A novel shock isolator for heavy structure installation

2010 ◽  
Vol 224 (2) ◽  
pp. 283-292 ◽  
Author(s):  
L-J Zhang ◽  
C-M Zhu ◽  
X Shi ◽  
P Zhang
Keyword(s):  
External Disturbance ◽  
Large Mass ◽  
Peak Acceleration ◽  
Elastic Impact ◽  
Air Bags ◽  
Physical Limit ◽  
Huge Impact ◽  
The Impact ◽  
Heavy Structure ◽  
Impact Head

During the heavy structure installation process, any external disturbance may result in a huge impact on the substructure due to the extremely large mass involved, which may damage the whole structure permanently. Therefore, a reliable shock isolator for the installation interface is very important in such applications. In this study, a novel shock isolator based on a hydraulic damper is presented. It has been designed with an optimized throttling orifice to dissipate the energy efficiently and with air bags to store energy. Considering the maximal relative travel range of the isolator within a specified physical limit, the design is formulated as an optimization problem to minimize the peak acceleration during the impact and finalized as a constant force isolator. A mathematical model of the isolator is established and a prediction of its performance is obtained through some simulations. Experiments are performed to evaluate the theoretical model and it is found that the experimental data agree with the theoretical prediction very well, and thus validates the design. The influence of initial oil pressure and the material of elastic impact head are also investigated. The results show that higher initial oil pressure increases the peak acceleration, while the material of the elastic impact head has no significant effect on that.

scholarly journals Robust Position Control of a Two-Sided 1-DoF Impacting Mechanical Oscillator Subject to an External Persistent Disturbance by Means of a State-Feedback Controller

Complexity ◽  
2019 ◽  
Vol 2019 ◽  
pp. 1-14 ◽  
Author(s):  
Firas Turki ◽  
Hassène Gritli ◽  
Safya Belghith
Keyword(s):  
State Feedback ◽  
Position Control ◽  
External Disturbance ◽  
Feedback Controller ◽  
Linear Matrix ◽  
Stability Conditions ◽  
Mechanical Oscillator ◽  
Impact Oscillator ◽  
State Feedback Controller ◽  
The Impact

This paper proposes a state-feedback controller using the linear matrix inequality (LMI) approach for the robust position control of a 1-DoF, periodically forced, impact mechanical oscillator subject to asymmetric two-sided rigid end-stops. The periodic forcing input is considered as a persistent external disturbance. The motion of the impacting oscillator is modeled by an impulsive hybrid dynamics. Thus, the control problem of the impact oscillator is recast as a problem of the robust control of such disturbed impulsive hybrid system. To synthesize stability conditions, we introduce the S-procedure and the Finsler lemmas by only considering the region within which the state evolves. We show that the stability conditions are first expressed in terms of bilinear matrix inequalities (BMIs). Using some technical lemmas, we convert these BMIs into LMIs. Finally, some numerical results and simulations are given. We show the effectiveness of the designed state-feedback controller in the robust stabilization of the position of the impact mechanical oscillator under the disturbance.

scholarly journals Family reported outcomes, an unmet need in the management of a patient's disease: appraisal of the literature

2021 ◽  
Vol 19 (1) ◽  
Author(s):  
R. Shah ◽  
F. M. Ali ◽  
A. Y. Finlay ◽  
M. S. Salek
Keyword(s):  
Quality Of Life ◽  
Family Members ◽  
Unmet Need ◽  
Reliability And Validity ◽  
Chronic Health Condition ◽  
Family Quality Of Life ◽  
Good Reliability ◽  
Huge Impact ◽  
The Impact

Abstract Background A person’s chronic health condition or disability can have a huge impact on the quality of life (QoL) of the whole family, but this important impact is often ignored. This literature review aims to understand the impact of patients' disease on family members across all medical specialities, and appraise existing generic and disease-specific family quality of life (QoL) measures. Methods The databases Medline, EMBASE, CINHAL, ASSIA, PsycINFO and Scopus were searched for original articles in English measuring the impact of health conditions on patients' family members/partner using a valid instrument. Results Of 114 articles screened, 86 met the inclusion criteria. They explored the impact of a relative's disease on 14,661 family members, mostly 'parents' or 'mothers', using 50 different instruments across 18 specialities including neurology, oncology and dermatology, in 33 countries including the USA, China and Australia. These studies revealed a huge impact of patients' illness on family members. An appraisal of family QoL instruments identified 48 instruments, 42 disease/speciality specific and six generic measures. Five of the six generics are aimed at carers of children, people with disability or restricted to chronic disease. The only generic instrument that measures the impact of any condition on family members across all specialities is the Family Reported Outcome Measure (FROM-16). Although most instruments demonstrated good reliability and validity, only 11 reported responsiveness and only one reported the minimal clinically important difference. Conclusions Family members' QoL is greatly impacted by a relative's condition. To support family members, there is a need for a generic tool that offers flexibility and brevity for use in clinical settings across all areas of medicine. FROM-16 could be the tool of choice, provided its robustness is demonstrated with further validation of its psychometric properties.

