scholarly journals Dynamic Repair and Robust Optimization of Complex Networks

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Pengtao Zhang ◽  
Peng Bai ◽  
Chaoqi Fu ◽  
Shanshan Li
Keyword(s):  
Energy Transfer ◽  
Repair Process ◽  
Recovery Efficiency ◽  
Repair Strategy ◽  
Coupling Structure ◽  
Secondary Failure ◽  
Fundamental Reason ◽  
Network Functions ◽  
The Impact ◽  
Failure Node

Network repair is indispensable for maintaining network security. Conventional static repair is relatively inefficient. In this study, by considering the energy transfer between nodes, a dynamic repair model was established. The fundamental reason for the secondary failure of repaired nodes during the dynamic repair process is the coupling structure of failure networks. A dynamic repair strategy was proposed that can effectively prevent the secondary failure of repair nodes influenced by energy during repair and can cause the redundant capacity of repair nodes to be used reasonably. By turning off the energy transfer function of the link to control the excessive flow of energy into the repair node to avoid the occurrence of secondary failure; on the other hand, by sharing part of the load of the failure node, realize the rational use of the redundant capacity of the repair node to reduce the impact of the failure node on the overall function of the network. The proposed strategy mitigated the effect of failure nodes on network functions and substantially improved the recovery efficiency of network functions. Furthermore, redundant edges, behaving as energy redundant links in a network structure, can considerably improve the robustness of the network by optimizing the removal of redundant edges. Dynamic repair is not only an efficient repair method but also a highly flexible choice for network repair.

Monitoring the Structural Dynamics of U2 snRNA Via Single-Molecule Förster Resonance Energy Transfer

2018 ◽  
Author(s):  
Alexander Carl DeHaven
Keyword(s):  
Energy Transfer ◽  
Structural Dynamics ◽  
Single Molecule ◽  
Conformational Dynamics ◽  
Resonance Energy Transfer ◽  
Resonance Energy ◽  
Förster Resonance Energy Transfer ◽  
U2 Snrna ◽  
Folding Dynamics ◽  
The Impact

This thesis contains four topic areas: a review of single-molecule microscropy methods and splicing, conformational dynamics of stem II of the U2 snRNA, the impact of post-transcriptional modifications on U2 snRNA folding dynamics, and preliminary findings on Mango aptamer folding dynamics.

scholarly journals Resolving the mesospheric nighttime 4.3 µm emission puzzle: comparison of the CO<sub>2</sub>(<i>ν</i><sub>3</sub>) and OH(<i>ν</i>) emission models

2017 ◽  
Vol 17 (16) ◽  
pp. 9751-9760 ◽  
Author(s):  
Peter A. Panka ◽  
Alexander A. Kutepov ◽  
Konstantinos S. Kalogerakis ◽  
Diego Janches ◽  
James M. Russell ◽  
...  
Keyword(s):  
Energy Transfer ◽  
Vibrational Energy ◽  
Lower Thermosphere ◽  
Vibrational Energy Relaxation ◽  
Density Distributions ◽  
Direct Mechanism ◽  
Vibrational Levels ◽  
Emission Models ◽  
The Impact ◽  
Good Agreement

