GIS integration model for geothermal exploration and well siting

The work involved in identifying geothermal fields can be simplified by means of a Geographical Information System (GIS), a decision-making tool used to determine the spatial association between exploration and environmental thematic maps. This methodology has been applied to part of the Sabalan geothermal field in northwestern Iran, and to the siting of exploration wells. The datasets used in the analyses consist of geological, geochemical and geophysical information. Boolean and Index Overlay knowledge-driven models were developed for site selection; the findings from these two models correlated well with the exploration data modeling. The results of the Index Overlay model were combined with those of an environmental suitability analysis for final selection of well sites. The results of exploration and environmental data modeling were combined to select and prioritize the sites of three exploratory wells in the study area.     

Stability limits and NO emissions of premixed swirl ammonia-air flames enriched with hydrogen or methane at elevated pressures

This study reports measurements of stability limits and exhaust NO mole fractions of technically-premixed swirl ammonia-air flames enriched with either methane or hydrogen. Experiments were conducted at different pressures from atmospheric to 5 bar, representative of commercial micro gas turbines. The full range of ammonia fractions in the fuel blend, x_NH3, was considered, from 0 (pure methane or hydrogen) to 1 (pure ammonia), covering very lean (φ = 0.25) to rich (φ = 1.60) equivalence ratios. Results show that increasing pressure widens the range of stable equivalence ratios for pure ammonia-air flames. Regardless of pressure, there is a critical ammonia fraction above which the range of stable equivalence ratios suddenly widens. This is because flashback does not occur anymore when the equivalence ratio is progressively increased towards stoichiometric and rich blowout occurs instead. This critical ammonia fraction increases with pressure and is larger for ammonia-hydrogen than for ammonia-methane. Provided that enough hydrogen is blended with ammonia (x_NH3 < 0.9), flames with very lean equivalence ratios (φ < 0.7) can be stabilized and these yield competitively low NO emissions (<200 ppm), regardless of pressure. For this reason, very lean swirl ammonia-hydrogen-air flames are promising candidates for micro gas turbines. However, N₂O emissions have the potential to be unacceptably large for these operating conditions if heat loss is too large or residence time is too short. As a consequence, the post flame region must be considered carefully. Due to the lower reactivity of methane compared to that of hydrogen, very lean swirl ammonia-methane-air flames could not be stabilized and good NO performance is limited to rich equivalence ratios for ammonia-methane fuel blends. The equivalence ratio above which good NO performance depends on pressure and bulk velocity.     

Relationship between J-integral and averaged strain-energy density for U-notches in the case of large control volume under Mode I loading

The main purpose of this technical note is to present a relationship between J-integral and averaged strain-energy density () in U-notches under Mode I loading for brittle or quasi-brittle materials. In this work, control volume includes the rectilinear edge of the notch in addition to semi-circular arc of the notch root. A dimensionless function (f) between J and has been presented in this paper. Finite element analysis has been used for verification. It is found that this relationship is identical for tension or bending loading.     

Kinetic speciation of Co(II), Ni(II), Cu(II), and Zn(II) in model solutions and freshwaters: lability and the d electron configuration

The kinetic speciation of Co(II), Ni(II), Cu(II), and Zn(II) in model solutions of a well-characterized fulvic acid (Laurentian fulvic acid), freshwater samples from the Rideau River (Ottawa, Ontario), and freshwater samples from the Sudbury (Ontario) area were investigated by the competing ligand exchange method using Chelex 100 as the competing ligand and by inductively coupled plasma-mass spectrometry to measure the dissociation kinetics. The metal species were quantitatively characterized by the rate coefficient for the first-order dissociation of metal complex to free metal ion. This technique can be applied to almost all elements and represents an important advance in our ability to investigate the kinetic availability of metal species in the freshwater environment. The order of the lability of the metal complexes, Co(II) > Ni(II) > Cu(II) < Zn(II), follows the reverse order of the ligand field stabilization energy with the exception of Cu(II); the behavior of Cu(II) is also due to the Jahn-Teller effect, which shortens the equatorial bonds and lengthens the axial bonds of a tetragonally distorted Cu(II)-L6 complex. This study has demonstrated a relationship between the lability of metal-DOM complexes of the 3d transition metals in freshwaters and their d electron configuration. This is the first time that the importance of the d electron configuration on the lability of metal complexes in the freshwater environment has been demonstrated. The slow complexation kinetics of both Ni(II) and Cu(II) suggestthatthe usual equilibrium assumption for freshwaters may be invalid.     

Aging, cardiac proenkephalin mRNA and enkephalin peptides in the Fisher 344 rat

Cardiac proenkephalin (PENK) mRNA, methionine-enkephalin (ME) and leucine-enkephalin (LE) were determined from 2 days of age through senescence in Fisher 344 rats. Tissues were collected at 2 days, 2 weeks, 1, 2, 3, 7, 19, and either 22 or 27 months of age. Hearts were dissected, extracted and assayed for ME and LE by radioimmunoassay (RIA) or for PENK mRNA by Northern blot analysis with a cDNA probe. Relative left ventricular (LV) PENK mRNA was low in 2 day animals and increased slowly between 2 weeks and 3 months of age. LV PENK mRNA then rose five to six-fold between 3 and 27 months of age. LV ME measurements were high in neonatal animals, declined to a nadir during development and then rose again as the animals matured and advanced in age. The pattern for right ventricular (RV) ME was similar. Atrial ME, also high at 2 days, declined thereafter and remained low. LE measurements in LV, RV and the atria followed patterns similar to those described for ME. To evaluate for peptides contributed by cardiac nerves, 3, 7 and 22-month-old animals were acutely sympathectomized for 24 h with 6-hydroxydopamine. No decline in LV ME and LE was observed in the 6-hydroxydopamine treated animals. These data suggest several conclusions regarding myocardial enkephalinergic systems: (a) tissue enkephalin and PENK mRNA increase with advancing age, (b) tissue enkephalins may not strictly correlate with the relative abundance of PENK mRNA, and (c) most myocardial enkephalins are non-adrenergic in origin. The age-associated patterns in both PENK mRNA, ME and LE suggest that physiological, maturational or behavioral events between 3 and 7 months of age initiate the up-regulation and subsequent expansion of cardiac enkephalinergic systems.     

Analysis of damping characteristics of squeeze films under dynamic (cyclic) loading

This paper presents an analytical study of the damping characteristics of circular discs subjected to dynamic loads. Assuming a circular hydrostatic thrust bearing describing different geometrical configurations and surface texture irregularities (on both the macro- and micro-scales) and subjected to sinusoidal harmonic excitations, an analytical formulation to identify the oil film thickness variation as a function of damping loads is proposed. The Reynolds equation in the discretized form has been solved numerically using the tdma (Thomas Algorithm). Such a direct technique has proved to be reliable in solving similar problems and minimizing computational time compared with conventional iterative procedures. Compared to the performance of a flat and smooth circular disc, results indicated that the micro- and macro-surface undulations play a major role in dictating the squeeze action damping characteristics