scholarly journals Time Granularity Impact on Propagation of Disruptions in a System-of-Systems Simulation of Infrastructure and Business Networks

2021 ◽  
Vol 18 (8) ◽  
pp. 3922
Author(s):  
Mateusz Iwo Dubaniowski ◽  
Hans Rudolf Heinimann
Keyword(s):  
Recovery Time ◽  
System Of Systems ◽  
Future Research ◽  
Business Networks ◽  
Simulation Experiments ◽  
Huge Impact ◽  
High Level ◽  
Systems Simulation ◽  
Different Characteristics ◽  
The Impact

A system-of-systems (SoS) approach is often used for simulating disruptions to business and infrastructure system networks allowing for integration of several models into one simulation. However, the integration is frequently challenging as each system is designed individually with different characteristics, such as time granularity. Understanding the impact of time granularity on propagation of disruptions between businesses and infrastructure systems and finding the appropriate granularity for the SoS simulation remain as major challenges. To tackle these, we explore how time granularity, recovery time, and disruption size affect the propagation of disruptions between constituent systems of an SoS simulation. To address this issue, we developed a high level architecture (HLA) simulation of three networks and performed a series of simulation experiments. Our results revealed that time granularity and especially recovery time have huge impact on propagation of disruptions. Consequently, we developed a model for selecting an appropriate time granularity for an SoS simulation based on expected recovery time. Our simulation experiments show that time granularity should be less than 1.13 of expected recovery time. We identified some areas for future research centered around extending the experimental factors space.

Impact of Odd–Even Scheme on Travel Pattern in Delhi

2021 ◽  
Vol 17 (1) ◽  
pp. 27-38
Author(s):  
Palak Thakur ◽  
Sharif Qamar
Keyword(s):  
Air Pollution ◽  
Travel Time ◽  
Travel Pattern ◽  
Modal Shift ◽  
Daily Work ◽  
Transport Services ◽  
Huge Impact ◽  
Perception Analysis ◽  
The Impact ◽  
Public Transport Services

The paper intends to assess the impact of the odd–even scheme on the travel pattern of the daily commuters in Delhi. The objective of the paper is to assess the impact of the odd–even scheme on mode choice for daily work trips, shift in travel patterns – before, during, and post-implementation – of the odd–even scheme, and to understand people perception regarding the odd–even scheme. Based on the primary survey, the paper concludes that the odd–even scheme brought a significant impact in the travel pattern in terms of occupancy, travel cost, travel time, and modal shift, and statistically not so much on the air quality gain. It was observed that the scheme helped increase the occupancy rate in cars as well as ridership of buses and Delhi metro. The scheme had a huge impact on congestion, which was evident from both perception analysis and the change in travel time. The modal shift, with an improvement in public transport services and a reduction in car users, is one of the key successes of the scheme resulting in decrease in air pollution caused by private vehicles. To improve the outcome of the odd–even scheme on air pollution, two-wheelers should not be exempted going forward.

scholarly journals Management of colorectal cancer in the era of COVID-19: Challenges and suggestions

2021 ◽  
Vol 104 (2) ◽  
pp. 003685042110106
Author(s):  
Walid Alam ◽  
Youssef Bouferraa ◽  
Yolla Haibe ◽  
Deborah Mukherji ◽  
Ali Shamseddine
Keyword(s):  
Colorectal Cancer ◽  
Treatment Protocols ◽  
Cancer Management ◽  
Increased Risk ◽  
Huge Impact ◽  
Treatment Plans ◽  
Virus Exposure ◽  
Risk Of Exposure ◽  
Colorectal Cancer Patients ◽  
The Impact

