Lead time chain

Oxidation. AH polyamides are susceptible to oxidation. This involves the initial formation of a free radical on the carbon alpha to the NH group, which reacts to form a peroxy radical with subsequent chain reactions leading to chain scission and yellowing. As soon as molten nylon is exposed to air it starts to discolor and continues to oxidize until it is cooled to below 60°C. It is important, therefore, to minimize the exposure of hot nylon to air to avoid discoloration or loss of molecular weight. Similarly, nylon parts exposed to high temperature in air lose their properties with time as a result of oxidation. This process can be minimized by using material containing stabilizer additives. 

In the effort to make pure blue-emitting materials Shim and coworkers [146] synthesized a series of PPV-based copolymers containing carbazole (polymers 95 and 96) and fluorene (polymers 97 and 98) units via Wittig polycondensation. The use of trimethylsilyl substituents, instead of alkoxy groups, eliminates the electron donor influence of the latter and leads to chain distortion that bathochromically shifts the emission (Amax = 480 nm for 95 and 495 nm for 97). In addition, a very high PLQY was found for these polymers in the solid state (64 and 81%, respectively). Single-layer PLEDs fabricated with 95 and 97 (ITO/polymer/Al) showed EL efficiencies of 13 and 32 times higher than MEH-PPV, respectively (see also Ref. [147] for synthesis and PLED studies of polymers 99 and 100) (Chart 2.20). 

Customer order schedules need to be integrated with deliveries, production orders and procurement orders. Volumes and values are already defined. Therefore, the focus is on a time schedule of orders considering production and distribution lead times. Fig. 21 illustrates the main task in value chain operations also now focused on a geographical region such as Europe. The individual schedules of sales orders and purchase orders have to be integrated with distribution and production schedules. 

The relaxation variables focus on the front-end of the value chain in sales and distribution excluding production and procurement due to the commodity value chain characteristics with long production lead times and less flexibility in the backend. Of course, it is possible to have relaxation variables for all constraints and areas of the value chain. However, this would lead to higher complexity for the planner as well as longer solution times with more integer variables. Therefore, relaxation is kept limited. 

Besides, products in a global multi-stage network can have a lead time caused by transportation or inventory ranges until they are used in the subsequent steps. This lead time has to be considered when calculating future inventory values of products in the value chain network a raw material product procured at a certain price can require several periods, until it is included in a final product sold in distant markets. Therefore, the inventory value change related to the procured raw material is effective certain periods after the raw material has been procured. 

In order to reflect these lead times, the concept of a timestamp is introduced. Timestamp is used in computer science documenting the system time when a certain event or transaction occurs e.g. for logging events (N.N. 2007). In the context of future inventory value planning, the time-stamp marks the period, when the first raw material has reached a certain stage in the value chain network included into a specific product. In the example illustrated in fig. 57, the raw material is processed in the same period to be converted into product 1. Therefore, all four value chain steps indexed from one to four occur in the same period and have the same time-stamp one. Conversion into product 2, however, requires additional time caused by production lead times, safety inventory and/or transportation time, that the steps indexed with five and six have a time stamp of two. The timestamp reflects that the inventory value of product 2 is not based on the raw material costs from the same period but based on the raw material costs from the previous period in order to reflect the lead time. Consequently, value chain indices and timestamps are defined for all steps and can cover multiple periods reflecting that raw materials in a global complex multi-stage value chain network can take several months, until they are sold as part of a finished product to the market. 

Finally, the timestamp rf , / p,l e Ivcl is defined to indicate the average lead time measured in planning periods compared to the first raw material initialized with timestamp 1. Increase of the timestamp is caused by transportation e.g. between different continents, holding inventories or the further production processing in the value chain. 

The raw material product value shown in the foreground of the chart is related to the procurement price offers. Subsequently, the following products are listed based on the raw material. The production step costs for each product are the values-added on the raw material value. In addition, an assumed timestamp is considered reflecting lead times of products through the value chain therefore, price changes of the raw material would impact the value of e.g. product E with some periods of delay. 

