Parts verification for multi-level-dependent demand manufacturing systems: a recognition and classification structure

This research has developed and implemented a part recognition and classification structure to execute parts verification in a multi-level-dependent demand manufacturing system. The part-recognition algorithm enables the parent and child relationship between parts to be recognised in a finite-capacitated manufacturing system. This algorithm was developed using the SIMAN simulation language and implemented in a multi-level-dependent demand manufacturing simulation model. The part-classification structure enables the modelling of a multi-level-dependent demand manufacturing system between parts to be carried out effectively. The part-classification structure was programmed using Visual Basic Application (VBA) and was integrated into the work-to-list generated from a simulated materials requirements planning (MRP) model. This part-classification structure was then implemented in the multi-level-dependent demand manufacturing simulation model. Two stages of implementation, namely, parameterisation and execution, of the part recognition and classification structure were carried out. A real case study was used and five detailed steps of execution were processed. Simulation experiments and MRP were run to verify and validate the part recognition and classification structure. The results led to the conclusion that implementation of the recognition and classification structure has effectively verified the correct parts and sub-assemblies used for the correct product and order. No parts nor sub-assembly shortages were found, and the quantity required was produced. The scheduled release for some orders was delayed due to overload of the required resources. When the loading is normal, all scheduled release timing is adhered to. The recognition and classification structure has a robust design; hence, it can be easily adapted to new system parameters to study different or more complex cases.     

The effects of accumulated timing jitter on some sine wavemeasurements

This paper investigates the effects of accumulated timing jitter on the signal-to-noise ratio (SNR) and on the phase angle measurement of real sine waves. These measurements are done via the Fast Fourier Transform (FFT) method. Accumulated timing jitter occurs when the sine wave is sampled by an unstable clock where the clock periods are randomly changing. Also, accumulated jitter is a problem in ramp-type bases that were often used in sampling oscilloscopes. Expressions for an estimate of the signal-to-noise ratio [SNR_(est.)] and phase variance in terms of the jitter distribution parameters and the number of FFT points (N) are derived. The derived expressions are verified through computer simulations. Finally, a comparison between independent and accumulated jitter is presented     

Fatal air embolism: a complication of manipulation of a cavitating metastatic lesion of the liver

The use of NMR spectroscopy in combinatorial chemistry has provided a versatile tool for monitoring combinatorial chemistry reactions and for assessing ligand-receptor interactions. The application of magic angle spinning NMR is widespread and has allowed structure determination to be performed on compounds attached to solid supports. A variety of two-dimensional NMR techniques have been applied to enhance the usability of the magic angle spinning NMR data. New developments for solution NMR analysis include high performance liquid chromatography, NMR, mass spectroscopy and flow NMR. NMR based methods currently being investigated may prove valuable as compound screening tools.     

Toward the development of a standard e‐readiness assessment policy

Information networking for digital integration is becoming of increasing importance for national and international organizations concerned with development. E‐Readiness assessments, for various countries, are associated with the investigation of their state of readiness for such integration. They help in understanding the problems that need to be resolved in order to avoid digital divide, or even digital isolation, from world development. Such assessments lack standard policies, which provide unified measures that ease evaluations, support analysis and comparisons, and help in diagnosing problems and deriving solutions. This paper is concerned with the development of a standard e‐readiness assessment policy. It provides a base for the development of such a policy, and hopes that this base will contribute to a future standard international policy. Copyright © 2003 John Wiley & Sons, Ltd.     

Crude liver membrane fractions and extracellular matrix components as substrata regulate differentially the preservation and inducibility of cytochrome P-450 isoenzymes in cultured rat hepatocytes

The influence of cell-substrata interactions on the preservation of basal or in-vivo-induced microsomal cytochrome P-450 isoenzyme contents in cultured rat hepatocytes and on the adaptive responses after exposure to phenobarbital or 3-methylcholanthrene in vitro, was investigated. Hepatocytes from untreated or phenobarbital-treated rats were cultured in serum-free, aprotinin-supplemented culture medium in 96-well microtiter plates coated with collagen type I (COL), laminin, fibronectin or crude liver membrane fractions/collagen type I (CMF/COL). Basal cell functions were characterized by measuring the total protein content and lactate dehydrogenase release. The relative contributions of CYP1A1/2, CYP2B1/2, CYP2C6, CYP2C11, CYP3A and CYP4A isoenzymes were determined with ELISA using monoclonal antibodies raised against purified cytochromes P-450 from rat liver microsomes. The characterization of the CMF revealed that contaminations with mitochondria, nuclei and lysosomes are relatively low. Among these, membranes derived from the endoplasmic reticulum appeared to be the major organelle contaminant of the CMF. The matrix components laminin, fibronectin and collagen type IV were found in appreciable amounts. Hepatocytes from untreated rats, cultured for up to nine days on CMF/COL-coated plates, retained their relative cytochrome P-450 contents at 1.5-3-fold higher levels when compared to cells cultured on COL, fibronectin or laminin. Similarly, hepatocytes from phenobarbital-treated rats preserved the contents of barbiturate-inducible CYP2B1/2 and CYP3A proteins best when cultured on CMF/COL. After exposure of hepatocytes cultured on CMF/COL to phenobarbital from days 3-6, CYP3A proteins were enhanced more than twofold and CYP2B1/2, depending on the exposure level, increased 1.3-6-fold. After exposure to 3-methylcholanthrene, a threefold increase of CYP1A proteins was found in CMF/COL and laminin cultures. These results indicate that CMF/COL, as a substratum in rat hepatocyte cultures, regulates gene expression of cytochromes P-450 isoenzymes for up to 9 days and provides a matrix which enables the cells to respond qualitatively similar to the response observed in different zones of the liver. This activity cannot be replaced by single-matrix components.     

Effect of high temperatures on the dielectric behaviour of viscose fibres at low frequency

Commercial and purified viscose fibres exhibit dielectric dispersion and a loss peak within the frequency range 0.05–1 k c/s and at temperatures of 80–140°C. Such high temperature relaxation is local in nature and is attributed to side group motion. The characteristics of the absorption bands of these samples are compared and the results obtained are interpreted. The variation of the dielectric constant with temperature showed a second order transition at about 110°C with these samples, which disappears on hydrolysis.     

Dielectric relaxation of monoesters based poly(styrene-co-maleic anhydride) copolymer

A series of alkyl-grafted copolymers based on styrene-maleic anhydride (SMA) copolymers were synthesized by esterification of SMA with several long chain normal aliphatic alcohols. The prepared copolymers were characterized by FT-IR and ¹H NMR and DSC. The dielectric behavior of these copolymers was investigated in the frequency 20–10⁵ Hz and temperature −40 to 180 °C ranges. Two relaxation processes were observed, α, and β-relaxation. The former is associated with the glass-rubber transition and is characterized by the Vogel–Fulcher–Tammann temperature dependence and the latter relaxation is related to the local motion of the ester side groups attached to the polymer backbone. The apparent activation energy for the β-relaxation was found to depend significantly on the alkyl chain length. The dielectric analysis of the β-relaxation process detected is discussed.