This paper focuses on scheduling a rotary injection molding machine with dependent processing times. The injection machine has n pairs of positions to process n pairs of shoes. It is rotated after every cycle time. Cycle time is the maximum injection time of the jobs currently loaded in the machine. Thus, for all practical purposes, the processing time of a job depends on the combination of the jobs currently assigned to the machine. The uncertainty of processing time makes this problem more complicated than traditional parallel machine scheduling problems. Additionally, since switching jobs leads to mold changes, set-up time is also included in the analysis. We develop a Sequential Genetic Algorithm (SGA) to identify the best schedule with regard to makespan. In this approach, multiple GA evolvers are connected by using a feeding strategy, where each GA evolver identifies the best schedule with minimum makespan for the corresponding product family. A multi-segment (product lines) chromosome representation is applied to represent the product line sequence as well as the job sequence within a product family. Furthermore, an adaptive feeding strategy is also proposed to improve results and reduce computation times. Besides SGA, we also improve the performance of a traditional heuristic procedure by proposing a minimum ΔIT heuristic approach. The experimentation is performed by using four experimental data sets with different demand patterns and nine data sets from a shoe manufacturing plant. The results indicate that our SGA provides better schedule with respect to makespan value, while heuristic procedures take insignificant time to obtain results. Another observation is that adaptive feeding strategy helps to find good results in a shorter time. 相似文献
Microneedles are small needle‐like structures that are almost invisible to the naked eye. They have an immense potential to serve as a valuable tool in many medical applications, such as painless vaccination. Microneedles work by breaking through the stratum corneum, the outermost barrier layer of the skin, and providing a direct path for drug delivery into the skin. A lot of research has been presented over the past two decades on the applications of microneedles, yet the fundamental mechanism of how they interact, pressure, and penetrate the skin in its native state is worth examining further. As such, a major difficulty with understanding the mechanism of microneedle–skin interaction is the lack of an artificial mechanical human skin model to use as a standardized substrate. In this research news, the development of an artificial mechanical skin model based on a thorough mechanical study of fresh human and porcine skin samples is presented. The artificial mechanical skin model can be used to study the mechanical interactions between microneedles and skin, but not diffusion of molecules across skin. This model can assist in improving the performance of microneedles by enhancing the reproducibility of microneedle depth insertions for optimal drug delivery and biosensing.
Bromate formation from the reaction between chlorine and bromide in homogeneous solution is a slow process. The present study investigated metal oxides enhanced bromate formation during chlorination of bromide-containing waters. Selected metal oxides enhanced the decay of hypobromous acid (HOBr), a requisite intermediate during the oxidation of bromide to bromate, via (i) disproportionation to bromate in the presence of nickel oxide (NiO) and cupric oxide (CuO), (ii) oxidation of a metal to a higher valence state in the presence of cuprous oxide (Cu2O) and (iii) oxygen formation by NiO and CuO. Goethite (α-FeOOH) did not enhance either of these pathways. Non-charged species of metal oxides seem to be responsible for the catalytic disproportionation which shows its highest rate in the pH range near the pKa of HOBr. Due to the ability to catalyze HOBr disproportionation, bromate was formed during chlorination of bromide-containing waters in the presence of CuO and NiO, whereas no bromate was detected in the presence of Cu2O and α-FeOOH for analogous conditions. The inhibition ability of coexisting anions on bromate formation at pH 8.6 follows the sequence of phosphate >> sulfate > bicarbonate/carbonate. A black deposit in a water pipe harvested from a drinking water distribution system exerted significant residual oxidant decay and bromate formation during chlorination of bromide-containing waters. Energy dispersive spectroscopy (EDS) analyses showed that the black deposit contained copper (14%, atomic percentage) and nickel (1.8%, atomic percentage). Cupric oxide was further confirmed by X-ray diffraction (XRD). These results indicate that bromate formation may be of concern during chlorination of bromide-containing waters in distribution systems containing CuO and/or NiO. 相似文献
A new regulated utility interactive inverter for direct photovoltaic energy feedback to the mains has been realized. A modulated buck converter converts the photovoltaic dc current to a rectified 50-Hz sine wave current, and the following self-commutated half-bridge generates a 50-Hz sine wave current, which is fed into one phase of the public power grid. This nonclassical inverter needs only three power transistor switches and isolates the grid and the photovoltaic array using a commercial 50-Hz transformer. It acts as a current source, and due to pulsewidth modulation its output is a sine wave current with very low total harmonic distortion of one percent. The overall efficiency of the 1-kW prototype is at least 88 percent between 250 and 1000 W, and the projected efficiency is over 90 percent for 1-20 kW. Furthermore, a circuit which tracks the maximum power available from the photovoltaic generator has been developed. This circuit regulates the input power to its maximum by detecting the phase angle between the voltage and power ripples at the inverter input. 相似文献
Zusammenfassung Die isoelektrische Fokussierung einer wasserlöslichen Proteinfraktion von Hart- und Weichweizen aus Teigwarenprodukten wird mit der bisher üblichen disk-elektrophoretischen Trennmethode verglichen. Die Elektrofokussierung liefert im Gegensatz zur Disk-Elektrophorese auch bei Anwesenheit von Ei-Proteinen sowie nach vorgängiger Hitzedenaturierung der Proteine zuverlässige und genaue Resultate. Im weiteren wird zur besseren Auftrennung und Charakterisierung der wasserlöslichen Proteinfraktion eine zweidimensionale Trennmethode (isoelektrische Fokussierung und anschließende Elektrophorese) beschrieben.
Isoelectric focusing and two-dimensional separation of watersoluble protein fraction of hard and soft wheat from macaroni
Summary The isoelectric focusing of water-soluble protein fraction of hard and soft wheat from macaroni are compared with the disc electrophoresic separation methods. Electrofocusing produced more trustworthy and exacter results in the presence of egg proteins as well for heat-denaturated proteins. Further is described a better separation and characterisation of a water-soluble protein fraction using a two-dimensional system involving isoelectric focusing in the first dimension followed by electrophoresis in the second.
The ability to monitor several parameters simultaneously from distinct individual fluorescent reporter molecules facilitates the disentanglement of complex and interacting systems and opens new perspectives in areas from basic science to biopharmaceutical technology. By combining annular illumination microscopy, time-correlated single-photon counting, and multichannel detection, we were able to determine 14 independent parameters from one individual fluorophore. The whole set of parameters was deduced from the few properties of the fluorescence photons, i.e., arrival time, wavelength, and polarization. With this approach, the intensity, the polarization, and the spectral dynamics can be analyzed on a nanosecond time scale and the mean values can be monitored with submillisecond time resolution. Nanosecond spectral dynamics of single molecules has been observed, to the best of our knowledge, for the first time. From our experience, we can determine all parameters for more than 30% of the illuminated fluorophores in biological samples and for more than 80% in doped polymeric films. 相似文献
We have designed a multimodality system that combines optical coherence tomography (OCT) and laser-induced fluorescence (LIF) in a 2.0-mm-diameter endoscopic package. OCT provides approximately 18-microm resolution cross-sectional structural information over a 6-mm field. LIF spectra are collected sequentially at submillimeter resolution across the same field and provide histochemical information about the tissue. We present the use of a rod prism to reduce the asymmetry in the OCT beam caused by a cylindrical window. The endoscope has been applied to investigate mouse colon cancer in vivo. 相似文献