379901
Answering linear optimization queries with an approximate stream index
We propose a SAO index to approximately answer arbitrary linear optimization queries in a sliding window of a data stream. It uses limited memory to maintain the most “important” tuples. At any time, for any linear optimization query, we can retrieve the approximate top-K tuples in the sliding window almost instantly. The larger the amount of available memory, the better the quality of the answers is. More importantly, for a given amount of memory, the quality of the answers can be further improved by dynamically allocating a larger portion of the memory to the outer layers of the SAO index.
53228070
Transaction reordering with application to synchronized scans
Traditional workload management methods mainly focus on the current system status while information about the interaction between queued and running transactions is largely ignored. An exception to this is the transaction reordering method, which reorders the transaction sequence submitted to the RDBMS and improves the transaction throughput by considering both the current system status and information about the interaction between queued and running transactions. The existing transaction reordering method only considers the reordering opportunities provided by analyzing the lock conflict information among multiple transactions. This significantly limits the applicability of the transaction reordering method. In this paper, we extend the existing transaction reordering method into a general transaction reordering framework that can incorporate various factors as the reordering criteria. We show that by analyzing the resource utilization information of transactions, the transaction reordering method can also improve the system throughput by increasing the resource sharing opportunities among multiple transactions. We provide a concrete example on synchronized scans and demonstrate the advantages of our method through experiments with a commercial parallel RDBMS.
14863037
Resource-adaptive real-time new event detection
In a document streaming environment, online detection of the first documents that mention previously unseen events is an open challenge. For this online new event detection (ONED) task, existing studies usually assume that enough resources are always available and focus entirely on detection accuracy without considering efficiency. Moreover, none of the existing work addresses the issue of providing an effective and friendly user interface. As a result, there is a significant gap between the existing systems and a system that can be used in practice. In this paper, we propose an ONED framework with the following prominent features. First, a combination of indexing and compression methods is used to improve the document processing rate by orders of magnitude without sacrificing much detection accuracy. Second, when resources are tight, a resource-adaptive computation method is used to maximize the benefit that can be gained from the limited resources. Third, when the new event arrival rate is beyond the processing capability of the consumer of the ONED system, new events are further filtered and prioritized before they are presented to the consumer. Fourth, implicit citation relationships are created among all the documents and used to compute the importance of document sources. This importance information can guide the selection of document sources. We implemented a prototype of our framework on top of IBM's Stream Processing Core middleware. We also evaluated the effectiveness of our techniques on the standard TDT5 benchmark. To the best of our knowledge, this is the first implementation of a real application in a large-scale stream processing system.
11663917
On iterative intelligent medical search
Searching for medical information on the Web has become highly popular, but it remains a challenging task because searchers are often uncertain about their exact medical situations and unfamiliar with medical terminology. To address this challenge, we have built an intelligent medical Web search engine called iMed, which uses medical knowledge and an interactive questionnaire to help searchers form queries. This paper focuses on iMed's iterative search advisor, which integrates medical and linguistic knowledge to help searchers improve search results iteratively. Such an iterative process is common for general Web search, and especially crucial for medical Web search, because searchers often miss desired search results due to their limited medical knowledge and the task's inherent difficulty. iMed's iterative search advisor helps the searcher in several ways. First, relevant symptoms and signs are automatically suggested based on the searcher's description of his situation. Second, instead of taking for granted the searcher's answers to the questions, iMed ranks and recommends alternative answers according to their likelihoods of being the correct answers. Third, related MeSH medical phrases are suggested to help the searcher refine his situation description. We demonstrate the effectiveness of iMed's iterative search advisor by evaluating it using real medical case records and USMLE medical exam questions.
5740599
Multi-query SQL Progress Indicators
Recently, progress indicators have been proposed for SQL queries in RDBMSs. All previously proposed progress indicators consider each query in isolation, ignoring the impact simultaneously running queries have on each other’s performance. In this paper, we explore a multi-query progress indicator, which explicitly considers concurrently running queries and even queries predicted to arrive in the future when producing its estimates. We demonstrate that multi-query progress indicators can provide more accurate estimates than single-query progress indicators. Moreover, we extend the use of progress indicators beyond being a GUI tool and show how to apply multi-query progress indicators to workload management. We report on an initial implementation of a multi-query progress indicator in PostgreSQL and experiments with its use both for estimating remaining query execution time and for workload management.
