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Electronic commerce (e-commerce) is a promising and continuously changing field of business management and information technology. The digital cash transfer system is the modern technology used to carry out the financial transactions electronically in banking sectors in a successful way. In this paper an elliptic curve based untraceable off-line electronic cash system is proposed. The popular cryptographic algorithm ECC providing high level security with smaller key size is used in the system. The scheme satisfies the requirements of a digital cash scheme and in particular preserves dual customer detection, anonymity and provides commanding fraud control facilities. ECC is considered to be best suitable for devices with less memory and so that the portability is guaranteed.

This paper gives the cost analysis of a finite capacity single server bulk queueing model with closedown times. The server serves the customers in batches of maximum size ‘b’ with a minimum threshold value ‘a’. Customers arrive according to a Markovian Arrival Process (MAP). On completion of a service, if the queue length is less than ‘a’, then the server performs a closedown work and then leaves for a vacation of random length. When the server returns from vacation and if the queue length is still less than ‘a’ he avails another vacation and so on until the server finds ‘a’ customers waiting in the queue. After the completion of a service, if the number of customers in the queue is greater than a specified value ‘a’ then the server will continue the batch service with general bulk service rule. On the other hand, if the server finds at least ‘a’ customers during closedown period, he immediately starts serving the batch of ‘a’ customers. Using supplementary variable and imbedded Markov chain techn...

Pupil localization is the most significant preprocessing step in recognizing the iris. Iris images are often degraded by low resolution, specular reflections; occlusion by eyelids, contact lenses etc. In this paper, a novel approach, which combines smoothing of iris images and segmenting the pupil, is proposed. First, a fractional derivative mask is used for smoothening the iris images, which acts as a preprocessing step for improving the accuracy of segmentation. Subsequently, the pupil is segmented from the smoothened iris images, using wavelet transform. From the experimental results, it is clearly evident that the proposed method is not only efficient in pupil segmentation, irrespective of its shape but also capable of handling low contrast images or images with noise. Public Iris databases such as CASIA Version 1.0 and UTIRIS database are used for performance evaluation.

Voice over Internet Protocol (VoIP) or Internet telephony has become an evolutionary and promising technology in the area of telecommunications. Lower costs and simpler maintenance are the major reasons of its increasing popularity. However, the network is inherently unreliable and highly challenged when it comes to quality of service (QoS). The VoIP system is primarily a multi-server system which may also face failures. Hence, in order to study the performance of VoIP, it is proposed to develop a multi-server, loss system with general service times, server breakdown and repair together with preemptive priority queuing discipline, for two types of customers: high priority and low priority. The customers are served immediately if the server is available. However, if all servers are busy, then on the arrival of a high priority customer, the service of a low priority customer is preempted. The steady state distribution of such underlying system is obtained together with the performance measures. A numerical illustration of the obtained results is also presented graphically. The results are validated using simulation.

Generally in call centers, voice calls (say Type 1 calls) are given higher priority over e-mails (say Type 2 calls). An arriving Type 1 call has a preemptive priority over a Type 2 call in service, if any, and the preempted Type 2 call enters into a retrial buffer (of finite capacity). Any arriving call not able to get into service immediately will enter into the pool of repeated calls provided the buffer is not full; otherwise, the call is considered lost. The calls in the retrial pool are treated alike (like Type 1) and compete for service after a random amount of time, and can preempt a Type 2 call in service. We assume that the two types of calls arrive according to a Markovian arrival process (MAP) and the services are offered with preemptive priority rule. Under the assumption that the service times are exponentially distributed with possibly different rates, we analyze the model using matrix-analytic methods. Illustrative numerical examples to bring out the qualitative aspects of the model under study are presented.

