Venting Manhole Cover: A Nonlinear Spring-Mass System

2020 ◽  
Author(s):  
Arris S. Tijsseling ◽  
Jose G. Vasconcelos ◽  
Qingzhi Hou ◽  
Zafer Bozkuş
Keyword(s):  
Simple Model ◽  
Dynamic Behavior ◽  
Structural Damage ◽  
Heavy Rainfall ◽  
Road Traffic ◽  
Mass System ◽  
Strongly Nonlinear ◽  
Dangerous Situation ◽  
High Level ◽  
Air Column

Abstract Manholes are vertical shafts connecting underground sewers with street-level terminals. They are covered by heavy lids. During periods of heavy rainfall, the air column in the upper part of the manhole may be compressed to such high level that the lid moves up. Of course, this is a dangerous situation for pedestrians and road traffic. Bolting the lid may provide a solution to the problem, but it is known that air pressurization underneath can result in structural damage. A simple model is proposed to describe the lifting of the lid (manhole cover). When the lid moves up, air is allowed to escape so that the lifting pressure decreases and the lid moves down, whereupon the air pressure increases again. This repetition might lead to the realistic phenomenon of the dancing manhole cover. Since the model is strongly nonlinear, interesting dynamic behavior is expected.

Structure Damage Detection via the Behavior of Substructure

1991 ◽  
Author(s):  
J. H. Wang ◽  
C. S. Liou
Keyword(s):  
Damage Detection ◽  
Mechanical System ◽  
Dynamic Behavior ◽  
Structural Damage ◽  
Structure Damage

Abstract A mechanical system generally consists of many substructures. However, it is impossible to observe the dynamic behavior of any substructure directly when the whole structure is in operation. A method was proposed in this work to determine the FRFs of a substructure by using the measured FRFs of the whole structure and the priorly known FRFs of another substructure With this method, one can detect the structural damage more easily by observing the change of the FRFs of the damaged substructure.

scholarly journals A Feasibility Study of the Drive-By Method for Damage Detection in Railway Bridges

2019 ◽  
Vol 9 (1) ◽  
pp. 160 ◽  
Author(s):  
Marco Carnevale ◽  
Andrea Collina ◽  
Tim Peirlinck
Keyword(s):  
Structural Damage ◽  
Damage Identification ◽  
Train Track ◽  
Operational Parameters ◽  
Railway Bridges ◽  
Acceleration Sensors ◽  
Magnetic Inspection ◽  
Track Irregularity ◽  
High Level ◽  
Track Bridge

Damage identification and localization in railway bridges is a widely studied topic. Strain, displacement, or acceleration sensors installed on the bridge structure are normally used to detect changes in the global behavior of the structure, whereas approaches like ultra-sonic testing, acoustic emission, and magnetic inspection are used to check a small portion of structure near localized damage. The aim of this paper is to explore another perspective for monitoring the structural status of railway bridges, i.e., to detect structural damage from the dynamic response of the train transiting the bridge. This approach can successfully be implemented in the case of resonant bridges, thanks to the high level of acceleration generated, but its application becomes more challenging when the excitation frequencies due to train passage do not excite the first mode of vibration of the bridge. The paper investigates the feasibility of the method in the latter case, through numerical simulations of the complete train-track-bridge system. Accelerations on axleboxes and bogies are processed through suitable algorithms to detect differences arising when the train crosses a defective bridge or a healthy one. The results outline the main operational parameters affecting the method, the best placement for sensors, and the best frequency range to be considered in the signal processing, also addressing the issues that are related to track irregularity. Good performance can be achieved in the case of short bridges, but a few practical issues must be tackled before the method could be tested in practice.