Boeken P, Kotlik L (2001) Optimierung der Supply Chain in der pharmazeuti-schen Industrie, A.D. Little (ed.) Einkauf - Produktion - Logistik, pp 67-74 Bogataj M, Bogataj L (2004) On the compact presentation of the lead times perturbations in distribution networks. International Journal of Production Economics 88 145-155... 

The stereo-regularity of a polymer can be reduced by a variety of defects. For example, regio-errors arise when a 2,1-monomer insertion occurs instead of a 1,2-in-sertion the latter is usually 10 -10 times faster. Misinsertions can lead to chain termination and formation of butenyl end groups, they can be incorporated into... 

The only way to avoid this is by strict analysis of the supply chain from the customer order to final product delivery. Definition of the optimized (theoretical) process and sequential work towards a high service level approach allow the identification of gaps, and of opportunities which might not always be the cheapest (ship versus train versus plane) but could be the most effective way to reduce capital costs and shorten planning scope - an important aspect, especially in volatile customer markets with long production processes on the (chemical) supplier side. As in the case of CIP, this needs clear parameters, KPIs, commitment from all players, and regular tracking. The most important parameters are the lead time for all products, optimal lot sizes, replenishment points, and safety inventories. 

Figure 22.5 shows how product, customer, and market characteristics can determine different SCM strategies and design implications. For example, the strategic choice to serve niche customers with high price specialty chemicals is only tenable if the high-value inventory is centralized to reduce costs, and if a fast, responsive supply chain is set up to fill customer orders within the requested lead time from central inventory. 

The time taken to travel along the innovation chain (see Figure DIO), known as the lead-time, can vary from several months in speciality chemical companies to many years in pharmaceutical companies. This wide variation can, in part, be explained by... 

As described in Section 1.1, the goal of the simulation study is to quantify the relationships between the simulation outputs and the inputs or factors. For this case study, the outputs are the steady-state mean costs of the whole supply chain (discussed in Section 3.2) and the inputs are factors such as lead-time, quality, operation time of an individual process, and number of resources. Our ultimate goal (as reported by Kleijnen et al., 2003) is to find robust solutions for the supply chain problem. Thus we distinguish between two types of factors ... 

Spliting in any of the indicated ways leads to chain propagation. In non-polar media, free ions only exist for a short time during bond rearrangement. Thus the silanolate group, rather than a silanolate anion, should be regarded as the active centre [320]. Therefore we have proposed a scheme respecting this circumstance ... 

The above phenomenological description of the viscoelastic behaviour of polymer melts and concentrated solutions leads to the following important conclusions if one focuses on the behavioiu- in the terminal region of relaxation, what is usually done for temperature (time-temperature equivalence) may also be done for the concentration effects and the effects of chain length one may define a "time-chain length equivalence" and "time-concentration equivalence"[4]. For monodisperse species, the various shifts along the vertical (modulus) axis and horizontal (time or frequency axis) are contained in two reducing parameters the... 

At the same time photoreaction of acetyl alkyl radicals (reaction 3 in scheme 3), leading to chain process of acetic acid formation, indicates the proceeding of Norrish reaction of the 2" type. 

At present, the sector is lacking the infrastructure for the manufacture of antibodies to come. Despite major investments however, the high demands and long lead times prohibit a short-term solution other than a significant increase in overall productivity to close the current gaps in bio-pharmaceutical supply chains. 

The lure of parametric release to commercial organizations is undoubtably monetary, either as reduced inventory costs or as reduced lead times within the supply chain. The cost balancing this out is better process control. From the standpoints of quality, sterility assurance, and responsibility to the recipient of the sterile product, the loss of a wholly inadequate end-product test is a low price to pay for more attention being given to the process characteristics that really influence sterility. 

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