The steady state behaviour of a single server non-Markovian queue with multiple vacations and controlled optional re-service is analysed. A batch of customers arrive according to Poisson with rate A, whereas the bulk service is rendered by a single server with a minimum batch size of ‘a and maximum of ‘b’. The service times follow a general distribution. At the completion of an essential service, the leaving batch of customers may request for a re-service with probability n. However, the re-service is rendered only when the number of customers waiting in the queue is less than ‘a’. If no request for re-service is made after the completion of an essential service and numbers of customers in the queue is less than ‘a, then the server will avail a vacation of a random length. When the server returns from vacation and if the queue length is still less than ‘a’ he avails another vacation so on until the server finds ‘a’ customers in the queue. After the completion of an essential service and numbers of...

In this paper, a new single authority electronic voting scheme is proposed, based on elliptic curves. According to the proposed scheme, each voter casts the vote as a point on the elliptic curve and the final tally is computed with the assistance of a single trusted authority. The proposed scheme also meets the essential requirements of e-voting system. Ultimately, the proposed voting scheme fortifies the security properties of the electronic voting procedure, since the secrecy of the particularized vote is preserved by Elgamal cryptosystem and Elliptic curve discrete logarithm problem.

A Mx/G/1 Queueing system with two service modes under (a, c, b) policy is considered. A single server Poisson queue with state dependent service is considered for analysis. The service is rendered with different service patterns (different distributions) as singly or in bulk according to the queue length. If the queue length reaches the threshold value ‘a’ then the server does single service and if the queue length reaches the value ‘c’(c > a), then the server selects batch service with variable batch size with a maximum batch size of ‘b’ (b > c). The server starts the service only if number of customers in the queue is at least ‘a’. The Server switches over from single service to batch service or vice-versa only at service initiation epochs depending on the queue length. The probability generating function of the queue size at an arbitrary time epoch is obtained using supplementary variables technique. Some important performance measures are also obtained. Numerical example is presented in order to illustrate the effectiveness of the model.

We consider a single server retrial queue with batch arrivals, two phases of heterogeneous service and a general vacation time under Bernoulli schedule. We carry out steady state system size distribution of number of customers in retrial group, expected number of customers in retrial group and expected waiting time of the customers in the orbit. We discuss its application of the proposed model to the analysis of a communication protocol.

ANALYSIS OF A BULK QUEUE WITH STATE DEPENDENT ARRIVALS AND MULTIPLE VACATIONS

In this paper a M X / G ( a , b )/1 queueing system with multiple vacations, setup time with N -policy and closedown times is considered. On completion of a service, if the queue length is ξ , where ξ a , then the server performs closedown work. Following closedown the server leaves for multiple vacations of random length irrespective of queue length. When the server returns from a vacation and if the queue length is still less than ‘ N ’, he leaves for another vacation and so on, until he finds ‘ N ’ ( N > b ) customers in the queue. That is, if the server finds at least ‘ N ’ customers waiting for service, then he requires a setup time ‘ R ’ to start the service. After the setup he serves a batch of ‘ b ’ customers, where b ⩾ a . Various characteristics of the queueing system and a cost model with the numerical solution for a particular case of the model are presented.

In this paper a M X / G ( a , b )/1 queueing system with N -policy, multiple vacations and setup time is considered. After finishing a service, if the queue length is less than “ a ”, the server leaves for a vacation of random length. When he returns, if the queue length is less than “ N ” ( N ≥ b ), he leaves for another vacation and so on, until he finally finds at least “ N ” customers waiting for service. After a vacation, if he finds more than “ N ” customers in the system, he requires a setup time R to start the service. After the setup time he starts the service with a batch of “ b ” customers. After a service, if the number of waiting customers is ξ ( ξ ≥ a ) then he serves a batch of min( ξ , b ) customers, where b ≥ a . Server vacation models are useful for the systems in which server wants to utilize his idle time for different purposes. Application of vacation models can be found in production systems, designing local area networks and data communication systems. This paper is concentrated on a vacation system with setup times. In practical situations, the setup time corresponds to the preparatory work of the server before starting the service. We derive the system size distribution and expected length of idle and busy period of a M X / G ( a , b )/1 queueing system with N -policy, multiple vacations and setup time. After finishing a service, if the queue length is less than “ a ”, the server leaves for a vacation of random length. When he returns, if the queue length is less than “ N ” ( N ≥ b ), he leaves for another vacation and so on, until he finally finds at least “ N ” customers waiting for service. After a vacation, if he finds more than “ N ” customers in the system, he requires a setup time R to start the service. After the setup time he starts the service with a batch of “ b ” customers. After a service, if the number of waiting customers is ξ ( ξ ≥ a ) then he serves a batch of min( ξ , b ) customers, where b ≥ a . A cost model for the queueing system is discussed. The numerical solution for a particular case of the model is also presented.

