1171693
A direct LDA algorithm for high-dimensional data - with application to face recognition
However, for a task with very high dimensional data such as images, the traditional LDA algorithm encounters several difficulties. Consider face recognition for example. A low-definition face image of size 64 by 64 implies a feature space of 64 × 64 = 4096 dimensions, and therefore scatter matrices of size 4096 × 4096 = 16M. First, it is computationally challenging to handle big matrices (such as computing eigenvalues). Second, those matrices are almost always singular, as the number of training images needs to be at least 16M for them to be non-degenerate. Due to these difficulties, it is commonly believed that a direct LDA solution for such high-dimensional data is infeasible. Thus, ironically, before LDA can be used to reduce dimensionality, another procedure has to be first applied for dimensionality reduction. In face recognition, many techniques have been proposed (For a good review, see [2]). Among them, the most notable is a two-stage PCA+LDA approach [4,1]:
6880755
Implicit Trajectory Modeling through Gaussian Transition Models for Speech Recognition
It is well known that frame independence assumption is a fundamental limitation of current HMM based speech recognition systems. By treating each speech frame independently, HMMs fail to capture trajectory information in the acoustic signal. This paper introduces Gaussian Transition Models (GTM) to model trajectories implicitly. Comparing to alternative approaches, such as segment modeling and parallel path HMM, GTM has the advantage that it integrates seamlessly with the HMM frame-work; it can model a large number of trajectories and there is no need to define a topology a priori. Preliminary experiments on Switchboard, a large vocabulary conversational speech recognition task, have shown promising results.
9764475
Towards a multimodal meeting record
Face-to-face meetings usually encompass several modalities including speech, gesture, handwriting, and person identification. Recognition and integration of each of these modalities is important to create an accurate record of a meeting. However, each of these modalities presents recognition difficulties. Speech recognition must be speaker and domain independent, have low word error rates, and be close to real time to be useful. Gesture and handwriting recognition must be writer independent and support a wide variety of writing styles. Person identification has difficulty with segmentation in a crowded room. Furthermore, in order to produce the record automatically, we have to solve the assignment problem (who is saying what), which involves people identification and speech recognition. This paper examines a multimodal meeting room system under development at Carnegie Mellon University that enables us to track, capture and integrate the important aspects of a meeting from people identification to meeting transcription. Once a multimedia meeting record is created, it can be archived for later retrieval.
31039691
Hybrid checkpointing protocol based on selective-sender-based message logging
This paper presents a hybrid checkpointing protocol-an asynchronous checkpointing protocol using a message sending/receiving state change for reducing the overhead of failure-free operation combined with a selective sender-based message logging protocol for reducing the cascade rollback of asynchronous checkpointing protocol. The selective sender-based message logging protocol records only potential orphan messages when taking a checkpoint. And this paper presents a message dependency tree recording the inter-process message sending/receiving information on a volatile storage for reducing the search time of inter-process information during the failure recovery.
7168030
Minimal skew clock embedding considering time variant temperature gradient
The existing temperature-aware clock embedding assumes a time-invariant temperature gradient. However, it is not solved how to find the worst-case temperature gradient leading to the worst case skew. In this paper, we develop a PErturbation based Clock Optimization(PECO) considering the time-variant temperature gradient. For a given clock topology, we minimizethe worst case skew without asking for the worst case temperature map. We decide the merging point level by level based on the sensitivity of the skew with respect to the change of merging point. Such sensitivity is calculated using a parameterized model, which is compressed by a singular-value-decomposition (SVD) and K-meansbased clustering considering the temperature correlation. The experimental results show that our algorithm reduces worst-case skew by up to 5X compared to the existing zero skew based ZST/DME method with small (up to 1%) wirelength overhead.
15665141
An incremental genetic algorithm approach to multiprocessor scheduling
We have developed a genetic algorithm (GA) approach to the problem of task scheduling for multiprocessor systems. Our approach requires minimal problem specific information and no problem specific operators or repair mechanisms. Key features of our system include a flexible, adaptive problem representation and an incremental fitness function. Comparison with traditional scheduling methods indicates that the GA is competitive in terms of solution quality if it has sufficient resources to perform its search. Studies in a nonstationary environment show the GA is able to automatically adapt to changing targets.
16750086
Supporting transactional cache consistency in mobile database systems
In a mobile computing environment, caching of frequently accessed data has been shown to be a useful technique for reducing contention on the narrow bandwidth of the wireless channels. However, the traditional client/server strategies for supporting transactional cache consistency that require extensive communications between a client and a server are not appropriate in a mobile computing environment. In this paper, we propose a new protocol, called OCC-UTS (Optimisitic Concurrency Control with Update TimeStamp), to support transactional cache consistency in a wireless mobile computing environment by utilizing the broadcast-based solutions for the problem of invalidating caches. The consistency check on accessed data and the commitment protocol are implemented in a truly distributed fashion as an integral part of cache invalidation process, with most burden of consistency check being downloaded to mobile clients. Also, our esperiments based on an analytical model substantiate the basic idea and study the performance characteristics. Experimental results show that OCC-UTS protocol without local cache outperforms other competitor protocol, and the more frequent a mobile client accesses data items the more efficient OCC-UTS protocol with local cache is. With respect to disconnection, a mobile client aborts its transaction if it disconnects more than the invalidation broadcast window size. Thus, the tolerance to disconnection is improved if the invalidation broadcast window size is extended.
13464702
Building replicated Internet services using TACT: a toolkit for tunable availability and consistency tradeoffs
An ultimate goal for modern Internet services is the development of scalable, high-performance, highly-available and fault-tolerant systems. Replication is an important approach to achieve this goal. However replication introduces the issue of consistency among replicas, which is further complicated by network partitions. Generally, higher consistency levels result in lower system availability in the presence of network partitions. Thus, there is a fundamental tradeoff between consistency and availability in building replicated Internet services. We argue that Internet services can benefit from dynamically choosing availability/consistency tradeoffs. With three consistency metrics, Unseen Writes, Uncommitted Writes and Staleness, we show how consistency can be meaningfully quantified for many Internet services. We present the design of the TACT (Tunable Availability and Consistency Tradeoffs) toolkit that allows Internet services to flexibly and dynamically choose their own availability/consistency, tradeoffs, enabling differentiated availability/consistency quality of service. Further TACT makes it possible for Internet services to dynamically trade consistency for performance.