Weighted minimal hypersurface reconstruction

Many problems in computer vision can be formulated as a minimization problem for an energy functional. If this functional is given as an integral of a scalar-valued weight function over an unknown hypersurface, then the sought-after minimal surface can be determined as a solution of the functional's Euler-Lagrange equation. This paper deals with a general class of weight functions that may depend on surface point coordinates as well as surface orientation. We derive the Euler-Lagrange equation in arbitrary dimensional space without the need for any surface parameterization, generalizing existing proofs. Our work opens up the possibility of solving problems involving minimal hypersurfaces in a dimension higher than three, which were previously impossible to solve in practice. We also introduce two applications of our new framework: We show how to reconstruct temporally coherent geometry from multiple video streams, and we use the same framework for the volumetric reconstruction of refractive and transparent natural phenomena, bodies of flowing water.     

Influence of NO2 on the selective catalytic reduction of NO with ammonia over Fe-ZSM5

The influence of NO₂ on the selective catalytic reduction (SCR) of NO with ammonia was studied over Fe-ZSM5 coated on cordierite monolith. NO₂ in the feed drastically enhanced the NO_x removal efficiency (DeNOx) up to 600 °C, whereas the promoting effect was most pronounced at the low temperature end. The maximum activity was found for NO₂/NO_x = 50%, which is explained by the stoichiometry of the actual SCR reaction over Fe-ZSM5, requiring a NH₃:NO:NO₂ ratio of 2:1:1. In this context, it is a special feature of Fe-ZSM5 to keep this activity level almost up to NO₂/NO_x = 100%. The addition of NO₂ to the feed gas was always accompanied by the production of N₂O at lower and intermediate temperatures. The absence of N₂O at the high temperature end is explained by the N₂O decomposition and N₂O-SCR reaction. Water and oxygen influence the SCR reaction indirectly. Oxygen enhances the oxidation of NO to NO₂ and water suppresses the oxidation of NO to NO₂, which is an essential preceding step of the actual SCR reaction for NO₂/NO_x < 50%. DRIFT spectra of the catalyst under different pre-treatment and operating conditions suggest a common intermediate, from which the main product N₂ is formed with NO and the side-product N₂O by reaction with gas phase NO₂.     

Surface properties of surfactants derived from natural products. Part 2: Structure/property relationships—Foaming,dispersion, and wetting

Several novel and some previously known, mostly sugar-based, surfactants have been synthesized, and their surface properties have been characterized and compared with commercial nonylphenol ethoxylates. The dispersion properties of the surfactants were studied by mixing carbon black into an aqueous surfactant solution. It was found that open sugars, as the headgroup, give rise to higher conformational repulsion and hence more effective dispersion properties than ringclosed sugar headgroups (e.g., furanoside or pyranoside forms). No conclusions could be made about the differences in dispersion properties between surfactants with aliphatic or aromatic tail groups. Increasing the area of the tail group, however, by using twin-chain tail groups increased the dispersion properties of the surfactants further. The surfactants’ ability for wetting a hydrophobic parafilm surface was studied. The sugar-based surfactants were found generally to possess poor wetting properties.     

Nonoxynol‐9‐α‐cyclodextrin inclusion compound and its application for the controlled release of nonoxynol‐9 spermicide

Nonoxynol‐9 (N‐9) is the most active ingredient in commercially available spermicidal products in the United States. There are many applications of cyclodextrin inclusion complexes (CD‐ICs), but there are no reported studies investigating the formation of and controlled release from a N‐9 spermicide‐CD‐IC. We have successfully formed the inclusion compound between N‐9 and α‐CD using a solution‐heating technique. The N‐9‐α‐CD‐IC was characterized by Fourier Transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, differential scanning calorimetry, thermogravimetric analysis, and wide angle X‐ray diffraction observations. Silicone elastomer (SILASTIC MDX4‐4210) film embedded with crystalline N‐9‐α‐CD‐IC was prepared and evaluated for its efficacy in the controlled release of N‐9 spermicide against bovine sperm. Silicone elastomer with N‐9‐α‐CD‐IC was as successful in reducing the motility and viability of bovine spermtazoa as silicone elastomer swollen with an equivalent amount of neat N‐9. The permeability of the flexible silicone elastomer apparently enables the N‐9 spermicide to diffuse from its embedded inclusion complex crystals to contact, immobilize, and kill bovine sperm cells. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Bioconjugation of (CdSe)ZnS Quantum Dots Using a Genetically Engineered Multiple Polyhistidine Tagged Cohesin/Dockerin Protein Polymer