This paper is concerned with the analysis of an Mx/G/1 feedback retrial queue with non-persistent customers and multiple vacations with N-policy. If an arriving batch of customers finds the server idle, one of the arriving customers starts its service immediately and the rest joins a retrial group. Otherwise, if an arriving batch of customers on arrival finds the server busy, becomes impatient and leaves the system with probability (1 - α) and with probability α, they enter into the orbit. At a service completion epoch, if the number of customers in the orbit is zero, the server does a secondary job (vacation) repeatedly until the retrial group size reaches N. At the secondary job completion epoch, if the orbit size is at least N, then the server remains in the system to render service for customers from main pool or from retrial group. At a service completion epoch, the leaving customer may either request for another service with probability f or leave the system forever with probability d (where f + d = 1).

A common problem faced during the clinical recording of the Electroencephalogram (EEG) signals are the eye-blinks and movement of the eye balls. Eye blinks cause changes to the electric fields around the eyes, and consequently over the scalp. As a result, EEG recordings are often significantly distorted, and their interpretation becomes problematic. A number of methods have been proposed to overcome this problem. In this paper, a method for removal of ocular artifacts is proposed using ARMA (Auto-Regressive Moving Average) method with wavelets. A comparison is made for the efficiency of the proposed method without using wavelets. Also, the adaptive filtering technique is used to compare with the proposed method.

In this paper two group signature schemes are developed using the Chinese remainder theorem, the first work is based on exponentiation of primitive root of a prime field and the second work is based on elliptic curves. A trusted authority is involved in the schemes for the construction of the group key and individual participant keys. The constructed keys are used as long run keys. The group signature generated by the trusted authority from the partial signatures of the participants. The security of the proposed schemes depends on the NP-hard problems integer factorization, discrete logarithm and elliptic curve discrete logarithm. The signature schemes are illustrated using Mathematica 6.0 and MATLAB 7.0.

This paper presents an adaptive method for removing electroocular (EOG) artifacts in the electroencephalogram (EEG) records. Artifacts in EEG signals are caused by various factors, like line interference, EOG ( electro-oculogram ) and ECG ( electrocardiogram). These noise sources increase the difficulty in analyzing the EEG and obtaining clinical information. For this reason, it is necessary to design specific filters to decrease such artifacts in EEG records. In this paper, we proposed an adaptive filtering method for removing ocular artifacts from EEG recordings using wavelet transform.

