scholarly journals Sharkskin-Inspired Magnetoactive Reconfigurable Acoustic Metamaterials

Research ◽  
2020 ◽  
Vol 2020 ◽  
pp. 1-13 ◽  
Author(s):  
Kyung Hoon Lee ◽  
Kunhao Yu ◽  
Hasan Al Ba’ba’a ◽  
An Xin ◽  
Zhangzhengrong Feng ◽  
...  
Keyword(s):  
First Generation ◽  
Logic Gates ◽  
Acoustic Metamaterials ◽  
On Demand ◽  
Mie Resonance ◽  
Frequency Regime ◽  
Physical Stimuli ◽  
Air Channels ◽  
Active Acoustic Metamaterials ◽  
Magnetoactive Elastomer

Most of the existing acoustic metamaterials rely on architected structures with fixed configurations, and thus, their properties cannot be modulated once the structures are fabricated. Emerging active acoustic metamaterials highlight a promising opportunity to on-demand switch property states; however, they typically require tethered loads, such as mechanical compression or pneumatic actuation. Using untethered physical stimuli to actively switch property states of acoustic metamaterials remains largely unexplored. Here, inspired by the sharkskin denticles, we present a class of active acoustic metamaterials whose configurations can be on-demand switched via untethered magnetic fields, thus enabling active switching of acoustic transmission, wave guiding, logic operation, and reciprocity. The key mechanism relies on magnetically deformable Mie resonator pillar (MRP) arrays that can be tuned between vertical and bent states corresponding to the acoustic forbidding and conducting, respectively. The MRPs are made of a magnetoactive elastomer and feature wavy air channels to enable an artificial Mie resonance within a designed frequency regime. The Mie resonance induces an acoustic bandgap, which is closed when pillars are selectively bent by a sufficiently large magnetic field. These magnetoactive MRPs are further harnessed to design stimuli-controlled reconfigurable acoustic switches, logic gates, and diodes. Capable of creating the first generation of untethered-stimuli-induced active acoustic metadevices, the present paradigm may find broad engineering applications, ranging from noise control and audio modulation to sonic camouflage.

Etiology and predictors of cluster attacks of hereditary angioedema that recur despite pharmaceutical treatment

2021 ◽  
Vol 42 (4) ◽  
pp. 317-324
Author(s):  
Felix. A. Johnson ◽  
Magdalena Wirth ◽  
Zhaojun Zhu ◽  
Janina Hahn ◽  
Jens Greve ◽  
...  
Keyword(s):  
Hereditary Angioedema ◽  
Upper Airway ◽  
Poor Quality ◽  
Prophylactic Therapy ◽  
On Demand ◽  
C1 Esterase Inhibitor ◽  
Physical Stimuli ◽  
Inhibitor Treatment ◽  
Esterase Inhibitor

Introduction: Hereditary angioedema (HAE) is a disease that leads to recurrent swelling of the skin and mucous membranes, including the upper airway tract. Apart from being deadly, these attacks can be debilitating, which leads to a poor quality of life in patients. Clinicians are occasionally confronted with patients who have recurrent attacks despite treatment with C1 esterase inhibitor concentrate or β2-receptor antagonists. The goal of this study was to investigate repeated attacks that occur 48 hours to 7 days (“cluster attacks”) after treatment, to determine why they occur and the factors that may be associated with them, and thus to prevent their occurrence. Methods: We conducted a multicenter mixed retrospective-prospective study with data acquired from all documented attacks in our patients with collective (n = 132) between 2015 and 2018. Results: Eighty-five percent (n = 132) of our total patient collective (N = 156) agreed to participate in the study. Nine percent of these patients (n = 12) had cluster attacks, with a total of 48 cluster attacks. The data procured from the patients were mixed retrospective‐prospective. Approximately 72% of all the cluster attacks were caused by exogenous stimuli (41% due to psychological stress, 29% due to physical stimuli, and 2% due to menstruation). Cluster attacks occurred in 7% of the patients who received prophylactic therapy in comparison with 12.5% of patients who received on-demand therapy. Cluster attacks comprised 48.4% of all the attacks that patients with cluster-attacks (n= 9) experienced. In addition, the patients who were underdosing their C1 esterase inhibitor treatment had cluster attacks more often. A lower “time to repeated attack” was seen in the patients who received on-demand therapy compared with those who received prophylactic therapy. Discussion: The percentage of the patients who had attacks as a result of exogenous triggers was higher in the cluster-attack group (70.5%) compared with the general HAE population (30‐42%). Repeated attacks, therefore, were strongly associated with external triggers. The patients who received prophylactic treatment and who experienced cluster attacks were highly likely to have been underdosing, which may explain the repeated attacks despite treatment. In the patients prone to cluster attacks, prophylaxis should be considered.

