scholarly journals Dynamic model substantiation of elastic body in bilevel car

2015 ◽  
Vol 2015 (4) ◽  
pp. 50-53
Author(s):  
Владимир Лебедев ◽  
Vladimir Lebedev ◽  
Дмитрий Антипин ◽  
Dmitriy Antipin ◽  
Владимир Кобищанов ◽  
...  
Keyword(s):  
Element Model ◽  
Test Subject ◽  
Test Results ◽  
Bending Vibrations ◽  
Car Body ◽  
Vibration Tests ◽  
Definition Of ◽  
Mass Position ◽  
Use Of Models ◽  
Actual Test

The aim of this work consists in choosing a rational way for the definition of selfresonant frequency in car body bending vibrations of a bilevel car. A test subject is the car body of a bilevel car of the model 61-4465 manufactured by the Company «Tver Wagon Works». The vibration tests of a bilevel car were modeled. Test results were compared to the data of actual test and a computation on the recommendations of regulations. There is developed a lamellar finite-element model of a bilevel car carcass with its stiffness corresponding to a real car body. The assessment of selfresonant frequency in car body bending vibrations was carried out on basis of three variants of its model differed with the distribution of car body gross weight: uniformly throughout the whole of metalware; throughout the parts of metalware in accordance with mass position in a real car; taking into account the influence of partition rigidity in compartments and service rooms. The comparison of modeling results with the use of models described and results of actual tests shows their satisfactory correspondence that allows approaching to dynamic values of a real car body at the investigation of its loading by the methods of computer simulation.

CALCULATION-EXPERIMENTAL METHOD FOR DEFINITION OF LOWEST FREQUENCY IN BENDING VIBRATIONS OF COACH CAR BODY IN VERTICAL PLANE BASED ON IDENTIFICATION OF ITS BENDING STIFFNESS

2020 ◽  
Vol 2020 (9) ◽  
pp. 35-46
Author(s):  
Aleksandr Skachkov ◽  
Viktor Vasilevskiy ◽  
Aleksey Yuhnevskiy
Keyword(s):  
Least Squares Method ◽  
Vertical Plane ◽  
Bending Stiffness ◽  
Dimensional Problem ◽  
Euler Beam ◽  
Bending Vibrations ◽  
Car Body ◽  
Variable Function ◽  
Experimental Values ◽  
Definition Of

The consideration of existing methods for a modal analysis has shown a possibility for the lowest frequency definition of bending vibrations in a coach car body in a vertical plane based on an indirect method reduced to the assessment of the bending stiffness of the one-dimensional model as a Bernoulli-Euler beam with fragment-constant parameters. The assessment mentioned can be obtained by means of the comparison of model deflections (rated) and a prototype (measured experimentally upon a natural body) with the use of the least-squares method that results in the necessity of the solution of the multi-dimensional problem with the reverse coefficient. The introduction of the hypothesis on ratability of real bending stiffness of the prototype and easily calculated geometrical stiffness of a model reduces a multi-dimensional problem incorrect according to Adamar to the simplest search of the extremum of one variable function. The procedure offered for the indirect assessment of bending stiffness was checked through the solution of model problems. The values obtained are offered to use for the assessment of the lowest frequency of bending vibrations with the aid of Ritz and Grammel methods. In case of rigid poles it results in formulae for frequencies into which there are included directly the experimental values of deflections.

CALCULATION-EXPERIMENTAL METHOD FOR DEFINITION OF LOWEST FREQUENCY IN BENDING VIBRATIONS OF COACH CAR BODY IN VERTICAL PLANE BASED ON IDENTIFICATION OF ITS BENDING STIFFNESS

2020 ◽  
Vol 2020 (9) ◽  
pp. 35-46
Author(s):  
Aleksandr Skachkov ◽  
Viktor Vasilevskiy ◽  
Aleksey Yuhnevskiy
Keyword(s):  
Least Squares Method ◽  
Vertical Plane ◽  
Bending Stiffness ◽  
Dimensional Problem ◽  
Euler Beam ◽  
Bending Vibrations ◽  
Car Body ◽  
Variable Function ◽  
Experimental Values ◽  
Definition Of

The consideration of existing methods for a modal analysis has shown a possibility for the lowest frequency definition of bending vibrations in a coach car body in a vertical plane based on an indirect method reduced to the assessment of the bending stiffness of the one-dimensional model as a Bernoulli-Euler beam with fragment-constant parameters. The assessment mentioned can be obtained by means of the comparison of model deflections (rated) and a prototype (measured experimentally upon a natural body) with the use of the least-squares method that results in the necessity of the solution of the multi-dimensional problem with the reverse coefficient. The introduction of the hypothesis on ratability of real bending stiffness of the prototype and easily calculated geometrical stiffness of a model reduces a multi-dimensional problem incorrect according to Adamar to the simplest search of the extremum of one variable function. The procedure offered for the indirect assessment of bending stiffness was checked through the solution of model problems. The values obtained are offered to use for the assessment of the lowest frequency of bending vibrations with the aid of Ritz and Grammel methods. In case of rigid poles it results in formulae for frequencies into which there are included directly the experimental values of deflections.

