Failure Surface Frontier for Reliability Assessment on Expensive Performance Function

2006 ◽  
Vol 128 (6) ◽  
pp. 1227-1235 ◽  
Author(s):  
Songqing Shan ◽  
G. Gary Wang
Keyword(s):  
State Of The Art ◽  
Reliability Assessment ◽  
Failure Surface ◽  
Test Results ◽  
Approximation Model ◽  
Limit States ◽  
Performance Function ◽  
Failure Region ◽  
Novel Concept ◽  
Quadratic Approximations

This work proposes a novel concept of failure surface frontier (FSF), which is a hyper-surface consisting of the set of non-dominated failure points on the limit states of a failure region. Assumptions, definitions, and benefits of FSF are described first in detail. It is believed that FSF better represents the limit states for reliability assessment (RA) than conventional linear or quadratic approximations on the most probable point. Then, a discriminative sampling based algorithm is proposed to identify FSF, based on which the reliability can be directly assessed for expensive performance functions. Though an approximation model is employed to approximate the limit states, it is only used as a guide for sampling and a supplementary tool for RA. Test results on well-known problems show that FSF-based RA on expensive performance functions achieves high accuracy and efficiency, when compared with the state-of-the-art results archived in literature. Moreover, the concept of FSF and proposed RA algorithm are proved to be applicable to problems of multiple failure regions, multiple most probable points, or failure regions of extremely small probability.

Reliability Assessment Based on the Concept of Failure Surface Frontier

2005 ◽  
Author(s):  
Songqing Shan ◽  
G. Gary Wang
Keyword(s):  
High Efficiency ◽  
Limit State ◽  
Reliability Assessment ◽  
Failure Surface ◽  
Test Results ◽  
Limit States ◽  
Failure Region ◽  
Novel Concept ◽  
Quadratic Approximations ◽  
State Functions

This work proposes a novel concept of failure surface frontier (FSF), which is a hyper-surface consisting of the set of the non-dominated failure points on the limit states of a given failure region. FSF better represents the limit state functions for reliability assessment than conventional linear or quadratic approximations on the most probable point (MPP). Assumptions, definitions, and benefits of FSF are discussed first in detail. Then, a discriminative sampling based algorithm was proposed to identify FSF, from which reliability is assessed. Test results on well known problems show that reliability can be accurately estimated with high efficiency. The algorithm is also effective for problems of multiple failure regions, multiple most probable points (MPP), or failure regions of extremely small probability.

An Integrated Performance Measure Approach for System Reliability Assessment

2014 ◽  
Author(s):  
Zequn Wang ◽  
Pingfeng Wang
Keyword(s):  
System Reliability ◽  
Limit State ◽  
Reliability Assessment ◽  
Failure Surface ◽  
Performance Measure ◽  
State Function ◽  
Analysis Tool ◽  
Performance Measure Approach ◽  
Performance Function ◽  
Integrated Performance

This paper presents an integrated performance measure approach (iPMA) for system reliability assessment considering multiple dependent failure modes. An integrated performance function is developed to envelope all component level failure events, thereby enables system reliability approximation by considering only one integrated system limit state. The developed integrated performance function possesses two critical properties. First, it represents exact joint failure surface defined by multiple component failure events, thus no error will be induced due to the integrated limit state function in system reliability computation. Second, smoothness of the integrated performance on system failure surface can be guaranteed, therefore advanced response surface techniques can be conveniently employed for response approximation. With the developed integrated performance function, the maximum confidence enhancement based sequential sampling method is adopted as an efficient component reliability analysis tool for system reliability approximation. To furthermore improve the computational efficiency, a new constraint filtering technique is developed to adaptively identify active limit states during the iterative sampling process without inducing any extra computational cost. One case study is used to demonstrate the effectiveness of system reliability assessment using the developed iPMA methodology.

