scholarly journals Simplified Vibration PSD Synthesis Method for MIL-STD-810

2020 ◽  
Vol 10 (2) ◽  
pp. 458
Author(s):  
Jin Jang ◽  
Jong-Won Park
Keyword(s):  
Fatigue Damage ◽  
Laboratory Tests ◽  
Synthesis Method ◽  
Environmental Engineering ◽  
Damage Potential ◽  
Test Standards ◽  
Test Synthesis ◽  
Us Military ◽  
Vibration Tests ◽  
Insight Into

In MIL-STD-810, the environmental engineering consideration and laboratory tests by US military, the DP (damage potential) formula is used to calculate the fatigue damage by vibration environments which is a simplified version of a FDS (fatigue damage spectrum) formula. DP, however, was originally made for comparison between different test standards and is not an optimized formula for the synthesis of vibration environments. This paper presents the GRS (Gaussian Random Synthesis) formula for only vibration test synthesis featuring simplified DP formula and produce the same result as DP. Although the GRS provides insight into the synthesis of vibration tests, it must be used with care because it inherits the constraints of the original FDS formula.

Antibacterial and Anti-Biofilm Biosynthesised Silver and Gold Nanoparticles for Medical Applications: Mechanism of Action, Toxicity and Current Status

2020 ◽  
Vol 17 (2) ◽  
pp. 88-100 ◽  
Author(s):  
Sundos Suleman Ismail Abdalla ◽  
Haliza Katas ◽  
Fazren Azmi ◽  
Mohd Fauzi Mh Busra
Keyword(s):  
Gold Nanoparticles ◽  
Synthesis Method ◽  
Chemical Characterization ◽  
Current Status ◽  
Silver And Gold Nanoparticles ◽  
Physical And Chemical Characterization ◽  
Biosynthesized Agnps ◽  
Physical And Chemical ◽  
Insight Into ◽  
Bio Synthesis

Fast progress in nanoscience and nanotechnology has contributed to the way in which people diagnose, combat, and overcome various diseases differently from the conventional methods. Metal nanoparticles, mainly silver and gold nanoparticles (AgNPs and AuNPs, respectively), are currently developed for many applications in the medical and pharmaceutical area including as antibacterial, antibiofilm as well as anti-leshmanial agents, drug delivery systems, diagnostics tools, as well as being included in personal care products and cosmetics. In this review, the preparation of AgNPs and AuNPs using different methods is discussed, particularly the green or bio- synthesis method as well as common methods used for their physical and chemical characterization. In addition, the mechanisms of the antimicrobial and anti-biofilm activity of AgNPs and AuNPs are discussed, along with the toxicity of both nanoparticles. The review will provide insight into the potential of biosynthesized AgNPs and AuNPs as antimicrobial nanomaterial agents for future use.

Hydrodynamic Coefficients for Riser In-Line VIV in Sheared Currents

2007 ◽  
Author(s):  
Djoni E. Sidarta ◽  
Kostas F. Lambrakos ◽  
Carl M. Larsen
Keyword(s):  
Fatigue Damage ◽  
Laboratory Tests ◽  
Ad Hoc ◽  
Science And Technology ◽  
Cross Flow ◽  
Hydrodynamic Coefficients ◽  
Simply Supported ◽  
Hydrodynamic Damping ◽  
Uniform Current ◽  
Mode Response

A methodology for analyzing risers for in-line VIV fatigue damage has been developed that is based on the code SHEAR7, and laboratory in-line VIV coefficients. The in-line VIV fatigue in many instances governs the design of the riser since in-line VIV starts at a reduced velocity of about 1 whereas the threshold reduced velocity for cross flow VIV is about 4. The methodology can treat sheared currents on the basis of the cross flow VIV modeling in SHEAR7. Through the SHEAR7 modeling, the methodology removes conservatism implicit in the present ad hoc procedures for calculating riser in-line VIV response on the basis of the DNV-RP-F105 code. The reduction in conservatism is due to accounting properly for the power-in region in the VIV excitation, the hydrodynamic damping, and competing modal excitation (multiple mode response). The inline VIV coefficients have been derived from laboratory tests at the Norwegian University of Science and Technology (NTNU). The paper presents the in-line VIV coefficients, and examples to demonstrate the methodology for riser in sheared currents. The coefficients derived from the NTNU tests are functions of both the in-line VIV response amplitude and the reduced velocity. The coefficients presented in the paper are scaled test coefficients. The scaling of the NTNU coefficients assures that the methodology calculates in-line VIV amplitudes that are consistent with the response amplitudes in DNV-RP-F105 for the case of a simply supported riser in uniform current. This DNV code, although written for pipelines, has been extended to risers in sheared currents on the basis of conservative approaches.

