WOOD-BASED SANDWICH PANELS: A REVIEW

A sandwich panel with a high ratio of strength to weight is commonly used in aerospace, construction, packaging and other fields. Using a renewable material such as wood to make sandwich panels can achieve a perfect unity of material and structure. In view of the lackof systematic analyses of wood-based sandwich panels, this work reviewed the developmentof wood-based sandwich panels. Based on the core structure, these panels can be divided into hollow-core structures and solid-core structures. With the emergence of new materials and new technologies, new wood-based sandwich products had been created. However, the current research only focused on the manufacturing, and the related novel design was still lacking. This work put forward a research idea of bionic designbased on the integration of structure and function and pointed out the research direction for wood-based sandwich panels.

Download Full-text

A numerical study of the impact perforation of sandwich panels with graded hollow sphere cores

Advances in Mechanical Engineering ◽

10.1177/16878140211009415 ◽

2021 ◽

Vol 13 (4) ◽

pp. 168781402110094

Author(s):

Ibrahim Elnasri ◽

Han Zhao

Keyword(s):

Boundary Conditions ◽

Hollow Sphere ◽

Sandwich Panel ◽

Numerical Study ◽

Sandwich Panels ◽

Hopkinson Bar ◽

Core Density ◽

The Core ◽

The Impact ◽

Force Displacement

In this study, we numerically investigate the impact perforation of sandwich panels made of 0.8 mm 2024-T3 aluminum alloy skin sheets and graded polymeric hollow sphere cores with four different gradient profiles. A suitable numerical model was conducted using the LS-DYNA code, calibrated with an inverse perforation test, instrumented with a Hopkinson bar, and validated using experimental data from the literature. Moreover, the effects of quasi-static loading, landing rates, and boundary conditions on the perforation resistance of the studied graded core sandwich panels were discussed. The simulation results showed that the piercing force–displacement response of the graded core sandwich panels is affected by the core density gradient profiles. Besides, the energy absorption capability can be effectively enhanced by modifying the arrangement of the core layers with unclumping boundary conditions in the graded core sandwich panel, which is rather too hard to achieve with clumping boundary conditions.

Download Full-text

Neoteric Fuzzy control stratagem and design of Chopper fed Multilevel Inverter for enhanced Voltage Output involving Plug-In Electric Vehicle (PEV) applications

Electronics ◽

10.3390/electronics8101092 ◽

2019 ◽

Vol 8 (10) ◽

pp. 1092 ◽

Cited By ~ 6

Author(s):

Sunddararaj ◽

Rangarajan ◽

Gopalan

Keyword(s):

Electric Vehicle ◽

New Technologies ◽

Control Strategies ◽

Economic Benefits ◽

Multilevel Inverter ◽

Control Logic ◽

Bidirectional Converters ◽

Hybrid Controller ◽

And Control ◽

Novel Design

The utilization of plug-in electric vehicles (PEV) has started to garner more attention worldwide considering the environmental and economic benefits. This has led to the invention of new technologies and motifs associated with batteries, bidirectional converters and inverters for Electric Vehicle applications. In this paper, a novel design and control of chopper circuit is proposed and configured with the series and parallel connection of the power electronic based switches for two-way operation of the converter. The bidirectional action of the proposed converter makes it suitable for plug-in electric vehicle applications as the grid is becoming smarter. The DC–DC converter is further interfaced with the designed multilevel inverter (MLI). The reduced switches associated with the novel design of MLI have overcome the cons associated with the conventional inverters in terms of enhanced performance in the proposed design. Further, novel control strategies have been proposed for the DC–DC converter based on Proportional Integral (PI) and Fuzzy based control logic. For the first time, the performance of the entire system is evaluated based on the comparison of proposed PI, fuzzy, and hybrid controllers. New rules have been formulated for the Fuzzy based controllers that are associated with the Converter design. This has further facilitated the interface of bidirectional DC–DC converter with the proposed MLI for an enhanced output voltage. The results indicate that the proposed hybrid controller provides better performance in terms of voltage gain, ripple, efficiency and overall aspects of power quality that forms the crux for PEV applications. The novelty of the design and control of the overall topology has been manifested based on simulation using MATLAB/SIMULINK.

