A fast, three-layer neural network for path finding

A path-planning algorithm is proposed to find a path based on local rules applied to a three-layer artificial neural network. Each layer consists of two-dimensionally arranged neurons with recurrent connections within a limited neighbourhood. The output of one layer determines the weights of the connections in the next layer. In principle, the method is based on a diffusion process, but is modified such that it does not suffer from several drawbacks involved in this algorithm. By application of a nonlinear transformation in layer 2, the diffusion front has the qualitative properties of a propagation wave. Therefore, limited resolution of the units is not critical, in contrast to classical diffusion algorithms. Furthermore, the algorithm generally does not suffer from the superposition of diffusion gradients when several paths are possible. The diffusion takes place in a space covered with 'obstacle potentials' which decrease the velocity of the diffusion front. In this way the path can maintain an adjustable safety margin in relation to the obstacles, for example, to cope with problems of incomplete knowledge of the obstacle's position. The algorithm thus combines the advantages of the diffusion algorithm, namely avoidance of local minima, of wave propagation, i.e. coping with limited resolution, and the potential field approach, i.e. maintaining a safety margin in relation to obstacles. The distributed architecture also allows for 'spatial interpolation' between the units (coarse coding), thereby providing smooth path forms. A comparison with paths developed by human subjects shows some similarity on the qualitative level, but there are also obvious differences.     

FORMI: Integrating Adaptive Fragmented Objects into Java RMI

Distributed object-oriented applications are commonly implemented atop middleware platforms such as CORBA, .NET Remoting, and Java remote method invocation (RMI). These platforms provide a simple mechanism to invoke methods of remote objects. Increasingly more applications are demanding nonfunctional properties such as fault tolerance, high availability, and adaptivity, which require extensions to distributed objects' basic interaction model. A fragmented-object model, such as the one Marc Shapiro proposed, can provide the required flexibility. It's far more generic and flexible than the traditional client-server approach. A fragmented object is a truly distributed object; it consists of multiple fragments located on multiple nodes. Such a model allows arbitrary partitioning of state and functionality on these fragments, and arbitrary internal interaction between fragments of a single object. We have investigated integrating a fragmented-object model into CORBA (AspectIX), which requires internal modifications to the CORBA object request broker. Our approach for transparently integrating fault-tolerant objects into .NET Remoting is also useful for seamlessly integrating fragmented objects. Our FORMI architecture integrates fragmented objects into Java RMI without requiring internal modifications to the RMI runtime     

五富兰克林大楼

该大楼有20层,包含55个公寓,在楼中可以眺望啥德逊河、东河和曼哈顿的天际线。 该大楼有一个戏剧性、极富装饰性的立面,灵感来自Tribeca的19世纪的铸铁建筑和当代时尚。闪闪发光的黑色金属横带将包装的墙面扭曲,划分了阳台、平台和遮阳篷的位置,同时体现了立面的框架感。     

Oxygen feed membranes in autothermal steam-reformers - A robust temperature control

In conventional autothermal steam-reformers, the spatial temperature distribution leads to hot-spot problems. Here we demonstrate a solution approach for this problem using ceramic membranes with highly interconnected open pores and a permeability that varies over the length of the reformer. Due to this spatially non-constant characteristic, these membranes function as oxygen feed distributors. Predictions based on a theoretical optimization showed that almost isothermal characteristics should be possible in small-scale applications. For experimental validation, membranes were produced via the HAPES processing route, which leads to open porosities between 71 and 78% and permeability constants varying from 3.8 × 10⁻¹² to 3.9 × 10⁻¹³ m². The experimental results show that a membrane with staged permeabilities can reduce a typical temperature peak for 94% down to a value below 5 K deviation from the isothermal behavior without any losses in conversion rate or hydrogen and CO-selectivities. Additionally, it could be confirmed that a premix of 6.5% oxygen to the feed gases is necessary to obtain optimal results.     

Charge transport through graphene junctions with wetting metal leads

Graphene is believed to be an excellent candidate material for next-generation electronic devices. However, one needs to take into account the nontrivial effect of metal contacts in order to precisely control the charge injection and extraction processes. We have performed transport calculations for graphene junctions with wetting metal leads (metal leads that bind covalently to graphene) using nonequilibrium Green's functions and density functional theory. Quantitative information is provided on the increased resistance with respect to ideal contacts and on the statistics of current fluctuations. We find that charge transport through the studied two-terminal graphene junction with Ti contacts is pseudo-diffusive up to surprisingly high energies.     

