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 Active and Passive Electronic Components , 2004, DOI: 10.1080/08827510310001648915 Abstract: In the automatic placement of integrated circuits, the force directed relaxation (FDR) method [Goto, S. (1981). An efficient algorithm for the two-dimensional placement problem in electrical circuit layout. IEEE Trans. on Circuits and Systems, CAS-28(1), 12-18] is a good iterative optimization algorithm. In this article, an improved force directed relaxation (IFDR) method for standard cell placement is presented, which provides a more flexible and efficient cell location adjustment scheme and a more extensive searching scale for better iterative placement optimization than the FDR method. A new heuristic algorithm based on local optimization is combined with the IFDR method to improve the placement. Experiments on the Microelectronics Center of North Carolina (MCNC) standard cell benchmarks [http://www.cbl.ncsu.edu/pub/Benchmark_ dirs/Layout Synth92/] have been done, and the results show that total wire length is reduced up to 25% and by an average of 16% in comparison with that from the placement algorithm of TimberWolf7.0.
 Sensors , 2009, DOI: 10.3390/s91007664 Abstract: Wireless communication between sensors allows the formation of flexible sensor networks, which can be deployed rapidly over wide or inaccessible areas. However, the need to gather data from all sensors in the network imposes constraints on the distances between sensors. This survey describes the state of the art in techniques for determining the minimum density and optimal locations of relay nodes and ordinary sensors to ensure connectivity, subject to various degrees of uncertainty in the locations of the nodes.
 计算机科学 , 2010, Abstract: Placement legalization removes the overlap among cells after the global placement, and moves the cells to their final position. Macros make legalization harder to resolve in the mixed mode. According to the structure characteristics of macros,and considering the site constraint an algorithm for macros legalization was designed and implemented.The algorithm was tested on mPL6 global placement Experimental results show its reasonable quality compared with FastPlace.
 Computer Science , 2014, Abstract: As the feature size of semiconductor process further scales to sub-16nm technology node, triple patterning lithography (TPL) has been regarded one of the most promising lithography candidates. M1 and contact layers, which are usually deployed within standard cells, are most critical and complex parts for modern digital designs. Traditional design flow that ignores TPL in early stages may limit the potential to resolve all the TPL conflicts. In this paper, we propose a coherent framework, including standard cell compliance and detailed placement to enable TPL friendly design. Considering TPL constraints during early design stages, such as standard cell compliance, improves the layout decomposability. With the pre-coloring solutions of standard cells, we present a TPL aware detailed placement, where the layout decomposition and placement can be resolved simultaneously. Our experimental results show that, with negligible impact on critical path delay, our framework can resolve the conflicts much more easily, compared with the traditional physical design flow and followed layout decomposition.
 Physics , 1996, DOI: 10.1016/S0920-5632(96)90010-9 Abstract: We outline the renormalization of the standard model to all orders of perturbation theory in a way which does not make essential use of a specific subtraction scheme but is based on the Slavnov-Taylor identity. Physical fields and parameters are used throughout the paper. The Ward-identity for the global gauge invariance of the vertex functions is formulated. As an application the Callan-Symanzik equation is derived.
 计算机科学技术学报 , 2009, Abstract: Wireless personal area networks (WPANs) are formed in a relatively small area, and coordinator that serves as a central control device plays an important role in the operation and organization of a piconet. Typical applications of WPANs include home automation systems, security systems and health monitoring systems. In these types of systems, guaranteeing seamless connectivity is very important, and communications cannot take place when the coordinator malfunctions. Thus, in the case of a breakdown, it is necessary to elect a new coordinator as soon as possible. For this reason, a distributed coordinator election scheme (DCES) is proposed that considers not only QoS support but also network connectivity in an effort to avoid possible network partition. Simulation results show that the proposed scheme can elect a new coordinator while maintaining QoS and guaranteeing connectivity for a limited period.
