A framework for capacity planning and machine configuration in flexible assembly systems

We consider the problem of simultaneously determining the number of machines (and/or workers), the assignment of tasks (and related tools and components) to these machines, and the number of jobs circulating in a flexible assembly system (FAS), to satisfy steady-state throughput requirements for a family of similar products at minimum cost. We focus on situations where there are precedence relations among the various tasks, as is common in assembly systems. We present a framework for solving this problem based on a heuristic decomposition approach which involves the solution of only a few types of sub-problems. We demonstrate the efficiency and effectiveness of the overall procedure using a number of example problems.     

In-Situ Observation of SiC Bulk Single Crystal Growth by XRD System

In-situ analysis for SiC bulk single crystal growth was reported using vertical X-ray diffractometer system. A furnace for SiC sublimation growth combined with the XRD system which possessed three kinds of functions including topography, rocking curve measurement and crystal growth rate monitoring was developed. These functions could contribute as a powerful tool finding the optimum growth condition by dynamic observation in the crucible. In this study, the in-situ X-ray topographs succeeded to capture dynamic elongation of defects and dislocation generated in the SiC growing crystals. The in-situ rocking curve measurement reviled appearance of mosaic structure in the SiC crystal grown with high growth rate. The in-situ growth rate monitoring also succeeded very precisely using the direct X-ray beam absorption. On the base of findings and facts obtained by the in-situ observations, the importance for the SiC growth was discussed.     

Focal calcium monitoring with targeted nanosensors at the cytosolic side of endoplasmic reticulum

Ca²⁺ distribution is spatially and temporally non-uniform inside cells due to cellular compartmentalization. However, Ca²⁺ sensing with small organic dyes, such as fura-2 and fluo-4, has been practically applied at a single cell level where the averaged signal from freely diffusing dye molecules is acquired. In this study, we aimed to target azide-functionalized fura-2 (N₃-fura-2) to a specific site of subcellular compartments to realize focal Ca²⁺ sensing. Using scAVD (single-chain avidin)–biotin interaction and a copper-free click reaction system, we linked N₃-fura-2 to specifically-targeted scAVD protein fused with a red fluorescent protein mCherry, so that Ca²⁺ sensors conjugated with four N₃-fura-2 dyes with dibenzocyclooctyne (DBCO)-PEG4-biotin as a linker were generated at subcellular compartments in living cells. In cytoplasm, N₃-fura-2 showed a prolonged retention period after binding to scAVD. Furthermore, the reacted N₃-fura-2 was retained inside cells even after free dyes were washed out by methanol fixation. When scAVD was overexpressed on endoplasmic reticulum (ER) membranes, N₃-fura-2 was accumulated on ER membranes. Upon histamine stimulation, which increases cytosolic Ca²⁺ concentration, ER-localized N₃-fura-2 successfully sensed the Ca²⁺ level changes at the cytosolic side of ER membrane. Our study demonstrated specific targeting of N₃-fura-2 to subcellular compartments and the ability of sensing focal Ca²⁺ level changes with the specifically targeted Ca²⁺ sensors.     

Comparative immunohistological study on using capsaicin,piperine, and okadaic acid for the transepithelial passage of the inactivated viral and bacterial vaccines in fish

The practical difficulty of parenteral application of fish vaccines against devastating fish diseases diverted the interest toward oral vaccination. Search for effective methods to enhance the oral uptake of viral and bacterial vaccines is continuing. The current research focus on a new role of mucosal fish vaccine adjuvants inducing the antigen uptake by enhancing vascularity or increasing intestinal permeability. Some inflammatory substances cause reversible pathology to the intestinal epithelium, which could be employed for the transepithelial passage of vaccine particles. The natural inflammatory substances used were capsaicin, piperine, and okadaic acid as 1 mg, 2 mg, and 1 μg/fish, respectively. Two inactivated vaccines were used as antigens to test the effect of these inflammatory substances in two different fish hosts. Tested vaccines were inactivated redspotted grouper nervous necrosis virus vaccine in sevenband grouper (Epinephelus septemfasciatus) and inactivated Edwardsiella tarda vaccine in red sea bream (Pagrus major) fish models. The inflammatory substances and each vaccine were anally intubated to fish. Capsaicin proved to be effectively aiding the transepithelial passage of vaccine particles more than piperine, while okadaic acid had no detectable effect.     

Far infrared optical properties of amorphous semiconductors As−S systems

Far infrared reflection, Raman, and Brillouin spectra of amorphous semiconductor As?S systems are measured. From the reflection spectra, the optical constants are calculatured by the Kramers Kronig analysis. The existence of some intermediate range interaction among molecular units AsS₃ is suggested. From the analysis of the Boson peak at low frequency region in Raman scattering, the correlation length is obtained to be ca. 6 Å. From the absorption coefficient in the low frequency region about 3% fluctuation of charge is suggested for As₂S₃ by schlömann theory.     

Analysis of Moiré Fringes Produced by Centrosymmetric Gratings

Abstract

A method of describing centrosymmetric gratings (radial, circular and spiral) is presented. The moiré-fringe profile produced by centrosymmetric gratings is analysed using polar coordinates. The concept of the angle of intersection for two superimposed gratings is examined and it is shown how from this study moiré patterns formed from centrosymmetric gratings can be analysed automatically by digital computer. Examples of theoretically predicted patterns, generated by the proposed procedure, are compared with actual moiré-fringe patterns. This method provides for the first time a procedure that can be used in engineering for improving the contrast of moiré patterns and for sharpening these patterns.     

Connection‐Strength Estimation of Neuronal Networks by Fitting for Izhikevich Model

Recently, there has been abundant research using multineuron recording, but there are many problems with extracting the features from the obtained spike time series, which are huge in volume and complex. Here we introduce a new method of estimating synaptic connection strengths between neurons by fitting to the Izhikevich model by maximum likelihood estimation. We demonstrate that our method can estimate connection strengths from spike time series given by a simulated neural ensemble and can estimate nonconnectivity between two independent cultured neuronal networks. These results suggest that our method is applicable to network and plasticity analysis of neuronal networks.     

Experimental implementation and analysis of robotic metal spinning with enhanced trajectory tracking algorithms

Metal spinning is a plastic forming process in which a disk or tube of metal is rotated at high speed and forced onto a mandrel. It is widely used in industry as an efficient, modern and economical production technique. This research proposes to develop a versatile robotic forming method and expand the application areas of robotic manufacturing processes to the metal spinning area. A lathe-type laboratory setup has been built and an industrial robot manipulator has been used to implement the metal spinning process. Experiments have been conducted with enhanced cascaded trajectory tracking algorithms with an add-on vibration suppressor. The potential of the proposed method has been illustrated with extensive case studies using both constant and variable speed trajectory profiles. Analyses for the growth of wrinkles have been performed through the topographical measurements of the products and the forming forces have been inspected. Results indicate that the efficiency of the process can be significantly improved with suitably selected variable speed trajectory profiles and the process parameters. The developed scheme successfully reduces the excessive oscillations of the manipulator during the metal spinning process and it requires no additional hardware to employ. The investigations demonstrate the feasibility of robotic metal spinning using an industrial serial link manipulator.