Showing papers by "Michigan Technological University published in 1987"
TL;DR: An intermediate program representation, called the program dependence graph (PDG), that makes explicit both the data and control dependences for each operation in a program, allowing transformations to be triggered by one another and applied only to affected dependences.
Abstract: In this paper we present an intermediate program representation, called the program dependence graph (PDG), that makes explicit both the data and control dependences for each operation in a program. Data dependences have been used to represent only the relevant data flow relationships of a program. Control dependences are introduced to analogously represent only the essential control flow relationships of a program. Control dependences are derived from the usual control flow graph. Many traditional optimizations operate more efficiently on the PDG. Since dependences in the PDG connect computationally related parts of the program, a single walk of these dependences is sufficient to perform many optimizations. The PDG allows transformations such as vectorization, that previously required special treatment of control dependence, to be performed in a manner that is uniform for both control and data dependences. Program transformations that require interaction of the two dependence types can also be easily handled with our representation. As an example, an incremental approach to modifying data dependences resulting from branch deletion or loop unrolling is introduced. The PDG supports incremental optimization, permitting transformations to be triggered by one another and applied only to affected dependences.
2,631 citations
TL;DR: In this article, a simplified physical picture is extracted from the many complicated processes occuring during plastic deformation, based upon a set of continuously distributed straight edge dislocations, the carriers of plastic deformations, moving along their slip plane, interacting with each other and the lattice, multiplying and annihilating.
936 citations
TL;DR: In this paper, the atomic positions which attend the formation of growth twins on {111} planes are investigated and it is shown that adsorbed impurity atoms of suitable size, on the solid-liquid interface, could be responsible for changing the stacking sequence, so promoting impurity induced twinning.
Abstract: Modification of silicon by sodium in aluminum silicon eutectic alloy has been examined in detail by optical, SEM, and TEM methods. The aluminum phase is not significantly affected but the silicon becomes very heavily twinned. Modification by quenching does not involve an increase in twin density. Consideration of the atomic positions which attend the formation of growth twins on {111} planes suggests that adsorbed impurity atoms of suitable size, on the solid-liquid interface, could be responsible for changing the {111} stacking sequence, so promoting ‘impurity induced twinning’; the optimum hard sphere radius ratio would be ≈ 1.65. It is proposed that this condition could be the first and principal requirement for a modifying agent to be effective in this system. It is shown further, that other reputed modifiers do also induce a higher twin density. Variations in the efficiency of individual elements to promote such an effect are discussed in terms of other relevant factors which include melting points and vapor pressures, the free energies of formation of compounds — notably of oxides, and the forms of alloy phase diagrams.
506 citations
TL;DR: The authors of as discussed by the authors reported that the Merapi volcanic gas is enriched by factors greater than 105 in Se, Re, Bi and Cd; 104-105 in Au, Br, In, Pb and W; 103-104 in Mo, Cl, Cs, S, Sb, S.C., S.S., N.S. and Ag, and less than 103 g d of Ni, Cu, Cr, Ni, Ni and Co.
311 citations
TL;DR: One of Earth9s largest known eruptions, the Toba eruption of 75 ka, erupted a minimum of 2800 km 3 of magma, of which at least 800 km 3 was deposited as ash fall as discussed by the authors.
Abstract: One of Earth9s largest known eruptions, the Toba eruption of 75 ka, erupted a minimum of 2800 km 3 of magma, of which at least 800 km 3 was deposited as ash fall. This ash may be entirely of coignimbrite origin and dispersed widely because of high drag coefficients on the predominantly bubble-wall shards. Shards of this shape are broken from the walls of spherical vesicles, which formed in high abundance in isotropic strain shadows near phenocrysts in this crystal-rich magma.
255 citations
TL;DR: In this paper, it was shown that class E operation may be maintained with the RF choke replaced by a smaller reactance, which is similar to that used by Raab in his description of class E amplifiers in that the equations describing circuit operation are obtained from Fourier series methods and the assumption of an infinite output network Q.