scholarly journals Haemostatic and thrombo-embolic complications in pregnant women with COVID-19: a systematic review and critical analysis

2021 ◽  
Vol 21 (1) ◽  
Author(s):  
Juliette Servante ◽  
Gill Swallow ◽  
Jim G. Thornton ◽  
Bethan Myers ◽  
Sandhya Munireddy ◽  
...  
Keyword(s):  
Venous Thrombosis ◽  
Pregnant Women ◽  
Clinical Evidence ◽  
Case Reports ◽  
Standard Form ◽  
Test Results ◽  
Maternal Deaths ◽  
High Clinical Suspicion ◽  
Increased Risk ◽  
Definition Of

Abstract Background As pregnancy is a physiological prothrombotic state, pregnant women may be at increased risk of developing coagulopathic and/or thromboembolic complications associated with COVID-19. Methods Two biomedical databases were searched between September 2019 and June 2020 for case reports and series of pregnant women with a diagnosis of COVID-19 based either on a positive swab or high clinical suspicion where no swab had been performed. Additional registry cases known to the authors were included. Steps were taken to minimise duplicate patients. Information on coagulopathy based on abnormal coagulation test results or clinical evidence of disseminated intravascular coagulation (DIC), and on arterial or venous thrombosis, were extracted using a standard form. If available, detailed laboratory results and information on maternal outcomes were analysed. Results One thousand sixty-three women met the inclusion criteria, of which three (0.28, 95% CI 0.0 to 0.6) had arterial and/or venous thrombosis, seven (0.66, 95% CI 0.17 to 1.1) had DIC, and a further three (0.28, 95% CI 0.0 to 0.6) had coagulopathy without meeting the definition of DIC. Five hundred and thirty-seven women (56%) had been reported as having given birth and 426 (40%) as having an ongoing pregnancy. There were 17 (1.6, 95% CI 0.85 to 2.3) maternal deaths in which DIC was reported as a factor in two. Conclusions Our data suggests that coagulopathy and thromboembolism are both increased in pregnancies affected by COVID-19. Detection of the former may be useful in the identification of women at risk of deterioration.

scholarly journals Experimental and Numerical Investigation on the Steel Reinforced Grout (SRG) Composite-to-Concrete Bond

2020 ◽  
Vol 4 (4) ◽  
pp. 182
Author(s):  
Luciano Ombres ◽  
Salvatore Verre
Keyword(s):  
Bond Length ◽  
Failure Modes ◽  
Peak Load ◽  
Element Model ◽  
Test Results ◽  
Shear Tests ◽  
Bond Slip ◽  
Bond Behavior ◽  
Direct Shear Tests ◽  
Inorganic Matrix

In the paper, the bond between a composite strengthening system consisting of steel textiles embedded into an inorganic matrix (steel reinforced grout, SRG) and the concrete substrate, is investigated. An experimental investigation was carried out on medium density SRG specimens; direct shear tests were conducted on 20 specimens to analyze the effect of the bond length, and the age of the composite strip on the SRG-to-concrete bond behavior. In particular, the tests were conducted considering five bond length (100, 200, 250, 330, and 450 mm), and the composite strip’s age 14th, 21st, and 28th day after the bonding. Test results in the form of peak load, failure modes and, bond-slip diagrams were presented and discussed. A finite element model developed through commercial software to replicate the behavior of SRG strips, is also proposed. The effectiveness of the proposed numerical model was validated by the comparison between its predictions and experimental results.

Design of Static Test Model for Three-Tower Cable-Stayed Self-Anchored Suspension Composed Bridge

2011 ◽  
Vol 243-249 ◽  
pp. 1528-1535
Author(s):  
Yu Zhao ◽  
Yong Jun Zhou ◽  
Jing Sun ◽  
Jin Tao Tang ◽  
Xu Li
Keyword(s):  
Complex System ◽  
Finite Element ◽  
Element Model ◽  
Test Model ◽  
Test Results ◽  
Static Test ◽  
Whole Process ◽  
Aesthetic Appearance ◽  
Load Carrying ◽  
Novel Structures

Cable-stayed self-anchored suspension composed bridges have novel structures and aesthetic appearance with complex system and difficulty for design and construction. In order to acquire a better knowledge of the load-carrying capability of this type of bridges, based on a real bridge and the theory of abnormal similarity, a full-bridge scaled down(1:20) test model was built to simulate the whole process of construction. The test results were preferably fit the theoretical calculation value. It can be seen that the design of the bridge was reasonable, and the accuracy of the calculation of finite element model was verified at the same time. The test and the related results can be used as the reference for the test and design of the similar bridges.

scholarly journals Bi-Directional Power Flow in Switchgear with Static Transfer Switch Applied at Various Renewable Energies

Energies ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3187
Author(s):  
Keon-Woo Park ◽  
Chul-Hwan Kim
Keyword(s):  
Communication System ◽  
Power Flow ◽  
Electronic Device ◽  
Test Sequence ◽  
Test Results ◽  
Distributed Generations ◽  
Prototype Development ◽  
Intelligent Electronic Device ◽  
Bidirectional Power Flow ◽  
Actual Test

