scholarly journals Acoustic Properties of Larch Bark Panels

Forests ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 887
Author(s):  
Eugenia Mariana Tudor ◽  
Lubos Kristak ◽  
Marius Catalin Barbu ◽  
Tomáš Gergeľ ◽  
Miroslav Němec ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Fine Particles ◽  
Raw Material ◽  
Acoustic Properties ◽  
Particle Orientation ◽  
Coarse Grained ◽  
Tree Bark ◽  
Parallel Orientation ◽  
Fine Grained ◽  
Reduction Coefficient

The potential of tree bark, a by-product of the woodworking industry, has been studied for more than seven decades. Bark, as a sustainable raw material, can replace wood or other resources in numerous applications in construction. In this study, the acoustic properties of bark-based panels were analyzed. The roles of the particle size (4–11 mm and 10–30 mm), particle orientation (parallel and perpendicular) and density (350–700 kg/m3) of samples with 30 mm and 60 mm thicknesses were studied at frequencies ranging from 50 to 6400 Hz. Bark-based boards with fine-grained particles have been shown to be better in terms of sound absorption coefficient values compared with coarse-grained particles. Bark composites mixed with popcorn bonded with UF did not return the expected results, and it is not possible to recommend this solution. The best density of bark boards to obtain the best sound absorption coefficients is about 350 kg/m3. These lightweight panels achieved better sound-absorbing properties (especially at lower frequencies) at higher thicknesses. The noise reduction coefficient of 0.5 obtained a sample with fine particles with a parallel orientation and a density of around 360 kg/m3.

scholarly journals Crumb Rubber Effect on Acoustic Properties of Self- Consolidating Concrete

2014 ◽  
Vol 08 (2) ◽  
Keyword(s):  
Experimental Study ◽  
Noise Reduction ◽  
Sound Absorption ◽  
Crumb Rubber ◽  
The Self ◽  
Acoustic Properties ◽  
Scrap Tires ◽  
Self Consolidating Concrete ◽  
Reduction Coefficient ◽  
Environmentally Sound

Several researches have been conducted to find a practical and environmentally sound solution of the problem of scrap tires. In this context, an experimental study was conducted to provide more data on the effect of crumb rubber on the acoustic properties of self-consolidating concrete SCC. To this end, Parallelepiped and cylindrical specimens were prepared by varying the proportion of crumb rubber with percentages of 0 %, 10 %, 20 % and 30 % of the volume of gravel. Properties such standardized level difference, sound absorption at different frequency and noise reduction were investigated. The results showed that the sound absorption and noise reduction coefficient were increased according to the increase of the percentage of crumb rubber. The self-consolidating concrete rubber SCCR has better acoustic properties in comparison with SCC.

Cascade Phase Lithic Technology: An Example from the Lower Snake River

1995 ◽  
Vol 16 (2) ◽  
pp. 95-115 ◽  
Author(s):  
William Andrefsky
Keyword(s):  
Raw Material ◽  
Coarse Grained ◽  
Stone Tool ◽  
Snake River ◽  
Projectile Points ◽  
Chipped Stone ◽  
Fine Grained ◽  
Technological Characteristics ◽  
Major River ◽  
River Drainages

Chipped stone artifact data from several Cascade phase sites located on the lower Snake River are analyzed to evaluate lithic technological characteristics of the early Cascade phase. Interpretations based upon the stone tool assemblages suggest traditional generalizations about the early Cascade phase require some rethinking. Specifically, tool type and debitage type analysis indicate that early Cascade phase settlement organization was not necessarily oriented to a local riverine setting, rather, early Cascade phase populations were highly mobile and visited major river drainages during only part of an annual cycle. Analysis of lithic raw material shows that early Cascade phase populations prefer nonlocally available cryptocrystalline cherts and fine grained basalt for production of refined tools such as projectile points and that locally available coarse grained basalts were primarily used to make nonportable situational gear.