The Myth of Triumphalism

2019 ◽  
Author(s):  
Beth A. Fischer
Keyword(s):  
Cold War ◽  
Ronald Reagan ◽  
Moral Leadership ◽  
Nuclear Disarmament ◽  
Mikhail Gorbachev ◽  
Us Military ◽  
New Ideas ◽  
The Cold War ◽  
The Impact ◽  
Insight Into

Virtually no one anticipated the ending of the Cold War. Understanding how this long-standing conflict was peacefully resolved can give us insight into how to conclude other seemingly intractable conflicts. Triumphalists believe that President Ronald Reagan “won” the Cold War by building up US military power and threatening the USSR. His hard-line policies forced Moscow to reduce its arsenal, adopt democratic reforms, withdraw from its war in Afghanistan, and ultimately collapse. Triumphalists assert that contemporary leaders should follow Reagan’s example bycompelling adversaries into submission. However, triumphalism is a myth, a series of falsehoods about Reagan’s intentions, his policies, and the impact his administration had on the USSR.Drawing upon American and Soviet sources,this book demonstrates that Reagan’s initial hard-line policies brought the superpowers to the brink of war and made it more difficult for Moscow to disarm and reform. Compellence failed miserably. The Cold War was resolved through diplomacy, not threats. President Reagan eventually engaged in dialogue so as to ease Moscow’s security concerns, build trust, and focus on the superpowers’ mutual interest in eliminating nuclear arms. For his part, Mikhail Gorbachev sought to end the arms race so as to divert resources to democratization. He too sought dialogue and trust. The ending of the Cold War demonstrates the importance of moral leadership. Reagan and Gorbachev both rose above their differences and introduced radical new ideas about nuclear disarmament. Consequently, both encountered domestic opposition. Each persevered, however, leading their nations toward a safer, more humane future.

Synthesis of a Time History Based on the Sine-on-Random Prediction Methodology Defined in MIL-STD-810 Method 519

2017 ◽  
Vol 60 (1) ◽  
pp. 31-41
Author(s):  
Michael T. Hale
Keyword(s):  
Time Domain ◽  
Laboratory Tests ◽  
Field Data ◽  
Time History ◽  
Environmental Engineering ◽  
New Technique ◽  
Vibration Test ◽  
Temporal Characteristics ◽  
New Time ◽  
Exponentially Weighted

Abstract Method 519.7, Annex D of MIL-STD-810G, Environmental Engineering Considerations and Laboratory Tests, Change Notice 1 (MIL-STD-810G/CN1) outlines a prediction methodology for establishing a sine-on-random (SoR) structured spectrum that is intended to be representative of gunfire for use in cases in which there is an absence of field data. From that spectrum, the ramp modulated pulse (RMP) technique is proposed as a methodology to synthesize a time history with temporal characteristics that more realistically represent the temporal characteristics of gunfire than that of a SoR time history synthesized via classical SoR generation techniques. This paper provides an alternate technique to the RMP methodology presented in Method 519. The alternate technique is based on normalized exponentially weighted (NEW) time history generated via classical time domain techniques for a SoR vibration test. An outline of the NEW technique and an associated example are provided.

Accelerating the fatigue analysis based on strain signal using Hilbert–Huang transform

2019 ◽  
Vol 10 (1) ◽  
pp. 118-132
Author(s):  
Nadia Nurnajihah M. Nasir ◽  
Salvinder Singh ◽  
Shahrum Abdullah ◽  
Sallehuddin Mohamed Haris
Keyword(s):  
Fatigue Life ◽  
Fatigue Damage ◽  
Low Frequency ◽  
Life Assessment ◽  
Distribution Analysis ◽  
Original Signal ◽  
Damage Potential ◽  
Content Type ◽  
Hilbert Huang Transform ◽  
Time Frequency

Purpose The purpose of this paper is to present the application of Hilbert–Huang transform (HHT) for fatigue damage feature characterisation in the time–frequency domain based on strain signals obtained from the automotive coil springs. Design/methodology/approach HHT was employed to detect the temporary changes in frequency characteristics of the vibration response of the signals. The extraction successfully reduced the length of the original signal to 40 per cent, whereas the fatigue damage was retained. The analysis process for this work is divided into three stages: signal characterisation with the application of fatigue data editing (FDE) for fatigue life assessment, empirical mode decomposition with Hilbert transform, an energy–time–frequency distribution analysis of each intrinsic mode function (IMF). Findings The edited signal had a time length of 72.5 s, which was 40 per cent lower than the original signal. Both signals were retained statistically with close mean, root-mean-square and kurtosis value. FDE improved the fatigue life, and the extraction did not affect the content and behaviour of the original signal because the editing technique only removed the minimal fatigue damage potential. HHT helped to remove unnecessary noise in the recorded signals. EMD produced sets of IMFs that indicated the differences between the original signal and mean of the signal to produce new components. The low-frequency energy was expected to cause large damage, whereas the high-frequency energy will cause small damage. Originality/value HHT and EMD can be used in the strain data signal analysis of the automotive component of a suspension system. This is to improve the fatigue life, where the extraction did not affect the content and behaviour of the original signal because the editing technique only removed the minimal fatigue damage potential.