Abstract. In the 1970s, the mechanism of vibrational energy transfer from chemically produced OH(ν) in the nighttime mesosphere to the CO2(ν3) vibration, OH(ν) ⇒ N2(ν) ⇒ CO2(ν3), was proposed. In later studies it was shown that this "direct" mechanism for simulated nighttime 4.3 µm emissions of the mesosphere is not sufficient to explain space observations. In order to better simulate these observations, an additional enhancement is needed that would be equivalent to the production of 2.8–3 N2(1) molecules instead of one N2(1) molecule in each quenching reaction of OH(ν) + N2(0). Recently a new "indirect" channel of the OH(ν) energy transfer to N2(ν) vibrations, OH(ν) ⇒ O(1D) ⇒ N2(ν), was suggested and then confirmed in a laboratory experiment, where its rate for OH(ν = 9) + O(3P) was measured. We studied in detail the impact of the "direct" and "indirect" mechanisms on CO2(ν3) and OH(ν) vibrational level populations and emissions. We also compared our calculations with (a) the SABER/TIMED nighttime 4.3 µm CO2 and OH 1.6 and 2.0 µm limb radiances of the mesosphere–lower thermosphere (MLT) and (b) with ground- and space-based observations of OH(ν) densities in the nighttime mesosphere. We found that the new "indirect" channel provides a strong enhancement of the 4.3 µm CO2 emission, which is comparable to that obtained with the "direct" mechanism alone but assuming an efficiency that is 3 times higher. The model based on the "indirect" channel also produces OH(ν) density distributions which are in good agreement with both SABER limb OH emission observations and ground and space measurements. This is, however, not true for the model which relies on the "direct" mechanism alone. This discrepancy is caused by the lack of an efficient redistribution of the OH(ν) energy from higher vibrational levels emitting at 2.0 µm to lower levels emitting at 1.6 µm. In contrast, the new  indirect  mechanism efficiently removes at least five quanta in each OH(ν ≥ 5) + O(3P) collision and provides the OH(ν) distributions which agree with both SABER limb OH emission observations and ground- and space-based OH(ν) density measurements. This analysis suggests that the important mechanism of the OH(ν) vibrational energy relaxation in the nighttime MLT, which was missing in the emission models of this atmospheric layer, has been finally identified.

scholarly journals Numerical Study Of The Targeted Energy Transfer Between The Euler-Bernoulli Beam And A Nonlinear Energy Sink

2021 ◽  
Author(s):  
Mohi U. Rahamat Ullah
Keyword(s):  
Energy Transfer ◽  
Primary Structure ◽  
Numerical Study ◽  
Element Model ◽  
Impact Excitation ◽  
Nonlinear Stiffness ◽  
Targeted Energy Transfer ◽  
Stiffness Property ◽  
Energy Sink ◽  
The Impact

Targeted energy transfer (TET) refers to the spatial transfer of energy between a primary structure of interest and isolated oscillators called the energy sink (ES). In this work, the primary structure of interest is a slender beam modeled by the Euler-Bernoulli theory, and the ES is a single-degree-of-freedom oscillator with either linear or cubic nonlinear stiffness property. The objective of this study is to characterize the TET and the effectiveness of ES under impact and periodic excitations. By using the scientific computation package, MATLAB, numerical simulations are carried out based on excitations of various strength and locations. Both time and frequency domain characterizations are used. For the impact excitation, the ES with the cubic nonlinear stiffness property is more superior to the linear oscillator in that larger percentage of the impact energy can be dissipated there. The main energy transfer was found to be due to a 3- to-1 frequency coupling between the first bending mode and the ES. For the periodic excitation, however, both linear and nonlinear ES exhibit generally poorer performance than the case with the impact excitation. Future works should focus on the frequency-energy relationship of the periodic solution of the underlying Hamiltonian, as well as using finite element model to verify the simulation results.

scholarly journals Dynamics of the Activity of MAP-Kinase Cascades in the Healing Process of Postoperative Musculocutaneous Wounds

2019 ◽  
Vol 4 (5) ◽  
pp. 55-59
Author(s):  
I. A. Shurygina ◽  
V. A. Umanets ◽  
M. G. Shurygin
Keyword(s):  
Map Kinase ◽  
Healing Process ◽  
Traumatic Injury ◽  
Repair Process ◽  
Modern Medicine ◽  
Peak Activity ◽  
Specific Staining ◽  
Mapk Cascades ◽  
Reparative Process ◽  
The Impact

Background. Management of the reparative process is an urgent task of modern medicine. In our opinion, the development of pathogenetically grounded approaches to optimizing the repair process for managing the interrelations of stromal cells is promising. One of the promising areas in this regard is the impact on the MAPK-cascades.Aim: to study the expression of MAP-kinase mechanisms in the regulation of repair by the example of a musculocutaneous wound.Methods. A linear muscular skin wound was modeled using Wistar rats weighing 220–250 g at the age of 9 months (n = 24). Immunofluorescence staining was performed to detect the activity of p38, JNK, and ERK MAPK cascades from 1 to 30 days.Results. It was established that specific staining in the area of connective tissue formation during staining with p38 MAPK and its phosphorylated form was first observed on the 3rd day, and its maximum severity occurred at the same time. On the 7th and 14th day, small zones in the area of scar formation were minimally stained. The phosphorylated part of the JNK-cascade in the zone of traumatic injury was detected starting from the 1st day after the injury. Bright color persisted on the 3rd day. On the 7th day, the color was minimal, and by the 14th day a second wave of expression was observed. ERK-staining was observed from the 1st to the 14th day with a peak activity on the 3rd day.Conclusion. Thus, we revealed the simultaneous involvement of p38, JNK-, and ERK-cascades in the regulation of the reparative process in the conditions of a musculoskeletal wound. At the same time, it is noteworthy that the peak activity of all cascades coincides and falls on the 3rd day.

