An Observer Based Framework to Improve Fidelity in Internet-Distributed Hardware-in-the-Loop Simulations

2013 ◽  
Author(s):  
Akshar Tandon ◽  
Mark J. Brudnak ◽  
Jeffrey L. Stein ◽  
Tulga Ersal
Keyword(s):  
Negative Impact ◽  
System Simulation ◽  
Significant Loss ◽  
Hardware In The Loop ◽  
Sliding Surface ◽  
Networked System ◽  
Vehicle Engine ◽  
Engine Driver ◽  
The Stability ◽  
Mass Spring

Co-simulating distributed hardware-in-the-loop systems in real time over the Internet entails communication delays that can lead to significant loss of fidelity and even instability in the system. To address this challenge, this paper proposes an observer based framework that, unlike previously reported efforts, does not require the observer to know and model the observed system dynamics. This is achieved by deriving the closed-loop dynamics of the observer based on a sliding surface. Even though the resulting error system does not necessarily stay on a sliding surface, its asymptotic convergence to zero is still guaranteed. First, this idea is developed for a generic networked system simulation framework and its stability is established. Then, it is applied to a mass-spring-damper system to illustrate the mechanics of the approach on a simple, linear example and demonstrate that the approach can stabilize the system that is otherwise unstable due to delay. Finally, a vehicle-engine-driver system simulation is considered to evaluate the performance of the approach on a more realistic, nonlinear example. An improvement of up to 33% is observed in the fidelity of the simulation. The conclusion is that the approach holds a significant potential to alleviate the negative impact of delay and improve the stability and fidelity of networked system simulations. Its benefits become more pronounced as the delay increases.

Political aspects of security of the European Union Member States

2020 ◽  
pp. 97-105
Author(s):  
Aleksandra Kusztykiewicz-Fedurek
Keyword(s):  
European Union ◽  
Negative Impact ◽  
The European Union ◽  
Member States ◽  
Eu Member States ◽  
Political Security ◽  
New Institutions ◽  
The Stability ◽  
Key Aspects ◽  
The Eu

Political security is very often considered through the prism of individual states. In the scholar literature in-depth analyses of this kind of security are rarely encountered in the context of international entities that these countries integrate. The purpose of this article is to draw attention to key aspects of political security in the European Union (EU) Member States. The EU as a supranational organisation, gathering Member States first, ensures the stability of the EU as a whole, and secondly, it ensures that Member States respect common values and principles. Additionally, the EU institutions focus on ensuring the proper functioning of the Eurozone (also called officially “euro area” in EU regulations). Actions that may have a negative impact on the level of the EU’s political security include the boycott of establishing new institutions conducive to the peaceful coexistence and development of states. These threats seem to have a significant impact on the situation in the EU in the face of the proposed (and not accepted by Member States not belonging to the Eurogroup) Eurozone reforms concerning, inter alia, appointment of the Minister of Economy and Finance and the creation of a new institution - the European Monetary Fund.

Slope Stability Analysis under the Condition of Seepage

2012 ◽  
Vol 204-208 ◽  
pp. 241-245
Author(s):  
Yang Jin
Keyword(s):  
Finite Element Method ◽  
Shear Strength ◽  
Slope Stability ◽  
Negative Impact ◽  
Strength Reduction ◽  
Soil Slope ◽  
Failure State ◽  
Calculation Results ◽  
The Stability ◽  
Shear Strength Reduction

The stability of soil slope under seepage is calculated and analyzed by using finite element method based on the technique of shear strength reduction. When the condition of seepage or not is considered respectively, the critical failure state of slopes and corresponding safety coefficients can be determined by the numerical analysis and calculation. Besides, through analyzing and comparing the calculation results, it shows that seepage has a negative impact on slope stability.

scholarly journals Reliable Learning with PDE-Based CNNs and DenseNets for Detecting COVID-19, Pneumonia, and Tuberculosis from Chest X-Ray Images

Mathematics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 434
Author(s):  
Anca Nicoleta Marginean ◽  
Delia Doris Muntean ◽  
George Adrian Muntean ◽  
Adelina Priscu ◽  
Adrian Groza ◽  
...  
Keyword(s):  
Transfer Learning ◽  
Negative Impact ◽  
X Ray ◽  
Domain Specific ◽  
Direct Training ◽  
Public Data ◽  
Normal Chest ◽  
Chest X Ray ◽  
The Stability ◽  
Definition Of