Download Full-text

Prediction of Sound Transmission Loss for Finite Sandwich Panels Based on a Test Procedure on Beam Elements

Journal of Vibration and Acoustics ◽

10.1115/1.4023842 ◽

2013 ◽

Vol 135 (6) ◽

Cited By ~ 7

Author(s):

Zhongchang Qian ◽

Daoqing Chang ◽

Bilong Liu ◽

Ke Liu

Keyword(s):

Sandwich Panel ◽

Transmission Loss ◽

Test Procedure ◽

Sandwich Panels ◽

Sound Transmission ◽

Expansion Method ◽

Bending Stiffness ◽

Sound Transmission Loss ◽

Modal Expansion ◽

Beam Elements

An approach on the prediction of sound transmission loss for a finite sandwich panel with honeycomb core is described in the paper. The sandwich panel is treated as orthotropic and the apparent bending stiffness in two principal directions is estimated by means of simple tests on beam elements cut from the sandwich panel. Utilizing orthotropic panel theory, together with the obtained bending stiffness in two directions, the sound transmission loss of simply-supported sandwich panel is predicted by the modal expansion method. Simulation results indicated that dimension, orthotropy, and loss factor may play important roles on sound transmission loss of sandwich panel. The predicted transmission loss is compared with measured data and the agreement is reasonable. This approach may provide an efficient tool to predict the sound transmission loss of finite sandwich panels.

Download Full-text

Combining Hollow Core Photonic Crystal Fibers with Multimode, Solid Core Fiber Couplers through Arc Fusion Splicing for the Miniaturization of Nonlinear Spectroscopy Sensing Devices

Fibers ◽

10.3390/fib6040077 ◽

2018 ◽

Vol 6 (4) ◽

pp. 77 ◽

Cited By ~ 3

Author(s):

Hanna Stawska ◽

Maciej Popenda ◽

Elżbieta Bereś-Pawlik

Keyword(s):

Photonic Bandgap ◽

Average Power ◽

Fluorescence Emission ◽

Nonlinear Spectroscopy ◽

Fluorescence Emission Spectrum ◽

Solid Core ◽

Hollow Core ◽

Fluorescence Excitation ◽

Photonic Bandgap Fiber ◽

Sensing Applications

The presence of fiber optic devices, such as couplers or wavelength division multiplexers, based on hollow-core fibers (HCFs) is still rather uncommon, while such devices can be imagined to greatly increase the potential of HCFs for different applications, such as sensing, nonlinear optics, etc. In this paper, we present a combination of a standard, multimode fiber (MMF) optic coupler with a hollow core photonic bandgap fiber through arc fusion splicing and its application for the purpose of multiphoton spectroscopy. The presented splicing method is of high affordability due to the low cost of arc fusion splicers, and the measured splicing loss (SL) of the HCF-MMF splice is as low as (0.32 ± 0.1) dB, while the splice itself is durable enough to withstand a bending radius (rbend) of 1.8 cm. This resulted in a hybrid between the hollow core photonic bandgap fiber (HCPBF) and MMF coupler, delivering 20 mW of average power and 250-fs short laser pulses to the sample, which was good enough to test the proposed sensor setup in a simple, proof-of-concept multiphoton fluorescence excitation-detection experiment, allowing the successful measurement of the fluorescence emission spectrum of 10−5 M fluorescein solution. In our opinion, the presented results indicate the possibility of creating multi-purpose HCF setups, which would excel in various types of sensing applications.

