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  • Springer  (45)
  • American Institute of Physics  (3)
  • 2020-2023
  • 1990-1994  (31)
  • 1985-1989  (17)
  • 1950-1954
  • 1945-1949
  • 1910-1914
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  • 1
    Electronic Resource
    Electronic Resource
    Machine setup and component placement in printed circuit board assembly (1994)
    Springer
    International journal of flexible manufacturing systems 6 (1994), S. 5-31 
    Details
    ISSN: 1572-9370
    Keywords: printed circuit board assembly ; surface mount technology ; quadratic integer programming ; dynamic programming
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Populating printed circuit boards is one of the most costly and time-consuming steps in electronics assembly. At the beginning of each work order, three decisions are required: (1) a sequence must be specified for placing the individual components on the board; (2) tape reels must be assigned to positions on the magazine rack; and (3) a retrieval plan must be determined should the same component type be assigned to more than one magazine slot. Collectively, these problems can be modeled as a nonlinear integer program. In this paper, we develop a series of algorithms for solving each using an iterative two step approach. Initially, a placement sequence is generated with a weighted, nearest neighbor traveling salesman problem (TSP) heuristic; the two remaining problems are then formulated as a quadratic integer program and solved with a Lagrangian relaxation scheme. As a final step, the current magazine assignments are used to update the placement sequence, and the entire process is repeated. Our ability to deal, at least in part, with simultaneous machine operations represents the major contribution of this work. The methodology was simulated for a set of boards obtained from Texas Instruments and theoretically compared with a heuristic currently in use.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01324873
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  • 2
    Electronic Resource
    Electronic Resource
    An algorithm for the mixed-integer nonlinear bilevel programming problem (1992)
    Springer
    Annals of operations research 34 (1992), S. 149-162 
    Details
    ISSN: 1572-9338
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Economics
    Notes: Abstract The bilevel programming problem (BLPP) is a two-person nonzero sum game in which play is sequential and cooperation is not permitted. In this paper, we examine a class of BLPPs where the leader controls a set of continuous and discrete variables and tries to minimize a convex nonlinear objective function. The follower's objective function is a convex quadratic in a continuous decision space. All constraints are assumed to be linear. A branch and bound algorithm is developed that finds global optima. The main purpose of this paper is to identify efficient branching rules, and to determine the computational burden of the numeric procedures. Extensive test results are reported. We close by showing that it is not readily possible to extend the algorithm to the more general case involving integer follower variables.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02098177
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  • 3
    Electronic Resource
    Electronic Resource
    The electrochemical reduction of CO2 to CH4 and C2H4 at Cu/Nafion electrodes (solid polymer electrolyte structures) (1988)
    Springer
    Catalysis letters 1 (1988), S. 73-79 
    Details
    ISSN: 1572-879X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The construction of copper/Nafion electrodes (solid polymer electrolyte structures) by an electroless plating method is described. These electrodes were used for the gas phase electrochemical reduction of CO2 to hydrocarbon products, including CH4 and C2H4. The faradaic efficiencies of the electrodes under ambient conditions with a counter solution of 1 mM H2SO4 at a potential of −2.00 V vs. SCE reached a steady-state value of about 20% after 30 min of electrolysis. This corresponded to a rate of total hydrocarbon production of approximately 9.8×10−7 mole h−1 cm−2. Increasing the potential of the electrode to more negative potentials, or increasing the proton concentration of the counter solution, caused a decrease in the faradaic efficiencies due to a relative increase in the rate of proton reduction vs. that of CO2 reduction. If the proton concentration of the counter solution was decreased to an alkaline pH, hydrocarbon production quickly ceased because of proton starvation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00765357
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  • 4
    Electronic Resource
    Electronic Resource
    Photoactivity of ternary lead-group IVB oxides for hydrogen and oxygen evolution (1990)
    Springer
    Catalysis letters 5 (1990), S. 61-66 
