Inverse form finding with h-adaptivity and an application to a notch stamping process

The aim is to determine the optimized semi-finished workpiece geometry to its given target geometry after a forming process. Hereby, a novel approach for inverse form finding, a type of a shape optimization, is applied to a notch stamping process. As a special feature, h-adaptive mesh refinement is considered within the iteratively performed forming simulation

Posttraumatic Growth Following Cancer: The Role of Cognitive Processing, Anxiety, Depression and Perceived Threat

This study explored several predictors of posttraumatic growth (PTG) in a sample of 169 breast, prostate and colorectal cancer survivors. The first aim was to determine the influence of Anxiety, Depression and Perceived Threat (defined as the combination of Life Outlook Threat, i.e., the degree a cancer diagnosis challenged a survivor\u27s assumptive world, and Physical Threat, i.e., threat to mortality and physical well-being) in the prediction of Positive and Negative Cognitive Processing. The second aim was to examine the effect of Anxiety, Depression, Perceived Threat, and Positive and Negative Cognitive Processing in the predication of PTG. Cancer survivors who were treated at one of the Denver Division clinics of the Rocky Mountain Cancer Center participated in the study. Since little empirical research has been conducted utilizing the variable of cognitive processing in the psychological literature, the study sought to investigate how Anxiety, Depression, and Perceived Threat were related to Positive and Negative Cognitive Processing. Hierarchical regression analyses were used to explore four primary hypotheses. The results of the study revealed several important findings. Physical Threat, Depression, and Permanent After-Effects of Cancer Treatment significantly predicted Positive Cognitive Processing, with lower levels of Physical Threat and Depression and no After-Effects of Treatment predicting higher Positive Cognitive Processing. Life Outlook Threat, Positive Cognitive Processing, and Type of Cancer Treatment Received also significantly predicted PTG. The findings indicated that greater life outlook threat and positive cognitive processing as well as receiving more than one form of cancer treatment predicted greater growth. None of the variables reached significance in predicting Negative Cognitive Processing and Negative Cognitive Processing failed to significantly predict PTG. While perceived threat and cognitive processing have a strong theoretical basis in the emergence of growth, the constructs have received little empirical attention. This is the first study that has assessed how being diagnosed with cancer challenges, rather than alters, a survivor\u27s assumptive world. The results of the study provide evidence that increases in life outlook threat and positive cognitive processing are related to PTG

A 19-channel d.c. SQUID magnetometer system for brain research

A 19-channel d.c. SQUID magnetometer system for neuromagnetic investigations is under constuction. The first-order gradiometers for sensing the signal are placed in a hexagonal configuration. D.c. SQUIDs based on niobium/aluminium technology have been developed, leading to a field sensitivity of about 5 fT/ Hz. SQUID read-out is realized with a resonant transformer circuit at 100 kHz. The multichannel control and detection electronics are compactly built

Notes on Antiphon ΛΟΓΟΣ ΠEPI METAΣTAΣEΩΣ

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Induction methods used in low temperature physics

A study has been made of induction bridges used in low temperature physics.\ud \ud In Part 1 the design of a mutual inductance bridge of the Hartshorn type is discussed. This design is based on a critical analysis of impurity effects of the different parts of the Hartshorn bridge. With this equipment frequencies up to 0.5 MHz can be used. Two methods have been developed to examine the secondary signal. In one of these use has been made of AD conversion techniques. In the other one, the secondary signal, produced by a superconducting sample, which is generally distorted, is analysed by using a Fourier expansion.\ud \ud In Part 2 equipment is described which enables us to measure the phase and amplitude of the harmonics of the output signal of the bridge. For synchronous detection a reference signal of the same frequency of the harmonic of interest is required. This reference signal is generated from the input signal of the bridge by means of a digital frequency multiplier with programmable multiplication factor N.\ud \ud In Part 3 some experimental results, showing the possibilities of the equipment, on some superconductors are presented

Trapezoidal ac magnetic fields:a powerful technique for the investigation of type 11 superconductors

