Availability constraints

Availability constraints the macroscopic limits on material resources and the availability or up-time of equipment. Availability of raw materials is an obvious constraint at scheduling. Obviously, no catalytic hydrogenation can be done if the catalyst is unavailable. Simultaneous operation of certain tasks is restricted by the limited availability of common utilities such as steam, electricity, or labour. The priority sequence in a product chain needs to be respected by ensuring that intermediate products are manufactured in time to be available when required by a batch of the consecutive product. 

Abstract. We recall the emergence of the 3He problem , its currently accepted solution, and we summarize the presently available constraints on models of stellar nucleosynthesis and studies of Galactic chemical evolution from observations of the He isotopic ratio in the Galaxy. 

The major capacity limitations as well as the availability constraints are shown in Table 7.1. Raw materials, product prices, and demand uncertainty were assumed to... 

Most non-chondrule solids in the inner Solar System experienced thermal processing (see Chapter 8) that could have modified their initial oxygen isotopic composition (Yurimoto Kuramoto 2004). The complicated structure of meteoritic oxygen isotopes is difficult to reproduce simply by physical mixing of different reservoirs. Apart from thermal processing (e.g. melting, vaporization, condensation), a large mass-independent chemical process is required. The exact mechanism for this likely photochemical process is yet unknown, but the available constraints leave only a few pathways open. 

Gehrtng, C. M. Denich, M. Kanashiro, and P. L. G. Vlek. 1999- Response of secondary vegetation in Eastern Amazonia to relaxed nutrient availability constraints. Biogeochemistry 456) 223-241. 

As discussed by Coogan et al. (2002), there are currently two classes of models for the formation of the gabbroic sequence that are, to first order, consistent with available constraints from marine seismic investigations, and structural and petrologic studies of gabbros in ophiolites and oceanic drill cores. In the first class of models (Figure 25(a)), crystallization occurs... 

In a posteriori treatment, only the availability constraints are considered. An available key population is defined. It indudes the experimental compounds most resembling the themetical key ones. Thus, the avaOable key population in this study includes 11 of the... 

Following is a review of available constraints on noble gas isotope distributions and fluxes. There are no expected or observed relevant variations in Kr. For further discussion of the data, see Graham (2002) and Hilton et al. (2002) in this volume. 

While some objections can be overcome with model modifications, it must be concluded that the fundamental mechanism of this model, generation of atmospheric and MORE noble gas characteristics by progressive extraction of the atmosphere from the upper mantle as presently sampled by MORE, cannot account for many of the available constraints, especially those from Ne and Xe isotopes. 

Is the core a plausible reservoir These calculations indicate that, using presently available constraints, the core remains a plausible source of the He found in OIB. Measured high He/" He ratios would then be the result of mixtures of He from the core that has a solar nebula He/" He ratio with radiogenic " He from the mantle. However, the implications for other geochemical parameters also must be considered. Other elements that would be affected by bulk transfer of core material into the mantle include the Pt-group elements and volatiles that may be relatively abundant in the core, such as H and C. While some limits on the amount of transferred core material are provided by these (Porcelli and Halliday 2001), it should be noted that the amount needed to sustain the He flux is still very uncertain, and it is possible that upward revisions in the amount of noble gases within the early Earth, or in the metal/silicate partition coefficients, could reduce the required flux of core material by an order of magnitude or more. 

The order-promising process employed partitions the due date time horizon into three intervals fixed product, flexible product and flexible resource. For the fixed product interval, which spans from approximately the present time to two weeks into the future, resources, in the form of manufacturing orders (MO) are fixed. An MO specifies the production quantity for each product at each assembly line in each factory. That is, a fixed production schedule is set, which takes into account both production capacity availability and critical material availability. Having a fixed schedule stabilizes production dynamics in the near term and allows for the required materials to be set up and put in place. Any order commitments made for this time interval must fit within the fixed production schedule. In the flexible product interval, two kinds of resources, capacity and material, are considered. The capacity consists of both production capacity in different factories and transportation capacity from factories to sales subsidiaries. The production capacity is given daily at factory level in terms of machine-hour and manpower availability, while the transportation capacity is specified as weekly maximum quantity from factories to sales subsidiaries. The weekly availability of individual critical materials is aggregated into finished good level availability grouped based on the bill of material (BoM). Any order commitments made for this time interval must satisfy the capacity and material availability constraints. The flexible product interval spans from approximately two weeks to two months into the future. For the flexible resource interval, which covers due dates more than two months into the future, the only constraint considered is production capacity. This interval starts beyond the resource lead times so any resource commitments can be met. 

When distance geometry is applied to NMR data, the metric matrix equations can be solved repeatedly giving an ensemble of conformations (Figure 13) that satisfies the available constraints as well as possible. All these conformations are equally realistic as far as the experimental NMR data go. The predicted molecular geometries can be subjected to further energy minimization refinement with or without distance constraints. 

For noncritical raw materials, only broad marketwide information is assumed to be available during the design phase. Therefore, the total quantity of each noncritical raw material purchased and shipped to all plants must be less than or equal to the overall market availability of each noncritical raw material during each period. Hence, the noncritical raw material availability constraints are expressed as... 

Note that this constraint also constitutes an availability constraint for the CSD. Indeed, context is necessary for the nominal operation of the card. 

Attempting to measure all 45 socio-economic indicators in any given post-disaster context is the desirable objective, but data availability constraints mean this is not always feasible. Quite often multiple sources of data are required to measure all indicators (e.g., reinsurance companies such as MiinichRe or SwissRe, international organization situation reports such as produced from the United Nations Office for the Coordination of Humanitarian Affairs (OCHA) or the International Federation of Red Cross and Red Crescent Societies (IFRC), Post-Disaster Needs Assessment (PDNA) case studies, such as the ones conducted by the World Bank (WB)). Consequently, this may lead to slight variations exist in estimates and totals. 

A.S.Carrie and D.T.S.Perera, Work Scheduling in FMS Under Tool Availability Constraint,IJPR, V24, 6(1986) 1299-1308. 

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