Search results for "Scheduling"
showing 10 items of 275 documents
Enabling a win-win coexistence mechanism for WiFi and LTE in unlicensed bands
2018
The problem of WiFi and LTE coexistence has been significantly debated in the last years, with the emergence of LTE extensions enabling the utilization of unlicensed spectrum for carrier aggregation. Since the two technologies employ com-pletely different access protocols and frame transmission times, supporting coexistence with minimal modifications on existing protocols is not an easy task. Current solutions are often based on LTE unilateral adaptations, being LTE in unlicensed bands still under definition. In this paper, we demonstrate that it is possible to avoid a subordinated role for WiFi nodes, by simply equipping WiFi nodes with a sensing mechanism based on adaptive tunings of the …
Technique of Statistical Validation of Rival Models for Fatigue Crack Growth Process and Its Identification
2011
The development of suitable models of stochastic crack growth process is important for the reliability analysis of fatigued structures as well as the scheduling of inspection and repair/replacement maintenance. Based on modifications of the solution of the deterministic differential equation for the crack growth rate, where a stochastic nature of this rate is expressed by a random disturbance embedded in the solution of the differential equation, the simple stochastic models are presented for practical applications. Each of these models represents a stochastic version of the solution of the Paris-Erdogan law equation. The models take into account the random disturbance parameters while main…
Nurse Scheduling Problem: An Integer Programming Model with a Practical Application
2012
We use a binary integer programming model to formulate and solve a nurse scheduling problem (NSP) which maximally satisfies nurse preferences. In a practical application of a VA hospital, besides considering the scheduling of two types of nurses (registered nurses and licensed practical nurses), two other types of employees (nursing assistants and health care techs), one nurse manager, and a clinical nurse leader are also included in our model. Most of these employees are working full-time. In addition, we distinguish the schedule of weekdays and weekends with different requirements and different preferences for employees. Besides the requirements for each shift, we consider requirements fo…
Spectral evolution simulation on leading multi-socket, multicore platforms
2011
Spectral evolution simulations based on the observed Very Long Baseline Interferometry (VLBI) radio-maps are of paramount importance to understand the nature of extragalactic objects in astrophysics. This work analyzes the performance and scaling of a spectral evolution algorithm on three leading multi-socket, multi-core architectures. We evaluate three parallel models with different levels of data-sharing: a sharing approach, a privatizing approach and a hybrid approach. Our experiments show that the data-privatizing model is reasonably efficient on medium scale multi-socket, multi-core systems (up to 48 cores) while regardless algorithmic and scheduling optimizations, sharing approach is …
Efficient Switches with QoS Support for Clusters
2007
Current interconnect standards providing hardware support for quality of service (QoS) consider up to 16 virtual channels (VCs) for this purpose. However, most implementations do not offer so many VCs because they increase the complexity of the switch and the scheduling delays. We have shown that this number of VCs can be significantly reduced, because it is enough to use two VCs for QoS purposes at each switch port. In this paper, we cover the weaknesses of that proposal and, not only we reduce VCs, but we also improve performance due to the flexibility assigning buffer memory.
On the development of a communication-aware task mapping technique
2004
Clusters have become a very cost-effective platform for high-performance computing. In these systems, although currently existing networks actually provide enough bandwidth for the existing applications and workstations, the trend is towards the interconnection network becoming the system bottleneck. Therefore, in the future, scheduling strategies will have to take into account the communication requirements of the applications and the communication bandwidth that the network can offer. One of the key issues in these strategies is the task mapping technique used when the network becomes the system bottleneck.In this paper, we propose a communication-aware mapping technique that tries to mat…
EECDC-MAC: An energy efficient cooperative duty cycle MAC protocol
2012
In this paper, we propose a novel energy efficient cooperative duty cycle MAC (EECDC-MAC) protocol in which sensor nodes use fixed wakeup rendezvous scheduling to exchange messages and a cooperative transmission mechanism to avoid overuse of nodes with lower residual energy. Numerical results demonstrate that the EECDC-MAC protocol can prolong the entire network longevity efficiently in comparison with an existing cooperative duty cycle MAC protocol, CDC-MAC, and another popular duty cycle MAC protocol, prediction wakeup MAC (PW-MAC) protocol.
Assessing different methodologies for irrigation scheduling in protected environment: a case study of green bell pepper
2022
This research aimed at assessing four different methodologies to estimate daily irrigation depth, based on the monitoring of soil water status (soil water content sensors, SWS, and tensiometers, TS) and atmospheric evaporative demand (weighing lysimeter, WL, and Piché evaporimeter, PE), of green bell pepper Capsicum annum L.) cultivated in a greenhouse. Furthermore, two different strategies to apply the daily irrigation depths, i.e., single watering (at 8:00 a.m.) or split into two equal applications (at 8:00 a.m. and at 4:30 p.m.), were also investigated. The experiment was conducted in a completely randomized design and according to a 4 × 2 factorial scheme with eight replications. The st…
Using field measurements and FAO-56 model to assess the eco-physiological response of citrus orchards under regulated deficit irrigation
2017
[EN] Micro-irrigation is considered one of the most efficient water distribution systems and allows increasing water use efficiency if coupled with effective water-saving irrigation management strategies as regulated deficit irrigation (RDI) or partial root-zone drying (PRD) techniques. However, application of these strategies makes it crucial the real-time monitoring of soil and crop water status, in order to identify appropriate irrigation scheduling parameters (irrigation timing and doses) and to prevent irreversible damage of plant system and/or crop yield reductions. Even if midday stem water potential (MSWP) is considered one of the most affordable indicator for direct determinations …
Continuous determination of fruit tree water-status by plant-based sensors
2017
Recently, climate change has caused shortages of water worldwide, especially in semi-arid and arid regions. Several irrigation strategies have been studied with the aim of saving water overuse in agriculture. In the past most of the attention was directed towards soil water content, but recently the focus has moved to plant responses to water deficit. In recent years, crop evapotranspiration (ETc) obtained from reference evapotranspiration (ET0) and crop coefficients (Kc), has become common for irrigation scheduling in several crops, but it does not provide precise insights on the tree water status. Today an increasing focus is being given to plant-based sensors for the continuous monitorin…