A self-learning approach for proactive resource and service provisioning in fog environment

The Journal of Supercomputing - With increasing growth in IoT, the number of devices connected to the Internet is constantly growing. Moreover, the increase in the volume of data and their...     

An all-solid-state broad-band frequency multiplier chain at 1500 GHz

We report the results of a high-performance all-solid-state broad-band frequency multiplier chain at 1500 GHz, which uses four cascaded planar Schottky-barrier varactor doublers. The multipliers are driven by monolithic-microwave integrated-circuit-based high electron-mobility transistor power amplifiers around 95 GHz with 100-150 mW of pump power. The design incorporates balanced doublers utilizing novel substrateless and membrane device fabrication technologies, achieving low-loss broad-band multipliers working in the terahertz range. For a drive power of approximately 100 mW in the 88-99-GHz range, the doublers achieved room-temperature peak efficiencies of approximately 30% at the 190-GHz stage, 20% at 375 GHz, 9% at 750 GHz, and 4% at the 1500-GHz stage. When the chain was cooled to 120 K, approximately 40 /spl mu/W of peak output power was measured for 100 mW of input pump power.     

Probabilistic analysis of a two-unit cold standby redundant system subject to failure of controlled weather device

This paper studies stochastic analysis of a two-unit cold standby system taking into account failure of a weather condition device. All failure times and time to repair the weather condition device have a negative exponential distribution, whereas repair rates of the operating unit are general. The regenerative points technique in Markov renewal processes (MRP) is applied to obtain several reliability characteristics of interest to system designers.     

A hardware oriented fuzzification algorithm and its VLSI implementation

An efficient fuzzification algorithm named as Dynamic Precision Fuzzification (DPF) is introduced in this paper which is mainly developed for hardware implementation. The DPF which might be generally used with any piecewise linear membership function, exploits an inherent capacity of the normal fuzzification algorithm to improve its efficiency when realized in a finite-precision implementation bed such as digital VLSI. The accuracy simulation results of the DPF and normal fuzzification method are presented and compared to show the superiority of the DPF. As the word-length is the most important parameter in a finite-precision implementation environment which determines the system cost-precision trade-off, the simulation results show that DPF provides suitable precision improvements with respect to traditional fuzzification without increasing the system word-length. The VLSI synthesis results of both methods are also presented to show that this considerable accuracy improvement is achieved by an acceptable increase in its VLSI implementation costs in terms of area, delay, and power consumption with respect to traditional methods.     

QoS and preemption aware scheduling in federated and virtualized Grid computing environments

Resource provisioning is one of the challenges in federated Grid environments. In these environments each Grid serves requests from external users along with local users. Recently, this resource provisioning is performed in the form of Virtual Machines (VMs). The problem arises when there are insufficient resources for local users to be served. The problem gets complicated further when external requests have different QoS requirements. Serving local users could be solved by preempting VMs from external users which impose overheads on the system. Therefore, the question is how the number of VM preemptions in a Grid can be minimized. Additionally, how we can decrease the likelihood of preemption for requests with more QoS requirements. We propose a scheduling policy in InterGrid, as a federated Grid, which reduces the number of VM preemptions and dispatches external requests in a way that fewer requests with QoS constraints get affected by preemption. Extensive simulation results indicate that the number of VM preemptions is decreased at least by 60%, particularly, for requests with more QoS requirements.     

Predictor Feedback Stabilization of Stochastic Linear Delayed Systems with Both Additive and Multiplicative Noises

In this paper we investigate memory control of stochastic linear delayed systems with both additive and multiplicative noises. A new formula is first presented to obtain the prediction vector from the system dynamics and then it is used for feedback to reduce the input delay in the original delayed system. To ensure the stability of closed‐loop system, some matrix inequality conditions are given that in the case of feasibility provide the stabilizing gain of the predictor controller. The proposed method is applied to stochastic quarter‐car model of an active suspension system to show the effectiveness of the approach.     

Reliability of a reparable system with preventive maintenance and imperfect switch

A two-unit cold standby redundant system with repair, post-repair, preventive maintenance (PM) and imperfect switchover is considered using three types of PM [types (a), (b) and (c)]. The Laplace transform (LT) of the survivor function (sf) of time to the first system failure (TFSF) and the mean TFSF are derived. A theorem about the effect of PM [type (a)] is proved. Finally numerical calculations are presented to illustrate the results.