scholarly journals Estimation of Extreme Loads of the Mi-24 Helicopter During Maneuvers Using Simulation Method

2022 ◽  
Author(s):  
Grzegorz Kowaleczko ◽  
Lukasz Piatkowski
Keyword(s):  
Simulation Model ◽  
Simulation Method ◽  
Main Rotor ◽  
Proper Selection ◽  
Variable Flow ◽  
Helicopter Flight ◽  
Extreme Loads ◽  
Variable Control ◽  
Strength Tests ◽  
Selection Of

The aim of the study is to assess the loads that are transferred from the main rotor and the tail rotor to the helicopter fuselage. These loads change in the various phases of the transient flight as a result of the variable control of the maneuver and as a result of the variable flow around the blades. The knowledge of the loads allows for the proper selection of the level of excitations that should load the fuselage structure during fatigue and strength tests. The simulation model describing the helicopter flight is discussed. This model takes into account the motion of each blade relative to its hinges. Results are shown for two maneuvers - pullup/pushover and diving. The values of extreme loads transferred to the fuselage were obtained.

scholarly journals Analysis of aerodynamics and main rotor loads under stalled conditions of helicopter’s main rotor during the pull-up manoeuvre

2018 ◽  
Vol 48 (1) ◽  
pp. 7-29
Author(s):  
Grzegorz Kowaleczko ◽  
Tomasz Kwaśniak ◽  
Mirosław Nowakowski ◽  
Mirosław Michalczewski
Keyword(s):  
Simulation Model ◽  
Main Rotor ◽  
Helicopter Flight ◽  
Simulation Results ◽  
Aerodynamic Lift

Abstract The article discusses the main features of the applied simulation model of helicopter flight indicating references, where it was elaborated in detail. It focuses on presenting the simulation results of pull-up manoeuvre during which the helicopter does not respond correctly. The reasons for the behaviour as mentioned above were explained based on the results of calculations. The capabilities of the simulation model were used to determine the current loads of particular blades of the helicopter’s main rotor. The results were illustrated by maps of the angles of attack and aerodynamic lift on the surface of the main rotor and the distributions of these parameters along blades on characteristic azimuth for individual manoeuvre phases.

Sensitivity Analysis and Selection of Check Index of Signal Intersection Simulation Model Based on VISSIM

2019 ◽  
Vol 2 (5) ◽  
Author(s):  
Mengda Zhang ◽  
Chenjing Zhou ◽  
Tian-tian Zhang ◽  
Yan Han
Keyword(s):  
Sensitivity Analysis ◽  
Simulation Model ◽  
Optimal Process ◽  
Parameter Calibration ◽  
Index Set ◽  
The Core ◽  
Core Module ◽  
Simulation Parameter ◽  
Simulation Parameters ◽  
Selection Of

Selecting check index quantitatively is the core of the calibration of micro traffic simulation parameters at signal intersection. Five indexes in the node (intersection) module of VISSIM were selected as the check index set. Twelve simulation parameters in the core module were selected as the simulation parameters set. Optimal process of parameter calibration was proposed and model of the intersection of Huangcun west street and Xinghua street in Beijing was built in VISSIM to verify it. The sensitivity analysis between each check index and simulation parameter in their own set was conducted respectively. Sensitive parameter sets of different check indices were obtained and compared. The results show that different indexes have different size of set, and average vehicle delay's is maximum, so it's necessary to select index quantitatively. The results can provide references for scientific selection of the check indexes and improve the study efficiency of parameter calibration.

Meriel Talbot and the Society for the Overseas Settlement of British Women, 1919–1937

2017 ◽  
Vol 10 (1) ◽  
pp. 32-52
Author(s):  
Bonnie White
Keyword(s):  
Domestic Service ◽  
Agricultural Workers ◽  
British Government ◽  
Early Failure ◽  
Proper Selection ◽  
Domestic Servants ◽  
Female Workers ◽  
Female Migrants ◽  
Post War ◽  
Selection Of

In 1917 the British government began making plans for post-war adjustments to the economy, which included the migration of surplus women to the dominions. The Society for the Overseas Settlement of British Women was established in 1920 to facilitate the migration of female workers to the dominions. Earlier studies have argued that overseas emigration efforts purposefully directed women into domestic service as surplus commodities, thus alleviating the female ‘surplus’ and easing economic hardships of the post-war period. This article argues that as Publicity Officer for the SOSBW, Meriel Talbot targeted women she believed would be ideal candidates for emigration, including former members of the Women's Land Army and affiliated groups. With the proper selection of female migrants, Talbot sought to expand work opportunities for women in the dominions beyond domestic service, while reducing the female surplus at home and servicing the connection between state and empire. Dominion authorities, whose demands for migrant labour vacillated between agricultural workers during the war years and domestic servants after 1920, disapproved of Talbot's efforts to migrate women for work in agriculture. Divergent policies led to the early failure of the SOSBW in 1923.

