Traveling Salesman Problem with Clustering

In the original traveling salesman problem, the traveling salesman has the task to find the shortest closed tour through a proposed set of nodes, touching each node exactly once and returning to the initial node at the end. For the sake of the tour length to be minimized, nodes close to each other might not be visited one after the other but separated in the tour. However, for some practical applications, it is useful to group nodes to clusters, such that all nodes of a cluster are visited contiguously. Here we present an approach which leads to an automatic clustering with a clustering parameter governing the sizes of the clusters.     

How Many Molecules are Required to Obtain a Steady Faradaic Current from Mediated Electron Transfer at a Single Nanoparticle on a Supporting Surface?

We investigate the chronoamperometric noise characteristics of electron‐transfer reactions occurring on single nanoparticles (NPs) and assemblies of well‐separated NPs on a supporting surface. To this end, we combine a formerly described expression for the steady‐state current of a single particle with the shot‐noise model and derive an expression for the signal‐to‐noise ratio as a function of bulk concentration and particle radius. Our findings are supported by random‐walk simulations, which closely match the analytical results.     

Real‐Time NMR Spectroscopy for Studying Metabolism

Current metabolomics approaches utilize cellular metabolite extracts, are destructive, and require high cell numbers. We introduce here an approach that enables the monitoring of cellular metabolism at lower cell numbers by observing the consumption/production of different metabolites over several kinetic data points of up to 48 hours. Our approach does not influence cellular viability, as we optimized the cellular matrix in comparison to other materials used in a variety of in‐cell NMR spectroscopy experiments. We are able to monitor real‐time metabolism of primary patient cells, which are extremely sensitive to external stress. Measurements are set up in an interleaved manner with short acquisition times (approximately 7 minutes per sample), which allows the monitoring of up to 15 patient samples simultaneously. Further, we implemented our approach for performing tracer‐based assays. Our approach will be important not only in the metabolomics fields, but also in individualized diagnostics.     

Study of sintering processes in copper and nickel by positron annihilation

In the advanced stage of non-isothermal sintering, vacancy clusters are present as prevailing type of defects. Their concentration considerably decreases at further temperature increase, and it can be concluded that thermally activated conversion of multiple vacancies into climbable dislocations takes place. Hence, in conformity with recent experiments, coincidence of intensive material transport ($ \dot \varepsilon $ e-maximum) and decrease of defect concentration (recovery) can be understood.     

Ultrasonic measurement technique to study thermometric effects in glass

Ultrasonic measurements of shear wave propagation in alkali containing glasses reveal temporal instabilities and thermal after-effects which parallel thermometric effects, the secular rise and zero point depression in the ice point of glass thermometers. The ultrasonic method of observing these effects has advantages over the thermometric technique. Sound velocity is a dynamic quantity proportional to the elastic moduli and density which can be measured on an absolute basis and over a frequency range if desired. Thus in measuring instabilities in the elastic properties of glass the ultrasonic method provides additional information over the use of the thermometric technique whose measured changes relate only to density changes in the glass and only on a relative basis. In addition sound velocity can be measured over as wide a temperature range as desired extending from cryogenic to above glass transition range temperatures. Also no fixed reference points are required as with thermometers. Sample preparation is relatively simple and the availability of ‘packaged’ ultrasonic measurement facilities makes this method of measuring very small changes (ppm) in elastic properties very attractive.Data as a function of time and temperature are presented for a series of alkali-lead-silicates incorporating separately Li, Na, K, Rb, Cs, and for a lead silicate containing the alkaline earth Ba. The results indicate the reversible nature of the instabilities and after-effects and express their magnitudes and sensitivities to the temperature and temperature interval of measurement. They are also related to the thermal history of the glass, and the concentration and species of the incorporated alkali.     

On the validity of constraints on light elementary particles and extra-dimensional physics from the Casimir effect

We discuss the constraints on the parameters of a Yukawa interaction obtained from the indirect measurements of the Casimir pressure between parallel plates using the sphere–plate configuration. Recently, it was claimed in the literature that the application of the proximity force approximation (PFA) to the calculation of a Yukawa interaction in the sphere–plate configuration could lead to a large error of order 100% in the constraints obtained. Here we re-calculate the constraints both exactly and using the PFA, and arrive at identical results. We elucidate the reasons why an incorrect conclusion was obtained suggesting that the PFA is inapplicable to calculate the Yukawa force.     

Asynchronous sampling for ultrafast experiments with low momentum compaction at the ANKA ring

A high‐repetition‐rate pump–probe experiment is presented, based on the asynchronous sampling approach. The low‐α mode at the synchrotron ANKA can be used for a time resolution down to the picosecond limit for the time‐domain sampling of the coherent THz emission as well as for hard X‐ray pump–probe experiments, which probe structural dynamics in the condensed phase. It is shown that a synchronization of better than 1 ps is achieved, and examples of phonon dynamics of semiconductors are presented.     

Functional Analysis of Tube Chain Conveyors

This paper describes some of the aspects necessary for the design and use of tube chain conveyors. It is based on the reports of experienced experts and recent tube chain conveyor experimental results. The aim of the research work is the formulation of general technical regulations for tube chain conveyors. Theoretical models were developed, which allow the calculation of the motion resistances in all parts of the conveyor by the use of empirical extracted correction factors. Specially designed measurement equipment enabled the measurement of the important chain tractive force from the closed tube system. The measurements show the influence of the major operational parameters and the bulk solid properties.