16926226
Optimal histogram matching by monotone gray level transformation
This paper investigates the problem of optimal histogram matching using monotone gray level transformation, which always assigns all picture points of a given gray level <italic>i</italic> to another gray level <italic>T</italic>(<italic>i</italic>) such that if <italic>i</italic> ≥ <italic>j</italic>, then <italic>T</italic>(<italic>i</italic>) ≥ <italic>T</italic>(<italic>j</italic>). The objective is to find a transformed digital picture of a given picture such that the sum of absolute errors between the gray level histogram of the transformed picture and that of a reference picture is minimized. This is equivalent to placing <italic>k</italic>1 linearly ordered objects of different sizes one by one into <italic>k</italic>2 linearly ordered boxes of assorted sizes, such that the accumulated error of space underpacked or overpacked in the boxes is minimized; the placement function is monotonic, which ensures a polynomial time solution to this problem. A tree search algorithm for optimal histogram matching is presented which has time complexity <italic>O</italic>(<italic>k</italic>1 × <italic>k</italic>2). If the monotone property is dropped, then the problem becomes <italic>NP</italic>-complete, even if it is restricted to <italic>k</italic>2 = 2.
35519508
Extending Visual Languages for Multimedia
Visual languages, which let users customize iconic sentences, can be extended to accommodate multimedia objects, letting users access media dynamically. Teleaction objects, or multimedia objects with knowledge structures, can be designed using visual languages to automatically respond to events and perform tasks like "find related books" in a virtual library.
39945679
Iconic Language Design for People with Significant Speech and Multiple Impairments
15816324
Multi-level specification and protocol design for distributed multimedia communication
The major challenge in the design of an efficient distributed multimedia system is the integration and support of a wide variety of applications. Investigating the basic issues involved in the design and specification of distributed muttimcdia systems is the focus of this paper. A basic layered network architecture is proposed as the uniform framework for the investigation of different levels of functionality typically associated with the communication network that supports multimedia communication. Within this framework, we propose to identify the communication requirements for multimedia applications and characterize a set of communication primitives which specify different qualities of scrvicc to reflect different real-time rcquircmcnts. ‘Ilis investigation is guided by an efficient and flexible multi-level specification model. We will characterize this model and show that the model can be amenable to the construction of a set of communication primitives that support synchronization and communication of multimedia applications.
17298481
Iconic language design for people with significant speech and multiple impairments
We present an approach of iconic language design for people with significant speech and multiple impairments (SSMI), based upon the theory of Icon Algebra and the theory of Conceptual Dependency (CD) to derive the meaning of iconic sentences. An interactive design environment based upon this methodology is described.
34016873
Parsing 2D Languages by a Pictorial GLR Parser
44449006
Online and semi-online scheduling of two machines under a grade of service provision
We consider the online scheduling of two machines under a grade of service (GoS) provision and its semi-online variant where the total processing time is known. Respectively for the online and semi-online problems, we develop algorithms with competitive ratios of 53 and 32 which are shown to be optimal.
17634440
An optimal cache algorithm for streaming VBR video over a heterogeneous network
High quality video content for on-demand services is usually stored and streamed in a compressed format with a VBR (variable bit rate) property; however, the streaming traffic is extremely bursty. If there is no client buffer to regulate the video's delivery, the backbone WAN (wide area network) bandwidth needs to allocate the video's peak bit rate to guarantee playback quality. To reduce the bandwidth requirement in the backbone WAN, previous researchers have proposed a Video Staging Mechanism to cache portions of the video in a video proxy close to clients. In this paper, we propose a very effective OC (optimal cache) algorithm to handle the Video Staging Mechanism and prove theoretically that the proxy cache computed by our OC algorithm for each video is minimal when all other resources remain constant. On the basis of experiment results, we cache the least amount of video data in the video proxy by using the OC algorithm, and reduce the WAN bandwidth requirement by an amount equal to that of conventional algorithms. In contrast, given the equal size of the storage in a video proxy, the OC algorithm reduces the bandwidth requirement in the backbone WAN much more than conventional algorithms.
43612588
Priority-Based Internet Access Control for Fairness Improvement and Abuse Reduction
In this paper, we exploit a prioritized-service architecture and apply a priority based traffic control scheme to reduce abusive Internet access, improve fairness among users and study users' behavior under a prioritized service for Internet access. The Internet access by dormitory users of National Taiwan University (NTU) serves as a conveyer problem. There are two classes of service. The regular class has a volume quota for each user, which is designed to meet majority users' essential demands while limiting abusive usage of quality service. The custody class is lower in service priority with no volume quota limitation. Our mathematical models for design and analysis include individual and aggregate user demand models and a network performance model. The priority control scheme is implemented over an existing NTU dormitory network with additions of a QoS router, a meter reading server, an accounting server and a user interface server. The control leads to 48.9% reduction in average packet drop rate, 42.2% improvement in a fairness measure, reduction of abusive Internet access by 57.82% and 145.09% Internet access increase in majority users. Such results are quite consistent with predictions of our mathematical models.
16824799
A heuristic method for self‐healing ring design in a single‐homing cluster
In this paper, we consider a SONET (Synchronous Optical NETwork) USHR (Uni‐directional Self‐Healing Ring) design problem for a single‐homing cluster, i.e., a cluster with a single designated hub. The problem is formulated as a nonlinear integer programming problem and a branch and bound heuristic method based on the Lagrangian relaxation and subgradient optimization technique is proposed to handle the problem. In solving any ring design problem, we should deal with two different aspects of the ring design, namely, the ring routing aspect and the ring loading aspect. Both of these two aspects are well integrated and represented in our model. Such an integrated formulation has not been proposed in the existing literature mainly due to its computationally intractable complexity. In order to cope with such complexity, a preprocessing technique for reducing the complexity and several branch and bound strategies are proposed. The efficiency of the proposed method is tested through computational experiments. For the computational experiments, test problems are generated using the data obtained from the actual topologies in Seoul, Korea. The computational experiments show that the proposed method yields near‐optimum designs within reasonable computation time.
15655721
The Worst-case Analysis of the MULTIFIT Algorithm for Scheduling Nonsimultaneous Parallel Machines
Abstract In this paper we consider the nonsimultaneous multiprocessor scheduling problem, or NMSP for short. The NMSP is a makespan minimization scheduling problem which involves the nonpreemptive assignment of independent jobs on m parallel machines with different starting times. It is well known that the longest processing time (LPT) algorithm and the modified LPT(MLPT) algorithm yield schedules with makespans bounded by 3 2 − 1 2m and 4/3 times the optimum makespan, respectively. In this paper, we show that the best known worst-case performance bound, 4/3 of the MLPT, is tight by constructing a worst-case example. Then, we employ the bin-packing heuristic algorithm called the MULTIFIT to solve the NMSP and show that the makespan of the schedule generated by the MULTIFIT algorithm is bounded by 9/7+2−k times the optimum makespan, where k is the selected number of the major iterations in the MULTIFIT. This worst-case bound of the MULTIFIT algorithm is, so far, the best bound for the NMSP and the tightness of the bound is still an open question.