| 1. |
- Andersson, L-E, et al.
(författare)
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Some fundamental transmission properties of impedance transitions
- 1984
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Ingår i: Wave motion. - : Elsevier BV. - 0165-2125 .- 1878-433X. ; 6:4, s. 389-406
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Tidskriftsartikel (refereegranskat)abstract
- Reflection and transmission of waves by impedance transitions from a constant input to a constant output characteristic impedence are considered. Several fundamental properties are explored, primarily for impedance transitions with piece-wise constant characteristic impedance in an arbitrary number N of intervals of equal length. For example, the following properties are shown: (i) The relative momentum transmission depends only on the ratio of output to input characteristic impedance. (ii) For a given impedance transition there are at most, and generally exactly, 2N different transitions, including the original one, with identical transmission properties. (iii) For monotoneous impedance transitions the efficiency of energy transmission is minimized by one with an abrupt change in characteristic impedance. (iv) There exists an optimal impedance transition, with a certain antisymmetry, which maximizes the efficiency of energy transmission for a given incident wave of finite duration and energy. Several of the results can be extended to more general classes of impedence transitions. Simple illustrative examples are given.
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| 2. |
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| 3. |
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| 4. |
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| 5. |
- Grundevik, P, et al.
(författare)
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Hyperfine structure in the 6p5d configuration and isotope shifts in transitions between the 6s5d and the 6p5d configurations in Ba I
- 1982
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Ingår i: Zeitschrift für Physik A Hadrons and Nuclei. - 0939-7922. ; 306:3, s. 195-209
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Tidskriftsartikel (refereegranskat)abstract
- High-resolution laser fluorescence spectroscopy, using a single-mode dye laser acting on a collimated atomic beam, has been performed to determine the hyperfine-structure (hfs) constants in six states of the 6p 5d configuration of135Ba and137Ba. Isotope shifts (IS) for eleven transitions between the 6s 5d and the 6p 5d configurations have also been measured. From an analysis of the energy levels, intermediate angular wavefunctions have been deduced. The wavefunctions are used to evaluate experimental hyperfine parameters from the experimental hfs constants. The parameters are, for the magnetic-dipole interaction compared with theoretical values, and for the electricquadrupole interaction used to estimate the nuclear quadrupole moments for the odd isotopes.
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| 6. |
- Lagerkvist, L., et al.
(författare)
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Effect of contributions from bending in evaluation of axial strain in rods with circular cross-section
- 1983
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Ingår i: Journal of Strain Analysis for Engineering Design. - 0309-3247 .- 2041-3130. ; 18:1, s. 77-79
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Tidskriftsartikel (refereegranskat)abstract
- Contributions from bending to the evaluated axial strain in an elastic rod are commonly suppressed by forming half the sum of measured surface strains at diametrically opposite positions. A simple method is presented which gives a useful estimation of the bending suppression (the ratio of the bending strain to the absolute value of the evaluated axial strain when a rod is subject to bending only) from (i) optically measured mis-positioning and (ii) estimated differences between the gauge constants for the two strain gauges. Good agreement is obtained with results obtained from strain measurements on a rod loaded in bending
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| 7. |
- Lagerkvist, L., et al.
(författare)
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Mechanical impedance gauge based on measurement of strains on a vibrating rod
- 1982
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Ingår i: Journal of Sound and Vibration. - 0022-460X .- 1095-8568. ; 80:3, s. 389-399
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Tidskriftsartikel (refereegranskat)abstract
- An impedance gage based on measurement of strains at two different cross-sections of a vibrating rod is analyzed and tested. The gage rod, which may have variable characteristic impedance, is in contact with the object at one end and is driven by a harmonic vibrator at the other end. For conical and cylindrical rods explicit relations between point impedance and measured strains are derived. For a cylindrical gage rod of steel with length 800 mm, diameter 10 mm, and distance between strain gages 250 mm a fair agreement was generally obtained between experimental and theoretical point impedances of cylindrical test objects in the frequency range 50 Hz to 1. 7 kHz. Significant improvements in accuracy over that of the tested prototype are expected to be feasible
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| 8. |
- Lundberg, Bengt, et al.