Organic Nanosynthesis of Ancient Windmill-like Window Gridarenes at Molecular Scale

2018 ◽  
Author(s):  
Ying Wei ◽  
Quanyou Feng ◽  
Hui Liu ◽  
Xiuling Wang ◽  
Dongqing Lin ◽  
...  
Keyword(s):  
Main Product ◽  
Synthesis Method ◽  
Synthetic Method ◽  
X Ray Diffraction ◽  
One Pot ◽  
X Ray ◽  
H Nmr ◽  
Cyclization Process ◽  
Molecular Scale ◽  
Insight Into

We focus on another kind of square-type unit nanogrids with starlike divergent extensibility. As a result, square windmill-like nanogrid <b>WG4</b> have been successfully synthesized by two different kinds of fluorene-based nanosynthons, namely I-shape nanosynthon and L-shape nanosynthon synthesis method. Besides <b>WG4</b>, triangle and hexagon windmill-like nanogrids (<b>WG3</b> and <b>WG5</b>) are also obtained via one-pot nanosynthesis of I-shape nanosynthon with <b>WG3</b> as the main product. For the L-shape nanosynthon synthetic method, the cyclization process possesses higher selectivity, resulting to an excellent yield for <b>WG</b>4. In addition, two stereoisomers of the triangle nanogrids, <i>cis-trans</i>-<b>WG3</b> and <i>cis-cis-</i><b>WG3</b>, were separated and characterized from the single-crystal X-ray diffraction and <sup>1</sup>H NMR analyses for getting insight into the configuration of the triangle nanogrids with the skeleton planarization for the <i>trans</i>-configuration and deplanarization for the <i>cis</i>-configuration.

Organic Nanosynthesis of Ancient Windmill-like Window Gridarenes at Molecular Scale

2018 ◽  
Author(s):  
Ying Wei ◽  
Quanyou Feng ◽  
Hui Liu ◽  
Xiuling Wang ◽  
Dongqing Lin ◽  
...  
Keyword(s):  
Main Product ◽  
Synthesis Method ◽  
Synthetic Method ◽  
X Ray Diffraction ◽  
One Pot ◽  
X Ray ◽  
H Nmr ◽  
Cyclization Process ◽  
Molecular Scale ◽  
Insight Into

We focus on another kind of square-type unit nanogrids with starlike divergent extensibility. As a result, square windmill-like nanogrid <b>WG4</b> have been successfully synthesized by two different kinds of fluorene-based nanosynthons, namely I-shape nanosynthon and L-shape nanosynthon synthesis method. Besides <b>WG4</b>, triangle and hexagon windmill-like nanogrids (<b>WG3</b> and <b>WG5</b>) are also obtained via one-pot nanosynthesis of I-shape nanosynthon with <b>WG3</b> as the main product. For the L-shape nanosynthon synthetic method, the cyclization process possesses higher selectivity, resulting to an excellent yield for <b>WG</b>4. In addition, two stereoisomers of the triangle nanogrids, <i>cis-trans</i>-<b>WG3</b> and <i>cis-cis-</i><b>WG3</b>, were separated and characterized from the single-crystal X-ray diffraction and <sup>1</sup>H NMR analyses for getting insight into the configuration of the triangle nanogrids with the skeleton planarization for the <i>trans</i>-configuration and deplanarization for the <i>cis</i>-configuration.

scholarly journals On the Shaker Simulation of Wind-Induced Non-Gaussian Random Vibration

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Fei Xu ◽  
Chuanri Li ◽  
Tongmin Jiang
Keyword(s):  
Random Vibration ◽  
Field Data ◽  
Response Spectrum ◽  
Synthesis Method ◽  
Control Mode ◽  
Damage Potential ◽  
Extreme Response ◽  
Gaussian Signal ◽  
Non Gaussian

