Learning cellular automata rules for binary classification problem

This paper proposes a cellular automata-based solution of a binary classification problem. The proposed method is based on a two-dimensional, three-state cellular automaton (CA) with the von Neumann neighborhood. Since the number of possible CA rules (potential CA-based classifiers) is huge, searching efficient rules is conducted with use of a genetic algorithm (GA). Experiments show an excellent performance of discovered rules in solving the classification problem. The best found rules perform better than the heuristic CA rule designed by a human and also better than one of the most widely used statistical method: the k-nearest neighbors algorithm (k-NN). Experiments show that CAs rules can be successfully reused in the process of searching new rules.     

An evaluation of MODIS and SeaWiFS bio-optical algorithms in the Baltic Sea

An extensive bio-optical data set from field measurements was used to evaluate the performance of standard Moderate Resolution Imaging Spectroradiometer (MODIS) and Sea-viewing Wide Field-of-view Sensor (SeaWiFS) ocean color (in-water) algorithms in the Baltic Sea, which represents an example of optically complex Case 2 waters with high concentration of colored dissolved organic matter (CDOM). The data set includes coincident measurements of radiometric quantities, chlorophyll a concentration (Chl a), and absorption coefficient of CDOM, which were taken on 25 cruises between 1993 and 2001. The data cover a wide range of variability with Chl a in surface waters from about 0.3 to 100 mg m⁻³. All the MODIS pigment algorithms examined as well as the SeaWiFS OC4v4 algorithm showed a systematic and large overestimation in chlorophyll retrievals. The mean systematic and random errors based on our entire data set exceeded 150% or even 200% in some cases, making these standard algorithms inadequate for pigment determinations in the Baltic. Although new parameterization of the standard pigment algorithms based on our field measurements in the Baltic resulted in a significant reduction of errors, the overall performance of such regionally tuned algorithms remained unsatisfactory. For example, the mean normalized bias (MNB) for the regionally tuned MODIS chlor_a_2 algorithm was reduced to 26% (from over 200% for the standard algorithm), but the root mean square (RMS) error was still large (>100%). The MODIS K_490 algorithm for estimating the diffuse attenuation coefficient of downwelling irradiance showed the best performance among all the algorithms examined. With the new coefficients based on our field data, the regional version of this algorithm showed an acceptable level of errors, MNB=4% and RMS=30%. In addition to the apparent problems of the standard in-water bio-optical algorithms, we found that the atmospheric correction currently in use for MODIS and SeaWiFS imagery usually fails to retrieve upwelling radiances emerging from the Baltic Sea. The match-up comparisons of the coincident in situ and satellite determinations of normalized water-leaving radiances showed generally poor agreement, especially in the blue spectral region. It appears that new approaches for ocean color algorithms are required in the Baltic Sea.     

Nonuniform Heating in Zinc Oxide Varistors Studied by Infrared Imaging and Computer Simulation

State-of-the-art infrared (IR) thermal imaging was used to monitor the heating of ZnO varistors by electrical transients. On a macroscopic scale (e.g., 10 mm), heating in large varistor blocks (i.e., diameter of 42 mm) was found to be the greatest near the block edges and to be approximately radially symmetric in blocks fabricated at a low aspect ratio. In blocks fabricated at a higher aspect ratio, the heating was less symmetric, presumably because uniform properties are more difficult to achieve. Nonuniform heating in large blocks can be attributed to processing-induced variations in the electrical properties of the blocks. On an intermediate size scale (e.g., 1 mm), the heating in small varistor disks (e.g., diameter of 10 mm) was observed to be most intense along localized electrical paths. The high electrical conductivity of these paths originates from the statistical fluctuations in properties that inevitably occur in polycrystalline materials. On a microscopic scale (e.g., 10 μm), the heating in thin varistor slices (e.g., thickness of 100 μm) was observed to be localized in strings of tiny hot spots. The hot spots occur at the grain boundaries in a conducting path, where the potential is decreased across Schottky-type barriers and the heat is generated. The experimentally observed heating is interpreted by applying transport theory and using computer simulations. It is shown that, on the scale of the grain size, the heat transfer is too fast to permit temperature differences that could cause a varistor failure. Current localization and nonuniform heating on an intermediate size scale can have a microstructural origin (e.g., statistical fluctuations of grain sizes and grain-boundary properties). However, these are shown to be significant only in small varistors, whereas destructive failures (puncture and cracking) of large varistor blocks can be caused only by nonuniform heating on a macroscopic scale.     

A study of an up- and a down-pumping wide-blade hydrofoil impeller: Part II. CFD analysis

Two different ways of using CFD to determine the flow field produced by the complex, wide-blade hydrofoil APV-B2 impeller are presented. The use of the “sliding mesh” approach was not successful and the reasons are discussed. Details of the numerical solution of the momentum transfer equations are described for the case of an axially-symmetrical jet model. The flow field for the single impeller pumping either upwards or downwards at 200 rpm was simulated using the structured Fluent code. Good agreement of CFD predictions with LDA velocity data was found, though the maximum local energy dissipation rate was 2 1/2 to 5 times lower than was estimated from the experiments. The power numbers predicted by CFD were slightly higher than those obtained experimentally. The flow fields for dual and triple impellers pumping upwards were also simulated and used to guide larger scale homogenisation experiments.     