It has recently been shown that the interpretation by partial differential equations (PDEs) of a class of convolutional neural networks (CNNs) supports definition of architectures such as parabolic and hyperbolic networks. These networks have provable properties regarding the stability against the perturbations of the input features. Aiming for robustness, we tackle the problem of detecting changes in chest X-ray images that may be suggestive of COVID-19 with parabolic and hyperbolic CNNs and with domain-specific transfer learning. To this end, we compile public data on patients diagnosed with COVID-19, pneumonia, and tuberculosis, along with normal chest X-ray images. The negative impact of the small number of COVID-19 images is reduced by applying transfer learning in several ways. For the parabolic and hyperbolic networks, we pretrain the networks on normal and pneumonia images and further use the obtained weights as the initializers for the networks to discriminate between COVID-19, pneumonia, tuberculosis, and normal aspects. For DenseNets, we apply transfer learning twice. First, the ImageNet pretrained weights are used to train on the CheXpert dataset, which includes 14 common radiological observations (e.g., lung opacity, cardiomegaly, fracture, support devices). Then, the weights are used to initialize the network which detects COVID-19 and the three other classes. The resulting networks are compared in terms of how well they adapt to the small number of COVID-19 images. According to our quantitative and qualitative analysis, the resulting networks are more reliable compared to those obtained by direct training on the targeted dataset.

Dynamic analysis and control of an active engine mount system

2002 ◽  
Vol 216 (11) ◽  
pp. 921-931 ◽  
Author(s):  
Y-W Lee ◽  
C-W Lee
Keyword(s):  
Transfer Function ◽  
Dynamic Characteristics ◽  
Performance Test ◽  
Adaptive Controller ◽  
Lms Algorithm ◽  
Equivalent Mass ◽  
Engine Mount ◽  
Active Engine ◽  
The Stability ◽  
Mass Spring

Dynamic characteristics of a prototype active engine mount (AEM), designed on the basis of a hydraulic engine mount, have been investigated and an adaptive controller for the AEM has been designed. An equivalent mass-spring-damper AEM model is proposed, and the transfer function that describes the dynamic characteristics of the AEM is deduced from mathematical analysis of the model. The damping coefficient of the model is derived by considering the non-linear flow effect in the inertia track. Experiments confirmed that the model precisely describes the dynamic characteristics of the AEM. An adaptive controller using the filtered-X LMS algorithm is designed to cancel the force transmitted through the AEM. The stability of the LMS algorithm is guaranteed by using the secondary path transfer function derived on the basis of the dynamic model of the AEM. The performance test in the laboratory shows that the AEM system is capable of significantly reducing the force transmitted through the AEM.

ANTIBIOTIC STABILITY IN SOLUTIONS USED FOR INTRAVENOUS NUTRITION AND FLUID THERAPY

PEDIATRICS ◽  
1973 ◽  
Vol 51 (6) ◽  
pp. 1016-1026
Author(s):  
Ralph D. Feigin ◽  
Kanneth S. Moss ◽  
Penelope G. Shackelford
Keyword(s):  
Antimicrobial Activity ◽  
Normal Saline ◽  
Protein Hydrolysate ◽  
Significant Degree ◽  
Significant Loss ◽  
All Solutions ◽  
Ringer’S Lactate ◽  
Series Of Experiments ◽  
The Stability ◽  
Crystalline Amino Acids

The present study was designed to assess the stability of ampicillin, carbenicillin, clindamycin, kanamycin, cephalothin, methicillin, and penicillin in three parenteral hyperalimentation mixtures as reconstituted for delivery to the patient in the clinical setting. Stability at 4C, 25C, and 37C was tested in parenteral hyperalimentation mixtures containing either crystalline amino acids or a protein hydrolysate. In two series of experiments the stability at 4C, 25C, and 37C of ampicillin, cephalothin, and kanamycin also was assessed in Isolyte M (ISO M), Isolyte P (ISO P), Ringer's lactate (LR), 5% dextrose in water, (D5W), 10% dextrose in water (D1OW), dextrose in normal saline (D5S), and normal saline (NS) to which hydrocortisone or heparin had been added. All antibiotics retained their effectiveness at an acceptable level in the hyperalimentation solutions at 4C. At 25C and 37C, all antibiotics except clindamycin lost activity by 24 hours. Kanamycin was least stable in these solutions and ampicillin also lost a significant degree of antimicrobial activity. Addition of heparin or hydrocortisone imparted stability to ampicillin in the seven parenteral solutions although significant loss of activity was noted at 37C in D5W, D1OW, D5S, and LR. Most solutions containing heparin or hydrocortisone and cephalothin turned yellow by 24 hours. A precipitate appeared in solutions containing heparin and kanamycin but there was minimal loss of antimicrobial activity. Kanamycin was stable in all solutions containing hydrocortisone except in D5W and D10W at 37C.

