Perceptual depth compression for stereo applications

Conventional depth video compression uses video codecs designed for color images. Given the performance of current encoding standards, this solution seems efficient. However, such an approach suffers from many issues stemming from discrepancies between depth and light perception. To exploit the inherent limitations of human depth perception, we propose a novel depth compression method that employs a disparity perception model. In contrast to previous methods, we account for disparity masking, and model a distinct relation between depth perception and contrast in luminance. Our solution is a natural extension to the H.264 codec and can easily be integrated into existing decoders. It significantly improves both the compression efficiency without sacrificing visual quality of depth of rendered content, and the output of depth‐reconstruction algorithms or depth cameras.     

Plant optimisation by retrofitting using a hierarchical method: Entrainer selection,recycling and heat integration

Systematic procedures for reducing wastes in complex chemical plants are needed to allow efficient optimisation. Here, a hierarchical procedure was applied to the optimisation of a real industrial plant to reduce wastes as well as energy and raw material consumption. In the case studied, the continuous production of methyl-butynol (MBI), acetylene reacts with acetone. The solvent ammonia and acetylene are recycled to the reactor. Unreacted substrates and by-products are separated from the product stream by distillation. Part of the unreacted acetone can be reused for other purposes after distillation. A substantial part of the unreacted substrates and by-products is delivered to a wastewater treatment plant. These waste streams constitute a substantial problem for the operation of this plant. First, waste streams were characterised and tracked back to their origin. Following the hierarchical design procedure, the overall input–output structure was fixed. The entrainer in the present process was critically examined and options were suggested. Then various recycle schemes were considered for later detailed study. The existing plant was simulated using ASPENPLUS. After adjusting the model to all important aspects of the real process scheme, excellent agreement between actual process performance data and simulation was obtained. The various process schemes were simulated and assessed for their economic and ecological performance. The objective functions used included utility, substrate and catalyst costs, as well as costs for wastewater treatment. Additionally, the environmental burden related to energy supply was accounted for by a carbon dioxide tax as suggested by the Nordic countries. The process changes included separation of unreacted acetone from the product stream and recycling to the reactor. By-products were converted back to substrates in an additional reactor separation system and recycled. In various simulated process configurations and operational schemes substantial economic and ecologic improvements were achieved. This study demonstrates the usefulness of hierarchical approaches combined with process simulation for plant optimisation. ©1997 SCI     

Combined photoelectrochemical conditioning and surface analysis of InP photocathodes: II. Photoelectron spectroscopy

The photoelectrochemical modification of p-InP(111) surfaces in HCl and H₂SO₄ is investigated. In 0.5 M HCl a photoreduction/oxidation procedure via cyclic voltammetry leads to a solar energy conversion efficiency of the p-InP/vanadium^2+,3+—4 M HCl/C photoelectrochemical solar cell (PECS) of η=11.6% in natural sunlight. The optimisation procedures are followed by surface analysis methods performed ex-situ at the modified InP electrodes after cathodic and after anodic polarisation in the supporting acidic electrolytes and in the redox solution. X-ray photoelectron spectroscopy (XPS), ultraviolet photoelectron spectroscopy (UPS) and low energy electron diffraction (LEED) are used. At cathodic polarisation in H₂SO₄, XPS shows formation of indium metal and In_x(SO₄)_y compounds, whereas in HCl a stable interfacial film consisting of indium monochloride to a smaller extent of indium oxides is formed. This film is optimised by cycling in HCl having a thickness of 10±3 Å. Cyclic polarisation in the vanadium redox electrolyte changes the composition and thickness. Whereas in HCl, the optimised interphase consists of 0.7 parts InCl and 0.3 parts In(PO₃)₃, phosphates are absent after optimisation in V^2+/3+ and more indium oxide is found. The film thickness is reduced to 6±2 Å for the InCl component and about 0.6 monolayers of indium oxide are found. UPS measurements are mainly used to derive an energy band diagram of the semiconductor/film/electrolyte junction. The results show in that the stabilisation of the film in chloride containing electrolytes can be explained by the relative conduction band positions of p-InP with respect to cathodic decomposition energies. Since the electron affinity increases with surface phase formation in HCl, whereas it stays low in sulphuric acid, the ongoing corrosion in the latter solution can be understood, the LEED data show that the surface phase is ordered with lattice constants close to InP, indicating the formation of a hitherto unknown InOCl phase. According to the results we propose reaction mechanisms for dissolution and stabilisation and present schematic energy band diagrams which explain the corrosion processes in H₂SO₄ and the passivation phenomenon in HCl. The influence of the properties of the interfacial film on the functioning of the solar cell is outlined.     