Active acoustic metamaterials with tunable effective mass density by gradient magnetic fields

2014 ◽  
Vol 105 (7) ◽  
pp. 071913 ◽  
Author(s):  
Xing Chen ◽  
Xianchen Xu ◽  
Shigang Ai ◽  
HaoSen Chen ◽  
Yongmao Pei ◽  
...  
Keyword(s):  
Magnetic Fields ◽  
Effective Mass ◽  
Mass Density ◽  
Acoustic Metamaterials ◽  
Active Acoustic Metamaterials

Recent Advances in Active Acoustic Metamaterials

2019 ◽  
Vol 11 (08) ◽  
pp. 1950081 ◽  
Author(s):  
Sanjay Kumar ◽  
Heow Pueh Lee
Keyword(s):  
Sound Wave ◽  
Dynamic Responses ◽  
Acoustic Metamaterials ◽  
Design Strategies ◽  
Acoustic Characteristics ◽  
Early 21St Century ◽  
Active Metamaterials ◽  
Potential Applications ◽  
Restricted Use ◽  
Active Acoustic Metamaterials

Since its first demonstration of an acoustic metamaterial in the early 21st century, it is widely used for sound wave manipulation purposes in many applications such as aerospace, automotive, defense, marine, etc. However, the traditional acoustic metamaterials display acoustic characteristics for restricted use because of their fixed structures. For real-world applications, the active sound wave manipulation is desirable. In recent years, active acoustic metamaterials (AAMs) have garnered attention owing to their unique design and material characteristics, which result in various dynamic responses against the incoming sound wave. This paper aims to provide an overview of the fundamental concept of active metamaterials, describing the multiple tuning mechanisms and design strategies, and highlighting their potential applications. The current fabrication challenges and future outlook in this promising field are also discussed.

scholarly journals The influence of geometry of primary air channels in standard retort burners on dust emission

2019 ◽  
Vol 254 ◽  
pp. 04009 ◽  
Author(s):  
Bartosz Ciupek ◽  
Jarosław Bartoszewicz
Keyword(s):  
First Generation ◽  
Research Work ◽  
Dust Emission ◽  
Geometrical Model ◽  
Technical Parameters ◽  
Work Settings ◽  
Air Supply ◽  
Air Channels ◽  
The Impact ◽  
Power Boiler

The article presents the analysis of dust emissions from a low power boiler fired with various solid fuels. The boiler, presented for testing, met the emission conditions for boilers made in the third class in accordance with the PN-EN 303-5: 2012 standard. The solid fuel boiler was equipped with two different retort burners with automatic fuel supply. For the test were used a first generation retort burner with a fixed rim and the next were used second generation retort burner provided with a rotary rim. Both constructions differ in the geometrical model of the primary air supply system to the furnace. During the tests, the work of the burners was controlled using a microprocessor temperature controller. During the research, the rotation time of the screw supplying the fuel through the retort to the furnace was changed, as well as the rotational speed of the blast fan impeller responsible for supplying the combustion air. The purpose of the tests was to check whether the boiler will meet the highest environmental class regardless of the technical parameters of the burner and fuel used. The article describes the research methodology and analysis of the results obtained. The effect of the tests carried out is a comparison of average dust emission values depending on the fuel used and the work settings of a given burner. The test results are a prerequisite for further research work in terms of the impact of primary air supply on the emission of harmful substances.

