Bounded-distance multi-clusterhead formation in wireless ad hoc networks

We present a clustering technique addressing redundancy for bounded-distance clusters, which means being able to determine the minimum number of cluster-heads per node, and the maximum distance from nodes to their cluster-heads. This problem is similar to computing a (k, r)-dominating set, (k, r)-DS, of the network. (k, r)-DS is defined as the problem of selecting a minimum cardinality vertex set D of the network such that every vertex u not in D is at a distance smaller than or equal to r from at least k vertices in D. In mobile ad hoc networks (MANETs), clusters should be computed distributively, because the topology may change frequently. We present the first centralized and distributed solutions to the (k, r)-DS problem for arbitrary topologies. The centralized algorithm computes a (k · ln Δ)-approximation, where Δ is the largest cardinality among all r-hop neighborhoods in the network. The distributed approach is extended for clustering applications, while the centralized is used as a lower bound for comparison purposes. Extensive simulations are used to compare the distributed solution with the centralized one. As a case study, we propose a novel multi-core multicast protocol that applies the distributed solution for the election of cores. The new protocol is compared against PUMA, one of the best performing multicast protocols for MANETS. Simulation results show that the new protocol outperforms PUMA on the context of static networks.     

低能量系统在时间限制下的同时通讯和处理器频率选择

This paper presents a method to reduce the energy consumption of multi-core systems characterized by processor cores and buses with discrete frequency levels under timing constraints. The proposed method takes the transformations of the original task graphs, which include dependent tasks located in different iterations, as inputs. The proposed method utilizes mapping selection as well as joint processor and communication frequency scaling to implement energy reduction. We conduct experiments on several random task graphs. Experimental results show that the proposed method can achieve substantial energy reduction compared with previous work under the same hard timing constraints.     

Increasing data locality and introducing Level-3 BLAS in the Neville elimination

In this paper we present two new algorithmic variants to compute the Neville elimination, with and without pivoting, which improve data locality and cast most of the computations in terms of high-performance Level 3 BLAS. The experimental evaluation on a state-of-the-art multi-core processor demonstrates that the new blocked algorithms exhibit a much higher degree of concurrency and better cache usage, yielding higher performance while offering numerical accuracy akin to that of the traditional columnwise variant in most cases.     

Combining Coarse-Grained Software Pipelining with DVS for Scheduling Real-Time Periodic Dependent Tasks on Multi-Core Embedded Systems

In this paper, we combine coarse-grained software pipelining with DVS (Dynamic Voltage/Frequency Scaling) for optimizing energy consumption of stream-based multimedia applications on multi-core embedded systems. By exploiting the potential of multi-core architecture and the characteristic of streaming applications, we propose a two-phase approach to solve the energy minimization problem for periodic dependent tasks on multi-core processors with discrete voltage levels. With our approach, in the first phase, we propose a coarse-grained task-level software pipelining algorithm called RDAG to transform the periodic dependent tasks into a set of independent tasks based on the retiming technique (Leiserson and Saxe, Algorithmica 6:5–35, 1991). In the second phase, we propose two DVS scheduling algorithms for energy minimization. For single-core processors, we propose a pseudo-polynomial algorithm based on dynamic programming that can achieve optimal solution. For multi-core processors, we propose a novel scheduling algorithm called SpringS which works like a spring and can effectively reduce energy consumption by iteratively adjusting task scheduling and voltage selection. We conduct experiments with a set of benchmarks from E3S (Dick 2008) and TGFF () based on the power model of the AMD Mobile Athlon4 DVS processor. The experimental results show that our technique can achieve 12.7% energy saving compared with the algorithms in Zhang et al. (2002) on average.

多核DSP芯片C6678引导过程的研究与实现

多核数字信号处理(DSP)芯片给信号处理能力带来了质的提升,TI公司推出的TMS320C6678是一款具有代表性的高性能多核DSP芯片。引导技术是DSP应用的关键技术之一。C6678有着丰富的外设接口,可选择多种引导设备,同时由于多核的存在,引导过程变得更为复杂。文中对C6678的引导方式进行了透彻的研究,介绍了C6678多核引导过程的具体实现步骤,对C6678引导程序的开发提供了实际的方法和经验。     

Enrichment of Fetal Nucleated Red Blood Cells by Multi-core Magnetic Composite Particles for Non-invasive Prenatal Diagnosis

A novel kind of multi-core magnetic composite particles, the surfaces of which were respectively modified with goat-anti-mouse IgG and antitransferrin receptor(anti-CD71), was prepared. The fetal nucleated red blood cells(FNRBCs) in the peripheral blood of a gravida were rapidly and effectively enriched and separated by the modified multi-core magnetic composite particles in an external magnetic field. The obtained FNRBCs were used for the identification of the fetal sex by means of fluorescence in situ hybridization(FISH) technique. The results demonstrate that the multi-core magnetic composite particles meet the requirements for the enrichment and speration of FNRBCs with a low concentration and the accuracy of detetion for the diagnosis of fetal sex reached to 95%. Moreover, the obtained FNRBCs were applied to the non-invasive diagnosis of Down syndrome and chromosome 3p21 was detected. The above facts indicate that the novel multi-core magnetic composite particles-based method is simple, reliable and cost-effective and has opened up vast vistas for the potential application in clinic non-invasive prenatal diagnosis.     

RF-TSV design, modeling and application for 3D multi-core computer systems

The state-of-the-art multi-core computer systems are based on Very Large Scale three Dimensional (3D) Integrated circuits (VLSI). In order to provide high-speed vertical data transmission in such 3D systems, efficient Through-Silicon Via (TSV) technology is critically important. In this paper, various Radio Frequency (RF) TSV designs and models are proposed. Specifically, the Cu-plug TSV with surrounding ground TSVs is used as the baseline structure. For further improvement, the dielectric coaxial and novel air-gap coaxial TSVs are introduced. Using the empirical parameters of these coaxial TSVs, the simulation results are obtained demonstrating that these coaxial RF-TSVs can provide two-order higher of cut-off frequencies than the Cu-plug TSVs. Based on these new RF-TSV technologies, we propose a novel 3D multi-core computer system as well as new architectures for manipulating the interfaces between RF and baseband circuit. Taking into consideration the scaling down of IC manufacture technologies, predictions for the performance of future generations of circuits are made. With simulation results indicating energy per bit and area per bit being reduced by 7% and 11% respectively, we can conclude that the proposed method is a worthwhile guideline for the design of future multi-core computer ICs.     

达芬奇异构多核处理器核间通信技术研究

针对目前通用的达芬奇异构多核处理器,研究了其ARM核、DSP核以及视频协处理器之间的通信与协作机制.在分析多核处理器核间通信原理的基础上,研究了TMS320DM816x系列达芬奇异构多核处理器的核间通信技术,详细阐述片上核间互联结构与核间通信软件的实现.最后基于SysLink底层通信模块设计了多路高清音视频应用系统,对核间通信进行验证.系统可充分发挥各处理核的性能,实现了各核间的高效协作.