Heat Treatment

2020 ◽  
Author(s):  
Patrick Schmidt
Keyword(s):  
Heat Treatment ◽  
Raw Materials ◽  
Middle Stone Age ◽  
Raw Material ◽  
Coarse Grained ◽  
Fine Grained ◽  
Heat Treated ◽  
Silica Rocks ◽  
People First ◽  
North And South America

In archaeology, heat treatment is the intentional transformation of stone (normally sedimentary silica rocks) by fire to produce materials with improved fracture properties. It has been documented on all continents, from the Africa Middle Stone Age up to subrecent times. It was an important part of the Mediterranean Neolithic and it sporadically appeared in the Paleolithc and Mesolithic of Asia and Europe. It may have been part of the knowledge of people first colonizing North and South America, and it played an important role for toolmaking in the Australian Prehistory. In all these contexts, heat treatment was normally used to improve the quality of stone raw materials for tool knapping; especially its association with pressure flaking has been highlighted, but a few examples also document the quest of making tools with improved qualities (sharper cutting edges) and intentional segmentation of large blocks of raw material to produce smaller, better-usable modules (fire fracturing). Two categories of silica rocks were most often heat-treated throughout prehistory: relatively fine-grained marine chert or flint and more coarse-grained continental silcrete. The finding of stone heat treatment in archaeological contexts opens up several research questions on its role for toolmaking, its cognitive and social implications, and the investment it required. Important venues for research are, for example: Why did people heat-treat stone? What happens to stones when heated? How can heating be recognized? By what technical means were stones heated? Which cost did heat treatment represent for its instigators? Answering these questions allows light to be shed on archaeologically relevant processes like innovation, reinvention, convergence, or the advent of complexity. The methods needed to produce these answers, however, often stem from other fields such as physics, chemistry, mineralogy, or material sciences.

scholarly journals Elongated hills near Schonhorst, Schleswig ­Holstein: Drumlins or terminal push-moraines?

1991 ◽  
Vol 38 ◽  
pp. 231-242
Author(s):  
J. A. Piotrowski ◽  
J. Vahldiek
Keyword(s):  
Detailed Analysis ◽  
Particle Orientation ◽  
Coarse Grained ◽  
Random Orientation ◽  
Thin Sections ◽  
Fine Grained ◽  
Geological Units ◽  
Weichselian Glaciation

Examination of bore-holes, test pitting and surficial mapping of one hill belonging to the group of smooth, elongated hills by Sch6nhorst, Schleswig-Holstein reveals three geological units: the lower, fine-grained, massive and compact till; the glaciofluvial sand; and the upper, coarse-grained, compact till with minute stringers and lenses of sand and silt. The sequence is strongly glaciotectonically disturbed. A detailed analysis of thin sections of the till micro-fabric, and of radiographs from undisturbed, oriented cores shows a relatively strong NE-SW and NW-SE particle orientation in the lower till and a weakly clustered to random orientation in the upper till. It is suggested that the field represents either drumlins (the more favourable hypothesis) or terminal push-moraines, formed during the first three ice advances of the Weichselian Glaciation.

Correlation between dislocation, grain boundary and interface of duplex SS in stress corrosion cracking(SCC)

1990 ◽  
Vol 48 (4) ◽  
pp. 928-929
Author(s):  
Wang Zheng-fang ◽  
Z.F. Wang
Keyword(s):  
Stainless Steel ◽  
Thermal Cycle ◽  
Secondary Phase ◽  
Corrosion Cracking ◽  
Coarse Grained ◽  
Test Environment ◽  
Fine Grained ◽  
Evaluation Test ◽  
Welding Thermal Cycle ◽  
Micro Analysis

The main purpose of this study highlights on the evaluation of chloride SCC resistance of the material,duplex stainless steel,OOCr18Ni5Mo3Si2 (18-5Mo) and its welded coarse grained zone(CGZ).18-5Mo is a dual phases (A+F) stainless steel with yield strength:512N/mm2 .The proportion of secondary Phase(A phase) accounts for 30-35% of the total with fine grained and homogeneously distributed A and F phases(Fig.1).After being welded by a specific welding thermal cycle to the material,i.e. Tmax=1350°C and t8/5=20s,microstructure may change from fine grained morphology to coarse grained morphology and from homogeneously distributed of A phase to a concentration of A phase(Fig.2).Meanwhile,the proportion of A phase reduced from 35% to 5-10°o.For this reason it is known as welded coarse grained zone(CGZ).In association with difference of microstructure between base metal and welded CGZ,so chloride SCC resistance also differ from each other.Test procedures:Constant load tensile test(CLTT) were performed for recording Esce-t curve by which corrosion cracking growth can be described, tf,fractured time,can also be recorded by the test which is taken as a electrochemical behavior and mechanical property for SCC resistance evaluation. Test environment:143°C boiling 42%MgCl2 solution is used.Besides, micro analysis were conducted with light microscopy(LM),SEM,TEM,and Auger energy spectrum(AES) so as to reveal the correlation between the data generated by the CLTT results and micro analysis.