Download Full-text

Influence of Technology on Socio-spatial City Development

Prostor ◽

10.31522/p.29.1(61).9 ◽

2021 ◽

Vol 29 (1 (61)) ◽

pp. 118-129

Author(s):

Ljiljana Vujadinović ◽

Svetlana K. Perović

Keyword(s):

Social Life ◽

New Technologies ◽

Spatial Dimension ◽

Social Changes ◽

Human Beings ◽

Spiritual Values ◽

City Development ◽

Material Goods ◽

And Function ◽

The City

This paper is studying influence of new technologies on city development with accent on socio-spatial dimension. The primary goal of the paper is to point out the reflections of earlier ideas in the context of modern technological processes in cities. All social, technical and technological components of a community, and finally civilization, are reflected within space of the city. Although having remained the greatest consumer of many material goods, city has also become a ‘’producer’’ of many technical-technological and spiritual values of civilization. Taking into account acceleration of phenomena in the world of technology and technology featuring modernity, it reasonably brings a question on realistic chance for prediction of their further course and related social changes that are about to cause it. In many scenarios of urban future, one can sense the idea of a city as a result of high technological achievements of civilization. Special attention is paid on informational city which, connecting a lot of people into systems of interactive information technology change the way of their mutual communication, as well as their social life and culture of behaviour. Measure of organization and function of city is set by telecommunication technologies, information, and computers. If city is a ‘’print of a society in space’’, then a contemporary moment refers to ‘’digitalization’’ of human beings, digitalization of their interactions, new aesthetics, value and other criteria. The tendency of this paper is to contribute to the understanding of new technologies on 21st century cities interpreted primarily through the prism of certain theoretical and experimental ideas and concepts of the 20th century.

Download Full-text

The Ontogeny and Function of Placental Macrophages

Frontiers in Immunology ◽

10.3389/fimmu.2021.771054 ◽

2021 ◽

Vol 12 ◽

Author(s):

Jake R. Thomas ◽

Praveena Naidu ◽

Anna Appios ◽

Naomi McGovern

Keyword(s):

Human Placenta ◽

Outer Layer ◽

New Technologies ◽

Placental Development ◽

Fetal Health ◽

Hofbauer Cells ◽

Recent Developments ◽

Placental Macrophages ◽

And Function ◽

Insight Into

The placenta is a fetal-derived organ whose function is crucial for both maternal and fetal health. The human placenta contains a population of fetal macrophages termed Hofbauer cells. These macrophages play diverse roles, aiding in placental development, function and defence. The outer layer of the human placenta is formed by syncytiotrophoblast cells, that fuse to form the syncytium. Adhered to the syncytium at sites of damage, on the maternal side of the placenta, is a population of macrophages termed placenta associated maternal macrophages (PAMM1a). Here we discuss recent developments that have led to renewed insight into our understanding of the ontogeny, phenotype and function of placental macrophages. Finally, we discuss how the application of new technologies within placental research are helping us to further understand these cells.

Download Full-text

Recent Patents on Bearing Pre-tightening

Recent Patents on Engineering ◽

10.2174/1872212115666210622145041 ◽

2021 ◽

Vol 15 ◽

Author(s):

Yanling Zhao ◽

Jiashuo Zhang

Keyword(s):

Research Direction ◽

Development Trend ◽

Machining Accuracy ◽

Processing Efficiency ◽

Tightening Force ◽

The Future ◽

Processing Accuracy ◽

And Function ◽

The Development Trend ◽

Accuracy Speed

Background: Bearing has been widely used in automotive, aerospace, electronics industry, and other fields.Its pre-tightening technology is one of the most critical technologies. It has an important influence on the accuracy, speed, stiffness, and temperature rise of the spindle. Proper pre-tightening force can eliminate bearing clearance and improve machining accuracy and efficiency of machine tools. Therefore, the development trend of bearing pre-tightening mechanism has been paid more and more attention. Objective: In order to improve the processing efficiency and processing accuracy of the bearing system, the structure and function of the bearing pre-tensioning device are continuously enhanced. Methods: This paper retraces various current representative patents relative to the mechanism of bearing pre-tightening. Results: Through the investigation of several patents of bearing pre-tightening devices, the principles and effects of different bearing pre-tightening devices are classified and reviewed. Besides, the future development trend of bearing pre-tightening devices is discussed. Conclusion: The optimization of the bearing pre-tightening device is conducive to improving processing efficiency and quality. A controllable pre-tightening force is the research direction, and more related patents will be invented in the future.