    Details
    ISSN: 1572-879X
    Keywords: Photocatalysis ; photocatalytic activity ; PbCrO4 ; PbMoO4 ; PbWO4 ; hydrogen evolution ; oxygen evolution ; aqueous solutions ; ternary lead Group IVB oxides
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The relative photocatalytic activity of a series of lead-IVB group oxides (PbCrO4, PbMoO4, and PbWO4) was studied for hydrogen evolution from aqueous methanol solution and for oxygen evolution from aqueous silver nitrate solution. Among the compounds, only PbMoO4 and platinized PbMoO4 powders acted as photocatalysts for oxygen and hydrogen evolution reactions from aqueous solutions, with an activity for oxygen evolution on PbMoO4 comparable to that observed on TiO2.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00772094
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  • 5
    Electronic Resource
    Electronic Resource
    When is partial trace equivalence adequate? (1994)
    Springer
    Formal aspects of computing 6 (1994), S. 317-338 
    Details
    ISSN: 1433-299X
    Keywords: Process algebra ; Trace semantics ; Structured operational semantics ; Determinism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Two processes arepartial trace equivalent iff they can perform the same sequences of actions in isolation. Partial trace equivalence is perhaps the simplest possible notion of process equivalence. In general, it is too simple: it is not usually an adequate semantics. We investigate the circumstances under which it is adequate, which are surprisingly rich. We give two substantial classes of languages for which partial traces are adequate. In one class, partial trace equivalence suffices for total correctness, and operations such as true sequencing are possible; but all processes are determinate and silent moves are not possible. The other class — which includes many standard process calculi, such as CCS and CSP — admits indeterminacy and silent moves, but partial traces only suffice for partial correctness and true sequencing is not definable.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01215409
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  • 6
    Electronic Resource
    Electronic Resource
    Convex two-level optimization (1988)
    Springer
    Mathematical programming 40 (1988), S. 15-27 
    Details
    ISSN: 1436-4646
    Keywords: Bilevel programming ; Stackelberg games ; branch and bound ; active set strategy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract In this paper a model for a two-level planning problem is presented in the form of a static Stackelberg game. By assumption, play is sequential and noncooperative; however, the leader can influence the actions of the followers through a set of coordination variables while the followers' responses may partly determine the leader's payoff. Under certain convexity assumptions, it is shown that the feasible region induced by the leader is continuous in the original problem variables. This observation, coupled with two corollary results, are used as a basis for a hybrid algorithm which clings to the inducible region until a local optimum is found. A branching scheme is then employed to located other segments of the region, eventually terminating with the global optimum. A number of examples are given to highlight the results, while the algorithm's performance is tested in a comparison with two other procedures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01580720
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  • 7
    Electronic Resource
    Electronic Resource
    A traction-based mechanism for somitogenesis in the chick (1988)
    Springer
    Development genes and evolution 197 (1988), S. 513-517 
    Details
    ISSN: 1432-041X
    Keywords: Cell adhesion ; Condensation ; Mechanism ; Somitogenesis ; Traction
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary This paper suggests that chick somites form because presomitic cells exert tractional forces on one another. These forces derive from the increase in cell adhesion and density that occurs as N-CAM and N-cadherin are laid down by the motile cells of the presomitic mesoderm, well before the somites form. Harris et al. (1984) have shown that adhesive and motile cells in an appropriate environment in vitro can spontaneously form aggregates under the influence of the tractional forces that they exert. Presomitic mesodermal cells may behave similarly: as CAM production increases local adhesivity, the tractional forces between the cells should become sufficiently strong for groups of cells to segment off the mesenchyme as somites. The successive expression of CAMs down the presomitic mesoderm will thus lead to the formation of an anterior-posterior sequence of somites. This mechanism can explain several aspects of somitogenesis that models generating a repetitive pre-pattern through gating cohorts of cells find hard to explain: first, mesodermal segregation occurs among highly adherent cells; second, that multiple rows of somites can form in embryos cultured on highly adherent substrata; third, that stirred mesoderm will still form normal somites; and, fourth, how somite size can be altered in heat-shocked embryos and elsewhere. Suggestions are given as to how the mechanism may be tested and where else in the embryo it could apply.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385686