Discrete-Time H-Infinity Synthesis of Frequency-Shaped Sliding Mode Control for Suppression of Vibration With Multiple Peak Frequencies

2016 ◽  
Author(s):  
Minghui Zheng ◽  
Masayoshi Tomizuka
Keyword(s):  
High Frequency ◽  
Sliding Mode ◽  
Disk Drive ◽  
Sliding Surface ◽  
Surface Dynamics ◽  
H Infinity ◽  
High Frequencies ◽  
Multiple Peak ◽  
Significant Performance ◽  
The Stability

Vibration with multiple large peaks at high frequencies may cause significant performance degradation and have become a major concern in modern high precision control systems. To deal with such high-frequency peaks, it is proposed to design a frequency-shaped sliding mode controller based on H∞ synthesis. It obtains an ‘optimal’ filter to shape the sliding surface, and thus provides frequency-dependent control allocation. The proposed frequency-shaping method assures the stability in the presence of multiple-peak vibration sources, and minimizes the weighted H∞ norm of the sliding surface dynamics. The evaluation is performed on a simulated hard disk drive with actual vibration sources from experiments, and the effectiveness of large vibration peak suppression is demonstrated.

LPV Based Sliding Mode Control for Limit Protection of Aircraft Engines

2018 ◽  
Author(s):  
Shubo Yang ◽  
Xi Wang
Keyword(s):  
Closed Loop ◽  
Sliding Mode ◽  
Aircraft Engine ◽  
Gain Scheduling ◽  
Engine Control ◽  
Aircraft Engines ◽  
Sliding Surface ◽  
Closed Loop System ◽  
Limit Protection ◽  
The Stability

Limit protection, which frequently exists as an auxiliary part in control systems, is not the primary motive of control but is a necessary guarantee of safety. As in the case of aircraft engine control, the main objective is to provide the desired thrust based on the position of the throttle; nevertheless, limit protection is indispensable to keep the engine operating within limits. There are plenty of candidates that can be applied to design the regulators for limit protection. PID control with gain-scheduling technique has been used for decades in the aerospace industry. This classic approach suggests linearizing the original nonlinear model at different power-level points, developing PID controllers correspondingly, and then scheduling the linear time-invariant (LTI) controllers according to system states. Sliding mode control (SMC) is well-known with mature theories and numerous successful applications. With the one-sided convergence property, SMC is especially suitable for limit protection tasks. In the case of aircraft engine control, SMC regulators have been developed to supplant traditional linear regulators, where SMC can strictly keep relevant outputs within their limits and improve the control performance. In aircraft engine control field, we all know that the plant is a nonlinear system. However, the present design of the sliding controller is carried out with linear models, which severely restricts the valid scope of the controller. Even if the gain scheduling technique is adopted, the stability of the whole systems cannot be theoretically proved. Research of linear parameter varying (LPV) system throws light on a class of nonlinear control problems. In present works, we propose a controller design method based on the LPV model to solve the engines control problem and achieve considerable effectiveness. In this paper, we discuss the design of a sliding controller for limit protection task of aircraft engines, the plant of which is described as an LPV system instead of LTI models. We define the sliding surface as tracking errors and, with the aid of vertex property, present the stability analysis of the closed-loop system on the sliding surface. An SMC law is designed to guarantee that the closed-loop system is globally attracted to the sliding surface. Hot day (ISA+30° C) takeoff simulations based on a reliable turbofan model are presented, which test the proposed method for temperature protection and verify its stability and effectiveness.

scholarly journals Daya Tahan Sektor Rumah Tangga Dalam Rangka Menjaga Stabilitas Sistem Keuangan

2018 ◽  
Vol 5 (1) ◽  
pp. 65
Author(s):  
Ita Rakhmawati ◽  
Suhadi Suhadi
Keyword(s):  
Interest Rates ◽  
Time Series Data ◽  
Negative Impact ◽  
Financial System ◽  
Series Data ◽  
Price Stability ◽  
Economic Stability ◽  
Independent Variables ◽  
High Inflation ◽  
The Stability