Abstract: Previous descriptions of class E amplifiers and frequency multipliers have required a radio frequency choke between the dc power supply and the active device "switch." In this paper, it is shown that class E operation may be maintained with the RF choke replaced by a smaller reactance. The analysis technique used is similar to that used by Raab in his description of class E amplifiers in that the equations describing circuit operation are obtained from Fourier series methods and the assumption of an infinite output network Q . The equations so obtained are used to determine (1) optimum operation (maximum power output capability at 100-percent efficiency) at any harmonic and (2) design equations that yield the requisite component values for optimum operation. The equations show that class E circuits may be configured to accommodate devices with arbitrary output capacitance and that class E amplifiers may be configured to provide greater power output capability than can be obtained using an RF choke design. Class E circuits with moderate values of output network Q were constructed and tested. The measured performance of these experimental circuits shows excellent agreement with the theoretical performance predicted by the equations.
213 citations
TL;DR: In this article, a large deformation viscoplastic model is proposed, which includes the effects of static and dynamic recovery in its strain rate response as well as the plastic spin in its rotational response.
Abstract: We propose a new large deformation viscoplastic model which includes the effects of static and dynamic recovery in its strain rate response as well as the plastic spin in its rotational response. The model is directly obtained from single slip dislocation considerations with the aid of a maximization procedure and a scale invariance argument. It turns out that the evolution of the back stress and the expression for the plastic spin are coupled within the structure of the theory. The model is used for the prediction of nonstandard effects in torsion, namely the development of axial stress and strain as well as the directional softening of the shear stress. The comparisons between the present continuum model and both experiments and self-consistent polycrystalline calculations are very encouraging.
97 citations
01 Jan 1987
88 citations
TL;DR: In this paper, an empirical expression relating T c to the amounts of moly b-denum and titanium as well as to the aluminum content was derived for a variety of alloys, both ternary and higher order.
83 citations
TL;DR: In this paper, modified methods for the measurement of interparticle spacing and undercooling of the Al-Si eutectic have been applied in an attempt to test the applicability to this system of the accepted equation for diffusion-controlled normal eUTectic growth.
Abstract: Modified methods for the measurement of interparticle spacing and undercooling of the Al-Si eutectic have been applied in an attempt to test the applicability to this system of the accepted equation for diffusion-controlled normal eutectic growth. Good agreement with some published measurements has been obtained. For the unmodified and chill-modified eutectic microstructures it seems probable that the basic equation is applicable but that the extremum condition is not. For the impurity modified eutectic there is no agreement with the theoretical prediction, although the possibility is advanced of adding an undercooling term based on twin boundary energy.
81 citations
TL;DR: In this paper, a simple, analytically tractable model of recirculating inertial gyres is presented, which is contained in a rectangular box in an attempt to simplify the geometry as much as possible and to isolate the processes occurring in the Recirculating region.
Abstract: Some essential features of a recirculating inertial gyre (the “recirculation”) can be analyzed with a very simple, analytically tractable model. In wind-driven eddy-resolving general circulation models the recirculation appears as a strong sub-basin-scale inertial flow with homogeneous potential vorticity. The constant value of potential vorticity decreases with increasing forcing/dissipation ratio while the size and the strength of the recirculating gyre increases. In the subtropical gyre the recirculating gyre might be driven by anomalous values of low potential vorticity carried northward by the western boundary current. We have modeled this process using a barotropic model and prescribing the values of potential vorticity at the edge of the gyre. Our model gyre is contained in a rectangular box in an attempt to simplify the geometry as much as possible and to isolate the processes occurring in the recirculating region. With weak diffusion the prescribed boundary forcing induces a flow with co...
TL;DR: In this article, the authors measured the diffusivity of the Ni-Cr-Al diffusion couples at 1100 and 1200 °C in the Ni solid solution γ (fcc) phase.