95221
MedSearch: a specialized search engine for medical information retrieval
People are thirsty for medical information. Existing Web search engines often cannot handle medical search well because they do not consider its special requirements. Often a medical information searcher is uncertain about his exact questions and unfamiliar with medical terminology. Therefore, he sometimes prefers to pose long queries, describing his symptoms and situation in plain English, and receive comprehensive, relevant information from search results. This paper presents MedSearch, a specialized medical Web search engine, to address these challenges. MedSearch uses several key techniques to improve its usability and the quality of search results. First, it accepts queries of extended length and reforms long queries into shorter queries by extracting a subset of important and representative words. This not only significantly increases the query processing speed but also improves the quality of search results. Second, it provides diversified search results. Lastly, it suggests related medical phrases to help the user quickly digest search results and refine the query. We evaluated MedSearch using medical questions posted on medical discussion forums. The results show that MedSearch can handle various medical queries effectively and efficiently.
1980102
Dynamic Rate Assignment and Power Control in Uplink UMTSW-CDMA Systems
Power control and rate assignment are important tools to maximize system resource utilization while satisfying quality of service (QoS) in a code division multiple access (CDMA) system. In this paper, we propose an algorithm of simultaneously adapting transmission power and data rate to maximize system throughput and minimize the power consumption in a wideband CDMA (W-CDMA) network. The greedy rate packing (GRP) allocation scheme, where high date rates are assigned to users with favorite channel conditions and lower interference, is employed for the rate adaptation. Compared with the results using Zhao et al. (2005) (algorithm 2), close-loop power control (CLPC) alone, and rate adaptation alone approaches, our proposed power and rate transmission scheme (algorithm 1) significantly improves transmission efficiency
18783200
A Novel Low-Power Clock Skew Compensation Circuit
The clock is a periodic synchronization signal used as a time reference for data transfers in synchronous digital systems. However, the clock skew constrains the improvement of clock frequencies and affects the reliability of systems. One skew reduction technique is the use of clock deskew circuits. They can be classified into two methods: delay-locked loop (DLL) deskewing and synchronous mirror delay (SMD) deskewing. The DLL deskewing achieves a fine accuracy, but suffers from slow locking. Reversely, the adjustment of the SMD deskewing is fast, but suffers from a poor accuracy. In this paper, a low-power full-digital hybrid clock deskew circuit is presented. It uses a SMD as coarse delay line and a digital-DLL as a fine delay line. The SPICE simulation shows that the proposed clock deskew circuit achieves fine accuracy , fast locking, and low power.
62478850
Test generation with respect to distributed interfaces
Abstract In the area of testing communication systems, the interfaces between systems to be tested and their testers have great impact on test generation and fault detectability. Several types of such interfaces have been standardized by the International Standardization Organization (ISO). A general distributed test architecture, containing distributed interfaces, has been presented in the literature for testing distributed systems based on the Open Distributing Processing (ODP) Basic Reference Model (BRM), which is a generalized version of ISO distributed test architecture. We study in this paper the issue of test selection with respect to such a test architecture. In particular, we consider communication systems that can be modeled by finite state machines with several distributed interfaces, called ports. A test generation method is developed for generating test sequences for such finite state machines, which is based on the idea of synchronizable test sequences. We then apply this method to generate test sequences for a so-called quorum protocol. Starting from the initial effort by Sarikaya, a certain amount of work has been done for generating test sequences for finite state machines with respect to the ISO distributed test architecture, all based on the idea of modifying existing test generation methods to generate synchronizable test sequences. However, none studies the fault coverage provided by their methods. We investigate the issue of fault coverage and point out a fact that the methods given in the literature for the distributed test architecture cannot ensure the same fault coverage as the corresponding original testing methods. We also study the limitation of fault detectability in the distributed test architecture.
22377735
Failure-Equivalent Transformation of Transition Systems to Avoid Internal Actions
Abstract Labelled transition systems are often used as a theoretical framework for modelling communication protocols or distributed software systems. In order to model the deadlock properties of the systems, the internal transitions of the submodules are often represented globally by so-called internal actions. However, certain verification and testing methods assume that the specification of the system is given in the form of a transition system without internal actions. This paper shows that most labelled transition systems with internal actions can be transformed into a failure-equivalent labelled transition system without internal actions. A sufficient condition is given, and an algorithm is described which does the transformation for any transition system which satisfies the condition. This algorithm can be applied to use the above verification and testing methods also for specification including internal actions.
15429088
Abnormality detection in automated mass screening system of diabetic retinopathy
An approach to abnormality detection from colour fundus images for an automated mass screening system is proposed in this paper, which uses the object-based colour difference image. Four colour models, viz. RGB, Luv, Lab and HVC, are evaluated based on hand-labelled feature maps, and Luv and Lab are selected for computing the colour difference because of their good performances in object classification. The object-based colour difference images of bright objects (e.g. exudates) and dark objects (e.g. haemorrhages and blood vessels) are obtained respectively according to the 2D histogram distribution on the L-u plane, and then a watershed transform is performed on the colour difference image to extract object candidates. A pre-thresholding and a post-verification procedure are performed to deal with the over-segmentation problem of the watershed transform.