Noise Evaluation for Pavement Maintenance in Metropolitan Highway Bridges

Dynamic response of a bridge under traffic load induces acoustic energy at the bridge surface. The acoustic energy change generates an additional coupled noise component caused by vibration of a bridge deck associated with the pavement conditions and moving velocity of the vehicle. This paper presents a three-dimensional finite-element method developed for the dynamic response and noise propagation model, and analyzes the coupled effect induced by traffic loading based on different pavement conditions. Even though vibration-induced noise at the bridge is below the audible frequency range of 20–20,000?Hz, it amplifies the traffic noise source to the highly annoyed level of noise in the metropolitan area. Among several factors that contribute to the traffic noise, interaction between pavement and vehicle is considered according to the different surface roughness and vehicle velocity. The result shows that poor pavement condition contributes to the increase of traffic noise at a high traveling speed of the vehicle. In the pavement maintenance stage, the coupled effect as an additional noise source should be considered to mitigate the traffic noise for its added value in conjunction with regulation of engine emission noise and construction of a noise barrier.     

Identification of Critical Success Factors for Construction Innovation: From the Perspective of Strategic Cooperation

Nowadays, China is in the period of industrialization, modernization and urbanization. The investment to the infrastructure is increasing which requires the support from construction innovation. Construction innovation is project-based cooperative innovation. The innovation based cooperation not only focuses inside the boundary of project, but also emphasizes the long-term strategic cooperation among the participants of innovation network. Therefore, it is significant to explore the Critical Success Factors (CSFs) of construction innovation based on the viewpoint of strategic cooperation. This paper first presents the definition and characteristics of construction innovation. By tracking the international frontiers, the authors studied a great number of literatures on the influence elements of construction innovation. Combining the effort of literature review and expert interview, this present paper identified 20 CSFs for construction innovation, which is verified and perfected by a case study in the end. The findings of this research will be of great importance for guiding the practice of construction innovation in China.     

Fault impact and fault tolerance in multiprocessor interconnection networks

Growing complexity of parallel machines coupled with increasing chip densities escalates the need for fault tolerance and recovery in these systems. In pursuit of the goal of fault-tolerant multiprocessors, many techniques have been proposed. Since methods for designing fault-tolerant processors and memories are relatively mature, the techniques considered in this paper focus on the interconnection network (ICN) linking the processors. The impact of faults on non-fault-tolerant ICNs is contrasted with that in fault-tolerant networks. Fault tolerance in ICNs is addressed at two levels, inter-node or switch level and system level. Inter-node or switch level pertains to data and control integrity and system level deals with maintaining network connectivity and adequate performance levels in the presence of faults. Fault-tolerant schemes at the switching element level warrant some form of concurrent error detection such as the use of codes usually combined with a full handshake protocol. Space–time trade-offs involved in the use of various codes and protocols are investigated. At the system level, several augmented multi-stage switching ICNs, tree and ring networks are studied. The combined provision for fault tolerance together with improved performance in the non-fault condition is emphasized. Finally, strategies for network reconfiguration and rerouting after system failure are presented.     

Atomic migration on ordering and diffusion in bulk and nanostructured FePt intermetallic

“Order-order” kinetics was studied by means of in situ and quasi-residual resistometry in bulk polycrystal stoichiometric L1₀-ordered FePt and in epitaxially deposited FePt thin film. In addition, Fe diffusion in FePt thin film was examined by means of a combination of nuclear resonant scattering and nuclear tracer techniques. In bulk FePt, a discontinuous drop of the activation energy for chemical ordering (from 2.7–15 eV) was detected below 850 K, definitely away from the Curie point (735 K). The activation energy for Fe radiotracer diffusion in the FePt thin film studied below 900 K was found to be equal to 1.7 eV (in view of the value higher than 3 eV measured above 1100 K). Kinetic Monte Carlo simulations of order-order processes in bulk and nanolayered FePt reproduced their experimentally observed multi-time-scale character. In simulated FePt nanolayers, a reorientation of the initial z-variant L1₀ superstructure into a mixture of x and y variants was definitely a dominating process.     

汽油和柴油混合燃料均质压燃(HCCI)的试验研究

汽油和柴油这两种不同特性的燃料被用作HCCI发动机的燃料。汽油具有高挥发性、易雾化和易于形成混合气的特性,被用来形成均质混合气;柴油具有良好的着火性和可燃性,被用来控制自燃和限制爆震燃烧。期望这两种特性不同而又相互补充的燃料混合后能够达到一个折衷的HCCI的燃烧性能。试验在一个专用于HCCI研究的单缸发动机上实施,采用两种中等的压缩比(10．4和15)和两种HCCI模式(进气加热和负气门叠开),试验结果证实了这种期望。结果是:随着混合燃料中柴油比例的增加,对于进气加热模式,HC- CI能稳定工作所需要的进气温度有所降低,对于负气门叠开模式,缸内平均指示压力和过量空气系数的范围有所扩展,并且两种方式下HC和NOx的排放均有所减少。