Inferring kinetic dissolution of NaCl in aqueous glycol solution using a low-cost apparatus and population balance model

An experimental methodology for inferring brine dissolution rate in monoethylene glycol (MEG) solutions at different temperatures using a webcam combined with a mathematical model is presented. The measurement system is designed to track the RGB (red, green, and blue) colour variations during the dissolution process. A dynamic model augmented with the population balance equation is applied to describe the dissolution process. Moreover, the dissolution rate is consistently related to the temperature and MEG concentration through the driving force based on the Gibbs energy and chemical affinity. The applied low-cost measurement apparatus proved to be a useful resource for tracking the dissolution dynamics in a wide range of undersaturation.     

An application of chemometric techniques to analyze the effects of the wave function modifications on the intermolecular stretching frequencies of the hydrogen-bonded complexes

Factorial design and principal component models are used to determine how ab initio H-bond stretching frequencies depend on characteristics of the molecular orbital wave functions of acetylene–HX, ethylene–HX and cyclopropane–HX π-type hydrogen complexes with X=F, Cl, CN, NC and CCH. The results obtained for the three sets of complexes show that factorial design and principal component analyses complement each other. Factorial design calculations clearly show that these frequencies are affected mostly by inclusion of electron correlation on the calculation level. On average, their values are increased by about 25 cm⁻¹ due to a change from the Hartree–Fock (HF) to Möller–Plesset 2 (MP2) level. Valence, diffuse and polarization main effects as well as valence–diffuse, diffuse–correlation and polarization–correlation interaction effects are also important to better describe a factorial model to the H-bond stretching frequencies of these hydrogen complexes. This simplified model has been successful in reproducing the complete ab initio results, which correspond to two hundred and forty calculations. Principal component analyses applied only to hydrogen-bonded complexes whose experimental frequencies are known, has revealed that the six-dimensional original space can be accurately represented by a bidimensional space defined by two principal components. Its graphical representation reveals that the experimental intermolecular stretching frequencies are in closest agreement with the MP2/6–31+G and MP2/6–311+G ab initio results.     

Reasons for personnel turnover in a private health facility

In this article 1 describe efforts to build a genetically informative, population-based sample of black twins to study physical frailty and aging in the United States. This project involves the use of governmental registries combined with sampling techniques developed to overcome limitations in the registry data. Two analytical approaches to measures of disability are included to illustrate the types of questions that can be addressed with this sample. These results suggest that physical disability in late life has both genetic and environmental determinants. Only with a genetically informative sample can evidence be collected indicating that frailty may be driven by fixed processes (i.e., disability resulting from activation of senescence genes), fluid processes (i.e., disability resulting from changes in the features of the environment), or a combination of both.     

Carbon fibre cloth as an electrode material: electrical conductivity and mass transfer

The paper deals with carbon fibre cloth electrodes, employed in the fabrication of composite materials. The electrical conductivity of single bundles, groups of bundles and cloth is studied. Ohm's law applies to the electrical conduction in the direction of the fibre length, but bundle conductivity decreases with the number of fibres in the bundle. Electrochemical mass transfer between a flowing electrolyte and a cloth arranged as a flow-through or a flow-by porous electrode indicates the existence of double porosity in the material. Due to double porosity, only the external surface of the cloth works as an electrode. This finding shows that the material is not suitable for such an application.     