Stochastic simulation for determining the design flood of cascade reservoir systems

2012 ◽  
Vol 43 (1-2) ◽  
pp. 54-63 ◽  
Author(s):  
Baohong Lu ◽  
Huanghe Gu ◽  
Ziyin Xie ◽  
Jiufu Liu ◽  
Lejun Ma ◽  
...  
Keyword(s):  
Simulation Model ◽  
Stochastic Simulation ◽  
Southern China ◽  
Flow Simulation ◽  
Simulation Method ◽  
Simulation Approach ◽  
Design Flood ◽  
Design Values ◽  
Stochastic Simulation Model ◽  
The Impact

Stochastic simulation is widely applied for estimating the design flood of various hydrosystems. The design flood at a reservoir site should consider the impact of upstream reservoirs, along with any development of hydropower. This paper investigates and applies a stochastic simulation approach for determining the design flood of a complex cascade of reservoirs in the Longtan watershed, southern China. The magnitude of the design flood when the impact of the upstream reservoirs is considered is less than that without considering them. In particular, the stochastic simulation model takes into account both systematic and historical flood records. As the reliability of the frequency analysis increases with more representative samples, it is desirable to incorporate historical flood records, if available, into the stochastic simulation model. This study shows that the design values from the stochastic simulation method with historical flood records are higher than those without historical flood records. The paper demonstrates the advantages of adopting a stochastic flow simulation approach to address design-flood-related issues for a complex cascade reservoir system.

scholarly journals Design Concepts for NiTiNOL Wires to Function as a Sensor

2021 ◽  
Author(s):  
D. Josephine Selvarani Ruth
Keyword(s):  
Shape Memory Alloy ◽  
Electrical Resistance ◽  
Nickel Titanium ◽  
The Other ◽  
Sensing Element ◽  
Proper Selection ◽  
Design Concepts ◽  
Mechanical Element ◽  
Selection Of ◽  
Inverse Hysteresis

AbstractNickel Titanium Naval Ordinance Laboratory (NiTiNOL) is widely called as a shape memory alloy (SMA), a class of nonlinear smart material inherited with the functionally programmed property of varying electrical resistance during the transformation enabling to be positioned as a sensing element. The major challenge to instrument the SMA wires is to suppress the wires’ nonlinearity by proper selection of two important factors. The first factor is influenced by the mechanical biasing element and the other is to identify the sensing current for the sensing device (SMA wires + biasing). This paper focuses on developing SMA wires for sensing in different orientation types and configurations by removing the non-linearity in the system’s output by introducing inverse hysteresis to the wires through the passive mechanical element.

A Non-Normality Measure of the Condition Number for Monitoring and Control

1997 ◽  
Vol 119 (2) ◽  
pp. 217-222 ◽  
Author(s):  
Kunsoo Huh ◽  
Jeffrey L. Stein
Keyword(s):  
Optimal Control ◽  
Condition Number ◽  
Minimization Problem ◽  
Monitoring And Control ◽  
Proper Selection ◽  
Modal Structure ◽  
L2 Norm ◽  
And Control ◽  
Normality Measure ◽  
Selection Of

Because the behavior of the condition number can have highly steep and multi-modal structure, optimal control and monitoring problems based on the condition number cannot be easily solved. In this paper, a minimization problem is formulated for κ2(P), the condition number of an eigensystem (P) of a matrix in terms of the L2 norm. A new non-normality measure is shown to exist that guarantees small values for the condition number. In addition, this measure can be minimized by proper selection of controller and observer gains. Application to the design of well-conditioned controller and observer-based monitors is illustrated.

scholarly journals The impact of the health condition of oaks from the Krotoszyn Plateau on the mechanical properties of timber structures

2015 ◽  
Vol 57 (4) ◽  
pp. 224-232
Author(s):  
Jarosław Siwiński ◽  
Katarzyna Kubiak ◽  
Miłosz Tkaczyk ◽  
Anna Mazur ◽  
Ryszard Rekucki
Keyword(s):  
Mechanical Properties ◽  
Health Condition ◽  
Health State ◽  
Timber Structures ◽  
Strength Parameters ◽  
Modified Method ◽  
Strength Tests ◽  
Prior Selection ◽  
The Impact ◽  
Selection Of

Abstract The study was conducted to perform a comparative analysis of the mechanical properties of wood samples derived from oaks in the Krotoszyn Plateau, which depend on the health state of the trees. Strength parameters of oak wood were calculated for selected diseased and healthy trees (according to the Roloff classification). The study was conducted by a modified method described in the standard Polish Norm PN EN 408+ A1: 2012. For testing, prior selection of wood samples showed that more wood samples of diseased trees compared with those of healthy oaks did not fulfil the Polish standard requirements. According to the method used, the average results of strength tests of timber structures from healthy oaks exhibited higher strength parameters than those of the diseased trees.

scholarly journals Influence of the Chemical Composition on Electrical Conductivity and Mechanical Properties of the Hypoeutectic Al-Si-Mg Alloys

2016 ◽  
Vol 61 (1) ◽  
pp. 353-360 ◽  
Author(s):  
B. Dybowski ◽  
J. Szymszal ◽  
Ł. Poloczek ◽  
A. Kiełbus
Keyword(s):  
Mechanical Properties ◽  
Electrical Conductivity ◽  
Chemical Composition ◽  
Aluminium Alloys ◽  
Mg Alloys ◽  
High Electrical Conductivity ◽  
Transportation Industry ◽  
Proper Selection ◽  
Ti Addition ◽  
Selection Of

Due to low density and good mechanical properties, aluminium alloys are widely applied in transportation industry. Moreover, they are characterized by the specific physical properties, such as high electrical conductivity. This led to application of the hypoeutectic Al-Si-Mg alloys in the power generation industry. Proper selection of the alloys chemical composition is an important stage in achievement of the demanded properties. The following paper presents results of the research on the influence of alloys chemical composition on their properties. It has been revealed that Si and Ti addition decreases electrical conductivity of the Al-Si-Mg alloys, while Na addition increases it. The mechanical properties of the investigated alloys are decreased by both silicon and iron presence. Sodium addition increases ductility of the Al-Si-Mg alloys.

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