scholarly journals Lifting a sessile oil drop from a superamphiphobic surface with an impacting one

2020 ◽  
Vol 6 (34) ◽  
pp. eaba4330
Author(s):  
Olinka Ramírez-Soto ◽  
Vatsal Sanjay ◽  
Detlef Lohse ◽  
Jonathan T. Pham ◽  
Doris Vollmer
Keyword(s):  
Surface Tension ◽  
Energy Transfer ◽  
Impact Velocity ◽  
Sessile Drop ◽  
Cloud Formation ◽  
Impact Dynamics ◽  
Combustion Engines ◽  
Intrinsic Properties ◽  
Natural Processes ◽  
The Impact

Colliding drops are encountered in everyday technologies and natural processes, from combustion engines and commodity sprays to raindrops and cloud formation. The outcome of a collision depends on many factors, including the impact velocity and the degree of alignment, and intrinsic properties like surface tension. Yet, little is known on binary impact dynamics of low-surface-tension drops on a low-wetting surface. We investigate the dynamics of an oil drop impacting an identical sessile drop sitting on a superamphiphobic surface. We observe five rebound scenarios, four of which do not involve coalescence. We describe two previously unexplored cases for sessile drop liftoff, resulting from drop-on-drop impact. Numerical simulations quantitatively reproduce the rebound scenarios and enable quantification of velocity profiles, energy transfer, and viscous dissipation. Our results illustrate how varying the offset from head-on alignment and the impact velocity results in controllable rebound dynamics for oil drop collisions on superamphiphobic surfaces.

scholarly journals Socialization, Connection, and The Structure/Agency Gap: A Specification of The Impact of Networks on Participation in Social Movements

2001 ◽  
Vol 6 (2) ◽  
pp. 173-192 ◽  
Author(s):  
Florence Passy
Keyword(s):  
Social Networks ◽  
Social Movement ◽  
Political Issue ◽  
Individual Preferences ◽  
Life History Data ◽  
Network Functions ◽  
Structural Connection ◽  
Movement Participation ◽  
The Impact

While numerous studies stress the crucial role of networks for social movement participation, they generally do not specify how networks affect individual behaviors. This article clarifies the role of social networks for individual social movement participation. It argues that networks perform three fundamental functions in the process leading to participation and that they intervene at different moments along this process. First, networks socialize and build individual identities—a socialization function. Second, they offer participation opportunities to individuals who are culturally sensitive to a specific political issue—a structural-connection function. Third, they shape individual preferences before individuals decide to join a move-ment—a decision-shaping function. These network functions allow us to disentangle the mechanisms at work in the process of participation. They also integrate structural and rationalist theories, which are often considered opposing explanations of individual movement participation. This article presents several hypotheses about these network functions, and uses both quantitative (survey) and qualitative (life history) data of participation in the Berne Declaration SMO to examine them.

Creating the circular advantage for the oil and gas industry

2016 ◽  
Vol 56 (2) ◽  
pp. 585
Author(s):  
Christopher Coldrick ◽  
Rowan Fenn ◽  
David Sahota
Keyword(s):  
Oil And Gas ◽  
Service Providers ◽  
Real Life ◽  
Oil And Gas Industry ◽  
Repair Process ◽  
Materials Management ◽  
Gas Industry ◽  
Management Processes ◽  
Oil And Gas Companies ◽  
The Impact

