Survey of electrical resistivity measurements on 8 additional pure metals in the temperature range 0 to 273 K

Electrical resistivity measurements on pure metals in temperature range 0 to 273

Study of a Proposed Infrared Horizon Scanner for Use in Space-Orientation Control Systems

An attitude-sensing device for space vehicles which detects the thermal radiation discontinuity at opposite horizons of a planetary body to produce an attitude error signal is described. The planetary body may be the Earth, its Moon, Mars, or Venus. The sensor is expected to have an accuracy of 0.25 degrees for the Earth, a long continuous operating lifetime, a wide altitude range, a wide capture capability, and an inherent ability to produce signals indicating vehicle altitude. An experimental model incorporating many of the features of the proposed sensor indicates that the proposed sensor will be low in weight, volume, and power consumption. The sensor's altitude range, accuracy, lifetime, and sensitivity to radiation from the Moon and planets are discussed

A Modified Precision Barometer.

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Vectors of subsurface stormflow in a layered hillslope during runoff initiation

The focus is the experimental assessment of in-situ flow vectors in a hillslope soil. We selected a 100 m² trenched hillslope study site. During prescribed sprinkling an obliquely installed TDR wave-guide provides for the velocity of the wetting front in its direction. A triplet of wave-guides mounted along the sides of an hypothetical tetrahedron, with its peak pointing down, produces a three-dimensional vector of the wetting front. The method is based on the passing of wetting fronts. We analysed 34 vectors along the hillslope at distributed locations and at soil depths from 11 cm (representing top soil) to 40 cm (close to bedrock interface). The mean values resulted as follows <i><b>v</b>_x</i>=16.1 mm min^-1, <i><b>v</b>_y</i>=-0.2 mm min^-1, and <i><b>v</b>_z</i>=11.9 mm min^-1. The velocity vectors of the wetting fronts were generally gravity dominated and downslope orientated. Downslope direction (x-axis) dominated close to bedrock, whereas no preference between vertical and downslope direction was found in vectors close to the surface. The velocities along the contours (y-axis) varied widely. The Kruskal-Wallis tests indicated that the different upslope sprinkling areas had no influence on the orientation of the vectors. Vectors of volume flux density were also calculated for each triplet. The lateral velocities of the vector approach are compared with subsurface stromflow collected at the downhill end of the slope. Velocities were 25-140 times slower than lateral saturated tracer movements on top of the bedrock. Beside other points, we conclude that this method is restricted to non-complex substrate (skeleton or portion of big stones)

Restoration of Native Leg Length After Opening-Wedge High Tibial Osteotomy: An Intraindividual Analysis

BACKGROUND Opening-wedge high tibial osteotomy (OWHTO) has been shown to significantly increase leg length, especially in patients with large varus deformity. Thus, the current literature recommends closing-wedge high tibial osteotomy to correct malalignment in these patients to prevent postoperative leg length discrepancy. However, potential preoperative leg length discrepancy has not been considered yet. HYPOTHESIS It was hypothesized that patients have a decreased preoperative length of the involved leg compared with the contralateral side and that OWHTO would subsequently restore native leg length. STUDY DESIGN Case series; Level of evidence, 4. METHODS Included were 67 patients who underwent OWHTO for unilateral medial compartment knee osteoarthritis and who received full leg length assessment pre- and postoperatively. Patients with varus or valgus deformity (>3°) of the contralateral side were excluded. A musculoskeletal radiologist assessed imaging for the mechanical axis, full leg length, and tibial length of the involved and contralateral lower extremity. Statistical analysis determined the pre- and postoperative leg length discrepancy and the influence of the mechanical axis. RESULTS Most patients (62.7%) had a decreased length of the involved leg, with a mean preoperative mechanical axis of 5.0° ± 2.9°. Length discrepancy averaged -2.2 ± 5.8 mm, indicating a shortened involved extremity (P = .003). OWHTO significantly increased the mean lengths of the tibia and lower limb by 3.6 ± 2.9 and 4.4 ± 4.7 mm (P < .001), leading to a postoperative tibial and full leg length discrepancy of 2.8 ± 4.3 mm and 2.2 ± 7.3 mm (P < .001 and P = .017, respectively). Preoperative leg length discrepancy was significantly correlated with the preoperative mechanical axis of the involved limb (r = 0.292; P = .016), and the amount of correction was significantly associated with leg lengthening after OWHTO (r = 0.319; P = .009). Patients with a varus deformity of ≥6.5° (n = 14) had a preoperative length discrepancy of -4.5 ± 1.6 mm (P < .001) that was reduced to 1.8 ± 3.5 mm (P = .08). CONCLUSION Patients undergoing OWHTO have a preoperative leg length discrepancy that is directly associated with the varus deformity of the involved extremity. As OWHTO significantly increases leg length, restoration of native leg length can be achieved particularly in patients with large varus deformity