In ac losses in type II superconductors three contributing factors may be distinguished. These are connected with the three parameters in the Critical State Model: the critical current density Jc, surface screening currents denoted by Ben(Ba) and Bex (Ba), and the flux conductivity σff. In this paper the authors present an inductive technique which makes it possible to determine these three parameters separately. For this purpose, ac magnetic fields of trapzoidal waveform are applied. The theoretical background of the technique will be discussed together with the experimental equipment designed for these experiments. The technique has been verified by means of numerical model calculations. Finally, some experimental results are given to illustrate the possibilities of the technique

Representative elementary volumes for evaluating effective seismic properties of heterogeneous poroelastic media

Understanding and quantifying seismic energy dissipation in fluid-saturated porous rocks is of considerable interest because it offers the perspective of extracting information with regard to the elastic and hydraulic rock properties. An important, if not dominant, attenuation mechanism prevailing in the seismic frequency band is wave-induced fluid pressure diffusion in response to the contrasts in elastic stiffness in the mesoscopic-scale range. An effective way to estimate seismic velocity dispersion and attenuation related to this phenomenon is through the application of numerical upscaling procedures to synthetic rock samples of interest. However, the estimated seismic properties are meaningful only if the underlying sample volume is at least of the size of a representative elementary volume (REV). In the given context, the definition of an REV and the corresponding implications for the estimation of the effective seismic properties remain largely unexplored. To alleviate this problem, we have studied the characteristics of REVs for a set of idealized rock samples sharing high levels of velocity dispersion and attenuation. For periodically heterogeneous poroelastic media, the REV size was driven by boundary condition effects. Our results determined that boundary condition effects were absent for layered media and negligible in the presence of patchy saturation. Conversely, strong boundary condition effects arose in the presence of a periodic distribution of finite-length fractures, thus leading to large REV sizes. The results thus point to the importance of carefully determining the REV sizes of heterogeneous porous rocks for computing effective seismic properties, especially in the presence of strong dry frame stiffness contrasts. </jats:p

Feasibility of time-lapse seismic methodology for monitoring the injection of small quantities of CO2 into a saline formation, CO2CRC Otway Project

A key objective of Stage 2 of the CO2CRC Otway Project is to explore the ability of geophysical methods to detect and monitor injection of greenhouse gas into a saline formation. For this purpose, injection of some 10,000 30,000 tonnes of CO2-rich mixture into the Paaratte formation, a saline aquifer located at a depth of about 1,400 m, is planned. Before such an injection experiment is undertaken, we assess the feasibility of geophysical monitoring using computer modelling. To examine the detectability of the plume we need to estimate the time-lapse signal and time- lapse noise. The time lapse signal is modelled using flow simulations, fluid substitution and seismic forward modelling. In order to assess the applicability of time-lapse seismic to monitor the injection, the predicted signal is compared to the time-lapse noise level from the recent 4D seismic survey acquired at the Otway site in 2009-2010. The methodology is applied to two alternative reservoir intervals located at a depth of 1392-1399 m and 1445-1465 m below the sea level, respectively. These intervals are considered to be the two possible options for the injection. The results show that injection into the lower interval will produce a plume of a larger thickness and smaller lateral extent, and a seismic response that is more likely to be detectable. The developed feasibility assessment workflow, and the results of its application to the Otway site, can be used to assess the ability of seismic methods to detect and monitor greenhouse gas leakage in other CCS projects

Time-lapse sonic logs reveal patchy CO2 saturation in-situ

Based on time-lapse sonic and neutron porosity logs from the Nagaoka CO2 sequestration experiment, a P-wave velocity-saturation relation at reservoir depth is retrieved. It does not coincide with either of the end-member models of uniform and patchy saturation but falls in between even if realistic error estimates for the host rock properties are considered. Assuming a random distribution of CO2 patches it is shown that the mechanism of wave-induced flow can be evoked to explain this velocity-saturation relation. Characteristic CO2 patch size estimates range from 1 to 5 mm. Such mesoscopic heterogeneity can be responsible for attenuation and dispersion in the well logging frequency band