A new hybrid improvement heuristic approach to simple straight and U-type assembly line balancing problems

This paper presents a new hybrid improvement heuristic approach to simple straight and U-type assembly line balancing problems which is based on the idea of adaptive learning approach and simulated annealing. The proposed approach uses a weight parameter to perturb task priorities of a solution to obtain improved solutions. The weight parameters are then modified using a learning strategy. The maximization of line efficiency (i.e., the minimization of the number of stations) and the equalization of workloads among stations (i.e., the minimization of the smoothness index or the minimization of the variation of workloads) are considered as the performance criteria. In order to clarify the proposed solution methodology, a well known problem taken from literature is solved. A computational study is conducted by solving a large number of benchmark problems available in the literature to compare the performance of the proposed approach to the existing methods such as simulated annealing and genetic algorithms. Some test instances taken from literature are also solved by the proposed approach. The results of the computational study show that the proposed approach performs quite effectively. It also yields optimal solutions for all test problems within a short computational time.     

Morphology, axonal projection pattern, and response types of tectal neurons in plethodontid salamanders. I: tracer study of projection neurons and their pathways

In three salamander species (Hydromantes italicus, H. genei, Plethodon jordani), the tectobulbospinal and tectothalamic pathways and their cells of origin were studied by means of anterograde and retrograde biocytin and tetramethylrhodamine tracing. In plethodontid salamanders, five types of tectal projection neurons were identified. TO1 neurons have widefield dendritic trees that arborize in the layers of retinal afferents and form a neuropil in the superficial layer; axons constitute the crossed tectospinal tract. Dendrites of TO2 cells have the largest dendritic trees that arborize in the intermediate and deep layers of retinal afferents; axons constitute a lateral uncrossed tectospinal tract. TO3 cells have widefield dendritic trees that arborize in the deep layer of retinal afferents and in the layer of tectal efferents; axons constitute a superficial uncrossed tectospinal tract. TO4 cells have slender primary dendrites and small-field dendritic trees that arborize in the intermediate layers of retinal afferents; axons constitute another lateral uncrossed tectospinal tract. TO2, TO3, and TO4 cells also have ascending axons that run to the ventral and dorsal thalamus. TO5 cells have slender primary dendrites and small-field dendritic trees that extend into the superficial layers of retinal afferents; their fine axons constitute the bulk of the pathways ascending to the ipsilateral and contralateral thalamus. These morphological types of projection neurons and their ascending and descending axonal pathways closely resemble those found in frogs, reptiles, and birds. Their role in visual and visuomotor functions is discussed.     

Fabrication of antiferroelectric PLZT films on metal foils

Fabrication of high-dielectric-strength antiferroelectric (AFE) films on metallic foils is technically important for advanced power electronics. To that end, we have deposited crack-free Pb_0.92La_0.08Zr_0.95Ti_0.05O₃ (PLZT 8/95/5) films on nickel foils by chemical solution deposition. To eliminate the parasitic effect caused by the formation of a low-permittivity interfacial oxide, a conductive buffer layer of lanthanum nickel oxide (LNO) was coated by chemical solution deposition on the nickel foil before the deposition of PLZT. Use of the LNO buffer allowed high-quality film-on-foil capacitors to be processed in air. With the PLZT 8/95/5 deposited on LNO-buffered Ni foils, we observed field- and thermal-induced phase transformations of AFE to ferroelectric (FE). The AFE-to-FE phase transition field, E_AF = 225 kV/cm, and the reverse phase transition field, E_FA = 190 kV/cm, were measured at room temperature on a ≈1.15 μm-thick PLZT 8/95/5 film grown on LNO-buffered Ni foils. The relative permittivities of the AFE and FE states were ≈600 and ≈730, respectively, with dielectric loss ≈0.04 at room temperature. The Curie temperature was ≈210 °C. The thermal-induced transition of AFE-to-FE phase occurred at ≈175 °C. Breakdown field strength of 1.2 MV/cm was measured at room temperature.     

Fusion reactions in high-density hydrogen: A fast route to small-scale fusion?

High-density atomic hydrogen, which is believed to be a quantum liquid, can be formed by heterogeneous catalysis at the surface of hydrogen-transfer metal oxide catalysts. Extensive studies have been made of the hydrogen phase named H(1), with interatomic distance of 150 pm found by Coulomb explosion measurements. This bond distance corresponds to a material density of 0.5–0.7 kg dm⁻³. The use of this material as fusion target for inertial confinement fusion (ICF) is proposed in J Fusion Energy 2008;27:296–300. A much denser hydrogen (deuterium) material D(−1) also exists with an interatomic distance of 2.3 pm. This material is probably the inverse of metallic D(1), where nuclei and electrons exchange their roles. The ICF process would be greatly simplified if the intended initial multi-laser compression stage was not necessary. The close-packed density of D(−1) is calculated from the bond distance as >130 kg cm⁻³. This is much higher than that required for “fast ignition” laser-driven fusion (>0.3 kg cm⁻³). It may mean that a method already exists to prepare dense hydrogen fuel for small-scale laser-driven fusion. The high energy particles observed experimentally (up to 150 keV/atomic mass unit in the peak or 10⁹ K) indicate that high energy processes exist at relatively low laser intensities.     

