Fixed Schedules Research Articles

Software-Defined Network-Based Proactive Routing Strategy in Smart Power Grids Using Graph Neural Network and Reinforcement Learning

Smart power grid relies on sensors and actuators to provide continuous monitoring and precise control functions. Two types of data and command packets are associated with such field devices, namely, periodic fixed scheduling (FS) and emergency-related event-driven (ED) packets, which require different levels of quality-of-service (QoS) support. However, existing routing strategies in smart power grids are not adaptive to network conditions and cannot guarantee differentiated QoS support. To overcome this limitation, we propose a software-defined network (SDN) proactive routing framework in smart grids that takes into account the current and future state of the network while making the routing decisions. The proposed framework offers the following features: (a) It sets up separate queues for ED and FS packets, with higher priority for the ED queue; (b) It predicts the future traffic condition at each switch within the network (congested or not congested) using a graph-neural-network (GNN) model that provides an accurate prediction of the traffic condition despite the sparsity of the ED events; (c) It adopts a reinforcement learning (RL) strategy that establishes an ideal route and updates the queue service rate for each switch along the route following the network’s current and predicted future congestion condition. The proposed framework is tested on the cyber layers of the IEEE 14-bus and 39-bus test systems, and compared to two benchmarks. Our results indicate the superiority of our proposed framework compared with the benchmarks.

Walking and jobs: A comparative analysis to explore factors influencing flexible and fixed schedule workers, a case study of Rasht, Iran

Although walking behavior has been the subject of debate in developed countries, much remains to be learned about this subject in developing countries. Furthermore, it seems likely that the effect of different factors on choosing walking as a commute mode varies across different job groups. Therefore, this research investigated and compared walking behaviors across two job groups with different schedule patterns in the city of Rasht, Iran. The first group is related to those who are flexible schedule (i.e., FLS) workers and the second group refers to people who identify as fixed schedule (FXS) workers. FXS workers attend/leave their workplace during specific period of time which is usually invariant and makes them more time constraint than the second group. Separate behavioral choice models are developed for trips to work using a range of explanatory variables including individual; household; travel; and environmental variables. Results show that females are more likely to walk than males in both groups. Another significant factor is the travel distance which was found with different effects across the studied job groups. Furthermore, it was found that land use features are directly related to walking choice probability of FLS workers.

Quality of service aware traffic scheduling in wireless smart grid communication

The next generation electrical power grid, known as smart grid (SG), requires a communication infrastructure to gather generated data by smart sensors and household appliances. Depending on the quality of service (QoS) requirements, this data is classified into event-driven (ED) and fixed-scheduling (FS) traffics and is buffered in separated queues in smart meters. Due to the operational importance of ED traffic, it is time sensitive in which the packets should be transmitted within a given maximum latency. In this paper, considering QoS requirements of ED and FS traffics, we propose a two-stage wireless SG traffic scheduling model, which results in developing a SG traffic scheduling algorithm. In the first stage, delay requirements of ED traffic is satisfied by allocating the SG bandwidth to ED queues in smart meters. Then, in the second stage, the SG rest bandwidth is going to the FS traffic in smart meters considering maximizing a weighted utility measure. Numerical results demonstrate the effectiveness of the proposed model in terms of satisfying latency requirement and efficient bandwidth allocation.

Traffic Modeling and Optimization in Public and Private Wireless Access Networks for Smart Grids

The major issue in smart grid (SG) communications networks is the latency management of a vast amount of SG traffic in the access network that connects power substations to a large number of SG monitoring devices. There are three possible deployments for the SG access network considered by power industries: 1) a public access network with a mix of SG and human-to-human (H2H) traffic; 2) a private access network exclusively assigned to SG communications; and 3) a mix of private and public access networks, referred to as hybrid access networks. The SG communications traffic is classified as fixed-scheduling (FS) and event-driven (ED). The FS and ED traffic, generated by SG devices, occur on a periodic basis and as a response to electricity supply conditions, respectively. In this paper, we develop traffic models for public, private, and hybrid SG access networks based on queuing theory. By using these models, we derive an expression for the mean queuing delay for each traffic class in each network. We then propose an optimization problem to find the optimal partitioning of the SG traffic in a hybrid access network. The analytical results obtained from the proposed models agree very well with the simulation results.

