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2022 ◽  
Varun Gupta ◽  
Jiheng Zhang

The paper studies approximations and control of a processor sharing (PS) server where the service rate depends on the number of jobs occupying the server. The control of such a system is implemented by imposing a limit on the number of jobs that can share the server concurrently, with the rest of the jobs waiting in a first-in-first-out (FIFO) buffer. A desirable control scheme should strike the right balance between efficiency (operating at a high service rate) and parallelism (preventing small jobs from getting stuck behind large ones). We use the framework of heavy-traffic diffusion analysis to devise near optimal control heuristics for such a queueing system. However, although the literature on diffusion control of state-dependent queueing systems begins with a sequence of systems and an exogenously defined drift function, we begin with a finite discrete PS server and propose an axiomatic recipe to explicitly construct a sequence of state-dependent PS servers that then yields a drift function. We establish diffusion approximations and use them to obtain insightful and closed-form approximations for the original system under a static concurrency limit control policy. We extend our study to control policies that dynamically adjust the concurrency limit. We provide two novel numerical algorithms to solve the associated diffusion control problem. Our algorithms can be viewed as “average cost” iteration: The first algorithm uses binary-search on the average cost, while the second faster algorithm uses Newton-Raphson method for root finding. Numerical experiments demonstrate the accuracy of our approximation for choosing optimal or near-optimal static and dynamic concurrency control heuristics.

Markus Kroneis ◽  
René Scheerer ◽  
Lars Bobach ◽  
Dirk Bartel

A tribological highly stressed contact in the actuating system of axial piston machines is located between the control piston and the control chamber. This paper presents a new type of component test rig for measuring the frictional force and the gap heights between piston and cylinder. For this purpose, the original system is reduced to the actuator system, whereby the real kinematics and the loading forces are maintained. The axial movement of the control piston and the pressure in the control chamber can be configured individually. The measurement results of different parameter variations are compared with the results of the simulation. The simulation based on a coupled multibody and TEHL simulation with a transient, three-dimensional, thermal elastohydrodynamic contact calculation.

2022 ◽  
Vol 14 (2) ◽  
pp. 722
Di Feng ◽  
Chunfu Lu ◽  
Shaofei Jiang

Manufacturing small- and medium-sized enterprises (SMEs) play a crucial role in the economic development and resource consumption of most regions. Conceptually, a product-service system (PSS) can be an effective way to improve the sustainability of manufacturing SMEs. However, the construction of PSSs requires enterprises to integrate a large number of product and service resources. Moreover, current PSS design methods mostly construct a new set of highly service-oriented PSS solutions based on customer needs while seldom considering the combination of acceptability and sustainability for manufacturing SMEs at the initial stage of design, which may lead to the difficulties in applying PSS solutions beyond enterprise integration capacity or result in the waste of existing product resources. Instead of constructing a new PSS solution, this paper proposes the treatment of existing product modules as the original system. The PSS solution is iteratively constructed with the upgrade of the original system in a gradual way, which is driven by systematic performance (this process can be suspended and repeated). Phased iterative design solutions can be applied by manufacturing SMEs according to their development needs. The analytic hierarchy process (AHP), Lean Design-for-X (LDfX), design structure matrix (DSM), and Pearson correlation coefficient (PCC) are combined in an iterative design process from customer needs and system performances to PSS solutions. The feasibility of the proposed method is verified through the iterative design case from electric pallet trucks to warehousing systems. It is proved that this method is more sustainable and easier to be accepted by manufacturing SMEs than existing PSS design methods through in-depth interviews with entrepreneurs.

2022 ◽  
Vol 183 (1-2) ◽  
pp. 1-31
Raymond Devillers

In order to speed up the synthesis of Petri nets from labelled transition systems, a divide and conquer strategy consists in defining decompositions of labelled transition systems, such that each component is synthesisable iff so is the original system. Then corresponding Petri Net composition operators are searched to combine the solutions of the various components into a solution of the original system. The paper presents two such techniques, which may be combined: products and articulations. They may also be used to structure transition systems, and to analyse the performance of synthesis techniques when applied to such structures.

