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[en] The transformation from short-range - long-range order in alloy 242, a nominal Ni-25Mo-8Cr (in wt pct) alloy, during both continuous heating and cooling and isothermal holding at temperatures between 550 and 750 C is reported using dilatometry and microhardness measurements, and optical and transmission electron microscopy. The long-range to short-range order transformation temperature was observed to increase with an increase in the degree of prior order. Aging below the transformation temperature led to considerable hardening; this hardening was associated with the formation of a very high volume fraction of Ni2Mo domains/precipitates. On aging at 700 C and below, the hardness initially increases and then levels off, with no evidence of overaging for times to 2000 hs. The role of both short- and long-range order on the transformation temperature, thermal expansion, and hardening behavior and the mechanisms of transformation from short-range to long-range order were established and are discussed. 17 refs
[en] Cream-filled cakes are tested by passing a #betta#-ray from a #betta#-particle source to a detector and checking the #betta#-particle count to indicate if the cakes have been correctly filled with cream. The presence of a cake to be tested is sensed by an optical detector and incorrectly filled cakes are removed by a plunger. (author)
[en] Shape memory alloy (SMA) springs have been used as actuators in many applications although their use in the vibration control area is very recent. Since shape memory alloys differ from conventional alloy materials in many ways, the traditional design approach for springs is not completely suitable for designing SMA springs. Some vibration control concepts utilizing unique characteristics of SMA's will be presented in this paper.A dynamic vibration absorber (DVA) using shape memory alloy (SMA) actuator is developed for attenuation of vibration in a cantilever beam. The design procedure of the DVA is presented. The system consists of a cantilever beam which is considered to generate the real-time vibration using shaker. A SMA spring is used with a mass attached to its end. The stiffness of the SMA spring is dynamically varied in such a way to attenuate the vibration. Both simulation and experimentation are carried out using PID controller. The experiments were carried out by interfacing the experimental setup with a computer using LabVIEW software, Data acquisition and control are implemented using a PCI data acquisition card. Standard PID controllers have been used to control the vibration of the beam. Experimental results are used to demonstrate the effectiveness of the controllers designed and the usefulness of the proposed test platform by exciting the structure at resonance. In experimental setup, an accelerometer is used to measure the vibration which is fed to computer and correspondingly the SMA spring is actuated to change its stiffness to control the vibration. The results obtained illustrate that the developed DVA using SMA actuator is very effective in reducing structural response and have great potential to be an active vibration control medium.
[en] Aim of the study: The aim of the present study was to understatnd the forest composition, structure, diversity and regeneration potential along altitudinal gradient. Area of study: The study was carried out in Dhanaulti forest which falls under temperate region of Garhwal Himalaya in Uttarakhand state, India. Material and Methods: Vegetation analysis was carried out using 10 quadrats at each altitude using a quadrate size of 10×10 m2. In each quadrate, categories of trees >30 cm cbh were considered as trees, 10-30cm cbh as saplings and <10 cm cbh as seedlings. The data were quantitatively analyzed. Main results: In upper and middle altitudes, Cedrus deodara was reported dominant tree whereas, in lower altitude Quercus leucotrichophora was reported dominant. Tree density was highest in lower altitude which reduced middle and upper altitudes whereas, total basal cover increased with increasing altitude. The increasing total basal cover with altitude could be because of the presence of Cedrus deodara trees having higher girth classes. In tree, sapling and seedling layers, diversity (H) and equitabiltiy (EC) decreased with increasing altitude. However, concentrations of dominace (CD) and beta diversity (BD have shown reverse trend with H and EC which increased with increasing altitudes, in each layer of tree, sapling and seedling. The distribution pattern of most species in all layers of trees, saplings and seedlings was contagious. The regeneration potential of the species has shown that some of the species in the absence of tree layer are still regenerating particularly, Rhododendron arboreum, Benthamidia capitata, Neolitsea pallens etc. It indicates that most of the species are shifting upward as they are getting suitable conditions. Research highlights: Altitude influence species composition, diversity and regeneration potential of species. (Author)
[en] The most widely used method of thermal oil recovery is by injecting steam into the reservoir. A well-designed steam injection project is very efficient in recovering oil, however its applicability is limited in many situations. Simulation studies and field experience has shown that for low injectivity reservoirs, small thickness of the oil-bearing zone, and reservoir heterogeneity limits the performance of steam injection. This paper discusses alternative methods of transferring heat to heavy oil reservoirs, based on electromagnetic energy. They present a detailed analysis of low frequency electric resistive (ohmic) heating and higher frequency electromagnetic heating (radio and microwave frequency). They show the applicability of electromagnetic heating in two example reservoirs. The first reservoir model has thin sand zones separated by impermeable shale layers, and very viscous oil. They model preheating the reservoir with low frequency current using two horizontal electrodes, before injecting steam. The second reservoir model has very low permeability and moderately viscous oil. In this case they use a high frequency microwave antenna located near the producing well as the heat source. Simulation results presented in this paper show that in some cases, electromagnetic heating may be a good alternative to steam injection or maybe used in combination with steam to improve heavy oil production. They identify the parameters which are critical in electromagnetic heating. They also discuss past field applications of electromagnetic heating including technical challenges and limitations