A Radial-Based Centralized Kriging Method for System Reliability Assessment

2018 ◽  
Vol 140 (7) ◽  
Author(s):  
Yao Wang ◽  
Dongpao Hong ◽  
Xiaodong Ma ◽  
Hairui Zhang
Keyword(s):  
System Reliability ◽  
High Efficiency ◽  
Reliability Assessment ◽  
System Failure ◽  
Kriging Method ◽  
Limit States ◽  
Density Region ◽  
High Probability Density ◽  
Failure Region ◽  
Computationally Intensive

System reliability assessment is a challenging task when using computationally intensive models. In this work, a radial-based centralized Kriging method (RCKM) is proposed for achieving high efficiency and accuracy. The method contains two components: Kriging-based system most probable point (MPP) search and radial-based centralized sampling. The former searches for the system MPP by progressively updating Kriging models regardless of the nonlinearity of the performance functions. The latter refines the Kriging models with the training points (TPs) collected from pregenerated samples. It concentrates the sampling in the important high-probability density region. Both components utilize a composite criterion to identify the critical Kriging models for system failure. The final Kriging models are sufficiently accurate only at those sections of the limit states that bound the system failure region. Its efficiency and accuracy are demonstrated via application to three examples.

Experiences in Field Testing a Variety of Aeration Equipment in Sweden and in the U.S.A. by Offgas Analysis

1989 ◽  
Vol 21 (10-11) ◽  
pp. 1421-1429
Author(s):  
D. T. Redmon ◽  
W. C. Boyle ◽  
B. G. Hellstrom
Keyword(s):  
Oxygen Transfer ◽  
State Of The Art ◽  
Field Testing ◽  
Analysis Procedure ◽  
Test Results ◽  
Transfer Testing ◽  
Parallel Tests

The background and theory of the offgas analysis procedure used in oxygen transfer testing of diffused aeration tanks is reviewed. Correlation of this method with other applicable procedures in parallel tests is reported. State-of-the-art equipment and accessories are described. Advantages of the procedure are identified, as are precautionary considerations regarding its use. Applications considered appropriate for its employment are delineated. Experience and test results in both Sweden and the U.S.A. on a variety of aeration devices are disclosed.

scholarly journals Finding the Perfect Match: Different Heavy-Duty Mobile Applications Call for Different Actuators

Proceedings ◽  
2020 ◽  
Vol 64 (1) ◽  
pp. 22
Author(s):  
David Fassbender ◽  
Tatina Minav
Keyword(s):  
Mobile Applications ◽  
State Of The Art ◽  
Perfect Match ◽  
The Novel ◽  
Hydraulic Systems ◽  
Heavy Duty ◽  
Different Types ◽  
Evaluation Algorithm ◽  
Novel Concept ◽  
Valve Control

For the longest time, valve-controlled, centralized hydraulic systems have been the state-of-the-art technology to actuate heavy-duty mobile machine (HDMM) implements. Due to the typically low energy efficiency of those systems, a high number of promising, more-efficient actuator concepts has been proposed by academia as well as industry over the last decades as potential replacements for valve control—e.g., independent metering, displacement control, different types of electro-hydraulic actuators (EHAs), electro-mechanic actuators, or hydraulic transformers. This paper takes a closer look on specific HDMM applications for these actuator concepts to figure out where which novel concept can be a better alternative to conventional actuator concepts, and where novel concepts might fail to improve. For this purpose, a novel evaluation algorithm for actuator–HDMM matches is developed based on problem aspects that can indicate an unsuitable actuator–HDMM match. To demonstrate the functionality of the match evaluation algorithm, four actuator concepts and four HDMM types are analyzed and rated in order to form 16 potential actuator–HDMM matches that can be evaluated by the novel algorithm. The four actuator concepts comprise a conventional valve-controlled concept and three different types of EHAs. The HDMM types are excavator, wheel loader, backhoe, and telehandler. Finally, the evaluation of the 16 matches results in 16 mismatch values, of which the lowest indicates the “perfect match”. Low mismatch values could be found in general for EHAs in combination with most HDMMs but also for a valve-controlled actuator concept in combination with a backhoe. Furthermore, an analysis of the concept limitations with suggestions for improvement is included.