 Computer Science , 2015, Abstract: In two-tiered Wireless Sensor Networks (WSNs) relay node placement is one of the key factors impacting the network energy consumption and the system overhead. In this paper, a novel connectivity-aware approximation algorithm for relay node placement in WSNs is proposed to offer a major step forward in saving system overhead. Specifically, a unique Local Search Approximation Algorithm (LSAA) is introduced to solve the Relay Node Single Cover (RNSC) problem. In this proposed LSAA approach, the sensor nodes are allocated into groups and then a local Set Cover (SC) for each group is achieved by a local search algorithm. The union set of all local SCs constitutes a SC of the RNSC problem. The approximation ratio and the time complexity of the LSAA are analyzed by rigorous proof. Additionally, the LSAA approach has been extended to solve the relay node double cover problem. Then, a Relay Location Selection Algorithm (RLSA) is proposed to utilize the resulting SC from LSAA in combining RLSA with the minimum spanning tree heuristic to build the high-tier connectivity. As the RLSA searches for a nearest location to the sink node for each relay node, the high-tier network built by RLSA becomes denser than that by existing works. As a result, the number of added relay nodes for building the connectivity of the high-tier WSN can be significantly saved. Simulation results clearly demonstrate that the proposed LSAA outperforms the approaches reported in literature and the RLSA-based algorithm can noticeably save relay nodes newly deployed for the high-tier connectivity.
 Mathematics , 2015, Abstract: Caching is a promising solution to satisfy the ever-increasing demands for the multi-media traffics. In caching networks, coded caching is a recently proposed technique that achieves significant performance gains over the uncoded caching schemes. However, to implement the coded caching schemes, each file has to be split into $F$ packets, which usually increases exponentially with the number of users $K$. Thus, designing caching schemes that decrease the order of $F$ is meaningful for practical implementations. In this paper, by reviewing the Ali-Niesen caching scheme, the placement delivery array (PDA) design problem is firstly formulated to characterize the placement issue and the delivery issue with a single array. Moreover, it is disclosed that the problem of designing a centralized coded caching scheme can be translated into a problem of designing an appropriate PDA. Secondly, it is shown that the Ali-Niesen scheme corresponds to a special class of PDA, which realizes the best coding gain with the least $F$. Thirdly, we present a new construction of PDA for the centralized caching system, wherein the cache size of the server is $q$ times of every user's (identical cache size is assumed at all users). The new construction can decrease the required $F$ from the order $O\left(e^{K\cdot\left(\frac{1}{q}\ln q+(1-\frac{1}{q})\ln \frac{q}{q-1}\right)}\right)$ of Ali-Niesen scheme to $O\left(e^{K\cdot\frac{1}{q}\ln q}\right)$, which saves a factor of $O\left(e^{K\cdot(1-\frac{1}{q})\ln\frac{q}{q-1}}\right)$ that increases exponentially with $K$, while the coding gain loss is only $1$.
 Computer Science , 2014, DOI: 10.1117/12.2011660 Abstract: Self-aligned double patterning (SADP) has become a promising technique to push pattern resolution limit to sub-22nm technology node. Although SADP provides good overlay controllability, it encounters many challenges in physical design stages to obtain conflict-free layout decomposition. In this paper, we study the impact on placement by different standard cell layout decomposition strategies. We propose a SADP friendly standard cell configuration which provides pre-coloring results for standard cells. These configurations are brought into the placement stage to help ensure layout decomposability and save the extra effort for solving conflicts in later stages.
 计算机应用 , 2006, Abstract: Sensor deployment is a critical issue in a wireless sensor network.Random diffusion is widely applied to sensor nodes deployment, for example Gauss diffusion and uniform diffusion. The network's coverage and connectivity were discussed on base of random placement. By analyzing full coverage and connectivity, an expression was presented which reflected the relationship among the probability of the full coverage,the range of detection and the number of sensor nodes. Furthermore, the effect of parameters on the probability of full coverage was addressed, compared with the effects of Gauss diffusion and uniform diffusion. In addition, a scheme was proposed to optimize the number of nodes, named "full coverage and radial connectivity". At the end experiment results are given to display our application.
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