Uniform processing of V-shaped and tri-planar graphite/epoxy composite parts has been achieved in a single mode cavity using variable frequency microwave energy. A computer process control system was used to achieve u...
详细信息
Uniform processing of V-shaped and tri-planar graphite/epoxy composite parts has been achieved in a single mode cavity using variable frequency microwave energy. A computer process control system was used to achieve uniform heating and stable curing temperature. The control parameters were microwave frequency and power. The control algorithm was mainly composed of two parts: intelligent mode selection for uniform heating, and power control for constant curing temperature. Experimental results were compared between single mode heating, mode sweeping heating, and intelligent mode switching heating. The comparison showed significant improvement of temperature uniformity using the intelligent mode switching technique.
computer algorithms and graphical solutions for deflection-based closed-form back-calculation of rigid pavement properties are available. However, a solution in the form of regression equations would have useful pract...
详细信息
computer algorithms and graphical solutions for deflection-based closed-form back-calculation of rigid pavement properties are available. However, a solution in the form of regression equations would have useful practical applications because of the speed and convenience in computation. This work presents a regression model for this purpose based on the closed-form back-calculation algorithm NUS-BACK. The input parameters remain the same as the original closed-form algorithm, with no requirements for seed values or initial guess of pavement properties. The database for the development of the regression model was established by forward computation of deflections for practical ranges of pavement properties. The verification of the regression model is presented by checking against the solutions of the closed-form algorithm NUS-BACK. The reliability of the regression equations was assessed against the closed-form algorithm for two conditions of input deflections: one for exact deflection measurements with no errors, another for deflection measurements with random errors. The analysis showed that the regression model could provide comparable reliability and accuracy to the analytical closed-form solution by NUS-BACK.
We have developed an improved algorithm that allows us to enumerate the number of site animals on the square lattice LIP to size 46. We also calculate the number of lattice trees up to size 44 and the radius of gyrati...
详细信息
We have developed an improved algorithm that allows us to enumerate the number of site animals on the square lattice LIP to size 46. We also calculate the number of lattice trees up to size 44 and the radius of gyration of both lattice animals and trees up to size 42. Analysis of the resulting series yields an improved estimate, lambda =4.062570(8), for the growth constant of lattice animals, and, lambda (0)=3.795254(8), for the growth constant of trees, and confirms to a very high degree of certainty that both the animal and tree generating Functions have a logarithmic divergence. Analysis of the radius of gyration series yields the estimate, nu =0.64115(5), for the size exponent.
In this paper, we present, formalize and prove the correctness of recovery algorithm for our open and safe nested transaction model using I/O automaton model. Our nested transaction model uses the notion of a recovery...
详细信息
In this paper, we present, formalize and prove the correctness of recovery algorithm for our open and safe nested transaction model using I/O automaton model. Our nested transaction model uses the notion of a recovery point subtransaction in the nested transaction tree. It introduces a prewrite operation before each write operation to increase the potential concurrency. Our transaction model is termed as "open and safe" as prewrites allow early reads (before database writes on disk) without cascading aborts. The systems restart and buffer management operations are modelled as nested transactions to exploit possible concurrency during restart. Each non-access transaction, object, and the scheduler is modeled as I/O automaton. Each of these automata is specified with the help of some pre-and post-conditions. These pre- and post-conditions capture the operational semantics and the behavior of each automaton during recovery operations. Our proof technique makes use of assertional reasoning and provide many interesting invariant, thus gives a better understanding of our recovery algorithm.
The adaptive control system with reference models of local subsystems was considered. The proposed control algorithms were proved to provide zero errors of following the local reference models under a priori uncertain...
详细信息
The adaptive control system with reference models of local subsystems was considered. The proposed control algorithms were proved to provide zero errors of following the local reference models under a priori uncertainty of the parameters and interrelations of the subsystems. In doing so, only the measurable variables of the local subsystems were used to generate the control actions and in the adjustment algorithms, that is, control was totally decentralized.
We have developed a transfer matrix algorithm for the enumeration of compact self-avoiding walks on rectangular strips of the square lattice. The algorithm is easily adapted to other shapes or generalized to problems ...