scholarly journals Factors Affecting Acoustic Properties of Natural-Fiber-Based Materials and Composites: A Review

Textiles ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 55-85
Author(s):  
Tufail Hassan ◽  
Hafsa Jamshaid ◽  
Rajesh Mishra ◽  
Muhammad Qamar Khan ◽  
Michal Petru ◽  
...  
Keyword(s):  
Sound Absorption ◽  
Natural Fiber ◽  
Volume Fraction ◽  
Fiber Type ◽  
Alkali Treatment ◽  
Acoustic Properties ◽  
Synthetic Fiber ◽  
Sound Insulation ◽  
Factors Affecting ◽  
Wide Range

Recently, very rapid growth has been observed in the innovations and use of natural-fiber-based materials and composites for acoustic applications due to their environmentally friendly nature, low cost, and good acoustic absorption capability. However, there are still challenges for researchers to improve the mechanical and acoustic properties of natural fiber composites. In contrast, synthetic fiber-based composites have good mechanical properties and can be used in a wide range of structural and automotive applications. This review aims to provide a short overview of the different factors that affect the acoustic properties of natural-fiber-based materials and composites. The various factors that influence acoustic performance are fiber type, fineness, length, orientation, density, volume fraction in the composite, thickness, level of compression, and design. The details of various factors affecting the acoustic behavior of the fiber-based composites are described. Natural-fiber-based composites exhibit relatively good sound absorption capability due to their porous structure. Surface modification by alkali treatment can enhance the sound absorption performance. These materials can be used in buildings and interiors for efficient sound insulation.

scholarly journals Dual UV-Thermal Curing of Biobased Resorcinol Epoxy Resin-Diatomite Composites with Improved Acoustic Performance and Attractive Flame Retardancy Behavior

2021 ◽  
Vol 2 (1) ◽  
pp. 24-48
Author(s):  
Quoc-Bao Nguyen ◽  
Henri Vahabi ◽  
Agustín Rios de Anda ◽  
Davy-Louis Versace ◽  
Valérie Langlois ◽  
...  
Keyword(s):  
Heat Release ◽  
Flame Retardant ◽  
Epoxy Resin ◽  
Flame Retardancy ◽  
Sound Absorption ◽  
Flexural Modulus ◽  
Construction Materials ◽  
Acoustic Properties ◽  
Low Frequencies ◽  
Compacting Pressure

This study has developed novel fully bio-based resorcinol epoxy resin–diatomite composites by a green two-stage process based on the living character of the cationic polymerization. This process comprises the photoinitiation and subsequently the thermal dark curing, enabling the obtaining of thick and non-transparent epoxy-diatomite composites without any solvent and amine-based hardeners. The effects of the diatomite content and the compacting pressure on microstructural, thermal, mechanical, acoustic properties, as well as the flame behavior of such composites have been thoroughly investigated. Towards the development of sound absorbing and flame-retardant construction materials, a compromise among mechanical, acoustic and flame-retardant properties was considered. Consequently, the composite obtained with 50 wt.% diatomite and 3.9 MPa compacting pressure is considered the optimal composite in the present work. Such composite exhibits the enhanced flexural modulus of 2.9 MPa, a satisfying sound absorption performance at low frequencies with Modified Sound Absorption Average (MSAA) of 0.08 (for a sample thickness of only 5 mm), and an outstanding flame retardancy behavior with the peak of heat release rate (pHRR) of 109 W/g and the total heat release of 5 kJ/g in the pyrolysis combustion flow calorimeter (PCFC) analysis.

scholarly journals Balanced Sparsity for Efficient DNN Inference on GPU

2019 ◽  
Vol 33 ◽  
pp. 5676-5683 ◽  
Author(s):  
Zhuliang Yao ◽  
Shijie Cao ◽  
Wencong Xiao ◽  
Chen Zhang ◽  
Lanshun Nie
Keyword(s):  
Deep Neural Networks ◽  
General Purpose ◽  
Coarse Grained ◽  
Efficient Computation ◽  
Model Accuracy ◽  
Sparse Model ◽  
Model Inference ◽  
Fine Grained ◽  
Practical Inference ◽  
Speed Up

