Impacts of Metering-Based Dynamic Priority Schemes

Several works published over the last two decades have shown for a stylized set-up with homogeneous users that metering-based priority (MBP) schemes may generate Pareto improving departure time adjustments similar to those induced by congestion pricing, but without any financial transaction. We investigate whether MBP (i) still generates significant savings and (ii) remains Pareto-improving, with various sources of heterogeneity (in schedule flexibility, desired arrival time, and capacity usage). We consider two types of schemes: one where the priority status is allocated randomly (R-MBP) and another (HOV-MBP), which only prioritizes users with small capacity usage (e.g., carpoolers). We find that the relative total cost savings of R-MBP decrease with heterogeneity in flexibility, but may increase with heterogeneity in desired arrival time. It fails however to be Pareto-improving, as nonprioritized users are almost systematically worse-off. HOV-MBP circumvents this issue by generating an ordering effect and a modal shift, which both contribute to a better distribution of benefits among users. Under favorable circumstances, they may even restore a Pareto improvement. Overall, MBP appears as a realistic way to alleviate congestion, scoring well both in terms of efficiency and social acceptability.

The Method of Operational Planning of Group Actions of Aircraft in the "Air Taxi" Mode

The article is devoted to the development of algorithms for operational planning of routes for a group of aircraft (AC). We consider group actions of small and unmanned aircraft in the "air taxi" mode, when there is no regular flight schedule between the points of destination, and requests are received "on call" for flights to points whose composition is unknown in advance and is of a random nature. The multicriteria task of planning a group flight in the "air taxi" mode is being solved. The solution to this problem is proposed using the apparatus of the queuing theory, according to which the system under consideration belongs to the class of multichannel queuing systems with waiting. A method for solving the problem of operational planning of aircraft actions is proposed. An algorithm for group target distribution of new claims between aircraft is developed on the basis of a modified minimax criterion for assigning the nearest aircraft for an object with a maximum service time. The developed algorithm is based on the following four main operations: in the first operation, priority unserved targets are selected according to the criterion of assigning a dynamic priority; in the second operation, the formed list is ranked according to another criterion, taking into account the importance and total distance of each ground object from the aircraft group, in three this operation selects the object with the maximum rank, and for it the task of assigning "own" aircraft is solved according to the third criterion of maximum proximity, in the fourth operation the conditions of non-intersection of the group flight routes are checked. A computer model of the system for servicing requests in the air taxi mode has been developed. The developed model makes it possible to analyze various scheduling algorithms, as well as to determine at each step the number of free claims and the number of free and busy aircraft. A comparison is made between the well-known in the theory of queuing and the proposed minimax approaches. It is shown that, in comparison with the known variants of scheduling in the queuing theory, on the basis of the proposed approach, the optimal number of used aircraft is achieved.

Dynamic Priority Real-Time Scheduling on Power Asymmetric Multicore Processors

The use of real-time systems is growing at an increasing rate. This raises the power efficiency as the main challenge for system designers. Power asymmetric multicore processors provide a power-efficient platform for building complex real-time systems. The utilization of this efficient platform can be further enhanced by adopting proficient scheduling policies. Unfortunately, the research on real-time scheduling of power asymmetric multicore processors is in its infancy. In this research, we have addressed this problem and added new results. We have proposed a dynamic-priority semi-partitioned algorithm named: Earliest-Deadline First with C=D Task Splitting (EDFwC=D-TS) for scheduling real-time applications on power asymmetric multicore processors. EDFwC=D-TS outclasses its counterparts in terms of system utilization. The simulation results show that EDFwC=D-TS schedules up to 67% more tasks with heavy workloads. Furthermore, it improves the processor utilization up to 11% and on average uses 14% less cores to schedule the given workload.

Against Jazz Combo Theories of Meaning and Reference

The “jazz combo theory” captures the common spirit of various theories that reject reference and the “bottom up” approach to the problem of objective representational content. We can imagine the members of a jazz combo initially playing together without any shared musical norms. But they continually adjust to one another until norms emerge and are mutually endorsed. Players start holding one another to these norms, and it’s this that gives the sounds they produce—what would otherwise be mere noise—determinate musical content. Similarly, on the jazz combo theory, what would otherwise be productions of meaningless strings by language users, come to constitute determinate linguistic acts with determinate propositional contents, by virtue of the users adopting, and holding one another to, a shared set of linguistic and discursive norms. This chapter argues that jazz combo theorists overstate the case against reference, although they’re right in stressing the importance of norms and their dependence on social interaction. Jazz combo theorists tend to reject bottom-up approaches, including causal theories, because they take those approaches to be incompatible with the explanatory priority of the sentence and to fail to bridge the supposed gap between cause and norm. A number of conceptual tools are introduced to counter their arguments and to defend the consistency of the dynamic priority of the sentence, the syntactic correlativity of sentences and their constituents, and the semantic priority of constituents.

Dynamic approach to minimize overhead and response time in scheduling periodic real-time tasks

In real-time systems, a task or a set of tasks needs to be executed and completed successfully within a predefined time. Those systems require a scheduling technique or a set of scheduling methods to distribute the given task or the set of tasks among different processors or on a processor. In this paper, a new novel scheduling approach to minimize the overhead from context switching between several periodic tasks is presented. This method speeds up a required response time while ensuring that all tasks meet their deadline times and there is no deadline miss occurred. It is a dynamic-priority technique that works either on a uniprocessor or several processors. In particular, it is proposed to be applied on multiprocessor environments since many applications run on several processors. Various examples are presented within this paper to demonstrate its optimality and efficiency. In addition, several comparison experiments with an earlier version of this approach were performed to demonstrate its efficiency and effectiveness too. Those experiments showed that this novel approach sped up the execution time from 15% to nearly around 46%. In addition, it proved that it reduced the number of a context switch between tasks from 12% to around 50% as shown from simulation tests. Furthermore, this approach delivered all tasks/jobs successfully and ensured there was no deadline miss happened.