The Coronavirus (COVID-19) pandemic had a huge impact on all sectors around the world. In particular, the healthcare system has been subject to an enormous pressure that has surpassed its ability in many instances. Additionally, the pandemic has called for a review of our daily medical practices, including our approach to colorectal cancer management where treatment puts patients at high risk of virus exposure. Given their higher median age, patients are at an increased risk for severe symptoms and complications in cases of infection, especially in the setting of immunosuppression. Therefore, a review of the routine colorectal cancer practices is needed to minimize risk of exposure. Oncologists should weigh risk of exposure versus the patient’s oncologic benefits when approaching management. In addition, treatment protocols should be modified to minimize hospital visits and admissions while maintaining the same treatment efficacy. In this review, we will focus on challenges that colorectal cancer patients face during the pandemic, while highlighting the priority in each case. We will also discuss the evidence for potential modifications to existing treatment plans that could reduce infectious exposure without compromising care. Finally, we will discuss the impact of the socio-economic difficulties faced by Lebanese patients due to a poor economy toppled by an unexpected pandemic.

scholarly journals COVID-19 Barometer: Social Opinion – What Do the Portuguese Think in This Time of COVID-19?

2021 ◽  
pp. 1-9
Author(s):  
Ana Rita Pedro ◽  
Ana Gama ◽  
Patrícia Soares ◽  
Marta Moniz ◽  
Pedro A. Laires ◽  
...  
Keyword(s):  
Health Services ◽  
Online Survey ◽  
Well Being ◽  
Point Of View ◽  
Daily Lives ◽  
The People ◽  
Huge Impact ◽  
The Impact ◽  
Continue Monitoring

The COVID-19 pandemic brought new challenges to the global community, reinforcing the role of public health in society. The main measures to combat it had (and still have) a huge impact on the daily lives of citizens. This investigation aimed to identify and monitor the population’s perceptions about how it faced this period and the impact on health, well-being, and daily life. In this study, we describe the main trends observed throughout the COVID-19 pandemic in terms of mental health status, confidence in the capacity of the health services to respond to the pandemic, and the use of health services by participants. The online survey collected responses from 171,947 individuals ≥16 years of age in Portugal, over a period of 15 weeks that started on 21 March 2020. Participants could fill the questionnaire once or weekly, which enabled us to analyse trends and variations in responses. Overall, 81% of the respondents reported having felt agitated, anxious, or sad during the COVID-19 pandemic; 19% did not experience these feelings. During the confinement period, the proportion of participants feeling agitated, anxious, or sad every day/almost every day ranged between 20 and 30%, but since the deconfinement this proportion decreased. Around 30% reported having more difficulty getting to sleep or to sleep all night; 28.4% felt more agitated; 25.5% felt sadder, discouraged, or cried more easily; and 24.7% felt unable to do everything they had to do, women more frequently than men. Overall, 65.8% of the participants reported feeling confident or very confident in the health services’ capacity to respond to the challenges associated with the pandemic, and this confidence increased over time. Concerning the people who needed a consultation, 35.6% had one in person and 20.8% had one remotely, but almost 44% did not have one due to cancellation by the service (27.2%) or their own decision not to go (16.3%). At this unusual time in which we find ourselves and based on our findings, it is essential to continue monitoring how the population is facing the different phases of the pandemic until it officially ends. Analysing the effects of the pandemic from the point of view of citizens allows for anticipating critical trends and can contribute to preventative action.

Impact of Different Film-Cooling Modes at Trailing Edge on the Aerodynamic Performance of Heavy Duty Gas Turbine Cascade

2011 ◽  
Vol 84-85 ◽  
pp. 259-263
Author(s):  
Xun Liu ◽  
Song Tao Wang ◽  
Xun Zhou ◽  
Guo Tai Feng
Keyword(s):  
Gas Turbine ◽  
Film Cooling ◽  
Large Mass ◽  
Turbine Cascade ◽  
Heavy Duty ◽  
Trailing Edge ◽  
Central Difference ◽  
Adiabatic Effectiveness ◽  
Heavy Duty Gas Turbine ◽  
The Impact

In this paper, the trailing edge film cooling flow field of a heavy duty gas turbine cascade has been studied by central difference scheme and multi-block grid technique. The research is based on the three-dimensional N-S equation solver. By way of analysis of the temperature field, the distribution of profile pressure, and the distribution of film-cooling adiabatic effectiveness in the region of trailing edge with different cool air injection mass and different angles, it is found that the impact on the film-cooling adiabatic effectiveness is slightly by changing the injection mass. The distribution of profile pressure dropped intensely at the pressure side near the injection holes line with the large mass cooling air. The cooling effect is good in the region of trailing edge while the injection air is along the direction of stream.

Is Turkey ready for the Post COVID-19 World Order?

