Stream Scheme Research Articles

Stream Privacy Amplification for Quantum Cryptography

Privacy amplification is the key step to guarantee the security of quantum communication. The existing security proofs require accumulating a large number of raw key bits for privacy amplification. This is similar to block ciphers in classical cryptography that would delay the final key generation since an entire block must be accumulated before privacy amplification. Moreover, any leftover errors after information reconciliation would corrupt the entire block. By modifying the security proof based on quantum error correction, we develop a stream privacy amplification scheme, which resembles the classical stream cipher. This scheme can output the final key in a stream way, prevent error from spreading, and hence can put privacy amplification before information reconciliation. The stream scheme can also help to enhance the security of trusted-relay quantum networks. Inspired by the connection between stream ciphers and quantum error correction in our security analysis, we further develop a generic information-theoretic tool to study the security of classical encryption algorithms.

Time-Accurate Flow Simulations Using a Finite-Volume Based Lattice Boltzmann Flow Solver with Dual Time Stepping Scheme

In this study, the Lattice Boltzmann Method (LBM) is implemented through a finite-volume approach to perform 2D, incompressible, and time-accurate fluid flow analyses on structured grids. Compared to the standard LBM (the so-called stream and collide scheme), the finite-volume approach followed in this study necessitates more computational effort, but the major limitations of the former on grid uniformity and Courant–Friedrichs–Lewy (CFL) number that is to be one are removed. Even though these improvements pave the way for the possibility of solving more practical fluid flow problems with the LBM, time-accurate simulations are still restricted due to the stability criteria dictated by high-aspect ratio grid cells that are usually required for adequate resolution of boundary layers and the stiffness due to the nature of the equation that are being solved. To overcome this limitation, a Dual Time Stepping (DTS) scheme, which iterates the solution in pseudo time using an Implicit-Explicit (IMEX) Runge–Kutta method while advancing the solution in physical time with an explicit scheme (backward difference formula), is developed and implemented. The accuracy of the resulting flow solver is evaluated using benchmark flow problems and overall second-order accuracy is demonstrated.

A Chaos Robustness Criterion for 2D Piecewise Smooth Map with Applications in Pseudorandom Number Generator and Image Encryption with Avalanche Effect

This study proposes a chaos robustness criterion for a kind of 2D piecewise smooth maps (2DPSMs). Using the chaos robustness criterion, one can easily determine the robust chaos parameter regions for some 2DPSMs. Combining 2DPSM with a generalized synchronization (GS) theorem, this study introduces a novel 6-dimensional discrete GS chaotic system. Based on the system, a 216-word chaotic pseudorandom number generator (CPRNG) is designed. The key space of the CPRNG is larger than 2996. Using the FIPS 140-2 test suit/generalized FIPS 140-2 test suit tests the randomness of the 1000 key streams consists of 20,000 bits generated by the CPRNG, the RC4 algorithm, and the ZUC algorithm, respectively. The numerical results show that the three algorithms do not have significant differences. The CPRNG and a stream encryption scheme with avalanche effect (SESAE) are used to encrypt an image. The results demonstrate that the CPRNG is able to generate the avalanche effects which are similar to those generated via ideal CPRNGs. The SESAE with one-time-pad scheme makes any attackers have to use brute attacks to break our cryptographic system.

Meritocracy in the Civil Service – Young Professionals Scheme – in Romania

In 2003 a joint program, “Young Professional Scheme”(YPS), developed by the Romanian Government and the European Commission was initiated in order to create a corps of professional civil servants, called public managers. As initially presented the scheme supposed to have been inspired and decisively influenced by the UK's Fast Stream Scheme. The idea of the programme was to have an input of good educational practices in Romania and also a selection process based on skills, abilities, learning capacity and will to change. It initial purpose was to create a Fast track scheme giving the participants the opportunity to have a career based on merit, out of the usual constraints and outlived procedures of the public administration. This paper intent to present an objective analysis of the Young Professional Scheme related to the Fast Stream Programme.

Fast H.264/AVC stream joiner for interactive free view-area multivision video

With the spread of high-definition video devices, and with the advance of digital broadcasting systems and video portal services in the Internet domains, numerous high-definition video presentations become available in everyday life. Under these circumstances, the desire of people to enjoy video contents in new ways had grown. This paper proposes a new multivision video provisioning system that enables numerous users to access any view area with any desired resolution interactively. The basic idea is that the partial area (tile)-based pre-coded video streams are stored in advance. These multiple streams are joined dynamically and delivered based on the user's view-area position. In this paper, the details of H.264/AVC tile-based video coding and a fast tile stream joiner scheme are presented. Simulation experiments and our practical implementation demonstrate the feasibility and effectiveness of our proposal.