Applicability of Dynamic Homogenization for Acoustic Metamaterials

2014 ◽  
Author(s):  
Ankit Srivastava ◽  
Sia Nemat-Nasser
Keyword(s):  
Negative Refraction ◽  
Effective Properties ◽  
Dynamic Properties ◽  
Low Frequency ◽  
Bloch Wave ◽  
Acoustic Metamaterials ◽  
Infinite Domain ◽  
True Negative ◽  
Periodic Composite ◽  
Frequency Regime

Dynamic homogenization seeks to define frequency dependent effective properties for heterogeneous composites for the purpose of studying wave propagation in them. These properties can be used to predict and design for metamaterial behavior. However, there is an approximation involved in replacing a heterogeneous composite with its homogenized equivalent. In this paper we propose a quantification to this approximation. By way of explicit examples we show that a comprehensive homogenization scheme proposed in earlier papers is applicable in a finite composite setting and in the low frequency regime. We also show that there exist good arguments for considering the second branch of a locally resonant composite a true negative branch. Furthermore, we note that infinite-domain homogenization is more applicable to finite cases of locally resonant metamaterial composites than it is to 2-phase composites. We also study the effect of the interface location on the applicability of homogenization. The results open intriguing questions regarding the effects of replacing a semi-infinite periodic composite with its Bloch-wave (infinite domain) dynamic properties on such phenomenon as negative refraction.

Analysis on Efficiency of Power Generation for Various Sun Tracking and Fixed Solar Cells under Different Sunshine Environment

2011 ◽  
Vol 130-134 ◽  
pp. 1286-1294
Author(s):  
Chang Chun Wang ◽  
Kuang Jang Lin
Keyword(s):  
Solar Cells ◽  
Solar Radiation ◽  
Solar Energy ◽  
First Generation ◽  
Crystalline Silicon ◽  
Dye Sensitized ◽  
The Third ◽  
On Demand ◽  
Dc Power ◽  
Set Up

Solar energy directly converses light energy into DC power without fuel, no moving parts, no pollution, and no noise with long life-span more than about twenty years. Its application is extensive and the set up of solar generation can be scattered and in a small amount on demand which is the most available of all renewable energy, and is the most practical and effective energy. There are many kinds of solar cell, such first generation as Mono-crystalline Silicon, Multi-crystalline Silicon, and Amorphous Silicon, the second generation as Film Photovoltaic and the third generation as Dye-Sensitized (DSSCs) etc. The utilization of solar energy is greatly influenced by environmental change with the main reason of solar radiation. This research collects the data from the test of Mono-crystalline Silicon, Multi-crystalline Silicon, and Film Photovaltaic solar cells in different solar radiation, and then conducts the analysis and research thereby. Using the program written by Labview, collect the data of voltage, current, and the power, solar radiation, and temperature emitted by solar cells under test for analysis. And then discuss the results of the collected data by Matlab for data analysis.

scholarly journals Justice as a Service

2021 ◽  
Vol 38 ◽  
pp. 02007
Author(s):  
Paolo Fantozzi ◽  
Luigi Laura ◽  
Antonio Nuzzo ◽  
Riccardo Piselli
Keyword(s):  
Language Processing ◽  
First Generation ◽  
Legal Issues ◽  
End User ◽  
Public Companies ◽  
On Demand ◽  
Legal Challenges ◽  
Private And Public ◽  
Flight Delay ◽  
Demand Service

In this paper we address an emerging service, called Justice as a Service (JaaS), that has been defined as an on-demand service, powered by tech, that challenges private and public companies by representing the consumer in their fight for justice/compensation based on laws, consumers’ rights, and contract of carriage. Indeed, in recent years we have witnessed the birth of several JaaS companies, that are devoted to a certain type of claim such as compensation for flight delay or cancellation, or refunds for late shipping. However, as we will discuss in the paper, we do believe that these are only the first generation of JaaS systems, i.e. the ones that solve easy problems. The advances in Natural Language Processing models such as the very recent GPT-3, together with the availability of suits data in electronic form, will soon allow the rise of more complex systems, able either to assist lawyers in the preparation of cases or to assist the end user in more involved legal issues. In the paper, we discuss the technical and legal challenges of these new systems.

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