Evolution of weakly non-linear shallow water waves generated by a moving boundary

Summary In this study we describe the evolution of weakly non-linear shallow water waves in a rectangular channel of 16 m length which aregenerated by a moving boundary. We present a detailed comparison of computaticnal and observational waveheight-time series and thus verify the theoretical model as presented by Villeneuve and Savage [27].Three different types of wave generating devices were used: pistons with vertical and inclined frontal faces, submerged boxes and a rotating plate. Waveheight-time series are recorded at eight different positions along the channel by electrical resistivity gauges, and velocity profiles are determined at certain selective cross sections. Data of many wave experiments are presented in nondimensional form. This representation reveals that the initial wave forms depend upon a Froude number of the motion of the wave generator, the slope angle of the wedge-type pistons and on the dimensionless displaced volume. Evolving waveheight-time series that are recorded at the various gauges are compared with those obtained from computations by use of equations which generalize the Boussinesq equations to include time variations of the boundaries.The method of inverse scattering is applied both, experimental and numerical waveheight-time series are prescribed as initial data. Results are tested relative to two different observers one fixed in time the other fixed in space. Deviations are shown to be small in all cases.     

Benign breast changes and the risk for subsequent breast cancer: an update of the 1985 consensus statement. Cancer Committee of the College of American Pathologists

The Cancer Committee of the College of American Pathologists has prepared an update of the consensus statement on premalignant breast lesions and breast cancer risk that was originally published in the Archives of Pathology & Laboratory Medicine in 1986. The objective of this publication is to better define the relative breast cancer risk associated with specific histologic abnormalities by incorporating data derived from recent case-control studies. Explanatory notes are used to document and explain specific risk classifications. In addition to refining the degree of risk associated with individual lesions, such as fibroadenoma and atypical hyperplasia, this update includes a discussion of age-specific breast cancer risk and provides examples that can be used when counseling patients.     

Silphinene Sesquiterpenes as Model Insect Antifeedants

Silphinene sesquiterpenes are established chrysomelid antifeedants. In this work, nine silphinene analogs, 11-acetoxy-5-angeloyloxysilphinen-3-one (1), 11-acetoxy-5-tigloyloxysilphinen-3-one (2), 11-acetoxy-5-iso- butyryloxysilphinen-3-one (3), 11-hydroxy-5-angeloyloxysilphinen-3-one (4), 11,5-dihydroxysilphinen-3-one (5), 11,5-diacetoxysilphinen-3-one (6), 5,11-diisobutyryloxysilphinen-3-one (7), silphinen-3,5,11-trione (8), and O-methyl-5-epicantabrenolic acid methyl ester (10), and a presilphiperfolane sesquiterpene (9) were tested against several divergent insect species, including the lepidopteran Spodoptera littoralis, the chrysomelid Leptinotarsa decemlineata, and five aphid species, and their antifeedant effects were compared with those of picrotoxinin, a GABA-antagonist, and thymol, an allosteric modulator for insect GABA receptors. All insects tested responded to at least one silphinene analog and/or GABA antagonist. Compound 3 and thymol were effective antifeedants against all species tested except S. littoralis, with varying potencies according to their feeding ecologies. The toxicity of these compounds was species-dependent and did not correlate with their antifeedant effect.     

Sensitivity analysis based preform die shape design using the finite element method

This paper uses a finite element-based sensitivity analysis method to design the preform die shape for metal forming processes. The sensitivity analysis was developed using the rigid visco-plastic finite element method. The preform die shapes are represented by cubic B-spline curves. The control points or coefficients of the B-spline are used as the design variables. The optimization problem is to minimize the difference between the realized and the desired final forging shapes. The sensitivity analysis includes the sensitivities of the objective function, nodal coordinates, and nodal velocities with respect to the design variables. The remeshing procedure and the interpolation/transfer of the history/dependent parameters are considered. An adjustment of the volume loss resulting from the finite element analysis is used to make the workpiece volume consistent in each optimization iteration and improve the optimization convergence. In addition, a technique for dealing with fold-over defects during the forming simulation is employed in order to continue the optimization procedures of the preform die shape design. The method developed in this paper is used to design the preform die shape for both plane strain and axisymmetric deformations with shaped cavities. The analysis shows that satisfactory final forging shapes are obtained using the optimized preform die shapes.     

Note: The intermodulation lockin analyzer

Nonlinear systems can be probed by driving them with two or more pure tones while measuring the intermodulation products of the drive tones in the response. We describe a digital lockin analyzer which is designed explicitly for this purpose. The analyzer is implemented on a field-programmable gate array, providing speed in analysis, real-time feedback, and stability in operation. The use of the analyzer is demonstrated for intermodulation atomic force microscopy. A generalization of the intermodulation spectral technique to arbitrary drive waveforms is discussed.     