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  • 8
    Electronic Resource
    Electronic Resource
    Reconstruction of the last deglaciation: deconvolved records of δ18O profiles, micropaleontological variations and accelerator mass spectrometric14C dating (1987)
    Springer
    Climate dynamics 1 (1987), S. 101-112 
    Details
    ISSN: 1432-0894
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract Bioturbation acts as a low-pass filter in displacing and reducing the amplitudes of stratigraphic signals. This often leads to a loss of high-frequency events in the stratigraphic record. In addition, when considering an isotopic signal δ18O,14C measured in stratigraphic “carriers”, such as foraminifera, bioturbation and carrier abundance changes can create artifacts which may be falsely interpreted as leads or lags in the paleoclimatic record. We presenthere a model in which bioturbationis treated as a time-invariant filter whose impulse response function (IRF) is like that of a first-order system. The method involves first deconvoluting the abundance curves of the carriers and then the isotopic signals using the restored “carrier” abundances. This analysis was initially used to artificially generate ideal curves, with the aim of qualitatively modelling the effects of bioturbation. Following this, deconvolved curves were obtained using data from the core CH73-139C using δ18O, A. M. S. C-14 ages, and abundances of two planktonic foraminifera:G. bulloides andN. pachyderma left-coiling. A comparison of the data with the unmixed curves enables separation of the bioturbation artifacts and the construction of a common deglaciation curve based on the restored signals. Importantly, the model emphasizes some severe limitations of mathematical analysis of stratigraphic signals.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01054479
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  • 9
    Electronic Resource
    Electronic Resource
    Polymorphisms of the apolipoprotein B and E genes and their relationship to plasma lipid variables in healthy Chinese men (1993)
    Springer
    Human genetics 〈Berlin〉 92 (1993), S. 191-197 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract In this study we have analysed the apolipoprotein (Apo) E polymorphism and polymorphisms of the ApoB gene, including the ApoB/Xba I and ApoB/4311 diallelic polymorphisms and a hypervariable region (HVR) situated in the 3′ region of the gene (ApoB/3′HVR), in a sample of healthy male subjects from Taiyuan (northern People's Republic of China). In comparison to Caucasian populations, in the Chinese sample, the Xba I2 allele (presence of cutting site; frequency 6.1%; and 95% confidence interval, 3.3–8.9) and the long HVR alleles (9.4%; 6.0–12.8) were rare, whereas the ApoB/4311 (Ser) allele (70.8%; 65.4–76.2) and the 34-repeat allele of the HVR (HVR34; 62.4%; 56.8–68.0) were frequent. In subjects having none, one, or two HVR34 alleles, the mean levels of plasma triglycerides were 2.32±1.44 (SD), 1.45+0.74, and 1.75±1.07 g/l, respectively (P 〈 0.007). Similar trends were observed for very low density lipoprotein (VLDL) cholesterol, LpE:B, and LpCIII:B. The frequencies of the ApoE alleles were similar to those reported in other populations of Asian origin; E2 (7.4%; 4.2–10.6), E3 (84.4%; 80.2–88.6), and E4 (8.2%; 5.0–11.4). Individuals carrying the E2 allele had a lower mean level of ApoB than E33 individuals: 0.87±0.16 and 1.00±0.22 g/l, respectively (P 〈 0.007). Individuals carrying the E4 allele had higher levels of ApoE than E33 individuals: 0.140±0.084 and 0.094±0.052 g/l, respectively (P 〈 0.004); similar trends were observed for VLDL cholesterol, triglycerides, LpE:B, and LpCIII:B. The ApoB/ HVR34 and ApoE/E4 polymorphisms accounted for 10% to 15% of the variability of the plasma levels of VLDL cholesterol, ApoE, triglycerides, LpE:B, and LpCIII:B. Several lipid variables appeared to be favourably affected by specific forms of ApoB and ApoE that are particularly frequent in this Chinese population.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00219691
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  • 10
    Electronic Resource
    Electronic Resource
    A distinctive change in odortype determined by H-2D/L mutation (1991)
    Springer
    Immunogenetics 34 (1991), S. 129-131 
    Details
    ISSN: 1432-1211
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00211425
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