In this paper a Public Key Cryptosystem is proposed using the number theoretic transforms (NTT) over a ring of integer modulo a composite number. The key agreement is similar to ElGamal public key algorithm. The security of the system is based on solution of multivariate linear congruence equations and discrete logarithm problem. In the proposed cryptosystem only fixed numbers of multiplications are carried out (constant complexity) and hence the encryption and decryption can be done easily. At the same time, it is very difficult to attack the cryptosystem, since the cipher text is a sequence of integers which are interrelated. The system provides authentication also. Using Mathematica version 5.0 the proposed algorithm is justified with a numerical example., {"references":["Alfred Menezes J, Paul Van Oorchot C, Scott A Vanstone, \"Hand book\nof Applied Cryptography\", CRC Press, 1997.","S. Cabay and T.P.L. Lam, \"Congruence Techniques for the Exact\nSolution of Integer Systems of Linear Equations, ACM Transactions on\nMathematical Software,Vol.3,No.4, pp386-397, December 1977.","W. Diffie and M. Hellman,\"New Directions in Cryptography\", IEEE\nTransactions on Information Theory,vol.IT-22,pp472-492,1976.","Elsayed Mohammed, .E. Emarah and KH. El-Shennawy, \"A Blind\nSignature Scheme based on Elgamal Signature\", Seventeenth National\nRadio Science Conference Feb.22-24, 2000, Minufiya University, Egypt.","Jacques Patarin, \"Hidden Field Equations (HFE) and Isomorphism of\nPolynomials (IP): two new families of Asymmetric Algorithms\",\nEurocrypt-96, Springer Verlag, pp.33-48.","Mukesh Kumar Singh, \"Public Key Cryptography with Matrices\",\nProceedings of the IEEE Workshop on Information Assurance, United\nStates Military Academy pp146-152, June 2004.","H.J. Nussbaumer, \"Fast Fourier Transform and Convolution\nAlgorithms\", second edition, Springer-Verlag Berlin Heidelberg, New\nYork.","Ramesh C. Agarwal and C. Sidney Burrus, \"Number Theoretic\nTransforms to Implement Fast Digital Convolution\", Proceedings\nof the IEEE, vol.63, No.4, April 1975.","Ronald L. Rivest, Adi Shamir and Leonard M. Adleman, \"A Method for\nObtaining Digital Signatures and Public-Key Cryptosystems\",\nCommunications of the ACM, vol21, no2, pp.120-126, Feb 1978.\n[10] Tom M. Apostol, \"Introduction to Analytic Number Theory\", Springer-\nVerlag 1976.\n[11] Taher Elgamal,\"A public Key Cryptosystem and a Signature Scheme\nBased on Discrete Logarithms\", IEEE Transactions on Information\nTheory, vol.IT31, No4, July 1985.\n[12] Vassil S. Dimitrov, Todor V. Cooklev and Borislav Donevsky,\" Number\nTheoretic Transforms Over the Golden Section Quadratic Field\", IEEE\nTransactions on signal Processing, vol.43, No.8, August 1995."]}

This paper analyses a single server batch arrival retrial queue with active breakdowns, two types of repair, a second optional service and multiple vacations with N-policy. The server may breakdown while providing first essential service. When the server fails, it is repaired immediately. On successful completion of first essential service, the customer may opt for second optional service with probability α. At a service completion epoch, without any request for re-service and the orbit size being zero, the server does a secondary job (vacation) repeatedly until the number of customers in the orbit reaches the threshold value N. At a secondary job completion epoch, if the orbit size in at least N, then the server remains in the system to render service for customers from main pool or from retrial group. The steady state queue size distribution of number of customers in the orbit and expected number of customers in the retrial group are obtained. Some particular cases and reliability measures are discussed. Also, some performance measures are obtained. Numerical illustrations are also provided.

In this paper, a bulk queueing system with server’s choice of admitting reservice, multiple vacations and setup time is considered. At a service completion, the leaving batch may request for reservice with probability ʌ and it is not mandatory to accept it; the server admits this request with a probability α. After the reservice or service completion without request for reservice, if the queue length is less than a, the server leaves for a vacation of random length. After this vacation, if the queue length is still less than ‘a’, the server leaves for another vacation, etc., until he finally finds at least ‘a’ customers waiting for service. At a vacation completion epoch, if the server finds at least ‘a’ customers waiting for service, he requires a setup time to start the service. After a setup time or on service completion or on reservice completion, if the server finds at least ‘a’ customers waiting for service say, [ he serves a batch of min (ξ, b) customers, where t ba. The probability generating func...

