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61.
One‐way delay variation (OWDV) has become increasingly of interest to researchers as a way to evaluate network state and service quality, especially for real‐time and streaming services such as voice‐over‐Internet‐protocol (VoIP) and video. Many schemes for OWDV measurement require clock synchronization through the global‐positioning system (GPS) or network time protocol. In clock‐synchronized approaches, the accuracy of OWDV measurement depends on the accuracy of the clock synchronization. GPS provides highly accurate clock synchronization. However, the deployment of GPS on legacy network equipment might be slow and costly. This paper proposes a method for measuring OWDV that dispenses with clock synchronization. The clock synchronization problem is mainly caused by clock skew. The proposed approach is based on the measurement of inter‐packet delay and accumulated OWDV. This paper shows the performance of the proposed scheme via simulations and through experiments in a VoIP network. The presented simulation and measurement results indicate that clock skew can be efficiently measured and removed and that OWDV can be measured without requiring clock synchronization. 相似文献
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《Communications in Nonlinear Science & Numerical Simulation》2014,19(9):2974-2982
For some abstract classes of nonlinear non-autonomous systems with variable and state-dependent delays existence, non-existence and multiplicity of periodic solutions are discussed. To illustrate the efficiency of the method, we obtain some well-known results for applied systems as corollaries of our existence theorems. 相似文献
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Linhe Zhu Xiaoyuan Huang Ying Liu Zhengdi Zhang 《Journal of Mathematical Analysis and Applications》2021,493(2):124539
In the new social media era, it is becoming increasingly important to explore the propagation rules for rumors in social networks. This article is concerned with investigating a diffusive susceptible-infected rumor propagation model with a nonlinear propagation function in a spatially heterogeneous environment. We establish the uniform persistence and analyze the asymptotic behavior of the rumor-spreading steady state for the spatially heterogeneous model when one of the diffusion coefficients tends to zero. Moreover, to better reflect the effect of a time delay on the process of rumor propagation, we establish a spatially homogeneous model with a time delay and prove the existence and local stability of the corresponding equilibrium point. Furthermore, the optimal control in the spatially homogeneous environment case is derived. Finally, several numerical simulations are performed to verify the theoretical results in both spatially heterogeneous and spatially homogeneous systems. 相似文献
67.
The Substitution box (S-Box) forms the core building block of any hardware implementation of the Advanced Encryption Standard (AES) algorithm as it is a non-linear structure requiring multiplicative inversion. This paper presents a full custom CMOS design of S-Box/Inversion S-Box (Inv S-Box) with low power GF (28) Galois Field inversions based on polynomial basis, using composite field arithmetic. The S-Box/Inv S-Box utilizes a novel low power 2-input XOR gate with only six devices to achieve a compact module implemented in 65 nm IBM CMOS technology. The area of the core circuit is only about 288 μm2 as a result of this transistor level optimization. The hardware cost of the S-Box/Inv S-Box is about 158 logic gates equivalent to 948 transistors with a critical path propagation delay of 7.322 ns enabling a throughput of 130 Mega-SubBytes per second. This design indicates a power dissipation of only around 0.09 μW using a 0.8 V supply voltage, and, is suitable for applications such as RFID tags and smart cards which require low power consumption with a small silicon die. The proposed implementation compares favorably with other existing S-Box designs. 相似文献
68.
In this article we propose a stage-structured predator–prey model with disturbing pulse and time delays and obtain the sufficient conditions for the global attractivity of predator-eradiation periodic solution and permanence of the system. We also show that time delay, pulse catching rate and the period of pulsing can affect the dynamics of the system. 相似文献
69.
Michael Thompson 《Trends in analytical chemistry : TRAC》2011,30(7):1168
Analytical chemists can advantageously use an uncertainty function to describe the performance of an analytical system in terms of the standard uncertainty or standard deviation as a function of the concentration of the analyte. This “characteristic function” is useful for estimating uncertainty at a new concentration. A similar function can be used to prescribe the uncertainty that is regarded as fit for purpose for a particular application. This “fitness function” is useful in setting standards of accuracy in proficiency tests and similar exercises without revealing the concentration of the analyte. In combination, these two functions provide a rational basis for method selection. 相似文献
70.
The allocation of cost savings is very important for the success of the joint relationship between the buyer and vendor in supply chain management. This paper develops integrated models with permissible delay in payments for determining the optimal replenishment time interval and replenishment frequency. In addition, the variant pricing strategy is employed to obtain both sides’ cost savings in order to entice buyers to join long-term cooperative relationships. A simple solution algorithm is presented to allocate the cost savings in the integration model, and a numerical example is used to demonstrate the feasibility of the proposed integration models. 相似文献