In this study, we describe the development of a plug-in type of switchgear that can control bidirectional power flow. This switchgear system can connect distributed generations such as photovoltaic and wind turbine generation, and AC and DC loads. The proposed switchgear system consists of an inverter for connecting distributed generations and DC load, a static transfer switch (STS) that can control and interrupt the bidirectional power flow, and an intelligent electronic device (IED) that can control each facility using a communication system. Since the topology inside the switchgear is composed of DC bus, it can be operated as a plug-in type of system that can be used by simply connecting the converters of various distributed generations to the inverter in the developed switchgear system. In this study, we describe the overall structure of the proposed switchgear system and the operation of the components. In addition, prototypes of each facility are developed and the results of building a small testbed are presented. Finally, we verify the operation of the inverter by performing an experiment on the testbed and show that throughout a test sequence the proposed switchgear system works normally. The contributions of this study are the development of a plug-in type of switchgear for AC/DC and the actual test results presented through prototype development and testbed configuration.

The Research of IC Test Based on LTX-77 Test System

2014 ◽  
Vol 496-500 ◽  
pp. 1176-1179
Author(s):  
Li Tan ◽  
Yu Fang
Keyword(s):  
Test Object ◽  
Test System ◽  
Test Method ◽  
Test Results ◽  
Analog Ic ◽  
Test Platform ◽  
Logic Functions ◽  
Actual Test ◽  
Ic Test

LTX-77 test system is a large IC test system that is used for various kinds of analog IC, digital IC and analog digital mixed IC. It can be used to test DC parameters, AC parameters and logic functions. In the paper, the IC test platform is LTX-77 test system. IC ADC0804 was tested as the test object. The test method of IC is described in the view of actual test. The test results show that the test system is convenient and accurate, which has important practical value for IC manufacturers and users.

Perforation mechanics of UHMWPE soft ballistic sub-laminate and soft ballistic armor pack: A finite element study

2021 ◽  
pp. 089270572110420
Author(s):  
Bazle Z (Gama) Haque ◽  
John W Gillespie
Keyword(s):  
Finite Element ◽  
Single Layer ◽  
Areal Density ◽  
Element Model ◽  
Transverse Impact ◽  
Free Standing ◽  
Uhmwpe Fibers ◽  
Ballistic Limit Velocity ◽  
Definition Of ◽  
First Time

Soft-ballistic sub-laminate (SBSL) made from ultra-high molecular weight polyethylene (UHMWPE) fibers in [0/90] stacking sequence are the building block of a multi-layer soft-ballistic armor pack (SBAP, aka Soft Armor). A systematic study of the perforation dynamics of a single layer SBSL and several multi-layer SBAPs (2, 3, 4, 8, 16, 24, 32 layers) is presented for the first time in the literature. A previously validated finite element model of transverse impact on a single layer is used to study the perforation mechanics of multi-layer SBAPs with friction between individual layers. Following the classical definition of ballistic limit velocity, a minimum perforation velocity has been determined for free-standing single layer SBSL and multi-layer SBAPs. For the multi-layer SBAPs, complete perforations have been identified as progressive perforation of individual layers through the thickness. The minimum perforation velocities of multi-layer SBAPS is linear with the areal density for the eight (8) layer target and thicker. Large deformation behavior and perforation mechanics of the SBAPs is discussed in detail.

Reporting altered test results in hemolyzed samples: is the cure worse than the disease?

2017 ◽  
Vol 55 (8) ◽  
pp. 1112-1114 ◽  
Author(s):  
Giuseppe Lippi ◽  
Gianfranco Cervellin ◽  
Mario Plebani
Keyword(s):  
Laboratory Data ◽  
Turnaround Time ◽  
Reliable Data ◽  
Test Results ◽  
The Past ◽  
Laboratory Test Results ◽  
Performance Specifications ◽  
Life Threatening ◽  
The Many ◽  
Definition Of

AbstractThe management of laboratory data in unsuitable (hemolyzed) samples remains an almost unresolved dilemma. Whether or not laboratory test results obtained by measuring unsuitable specimens should be made available to the clinicians has been the matter of fierce debates over the past decades. Recently, an intriguing alternative to suppressing test results and recollecting the specimen has been put forward, entailing the definition and implementation of specific algorithms that would finally allow reporting a preanalytically altered laboratory value within a specific comment about its uncertainty of measurement. This approach carries some advantages, namely the timely communication of potentially life-threatening laboratory values, but also some drawbacks. These especially include the challenging definition of validated performance specifications for hemolyzed samples, the need to producing reliable data with the lowest possible uncertainty, the short turnaround time for repeating most laboratory tests, the risk that the comments may be overlooked in short-stay and frequently overcrowded units (e.g. the emergency department), as well as the many clinical advantages of a direct communication with the physician in charge of the patient. Despite the debate remains open, we continue supporting the suggestion that suppressing data in unsuitable (hemolyzed) samples and promptly notifying the clinicians about the need to recollect the samples remains the most (clinically and analytically) safe practice.

Sign in / Sign up

Export Citation Format

Share Document