Dose-Dependence of Pb-Ion Implantation Damage in Zirconolite, Hollandite, and Zircon

1981 ◽  
Vol 11 ◽  
Author(s):  
T. J. Headley ◽  
G. W. Arnold ◽  
C. J. M. Northrup
Keyword(s):  
Radiation Damage ◽  
Structural Damage ◽  
Accelerated Aging ◽  
Dose Dependence ◽  
High Level Waste ◽  
Long Term Stability ◽  
Waste Forms ◽  
Recent Approach ◽  
High Level

The long-term stability of nuclear waste forms is an important consideration in their selection for safe disposal of radioactive waste. Stability against long-term radiation damage is particularly difficult to assess by short-term laboratory experiments. Much of the displacement damage in high-level waste forms will be generated by heavy recoil nuclei emitted during the α-decay process of long-lived actinide elements. Hence, an accelerated aging test which reliably simulates the α-recoil damage accumulated during thousands of years of storage is desirable. One recent approach to this simulation is to implant the waste form with heavy Pb-ions.I- 6 If the validity of this approach is to be fully assessed, two important questions which have not yet been investigated must be answered.(1) Is the structural damage, including cumulative effects, similar for irradiation by Pb-ions and a-recoil nuclei in a given material? (2) Is the dose-dependence of the accumulated damage similar? The purpose of this investigation was to assess the extent of these similarities in selected materials. We utilized transmission electron microscopy (TEM) to characterize the radiation damage and measure its dose-dependence.

scholarly journals Reliability and Fatigue Analysis in Cantilever-Based MEMS Devices Operating in Harsh Environments

2014 ◽  
Vol 2014 ◽  
pp. 1-16 ◽  
Author(s):  
Mohammad Tariq Jan ◽  
Nor Hisham Bin Hamid ◽  
Mohd Haris Md Khir ◽  
Khalid Ashraf ◽  
Mohammad Shoaib
Keyword(s):  
Structural Damage ◽  
Focal Point ◽  
Operating Conditions ◽  
Harsh Environments ◽  
Mems Devices ◽  
Paris Law ◽  
Modern Engineering ◽  
Reliability Issue ◽  
High Level ◽  
Microfabrication Techniques

The microelectromechanical system (MEMS) is one of the most diversified fields of microelectronics; it is rated to be the most promising technology of modern engineering. MEMS can sense, actuate, and integrate mechanical and electromechanical components of micro- and nano sizes on a single silicon substrate using microfabrication techniques. MEMS industry is at the verge of transforming the semiconductor world into MEMS universe, apart from other hindrances; the reliability of these devices is the focal point of recent research. Commercialization is highly dependent on the reliability of these devices. MEMS requires a high level of reliability. Several technological factors, operating conditions, and environmental effects influencing the performances of MEMS devices must be completely understood. This study reviews some of the major reliability issues and failure mechanisms. Specifically, the fatigue in MEMS is a major material reliability issue resulting in structural damage, crack growth, and lifetime measurements of MEMS devices in the light of statistical distribution and fatigue implementation of Paris' law for fatigue crack accumulation under the influence of undesirable operating and environmental conditions.

Modeling and Dynamic Behavior of Battery Energy Storage: A Simple Model for Large-Scale Time-Domain Stability Studies

2015 ◽  
Vol 3 (3) ◽  
pp. 47-51 ◽  
Author(s):  
Pouyan Pourbeik ◽  
Stephen E. Williams ◽  
James Weber ◽  
Juan Sanchez-Gasca ◽  
Jay Senthil ◽  
...  
Keyword(s):  
Energy Storage ◽  
Simple Model ◽  
Dynamic Behavior ◽  
Time Domain ◽  
Large Scale ◽  
Stability Studies ◽  
Battery Energy Storage ◽  
Battery Energy ◽  
Domain Stability

scholarly journals Three-Dimensional Circulation Structure of Summer Heavy Rainfall in Central North China

2015 ◽  
Vol 30 (1) ◽  
pp. 238-250 ◽  
Author(s):  
Wei Sun ◽  
Rucong Yu ◽  
Jian Li ◽  
Weihua Yuan
Keyword(s):  
Heavy Rainfall ◽  
North China ◽  
Three Dimensional ◽  
Lower Troposphere ◽  
Northern China ◽  
Front Side ◽  
The North ◽  
Westerly Jet ◽  
High Level ◽  
Circulation Structure

