Prestressing of compression springs

A scheme of force variation during the compression of a spring in both elastic and elastic-plastic state is presented. For the elastic state it has been found that equivalent load increments occur with equivalent deflection increments. In the elastic-plastic state equivalent load increments correspond to higher deflection increments. Prestressing the spring increases the range of the elastic deformation of a spring. Equations for the determination of torsional moment during prestressing and relationships of total non-dilatational strain versus elastic strain and radii of elastic zone are also presented. The effect of characteristic spring dimensions and non-dilatational strain on spring deflection has been determined. A nomogram for the determination of the resultant equivalent strain as a function of external load, also considering residual stress distribution, has as well been elaborated.     

Drawing of square twisted wire

The shape of the deformation zone during drawing of square twisted wires is described in this paper. The condition of the stable deformation of the wire is formulated. This condition is satisfied by the constant value of the pitch of the helical surface of the die. The work focuses on the investigation of the influence of the die cone angle on the drawing parameters, in particular on the drawing stress.     

A computational framework for scale‐bridging in multi‐scale simulations

A computational framework for scale‐bridging in multi‐scale simulations is presented. The framework enables seamless combination of at‐scale models into highly dynamic hierarchies to build a multi‐scale model. Its centerpiece is formulated as a standalone module capable of fully asynchronous operation. We assess its feasibility and performance for a two‐scale model applied to two challenging test problems from impact physics. We find that the computational cost associated with using the framework may, as expected, become substantial. However, the framework has the ability of effortlessly combining at‐scale models to render complex multi‐scale models. The main source of the computational inefficiency of the framework is related to poor load balancing of the lower‐scale model evaluation We demonstrate that the load balancing can be efficiently addressed by recourse to conventional load‐balancing strategies. Copyright © 2016 John Wiley & Sons, Ltd.     

Electron transport and detection of terahertz radiation in a GaN/AlGaN submicrometer field-effect transistor

Electron transport and photoresponse in the terahertz range in a GaN/AlGaN field-effect transistor with the submicrometer gate (0.25 μm) and two-dimensional electron gas in the channel (the electron concentration n _s = 5 × 10¹² cm^?2) were studied at 4.2 K. The charge-carrier mobility in the transistor’s channel μ = 3500 cm²/(V s) was determined from the dependence of the conductance on magnetic field. It is found that the dependence of photovoltage at the radiation frequency f = 574 GHz on the gate voltage (i.e., on the concentration of two-dimensional electrons) features a characteristic maximum, which is related to a resonance response of the subgate plasma in the transistor channel.     

Modification of physicochemical properties of actin filaments suppresses cell fragmentation in the execution phase of staurosporine-induced apoptotic processes

Effects of jasplakinolide (JSP), a stabilizer of F-actin, and latrunculin A (LTA), a destabilizer of F-actin, on a series of events occurring in the execution phase of staurosporine (STS)-induced apoptotic processes were studied using human osteosarcoma 143B cells. Time-dependent apparent increases of the population of cells with collapsed membrane potential of mitochondria (Delta Psi(m)) caused by STS treatment were not due to actual decreases in the Delta Psi(m) per cell, but due to the fragmentation of cells resulting in decreases in the number of active mitochondria per cell. Decreases in the Delta Psi(m) in fragmented cells occurred late in the execution phase. Both JSP and LAT failed to prevent STS-induced release of cytochrome c from mitochondria followed by the activation of caspases 3 and 9, the cleavage of poly (ADP-ribose) polymerase (PARP) and apoptotic nuclear fragmentation. However, both drugs prevented STS-induced apoptotic cell fragmentation and decreases in the Delta Psi(m). These results indicate that physicochemical states of actin filaments play a certain role in the execution phase of STS-induced apoptotic processes.     

Narrowband to broadband conversion of Landsat TM glacier albedos

In this paper we present an empirical relationship between the broadband glacier albedo (alpha) and the narrowband glacier albedos in Landsat TM bands 2 and 4 (alpha2 and alpha4, respectively). The relationship was established on the basis of multiple linear regression analysis of 112 ground-based simultaneous measurements of alpha, alpha2 and alpha4 made at 32 sites on the tongue of the Morteratschgletscher, Switzerland. The measurements were carried out over a representative set of glacier surface types ranging from completely debris-covered glacier ice (alpha=0.08)to dry snow (alpha=0.86). The regression model explains more than 99% of the variance of the broadband albedo and the root-mean-square value of the residuals is only 0.009. The relationship enables users of Landsat TM data to make an accurate estimate of the broadband albedo on the basis of narrowband albedos without having to classify the glacier surface.     

Effect of transfer on droplet size in liquid-liquid dispersions

Mean droplet diameter of the dispersed phase in pulsed plate extraction columns was measured for binary and ternary systems. A change in the droplet size in the presence of solute, dependent on such factors as the direction of mass transfer, droplet size in the binary system, radio of diffusion coefficients, viscosity of the continuous phase, interfacial tension and driving force for extraction was observed. Two new empirical correlations of mean droplet sizes in mass transfer conditions are proposed. These correlations have been successfully applied to other extraction columns.     

A call to arms for task parallelism in multi‐scale materials modeling

Simulations based on multi‐scale material models enabled by adaptive sampling have demonstrated speedup factors exceeding an order of magnitude. The use of these methods in parallel computing is hampered by dynamic load imbalance, with load imbalance measurably reducing the achieved speedup. Here we discuss these issues in the context of task parallelism, showing results achieved to date and discussing possibilities for further improvement. In some cases, the task parallelism methods employed to date are able to restore much of the potential wall‐clock speedup. The specific application highlighted here focuses on the connection between microstructure and material performance using a polycrystal plasticity‐based multi‐scale method. However, the parallel load balancing issues are germane to a broad class of multi‐scale problems. Copyright © 2011 John Wiley & Sons, Ltd.     

Haustration of the ascending aorta as differential diagnosis of aortic dissection

Clostridium perfringens isolated from sheep and goat with enterotoxaemia at necropsy and from healthy animals at slaughter were typed using specific PCR assays for the detection of the alpha-, beta- and epsilon-toxin genes. Clostridium perfringens isolated from all 52 animals with pathological signs of enterotoxaemia showed the presence of the alpha- and epsilon-toxin genes but were devoid of the beta-toxin gene. These strains could therefore be identified as type D, characteristic for clostridial enterotoxaemia of sheep, lambs and goats. In contrast, Cl. perfringens isolated from 11 of 13 healthy animals only contained the alpha-toxin gene which is typical for type A. Two of the healthy animals contained Cl. perfringens with the alpha- and epsilon-toxin genes. However, when several individual Cl. perfringens colonies were analysed from each of these two animals, only a small percentage was found to contain the epsilon-toxin gene, whereas the majority of the colonies were of type A with the alpha-toxin gene only. This is in contrast to the findings from the diseased animals which contained practically only type D Cl. perfringens. The beta-toxin gene was not found in any Cl. perfringens isolate from goat and sheep. Comparison of the PCR data with results obtained by the classical biological toxin assay using the mouse model showed a good correlation.