Interface dipoles of organic molecules on Ag(111) in hybrid density-functional theory

We investigate the molecular acceptors 3,4,9,10-perylene-tetracarboxylic acid dianhydride (PTCDA), 2,3,5,6-tetra uoro-7,7,8,8-tetracyanoquinodimethane (F4TCNQ), and 4,5,9,10-pyrenetetraone (PYTON) on Ag(111) using densityfunctional theory. For two groups of the HSE(\alpha, \omega) family of exchange-correlation functionals (\omega = 0 and \omega = 0.2\AA) we study the isolated components as well as the combined systems as a function of the amount of exact-exchange (\alpha). We find that hybrid functionals favour electron transfer to the adsorbate. Comparing to experimental work-function data, we report for (\alpha) ca. 0.25 a notable but small improvement over (semi)local functionals for the interface dipole. Although Kohn-Sham eigenvalues are only approximate representations of ionization energies, incidentally, at this value also the density of states agrees well with the photoelectron spectra. However, increasing (\alpha) to values for which the energy of the lowest unoccupied molecular orbital matches the experimental electron affinity in the gas phase worsens both the interface dipole and the density of states. Our results imply that semi-local DFT calculations may often be adequate for conjugated organic molecules on metal surfaces and that the much more computationally demanding hybrid functionals yield only small improvements.Comment: submitted to New Journal of Physics (2013). More information can be found at http://th.fhi-berlin.mpg.de/site/index.php?n=Publications.Publication

Image based control system for improving fiber injection molding process

Fiber injection molding is an innovative process for the resource-efficient production of near net-shape long fiber preforms. The filling of the mold is crucial for the repeatability and uniformity of the produced preforms. For improving the fiber injection process a control system based on image processing has been developed. With a camera the current mold filling is recorded and processed by artificial neural networks. This information on the filling state is used for an adaptive control of the injection nozzle. The control system is validated experimentally with results showing improved reproducibility of the fiber injection molding process

Method for the Investigation of Mold Filling in the Fiber Injection Molding Process Based on Image Processing

Fiber Injection Molding is an innovative process for manufacturing 3D fiber formed parts. Within the process fibers are injected in a special mold through a movable nozzle by an air stream. This process allows a resource efficient production of near net-shape long fiber-preforms without cutting excess. For the properties of the preforms the mold filling is decisive, but current state of the art lacks methods to monitor mold filling online. In this paper a system for monitoring the mold filling based on image processing methods is presented. Therefor a camera and back-lighting has been integrated into a fiber injection mold. The detected filling level and fiber distribution is passed to the PLC of the fiber injection molding machine, which allows the operator to monitor the current mold filling state by means of a visual display. The image processing approach consists of preprocessing, binarization and segmentation. For the preprocessing and binarization several methods including a k-means algorithm, the Otsu thresholding method and a convolutional artificial neural network have been implemented and evaluated. Additionally the illumination of the mold has been investigated and found to have a very large influence on the quality of the results of all investigated methods. The results of the binarization are evaluated on the basis of ground truth images, where an absolute difference between labeled and binarized images is formed and the number of misinterpreted pixels is counted. Among the investigated methods, the method based on the Otsu threshold has been found to be the most efficient with regard to the achievable performance as well as to the correct detection of the current filling. The investigated approach allows the acquisition of more data about the mold filling process to improve models

Analysis of Basis Weight Uniformity Indexes for the Evaluation of Fiber Injection Molded Nonwoven Preforms

Fiber injection molding is an innovative approach for the manufacturing of nonwoven preforms but products currently lack a homogeneous fiber distribution. Based on a mold-integrated monitoring system, the uniformity of the manufactured preforms will be investigated. As no universally accepted definition or method for measuring uniformity is accepted yet, this article aims to find a suitable uniformity index for evaluating fiber injection molded nonwovens. Based on a literature review, different methods are implemented and used to analyze simulated images with given distribution properties, as well as images of real nonwovens. This study showed that quadrant-based methods are suitable for evaluating the basis weight uniformity. It has been found that the indexes are influenced by the number of quadrants. Changes in sample size do not affect the indexes when keeping the quadrant number constant. The quadrants-based calculation of the coefficient of variation showed the best suitability as it shows good robustness and steady index for varying degrees of fiber distribution

Integrated Gripping-system for Heating and Preforming of Thermoplastic Unidirectional Tape Laminates

Forming and overmolding of thermoplastic multi-layer UD-tape laminates has become increasingly important due to its potential for large-scale production. In the process the tape laminates have to be heated above melting temperature of the polymer in an infrared heater and then transported into the mold. To guarantee the formability of the laminate the temperature has to be maintained above the melting temperature during handling. To improve part quality a preforming of the tape laminate prior to overmolding is preferable. Integration of the preforming step in the handling process allows the shortening of the process route. In this work a gripping-system which allows further heating and preforming of the laminate during the handling process is presented. The temperature losses during transport have been modelled using the Stefan-Boltzmann law. By means of temperature measurements it is shown, that the integrated infrared-heaters allow a compensation of the cooling during handling, resulting in lower maximum heating temperature in the upstream infrared heating field and therefore a reduction of heating time and degradation of the polymer. The repeatability of the handling-integrated preforming has been evaluated using three-dimensional overlays of the resulting 3D-shaped laminates acquired by a laser scanning arm

Noxious Weed Monitoring at the Rock Creek Confluence Site

Disturbances such as fire, flooding, and compaction are important in determining and maintaining the diversity and composition of plant assemblages in ecosystems. While they can have a stabilizing effect, they can also open niches that can be exploited by noxious fast growing weeds. Controlling the abundance and spread of noxious weeds is a top priority for land managers, but can be challenging with limited resources. Therefore it is essential to establish a baseline to determine levels of weed encroachment. We have partnered with Five Valleys Land Trust (FVLT) to establish this baseline at their Rock Creek Confluence Property by using point line intercept and dry weight density methods. On site volunteer days will be organized after to do targeted hand pulling and planting. This approach should create a closer connection between the larger community and the Rock Creek Confluence property, while creating a system to evaluate the effectiveness of volunteer efforts

Microstructural Effects During Chemical Mechanical Planarization of Copper

Novel die-stacking schema using through-wafer interconnects require vias to be filled with electroplated Cu, resulting in thick copper films, and requiring an aggressive first-step CMP. This work investigates the effects of microstructure on CMP of copper films, which are not presently well understood. Bulk and local removal rates were investigated for several different microstructures. Surface orientation maps were created and the orientations of individual grains were correlated with topographical data to elucidate local removal behavior. Cu removal depends on the details of the microstructure, and certain microstructures allowed for either faster or more uniform removal of thick Cu films

ARAM: an automated image analysis software to determine rosetting parameters and parasitaemia in Plasmodium samples

Additional file 3: Figure S3. Bland-Altman diagrams. Left Comparison of the cell detection by ARAM and an operator. Right Comparison of the determined rosette size by ARAM and an operator