Axisymmetric Rod Extrusion Through Smooth andPartially Rough Conical,Cosine, and Flat-Faced Circular Dies: Slip-Line Field Solutions Using Numerical Methods and Some Experiments

The numerical method of construction of axisymmetric slip-line fields is followed to obtain indirect type slip-line field solutions to axisymmetric rod extrusion using some smooth and partially rough conical, cosine, and flat-faced dies. A detailed computer program was written that calculates and plots both the slip-line field and the velocity field and carries out the entire procedure of estimating stresses and velocities in an iterative manner to reach either the desired or a reasonably valid solution, to each of these extrusion problems. The resultant values of the mean extrusion pressures are compared with those given by other authors and with some of the authors own experimental work in rod extrusion (tellurium lead) through conical dies of cone semi-angles, α varying from 11° to 26.5° and at reductions of 36–75%.     

坝内的坝

用混凝土充填的小型钢桩支承一座84a历史的平板坝坝内的，但完全与坝分离的加固混凝土体，即所谓的坝内坝。     

Optical properties and characterization of zinc nitride nanoneedles prepared from ball-milled Zn powders

Zinc nitride nanoneedles (ZNNs) with diameters at stem and tip parts as 200-300 nm and 30-70 nm respectively have been prepared by the nitridation of ball-milled zinc powders at 600 °C for 120 min under NH₃ gas environment. The structural, compositional and morphological characterizations of the product were conducted by X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy and transmission electron microscopy. From transmission spectrum data, an indirect band gap of 2.72 eV has been calculated for ZNNs whereas photoluminescence studies exhibited a strong UV excitonic mission band at 395 nm as well as two weak defect related blue emissions at 453 and 465 nm. A vapor-solid (VS) process based growth mechanism for the formation of ZNNs has also been discussed briefly.     

Investigation of active slip-systems in some body-centered cubic metals

Tensile tests were performed on high-purity W and Mo polycrystals at room temperature for a range of axial strain-rates 2.1 × 10⁻⁴–2.1 × 10⁻² s⁻¹. The critical resolved shear stress (CRSS) data was analyzed by using the analytical formulation for the strain-rate dependence of the CRSS derived in the kink-pair nucleation (KPN) model of flow stress in crystals with high intrinsic lattice friction. On evaluation of various microscopic slip-parameters of the model, the active slip-system in both W and Mo polycrystals was identified as {110}〈111〉. This is in good agreement with that deduced from the published data on the temperature dependence of the CRSS of these crystals as well as from the observed slip-lines on the deformed crystals reported in the literature. Moreover, the available data on the temperature dependence of the CRSS of Mo, Nb, Fe, V, and K crystals were also analyzed within the framework of the KPN model of flow stress. Peierls mechanism was found to be responsible for the CRSS of these metals; the active slip-systems in refractory metals Mo, Nb, Fe, and V were {110}〈111〉 and {211}〈111〉 whereas that in alkali metal K was {321}〈111〉.     

Effect of antistripping additives on environmental damage of bituminous mixtures

The main objective of this study was to investigate the effect of environmental damage (stripping) on the hot mix asphalt (HMA) creep behavior. To achieve this objective, 24 different HMA combinations using different mix parameters were evaluated for their resistance to static creep deformations. The mix parameters include: two types of asphalt cement, three types of aggregate gradation, and two types of antistripping additives (limestone dust and calcium stearate hydroxide). Marshall specimens were prepared at optimum asphalt contents and tested for static creep. Part of the prepared specimens were exposed to freezing–thawing conditioning according to AASHTO T283.     

Measurements of phantom scatter factors for small field sizes in high energy x rays

An alternate method to measure the phantom scatter factor in small fields is provided for high energy photon beams. The measurement technique is based on the density scaling theorem described by O'Connor [Phys. Med. Biol. 1, 352-369 (1957)]. The phantom scatter factor (Sp) is measured in balsa and cedar wood to give effective field sizes in 3 x 3 to 0.5 x 0.5 cm2 water. The extrapolated zero area phantom scatter factor from the average data of balsa and cedar is 0.45. This indicates that the variation of output is largely due to a sharp decrease in the phantom scatter factor for small field sizes.     

The U─Zr─C Ternary Phase Diagram above 2473 K

The U─Zr─C tertnary phase diagram is optimized by graphical and numerical curve fitting of self-consistent thermodynamic and phase diagram data reported in the literature. The system is described from 2473 to 3693 K using isothermal ternary phase diagrams. The solidus and liquidus curves of the U_xZr_1−xC_y solid solution were estimated from combined thermodynamic and phase diagram data. The solidus and liquidus curves in the ternary system were calculated using a modified form of a free-energy minimization method developed by Rudy and Chang. The calculated curves agree with experimental data.     

Increased height gain of children fed a high-protein diet during convalescence from shigellosis: a six-month follow-Up study

The impact of dietary supplementation on catch-up growth was evaluated in 69 malnourished children ages 24-60 mo after recovery from shigellosis. They were fed either a high-protein (HP) diet with 15% of energy as protein, or a standard-protein (SP) diet with 7.5% energy as protein, for 3 wk in a metabolic study ward. Children were followed up bi-weekly for 6 mo by trained health assistants when anthropometric measurements and information of any illness were collected. Thirty-one children in the HP group and 28 children in the SP group completed 6-mo follow-up. The increase in height (mean +/- SD) was 5.3 +/- 1.0 cm vs. 4.1 +/- 1.1 cm for HP and SP groups, respectively (P < 0.001), whereas increase in body weight was 1.39 +/- 0.58 and 1.29 +/- 0.72 kg for children fed HP and SP, respectively (P = 0.59). The proportion of children who were severely stunted (< -2 SD height-for-age) decreased from 45 to 29% in the HP group compared to 50 to 46% in the SP group (P < 0.05) at 6-mo follow-up. The number of diarrheal episodes per child tended to be lower in the HP vs. SP than in the SP group (1.9 vs. 2.3, P = 0.41). These results demonstrate that feeding an HP diet to the malnourished children during recovery from shigellosis enhanced linear growth with a modest reduction in diarrheal morbidity during the 6-mo follow-up period.