6838561
High Level Indexing of User-Defined Types
35134245
Single Table Access Using Multiple Indexes: Optimization, Execution, and Concurrency Control Techniques
Many data base management systems' query optimizers choose at most one index for accessing the records of a table in a given query, even though many indexes may exist on the table. In spite of the fact that there are some systems which use multiple indexes, very little has been published about the concurrency control or query optimization implications (e.g., deciding how many indexes to use) of using multiple indexes. This paper addresses these issues and presents solutions to the associated problems. Techniques are presented for the efficient handling of record ID lists, elimination of some locking, and determination of how many and which indexes to use. The techniques are adaptive in the sense that the execution strategies may be modified at run-time (e.g., not use some indexes which were to have been used), if the assumptions made at optimization-time (e.g., about selectivities) turn out to be wrong. Opportunities for exploiting parallelism are also identified. A subset of our ideas have been implemented in IBM's DB2 V2R2 relational data base management system.
27987792
The Study and Analysis of Joint Adaptive Clock Recovery Mechanism for TDMoIP
TDM over IP (TDMoIP) is an effective method for transparently transporting time division multiplexed (TDM) signals over IP-based networks. Clock recovery mechanism is essential for it. This paper briefly introduces the Timing requirement and principle of clock recovery, describes an improved adaptive clock recovery mechanism combined with timestamps and buffer data offset, presents the derivational process and analyzes how to deal with IP-based networks characteristics. Finally, the simulation results showed that the performance of this improved clock recovery mechanism can reach a high level and meet the requirement of the TDM service standard.
16403865
Contamination Level and Speciation of Heavy Metals in Sediments from Yundang Lake, Xiamen
Yundang Lake is an important area for living and traveling in Xiamen Island. Severe pollution and sedimentation have been found in the lake, and then the dredging is needed. In order to assess the pollution level of dredged material, sediments from 6 stations in the Yundang Lake were sampled for heavy metal contamination, speciation analysis, and adsorption-desorption experiment in April 2003. Heavy metals concentrations varied from 21.96~848.38 mg/kg for Cu, 51.11~398.25 mg/kg for Pb, 121.60~4301.25 mg/kg for Zn, 0.00~14.71 mg/kg for Cd and 0.70~31.18 mg/kg for total Hg, respectively. The average concentrations of metals (Cu, Zn, Cd, and total Hg) are almost much higher than the secondary standard criteria of national marine sediment quality. According to the mean values of pollution index (Pi), the order of pollution level for heavy metals is as following: Hg ≫Cd ≫Zn ≫Cu ≫Pb. The results from the concentrations and Pi values of selected metals suggest that the study area has been significantly contaminated with heavy metals, and the plan that transferring dredged material to the dumping area must be forbidden. Similar chemical fractionation distribution for each metal is found in the outer lake and Songbai Lake, except for Hg. The main fraction for selected metals is the residual species, except for Cd in station Y17. It indicates that those heavy metals exhibit low biological availability in study area. Both speciation analysis and adsorption-desorption experiment show that the effects on the heavy metals in disposal area resulting from dredging at the Yundang Lake are not significant and the dredged material is fit to be stored at the reclamation region.
60451548
Switching Hypothesized Measurements: A Dynamic Model with Applications to Occlusion Adaptive Joint Tracking
This paper proposes a dynamic model supporting multimodal state space probability distributions and presents the application of the model in dealing with visual occlusions when tracking multiple objects jointly. For a set of hypotheses, multiple measurements are acquired at each time instant. The model switches among a set of hypothesized measurements during the propagation. Two computationally efficient filtering algorithms are derived for online joint tracking. Both the occlusion relationship and state of the objects are recursively estimated from the history of measurement data. The switching hypothesized measurements (SHM) model is generally applicable to describe various dynamic processes with multiple alternative measurement methods.
11056640
Two Further Gradient BYY Learning Rules for Gaussian Mixture with Automated Model Selection
Under the Bayesian Ying-Yang (BYY) harmony learning theory, a harmony function has been developed for Gaussian mixture model with an important feature that, via its maximization through a gradient learning rule, model selection can be made automatically during parameter learning on a set of sample data from a Gaussian mixture. This paper proposes two further gradient learning rules, called conjugate and natural gradient learning rules, respectively, to efficiently implement the maximization of the harmony function on Gaussian mixture. It is demonstrated by simulation experiments that these two new gradient learning rules not only work well, but also converge more quickly than the general gradient ones.
43870484
On parameter-dependent connected components of gray images
Abstract We introduce a new definition of the connected components of gray images which takes into account both the gray values of the pixels and the differences of the gray values of the neighbouring pixels and which depends on two parameters, e and δ. We may adjust the values of the parameters for different types of images or in different levels of image analysis. We analyse a gray image in an intermediate level through the inter-relationships of its (e, δ) components rather than only in the pixel level.