自动实时X射线检测技术在半导体制程控制中的应用

对X光检测的不同技术在半导体制程上的应用作了详细的介绍;着重讨论了全旋倾斜(off-axis)X射线技术的特点和优势。     

Energy storage devices for future hybrid electric vehicles

Powertrain hybridization as well as electrical energy management are imposing new requirements on electrical storage systems in vehicles. This paper characterizes the associated vehicle attributes and, in particular, the various levels of hybrids. New requirements for the electrical storage system are derived, including: shallow-cycle life, high dynamic charge acceptance particularly for regenerative braking and robust service life in sustained partial-state-of-charge usage. Lead/acid, either with liquid or absorptive glass-fibre mat electrolyte, is expected to remain the predominant battery technology for 14 V systems, including micro-hybrids, and with a cost-effective battery monitoring system for demanding applications. Advanced AGM batteries may be considered for mild or even medium hybrids once they have proven robustness under real-world conditions, particularly with respect to cycle life at partial-states-of-charge and dynamic charge acceptance. For the foreseeable future, NiMH and Li-ion are the dominating current and potential battery technologies for higher-functionality HEVs. Li-ion, currently at development and demonstration stages, offers attractive opportunities for improvements in performance and cost. Supercapacitors may be considered for pulse power applications. Aside from cell technologies, attention to the issue of system integration of the battery into the powertrain and vehicle is growing. Opportunities and challenges for potential “battery pack” system suppliers are discussed.     

Characterization of Oleogels Based on Waxes and Their Hydrolyzates

In this paper, the structuring of liquid oils, also known as oleogelation, is systematically investigated for the first time using a quasi-quaternary mixing system approach. Native waxes with different quantities of wax esters (WE), n-alkanes (hydrocarbons (HC)), fatty acids (FA), and fatty alcohols (FaOH) are applied in mixtures with hydrolyzed waxes to systematically change the composition. Hydrolyzed waxes contain high levels of FA and FaOH. The model systems are investigated on microscopic level (brightfield light microscopy (BFM), cryogenic scanning electron microscopy (cryo-SEM)) as well as on their macroscopic properties (rheology, gel hardness) and calorimetric behavior (differential scanning calorimetry (DSC)). It is found that sunflower wax (SFW)-based gels (12% structurant) become less hard on any admixture. Beeswax (BW)-based gels show significant increases in hardness when 25% and 50% (w/w) hydrolyzate are admixed. This could be related to stepwise crystallization. Further analysis reveals that the dissolution/melting behavior of the wax ester mixtures can be surprisingly well described as ideal solubility of a single pseudocomponent. The approach to unravel the individual contributions of the different species present in waxes is successful and marks a first step to better understand the systematic of wax functionality as oleogelators. Practical Application: The substitution of hardstock fats in structured oil phases is of interest for two reasons. The improved nutritional profile oleogels offer are beneficial for public health while the elimination of palm oil based ingredients appears to be a general public desire. Among the technical solutions for non-TAG oil structuring waxes are very promising. This is primarily due to their availability, prior consumption, potentially low cost for functionality. Currently waxes are technically and scientifically wrongly treated as single components. In order to better utilize the potential of waxes and design future sourcing strategies it is necessary to understand the wax functionality at a compositional/molecular level. This contribution marks the first step into this direction by considering classes of molecules with respect to their contribution to functionality. This understanding is considered as a key for future compositional design.     

Effect of Step Size in Incremental Loading Tests

Using the crack-growth model, the deviation of real fracture stress from the stressing level measured by stepwise incremental loading with three starting modes is calculated. For both static and dynamic fatigue, the relative error depends only on the relative increment size and the crack-growth parameter, n. The usefulness of stepwise incremental loading for strength testing can be confirmed.     

Gripper Design for Radio Base Station Autonomous Maintenance System

For an autonomous system to perform maintenance tasks in a networking device or a radio base station (RBS), it has to deal with a series of technological challenges ranging from identifying hardware-related problems to manipulating connectors. This paper describes the development of a robot maintenance system dedicated to detect and resolve faulty links caused by unplugged or poorly connected cables. Although the maintenance system relies on four subsystems, we significantly focus on our low-cost and efficient custom gripper solution developed to handle RJ45 Ethernet connectors. To examine our gripper, we conducted three experiments. First, a qualitative questionnaire was submitted to 30 users in the case of the teleoperated scenario of the gripper attached to a robotic arm. Similarly, we also tested the automatic operation mode. The results showed that our system is reliable and delivers a highly efficient maintenance tool in both teleoperated and autonomous operation modes. The practical experiment containing the removal or unplugging of connectors demonstrated our gripper’s ability to adequately handle these, whereas the feedback from the questionnaire pointed to a positive user experience. The automatic test assessed the gripper’s robustness against the continuous operation.