The dynamics of avalanches of granular materials from initiation to runout. Part II. Experiments

Summary This paper describes a model to predict the flow of an initially stationary mass of cohesionsless granular material down a rough curved bed and checks it against laboratory experiments that were conducted with two different kinds of granular materials that are released from rest and travel in a chute consisting of a straight inclined section, a curved segment that is followed by a straight horizontal segment. This work is of interest in connection with the motion of landslides, rockfalls and ice and dense flow snow avalanches. Experiments were performed with two different granular materials, nearly spherical glass beads of 3 mm nominal diameter, Vestolen particles (a light plastic material) of lense type shape and 4 mm nominal diameter and 2,5 mm height. Piles of finite masses of these granular materials with various initial shapes and weight were released from rest in a 100 mm wide chute with the mentioned bent profile. The basal surface consisted of smooth PVC, but was in other experiments also coated with drawing paper and with sandpaper. The granular masses under motion were photographed and partly video filmed and thus the geometry of the avalanche was recorded as a function of position and time. For the two granular materials and for the three bed linings the angle of repose and the bed friction angle were determined. The experimental technique with which the laboratory avalanches were run are described in detail as is the reliability of the generated data. We present and use the depth-averaged field equations of balance of mass and linear momentum as presented by Savage and Hutter [28]. These are partial differential equations for the depth averaged streamwise velocity and the distribution of the avalanche depth and involve two phenomenological parameters, the internal angle of friction, ø, and a bed friction angle, , both as constitutive properties of Coulomb-type behaviour. We present the model but do not derive its equations. The numerical integration scheme for these equations is a Lagrangian finite difference scheme used earlier by Savage and Hutter [27],[28]. We present this scheme for completeness but do not discuss its peculiarities. Comparison of the theoretical results with experiments is commenced by discussing the implementation of the initial conditions. Observations indicate that with the onset of the motion a dilatation is involved that should be accomodated for in the definition of the initial conditions. Early studies of the temporal evolution of the trailing and leading edges of the granular avalanche indicate that their computed counterparts react sensitively to variations in the bed friction angle but not to those of the internal angle of friction. Furthermore, a weak velocity dependence of the bed friction angle, , is also scen to have a small, but negligible influence on these variables. We finally compare the experimental results with computational findings for many combinations of the masses of the granular materials and bed linings. It is found that the experimental results and the theoretical predictions agree satisfactorily. They thus validate the simple model equations that were proposed in Savage and Hutter [28].     

Virtual worlds as knowledge management platform – a practice‐perspective

Virtual worlds, as electronic environments where individuals can interact in a realistic manner in form of avatars, are increasingly used by gamers, consumers and employees. Therefore, they provide opportunities for reinventing business processes. Especially, effective knowledge management (KM) requires the use of appropriate information and communication technology (ICT) as well as social interaction. Emerging virtual worlds enable new ways to support knowledge and knowing processes because these virtual environments consider social aspects that are necessary for knowledge creating and knowledge sharing processes. Thus, collaboration in virtual worlds resembles real‐life activities. In this paper, we shed light on the use of Second Life (SL) as a KM platform in a real‐life setting. To explore the potential and current usage of virtual worlds for knowledge and knowing activities, we conducted a qualitative study at IBM. We interviewed IBM employees belonging to a special workgroup called ‘Web 2.0/virtual worlds’ in order to gain experience in generating and exchanging knowledge by virtually collaborating and interacting. Our results show that virtual worlds – if they are able to overcome problems like platform stability, user interface or security issues – bear the potential to serve as a KM platform. They facilitate global and simultaneous interaction, create a common context for collaboration, combine different tools for communication and enhance knowledge and knowing processes.     

Consumers' Creative Talent: Which Characteristics Qualify Consumers for Open Innovation Projects? An Exploration of Asymmetrical Effects

Virtual customer integration and open innovation are considered as appropriate means to improve the success of new product development. However, only when consumers are qualified and motivated to contribute promising ideas and relevant know‐how they are able to add value to a producer's innovation process. In this study, we explore the symmetric and asymmetric impact of various creativity components on consumers' idea generation, concept development, or prototype building abilities as well as interest in co‐creation projects. Our results show that creativity components are of different importance. While some characteristics are needed above certain thresholds to successfully accomplish a certain development task, exceeding those does not necessarily lead to better outputs. Other characteristics improve the creative output only if they exceed specific levels.     

Crowdsourcing as a service – from pilot projects to sustainable innovation routines

While crowdsourcing may strengthen a company's innovation performance, it is only rarely embedded in organizations as an innovation practice. Our action research shows that organizations often struggle with crowdsourcing projects as they represent a different form of innovation projects and require additional capabilities and skills e.g., to frame a crowd challenge, deal with IP rights, manage the crowd, or integrate the vast input into innovation projects. To overcome these problems, organizations have to invest in project-led learning to establish easy-to-use templates and routines e.g., to handle offered incentives or the applied winner selection processes. They further need to enable business-led learning as the established innovation structures, processes, and management practices do not cope with crowdsourcing projects and present some rigidities causing high coordination efforts. Organizations that are willing to run a number of consecutive crowdsourcing projects may rapidly improve their capabilities and even come up with scalable crowdsourcing services. Our findings further suggest that crowdsourcing, digital platforms, artificial intelligence, and as-a-service approaches may also add to general project capability building.