Synthesis of S‐Adenosyl‐L‐homocysteine Capture Compounds for Selective Photoinduced Isolation of Methyltransferases

Understanding the interplay of different cellular proteins and their substrates is of major interest in the postgenomic era. For this purpose, selective isolation and identification of proteins from complex biological samples is necessary and targeted isolation of enzyme families is a challenging task. Over the last years, methods like activity‐based protein profiling (ABPP) and capture compound mass spectrometry (CCMS) have been developed to reduce the complexity of the proteome by means of protein function in contrast to standard approaches, which utilize differences in physical properties for protein separation. To isolate and identify the subproteome consisting of S‐adenosyl‐L ‐methionine (SAM or AdoMet)‐dependent methyltransferases (methylome), we developed and synthesized trifunctional capture compounds containing the chemically stable cofactor product S‐adenosyl‐L ‐homocysteine (SAH or AdoHcy) as selectivity function. SAH analogues with amino linkers at the N6 or C8 positions were synthesized and attached to scaffolds containing different photocrosslinking groups for covalent protein modification and biotin for affinity isolation. The utility of these SAH capture compounds for selective photoinduced protein isolation is demonstrated for various methyltransferases (MTases) acting on DNA, RNA and proteins as well as with Escherichia coli cell lysate. In addition, they can be used to determine dissociation constants for MTase–cofactor complexes.     

An integral equation model for the magnetic flux leakage method

This paper describes a new method for the calculation of the MFL field from a given defect shape and induced magnetisation. The field is described by means of three-dimensional integral equations, providing a view similar to a standard MFL corrosion detection tool. This method allows the quick calculation of the MFL field on a standard PC.     

Characterization of wood-filled thermoplastic polyurethanes for the injection molding process

Fiber fillings of wood plastic composites (WPC) are almost exclusively limited to standard plastics such as polyethylene and polypropylene. At the Kunststofftechnik Paderborn of the University of Paderborn the wood fiber filling of engineering plastics is being promoted. WPC with different fiber types and fiber contents based on two thermoplastic polyurethanes (TPU) were compounded and subsequently characterized. We found that the physicochemical properties of the materials differ from standard plastic-based WPC. Wood filling with increasing fiber content did not immediately correlate with an increase in density. A decrease in density and swelling of the compound was detected with reaching a critical fiber content. Our compounds showed an increased water absorption at high-fiber contents over time, which can be described logarithmically. The observed viscosity curves obey the Ostwald and de Waele power law, but an increased viscosity at increased fiber content was not apparent for both TPU matrices.     

DNA mismatch-specific base flipping by a bisacridine macrocycle

Most, if not all, enzymes that chemically modify nucleobases in DNA flip their target base from the inside of the double helix into an extrahelical position. This energetically unfavorable conformation is partly stabilized by specific binding of the apparent abasic site being formed. Thus, DNA base-flipping enzymes, like DNA methyltransferases and DNA glycosylases, generally bind very strongly to DNA containing abasic sites or abasic-site analogues. The macrocyclic bisacridine BisA has previously been shown to bind abasic sites. Herein we demonstrate that it is able to specifically recognize DNA base mismatches and most likely induces base flipping. Specific binding of BisA to DNA mismatches was studied by thermal denaturation experiments by using short duplex oligodeoxynucleotides containing central TT, TC, or TG mismatches or a TA match. In the presence of the macrocycle a strong increase in the melting temperature of up to 7.1 degrees C was observed for the mismatch-containing duplexes, whereas the melting temperature of the fully matched duplex was unaffected. Furthermore, BisA binding induced an enhanced reactivity of the mispaired thymine residue in the DNA toward potassium permanganate oxidation. A comparable reactivity has previously been observed for a TT target base mismatch in the presence of DNA methyltransferase M.TaqI. This similarity to a known base-flipping enzyme suggests that insertion of BisA into the DNA helix displaces the mispaired thymine residue into an extrahelical position, where it should be more prone to chemical oxidation. Thus, DNA base flipping does not appear to be limited to DNA-modifying enzymes but it is likely to also be induced by a small synthetic molecule binding to a thermodynamically weakened site in DNA.     

Development of an integrated process for electrochemical reaction and chromatographic SMB-separation

A new continuous process combining electrochemical reaction and chromatographic simulated-moving-bed (SMB) separation is presented. To demonstrate the potential of process integration, this reactor concept is applied to the direct electrochemical production of arabinose by means of simulation. Experimentally verified models of reactor and column units are combined with a model of the electrochemical SMB-reactor. These process units are characterized individually and their model parameters are discussed. The electrochemical reaction inside the microreactor can be described by a series reaction, which has an impact on the design of the integrated process: as the reaction should take place in areas of the SMB-process with maximum educt concentration, the reactors are switched on and off during operation. The integrated process shows interaction between the reaction and the separation to diminish side reactions. Case studies prove the theoretical feasibility of the integrated process. Compared to a conventional process with a reactor followed by a SMB-separation, higher yields can be obtained.