Alcohol Withdrawal Pharmacotherapy for Inpatients with Medical Comorbidity

Studies show that symptom-triggered dosing is best for treatment of alcohol withdrawal in patients on chemical dependence wards without other illness. On general medical hospital wards, withdrawal may be affected by comorbid medical illness. A clinical trial was undertaken to determine whether there is a difference between symptom-triggered (ST) and fixed-schedule (FS) dosing of lorazepam in patients hospitalized on general medical wards at a university medical center. One hundred eighty-three subjects were assessed by their nurses with the Revised Clinical Institute Withdrawal Assessment for Alcohol (CIWA-Ar) scale. Subjects in the ST arm received lorazepam doses based on CIWA-Ar score. Subjects in the FS arm received scheduled lorazepam with tapering over 4 days. Symptom-triggered dosing for alcohol withdrawal for general medicine inpatients results in less lorazepam given with similar reduction in CIWA-Ar scores for the first 2 days, but a higher proportion of protocol errors.

Influence of Noise Characteristics on Behavioral Aftereffects 1

Two experiments were performed which were designed to replicate and extend the findings of Glass and Singer and others on the aftereffects of noise on performance. In the first, subjects were exposed to 24 min of 95 dBA fixed schedule (FS) or random schedule (RS) intermittent conglomerate noise or to 46 dBA background control (C) noise. After exposure. persistence on insoluble puzzles was least in the RS noise condition and greatest in the C noise condition. In the second experiment. subjects were exposed to 95-dBA intermittent white noise. Recorded nonnal aircraft flyovers, recorded combinations of aircraft noise peaks (AC), and Glass and Singer (GS) conglomerate noise or to 48-dBA background control noise. Following exposure, the GS and AC groups persisted less on the puzzles than the other three groups. In neither experiment was there an effect of noise on routine tasks performed during exposure or on a proofreading task following exposure. Also, there were no significant correlations between subjective ratings of the noise and the performance aftereffects. The significance of these findings is considered ill terms of existing theories.

Attention in the cat: electrophysiological and behavioural studies.

The behaviour of 6 cats was studied in a vigilance task. Each cat was trained to press a pedal on the floor of a training box. A waiting interval of fixed (FI) or variable (VI) duration then followed, after which a stimulus (S), a spot of light or a tone, was presented for a short period of time. The cat gave a correct response if, during this time, it pressed a panel. The animal was then rewarded with food. When an experiment had been completed using one S the cat was trained to respond to the other. The latency of response following the onset of S was measured for each waiting interval in the VI schedules. It was found that the longer latencies were associated with the shorter waiting intervals; that is, the cats responded more quickly to S as expectancy increased. Between the time the pedal and pand were pressed the optic tract (OT) was shocked not more than once and the response of the LGN and visual cortex recorded. The time at which the shock was delivered varied from 1 trial to the next. The responsiveness of the LGN and visual cortex did not vary during the waiting interval in either of the FI schedules or in the VI schedule in which S was a spot of light. However, in the VI schedule in which S was a tone, the responsiveness of the visual cortex to the thalamocortical input declined as the length of the waiting interval increased. No changes were observed at the LGN or in the presynaptic cortical response. These results contrast with those observed during changes in the level of arousal as assessed by the ECoG. When the ECoG passed from the synchronised to the desynchronised state there was an increase in the amplitude of the postsynaptic LGN response to the OT shock, but no change in the responsiveness of the cortex to the increased thalamocortical input. These changes in transmission in the visual pathways are discussed in relationship to the animal's behaviour and to the inferred state of attention.