Statistical results and implications of the enchytraeid reproduction ringtest

An international ringtest of the enchytraeid reproduction test (ERT) was performed by 29 laboratories, with two substances (carbendazim and 4-nitrophenol) and two test designs (NOEC and ECx). Although many participants had no previous experience in enchytraeid ecotoxicology, the majority of tests were performed accurately and fulfilled the validity criteria, demonstrating method feasibility. However, variability in control reproduction was fairly high and exceeded the proposed validity criterion of a 50% coefficient of variation in 24% of the tests. Variability may be lowered with increasing experience and by using better defined animals, either through synchronized culture or by weighing animals before the test. In all tests, NOECs were higher than the EC10 values, sometimes by more than 1 order of magnitude and usually closer to the EC50. This shows that NOECs, due to their dependence on test design and variability, are an unsatisfactory measure of "no toxicity" for regulatory purposes. Preferably, differences to the control at NOEC concentrations should always be given. To achieve appropriate power and to avoid frequent false negatives, in the ERT, high numbers of replicates would be necessary. We favor using regression approaches with means of replicates whenever possible.     

电容信号的数字化校正

本文介绍了如何应用由德国Analog Microelectronics GmbH公司开发的框架集成电路CAV414和一个简单的低价位的RISC微处理器组成一个可以对电容信号进行数字化修正的处理系统。     

Mechanisms of Fatigue in Cemented Carbides at Elevated Temperatures

Cemented carbides are mainly used as cutting tools in various fields of application. In nearly all industrial uses they have to resist wear and concurrent complex thermomechanical loading, often including alternating mechanical loads at high temperatures. It has been shown that cemented carbides suffer lifetime‐limiting fatigue under cyclic loads at 25 °C caused by subcritical crack growth. Present investigations show that strong, temperature‐dependent fatigue effects occur in cemented carbides at elevated temperatures. TEM investigations revealed temperature‐dependent processes that are responsible for the changes in the fatigue behavior: at low temperatures a phase transformation of the Co‐binder phase and at higher temperatures oxidation in the cracks and brittle–ductile transitions of cubic carbides.     

The X-ray structure of (MeBm2t)1-cyclosporin complexed with cyclophilin A provides an explanation for its anomalously high immunosuppressive activity

For most of the cyclosporin A (CsA) analogs, there is generallya good correlation between cyclophilin binding and immunosuppression.However, this relationship does not seem to hold for 4-[(E)-2-butenyl]-4,4,N-trimethyl-L-threonine¹(MeBm₂t)¹-CsA.Its affinity for cyclophilin was reported to be {small tilde}1percent; that of CsA and its immunosuppressive activity invitro was shown to be {small tilde} 30% that of CsA. We reporthere the crystal structure of a complex between recombinanthuman cyclophilin A (CypA) and (MeBm₂t)¹-CsA which has beendetermined by X-ray crystallography at 2.2 Å resolutionand refined to an Rfactor of 16.3%. (MeBm₂t)¹-CsA shows a similarbound conformation and network of interactions to CypA as CsA.The measured lower affinity for CypA cannot therefore be explainedby a different mode of binding. We propose that the poor affinityto CypA could be accounted for by the existence of an equilibriumin aqueous solution between a ‘cyclophilin bound conformation’and a ‘nonbinding conformation’ of (MeBm₂t)¹-CsA.The relatively high immunosuppressive activity is suggestedto result from slight conformational differences observed inthe effector domain     

SOME SIMPLE TESTS OF THE MOVING-AVERAGE UNIT ROOT HYPOTHESIS

Abstract. This paper deals with three test statistics for a moving-average (MA) unit root. The spectral test is based on the estimate of the spectral density at frequency zero. The variance difference statistic compares the sample variance of the integrated series with the estimated variance imposing the MA unit root constraint. Furthermore, Tanaka's score type test statistic is modified to improve the power in higher order models. The asymptotic power of the tests is considered and Monte Carlo experiments are performed to investigate the small sample properties of the tests. Finally, the tests are applied to a number of economic time series to determine the degree of integration.