(författare)
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Influence of geometrical design on the efficiency of a simple down-the-hole percussive drill
- 1986
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Ingår i: International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts. - : Elsevier BV. - 0148-9062 .- 1879-2073. ; 23:3, s. 281-287
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Tidskriftsartikel (refereegranskat)abstract
- In the present investigation, the simulation program DTH-SIM is used to determine the efficiency of a simple down-the-hole percussive drill, which has the main features of a practical design. The efficiency is obtained as a function of the same dimensionless parameters as in a preceding study of two additional parameters which represent the characteristic impedance and the length of the head of the bit. Several results obtained here for non-uniform bits differ considerably from those established previously for uniform bits
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| 9. |
- Lundberg, C, et al.
(författare)
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Inflammatory reaction in an experimental model of open wounds in the rat. The role of polymorphonuclear leukocytes.
- 1984
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Ingår i: Laboratory Investigation. - 0023-6837 .- 1530-0307. ; 50:6, s. 726-32
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Tidskriftsartikel (refereegranskat)abstract
- The accumulation of polymorphonuclear leukocytes (PMNLs) and the concentration of prostaglandin E2 in full thickness open skin wounds, created in the back of the rat, were studied. The quantity of PMNLs in the granulation tissue, assessed by analysis of wound exudate myeloperoxidase activity, increased from 0.45 units/ml on day 1 after wounding to 0.8 units/ml on day 2 and then remained constant throughout the 5 days of observation. The prostaglandin E2 concentration in wound exudate was measured by radioimmunoassay increased progressively from 70 ng/ml on day 1 to 290 ng/ml on day 5. The lack of correlation between these two variables indicates that PMNLs were not the major source of prostaglandin E2. To study the relation between PMNL accumulation, blood flow, and albumin extravasation in the granulation tissue, rats were treated with an antineutrophil serum. This resulted in an 83% decrease in circulating PMNLs and a 61% decrease in granulation tissue myeloperoxidase activity on the 5th day, as compared with rats treated with normal rabbit serum. No relationship was observed between myeloperoxidase activity and blood flow (r = 0.37) or between myeloperoxidase activity and albumin extravasation (r = -0.34) when absolute values were compared. However, when interindividual variation in the absolute levels of the variable measured was eliminated, by calculating in each rat a left to right wound ratio, good correlations (r = 0.81 and r = 0.65, respectively) were found. It is suggested that blood flow and albumin extravasation in the granulation tissue are influenced by local PMNL accumulation.
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| 10. |
- Lundberg, C, et al.
(författare)
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The inflammatory reaction in healing wounds : the role of polymorphonuclear leucocytes.
- 1984
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Ingår i: International journal on tissue reactions. - 0250-0868. ; 6:6, s. 477-83
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Tidskriftsartikel (refereegranskat)abstract
- The inflammatory process in granulation tissue in full-thickness skin wounds was studied and the role of polymorphonuclear leucocytes (PMNLs) in this process evaluated in an experimental model in the rat. The number of PMNLs in the wound, assessed by determination of the PMNL-specific enzyme myeloperoxidase (MPO) activity in wound exudate, increased from 0.45 U/ml on day 1 after wounding to 0.8 U/ml on day 2, and then remained constant throughout the five days of observation. The concentration of prostaglandin E2 (PGE2) in wound exudate increased progressively from 70 ng/ml on day 1 to 290 ng/ml on day 5. The lack of correlation between these two variables indicated that PMNLs were not the major source of PGE2. Blood flow and albumin extravasation in the granulation tissue were measured, and the relation between these two variables and PMNL accumulation was studied. Rats were rendered neutropenic with an antineutrophil serum, resulting in an 83% decrease in circulating PMNLs and a 61% decrease in granulation tissue MPO activity on day 5, as compared with rats treated with normal rabbit serum. These reductions did not, however, affect either blood flow or albumin extravasation, and no correlation was observed; but when inter-individual variations in the absolute levels of the variables measured were eliminated by calculating in each rat a left-to-right wound ratio, PMNL accumulation correlated well to both blood flow (R = 0.81) and albumin extravasation (R = 0.65). It is suggested that blood flow and albumin extravasation in the granulation tissue are influenced by local PMNL accumulation and, further, that the inflammatory response varies considerably between one animal and another.
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