The University of Northampton: Northampton Open Journals
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The In-depth Study on Universal AWT-RTT-HC-MTT Computation for Passenger Demand beyond Elevator Contract Capacity by Interlinked Monte Carlo Simulation
No full textThe traditional elevator system design is based on an initial calculation of the round-trip time (RTT) and associated parameters of pure incoming traffic during uppeak, followed by real-time computer simulation. For the calculation, it is always assumed that the passenger demand in one round-trip does not exceed the contract capacity of the elevator. One approach in the middle between the two is by Monte Carlo simulation (MCS) which is closer to real-time computer simulation but could produce consistent and converging results of parameters required by the conventional calculation approach. A previous article [16] (So and Al-Sharif 2023) studies the universal RTT, handling capacity (HC), and mean transit time (MTT) of a round-trip when the passenger demand exceeds the contract capacity of the elevator. The term, “Universal”, refers to the use of a generic PDFOD (probability distribution function origin-destination) matrix to generate passengers’ origin and destination floors. In this article, one more parameter, the average waiting time (AWT), has been added to the study. Waiting time is not well defined on an individual round-trip basis. Here, the method of interlinked Monte Carlo simulation (iL-MCS) is adopted to study the traffic performance of the elevator through a series of continuous round-trips so that the average waiting time of passengers could be estimated. Similar as before, the passenger demand of every round-trip exceeds the contract capacity of elevator. In this way, the passenger demand when the AWT becomes unacceptable can be found, like the RTT, HC and MTT estimated in the previous article
The Evaluation of EN 81-20 Requirements with regard to Car Deceleration during Buffering Process of Lifts
No full textBuffers at lifts comprise a certain design. This design and the resulting buffer properties have to cover the different modes of operation. For lift buffers this means the coverage of varying car masses at the specified speed. The paper shows the basic characteristics of hydraulic buffers. Following a sketch on the requirements on buffers according to EN 81-20 is given. A software for the detailed simulation of buffer collisions is presented. In the main part of the paper this software is used to calculate and to analyze two cases of buffer collisions at maximum and minimum loading each. The results out of these simulations are shown and discussed in brief
Uncontrolled Overspeed
No full textThe major part of the design and specification of equipment for the arrest or prevention of overspeed, particularly the safety gear/overspeed governor combination, concerns itself with the performance when carrying rated load, or, in the event of upward overspeed, zero load in the car. In particular, specification is concerned with performance of safety equipment in the face of suspension failure, however unlikely that might be. This paper sets out to investigate the performance of overspeed protection when there is a partial load in the car, whether with a failed suspension or not, and to discuss the opportunities in this respect provided by the introduction of the so-called rope brake
An In-depth Study on RTT-HC-MTT Relationship for Passenger Demand beyond Elevator Contract Capacity by Simulation
No full textThe traditional elevator system design practice is to calculate the round trip time (RTT) and associated parameters of pure incoming traffic during up-peak, followed by real-time computer simulation. Recent studies indicated that the normal traffic is much more complicated, consisting of a mixture of incoming, outgoing and interfloor patterns. The Universal RTT, under such complicated traffic patterns, was analytically developed eight years ago based on the concept of an appropriate origindestination matrix describing the passenger transit probability, and verified by Monte Carlo simulation. That model is based on the assumption that the total number of passengers demanding service within one round trip is limited to the elevator contract capacity, which is in line with the traditional up-peak incoming RTT formula. The idea of extending the consideration to beyond the contract capacity was initiated two years ago. In this article, an in-depth study on such consideration is carried out so that the performance such as RTT, handling capacity (HC) and mean transit time (MTT) etc. under different traffic patterns is evaluated and analyzed with the help of Monte Carlo simulation. This article may help designers optimally size an elevator system during the RTT calculation stage without oversizing it if the prevalent traffic patterns of the building are known
Towards a global traffic control (dispatcher) algorithm - interface prototype design
No full textThis paper presents an overview of the design and development of a prototype Global Dispatcher Interface (GDI) for the control of a group of lifts. The role of the dispatcher is to assign passenger calls to the optimal lift in a group, as decided by a dispatcher algorithm. The GDI is independent of the underlying algorithm, which may be distributed remotely, and provides a standard means through which all interactions may occur. To warrant the “Global” appellation the GDI must support any of the currently available, as well as anticipated, call station modes, types and configurations of cars, topology of control equipment and buildings. The design process is a continuation of a recognised Software Development Lifecycle, centred on Use Cases in a UML model, the initiation of which is covered in a previous paper. Significant diagrams from the model are presented and discussed to illustrate the evolution of the prototype design. One of the requirements, resulting from analysis of the Use Cases, identifies that the GDI design must be compatible with a publish-and-subscribe architecture and a RESTful interface is selected for this purpose. Where possible, the prototype design uses open standards with an emphasis on demonstrating aspects that are specific to lift system dispatcher operation, while attempting to demonstrate independence from implementation details such as programming language, network protocols, etc. The Standard Elevator Information Schema is particularly relevant and fulfils these objectives. The operation of the working prototype, in conjunction with simulated lifts and passengers, is presented as a validation of the design
Dynamic extension for Ideal Kinematics
No full textThis paper presents a new set of equations for modelling kinematic profiles using a combination of mathematical and computational techniques. The implementation of these equations will extend the capabilities of the kinematic model to produce asymmetric and dynamic profiles. This will provide a more accurate model for standard lift systems as well as enable the modelling of more complex systems