Abstract: Ternary interdiffusion coefficients were measured in the Ni solid solution γ (fcc) phase of the Ni-Cr-Al system at 1100 and 1200 °C. Extensive use was made of both γ/γ and γ/γ + β (β-NiAl structure) diffusion couples. Two analysis techniques were employed to calculate the interdiffusion coefficients. When the Matano planes for Al and Cr were not coincident, numerous integral calculations were made to determine an average diffusion coefficient and to assess the effect of the noncoincidence of the Matano planes. The results of the diffusivity measurements showed that
% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9qqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmirayaaia% Waa0baaSqaaGqaaiaa-feacaWFSbGaa8xqaiaa-XgaaeaacaWFobqc% baKaa8xmaaaaaaa!3C04!
$$\tilde D_{AlAl}^{N1} $$
is approximately four times greater than
% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9qqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmirayaaia% Waa0baaSqaaGqaaiaa-feacaWFSbGaa83qaiaa-jhaaeaacaWFobqc% baKaa8xmaaaaaaa!3C0C!
$$\tilde D_{AlCr}^{N1} $$
, while
% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9qqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmirayaaia% Waa0baaSqaaGqaaiaa-neacaWFYbGaa8xqaiaa-XgaaeaacaWFobqc% baKaa8xmaaaaaaa!3C0C!
$$\tilde D_{CrAl}^{N1} $$
and
% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9qqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmirayaaia% Waa0baaSqaaGqaaiaa-neacaWFYbGaa83qaiaa-jhaaeaacaWFobqc% baKaa8xmaaaaaaa!3C14!
$$\tilde D_{CrCr}^{N1} $$
are of the same magnitude. For all concentrations,
% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9qqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmirayaaia% Waa0baaSqaaGqaaiaa-feacaWFSbGaa8xqaiaa-XgaaeaacaWFobqc% baKaa8xmaaaaaaa!3C04!
$$\tilde D_{AlAl}^{N1} $$
is two to three times greater than
% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9qqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmirayaaia% Waa0baaSqaaGqaaiaa-neacaWFYbGaa83qaiaa-jhaaeaacaWFobqc% baKaa8xmaaaaaaa!3C14!
$$\tilde D_{CrCr}^{N1} $$
. Both
% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9qqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmirayaaia% Waa0baaSqaaGqaaiaa-feacaWFSbGaa8xqaiaa-XgaaeaacaWFobqc% baKaa8xmaaaaaaa!3C04!
$$\tilde D_{AlAl}^{N1} $$
and
% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9qqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmirayaaia% Waa0baaSqaaGqaaiaa-feacaWFSbGaa83qaiaa-jhaaeaacaWFobqc% baKaa8xmaaaaaaa!3C0C!
$$\tilde D_{AlCr}^{N1} $$
increase with increasing Al concentration, whereas
% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9qqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmirayaaia% Waa0baaSqaaGqaaiaa-neacaWFYbGaa8xqaiaa-XgaaeaacaWFobqc% baKaa8xmaaaaaaa!3C0C!
$$\tilde D_{CrAl}^{N1} $$
and
% MathType!MTEF!2!1!+-% feaafiart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXatLxBI9gBaerbd9wDYLwzYbItLDharqqtubsr% 4rNCHbGeaGqiVu0Je9qqqrpepC0xbbL8F4rqqrFfpeea0xe9Lq-Jc9% vqaqpepm0xbba9pwe9Q8fs0-yqaqpepae9pg0FirpepeKkFr0xfr-x% fr-xb9adbaqaaeGaciGaaiaabeqaamaabaabaaGcbaGabmirayaaia% Waa0baaSqaaGqaaiaa-neacaWFYbGaa83qaiaa-jhaaeaacaWFobqc% baKaa8xmaaaaaaa!3C14!
$$\tilde D_{CrCr}^{N1} $$
show little concentration dependence on Cr alone. A ternary, finite-difference interdiffusion model was employed to predict concentration profiles for the γ/γ couples utilizing the concentration dependence of the measured diffusivities. Good agreement was observed between the predicted and measured concentration profiles for both 1100 and 1200 °C.
