3513935
A dynamic mechanism for time-constrained trading
The market mechanism design is important for both conventional and electronic commerce as it affects the fairness and efficiency of trading. In this paper, we propose a new market mechanism for time- constrained trading. Our mechanism mimics the traditional brokering system, where buyers and sellers meet together and negotiate through an electronic marketplace. At each time step, agents are paired up for negotiating a deal. We consider that buyer and seller agents are associated with a time constraint and a search cost, and thus must decide promptly and judiciously whether to accept an offer. One distinguishing feature of our mechanism is that the marketplace provides buyer and seller agents with statistical information about the goods. Specifically, the statistics include the probability distributions of obtaining and losing a particular offer. With this information, the agents' decision can be viewed as a Markov decision process, and the optimal (dominant) trading strategy can be computed. In other words, buyer and seller agents can make trading decisions that maximize their expected utility without the need of speculating others actions. We also explain how such a dominant strategy can be computed in an efficient manner. Another distinguishing feature of the proposed mechanism is that the statistics are updated continuously and hence the dominant trading strategy is adaptive. Experimental results verify that our mechanism facilitates a fair allocation to the trading agents under various demand and supply conditions.
858957
Hidden-Mode Markov Decision Processes for Nonstationary Sequential Decision Making
Problem formulation is often an important first step for solving a problem effectively. In sequential decision problems, Markov decision process (MDP) ([2]; [22]) is a model formulation that has been commonly used, due to its generality, flexibility, and applicability to a wide range of problems. Despite these advantages, there are three necessary conditions that must be satisfied before the MDP model can be applied; that is, 
 
1. 
 
The environment model is given in advance (a completely-known environment). 
 
 
 
 
2. 
 
The environment states are completely observable (fully-observable states, implying a Markovian environment). 
 
 
 
 
3. 
 
The environment parameters do not change over time (a stationary environment).
19996434
A multi-material virtual prototyping system
Abstract This paper proposes a multi-material virtual prototyping system for digital fabrication of heterogeneous prototypes. It consists mainly of a topological hierarchy-sorting algorithm for processing slice contours, and a virtual simulation system for visualisation and optimisation of multi-material layered manufacturing (MMLM) processes. The topological hierarchy-sorting algorithm processes the hierarchy relationship of complex slice contours. It builds a parent-and-child list that defines the containment relationship of the slice contours, and subsequently arranges the contours in an appropriate sequence, which facilitates toolpath planning for MMLM by avoiding redundant tool movements. The virtual simulation system simulates MMLM processes and provides stereoscopic visualisation of the resulting multi-material prototypes for quality analysis and optimisation of the processes.
9484226
Group-based dynamic computational replication mechanism in peer-to-peer grid computing
A peer-to-peer grid computing is complicated by heterogeneous capabilities, failures, volatility, and lack of trust because it is based on desktop computers at the edge of the Internet. In order to improve the reliability of computation and gain better performance, a replication mechanism must adapt to these distinct features. In other words, it is required to classify volunteers into groups that have similar properties and then dynamically apply different replication algorithms to each group. However, existing mechanisms do not provide such a replication mechanism on a per group basis. As a result, they cause a high overhead and poor performance. To solve the problems, we propose a new group-based computational replication mechanism to adapt to an unstable, untrusted, dynamic peer-to-peer grid computing environment. Our mechanism can reduce the number of redundancy and therefore complete many tasks by adaptively replicating computations on the basis of the properties of volunteer group such as availability, credibility, and volunteering service time
6005789
Optimizing SMT Processors for High Single-Thread Performance
Simultaneous Multithreading (SMT) processors achieve high processor throughput at the expense of single-thread performance. This paper investigates resource allocation policies for SMT processors that preserve, as much as possible, the single-thread performance of designated “foreground” threads, while still permitting other “background” threads to share resources. Since background threads o ns uch an SMT machine have an ear-zero performance impact on foreground threads, we refer to the background threads as transparent threads. Transparent threads are ideal for performing low-priority or non-critical computations, with applications in process scheduling, subordinate multithreading, and on-line performance monitoring. To realize transparent threads, we propose three mechanisms for maintaining the transparency of background threads: slot prioritization, background thread instruction-window partitioning, and background thread flushing. In addition, we propose three mechanisms to boost background thread performance without sacrificing transparency: aggressive fetch partitioning, foreground thread instruction-window partitioning, and foreground thread flushing. We implement our mechanisms on a detailed simulator of an SMT processor, and evaluate them using 8 benchmarks, including 7 from the SPEC CPU2000 suite. Our results show when cache and branch predictor interference are factored out, background threads introduce less than 1% performance degradation on the foreground thread. Furthermore, maintaining the transparency of background threads reduces their throughput by only 23% relative to an equal priority scheme. To demonstrate the usefulness of transparent threads, we study Transparent Software Prefetching (TSP), an implementation of software data prefetching using transparent threads. Due to its near-zero overhead, TSP enables prefetch instrumentation for all loads in a program, eliminating the need for profiling. TSP, without any profile information, achieves a 9.41% gain across 6 SPEC benchmarks, whereas conventional software prefetching guided by cache-miss profiles increases performance by only 2.47%.
10832557
Adaptive group scheduling mechanism using mobile agents in peer-to-peer grid computing environment
Peer-to-peer grid computing is an attractive computing paradigm for high throughput applications. However, both volatility due to the autonomy of volunteers (i.e., resource providers) and the heterogeneous properties of volunteers are challenging problems in the scheduling procedure. Therefore, it is necessary to develop a scheduling mechanism that adapts to a dynamic peer-to-peer grid computing environment. In this paper, we propose a Mobile Agent based Adaptive Group Scheduling Mechanism (MAAGSM). The MAAGSM classifies and constructs volunteer groups to perform a scheduling mechanism according to the properties of volunteers such as volunteer autonomy failures, volunteer availability, and volunteering service time. In addition, the MAAGSM exploits a mobile agent technology to adaptively conduct various scheduling, fault tolerance, and replication algorithms suitable for each volunteer group. Furthermore, we demonstrate that the MAAGSM improves performance by evaluating the scheduling mechanism in Korea@Home.
7326399
A Scalable Update Management Mechanism for Query Result Caching Systems at Database-Driven Web Sites
A key problem in using caching technology for dynamic contents lies in update management. An update management scheme should be very efficient without imposing much extra burden to the system, especially to the original database server. We propose an scalable update management mechanism for query result caching in database-backed Web sites. Our mechanism employs a two-phase consistency checking method, which prunes out unaffected queries at the earliest possible moment. The method scales well with a high number of cached instances.