The trip function of a lift
No full textThis paper deals with the mathematical derivation of the continuous trip function of a lift. This derivation applies not only to a lift but also to any mass inert mechanism that starts moving from standstill, runs up to a maximum speed or rated speed, to continue for some time, and then stops again after deceleration at completion of its trip along a predetermined track. The trip function determines the traveled distance and the (total) travel time in a continuous relationship with time, rated speed, maximum acceleration and jerk. All kinematic cases of the trip function, such as a short trip without reaching the rated speed, are treated with elaboration of the corresponding specific equations for the total traveled time, maximum achieved speed, etc. The results of the continuous trip function are compared to the results of the equations given in the literature (CIBSE Guide D Annex A2), which are based on a simplified model of the trip function. The conclusion is that the equations based on the simplified model are sufficient accurate for the calculation of handling capacity, journey times, etc. of lifts
Modernizations in the post-pandemic world
No full textAbstract. Modernization has been a part of the lift industry for a very long time. There are buildings that are over 100 years old that have been modernized multiple times but continue to use the original direct current machine. Both societal changes and technical innovations will make the modernizations of the very near future different from the modernizations of the present.The motivations for modernization, the societal changes, and the technical innovations will be reviewed. The benefits of the next generation modernization will also be explored
Analytical RTT Estimation of a 3-D Elevator System by Exact Stop Positions - Extension to Multi-floor and Non-uniform Population Applications
No full text3-dimensional (3-D) elevator systems will be the industrial trend. Traditionally, designers first perform a calculation on traffic analysis to get an overall concept and then go ahead to carry out simulation to obtain details. This tradition is still maintained throughout the world. In one previous article, a “Scanner” approach was adopted to convert a 2-D or 3-D path of scanning to a 1-dimensional line and a sophisticated origin/destination stops matrix was generated to calculate the round trip time (RTT). A probability matrix was generated with an assumption that only one floor was served in one round trip. In a more recent article, by using order statistics, a method to break down a series of repeatable stops in a 3-D system into several series of non-repeatable stops was developed for easy reasoning by designers. Here, a uniform population distribution of all potential stops and a single floor service were assumed. In this article, by following the concept of the most recent article, RTT calculation could be extended to non-uniform population distribution of stops and multi-floor applications which may be the most general approach to calculate the RTT of a truly 3-D elevator system
Fundamental study on rope vibration suppression by middle transfer floor using risk information
No full textLifts are essential for means of vertical transportation. Recently, the lifts installed in the high-rise buildings are long travel, thus the lift ropes are becoming longer. The natural period of the high-rise buildings is longer than that of the conventional buildings. In addition to the lift rope becomes longer, the natural period of the lift ropes become longer. Accordingly, the natural period of the lift ropes gets closer to the natural period of the building. Consequently, the lift ropes might be hooked to the equipment of wall when the lift ropes vibrate by an external force, such as a strong wind and earthquake. Furthermore, secondary accident such as containment of passengers and lift service stop may occur. In the Great East Japan Earthquake in 2011, 2015 cases of problem such as the catch and the damage of lift ropes have been reported. Operation of lifts after earthquakes are required for the security of the refuge course. Accordingly, the analytical method for comparative evaluation is investigated in this study. Furthermore, method to prevent a catch by vibration reduction of the lift ropes is investigated. In the previous research, it was confirmed that the division of the lift stroke is effective for reducing the response of the rope. When the lift stroke was equally divided. The displacement of the upper lift became larger than that of the other lift. Accordingly, the effectiveness of the division ratio of lift stroke was examined in this report. We investigated the catching of the lift rope using differential analysis and risk assessment. As the result, the displacement of the upper lift was decreased by the apposite division ratio. The probability of catching rope of the upper lift is reduced. Furthermore, it was confirmed that the risk of the catching rope reduces in probabilistic risk assessment.Lifts are essential for means of vertical transportation. Recently, the lifts installed in the high-rise buildings are long travel, thus the lift ropes are becoming longer. The natural period of the high-rise buildings is longer than that of the conventional buildings[1]. In addition to the lift rope becomes longer, the natural period of the lift ropes become longer. Accordingly, the natural period of the lift ropes gets closer to the natural period of the building. Consequently, the lift ropes might be hooked to the equipment of wall when the lift ropes vibrate by an external force, such as a strong wind and earthquake. Furthermore, secondary accident such as containment of passengers and lift service stop may occur. In the Great East Japan Earthquake in 2011, 2015 cases of problem such as the catch and the damage of lift ropes have been reported [2]. Operation of lifts after earthquakes are required for the security of the refuge course. Accordingly, the analytical method for comparative evaluation is investigated in this study. Furthermore, method to prevent a catch by vibration reduction of the lift ropes is investigated. In the previous research, it was confirmed that the division of the lift stroke is effective for reducing the response of the rope. When the lift stroke was equally divided. The displacement of the upper lift became larger than that of the other lift. Accordingly, the effectiveness of the division ratio of lift stroke was examined in this report. We investigated the catching of the lift rope using differential analysis and risk assessment. As the result, the displacement of the upper lift was decreased by the apposite division ratio. The probability of catching rope of the upper lift is reduced. Furthermore, it was confirmed that the risk of the catching rope reduces in probabilistic risk assessment