Summary: We have constructed bioconjugates consisting of genetically modified cohesin/dockerin protein polymers combined with (CdSe)ZnS colloidal quantum dots. This recombinant protein contains fusions of Clostridium thermocellum cellulosomal cohesin and dockerin domains and a C‐terminal 6×‐histidine tag. These unique cohesin/dockerin monomeric building blocks (ca. 60 kDa) were allowed to self‐assemble, yielding oligomers and polymers, which were subsequently characterized by high‐pressure size exclusion chromatography (HPSEC). The C‐terminal 6×‐His tags from each monomer facilitate binding to the quantum dot surface chemistry while mix the protein polymers with water‐soluble QDs at neutral pH. Using HPSEC, we were able to fractionate the reaction mixture into two major distributions of bioconjugate species. Scanning transmission electron microscopy (STEM) and photoluminescence spectroscopy (PL) were employed to characterize the components from these chromatographic fractions. The fraction containing the larger bioconjugates contained clusters of quantum dots surrounded by protein polymers with an estimated radius of 190 ± 30 Å and an apparent molecular weight of 8 000 ± 3 000 kDa. The STEM images from the fraction containing the smaller species were amenable to detailed analysis and graphical simulation that revealed species containing one, two, or three quantum dots surrounded by 10, 15, or 18 protein monomers, respectively. Our data demonstrate strong binding coefficients not only between the protein monomers to form polymers, but also with the (CdSe)ZnS colloidal quantum dots and thus provides a method of producing stable, water‐soluble luminescent quantum dot bioconjugates. PL spectroscopic analysis shows that the samples from both chromatographic fractions have strong excitonic emission with a peak at ca. 2.2 eV (562 nm).

STEM images of cohesin/dockerin protein polymer‐QD conjugates from the HPSEC elution peak. A represents a typical STEM image 512 × 512 nm scanning field showing the conjugates containing 1, 2, and 3 QDs with 10, 15, and 18 protein monomers surrounded, respectively.     

PaderMAC: Energy-efficient machine to machine communication for cyber-physical systems

Wireless sensor nodes typically switch between sleep and wake periods. This poses a rendezvous problem on message senders and recipients. X-MAC, a state of the art sensor network medium access control (MAC) protocol, solves this problem by sending a strobe of short preambles from the message sender until the message recipient wakes up. Upon wake-up, the recipient receives the next strobe, signals the message sender that it is ready to receive, and the message transmission can take place. In sink oriented communication, geographic greedy routing, and link reversal routing, a forwarding node may have more than one potential next hop forwarding node. X-MAC does not support such opportunistic communication patterns. Instead it requires the sender to name the recipient explicitly. However, preamble length can be saved when message transmission starts as soon as the first one of the set of potential next hop nodes is waken up by a preamble. This requires PaderMAC, a new MAC protocol, where the decision on the next hop node is shifted from the sender to the receiver. This work specifies the PaderMAC protocol, explains the implementation of that protocol using TinyOS and the MAC layer architecture (MLA), describes a contribution to the MLA which is useful also for other MAC layer implementations, and presents the results of a testbed and theoretical performance study. The testbed study compares PaderMAC in conjunction with opportunistic routing to X-MAC in conjunction with path-based routing and shows how PaderMAC reduces the preamble length, better balances the load and further improves the end-to-end latency within the network.     

Oscillation overlaid shearing of sheet

One of the most frequently used sheet metal processing methods is shearing. While using the shearing method a cut edge is usually created which often clearly fails to meet the desired quality. The optimum cut edge quality is as rectangular and as burr-free as possible. Trials made at the IFUM showed, that the quality of cut edges can be improved by overlaying the movement of the punch with an oscillation. Through different test rows the mechanism and impact of oscillation on the shearing process are investigated. This paper reports about tensile and friction tests made on sheet metal with oscillation overlay, high speed cutting tests and test series with a new designed tool which allows stamping sheet metal also with an oscillation overlay. The test series show, that oscillation can have an effect on the tensile strength, friction and work hardening of sheet metal and as a result on the cutting force and the cut edge quality.     

Modulare Verfahrenstechnik: Apparateentwicklung für wandlungsfähige Produktionssysteme

The process industry faces the challenges of intensified, global competition with increasing market dynamics. Modular, transformable production concepts promise a better adaption to these in the dimensions of throughput, product mix and production location. In order to unfold the full potential, modularization and transformability have to be applied not only on plant and logistics level but also on apparatus level. Characteristics like setup and scaling concepts are discussed. Examples for modular apparatuses concerning the process engineering tasks of mixing, heat exchange, reaction and separation are presented and further research needs are derived.     

Oxime crosslinked polymer networks: Is every reversible covalent bond suitable to create self‐healing polymers?

The incorporation of reversible covalent bonds into polymeric materials offers the possibility to generate polymers with self‐healing ability. For this purpose, three new oxime crosslinkers are synthesized and crosslinked by the copolymerization with different commercially available methacrylates via a photo‐polymerization process. These crosslinked materials are investigated regarding a potential self‐healing behavior. Moreover, the influence of different additives (polymerizable acids, photo acids, and acid developers) to enable self‐healing is studied in detail. Thereby, the limit of self‐healing based on reversible covalent bonds is reached in these materials. Due to the high stability of the oxime bonds in bulk materials no exchange reactions as well as no self‐healing behavior could be observed. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44168.     

Determination of the composition of biodiesel-diesel blends using the dielectric constant

There are many methods used to measure the composition of biodiesel in diesel. However, standard methods are limited by high cost and limited precision. Here is proposed a low-cost sensor to determine biodiesel in binary blends of biodiesel/diesel, using the dielectric constant. The concentrations were varied from 0–9% at frequencies from 100–2000 Hz. The correlation curves between the dielectric constant and the biodiesel/diesel concentration included an adjustment factor of 0.992. Moreover, the values of the dielectric constant obtained for each blend were statistically distinct, yielding precise measurements.