Kaixiao Tian ◽  
Emmanuel Detournay ◽  
He Zhang

Abstract This work describes an alternative formulation of a system of nonlinear state-dependent delay differential equations (SDDDEs) that governs the coupled axial and torsional vibrations of a 2 DOF drillstring model considering a Polycrystalline Diamond Compact (PDC) bit with realistic cutter layout. Such considerations result in up to 100 state-dependent delays due to the regenerative effect of the drilling process, which renders the computational efficiency of conventional solution strategies unacceptable. The regeneration of the rock surface, associated with the bit motion history, can be described using the bit trajectory function, the evolution of which is governed by a partial differential equation (PDE). Thus the original system of SDDDEs can be replaced by a nonlinear coupled system of a PDE and ordinary differential equations (ODEs). Via the application of the Galerkin method, this system of PDE-ODEs is transformed into a system of coupled ODEs, which can be readily solved. The algorithm is further extended to a linear stability analysis for the bit dynamics. The resulting stability boundaries are verified with time-domain simulations. The reported algorithm could, in principle, be applied to a more realistic drillstring model, which may lead to an in-depth understanding of the mitigation of self-excited vibrations through PDC bit designs.

2022 ◽  
pp. 179-195
Péter Pavletits

The purpose of my study. The main target of my study was to survey the golden age of the Hungarian narrow-gauge railways from the and of WWII until the Transport Policy Concept of 1968. Beside the survey, I examined the impact of the Transport Policy Concept of 1968 on the narrow -gauge railways, especially at the Szerencs-Prügy narrow-gauge railway. Applied methods. Literature review including the history of the Hungarian narrow-gauge railways in the time frame of World War II and 1968. We involved sources from monographies, our own data from researches of archives, especially from MÁV Archive, and local newspapers of the above mentioned period. Outcomes. After WWII ended, notable narrow-gauge railway constructions begun, so we can call apostrophe the quarter century as the second golden age there history, however from the early 1960’s the communist regime did not sympathize with narrow-gauge railways (New Economic Mechanism in 1968). Therefore the railway system, which was more than 5000 kilometres long before, constantly began to diminish. Nowadays only 5% of the original system has left (245 kilometers) and today narrow-gauge railways – beside four lines - have only touristical funtion. Economic policy recommendations. With the implementation of the transport policy concept, 30% of the low-traffic lines and stations were closed by diverting their traffic to the road. These measures have done a lot of damage to domestic transport. The rate of closure of the sidelines was well above the level of similar measures of the European railways, but the road development did not take place to the extent planned and the loading engineering and other development measures necessary for the successful implementation of the concept were largely cancelled. The leftover railway network could not become an engine for the development of transport, its performances decreased and road transport took over the tasks of the railways even in areas where the railway proved to be more uneconomic.

Sensors ◽  
2022 ◽  
Vol 22 (1) ◽  
pp. 317
Alexander Zuev ◽  
Alexey N. Zhirabok ◽  
Vladimir Filaretov ◽  
Alexander Protsenko

The problem of fault identification in electric servo actuators of robot manipulators described by nonstationary nonlinear dynamic models under disturbances is considered. To solve the problem, sliding mode observers are used. The suggested approach is based on the reduced order model of the original system having different sensitivity to faults and disturbances. This model is realized in canonical form that enables relaxing the limitation imposed on the original system. Theoretical results are illustrated by practical example.