scholarly journals A Review on the Performance and Comfort of Stab Protection Armor

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Dereje Berihun Sitotaw ◽  
Dustin Ahrendt ◽  
Yordan Kyosev ◽  
Abera Kechi Kabish
Keyword(s):  
Protective Clothing ◽  
State Of The Art ◽  
Upper Body ◽  
Test Results ◽  
Safety Equipment ◽  
Freedom Of Movement ◽  
Prototype Test ◽  
Wear Comfort ◽  
Correction Officers ◽  
Security Control

Abstract Stab-protective clothing is the most important component of safety equipment and it helps to save the lives of its wearers; therefore, it is designed to resist knife, nail, or needle attacks, especially to the upper body. In this paper, the essential requirements for stab-resistant armor are investigated based on an in-depth review of previous research and prototype test results. The combination of protection and comfort in armor vests is a particularly challenging task. Review of the state of the art technology responsible for the manufacture of stab-resistant clothes has revealed that their design and development should encompass the elements of comfort, freedom of movement, permeability, absorption, evaporation, and weight reductions to ensure excellent ergonomics and high wear comfort. The design as well as the production, weight, thickness, material types and properties, and the arrangement of scales determine the level of protection and comfort offered by stab-resistant vests. Currently, the production of stab-proof gear-based 3D printing technology is evaluated, using lightweight materials (aramid) in the form of segmented scales inspired by nature. As the protection performance and wear comfort of stab-proof gear is enhanced, the willingness of security, control, transport, custom, and correction officers to wear them can be significantly increased in an endeavor to ensure that fatal injuries will decrease significantly.

The Art and Science of Rotary Wing Data Correlation

1976 ◽  
Vol 21 (3) ◽  
pp. 2-12
Author(s):  
Jan M. Drees
Keyword(s):  
Wind Tunnel ◽  
Test Data ◽  
State Of The Art ◽  
Helicopter Rotor ◽  
Small Scale ◽  
Test Results ◽  
Free Flight ◽  
Full Scale Tests ◽  
Rotary Wing ◽  
Theoretical Analyses

This paper presents an overview of the correlation of helicopter rotor performance and loads data from various tests and analyses. Information is included from U.S. Army‐sponsored tests conducted by Bell Helicopter Company for free‐flight full‐scale tests in the NASA‐Ames 40 × 80 wind tunnel, one‐fifth scale tests in the NASA‐Langley Transonic Dynamics Tunnel, and small‐scale tests of a rotor in air. These test data are compared with each other, where appropriate, and with calculated results. Typical examples illustrate the state of the art for correlation and indicate anomalies encountered. It is concluded that a procedure using theoretical analyses to aid in interpretation and evaluation of test results is essential to developing a science of correlation.

A novel measurement strategy to evaluate the human head as a transition medium for inductive ear-to-ear communication

2019 ◽  
Vol 64 (2) ◽  
pp. 233-241
Author(s):  
Jan-Christoph Edelmann ◽  
Dominik Mair ◽  
Thomas Ussmueller
Keyword(s):  
Low Power ◽  
Hearing Aids ◽  
State Of The Art ◽  
Near Field ◽  
Human Head ◽  
International Telecommunication Union ◽  
International Telecommunication ◽  
Channel Characteristics ◽  
Coupling Factors ◽  
Novel Concept