Association of Subchondral Changes With Age and Clinical Outcome in Patients With Osteochondral Fractures in the Knee: MRI Analysis at 1 to 10 Years Postoperatively

Background Predictive factors influencing outcomes after surgical fixation of osteochondral fractures (OCFs) in the knee, particularly time between injury and surgery, have not been determined. Purpose To report imaging and clinical outcomes after OCF fixation and to assess the association between clinical scores and patient characteristics, lesion morphology, and appearance on magnetic resonance imaging (MRI) scans. Study Design Case series; Level of evidence, 4. Methods We assessed the clinical and imaging outcomes of 19 patients after screw fixation for OCFs in the knee at a minimum follow-up of 1 year. Patient characteristics, lesion morphology, and time from trauma to surgery were reviewed for each patient. At final follow-up, patients completed a 100-point visual analog scale (VAS) for pain, Tegner activity scale, Knee injury and Osteoarthritis Outcome Score (KOOS), and patient satisfaction survey. Postoperative MRI scans were assessed using the MOCART (magnetic resonance observation of cartilage repair tissue), Osteochondral Allograft MRI Scoring System, and bone marrow edema (BME) size. Results The mean patient age at surgery was 21.3 ± 11.4 years, and the median time from trauma to surgery was 10 days (range, 0-143 days). The refixed OCF fragment failed in 1 (5.3%) patient on the lateral condyle at 15 months postoperatively. The mean follow-up for the remaining 18 patients was 4.7 ± 3.2 years, and postoperative outcomes were as follows: VAS pain score, 9.5 ± 17.9; Tegner score, 4.8 ± 2.3; KOOS-Pain, 85.9 ± 17.6, KOOS-Symptoms, 76.4 ± 16.1; KOOS-Activities of Daily Living, 90.3 ± 19.0; KOOS-Sport, 74.4 ± 25.4; and KOOS-Quality of Life, 55.9 ± 24.7. Overall, 84.2% were satisfied or very satisfied with outcomes. Patient age was significantly associated with KOOS subscale scores and subchondral imaging parameters including BME and presence of subchondral cysts, which in turn were the only imaging variables linked to clinical outcomes (P < .05). Time from injury to surgery was not correlated with clinical or imaging outcomes. Conclusion Fixation of OCFs yielded acceptable clinical and imaging outcomes at a mean 5-year follow-up with seemingly little influence of delayed surgical treatment. Postoperative subchondral changes were significantly associated with clinical outcomes and were linked to patient age at surgery

Fatigue analysis-based numerical design of stamping tools made of cast iron

This work concerns stress and fatigue analysis of stamping tools made of cast iron with an essentially pearlitic matrix and containing foundry defects. Our approach consists at first, in coupling the stamping numerical processing simulations and structure analysis in order to improve the tool stiffness geometry for minimizing the stress state and optimizing their fatigue lifetime. The method consists in simulating the stamping process by considering the tool as a perfect rigid body. The estimated contact pressure is then used as boundary condition for FEM structure loading analysis of the tool. The result of this analysis is compared with the critical stress limit depending on the automotive model. The acceptance of this test allows calculating the fatigue lifetime of the critical zone by using the S–N curve of corresponding load ratio. If the prescribed tool life requirements are not satisfied, then the critical region of the tool is redesigned and the whole simulation procedures are reactivated. This method is applied for a cast iron EN-GJS-600-3. The stress-failure (S–N) curves for this material is determined at room temperature under push pull loading with different load ratios R0σmin/σmax0−2, R0−1 and R00.1. The effects of the foundry defects are determined by SEM observations of crack initiation sites. Their presence in tested specimens is associated with a reduction of fatigue lifetime by a factor of 2. However, the effect of the load ratio is more important

Drainage vernässter Waldböden infolge kurzzeitiger Starkniederschläge im Flysch-Gürtel der Voralpen

Anhand von Beregnungsexperimenten wurden in vernässten Böden volumetrische Wassergehalte während der Drainage analysiert. Aufgrund des Verlaufs der Wassergehaltsabnahme konnte auf die Fliessrichtung des Bodenwassers geschlossen werden. Morphologische Horizonte gaben gewisse Hinweise auf Drainageprozesse. Vertikaler Ausfluss war grundsätzlich auf nicht hydromorphe Horizonte beschränkt. Da vernässte Unterböden nicht oder lateral drainierten, erfolgte die Entwässerung des gesamten Bodens lateral. Die vorgestellte Methode erlaubt, Prozesse auf Profilskala (vertikaler Fluss) mit Vorgängen auf der Hangskala (lateraler Fluss) in Verbindung zu bringen