Approximate Boyer-Moore String Matching for Small Alphabets

Recently a new variation of approximate Boyer-Moore string matching was presented for the k-mismatch problem. The variation, called FAAST, is specifically tuned for small alphabets. We further improve this algorithm gaining speedups in both preprocessing and searching. We also present three variations of the algorithm for the k-difference problem. We show that the searching time of the algorithms is average-optimal and the preprocessing also has a lower time complexity than FAAST. Our experiments show that our algorithm for the k-mismatch problem is about 30% faster than FAAST and the new algorithms compare well against other state-of-the-art algorithms for approximate string matching.     

An augmented reality interface to contextual information

In this paper, we report on a prototype augmented reality (AR) platform for accessing abstract information in real-world pervasive computing environments. Using this platform, objects, people, and the environment serve as contextual channels to more information. The user??s interest with respect to the environment is inferred from eye movement patterns, speech, and other implicit feedback signals, and these data are used for information filtering. The results of proactive context-sensitive information retrieval are augmented onto the view of a handheld or head-mounted display or uttered as synthetic speech. The augmented information becomes part of the user??s context, and if the user shows interest in the AR content, the system detects this and provides progressively more information. In this paper, we describe the first use of the platform to develop a pilot application, Virtual Laboratory Guide, and early evaluation results of this application.     

Cold temperature PM emissions measurement: method evaluation and application to light duty vehicles

This work examines the methodology to sample and measure the number and size of motor vehicle particulate emissions (PM) at subambient temperatures. The study has two principal objectives. The first is to address the following question: which aspects of the particle sampling, dilution, and size measurement process must be made at the vehicle test temperature to obtain an accurate representation of the PM emissions? The second is to perform a preliminary overview of how subambient temperature operation affects PM emissions from the major classes of current model light duty vehicles. The principal findings are the following: (1) The temperature of the particle size instruments, test cell versus room temperature, has little effect on the measurements. (2) Once the engine has warmed, solid particle (soot) mode emissions in the cold test cell are similar to those at room temperature. The first finding simplifies cold temperature emissionstesting because it allows particle sizing instruments to be placed outside the cold test cell and operated at room temperature. The latter is consistent with the expectation that solid particles are formed in the engine and are therefore relatively unaffected by ambient conditions after engine warm-up. Use of cold dilution air in the room-temperature test cell increases the number and size of nuclei particles; however, the effect of dilution airtemperature was inconclusive in the cold test cell.     

Carbon-nutrient balance hypothesis in within-species phytochemical variation ofSalix lasiolepis

Predictions of the carbon-nutrient balance hypothesis were tested using a study of within-species phytochemical variation in the arroyo willow,Salix lasiolepis. The prediction that a balance between nutrients (total protein) and carbon-based secondary metabolites (total phenols) should exist was supported using water treatment and fertilizer experiments and wild willow clones. Leaf nitrogen content and net photosynthetic rates of plants potted in soil in which parental plants grew was low, indicating that wild plants exist under relatively low nutrient status-high carbon balance conditions. The hypothesis also correctly predicted positive relationships between shoot length and phenols in glasshouse plants, wild plants, and plants in the water treatment experiment and negative relationships between shoot length and phenols in the fertilizer treatment experiment. Total phenolic glycosides, fragilin, picein, salicortin, tremulacin, and tremuloidin all correlated positively with shoot length in glasshouse plants on a carbon-biased balance, and male willows had generally lower levels of phenolic glycosides than females. Salicortin and tremulacin showed the strongest positive relationships with shoot length.     

Evaluation of structural defects in brazed ceramic-to-metal joints with C-mode scanning acoustic microscopy

Structural defects and the integrity of brazed aluminium nitride-to-metal joints were studied by using C-mode scanning acoustic microscopy. Lack of bonding, cracks at the nitride/braze interface and surface opening cracks were clearly detected. The comparison of C-SAM results with those of scanning electron microscopy showed good correlation and demonstrated the high resolution of acoustic microscopy especially for detecting surface cracks.     

Crystal fields in ROF:Tb (R = La, Gd)

Laser excited luminescence and site selective excitation spectra of trivalent terbium (Tb³⁺) in two rare earth oxyfluoride (ROF) matrices, LaOF and GdOF, were detected at temperatures down to liquid helium. From the analyses of spectra, the crystal field (c.f.) fine structure of the ⁷F_J (J=0–6) ground multiplet was obtained for the 4f⁸ electron configuration. The energy level schemes comprising 26 c.f. sublevels out of 33 allowed for the C_3v point symmetry of the R³⁺ site were simulated according to a phenomenological model taking into account only the c.f. effect.

The simulation including six c.f. parameters (B₀², B₀⁴, B₃⁴, B₀⁶, B₃⁶, and B₆⁶) reproduced the experimental energy level schemes in a satisfactory manner with rms deviations of 5 and 6 cm⁻¹ for the LaOF and GdOF hosts, respectively. The c.f. parameter sets are characterized by B₀² values close to zero while the fourth and sixth rank parameters assumed rather high values. The O_h to C_3v descending symmetry method revealed a slight trigonal distortion from the cubic fluorite CaF₂-type structure. The c.f. parameters vary only slightly as a function of the host matrix. The ⁷F₆ level was not simulated correctly probably because of the electron–phonon interaction.     

Missing values: how many can they be to preserve classification reliability?

Using five medical datasets we detected the influence of missing values on true positive rates and classification accuracy. We randomly marked more and more values as missing and tested their effects on classification accuracy. The classifications were performed with nearest neighbour searching when none, 10, 20, 30% or more values were missing. We also used discriminant analysis and naïve Bayesian method for the classification. We discovered that for a two-class dataset, despite as high as 20–30% missing values, almost as good results as with no missing value could still be produced. If there are more than two classes, over 10–20% missing values are probably too many, at least for small classes with relatively few cases. The more classes and the more classes of different sizes, a classification task is the more sensitive to missing values. On the other hand, when values are missing on the basis of actual distributions affected by some selection or non-random cause and not fully random, classification can tolerate even high numbers of missing values for some datasets.     

Sampling Conditions for the Measurement of Nucleation Mode Particles in the Exhaust of a Diesel Vehicle

A novel porous tube diluter was characterized to define sampling parameters for repeatable measurements of nucleation-mode particles (NMPs) in the exhaust of a modern diesel passenger car at moderate engine load. This porous tube diluter permits the variation of sampling parameters independently and in a wide range. We investigated the sampling parameters: primary dilution temperature (PDT; 15–55°C), primary dilution ratio (PDR; 8–45), residence time (RT; 0.5–4.0 s), and relative humidity of primary dilution (PRH; 5–90%). Decreased PDT and increased PRH led to a growth of particle number and size in the nucleation mode. While a maximum number of NMPs was found at moderate PDRs between 20 and 30, a maximum volume of NMPs was achieved at PDRs below 20. Coagulation explains the number reduction of NMPs under sampling conditions of prolonged RT and decreased PDR. However, the size growth of the nucleation mode can only partly be attributed to coagulation, and thus growth due to organic compounds from the exhaust probably plays an important role. Sensitivity analysis was conducted as a function of PDR-PDT and revealed two optimal sampling conditions for repeatable NMPs in number or repeatable maximum NMPs in volume. In addition to the sampling parameters, exhaust line conditioning was found to affect NMPs strongly and thus needs to be controlled to minimize effects on the history of measurements.