Temporal relations between mineral deposits and global tectonic cycles

Natural Environment Research Council (grant NE/J021822/1) supported this research.Mineral deposits are heterogeneously distributed in both space and time, with variations reflecting tectonic setting, evolving environmental conditions, as in the atmosphere and hydrosphere, and secular changes in the Earth’s thermal history. The distribution of deposit types whose settings are tied to plate margin processes (e.g. orogenic gold, volcanic-hosted massive sulphide, Mississippi valley type Pb–Zn deposits) correlates well with the supercontinent cycle, whereas deposits related to intra-cratonic settings and mantle-driven igneous events, such as Ni–Cu–PGE deposits, lack a clear association. The episodic distribution of deposits tied to the supercontinent cycle is accentuated by selective preservation and biasing of rock units and events during supercontinent assembly, a process that encases the deposit within the assembled supercontinent and isolates it from subsequent removal and recycling at plate margins.Publisher PD

An integrated approach for remanufacturing job shop scheduling with routing alternatives.

Remanufacturing is a practice of growing importance due to increasing environmental awareness and regulations. However, the stochastic natures inherent in the remanufacturing processes complicate its scheduling. This paper undertakes the challenge and presents a remanufacturing job shop scheduling approach by integrating alternative routing assignment and machine resource dispatching. A colored timed Petri net is introduced to model the dynamics of remanufacturing process, such as various process routings, uncertain operation times for cores, and machine resource conflicts. With the color attributes in Petri nets, two types of decision points, recovery routing selection and resource dispatching, are introduced and linked with places in CTPN model. With time attributes in Petri nets, the temporal aspect of recovery operations for cores as well as the evolution dynamics in cores\u27 operational stages is mathematically analyzed. A hybrid meta-heuristic algorithm embedded scheduling strategy over CTPN is proposed to search for the optimal recovery routings for worn cores and their recovery operation sequences on workstations, in minimizing the total production cost. The approach is demonstrated through the remanufacturing of used machine tool and its effectiveness is compared against another two cases: baseline case with fixed recovery process routings and case 2 using standard SA/MST

Collector Managed Inventory, A Proactive Planning Approach to the Collection of Liquids coming from End-of-life Vehicles

In this article we introduce Collector Managed Inventory (CMI) as the reverse logistics counter part of Vendor Managed Inventory (VMI).The collection company takes responsibility for the inventories of cores or materials to be recycled.Experience in forward supply chain management has shown the potential of VMI by bringing the coordination of transportation and inventory decisions to the same supply chain entity.Using information technology called telemetry, we are able to monitor inventory levels at distance.We introduce a proactive planning methodology based on two types of collection orders: must- and can-orders.Every collection period all must-orders have to be collected, while canorders are only collected if they can be combined beneficially with the must-orders.The routing problem is solved by a combination of route generation and set partitioning.The system is illustrated in a real-life case study for Auto Recycling Nederland on the collection of liquids coming from end-oflife vehicles, such as coolant and oil.In several scenarios the old reactive approach is compared to the proactive approach resulting in cost savings up to about 19%.supply;logistics;vehicle routine;distribution;information technology;inventory

Hydrodynamic simulations of the triaxial bulge of M31

The interstellar gas flow in the inner disk of M31 is modelled using a new, two dimensional, grid based, hydrodynamics code. The potential of the stellar bulge is derived from its surface brightness profile. The bulge is assumed to be triaxial and rotating in the same plane as the disk in order to explain the twisted nature of M31's central isophotes and the non circular gas velocities in the inner disk. Results are compared with CO observations and the bulge is found to be a fast rotator with a B-band mass-to-light ratio, Y = 6.5 +/- 0.8, and a ratio of co-rotation radius to bulge semi-major axis, R = 1.2 +/- 0.1, implying that any dark halo must have a low density core in contradiction to the predictions of CDM. These conclusions would be strengthened by further observations confirming the model's off axis CO velocity predictions.Comment: 11 pages, 9 figures, Accepted for A+