详细信息
We have developed a transfer matrix algorithm for the enumeration of compact self-avoiding walks on rectangular strips of the square lattice. The algorithm is easily adapted to other shapes or generalized to problems such as interacting walks. These models are relevant in the study of globular proteins. (C) 2001 Elsevier Science B.V. All rights reserved.
We have developed a transfer matrix algorithm for the enumeration of compact self-avoiding walks on rectangular strips of the square lattice. The algorithm is easily adapted to other shapes or generalized to problems ...
详细信息
We have developed a transfer matrix algorithm for the enumeration of compact self-avoiding walks on rectangular strips of the square lattice. The algorithm is easily adapted to other shapes or generalized to problems such as interacting walks. These models are relevant in the study of globular proteins. (C) 2001 Elsevier Science B.V. All rights reserved.
In this paper we will describe our recent results related to the design of hybrid on-line Failure Detection and Identification (FDI) and Adaptive Reconfigurable Control (ARC) algorithms for aerial and space vehicles. ...
详细信息
ISBN:
(纸本)0780367332
In this paper we will describe our recent results related to the design of hybrid on-line Failure Detection and Identification (FDI) and Adaptive Reconfigurable Control (ARC) algorithms for aerial and space vehicles. Our approach is based on the Multiple Models, Switching and Tuning (MMST) methodology and its extensions, and has been demonstrated as an efficient tool for hybrid fault tolerant control under subsystem and component failures and structural damage.
Partially Observable Markov Decision Process (POMDP) is a general sequential decision-making model where the effects of actions are nondeterministic and only partial information about world states is available. Howeve...
详细信息
Partially Observable Markov Decision Process (POMDP) is a general sequential decision-making model where the effects of actions are nondeterministic and only partial information about world states is available. However, finding near optimal solutions for POMDPs is computationally difficult. Value iteration is a standard algorithm for solving POMDPs. It conducts a sequence of dynamic programming (DP) updates to improve value functions. Value iteration is inefficient for two reasons. First, a DP update is expensive due to the need of accounting for all belief states in a continuous belief space. Second, value iteration needs to conduct a large number of DP updates before its convergence. This thesis investigates two ways to accelerate value iteration. The work presented centers around the idea of conducting DP updates and therefore value iteration over a belief subspace, a subset of belief space. The first use of belief subspace is to reduce the number of DP updates for value iteration to converge. We design a computationally cheap procedure considering a belief subspace which consists of a finite number of belief states. It is used as an additional step for improving value functions. Due to additional improvements by the procedure, value iteration conducts fewer DP updates and therefore is more efficient. The second use of belief subspace is to reduce the complexity of DP updates. We establish a framework on how to carry out value iteration over a belief subspace determined by a POMDP model. Whether the belief subspace is smaller than the belief space is model dependent. If this is true for a POMDP, value iteration over the belief subspace is expected to be more efficient. Based on this framework, we study three POMDP classes with special problem characteristics and propose different value iteration algorithms for them. (1) An informative POMDP assumes that an agent always has a good idea about the world states. The subspace determined by the model is much smaller th
The throughput results for file transfers using file sizes ranging from 1 Kbytes through 1 Mbytes using both the standard TCP/IP and SCPS protocol stacks over a PPP link are reported. Channel properties were simulated...
详细信息
ISBN:
(纸本)0780365992
The throughput results for file transfers using file sizes ranging from 1 Kbytes through 1 Mbytes using both the standard TCP/IP and SCPS protocol stacks over a PPP link are reported. Channel properties were simulated using a space channel simulator with a range of balanced and unbalanced link speeds and channel error rates. The throughput results will show the effects of link configuration and channel error rate on file transfer time. The host computer configuration options for the protocols are factored into the comparison. The throughput reporting shows the effects of header compression and selection of congestion algorithm upon the results. The TCP/IP ftp and SCPS-FP using VJ congestion control algorithm results give similar results and better results than SCPS-FP with the Vegas congestion control algorithm in these experiments. No noticeable delay effects were noted with links delays corresponding to GEO orbits with file transfers of 1 Mbytes.
暂无评论