14985315
Spin-transfer torque magnetoresistive content addressable memory (CAM) cell structure design with enhanced search noise margin
This paper presents a new memory cell structure for content addressable memory (CAM) based on magnetic tunneling junction (MTJ). Each CAM cell uses a pair of differential MTJs as basic storage element and incorporates transistors to greatly improve the cell search noise margin at low sensing current. Using the same design principle, we further develop an area-efficient cell structure for ternary CAM (TCAM), which occupies about 25% less area compared with directly using two CAM cells to form one TCAM cell. The effectiveness of the proposed CAM and TCAM cell structures has been demonstrated by circuit simulation at 0.18 mum CMOS technology.
17935039
Data manipulation techniques to reduce phase change memory write energy
Due to its great scalability potential, phase change memory has become a topic of great current interest. However, high write energy consumption appears to be one of the biggest challenges to be tackled before phase change memory can be adopted as a mainstream memory technology. This paper presents architecture level technique to reduce phase change memory write energy consumption through data manipulations. Motivated by the fact that phase change memory read incurs much less energy than write and write of different value to a phase change memory cell incurs largely different energy, we present two memory write data manipulation techniques that can effectively reduce the overall memory write energy consumption. Their effectiveness has been demonstrated based on mathematical analysis and computer system simulation using phase change memory as the main memory in the computer memory hierarchy. Significant energy savings with up to more than 60% have been shown over a wide range of computer system benchmarks.
30164221
Limited feedback design for MIMO broadcast channels with ARQ mechanism
We investigate the design of a limited feedback mechanism for multiple-input-multiple-output (MIMO) broadcast systems that are equipped with automatic repeat request (ARQ) capabilities. Given multiple antennas at the base-station (BS) and single antenna subscribers, we focus on maximizing the ergodic system sum capacity and propose an adaptive feedback bit allocation scheme under the constraint of total feedback bandwidth. Furthermore, we develop two efficient feedback allocation schemes based on asymptotic analysis. We present simulation results that verify the effectiveness of the proposed adaptive allocation schemes.
2644615
3D finite element mesh generation of complicated tooth model based on CT slices
An interactive three-dimensional finite element generation method is presented for modelling a multi-connected teeth and mandible structure. The tetrahedron is chosen as the basic element type due to its rigorous adaptability to structures with geometric complexities. The mesh generation is implemented by allocating two quadrangles in adjacent CT image slices to form a set of tetrahedrons. By examining all the possible allocations and their degradations, an algorithm is developed for interactive mesh generation, resulting in a series of tetrahedrons consistent with all the others without overlapping and spacing. The developed system was applied to a tooth-mandibular structure, generating a complicated 3D FEM model consisting of 4762 nodes and 18,534 tetrahedral elements with nine different materials. This 3D model was successfully used to evaluate different tooth restoration strategies, which proved the viability and effectiveness of the proposed method.
16516835
Efficient user Scheduling under Low Rate Feedback for Correlated MIMO Broadcast Channels
This paper investigates the scheduling of user signals in MIMO systems with spatially correlated channels. By maximizing an upper bound of the sum capacity, we propose a scheduling scheme which requires only a single scalar feedback from each receiving user. To further reduce the need for user information feedback and better explore the spatial correlation information, a more efficient scheduling method is also developed. This new approach only requires a 1-bit indicator from each user and selects users according to the slowly varying MIMO channel correlation information. Numerical results verify the effectiveness of our proposed schemes.
12613317
Research on the Status Quo and System Architecture of the Web Information Resource Evaluation
Web information resource evaluation (website evaluation) becomes more and more important, as the web information resources become larger and more complex. Thus, a lot of theory and methods have been developed to evaluate websites. In this paper, the author analyzes the primary methods applied currently in the evaluation of the web information resource and points out the main problems in this area from the perspectives of qualitative evaluation, quantitative evaluation, synthetic evaluation and automatic evaluation, after making an in-depth and comprehensive research of the literature and evaluation tools at home and abroad. Furthermore, the paper concludes that the evaluation of information resource on the Internet should take the internal and external characteristics into consideration, in the meantime, the paper puts forward a system architecture scheme of the automatic website evaluation based on the usability engineering.
38900432
Fast (Structured) Newton Computations
Many vector-valued functions, representing expensive computations, are also structured computations. In this case the calculation of the Newton step can be greatly accelerated by exploiting this structure. It is often not necessary, nor economic, to form the true Jacobian in the process of computing the Newton step; instead, a more cost-effective auxiliary Jacobian matrix is used. This auxiliary matrix can be sparse even when the true Jacobian matrix is dense; consequently, sparse matrix technology can be used, to great speed advantage, both in forming the auxiliary matrix and in solving the auxiliary linear system.