TL;DR: Although large joint displacements were necessary for complete ligament failure, bundle disruption in the MCL, ACL, and PCL was noted at much smaller joint openings and no significant protection could be documented with the two preventive braces used.
Abstract: To better understand the role of preventive knee braces in injury prevention, a biomechanical study using fresh frozen cadaveric knees (N = 18) was conducted. Liga ment tensions and joint displacements were measured at static, nondestructive valgus forces as well as low- rate destructive forces. After quantifying and establish ing individual ligament contributions to valgus restrain ing function, knees were then braced with two different laterally applied preventive braces, the McDavid Knee Guard and the Omni Anderson Knee StabIer.The effects of lateral bracing were analyzed according to valgus force, joint line opening, and ligament tensions.Valgus applied forces, with or without braces, consis tently produced medial collateral ligament (MCL) disrup tions at ligament tensions surprisingly higher than the anterior cruciate ligament (ACL) and higher than or equal to the posterior cruciate ligament (PCL). Although large joint displacements were necessary for complete ligament failure, bundle disruption in t...
TL;DR: In this paper, a more general rule, "the three numbers must be different" was used to solve Wason's 2-4-6 task, and the results showed that disconfirming on the three different numbers did not significantly improve their performance.
Abstract: This paper reports two experiments in which subjects worked to solve a more difficult version of Wason's 2–4–6 task: instead of the usual “numbers must ascend in order of magnitude” rule, a more general rule, “the three numbers must be different”, was used. The first experiment established that instructing subjects to disconfirm on the “three different numbers” did not significantly improve their performance, as compared with confirmatory and control groups. Disconfirmatory subjects did try to propose more triples at variance with their hypotheses but were unable to obtain the necessary disconfirmatory information. To help subjects represent the task in a way that facilitated disconfirmation, the second experiment utilized a procedure in which subjects were told that they were looking for two rules, Dax and Med–the Dax rule corresponding to “three different numbers” and the Med rule to its complement, i.e. two or more numbers the same. Of subjects in the Dax–Med condition, 88% solve the rule, as opposed t...
TL;DR: In this article, a model for predicting the strength of two-phase alloys is presented, and the model can be applied to predict the strength for any other two phase alloy as a function of composition, fabrication strain, and interphase spacing.
Abstract: When alloys containing two ductile phases are heavily deformed, composite-like microstructures develop and strengths well in excess of either of the phases in single phase form may be exhibited as a result of microstructure/dislocation density effects. In this paper a previously-published model for such strengthening is reviewed, and its application in a predictive capacity discussed. Flow stressvs fabrication strain data for the two components in single phase form and for one two-phase alloy are necessary for this purpose. The model may then be applied to predict strength for any other two-phase alloy as a function of composition, fabrication strain, and interphase spacing. The approach is illustrated using existing data for several alloy systems. For Ag-Fe and Cu-Nb alloys (with very limited mutual solubility) strengths can be predicted within 15 to 20 pct of the experimental values over the entire range of strains and volume fractions for which data are available. In systems where the potential for precipitation hardening exists (e.g., Cu-Fe) thermal history is important. When such hardening becomes a significant factor, the model cannot be used in its present form due to uncertainty over how to “add” the strengthening from this effect. Such hardening may, however, be useful in further improving the properties of these materials.
TL;DR: In this article, after annealing at 1100 and 1200 °C, the diffusion coefficient of Ni-Cr-Al diffusion couples was studied and the location of maxima and minima in the concentration profiles of several of the diffusion couples indicated that both cross-term diffusion coefficients for Cr and Al are positive and that DCrAl has a greater effect on the diffusion of Cr than does DA1Cr on diffusion of Al.