This paper studies a batch arrival general bulk service retrial queueing model with constant retrial rate. The primary customers arrive in bulk according to Poisson process and they get service under general bulk service rule with minimum of one customer and maximum of ‘b’ customers. If the arriving batch of customers, of size ‘ζ ’, 1≤ζ ≤ b , finds the server free, then all of them get service immediately; while, if the size of the arriving batch is more than ‘b’, then, ‘b’ customers enter the service station and the remaining ζ - b customers join the orbit. However, if an arriving batch of customers finds the server busy, then the entire batch joins the orbit in order to seek service again. The customers in the orbit will try for service one by one with a constant retrial rate ‘v’ when the server is idle. For the proposed model, the probability generating function of the steady-state queue size distribution at an arbitrary time, expected number of customers in the orbit, expected waiting time, expected length of busy period and expected length of busy cycle are obtained. The cost analysis of the queueing system is discussed. The effects of several parameters on the system are analysed numerically.

A M X /G(a, b) /1 queueing system with restricted number of vacations is considered here. After completing a bulk service, if the queue size is less than ‘a’ then the server leaves for a vacation of random length. When he returns from a vacation, if queue length is still less than ‘a’ , he avails another vacation and so on until he completes M number of vacations in successions or he finds at least ‘a’ customers wait for service. After M vacations, if the queue size is less than ‘a’ then the server will remain in the system until he finds ‘a’ customers in the queue. After a vacation or service completion if the server finds at least ‘a’ customers waiting for service then the server serves according to Neut’s bulk service rule. The probability generating function of queue size at an arbitrary time and some important system performance measures are obtained. Cost model is discussed with numerical illustration.

In this paper, a M X / G ( a , b )/1 queueing system with modified M-vacation policy and variant arrival rate is considered. After a service completion, if the number of waiting customers is less than a, then the server avails of multiple vacations till the queue length reaches a or consecutively avail of M number of vacations, whichever occurs first. After completing the Mth vacation, if the queue length is still less than a then the server remains in the system till it reaches a . The server starts the service only if the queue length

This paper analyses a single server batch arrival retrial queue with active breakdowns, two types of repair and second optional service (SOS). The server provides preliminary first essential service (FES) to the primary arriving customers or customers from retrial group. The server is subject to breakdowns. The customer under service during the failure decides, with probability q, to join the orbit (impatient customer) and, with complementary probability 'p', to remain in the server for repair in order to conclude his remaining service (patient customer). It is considered that the repair time of server during the presence of patient customer and the repair time of the server while the customer (impatient customer) joining the orbit due to failure are different. On completion of FES successfully, the customer may opt for SOS with probability α. Reliability of the proposed model is analysed. Some particular cases are also discussed. Other performance measures are also obtained. The effects of several parameters on the system are analysed numerically.

This paper analyses a non-Markovian bulk queueing model with the possibility of overloading and multiple vacations. It is considered that, on the completion of a service, if the queue length ξ is less than 'a', then the server leaves for a secondary job (vacation) of random length. On returning from this job, again if the queue length is still less than 'a', then the server repeats the secondary job until he finally finds, at least 'a' customers. After a service or a vacation completion epoch, if the server finds at least 'a' customers waiting for service, say ξ (a≤ξ

This paper deals with a single server Poisson queue with state dependent service. The service is rendered with different service modes as singly or in bulk according to the queue length. The service starts only if at least one customer is waiting for service. The server switches over from single service to bulk service only at service initiation epoch according to the queue length. If the number of customers waiting for service is ξ (1 ≤ ξ < a), then the server serves one by one. At the service initiation epoch, if the number of waiting customers ξ is at least 'a' (a < b), then the service is rendered according to Neut's general bulk service rule. At the service completion epoch, if there are no customers in the queue, the server avails multiple vacations, until he finds at least one customer in the queue. The Probability Generating Function (PGF) of the queue size and performance measures are obtained. Numerical results are presented in order to illustrate the effectiveness of performance of the state dependent queue.