Importance of Tool Configuration in Incremental Sheet Metal Forming of Difficult to Form Materials Using Electro-Plasticity

Titanium alloys possess low formability and high flows stresses and are difficult to form without using thermal aid to reduce the flow stress. It has been observed that high density electric pulse aide plastic deformation through electron-dislocation interaction and this phenomenon is termed as electro-plasticity where the reduction in flow stress is not due to resistive heating. Present work makes use of high density DC pulses to deform a Ti alloy using incremental sheet metal forming (ISMF) to emphasize the importance of tool configuration to minimize the resistive heating. Results indicate that the tool configuration plays a significant role to reduce the effect of resistive heating and to enhance effectiveness of electro-plastic effect

Importance of Tool Configuration in Incremental Sheet Metal Forming of Difficult to Form Materials Using Electro-Plasticity

Titanium alloys possess low formability and high flows stresses and are difficult to form without using thermal aid to reduce the flow stress. It has been observed that high density electric pulse aide plastic deformation through electron-dislocation interaction and this phenomenon is termed as electro-plasticity where the reduction in flow stress is not due to resistive heating. Present work makes use of high density DC pulses to deform a Ti alloy using incremental sheet metal forming (ISMF) to emphasize the importance of tool configuration to minimize the resistive heating. Results indicate that the tool configuration plays a significant role to reduce the effect of resistive heating and to enhance effectiveness of electro-plastic effect

Evolution of Density Perturbations in a Cylindrical Molecular Cloud Using Smoothed Particle Hydrodynamics

Molecular clouds have a hierarchical structure from few tens of parsecs for giants to few tenth of a parsec for proto-stellar cores. Nowadays, our observational techniques are so advanced that it has become possible to detect the small-scale substructures inside the molecular cores. The question that arises is how these small condensations are formed. In the present research, we study the effect of ambipolar diffusion heating on the ubiquitous perturbations in a molecular cloud and investigate the possibility of converting them to dense substructures. For this purpose, a small azimuthal perturbation is implemented on the density of an axisymmetric two-dimensional cylindrical cloud, and its evolution is simulated bythe technique of two-fluid smoothed particle hydrodynamics. Theself-gravity is not included and the initial state has uniformdensity, temperature and magnetic field, parallel to theaxis of cylinder. In addition, all perturbed quantities are assumed todepend onlyon azimuth angle and time. Computer experiments show that if theambipolar diffusion heating is ignored, the perturbation willbe dispersed over the time. Including the heating due to ambipolardiffusion heats the matter in regions adjacent to the perturbation, thus,leading to the transfer of matter into the perturbed area. In this case, the density of perturbations can be increased. Also, the results ofsimulations show that an increase of the initial magnetic pressureleads to the intensification of difference between density ofperturbations and their surroundings (i.e. increasing of density contrast). This effect is due to the direct relationship of the drift velocity to the intensity of the magnetic field and its gradient. Simulations with different initial uniform densities show that the growth of relative density contrast is more clear with a special density. This result can be explained by the intensification of thermal instability in this special density

Current Tests for Tubal Patency: Their Study and Comparison

Two hundred patients have been reviewed in whom culdoscopy or laparoscopy was performed for infertility study. During these two procedures, methylene blue was injected through an endocervical cannula for detection of tubal patency under direct visualization. When compared with 89 patients tested by utero-tubal insufflation and hystero-salpingography, results indicated that direct visualization of the tubes and dye hydrotubation appears to be the most reliable method. HSG proved to be the second most reliable method with a failure rate of 19.2%. The least accurate procedure in this study was UTI with CO2 gas, where the failure rate was 24.7%. The latter lest, however, is the most efficient one for detecting tubal spasm

Are disaggregate industrial returns sensitive to economic policy uncertainty

© 2019 Elsevier B.V. This study investigates the impact of economic policy uncertainty on disaggregate US sector based returns. Our work is motivated by the presence of non-linear relationship between US economic policy uncertainty and equity returns of sampled US sectors. The paper uses weekly data from January 1995 to December 2015 for all the return indices and economic policy uncertainty data mainly based on policy issues, provision set for the US federal tax code and disagreement among economic forecasters. Our results indicate that information technology, utilities, industrial and telecommunication sectors remain insensitive to changes in the US economic policy uncertainty. However, financial and the consumer discretionary sectors show significant long run asymmetric relationship with the EPU.Accepted versio

Asymptotic Behaviour of the Proper Length and Volume of the Schwarzschild Singularity

Though popular presentations give the Schwarzschild singularity as a point it is known that it is spacelike and not timelike. Thus it has a "length" and is not a "point". In fact, its length must necessarily be infinite. It has been proved that the proper length of the Qadir-Wheeler suture model goes to infinity [1], while its proper volume shrinks to zero, and the asymptotic behaviour of the length and volume have been calculated. That model consists of two Friedmann sections connected by a Schwarzschild "suture". The question arises whether a similar analysis could provide the asymptotic behaviour of the Schwarzschild black hole near the singularity. It is proved here that, unlike the behaviour for the suture model, for the Schwarzschild essential singularity $\Delta s$ $\thicksim$ $K^{1/3}\ln K$ and $V\thicksim$ $K^{-1}\ln K$, where $K$ is the mean extrinsic curvature, or the York time.Comment: 13 pages, 1 figur

Lithium Dendrite Growth Control Using Local Temperature Variation

We have quantified lithium dendrite growth in an optically accessible symmetric Li-metal cell, charged under imposed temperatures on the electrode surface. We have found that the dendrite length measure is reduced up to 43% upon increasing anodic temperature of about 50°C. We have deduced that imposing higher temperature on the electrode surface will augment the reduction rate relative to dendritic peaks and therefore lithium holes can draw near with the sharp deposited tips. We have addressed this mechanism via fundamentals of electrochemical transport

Note on flat foliations of spherically symmetric spacetimes

It is known that spherically symmetric spacetimes admit flat spacelike foliations. We point out a simple method of seeing this result via the Hamiltonian constraints of general relativity. The method yields explicit formulas for the extrinsic curvatures of the slicings.Comment: 4 pages, to appear in PRD, reference added, typos correcte