In this study, the path planning problem in 3D automated optical inspection (AOI) machines is considered. In the problem, the primary objective is finding a path that minimizes the total working time among all possibl...
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In this study, the path planning problem in 3D automated optical inspection (AOI) machines is considered. In the problem, the primary objective is finding a path that minimizes the total working time among all possible paths for the camera. In 3D AOI machines, a very precise level of image processing has to be performed when inspecting the mounted components on printed circuit boards (PCBs). Therefore, both the routing time of the camera path and the image processing time have to be considered when calculating the total working time of the camera in the AOI machines. In this paper, we propose efficient heuristic algorithms that can find the paths that have the shortest total working times. The performances of the proposed methods primarily depend on the NEH-based procedure, which is one of our proposed improvement procedures. We introduce several construction and improvement procedures, and select the best combination as our proposed approach. The results of computational experiments conducted on real data to evaluate the performance of our proposed approach show that our proposed methods improve on the original path planning performances. In addition, tests done on randomly generated data indicate that our proposed approach is superior to other benchmark approaches, including metaheuristic algorithms, in terms of computing time and performance measures.
An L(2,1)-labeling of a graph G is an assignment f from the vertex set V(G) to the set of nonnegative integers such that vertical bar f (x) - f (y)vertical bar >= 2 if x and p are adjacent and vertical bar f (x) - ...
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ISBN:
(纸本)9783642175626
An L(2,1)-labeling of a graph G is an assignment f from the vertex set V(G) to the set of nonnegative integers such that vertical bar f (x) - f (y)vertical bar >= 2 if x and p are adjacent and vertical bar f (x) - f(y)vertical bar >= 1 if x and y are at distance two for all x and y in V(G). The span of an L(2,1)-labeling f is the maximum value of f (x) over all vertices x of G. The L(2,1)-labeling number of a graph G, denoted as lambda(G), is the least integer k such that G has an L(2,1)-labeling with span k. Since the decision version of the L(2,1)-labeling problem is NP-complete, it is important to investigate heuristic approaches. In this paper, we first implement some heuristic algorithms and then perform an analysis of the obtained results.
Subcarrier-and-bit allocation has been extensively investigated in the literature to improve spectral efficiency of multiuser OFDM systems. However, in previous studies, nearly all the studies are focused on single-cl...
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ISBN:
(纸本)9780780393912
Subcarrier-and-bit allocation has been extensively investigated in the literature to improve spectral efficiency of multiuser OFDM systems. However, in previous studies, nearly all the studies are focused on single-class service. In this paper, formulation of adaptive subcarrier-and-bit allocation for multiclass multiuser OFDM system is presented. The objective is to maximize the instantaneous total system revenue with the quality-of-service (QoS) of each class guaranteed. Since complexity to the exact solution is generally high and involves solving of nonlinear objective function and constraints, two suboptimal approaches to this problem are presented. The first approach uses a quadratic approximation to the objective function;while in the second approach, a two-step algorithm is developed to obtain the suboptimal solution. The solution is first relaxed to real numbers with some constraints removed before the integer solutions are obtained. The accuracy and complexity of these two approaches are compared with each other as well as with the optimal solution.
In the paper, we consider a special situation of minimizing the total earliness and tardiness for the single-machine multi-criteria scheduling problem, in where the cost of earliness and tardiness penalty penalties ar...
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ISBN:
(纸本)9783642340406
In the paper, we consider a special situation of minimizing the total earliness and tardiness for the single-machine multi-criteria scheduling problem, in where the cost of earliness and tardiness penalty penalties are equal to each other and take 1. We propose some properties for the optimal schedule and present the heuristic algorithms for solving this problem, and then, we analyze its quality by an example.
In recent years, meta-heuristic optimization algorithms have been increasingly studied due to their wide applicability in practical applications. However, the interference of redundant dimensions in complex high-dimen...
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Connected dominating set (CDS) is widely used in wireless networks as a virtual backbone for communication and routing between nodes. In order to measure the quality of a CDS, most researches in this area focus on red...
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ISBN:
(纸本)9783642146534
Connected dominating set (CDS) is widely used in wireless networks as a virtual backbone for communication and routing between nodes. In order to measure the quality of a CDS, most researches in this area focus on reducing the size of a CDS, neglecting other important metrics, such as diameter between two communication parties. This paper considers the diameter as a quality factor for CDS construction, and develops two new heuristic algorithms. In particular, the CDS computed by the first algorithm has constant ratios 9 and 3 for its size and diameter, respectively. And that of the second algorithm has constant ratios 5 + In 10 and 2. Both theoretical analysis and simulation show out the performance of the algorithms.
This paper presents two novel heuristic algorithms for the design of wireless access multimedia networks. Emphasis was given to the design of CDMA based wireless multimedia networks and Fixed Wireless multimedia netwo...
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ISBN:
(纸本)0769525946
This paper presents two novel heuristic algorithms for the design of wireless access multimedia networks. Emphasis was given to the design of CDMA based wireless multimedia networks and Fixed Wireless multimedia networks. The objectives of these methods are first to place a number of access points/base stations in a number of candidate sites and then to assign a number of fixed wireless terminals to the selected access points/base stations. Both methods are based on Graph Theory and they are essentially greedy algorithms. Except from capacity constraints, wireless reception characteristics are also considered. The algorithms are capable of designing medium and large-scale networks at polynomial time. Both algorithms were compared with an analogous optimisation problem through a series of tests. The results indicate that as regards design costs the performance of the heuristics is very close to this of the equivalent optimisation problem. The solution times for the heuristics are smaller especially when the number of the candidate access points/base stations becomes large.
In this paper we consider a modified three dimensional bin packing problem which appears in loading vehicles during planning transportation. This model is a common generalization of two multidimensional bin packing mo...
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ISBN:
(纸本)9781467345194
In this paper we consider a modified three dimensional bin packing problem which appears in loading vehicles during planning transportation. This model is a common generalization of two multidimensional bin packing models (box packing and vector packing). We analyse two simple heuristic algorithms for the solution of the problem and their extension with the interval preparation method. We test these algorithms by experiments on test data derived from the literature and show that in some test classes using the extension we can obtain better solutions, and the time requirement does not grow tremendously.
To allocate Audio Conference Servers (CS) [1] for virtual conferencing over JP, we leverage Session Initiation Protocol (SIP) for signaling. We address here the problem of facilitating seamless conference amongst part...
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ISBN:
(纸本)0769523730
To allocate Audio Conference Servers (CS) [1] for virtual conferencing over JP, we leverage Session Initiation Protocol (SIP) for signaling. We address here the problem of facilitating seamless conference amongst participants using CSs. This demands a proper allocation of CSs to clients to maximize the number of participants served and at a reduced cost. Seeking a more realistic approach, we avoid oversimplifying assumptions;hence the problem becomes relatively harder. We present three heuristic algorithms for these NP-hard problems and bring about the effectiveness of their performance.
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