Abstract Based on daily rainfall observations and Japanese 25-year Reanalysis Project data during ~1981–2010, a three-dimensional circulation structure that formed before heavy summer rainfall in central north China (CNC) is revealed in this study. Composite analyses of circulation in advance of 225 heavy rain days show that the circulation structure is characterized by a remarkable upper-tropospheric warm anomaly (UTWA), which covers most of northern China with a center at ~300 hPa. Under hydrostatic and geostrophic equilibriums, the UTWA contributes to the generation of an anticyclonic (cyclonic) anomaly above (below). The anticyclonic anomaly strengthens (weakens) westerly winds to the north (south) of the warm center and pushes the high-level westerly jet to the north. The cyclonic anomaly deepens the trough upstream of CNC and intensifies lower southwesterly winds to the mideast of the warm center. As a result, the northerly stretched high-level jet produces upper divergence in its right-front side and the intensified southwesterly winds induce lower moisture convergence in its left-front side, causing heavy rainfall in CNC. Correlation analyses further confirm the close connections between UTWA and circulation in the upper and lower troposphere. The correlation coefficients between UTWA and the upper geopotential height, upper westerly jet, and lower southerly flow reach 0.95, 0.70, and 0.39, implying that the two critical factors leading to intense rainfall in CNC, the high-level jet and the low-level southerly flow, are closely connected with the UTWA. Consequently, in the future analyses and forecasts of heavy rainfall over northern China, more attention should be paid to the temperature in the upper troposphere.

scholarly journals Road Traffic Noise Pollution a Hazard

1970 ◽  
Vol 42 (4) ◽  
pp. 435-440
Author(s):  
Tayyaba Aftab ◽  
Farzana Bashir ◽  
Tahira Shafiq
Keyword(s):  
Noise Level ◽  
Road Traffic ◽  
Traffic Noise ◽  
Working Hours ◽  
Noise Pollution ◽  
Road Traffic Noise ◽  
Engineering Controls ◽  
Frequent Use ◽  
High Level ◽  
Average Noise Level

A road traffic noise study was conducted in Lahore at 18 busy places of high traffic flow in peak working hours of the day. It has been found that the day time average noise level has crossed the permissible limit of 85dB(A) at 90% busy points in the city. The maximum average noise level recorded in Lahore was 104 dB(A). This high level attributed to vehicular traffic specially auto rickshaw with ineffective silencers (without filters) and frequent use of the pressure horns by buses, wagons and trucks etc. The findings of the survey provide enough baseline data for engineering controls and interim legislation against traffic noise pollution. Key words: Noise pollution, Traffics load , Community health, Lahore city Bangladesh J. Sci. Ind. Res. 42(4), 435-440, 2007

scholarly journals Spatiotemporal patterns of synchronous heavy rainfall events in East Asia during the Baiu season

2020 ◽  
Author(s):  
Frederik Wolf ◽  
Ugur Ozturk ◽  
Kevin Cheung ◽  
Reik V. Donner
Keyword(s):  
East Asia ◽  
Heavy Rainfall ◽  
Spatial Organization ◽  
Asian Summer Monsoon ◽  
Monsoon Season ◽  
Daily Rainfall ◽  
Heavy Precipitation ◽  
Extreme Weather Events ◽  
Window Approach ◽  
High Level

Abstract. Investigating the synchrony and interdependency of heavy rainfall occurrences is crucial to understand the underlying physical mechanisms and reduce physical and economic damages by improved forecasting strategies. In this context, studies utilizing functional network representations have recently contributed to significant advances in the understanding and prediction of extreme weather events. To thoroughly expand on previous works employing the latter framework to the East Asian Summer Monsoon (EASM) system, we focus here on changes in the spatial organization of synchronous heavy precipitation events across the monsoon season (April to August) by studying the temporal evolution of corresponding network characteristics in terms of a sliding window approach. Specifically, we utilize functional climate networks together with event coincidence analysis for identifying and characterizing synchronous activity from daily rainfall estimates between 1998 and 2018. Our results demonstrate that the formation of the Baiu front as a main feature of the EASM is reflected by a double-band structure of synchronous heavy rainfall with two centers north and south of the front. Although the two separated bands are strongly related to either low- or high-level winds which are commonly assumed to be independent, we provide evidence that it is rather their mutual interconnectivity that changes during the different phases of the EASM season in a characteristic way. Our findings shed some new light on the interplay between tropical and extratropical factors controlling the EASM intraseasonal evolution, which could potentially help to improve future forecasts of the Baiu onset in different regions of East Asia.

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