Visual and acoustic cues may serve as aposematic signals that warn predators of poisonous foods. Olfactory aposematism, the use of innocuous odors as warning signals for toxic foods, is another possible means of alerting an animal that a potential food item is unpalatable. Although it has been suggested that olfactory aposematism might be the principle mode of warning utilized by plants in their defense against herbivores, experimental evidence is lacking. This study demonstrates that the opossum,Didelphis virginiana, can utilize an innocuous volatile compound found naturally in a mushroom as a warning signal for a delayed illness caused by mushroom toxin. This supports the contention that characteristic odors of toxic plants may serve a warning function, protecting herbivores from being poisoned and plants from being consumed. 相似文献
A novel perforated bipole trickle-bed electrochemical reactor is investigated for the electro-synthesis of alkaline peroxide.
The process uses a relatively simple cell configuration in which a single electrolyte flows with oxygen gas in a flow-by graphite
felt cathode, sandwiched between a micro-porous diaphragm and a perforated bipolar electrode plate. The graphite felt cathodes
are 120 mm high by 25 mm wide and have a thickness of 3.2 mm. The reactor is operated at current densities in the range 1–5 kA m−2, ca. 800 kPa (abs) pressure and temperature (In/Out) 20–45 °C with one and two-cells. The reactor shows good performance
(current efficiency ∼78% at 2 kA m−2 and a specific energy of 5 kWh per kg of peroxide generated) with peroxide concentrations from 0.02 to 0.15 M in 1 M NaOH. 相似文献
Building Information Models (BIM) are comprehensive digital representations of buildings, which provide a large set of information originating from the different disciplines involved in the design, construction and operation processes. Moreover, accessing the data needed for a specific downstream application scenario is a challenging task in large-scale BIM projects. Several researchers recently proposed using formal query languages for specifying the desired information in a concise, well-defined manner. One of the main limitations of the languages introduced so far, however, is the inadequate treatment of geometric information. This is a significant drawback, as buildings are inherently spatial objects and qualitative spatial relationships accordingly play an important role in the analysis and verification of building models. In addition, the filters needed in specific data exchange scenarios for selecting the information required can be built by spatial objects and their relations. The lack of spatial functionality in BIM query languages is filled by the Query Language for Building Information Models (QL4BIM) which provides metric, directional and topological operators for defining filter expressions with qualitative spatial semantics. This paper focuses on the topological operators provided by the language. In particular, it presents a new implementation method based on the boundary representation of the operands which outperforms the previously presented octree-based approaches. The paper discusses the developed algorithms in detail and presents extensive performance tests. 相似文献
We present a performance-based facial animation system capable of running on mobile devices at real-time frame rates. A key component of our system is a novel regression algorithm that accurately infers the facial motion parameters from 2D video frames of an ordinary web camera. Compared with the state-of-the-art facial shape regression algorithm [1], which takes a two-step procedure to track facial animations (i.e., first regressing the 3D positions of facial landmarks, and then computing the head poses and expression coefficients), we directly regress the head poses and expression coefficients. This one-step approach greatly reduces the dimension of the regression target and significantly improves the tracking performance while preserving the tracking accuracy. We further propose to collect the training images of the user under different lighting environments, and make use of the data to learn a user-specific regressor, which can robustly handle lighting changes that frequently occur when using mobile devices. 相似文献
Phase extraction, phase unwrapping and phase to height conversion are consecutive steps within the fringe projection method for reconstruction of 3D objects. The procedure of determining discontinuities on the wrapped phase, resolving them and achieving the unwrapped phase is called phase unwrapping. A software system was developed that provides the ability to create many kinds of patterns with a verity of desirable properties suitable for different demands in fringe projection systems. In our previous work, an experimental study was reported based on a multi-wavelength unwrapping approach. In the following work, we implemented a new method called binary code pattern unwrapping that is based on time analysis. A comparison of the two unwrapping approaches in terms of resolution, quality, noise, depth accuracy, and computational cost is provided. 相似文献
The role of ozone was studied for two different configurations combining non-thermal plasma (NTP) and heterogeneous catalysis, namely the use of a gas phase plasma with subsequent exposure of the effluent to a catalyst in a packed-bed reactor (post-plasma treatment) and the placement of the catalyst directly in the discharge zone (in-plasma catalysis). Non-porous and porous alumina and silica were deployed as model catalysts. The oxidation of immobilised hydrocarbons, toluene as a volatile organic compound and CO as an inorganic pollutant were studied in both operational modes.
While conversion and selectivity of hydrocarbon oxidation in the case of catalytic post-plasma treatment can be fully explained by the catalytic decomposition of O3 on γ-Al2O3, the conversion processes for in-plasma catalysis are more complex and significant oxidation was also measured for the other three materials (-Al2O3, quartz and silica gel). It became obvious that additional synergetic effects can be utilised in the case of in-plasma catalysis due to short-lived species formed in the NTP.
The capability of porous alumina for ozone decomposition was found to be correlated with its activity for oxidation of carbon-containing agents. It could be clearly shown that the reaction product CO2 poisons the catalytic sites at the γ-Al2O3 surface. The catalytic activity for O3 decomposition can be partially re-established by NTP treatment. However, for practical purposes the additional reaction pathways provided by in-plasma catalytic processes are essential for satisfactory conversion and selectivity. 相似文献