27 increased below 80°C during cooling of 10% oat starch dispersions preheated at 95 °C. No rheological changes occurred when they were preheated at only 90°C. Microstructural studies of an 8% oat starch dispersion heated to 90°C using the smear technique showed amylose to form a network structure around the granules. Part of the granule structure had already broken down. Heating to 95°C induced considerable changes in the granule structure of oat starch gels. Amylopectin formed a very fine network. Microscopic examination of embedded sections of the cooled, stored gel showed a much coarser structure compared with that of the smear

Warming, euxinia and sea level rise during the Paleocene–Eocene Thermal Maximum on the Gulf Coastal Plain: implications for ocean oxygenation and nutrient cycling

The Paleocene–Eocene Thermal Maximum(PETM, ?56 Ma) was a ?200 kyr episode of globalwarming, associated with massive injections of 13C-depletedcarbon into the ocean–atmosphere system. Although climatechange during the PETM is relatively well constrained,effects on marine oxygen concentrations and nutrientcycling remain largely unclear. We identify the PETM in asediment core from the US margin of the Gulf of Mexico.Biomarker-based paleotemperature proxies (methylationof branched tetraether–cyclization of branched tetraether(MBT–CBT) and TEX86) indicate that continental air andsea surface temperatures warmed from 27–29 to ?35 ?C,although variations in the relative abundances of terrestrialand marine biomarkers may have influenced these estimates.Vegetation changes, as recorded from pollen assemblages,support this warming.The PETM is bracketed by two unconformities. It overliesPaleocene silt- and mudstones and is rich in angular(thus in situ produced; autochthonous) glauconite grains,which indicate sedimentary condensation. A drop in the relativeabundance of terrestrial organic matter and changesin the dinoflagellate cyst assemblages suggest that risingsea level shifted the deposition of terrigenous material landward.This is consistent with previous findings of eustatic sealevel rise during the PETM. Regionally, the attribution of theglauconite-rich unit to the PETM implicates the dating of aprimate fossil, argued to represent the oldest North Americanspecimen on record.The biomarker isorenieratene within the PETM indicatesthat euxinic photic zone conditions developed, likely seasonally,along the Gulf Coastal Plain. A global data compilationindicates that O2 concentrations dropped in allocean basins in response to warming, hydrological change,and carbon cycle feedbacks. This culminated in (seasonal)anoxia along many continental margins, analogous to moderntrends. Seafloor deoxygenation and widespread (seasonal)anoxia likely caused phosphorus regeneration fromsuboxic and anoxic sediments.We argue that this fueled shelfeutrophication, as widely recorded from microfossil studies,increasing organic carbon burial along many continentalPublished by Copernicus Publications on behalf of the European Geosciences Union.Warming, euxinia and sea level rise during the PETMmargins as a negative feedback to carbon input and globalwarming. If properly quantified with future work, the PETMoffers the opportunity to assess the biogeochemical effects ofenhanced phosphorus regeneration, as well as the timescaleson which this feedback operates in view of modern and futureocean deoxygenation

Efficacy of natural antimicrobials in toothpaste formulations against oral biofilms in vitro

AbstractObjectivesTo evaluate the antimicrobial efficacies of two toothpaste formulations containing natural antimicrobials (herbal extracts and chitosan) against oral biofilms of different composition and maturational status.MethodsBacteria from a buffer suspension or fresh saliva were adhered for 2h to a salivary conditioning film and subsequently grown for 16h. Dual-species biofilms were prepared from Actinomyces naeslundii T14V-J1 and Streptococcus oralis J22, whilst multi-species biofilms were grown from freshly collected human saliva. Biofilms were exposed to 25wt% toothpaste supernatants. A chlorhexidine-containing mouthrinse and a buffer were used as positive- and negative-controls, respectively. Antibacterial efficacy was concluded from acute killing, bacterial removal, prevention of bacterial re-deposition and continued killing during re-deposition.ResultsThe herbal- and chitosan-based supernatants showed immediate killing of oral biofilm bacteria, comparable with chlorhexidine. Moreover, exposure of a biofilm to these supernatants or chlorhexidine, yielded ongoing killing of biofilm bacteria after exposure during re-deposition of bacteria to a matured 16h biofilm, but not to a much thinner initial biofilm formed by 2h adhesion only. This suggests that thicker, more matured biofilms can absorb and release oral antimicrobials.ConclusionsSupernatants based on herbal- and chitosan-based toothpastes have comparable immediate and ongoing antibacterial efficacies as chlorhexidine. Natural antimicrobials and chlorhexidine absorb in oral biofilms which contributes to their substantive action