Reconfigurable handling system

The demand for more versatile assembly and handling systems to facilitate customized production is gaining in importance, especially with regard to the constantly-increasing cost pressure, to expansion of the range of product versions and the shortening of innovation cycles. As a cost-effective approach for frequently changing assembly tasks, a novel manipulation concept has been developed by combining given robot technologies. This new handling system has a modular and adaptable layout, which consists of several mobile arms to manipulate the object in six-dimensional Cartesian space. After grasping, when the arms are attached to the object, the mechanical architecture is similar to parallel manipulators or cooperating robots. As the mounting and gripping points of the arms can easily be changed, the manipulator can be reconfigured so as to match the user’s preferences and needs. In addition to the kinematic adaption the regarding task, the hardware and new functions can be reconfigured as well. Contact elements, measurement and assembly devices as well as testing modules can easily be in integrated in the concept. A modular automatic control concept combined with a self-optimizing planning tool helps the user to find the optimal configuration and realize it in an economic way.     

Structure,homogeneity ranges,magnetic, and electrical properties of the ordered Laves phases RENi4Mg with MgCu4Sn type structure

New ordered Laves phases RENi₄Mg (RE = Sc, Sm, Tb–Lu) were synthesized from the elements in sealed tantalum ampoules in an induction furnace. Six of the structures were refined on the basis of X-ray single crystal data. The diffraction experiments gave hint for small homogeneity ranges RE_1+xNi₄Mg_1?x. Magnetic susceptibility measurements show Curie–Weiss behavior for RE = Gd, Dy, Ho, Tm, Yb and the resulting effective magnetic moments suggest both stable trivalent states for all RE and a non-magnetic state for Ni. Gd_1+xNi₄Mg_1?x (x ≈ 0.12) orders antiferromagnetically at a Néel temperature of T_N = 4.6(5) K. Resistivity measurements reflect the metallic nature of these compounds.     

Deficits in emotion-regulation skills predict alcohol use during and after cognitive–behavioral therapy for alcohol dependence.

Objective: As emotion regulation is widely considered to be a primary motive in the misuse of alcohol, our aim in the study was to investigate whether deficits in adaptive emotion-regulation skills maintain alcohol dependence (AD). Method: A prospective study investigated whether emotion-regulation skills were associated with AD and whether these skills predicted alcohol use during and after treatment for AD. Participants were 116 individuals treated for AD with cognitive–behavioral therapy. Emotion regulation and severity of AD symptoms were assessed by self-report. Alcohol use during treatment was assessed by Breathalyzer and urine analysis for ethyl glucuronide; alcohol use during the 3-month follow-up interval was assessed by self-report. Results: Pretreatment emotion-regulation skills predicted alcohol use during treatment, and posttreatment emotion-regulation skills predicted alcohol use at follow-up, even when controlling for other predictors potentially related to emotion regulation. Among a broad range of specific emotion-regulation skills, the ability to tolerate negative emotions was the only skill that negatively predicted subsequent alcohol consumption when controlling for the other skills. Individuals in the AD sample reported significantly larger deficits in emotion-regulation skills than did those in a nonclinical control sample but significantly less than did those in a sample of individuals exclusively meeting criteria for major depressive disorder. Conclusions: Enhancement of general emotion-regulation skills, especially the ability to tolerate negative emotions, appears to be an important target in the treatment of AD. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Turbulent boundary layers: is the wall falling or merely wobbling?

A quick passage through five centuries of turbulence research highlights the major milestones. The more recent cornerstones include Kolmogorov??s equilibrium theory of turbulence spectrum, the universal logarithmic law of wall-bounded flows, and the proliferation of direct numerical simulations. Evidence of recent fault lines in all three major achievements is presented, but also novel remedies as well as a few contemporary accomplishments are pointed out.     

An assessment of discretizations for convection-dominated convection–diffusion equations

The performance of several numerical schemes for discretizing convection-dominated convection–diffusion equations will be investigated with respect to accuracy and efficiency. Accuracy is considered in measures which are of interest in applications. The study includes an exponentially fitted finite volume scheme, the Streamline-Upwind Petrov–Galerkin (SUPG) finite element method, a spurious oscillations at layers diminishing (SOLD) finite element method, a finite element method with continuous interior penalty (CIP) stabilization, a discontinuous Galerkin (DG) finite element method, and a total variation diminishing finite element method (FEMTVD). A detailed assessment of the schemes based on the Hemker example will be presented.     