The stream volume of fluid advection algorithm

The Volume of Fluid (VOF) method is a powerful tool for modelling the movement of free surface fluid flows. In this paper, a new VOF advection algorithm is presented, termed the Stream scheme. The algorithm uses a linear piecewise method for free surface reconstruction, coupled to a unique fully multidimensional method of cell boundary flux integration. Comparisons with other VOF advection algorithms show the performance of the new scheme to be good.

A robust scheme for distributed speech recognition over loss-prone packet channels

In this paper, we propose a whole recovery scheme designed to improve robustness against packet losses in distributed speech recognition systems. This scheme integrates two sender-driven techniques, namely, media-specific forward error correction (FEC) and frame interleaving, along with a receiver-based error concealment (EC) technique, the weighted Viterbi algorithm (WVA). Although these techniques have been already tested separately, providing a significant increase of performance in clean acoustic environments, in this paper they are jointly applied and their performance in adverse acoustic conditions is evaluated. In particular, a noisy speech database and the ETSI Advanced Front-end are used, while the dynamic features, which play an important role in adverse acoustic environments, and their confidences for the WVA algorithm are examined. In order to solve the issue of mixing two sender-driven techniques (both causing a delay) whose direct composition causes an increase of the global latency, we propose a double stream scheme which limits the latency to the maximum delay of both techniques. As a result, with very few overhead bits and a very limited delay, the integrated scheme achieves a significant improvement in the performance of a DSR system over a degraded transmission channel, both in clean and noisy acoustic conditions.

Adaptive MIMO-MLSE Blind Detection in Heterogeneous Stream Transmission for Mobile Radio Communications

This paper proposes a novel MIMO system that introduces a heterogeneous stream (HTS) scheme and a blind signal detection method for mobile radio communications. The HTS scheme utilizes different modulation or coding methods for different MIMO streams, and the blind detection method requires no training sequences for signal separation, detection, and channel estimation. The HTS scheme can remove the ambiguity in identifying separated streams without unique words that are necessary in conventional MIMO blind detection. More specifically, two examples of HTS are considered: modulation type HTS (MHTS) and timing-offset type HTS (THTS). MHTS, which utilizes different modulation constellations with the same bandwidth for different streams, has been previously investigated. This paper proposes THTS which utilizes different transmission timing with the same modulation. THTS can make the blind detection more robust and effective with fractional sampling. The blind joint processing of detection and channel estimation performs adaptive blind MIMO-MLSE and is derived from an adaptive blind MLSE equalizer that employs the recursive channel estimation with the Moore-Penrose generalized inverse. Computer simulations show that the proposed system can achieve superior BER performance with Eb/N0 degradation of 1dB in THTS and 2.5dB in MHTS compared with the ideal maximum likelihood detection.

A New Volume of Fluid Advection Algorithm: The Stream Scheme

A new VOF advection algorithm is presented, termed the Stream scheme. The algorithm uses a linear piecewise method for free surface reconstruction, coupled to a unique fully multidimensional method of cell boundary flux integration. The performance of the new algorithm is compared against other VOF advection algorithms using a variety of standard advection tests. In general, the performance of the Stream scheme appears superior to existing multidimensional and dimensionally split advection algorithms.

Development of a Parallelism Analysis Integrated System for a Fast-Running Pressurized Water Reactor Plant Predictive Simulator

This paper reports on a parallelism analysis integrated system (PARIS) with a multiple instruction stream-multiple data stream (MIMD) scheme developed to analyze simulation programs and generate a parallel execution program for parallel processing. This simulation program can predict effects of anomalies in nuclear plants. The PARIS system first analyzes task parallelism and the processing time of each task after a user divides a program developed for a single processor into many elementary assignment units. The system then assigns tasks to processors using the critical path/most immediate successor first scheduling algorithm to minimize the overall processing time, and it generates the parallel execution program, which can be executed with a tightly coupled multiprocessor. The PARIS system has two scheduling methods so it can assign tasks to the multiprocessor both before and during execution of the program.