Abstract: Interdiffusion in Ni-rich, Ni-Cr-Al diffusion couples was studied after annealing at 1100 and 1200 °C. Recession of γ′ (Ni3Al structure), β (NiAl structure), or α (bcc) phases was also measured. Aluminum and chromium concentration profiles were measured in the γ (fcc) phase for most of the diffusion couples. The amount and location of Kirkendall porosity suggests that Al diffuses more rapidly than Cr which diffuses more rapidly than Ni in the γ phase of Ni-Cr-Al alloys. The location of maxima and minima in the concentration profiles of several of the diffusion couples indicates that both cross-term diffusion coefficients for Cr and Al are positive and that DCrAl has a greater effect on the diffusion of Cr than does DA1Cr on the diffusion of Al. The γ/γ + β phase boundary has also been determined for 1200 °C through the use of numerous γ/γ+ β diffusion couples.
TL;DR: An anatomically correct surrogate knee model, instrumented to measure ligament/tendon ten sion and medial joint opening, was developed and validated using information from previous cadaver studies and results of analyses on the effects of high strain rates on MCL failure.
Abstract: In Part I of our study on lateral knee bracing, we evaluated brace effectiveness using cadaveric knees and two commercially available braces (McDavid and Omni). The results indicated that for low-rate dynamic valgus loading, neither brace provided significant pro tection against MCL injury. Also, four potentially ad verse effects were noted. The goals in Part II were to: 1) determine the clinical significance of brace induced MCL preload; 2) define the functional character of an "ideal" brace; 3) design and validate a surrogate knee model for testing brace effectiveness; and 4) determine brace performance under impact loading using the sur rogate knee and six commercially available brace types (manufactured by DonJoy, McDavid, Mueller, Omni Sci entific, Stromgren-Scott, and Tru-Fit). Knee braces, modified to measure varus/valgus bending force, were used to determine MCL preload effects in 13 human volunteers. An anatomically correct surrogate knee model, instrumented to measure ligament/tendon ten sion an...
TL;DR: In this paper, the authors analyzed the spreading of concentration fronts in dynamic column experiments conducted with a porous, aggregated soil by means of a previously documented transport model (DFPSDM) that accounts for longitudinal dispersion, external mass transfer in the boundary layer surrounding the aggregate particles, and diffusion in the intra-aggregate pores.
TL;DR: In this paper, the authors investigated the linear stability problem of convection by the general Oldroyd B fluid and its Maxwell limit in the presence of rigid or free boundaries and fixed temperature or fixed flux.
Abstract: We investigate the linear stability problem of convection by the general Oldroyd B fluid and its Maxwell limit in the presence of rigid or free boundaries and fixed temperature or fixed flux. Comparison with recent results by Rosenblat [9] for the analytically accessible case of free boundary conditions shows a qualitative similarity in the shape of the neutral stability curves. But while Newtonian and Jeffreys (general Oldroyd B) fluids are sharply stabilized by the presence of rigid boundaries, the Maxwell fluid is largely unaffected at even moderately large Prandtl number. The reasons for this are discussed. Also, a discrepancy between the earlier works by Vest and Arpaci [3], and Sokolov and Tanner [4], which treat the case of a Maxwell fluid, is found to be due to algebraic error, and not multivaluedness of the stress-strain rate relation as earlier suggested by Eltayeb [6].
TL;DR: Paleomagnetic and 40Ar/39Ar data indicate that two tuffs are present at Siguragura, North Sumatra, Indonesia: a reversely magnetized tuff (the earliest eruptive unit of the Toba caldera) of Matuyama age (0.84 Ma) and a normally magnetised tuff of late Brunhes age as discussed by the authors.
Abstract: Paleomagnetic and 40Ar/39Ar data indicate that two tuffs are present at Siguragura, North Sumatra, Indonesia: a reversely magnetized tuff (the earliest eruptive unit of the Toba caldera) of Matuyama age (0.84 Ma) and a normally magnetized tuff (the last eruptive unit of the Toba caldera) of late Brunhes age. No reversely magnetized tuffs of late Brunhes age are present at this location as suggested by previous investigators.
TL;DR: The Santa Maria volcano has a three-phase history of activity: a long period of composite cone growth, a dramatic plinian eruption and a dome-extrusion period.
