Chengming Qi

An Improved Ant Colony Algorithm for VRPTW

The vehicle routing problem with time windows (VRPTW) is a well-known and complex combinatorial problem. The primary objective of VRPTW is defined as the minimization of the number of routes or vehicles. Minimization of the total travel cost is secondary objective. This paper proposes an improved algorithm based on the ant colony system (ACS), which hybridized with randomized algorithm (RACS-VRPTW). In two objectives of VRPTW, only partial customers are randomly chosen to compute the transition probability. Experiments on various aspects of the algorithm and computational results for partial benchmark problems are reported. We compare our approach with some other meta-heuristics and show that our results are competitive.

Using Ant Colony System and Local Search Methods to Solve VRPTW

The vehicle routing problem with Time windows (VRPTW) issue has attracted significant attention in the operations research community in recent years. The primary objective of VRPTW is defined as the minimization of the number of routes or vehicles. Minimization of the total travel cost is secondary objective. In this paper, VRPTW is examined and a hybrid ant colony system coupled with randomized algorithm (RA) and Pareto local search (PLS) algorithm (RPACS-VRPTW), is proposed. The RPACS-VRPTW can efficiently reduce costs of the constructive procedure of the solution in the ant colony system (ACS). Computational results for partial benchmark problems show that the approach proposed outperforms some other previously known heuristic methods.

An improved group signatures scheme based on discrete logarithm problem

A group signature scheme allows a group member to sign a message anonymously on behalf of the group. In case of a dispute, the group manager can reveal the actual identity of signer. In this paper, we propose an efficient group signature scheme, which divide the document M into m blocks and add some redundant bits to each message block, to avoid the conspiracy attack. The security of the proposed scheme is based on the difficulty of computing the discrete logarithm modulo for a composite number. The size of the group signature and the verification time of the group signature are equivalent to that of an individual signature.

A new threshold signature scheme based on ECC and factoring

Most of the existing digital signature schemes were developed based on a single hard problem like factoring, discrete logarithm or elliptic curve discrete logarithm problems. In this paper, we proposed a new threshold signature scheme based on multiple hard problems namely factoring and elliptic curve discrete logarithm problems. We combined the two problems into both signing and verifying equations. The new scheme was shown to be secure against the known attacks for signature schemes. The efficiency performance of our scheme is given. Our scheme provides longer and higher security level than that scheme based on one problem.

Hybrid ant colony algorithm for QAP

Ant colony algorithm (ACA), inspired by the food-searching behavior of ants, is an evolutionary algorithm and performs well in discrete optimization. In this paper, through an analysis of the constructive procedure of the solution in the ACA, a hybrid ant colony system(PLSACA) with Pareto Local Search(PLS), is proposed. In PLSACA, only partial facilities are randomly chosen to compute the designed probability and some of the solutions are intensified using local search. Computational results demonstrate that our algorithm generates competitive results compared to the best known solutions of the test instances.

A New Formal Concept Analysis Method and Its Construction Algorithm

For solving the redundancy of nodes and edges in concept lattice, we replace lattice with join-semilattice and present an algorithm which relies upon a strategy of gradual insertion of the concepts into the partially built hasse diagram. A threshold value is introduced to limit the number of concept nodes. We present the implementation of this algorithm and demonstrate the process of concept semilattice updating by an example. Experimental results show its effectiveness and efficiency.

A Two-Stage Hybrid Ant Colony Algorithm for the CVRP

Capacitated vehicle routing problem(CVRP) is an important combinatorial optimization problem which has received considerable attention in the last decades. The Ant Colony system (ACS) is a metaheuristic which is inspired by the trail following behavior of real ant colonies. This paper proposes a two-stage hybrid ACS algorithm for CVRP. The algorithm first minimizes the number of vehicles using ACS and then minimizes travel cost using iterated local search(ILS). In first stage, we revised the ACS algorithm with randomized algorithm(RA) to compute the transition probability. Experimental results for partial benchmark problems demonstrate the effectiveness of the algorithm.

Learning classification rules based on concept semilattice

Concept lattice is an efficient formal tool for data analysis and knowledge extraction. In this paper, we present an incremental construction algorithm of join-semilattice with a simple example and a novel induction algorithm, Rulextracter, which induces classification rules using a semilattice as an explicit map through the search space of rules. Furthermore, our learning system is shown to be robust in the presence of noisy data. The Rulextracter system is also capable of learning both decision lists as well as unordered rule sets and thus allows for comparisons of these different learning paradigms within the same algorithmic framework.

A New Digital Proxy Signature Scheme Based on ECDLP

In the proxy signature scheme the proxy signer has the power to act on behalf of the original signer. In order to overcome the security threats and weaknesses in existing schemes, a new proxy signature based on elliptic curve cryptosystem (ECC) is presented. The scheme renders effective protection for the secrecy of proxy signers with probabilistic encryption algorithm. The one-way hash function based on elliptic curves discrete logarithm problem (ECDLP) is used, which has a low computational cost and small key size. The security analysis shows that the proposed scheme has the ability to control the scope of delegation reliably, resist the known attacks and prevent the abuse of proxy digital signature power. It has higher working efficiency, less operation expense, stronger security and better in reliability.

Concept Semilattice: Construction and Complexity

Concept lattice is widely used in data analysis. This paper aims to reduce redundant nodes from concept lattice by replacing lattice with join-semilattice. We develop an algorithm based on gradual insertion of concepts into partially hasse diagram. An example is proposed to illustrate the constructing procedure of concept semilattice. Experimental results show effectiveness and efficiency of the proposed algorithm.