A decomposition method for multi-product kanban systems with setup times and lost sales

We consider kanban controlled production systems with three or more different products processed on a single manufacturing facility. Customers for a product arrive according to a Poisson process. If a customer's demand cannot be met from stock, the customer leaves and satisfies his demand elsewhere (lost sales). Between the production of different products setup changes must be performed that take a significant time. Setup times and processing times are product-specific and follow exponential distributions. A production run continues until the target inventory level given by the number of kanbans for the product has been reached (exhaustive processing). Then the manufacturing facility is set up for the next product according to a fixed setup cycle. The exact model is mathematically intractable even for smaller systems. Therefore, we propose a decomposition-based approximation method for estimating steady-state performance measures     

Polydimethylsiloxane based polyurethane and its composite with layered double hydroxide: Synthesis and its thermal properties

This investigation reports the synthesis of a new class of polyurethane (PU) based on bis(hydroxyalkyl) polydimethylsiloxane (PDMS) as diol and isophorone diisocyanate as diisocyanate followed by the preparation of PU/layered double hydroxide (PU/LDH) nanocomposite via ex-situ technique. Nuclear magnetic resonance and Fourier-transform infrared spectroscopy studies confirm the formation of PU and incorporation of PDMS into the PU backbone. Thermogravimetry analysis revealed that thermal stability of the composite improves significantly with incorporation of LDH into the PU matrix. This may be accredited to the barrier effect rendered by the LDH layers. Differential scanning calorimetry study reveals that with the incorporation of LDH, glass transition temperature (T_g) of the composite increases for an optimum level of loading beyond which it remains constant.     

Potent inhibitors of the human UDP-glucuronosyltransferase 2B7 derived from the sesquiterpenoid alcohol longifolol

The tricyclic sesquiterpenol (+)-longifolol served as a lead structure for the design of inhibitors of the human UDP-glucuronosyltransferase (UGT) 2B7. Twenty-four homochiral and epimeric longifolol derivatives were synthesized and screened for their ability to inhibit the enzyme. The absolute configuration at the stereogenic center C1' was determined by X-ray crystallography and 2D NMR spectroscopy (gHSQC, gNOESY). The phenyl-substituted secondary alcohol 16 b (beta-phenyllongifolol) displayed the highest affinity toward UGT2B7, and its inhibitory dissociation constant was 0.91 nM. The mode of inhibition was rapidly reversible and competitive. The inhibitor was not glucuronidated by UGT2B7 or other hepatic UGTs, presumably as a result of the high steric demand exerted by the phenyl group. Inhibition assays employing 14 other UGT isoforms suggested that inhibitor 16 b was highly selective for UGT2B7.     

Capacitively coupled transmission line pulsing cc-TLP––a traceable and reproducible stress method in the CDM-domain

This paper describes a new test method called capacitively coupled transmission line pulsing cc-TLP. It is applied to different test circuits which were mounted on specially designed package emulators with a defined background capacitance. The test results are compared with the ESD thresholds obtained by CDM tests. The cc-TLP results correlate well with the CDM data.     

Mathematics 1868�C2008: a bibliometric analysis

This paper presents a bibliometric analysis of the literature published in the field of mathematics from 1868 to date. The data originate from the Zentralblatt MATH database. The increase rate of publications per year reflects the growth of the mathematics community and both can well be represented by exponential or linear functions, the latter especially after the Second World War. The distribution of publications follows Bradford??s law but in contrast to many other disciplines there is no strong domination of a small number of journals. The productivity of authors follows two inverse power laws of the Lotka form with different parameters, one in the range of low productivity and the other in the range of high productivity. The average productivity has changed only slightly since the year 1870. As far as multiple authorship is concerned the distribution of the number of authors per publication can be described quite well by a Gamma Distribution. The average number of authors per publication has been increasing steadily; while it was close to 1 up to the first quarter of the last century it has now reached a value of 2 in the last few years. This means that the percentage of single-authored papers has fallen from over 95% in the years before 1930 to about 30% today.     

Automatisierte Mikrobild-Analyse zur Klassifizierung von Eisenerz für die Roheisenherstellung

The mineralogical composition and structural properties of iron ores control their behaviour in industrial reduction plants. Micro-images of polished sections are processed by the software VisuMet to determine the proportions of limonite, hematite and magnetite. From the mineralogical composition and the structural properties of iron ores VisuMet assesses their reduction properties at standard reduction conditions.     

高性能透明尼龙材料在眼镜中的应用

眼镜的发展史，在某种程度上说，也就是新材料、新技术的发展史，正是由于新材料、新技术的不断涌现和改进，才推动了眼镜制造工艺的不断提高。     

Limits of FET modelling by lumped elements

Common lumped-element FET modelling is compared with the equivalent distributed-element formulation. The deviations are studied and the validity range of such lumped-element models is shown.