In trained deep neural networks, unstructured pruning can reduce redundant weights to lower storage cost. However, it requires the customization of hardwares to speed up practical inference. Another trend accelerates sparse model inference on general-purpose hardwares by adopting coarse-grained sparsity to prune or regularize consecutive weights for efficient computation. But this method often sacrifices model accuracy. In this paper, we propose a novel fine-grained sparsity approach, Balanced Sparsity, to achieve high model accuracy with commercial hardwares efficiently. Our approach adapts to high parallelism property of GPU, showing incredible potential for sparsity in the widely deployment of deep learning services. Experiment results show that Balanced Sparsity achieves up to 3.1x practical speedup for model inference on GPU, while retains the same high model accuracy as finegrained sparsity.

scholarly journals Submarine lava deltas of the 2018 eruption of Kīlauea volcano

2021 ◽  
Vol 83 (4) ◽  
Author(s):  
S. Adam Soule ◽  
Michael Zoeller ◽  
Carolyn Parcheta
Keyword(s):  
Grain Size ◽  
Pore Pressure ◽  
Mechanistic Model ◽  
Large Fraction ◽  
Volcanic Hazards ◽  
Lava Flows ◽  
Coarse Grained ◽  
Fine Grained ◽  
Fine Grain ◽  
Delta Formation

AbstractHawaiian and other ocean island lava flows that reach the coastline can deposit significant volumes of lava in submarine deltas. The catastrophic collapse of these deltas represents one of the most significant, but least predictable, volcanic hazards at ocean islands. The volume of lava deposited below sea level in delta-forming eruptions and the mechanisms of delta construction and destruction are rarely documented. Here, we report on bathymetric surveys and ROV observations following the Kīlauea 2018 eruption that, along with a comparison to the deltas formed at Pu‘u ‘Ō‘ō over the past decade, provide new insight into delta formation. Bathymetric differencing reveals that the 2018 deltas contain more than half of the total volume of lava erupted. In addition, we find that the 2018 deltas are comprised largely of coarse-grained volcanic breccias and intact lava flows, which contrast with those at Pu‘u ‘Ō‘ō that contain a large fraction of fine-grained hyaloclastite. We attribute this difference to less efficient fragmentation of the 2018 ‘a‘ā flows leading to fragmentation by collapse rather than hydrovolcanic explosion. We suggest a mechanistic model where the characteristic grain size influences the form and stability of the delta with fine grain size deltas (Pu‘u ‘Ō‘ō) experiencing larger landslides with greater run-out supported by increased pore pressure and with coarse grain size deltas (Kīlauea 2018) experiencing smaller landslides that quickly stop as the pore pressure rapidly dissipates. This difference, if validated for other lava deltas, would provide a means to assess potential delta stability in future eruptions.

scholarly journals A cooperative DDoS attack detection scheme based on entropy and ensemble learning in SDN

2021 ◽  
Vol 2021 (1) ◽  
Author(s):  
Shanshan Yu ◽  
Jicheng Zhang ◽  
Ju Liu ◽  
Xiaoqing Zhang ◽  
Yafeng Li ◽  
...  
Keyword(s):  
Ensemble Learning ◽  
Denial Of Service ◽  
Attack Detection ◽  
Coarse Grained ◽  
Communication Overhead ◽  
Detection Scheme ◽  
Fine Grained ◽  
Ddos Attack ◽  
Network Status ◽  
Ddos Attack Detection

AbstractIn order to solve the problem of distributed denial of service (DDoS) attack detection in software-defined network, we proposed a cooperative DDoS attack detection scheme based on entropy and ensemble learning. This method sets up a coarse-grained preliminary detection module based on entropy in the edge switch to monitor the network status in real time and report to the controller if any abnormality is found. Simultaneously, a fine-grained precise attack detection module is designed in the controller, and a ensemble learning-based algorithm is utilized to further identify abnormal traffic accurately. In this framework, the idle computing capability of edge switches is fully utilized with the design idea of edge computing to offload part of the detection task from the control plane to the data plane innovatively. Simulation results of two common DDoS attack methods, ICMP and SYN, show that the system can effectively detect DDoS attacks and greatly reduce the southbound communication overhead and the burden of the controller as well as the detection delay of the attacks.

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