Stress-strain state in the grit-matrix system of a diamond tool under force disturbances

The stress-strain state in the grit-matrix system of carbide-bonded diamond tools has been studied by numerical simulation. A transition layer in contact with a diamond grit is shown to be the most heavily loaded portion of the bond. The behavior of stresses in this region has been clarified for variable cutting force directions, properties of the matrix, and the transition layer. Stresses have been analyzed for various extents of the grit embedding in the matrix; critical loading parameters have been determined for various grit shapes and Poisson ratios of the bond.     

Studying physiochemical changes in a new pasta product containing beef heart by vibrational spectroscopy

A new pasta product was developed by partially replacing durum wheat flour with beef heart to enhance its nutritional value. Physiochemical changes of the pasta were investigated by vibrational spectroscopy, namely Fourier transform infrared (FT-IR) and Raman spectroscopy. Relationships between pasta texture and the intensity of vibrational spectra were established. Lipid-protein complex formation, β-sheet arrangement, degree of polysaccharide polymerization, and cysteine thiol group were related to hardness and chewiness of pasta. The lipid portion and β-sheet structure were two significant parameters for explaining pasta adhesiveness, while pasta firmness might be related to β-sheet alignment and the polysaccharide network. Pasta cohesiveness might involve the α-helical structures and hydrogen bonding formation in the gluten network. However, no variable met the p < 0.1 significance level for inclusion into the model to explain pasta springiness. These results reveal that FT-IR and Raman spectroscopy could be employed to evaluate the physical chemistry of pasta and showed a potential use for quality assessment in pasta products.     

Interpretation of partial discharges at dc voltages

The aim of this paper is to give an overview on partial discharges at dc voltage. A model is presented which describes the stochastic discharge process. The model is experimentally verified for internal discharges and for corona in air. In addition, the classification of discharge patterns is discussed. The 3-dimensional histogram describing the number of discharges depending on the discharge magnitude and on the time to the successive discharge is suggested to be used as a base for discharge recognition at dc voltage. Experimental proof is presented to show the strength of this approach     

Scavenging of As from acid mine drainage by schwertmannite and ferrihydrite: a comparison with synthetic analogues

Ochreous precipitates containing 5.5-69.8 g/kg As were isolated from mine drainage in Finland and were composed of schwertmannite, ferrihydrite, and goethite. Schwertmannite formation was favored at pH 3-4, but its structure was degraded at high As levels. A series of coprecipitates were therefore prepared from mixed iron arsenate/sulfate solutions to define the limits of schwertmannite stability. Schwertmannite was replaced as the dominant phase by a poorly crystalline ironIII hydroxy arsenate (FeOHAs) when As/Fe mole ratios exceeded 0.15. The FeOHAs gave an X-ray diffraction pattern similar to that obtained from an "amorphous" ironIII arsenate (As/Fe = 1.0) with broad peaks at 0.30 and 0.16 nm. The FeOHAs possessed a magnetic hyperfinefield of 41.9T at 4.2 K that was intermediate to those of schwertmannite (46.1 T) and the ironIII arsenate (24.8 T). These data indicate a strong disruptive effect of arsenate on magnetic ordering and structure development in schwertmannite. Equilibration of 0.01 M arsenate solutions with freshly prepared schwertmannite and 2-line ferrihydrite at pH 3.0 for up to 60 d gave sorbed As contents of 175 and 210 g/kg, respectively. Arsenate sorption degraded the host schwertmannite and ferrihydrite, perhaps due to the formation of an FeOHAs surface phase.     

Evidence that leptin contributes to intestinal cholesterol absorption in obese (ob/ob) mice and wild-type mice

In the present study, the effect of leptin on intestinal cholesterol absorption was investigated in C57 BL/6 OlaHsd Lep^ob/Lep^ob obese (ob/ob) mice and lean C57 BL/6 (wild-type) mice. Animals were treated either with or without recombinant leptin for 2 wk. Cholesterol absorption was measured by the constant isotope feeding method and indirectly by the ratio of campesterol to cholesterol in serum. In ob/ob mice, cholesterol absorption was significantly higher compared to wild-type mice [83.4±2.3% (SD) vs. 77.6±1.5%, P<0.01]. Treatment with leptin significantly reduced cholesterol absorption in both ob/ob and wild-type mice by 8.5 (P<0.001) and 5.2% (P<0.05), respectively. Serum concentrations of campesterol and the ratio of campesterol to cholesterol in ob/ob mice were significantly higher compared to wild-type mice (2.2±0.3 mg/dL vs. 1.2±0.3 mg/dL, P<0.001; and 36.8±2.8 μg/mg vs. 28.0±3.3 μg/mg, P<0.001). After treatment of ob/ob mice with leptin, concentrations of campesterol and its ratio to cholesterol were significantly lower (2.2±0.3 mg/dL vs. 1.0±0.2 μg/mg, P<0.001; and 36.8±2.8 μg/mg vs. 13.2±2.2 μg/mg, P<0.001, respectively). In wild-type mice, the ratio of campesterol to cholesterol in serum was also significantly lower after treatment with leptin (28.0±3.3 μg/mg vs. 22.6±5.0 μg/mg, P<0.05). A significant positive correlation (r=0.701, P<0.01) between cholesterol absorption and the ratio of campesterol to cholesterol, in serum was found. It is concluded that leptin contributes to intestinal cholesterol absorption in ob/ob mice and lean wild-type mice.