2021 ◽  
Vol 54 (6) ◽  
pp. 37-54
Lyubov A. Buryakova ◽  
Alexey G. Buryakov ◽  

The problem of research. The relevance of the research is due to the urgent need to find new approaches to the musical development of students in general education, which makes it significant to refer to the experience of France in connection with the existence in the country of an original model of musical education with an established system of multifaceted partnerships controlled by the bodies of the Ministry of National Education and the Ministry of Culture of France. The purpose of the article: scientific and practical justification of the need to develop a Russian strategy of musical development based on the interaction of educational and cultural organizations. Materials and methods. As a methodological basis, a system-structural approach was used, which made it possible to conceptualize the data obtained as a result of the analysis of sources, as well as in the process of personal communication with French colleagues. The results of the study. The mechanism of the studied interaction in various forms of educational, extracurricular and out-of-school musical activities is based on a clearly structured scheme of cooperation between schools and partner structures in the field of culture and art at the state (conceptual), academic (coordination) and local (performing) levels. The impetus for the construction of this system of partnerships was the recognition by the pedagogical community and the authorities of France of the priority of musical education as a powerful stimulant for the development of personal, intellectual and creative abilities of students necessary for successful implementation in any field of activity. Discussion and conclusion. The initial impulse to the emergence of the concept of attracting artistic and cultural structures in the musical and educational field was the introduction in the early 80s of the twentieth century of the original system of professional and amateur musical training of students in the framework of general education in college and lyceum. In the future, the experience of partnership interaction in the field under study gradually spread not only to academic, but also to extracurricular and out-of-school activities. As an important "breakthrough" of the French musical and educational project, a significant contribution to the educational activities of musical and cultural centers of global importance should be recognized. The far-sighted policy of the French authorities aimed at substantial support of artistic, especially musical culture as the basis for the development of the whole society can serve as a strategic guideline for the modernization of the music education system in Russia in terms of developing management schemes and educational technologies based on the interaction of educational institutions with cultural and art institutions.

2021 ◽  
Vol 11 (5) ◽  
pp. 307-348

The article analyzes the general theory of judicial knowledge and proof, its capabilities and implementation in the consideration and resolution of cases of special proceedings in civil, arbitration, administrative proceedings. The approaches to cognitive and evidentiary activities in controversial (claim) and indisputable (special) proceedings are compared. The author considers the original system of collecting, presenting and evaluating evidences, created in the field of voluntary jurisdiction in the countries of civil law, its advantages and disadvantages in comparison with the national tradition of the unity of legal regulation of judicial knowledge and proof. An overview of the current state of the doctrine and practice of proving in special proceedings is given, an opinion is expressed about the need to refine the general provisions on proving in special proceedings. The prospects for the normative establishment of the limits of judicial research in terms of the volume of facts and the depth of their knowledge are outlined. It is stated that in cases of special proceedings, the “standard of proof” has always been higher in comparison with cases of claim proceedings. A number of new rules for establishing the circumstances of cases and proving are proposed: the priority of direct personal perception of the judge in the cognition of facts that are important for the case before proving them; freedom of means of evidence – the ability to use information about the circumstances of the case without restrictions on its sources (means of proof); freedom in choosing the rules for extracting information from a source (means of proof); different regulation of the burden of confirmation and the burden of proof.

Arvind Kumar Prajapati ◽  
Rajendra Prasad

A new model order abatement method based on the clustering of poles and zeros of a large-scale continuous time system is proposed. The clustering of poles and zeros are used for finding the cluster centres. The abated model is identified from the cluster centres, which reflect the effectiveness of the dominant poles of the clusters. The cluster centre is determined by taking [Formula: see text] root of the sum of the inverse of [Formula: see text] power of poles (zeros) in a particular cluster. It is famous that the magnitude of the pole cluster centre plays an important role in the clustering technique for the simplification of large-scale systems. The magnitude of the cluster centres computed by the modified pole clustering method or some other methods based on the pole clustering techniques is large as compared to the proposed technique. The less magnitude of pole cluster centre reflects the better approximations and proper matching of the abated model with the original system. Therefore, the proposed method offers better approximations matching between actual and abated systems during the transient period compared to some other clustering methods, which supports the replacement of large-scale systems by proposed abated systems. The proposed technique is a generalized version of the standard pole clustering technique. The proposed method guarantees the retention of dominant poles, stability and other fundamental control properties of the actual plant in the abated model. The proposed algorithm is illustrated by the five standard systems taken from the literature. The accuracy and effectiveness of the proposed method are verified by comparing the time responses and various performance error indices.

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