Maintenance, repair and operating (MRO) materials typically represent 15–20% of the operating costs for a mature oil and gas asset. Of this, a substantial proportion is comprised of high-value repairable equipment such as motors, compressors and pumps. This equipment is often at bottlenecks in the production process and so the impact of materials cost on profitability is magnified by the production ramifications of an outage. Effective management of this equipment is key to the sustainable, profitable operation of any oil and gas asset, and is key to improving the competitiveness of the Australian industry. Oil and gas companies are adopting a variety of models to handle the repair process, with varying degrees of success. Challenges include: poor materials availability and lack of traceability; complex infield materials management processes resulting in costly wastages; difficulty in managing consistency, suitability and specifications of repairs; high cost for those undertaking the repairs; and, correct allocation of responsibility and risk in the materials management process. Developed in collaboration with Australian oil and gas operators, with input from case studies outside the oil and gas industry, this extended abstract discusses the roles and opportunities for the circular economy in helping companies to meet their sustainability and profitability targets. Using several real-life examples, it makes recommendations for vendors, service providers and operators that can have material impact on the profitability of the industry.

Recovery Efficiency in Hydraulically Fractured Shale Gas Reservoirs

2017 ◽  
Vol 139 (4) ◽  
Author(s):  
Maxian B. Seales ◽  
Turgay Ertekin ◽  
John Yilin Wang
Keyword(s):  
Natural Gas ◽  
Shale Gas ◽  
Operating Conditions ◽  
Recovery Efficiency ◽  
British Petroleum ◽  
Gas Reservoirs ◽  
Shale Gas Reservoirs ◽  
Petroleum Company ◽  
The Impact ◽  
The U.S

At the end of 2015 the U.S. held 5.6% or approximately 369 Tcf of worldwide conventional natural gas proved reserves (British Petroleum Company, 2016, “BP Statistical Review of World Energy June 2016,” British Petroleum Co., London). If unconventional gas sources are considered, natural gas reserves rise steeply to 2276 Tcf. Shale gas alone accounts for approximately 750 Tcf of the technically recoverable gas reserves in the U.S. (U.S. Energy Information Administration, 2011, “Review of Emerging Resources: U.S. Shale Gas and Shale Oil plays,” U.S. Department of Energy, Washington, DC). However, this represents only a very small fraction of the gas associated with shale formations and is indicative of current technological limits. This manuscript addresses the question of recovery efficiency/recovery factor (RF) in fractured gas shales. Predictions of gas RF in fractured shale gas reservoirs are presented as a function of operating conditions, non-Darcy flow, gas slippage, proppant crushing, and proppant diagenesis. Recovery factors are simulated using a fully implicit, three-dimensional, two-phase, dual-porosity finite difference model that was developed specifically for this purpose. The results presented in this article provide clear insight into the range of recovery factors one can expect from a fractured shale gas formation, the impact that operation procedures and other phenomena have on these recovery factors, and the efficiency or inefficiency of contemporary shale gas production technology.

A fuzzy imperfect production and repair inventory model with time dependent demand, production and repair rates under inflationary conditions

2018 ◽  
Vol 52 (1) ◽  
pp. 217-239 ◽  
Author(s):  
Shalini Jain ◽  
Sunil Tiwari ◽  
Leopoldo Eduardo Cárdenas-Barrón ◽  
Ali Akbar Shaikh ◽  
Shiv Raj Singh
Keyword(s):  
Research Work ◽  
Repair Process ◽  
Inventory Model ◽  
Time Dependent ◽  
Imperfect Production ◽  
Imperfect Items ◽  
Demand Rate ◽  
The Impact ◽  
Varying Demand ◽  
Dependent Demand

This research work derives an integrated inventory model for imperfect production/remanufacturing process with time varying demand, production and repair rates under inflationary environment. This inventory model deals with the joint manufacturing and remanufacturing options. There is a collection process devoted to collect used items with the aim to remanufacture them. Both production and repair runs generate imperfect items. The repair process remanufactures used and imperfect items. Further, it is also considered that the remanufactured item that is classified as good has exactly same quality as that of new one. Demand rate is supposed as time dependent. The production rate is assumed to be demand dependent and therefore it is also time dependent. The repair rate is supposed to be a function of time. All system costs are contemplated in uncertain environment. Therefore, the costs are considered as fuzzy nature. Theoretical results are illustrated thru a numerical example. Finally, a sensitivity analysis is performed in order to know the impact of different parameters on the optimal policy.

Sign in / Sign up

Export Citation Format

Share Document