The Orbital Channel Resource Control on Non-Markov Priority Systems of Mass Service Basis. Part 2. Dispatch Method

The article develops a methodology for scheduling an orbital channel resource with operational priority assignment based on the calculation of the parameters of a non-Markov service model with a limited residence time of a request in the system, which differs from known methods in that it takes into account the priority of various network subscribers, taking into account the high dynamics of their movement and the average waiting time in the service system with priority in the allocation of the orbital channel resource of the satellite command-relay system. The analysis of the influence of service quality indicators of information data flows is carried out.It is shown that the developed method of priority scheduling makes it possible to meet the requirements for the quality of service. A complex of experimental studies was carried out, which showed the possibility of ensuring the required level of stability with the deterioration in difficult conditions of radio electronic equipment, which made it possible to formulate practical proposals for improving the complex of coordination and distribution of resources of in the satellite command relay system.

Performance Evaluation of the Priority Multi-Server System MMAP/PH/M/N Using Machine Learning Methods

In this paper, we present the results of a study of a priority multi-server queuing system with heterogeneous customers arriving according to a marked Markovian arrival process (MMAP), phase-type service times (PH), and a queue with finite capacity. Priority traffic classes differ in PH distributions of the service time and the probability of joining the queue, which depends on the current length of the queue. If the queue is full, the customer does not enter the system. An analytical model has been developed and studied for a particular case of a queueing system with two priority classes. We present an algorithm for calculating stationary probabilities of the system state, loss probabilities, the average number of customers in the queue, and other performance characteristics for this particular case. For the general case with K priority classes, a new method for assessing the performance characteristics of complex priority systems has been developed, based on a combination of machine learning and simulation methods. We demonstrate the high efficiency of the new method by providing numerical examples.

A Fluid-Diffusion-Hybrid Limiting Approximation for Priority Systems with Fast and Slow Customers

The paper “Fluid-Diffusion-Hybrid (FDH) Approximation” proposes a new heavy-traffic asymptotic regime for a two-class priority system in which the high-priority customers require substantially larger service times than the low-priority customers. In the FDH limit, the high-priority queue is a diffusion, whereas the low-priority queue operates as a (random) fluid limit, whose dynamics are driven by the former diffusion. A characterizing property of our limit process is that, unlike other asymptotic regimes, a non-negligible proportion of the customers from both classes must wait for service. This property allows us to study the costs and benefits of de-pooling, and prove that a two-pool system is often the asymptotically optimal design of the system.

The Orbital Channel Resource Control on NonMarkov Priority Systems of Mass Service Basis. Part 1.Operational Distribution Model

In work systems analysis of process of target functioning of the satellite command relay system (SCRS) in the conditions of a difficult radio-electronic situation is carried out. The carried-out analysis of perspectives of development of a subsystem of relaying of SKRS of orbital grouping of spacecrafts of remote sensing of Earth, allowed to draw a conclusion on features of a stage of coordination planning of the means of a subsystem of relaying consisting in distribution of SKRS the orbital channel resource (OCR) on the basis of the non-Markov priority systems of service. The model of operational distribution of ROC of a subsystem of relaying on the basis of the priority systems of service in which, unlike the known models, time of stay of the request in a system is limited is received, limits for a type of distribution of holding time of requests are lifted and also expression for calculation of the initial moments of distribution of waiting time of messages of different priorities is received. Use of model allows to evaluate the probability of untimely delivery of details and also to provide required figures of merit of service of priority flows and at the expense of it to provide the required connectivity and stability of SKRS in general.