The crisis in 1997 is the image of the high rise in inflation in Indonesia. The phenomenon of inflation when it reached 82.40% (Anas, 2006). The early mid-1998 also experienced a weakening of the rupiah against the dollar. Condition stable economy is the desire of each country in comparison with the state of the economy has always fluctuated. Economic stability will create an atmosphere conducive economy. stable climatic conditions in the expected level of welfare is the purpose in each country. One of the efforts to maintain economic stability is through monetary policy. For example, with economic growth, maintain price stability (inflation), the achievement of the balance of payments and the reduction of unemployment (Natsir, 2008). The stability of the financial system of a country of which reflected their price stability, in the sense that there are a great price that can be harmful to society, both consumers and manufacturers that will damage the joints of the economy. However, the implementation of the policy, Bank Indonesia as the monetary authority uses monetary variables such as interest rates and the money supply to cope with economic shocks such as inflation. Besides the need for the government’s role in maintaining the rupiah to avoid turmoil in the economy. The importance of inflation control based on the consideration that the high inflation and unstable negative impact on socio-economic conditions of society. Among the high inflation will cause a decline in the real income of the community so that the standard of living of the people down and eventually make everyone, especially the poor get poorer. From one of the effects of inflation are so wide will impact people’s demands to meet the needs of more and more difficult. Their continuousprice increases being offset by rising income of the communities, it can make sure the Indonesian state would worsen. As a result many people’s needs can not be met, so many things that must be met by way of credit. The number of community needs that must be met will cause world of opportunities for banks to offer credit readily available to meet the needs. The third object of research above (inflation, poverty, and credit) does affect the stability of the financial system? In this study using secondary data from the Badan Pusat Statistik (BPS) and Bank Indonesia (BI) with time series data from the years 2007-2015. The process of data analysis was performed using OLS regression with Eviews 8.0. Based on research, if only partial test of the poverty variable significantly affect the stability of the financial system amounted to 2,023 with α = 10%. Meanwhile, two other variables (inflation and poverty) is not significant to the stability of the financial systemMeanwhile, two other variables (inflation and poverty) is not significant to the stability of the financial system. While the value of R-Square (0.629900), indicating that the three independent variables / free consisting of inflation, poverty and credit simultaneously have the effect that make the stabilization of the financial system increases or decreases. That is jointly independent variables (inflation, poverty and loans) contributed / effect of 62.9% against the stability of the financial system. The rest is the influence of other factors beyond the three independent variables studied.

scholarly journals COVID-19 PANDEMICS AS A FACTOR OF DESTABILIZATION OF INTERNATIONAL SUPPLY CHAINS

2021 ◽  
Vol 1 (24) ◽  
pp. 57-63
Author(s):  
Yu.A. Nikitin ◽  
◽  
M.A. Plotnik ◽  
◽  
Keyword(s):  
Supply Chains ◽  
Negative Impact ◽  
Global Supply Chains ◽  
The Stability ◽  
National Economies

The paper contains an analysis of the negative impact of the Covid-19 pandemics on the global supply chains. The reasons of this negative impact are identified. It is demonstrated that the Covid-19 pandemics is not the only threat for the stability of supply chains. Recommendations for the increase of stability of global supply chains for their members and for national economies are formulated.

A different fixation of the femoral component in total knee arthroplasty may lead to preservation of femoral bone stock

2003 ◽  
Vol 217 (5) ◽  
pp. 325-332 ◽  
Author(s):  
M Barink ◽  
N Verdonschot ◽  
M de Waal Malefijt
Keyword(s):  
Femoral Component ◽  
Knee Arthroplasty ◽  
Bone Remodelling ◽  
Significant Loss ◽  
Bone Stock ◽  
Femoral Bone ◽  
Secondary Effects ◽  
Total Knee ◽  
The Stability

Good femoral bone stock is important for the stability of the femoral component in revision knee arthroplasty. However, the primary total knee replacement (TKR) may cause significant loss of bone stock in the distal anterior femur. Earlier stress-induced bone remodelling simulations have suggested that a completely debonded component may save bone stock in the distal anterior region. However, these simulations did not consider the fixation of a debonded implant and possible secondary effects of micromotions and osteolysis at the interface. The current study tries to combine the preservation of bone stock with adequate component fixation. Different bone remodelling simulations were performed around femoral knee components with different sizes of bonding area and different friction characteristics of the debonded area. The fixation of the femoral component with different bonding characteristics is quantified with calculated implant-bone interface stresses. The results show that a bonded femoral component with a debonded inner side of the anterior flange may significantly reduce bone resorption in the endangered distal anterior femur, without jeopardizing the fixation of the femoral implant. This effect may be obtained in vivo by using a femoral component with a highly polished inner side of the anterior flange.

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