Remote plasma etching of titanium nitride using NF3/argon and chlorine mixtures for chamber clean applications

To avoid plasma induced erosion of chamber hardware, the application of remote plasma sources to activate the etch gases was introduced. We present results on the etch behaviour of titanium nitride (TiN) using mixtures of NF₃, Cl₂ and argon. The gas mixture was excited in a remote plasma source and then routed through a reaction chamber to study the etch behaviour of TiN samples which simulate the situation at the chamber walls. The dependency of the TiN etch rate on temperature, gas flow, composition and pressure was examined. While the temperature (studied in the range 25-300 °C) turned out to be the most sensitive parameter, the general etch rate was mainly dependent on the availability of atomic fluorine. Etch products and NF₃/Cl₂ dissociation have been monitored by quadrupole mass spectrometry and infrared spectroscopy. While NF₃ showed a high decomposition up to 96%, chlorine decomposition was not observed. However the addition of chlorine increased the etch rates up to 260% in the low pressure/low temperature regime. Surface effects of chlorine addition are indicated by X-Ray Photoelectron Spectrometry and REM surface analysis.     

Chalcogenide Thermoelectrics Empowered by an Unconventional Bonding Mechanism

Thermoelectric materials have attracted significant research interest in recent decades due to their promising application potential in interconverting heat and electricity. Unfortunately, the strong coupling between the material parameters that determine thermoelectric efficiency, i.e., the Seebeck coefficient, electrical conductivity, and thermal conductivity, complicates the optimization of thermoelectric energy converters. Main‐group chalcogenides provide a rich playground to alleviate the interdependence of these parameters. Interestingly, only a subgroup of octahedrally coordinated chalcogenides possesses good thermoelectric properties. This subgroup is also characterized by other outstanding characteristics suggestive of an exceptional bonding mechanism, which has been coined metavalent bonding. This conclusion is further supported by a map that separates different bonding mechanisms. In this map, all octahedrally coordinated chalcogenides with good performance as thermoelectrics are located in a well‐defined region, implying that the map can be utilized to identify novel thermoelectrics. To unravel the correlation between chemical bonding mechanism and good thermoelectric properties, the consequences of this unusual bonding mechanism on the band structure are analyzed. It is shown that features such as band degeneracy and band anisotropy are typical for this bonding mechanism, as is the low lattice thermal conductivity. This fundamental understanding, in turn, guides the rational materials design for improved thermoelectric performance by tailoring the chemical bonding mechanism.     

The Dynamic Emission Zone in Sandwich Polymer Light‐Emitting Electrochemical Cells

In light‐emitting electrochemical cells (LECs), the position of the emission zone (EZ) is not predefined via a multilayer architecture design, but governed by a complex motion of electrical and ionic charges. As a result of the evolution of doped charge transport layers that enclose a dynamic intrinsic region until steady state is reached, the EZ is often dynamic during turn‐on. For thick sandwich polymer LECs, a continuous change of the emission color provides a direct visual indication of a moving EZ. Results from an optical and electrical analysis indicate that the intrinsic zone is narrow at early times, but starts to widen during operation, notably well before the electrical device optimum is reached. Results from numerical simulations demonstrate that the only precondition for this event to occur is that the mobilities of anions (μ_a) and cations (μ_c) are not equal, and the direction of the EZ shift dictates μ_c > μ_a. Quantitative ion profiles reveal that the displacement of ions stops when the intrinsic zone stabilizes, confirming the relation between ion movement and EZ shift. Finally, simulations indicate that the experimental current peak for constant‐voltage operation is intrinsic and the subsequent decay does not result from degradation, as commonly stated.     

Structure–Thermodynamic‐Property Relationships in Cyanovinyl‐Based Microporous Polymer Networks for the Future Design of Advanced Carbon Capture Materials

Nitrogen‐rich solid absorbents, which have been immensely tested for carbon dioxide capture, seem until this date to be without decisive molecular engineering or design rules. Here, a family of cyanovinylene‐based microporous polymers synthesized under metal‐catalyzed conditions is reported as a promising candidate for advanced carbon capture materials. These networks reveal that isosteric heats of CO₂ adsorption are directly proportional to the amount of their functional group. Motivated by this finding, polymers produced under base‐catalyzed conditions with tailored quantities of cyanovinyl content confirm the systematical tuning of their sorption enthalpies to reach 40 kJ mol^?1. This value is among the highest reported to date in carbonaceous networks undergoing physisorption. A six‐point‐plot reveals that the structure–thermodynamic‐property relationship is linearly proportional and can thus be perfectly fitted to tailor‐made values prior to experimental measurements. Dynamic simulations show a bowl‐shaped region within which CO₂ is able to sit and interact with its conjugated surrounding, while theoretical calculations confirm the increase of binding sites with the increase of Ph? C?C(CN)? Ph functionality in a network. This concept presents a distinct method for the future design of carbon dioxide capturing materials.