PENILAIAN RISIKO KEGAGALAN BENDUNGAN KEDUNGOMBO SEBAGAI DASAR PRIORITAS PEMELIHARAAN BENDUNGAN

A dams must always be maintained for their performance, function, and safety, so it is necessary to carry out various maintenance, repairs, and rehabilitation on dams that have been built and operating. Priority systems for the implementation of repair and rehabilitation of dams can be arranged based on the status of safety hazards or the level of risk of failure due to natural disasters or other consequences. Based on this, it is necessary to carry out an assessment of the dam to estimate the magnitude of the risk to the dam. According to the Risk Analysis Guidelines, the estimation of the probability of failure can be done using two methods, namely the traditional method and the event tree method. Based on the results of assessment analysis, the risk probability of the Kedungombo Dam with the traditional method and the event tree method is 4,010 x 10-1 and 1,548 x 10-3 where the acceptable limit conditions for the existing dam are a maximum of 1,000 x 10-5. The risk probability value of the Kedungombo Dam does not meet the requirements of an acceptable risk value. Therefore, it is necessary to recommend risk reduction for the risk assessment results. ABSTRAKBendungan harus selalu dijaga kinerja operasi, fungsi, dan keamanannya, sehingga perlu dilakukan berbagai kegiatan pemeliharaan, perbaikan, dan rehabilitasi pada bendungan yang sudah terbangun dan beroperasi. Sistem prioritas pada pelaksanaan kegiatan perbaikan dan rehabilitasi pada bendungan dapat disusun berdasarkan status bahaya bendungan dari segi keamanan atau besarnya risiko terhadap kegagalan bendungan akibat bencana alam maupun akibat lain. Berdasarkan hal tersebut, maka perlu dilakukan penilaian risiko pada bendungan untuk memperkirakan besarnya risiko bahaya pada bendungan. Berdasarkan Pedoman Analisis Risiko, perkiraan probabilitas kegagalan dapat dilakukan dengan dua metode yaitu metode tradisional dan metode pohon kejadian (event tree). Berdasarkan hasil analisis penilaian risiko, probabilitas risiko Bendungan Kedungombo metode tradisional dan metode pohon kejadian sebesar 4,010 x 10-1 dan 1,548 x 10-3 dimana syarat batas yang dapat diterima untuk bendungan eksisting maksimum 1,000 x 10-5. Nilai probabilitas risiko Bendungan Kedungombo tidak memenihi syarat nilai risiko yang dapat diterima. Dengan demikian, diperlukan rekomendasi tindakan pengurangan risiko untuk risiko hasil penilaian tersebut.

Diffusion Model of Preemptive-Resume Priority Systems and Its Application to Performance Evaluation of SDN Switches

The increasing use of Software-Defined Networks brings the need for their performance analysis and detailed analytical and numerical models of them. The primary element of such research is a model of a SDN switch. This model should take into account non-Poisson traffic and general distributions of service times. Because of frequent changes in SDN flows, it should also analyze transient states of the queues. The method of diffusion approximation can meet these requirements. We present here a diffusion approximation of priority queues and apply it to build a more detailed model of SDN switch where packets returned by the central controller have higher priority than other packets.

Healthcare students support opt-out organ donation for practical and moral reasons

Background and purposeChanges to deceased organ donation policy in the USA, including opt-out and priority systems, have been proposed to increase registration and donation rates. To study attitudes towards such policies, we surveyed healthcare students to assess support for opt-out and priority systems and reasons for support or opposition.MethodsWe investigated associations with supporting opt-out, including organ donation knowledge, altruism, trust in the healthcare system, prioritising autonomy and participants’ evaluation of the moral severity of incorrectly assuming consent in opt-in systems (‘opt-in error’) or opt-out systems (‘opt-out error’), by conducting an online survey among healthcare students at a large academic institution.ResultsOf 523 respondents, 86% supported opt-out, including 53% who strongly supported the policy. The most popular reason for supporting opt-out was the potential for increased donation rates, followed by convenience for those not registered but willing to donate. The most popular reason for opposing opt-out was the belief that presuming consent is morally wrong. Those strongly supporting opt-out viewed the opt-in error as more morally unacceptable, and had higher knowledge and altruism scores. Those opposing opt-out viewed the opt-out error as more unacceptable, and had higher autonomy scores. 48% of respondents supported priority within opt-in systems; 31% supported priority in opt-out.ConclusionsThere is strong support for opt-out organ donation among healthcare students, influenced by both practical and moral considerations.