Gaussian signal is produced by ordinary random vibration controllers to test the products in the laboratory, while the field data is usually non-Gaussian. Two methodologies are presented in this paper for shaker simulation of wind-induced non-Gaussian vibration. The first methodology synthesizes the non-Gaussian signal offline and replicates it on the shaker in the Time Waveform Replication (TWR) mode. A new synthesis method is used to model the non-Gaussian signal as a Gaussian signal multiplied by an amplitude modulation function (AMF). A case study is presented to show that the synthesized non-Gaussian signal has the same power spectral density (PSD), probability density function (PDF), and loading cycle distribution (LCD) as the field data. The second methodology derives a damage equivalent Gaussian signal from the non-Gaussian signal based on the fatigue damage spectrum (FDS) and the extreme response spectrum (ERS) and reproduces it on the shaker in the closed-loop frequency domain control mode. The PSD level and the duration time of the derived Gaussian signal can be manipulated for accelerated testing purpose. A case study is presented to show that the derived PSD matches the damage potential of the non-Gaussian environment for both fatigue and peak response.

Highway Network Bridge Fatigue Damage Potential of Special Truck Configurations

2000 ◽  
Vol 1696 (1) ◽  
pp. 81-92 ◽  
Author(s):  
Jeffrey A. Laman ◽  
John R. Ashbaugh
Keyword(s):  
Fatigue Damage ◽  
The United States ◽  
Fatigue Analysis ◽  
Primary Objective ◽  
Evaluation Tool ◽  
Damage Potential ◽  
Highway Network ◽  
Gross Vehicle Weight ◽  
Truck Size And Weight ◽  
Fatigue Evaluation

A study of the fatigue damage potential of special truck configurations was conducted to facilitate informed decisions by state transportation agencies in considering various truck size and weight and permit policies as well as to provide relative damage information that will be useful in ongoing network damage evaluations. The primary objective was to evaluate 78 existing common and FHWA-proposed truck configurations for relative fatigue damage potential. To accomplish this objective, an analytical fatigue evaluation tool was developed to determine the relative fatigue damage induced in highway network bridges by simulation of a highway fleet mix database crossing actual bridges modeled analytically. Additional objectives were to evaluate the influence of impact values and endurance limits used for a fatigue analysis. The semicontinuum analysis method, the Palmgren-Miner hypothesis, and the rain-flow cycle counting algorithm are incorporated. A 39-bridge database statistically selected as representative of bridges in the United States allowed a network level fatigue analysis of several hundred fatigue-prone details. Seventy-eight special truck configurations were studied, 25 of which were developed by FHWA as part of the comprehensive truck size and weight study. The remaining 53 vehicles were taken from the Turner proposal, Michigan, Pennsylvania, Canada, military, AASHTO, and other sources. It was found that fatigue damage potential is primarily a function of axle weight, spacing, and vehicle length instead of gross vehicle weight.

Testing the systems with fuzzy discrete components

2020 ◽  
Vol 6 (4) ◽  
pp. 518-531
Author(s):  
D. V. Speransky ◽  
◽  
A. V. Gorelik ◽  
I. A. Zhuravlev ◽  
A. V. Orlov ◽  
...  
Keyword(s):  
Intelligent Systems ◽  
Synthesis Method ◽  
Analytical Models ◽  
Synthesis Methods ◽  
Algebraic Equations ◽  
Mathematical Apparatus ◽  
Hybrid Intelligent Systems ◽  
Test Synthesis ◽  
Linear Algebraic Equations ◽  
Fuzzy Objects

Modern complex systems are build based on heterogeneous components with various interrela tionships, fuzziness, and uncertainty of the laws of functioning of the components and the system. An important class of such systems comprises hybrid intelligent systems, where the components are represented by analytical models of fuzzy objects, artifi cial neural networks, expert systems, etc. The article considers fuzzy discrete devices being, for example, part of hybrid systems. Fuzzy linear automata (FLA) introduced in the article are used as a mathematical model of such components. The problem of test synthesis for FLA used to detect faults in them is discussed. Normal single-stuck faults are permissible faults in FLA. The faults originating from the replacement of some elements of the FLA characteristic matrices with others (from a given set of alternative ones) are also permissible. Test synthesis methods for FLA belonging to the class of m-deterministic and synchronized automata, as well as arbitrary linear automata have been developed. The fi rst two methods are based on reducing the considered problem of solving systems of linear algebraic equations. It should be noted that there is a well-developed mathematical apparatus applying a few eff ective methods for searching for such solutions. The tests synthesized by these methods for m-deterministic and synchronized FLA are sufficiently short and do not exceed the memory depth of the corresponding automata. It is shown that the conditions for an FLA referring to the two fi rst classes mentioned above are not too strict. It is noted that the known methods of test synthesis for linear automata require compliance with much more stringent requirements. The synthesis method for arbitrary FLA also builds short tests

Sign in / Sign up

Export Citation Format

Share Document