TL;DR: Atitlan caldera has been the site of several silicic eruptions within the last 150,000 years, following a period of basalt/andesite volcanism as mentioned in this paper.
TL;DR: CENTAM as discussed by the authors is a data base of petrological and geochemical data on Central American volcanoes and is available on diskettes readable by IBM-PC and compatible microcomputers.
TL;DR: The Raman and IR vibrational spectra of C-type rare earth sesquioxides exhibit anomalous wavenumber decreases for europium and ytterbium (f13) oxide which have not been previously reported as discussed by the authors.
Abstract: A method is described for optimizing the field stress on HV insulators by modifying their profile, seeking a uniform distribution of the tangential field among the insulator surface. This results in an increase of the onset voltage for surface flashover and in a significant saving of the space of the HV installation. The optimization process was achieved by an algorithm developed for calculating the tangential field Component and mathematical expressions of the profile to be corrected through an iterative procedure. The algorithm was based on a modified charge-simulation technique to satisfy a better matching of the boundary conditions to the electrode and insulator surfaces involved in the HV installation. The algorithm is expanded to study the effect of contamination on the tangential field distribution. It is found that the higher the conductivity of the contamination layer, the higher is the field uniformity along the insulator surface.
TL;DR: In this paper, the authors investigate the disappearance of solutions of the boundary layer model and find that a failure of boundary layer models is coincident with the onset of recirculation in the solution of the partial differential equations at a sufficiently large ratio of basin scale to viscous boundary-layer scale.
Abstract: A nonlinear ordinary differential equation which models the western boundary layer of quasi-geostrophic barotropic models of the wind-driven circulation has been investigated by Il'in and Kamenkovich and more recently by Ierley and Ruehr. For mild nonlinearity the boundary layer model has two possible outflow solutions which match to a Sverdrup interior. For stronger nonlinearity, no solutions exist. In the weakly nonlinear case we use linear stability theory to resolve the problem of multiple solutions. A highly stretched regional model of the full quasi-geostrophic equations is used to investigate the disappearance of solutions of the boundary layer model. We find that a failure of the boundary layer model is coincident with the onset of recirculation in the solution of the partial differential equations at a sufficiently large ratio of basin scale to viscous boundary-layer scale. For less extreme ratios, the onset of recirculation is deferred, and hence its relation to a failure of the boundar...
TL;DR: In all eight species, Echinopsis tubiflora, Pereskia aculeata, Hylocereus undatus, Notocactus scopa, Epiphyllum sp.
TL;DR: In this paper, a new method of computer control of electro-discharge machining based on Data Dependent Systems (DDS) methodology has been recently proposed, which is based on a parameter which effectively represents the resistance of arc and is isolated by the DDS model from the random current and voltage signals.
Abstract: A new method of computer control of electro-discharge machining based on Data Dependent Systems (DDS) methodology has been recently proposed. The control is based on a parameter which effectively represents the resistance of arc and is isolated by the DDS model from the random current and voltage signals in spite of the large noise. This paper presents an experimental verification to show that this parameter indeed represents the arc resistance which cannot be measured by any other means and that the parameter is quite sensitive to the change from beneficial sparking condition to the harmful arcing condition. Off-line analysis of the EDM process under different conditions is presented with this parameter as the response variable. Development of the control strategy using the results of this analysis is illustrated. Implementation of the strategy by means of a Motorola microcomputer is described. A comparison of metal removal rate (MRR), surface roughness, and tool wear for the computer control and the optimal manual adjustment recommended by the EDM machine manufacturer is presented. It shows that the computer control yields an increase in the MRR of 47 percent and 19 percent, while the ratio of tool wear to MRR reduces by 26 percent and 16 percent, respectively, in finishing and roughing conditions.
TL;DR: In this paper, a number of flavonoid derivatives were made with side chains ranging from C 6 to C 16 and tested for fungitoxic and bactericidal activities, and maximum activity was usually found for the decane derivative.