Abstract This manuscript introduces a novel concept for measuring coil coupling for extremely loose-coupled coils (coupling factors k<10−6; mutual inductance values M<10−10 H). Such a coupling is found everywhere where the ratio of solenoid diameter to coil spacing is >50. Measuring these quantities with a low-power technology requires a sophisticated setup that goes beyond the sensitivity of state-of-the art approaches. The methodology is validated using laboratory measurements with three sets of solenoids (two ferrite-cored, one air-cored) and numerical simulations with COMSOL Multiphysics 5.2a, Stockholm, Sweden. The concept is then employed to investigate the channel characteristics for inductive through-the-head communication within the 3.155–3.195 MHz band. This selected part of the spectrum is in accordance with International Telecommunication Union Radio Regulation 5.116 for low-power wireless hearing aids. By applying a phantom solution, we demonstrate that human tissue layers are transparent for magnetic fields within these frequencies. However, the influence from the relative coil arrangement is evaluated in detail as it restricts the communication range significantly. The coupling results for off-the-shelf Sonion, Roskilde, Denmark, RF 02 AA 10 solenoids considering both lateral and axial displacements might be of special interest for a number of near-field applications.

Introduction and Commissioning of the New Darmstadt Transonic Compressor Test Facility

2019 ◽  
Author(s):  
Christian Kunkel ◽  
Jan Werner ◽  
Daniel Franke ◽  
Heinz-Peter Schiffer ◽  
Fabian Wartzek ◽  
...  
Keyword(s):  
Control Systems ◽  
Gas Turbines ◽  
State Of The Art ◽  
Test Facility ◽  
Test Results ◽  
Test Rig ◽  
Vast Number ◽  
Transonic Compressor ◽  
Profound Knowledge ◽  
And Control

Abstract With the well-known Transonic Compressor Darmstadt (TCD) in operation since 1994, profound knowledge in designing and operating a sophisticated test-rig is available at the Institute of Gas Turbines and Aerospace Propulsion of TU Darmstadt. During this period, TCD has been subject to a vast number of redesigns within different measurement campaigns (see [1], [2], [3], [4], [5], [6], [7], [8]). To expand the capabilities and ensure a sustainable process of compressor research, a new test facility was designed and built by the institute. The new test rig Transonic Compressor Darmstadt 2 (TCD2) features increased power for higher pressure ratios and higher mass-flow, a state of the art control system, increased flexibility towards different compressor geometries and modern data acquisition hardware and software. Following the successful commissioning of the test-rig in March 2018, a first measurement campaign has been conducted. Early test results regarding aerodynamic performance and aeroelastic effects of the test compressor are presented together with a detailed overview of test-rig infrastructure and control systems as well as the test compressor and the measurement hardware.

scholarly journals Gate-tunable graphene-based Hall sensors on flexible substrates with increased sensitivity

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Burkay Uzlu ◽  
Zhenxing Wang ◽  
Sebastian Lukas ◽  
Martin Otto ◽  
Max C. Lemme ◽  
...  
Keyword(s):  
Magnetic Field ◽  
State Of The Art ◽  
Signal To Noise Ratio ◽  
Flexible Substrates ◽  
Static Case ◽  
Static Operation ◽  
Increased Sensitivity ◽  
Novel Concept ◽  
Hall Sensors ◽  
P Type

AbstractWe demonstrate a novel concept for operating graphene-based Hall sensors using an alternating current (AC) modulated gate voltage, which provides three important advantages compared to Hall sensors under static operation: (1) The sensor sensitivity can be doubled by utilizing both n- and p-type conductance. (2) A static magnetic field can be read out at frequencies in the kHz range, where the 1/f noise is lower compared to the static case. (3) The off-set voltage in the Hall signal can be reduced. This significantly increases the signal-to-noise ratio compared to Hall sensors without a gate electrode. A minimal detectable magnetic field Bmin down to $$290\,{\rm{nT}}/\surd {\rm{Hz}}$$290nT/√Hz and sensitivity up to 0.55 V/VT was found for Hall sensors working on flexible polyimide (PI) substrates. This clearly outperforms state-of-the-art flexible Hall sensors and is comparable to the values obtained by the best rigid III/V semiconductor Hall sensors.

Sign in / Sign up

Export Citation Format

Share Document