Processes Affecting the Behavior of Redox-Sensitive Elements in Chesapeake Bay

Several processes can affect variations in the chemical composition of an estuary, including (1) biogeochemical reactions in the water column, (2) advective transport, and (3) diffusion from underlying sediments. The purpose of the study was to establish whether estuarine redox reactions are controlled by a complex interaction of processes 1 to 3. Short-term and long-term studies were conducted in Chesapeake Bay. Redox species involved in redox cycling include oxygen, iron, manganese, hydrogen sulfide, nitrogen species, arsenic and antimony species, while phosphate is indirectly involved in redox cycles. Silicate was used as a non-redox tracer. For the short-term study, a Lagrangian drifter was used to track a parcel of bottom water, and thus allow monitoring of in situ water column processes and sediment-water exchange. In addition, a fixed (Eulerian) station was established to integrate processes 1 to 3. Seasonal changes in porewater and water column profiles were used to calculate fluxes and establish the coupling between benthic inputs and the inventory of redox sensitive chemical species in bottom waters of the Bay. Estuarine modeling was used on the long-term data sets from the upper Bay to estimate riverine and estuarine fluxes. During summer, there was estuarine flux (internal production) for ammonia, phosphate, iron, manganese, and silicate. A comparison of these estuarine fluxes and benthic fluxes from cores taken in the upper Bay showed that the total flux of materials produced within this portion of the estuary is strongly influenced by sediment-water exchange, particularly for ammonia and phosphate. Benthic flux of silicate was a more important contribution to the estuarine flux of silicate in summer. The mechanistic details of the coupling of the transport and in situ biogeochemical processes were closely examined by the short-term study. At the fixed station, large hourly variations in the concentration of redox species indicate that advection controls Eulerian behavior. From the Lagrangian study, maximum concentrations usually occurred when the water mass passed over areas with higher benthic fluxes. Overall, the concentration of redox sensitive chemical species were controlled by in situ reactions and benthic sources, but the variability in concentration at a fixed point was primarily due to advection

Collector Managed Inventory, A Proactive Planning Approach to the Collection of Liquids coming from End-of-life Vehicles

In this article we introduce Collector Managed Inventory (CMI) as the reverse logistics counter part of Vendor Managed Inventory (VMI).The collection company takes responsibility for the inventories of cores or materials to be recycled.Experience in forward supply chain management has shown the potential of VMI by bringing the coordination of transportation and inventory decisions to the same supply chain entity.Using information technology called telemetry, we are able to monitor inventory levels at distance.We introduce a proactive planning methodology based on two types of collection orders: must- and can-orders.Every collection period all must-orders have to be collected, while canorders are only collected if they can be combined beneficially with the must-orders.The routing problem is solved by a combination of route generation and set partitioning.The system is illustrated in a real-life case study for Auto Recycling Nederland on the collection of liquids coming from end-oflife vehicles, such as coolant and oil.In several scenarios the old reactive approach is compared to the proactive approach resulting in cost savings up to about 19%.

Towards a simulation-based understanding of smart remanufacturing operations : a comparative analysis

While the majority of literature on remanufacturing operations examines an end-of-life (EOL) strategy which is both manual and mechanised, authors generally agree that digitalisation of remanufacturing is expected to increase in the next decade. Subsequently, a new research area described as digitally-enabled remanufacturing, remanufacturing 4.0 or smart remanufacturing is emerging. This is an automated, data-driven system of remanufacturing by means of Industry 4.0 (I4.0) paradigms. Insights into smart remanufacturing can be provided through simulation modelling of the remanufacturing process. While the use of simulation modelling in order to predict responses and behaviour is prevalent in remanufacturing, the use of these tools in smart remanufacturing is still limited in literature. The goal of this research is to present, as a first of its kind, a comparative understanding of simulation modelling in remanufacturing in order to suggest the ideal modelling tool for smart remanufacturing. The proposed comparison includes system dynamics, discrete event simulation and agent based modelling techniques. We apply these modelling techniques on a smart remanufacturing space of a sensor-enabled product and use assumptions derived from industry experts. We then proceed to model the remanufacturing operation from sorting and inspection of cores to final inspection of the remanufactured product. Through our analysis of the assumptions utilised and simulation modelling results we conclude that, while individual modelling techniques present important strategic and operational insights, their individual use may not be sufficient to offer comprehensive knowledge to remanufacturers due to the challenge of data complexity that smart remanufacturing offers

Cleaner production for environmental conscious manufacturing in the foundry industry

The purpose of the paper is to illustrate application of the cleaner production concept so as to incorporate environmental protection into business performance. The study analyses areas pertaining to the foundry industry that impact negatively on the environment leading to unsustainable resource utilisation and suggests options for promoting sustainable development within the industry, with specific focus on a foundry in a lower income country (LIC)