[en] FeCoV/Ti multilayers are investigated in order to study perpendicular magnetic anisotropy, variation of saturation magnetization, remanence, coercivity and structural properties. Five samples with tTi=1.04 nm and tFeCoV=0.89-4.47 nm are prepared by DC magnetron sputtering. X-ray diffraction measurements carried out on the samples show a strong FeCoV(1 1 0) texture for larger tFeCoV. The grain size determined from the FeCoV(1 1 0) peaks displays a decreasing trend with decreasing tFeCoV indicating that the grain size is mainly determined by the tFeCoV. We have performed magnetic hysteresis measurements in order to investigate various magnetic properties. The interface/surface and volume anisotropy constants determined from the measurements are Ks=0.826 mJ/m2 and Kv=-1.84 MJ/m3, respectively. The data analysis indicates that the samples may have their easy direction of magnetization perpendicular to the film plane for tFeCoV<0.89 nm.The saturation magnetization is observed to decrease with decreasing tFeCoV and from a plot of MstFeCoV vs. tFeCoV we have determined a dead layer thickness of 0.33 nm at the FeCoV interfaces. The variation of coercivity and remanence with tFeCoV may be due to both random anisotropy and superparamagnetism. The decrease in remanence with decreasing tFeCoV can also be attributed to the progressive change of the easy direction of magnetization away from the film plane
[en] 5-Aminosalicylic acid (5ASA), a prescribed drug for ulcerative colitis, is a potent scavenger of oxygen-derived free radicals. The present study was undertaken to ascertain its ability to protect against radiation-induced damage. The drug dose-dependent effect, optimum time of drug administration and radiation dose-dependent effect (0-4 Gy) on in vivo radiation protection against micronuclei induction in polychromatic erythrocytes (PCE) and normochromatic erythrocytes (NCE) were studied in the bone marrow of mice. Intraperitoneal injection of 10-125 mg/kg of the drug 30 min before whole body irradiation with 3 Gy produced a significant reduction in the frequency of micronucleated erythrocytes at 24 h after exposure. The optimum dose for protection without drug toxicity was 25 mg/kg body weight. Injection of 25 mg/kg of the drug 60 or 30 min before or within 15 min after 3 Gy whole body γ-irradiation resulted in a significant decrease in the radiation-induced PCE and NCE with micronuclei (MPCE and MNCE) and an increase in the ratio of PCE to NCE (P/N), at 24 h post-irradiation. Maximum effect was seen when the drug was administered 30 min before irradiation. Therefore, to study the radiation dose-response, mice were pre-treated with 25 mg/kg of 5ASA 30 min before 1-4 Gy of γ-irradiation. Radiation increased the MN frequency linearly (r2=0.99) with dose. Pre-treatment with 5ASA significantly reduced the MN counts to 40-50% of the radiation (RT) alone values, giving a dose modification factor (DMF) of 2.02 (MPCE) and 2.53 (MNCE). Irradiation resulted in a dose-dependent decline in the P/N ratio at all the doses of radiation studied. 5ASA produced a significant increase in the P/N ratio from that of irradiated controls, at all doses of radiations tested. These results show that 5ASA protect mice against radiation-induced MN formation and mitotic arrest
[en] Rn222 (radon) from Ra226 (radium) and two other natural isotopes of Rn219 (actinon) and Rn220 (thoron) are present in any rock formation in the soil, in groundwater and in the atmosphere. The inert gases, such as radon, are poorly affected by chemical equilibration processes and are often considered in earthquake prediction because of the high mobility characteristics, high natural production rate and relative low price of automatic monitoring analytical equipment. This study deals with the monitoring of radon in groundwater wells, groundwater table depth and water temperature for the year 1997. The daily oscillations of radon levels have been recorded with instantaneous technique using ZnS(Ag) detector from the borehole at Amritsar, India (31 deg. 35'N, 74 deg. 56'E). Significant increases in radon concentration of groundwater and water level have been observed which are correlated to the seismic events which occurred in Northern India during the period of study. The correlation between the radon levels and water table depth as well as water temperature is also discussed
[en] The coating of black copper oxide on copper developed through chemical oxidation reveals a high solar absorptance and low thermal emittance with a temperature stability up to 270 degC. The coating has potential for application as selective absorbers for solar energy conversion. The coating is resistant to natural weathering. (author). 1 tab
[en] A modified tool design is proposed which helps in drilling holes without any central core, and also enables the effective removal of the debris particles. Experiments were conducted on AISI D2 Steel using copper electrode as tool in both conventional EDM and dry EDM processes and the performance of both processes is compared. Experiments were designed using Taguchi's L27 orthogonal array. Discharge current (I), gap voltage (V), pulse on time (T_O_N), gas pressure (P) and tool rotational speed (N) were chosen as the various input parameters, and their effect on the material removal rate (MRR), surface roughness (SR), surface morphology, microstructure and elemental composition of the machined surface is analyzed. The experimental results show better surface characteristics in the surface machined under dry EDM process.