2021 ◽  
Vol 23 (Summer 2021) ◽  
pp. 117-140
Author(s):  
Bora Bayraktar
Keyword(s):  
International Relations ◽  
Global Economy ◽  
Political System ◽  
Eastern Mediterranean ◽  
Eastern Mediterranean Region ◽  
World Order ◽  
New World Order ◽  
Daily Lives ◽  
Huge Impact ◽  
The Impact

The COVID-19 outbreak has had a huge impact on the global economy and politics. Closures and lockdowns stopped international trade resulting in an economic slowdown. It has changed the daily lives of people and the way business takes place. Politics has also been affected by the pandemic. Discussions about the changing world order have gained a new dimension and momentum. In this article, the impact of the COVID-19 pandemic in international relations is analyzed. Has COVID-19 triggered a change in the world order? If it has, what are the nature, scope, and content of this change? As a rising regional power in the Eastern Mediterranean region, how has Turkey been affected by this, and how did it respond to the changing situation? Signs of deteriorating world order, declining U.S. leadership, escalating geopolitical competition amongst global powers were in the air before the pandemic. Turkey’s adaptation to this new world order pre-dates the pandemic, when it changed its political system, and invested in its security and cohesion.

Design and analysis of a segmented blade for a 50 MW wind turbine rotor

2022 ◽  
pp. 0309524X2110693
Author(s):  
Alejandra S Escalera Mendoza ◽  
Shulong Yao ◽  
Mayank Chetan ◽  
Daniel Todd Griffith
Keyword(s):  
Wind Turbine ◽  
Large Mass ◽  
Turbine Rotor ◽  
Bolted Joints ◽  
Bonded Joints ◽  
Sheer Size ◽  
Extreme Scale ◽  
The Impact ◽  
Adhesive Materials ◽  
Wind Turbine Rotor

Extreme-size wind turbines face logistical challenges due to their sheer size. A solution, segmentation, is examined for an extreme-scale 50 MW wind turbine with 250 m blades using a systematic approach. Segmentation poses challenges regarding minimizing joint mass, transferring loads between segments and logistics. We investigate the feasibility of segmenting a 250 m blade by developing design methods and analyzing the impact of segmentation on the blade mass and blade frequencies. This investigation considers various variables such as joint types (bolted and bonded), adhesive materials, joint locations, number of joints and taper ratios (ply dropping). Segmentation increases blade mass by 4.1%–62% with bolted joints and by 0.4%–3.6% with bonded joints for taper ratios up to 1:10. Cases with large mass growth significantly reduce blade frequencies potentially challenging the control design. We show that segmentation of an extreme-scale blade is possible but mass reduction is necessary to improve its feasibility.

scholarly journals Comparison of branded rugby headguards on their effectiveness in reducing impact on the head

2018 ◽  
Vol 4 (1) ◽  
pp. e000361 ◽  
Author(s):  
Erin R A Frizzell ◽  
Graham P Arnold ◽  
Weijie Wang ◽  
Rami J Abboud ◽  
Tim S Drew
Keyword(s):  
Impact Force ◽  
Linear Acceleration ◽  
Baseline Measurement ◽  
Peak Acceleration ◽  
Impact Forces ◽  
Impact Attenuation ◽  
The Mean ◽  
Force Reduction ◽  
The Right ◽  
The Impact

AimTo compare the available brands of rugby headguards and evaluate their impact attenuation properties at various locations on the cranium, with regard to concussion prevention.MethodsSeven different branded headguards were fitted onto a rigid headform and drop-tested in three different positions. An accelerometer measured the linear acceleration the headform experienced on impact with the ground. Each test involved dropping the headform from a height that generated 103.8 g on average when bare, which is the closest acceleration to the upper limit of the concussion threshold of 100 g. A mean peak acceleration for each drop position was calculated and compared with the bare baseline measurement.ResultsEach headguard demonstrated a significant decrease in the mean peak acceleration from the baseline value (all p≤0.01). Overall the Canterbury Ventilator was the most effective headguard, decreasing the impact force on average by 47%. The least effective was the XBlades Elite headguard, averaging a force reduction of 27%. In five of the seven headguards, the right side of the headwear was the most effective at reducing impact force.ConclusionOverall, the results indicate that it would be beneficial to wear a headguard during rugby in order to reduce the impact forces involved in head collisions. There was also a clear difference in performance between the tested brands, establishing the Canterbury headguard as the most effective. However, only one model of headguard from each brand was tested, so further research evaluating all other models should be considered.

Sign in / Sign up

Export Citation Format

Share Document