Download Full-text

States, Trends, and Future of Aquaponics Research

Sustainability ◽

10.3390/su12187783 ◽

2020 ◽

Vol 12 (18) ◽

pp. 7783

Author(s):

Yilong Hao ◽

Kai Ding ◽

Yaoyang Xu ◽

Yuting Tang ◽

Dong Liu ◽

...

Keyword(s):

Green Infrastructure ◽

Nutrient Management ◽

New Technologies ◽

Research Direction ◽

The United States ◽

Social Recognition ◽

Future Research ◽

System Construction ◽

Text Data ◽

Research Areas

As an environmentally-friendly aquaculture and planting system, aquaponics has attracted attention in various fields, such as fisheries, agriculture, and ecology. The existing review qualitatively described the development and challenges of aquaponics but lacked data support. This study selected 513 related documents (2000–2019) in the Web of Science database (WOS) to mine and quantitatively analyze its text data. The keyword co-occurrence network shows that the current aquaponics research mainly focuses on the system components, wastewater treatment, nutrient management, and system production. Research areas reflect obvious regional characteristics. China, the United States and Europe are dedicated to the application of new technologies, the optimization of system production, and the exploration of multiple roles. At present, the aquaponics development is facing many pressures from management and market. Future research requires more in-depth research in the system construction, nutrient management, and microbial community structure to provide a theoretical basis. Moreover, the identity construction within the conceptual framework of green infrastructure is a research direction worth exploring to solve low social recognition for aquaponics.

Download Full-text

Metaphors and other slippery creatures

The British Journal for the History of Science ◽

10.1017/s0007087419000438 ◽

2019 ◽

Vol 52 (2) ◽

pp. 345-352

Author(s):

James E. Strick

Keyword(s):

Cell Biology ◽

New Technologies ◽

Building Blocks ◽

State University ◽

Arizona State University ◽

Living Things ◽

History Of ◽

Dialectical Relationship ◽

Rich Material ◽

And Function

What are cells? How are they related to each other and to the organism as a whole? These questions have exercised biology since Schleiden and Schwann (1838–1839) first proposed cells as the key units of structure and function of all living things. But how do we try to understand them? Through new technologies like the achromatic microscope and the electron microscope. But just as importantly, through the metaphors our culture has made available to biologists in different periods and places. These two new volumes provide interesting history and philosophy of the development of cell biology. Reynolds surveys the field's changing conceptual structure by examining the varied panoply of changing metaphors used to conceptualize and explain cells – from cells as empty boxes, as building blocks, to individual organisms, to chemical factories, and through many succeeding metaphors up to one with great currency today: cells as social creatures in communication with others in their community. There is some of this approach in the Visions edited collection as well. But this collection also includes rich material on the technologies used to visualize cells and their dialectical relationship with the epistemology of the emerging distinct discipline of cell biology. This volume centres on, but is not limited to, ‘reflections inspired by [E.V.] Cowdry's [1924 volume] General Cytology’; it benefits from a conference on the Cowdry volume as well as a 2011 Marine Biological Lab/Arizona State University workshop on the history of cell biology.

Download Full-text

SANDWICH PANELS – BEHAVIOR IN FIRE BASED ON FIRE RESISTANCE TESTS

Applications of Structural Fire Engineering ◽

10.14311/asfe.2015.065 ◽

2016 ◽

Cited By ~ 3

Author(s):

Paweł Roszkowski ◽

Paweł Sulik

Keyword(s):

Thermal Insulation ◽

Fire Resistance ◽

Temperature Rise ◽

Sandwich Panel ◽

Sandwich Panels ◽

And Behavior ◽

In Fire ◽

Resistance Tests ◽

Building Elements

<p>Sandwich panel is the material that is easy and quickly to install. Basing on a great experience in the area of determination of the fire resistance class of construction building elements the authors describe the properties and behavior of building elements made of the sandwich panels exposed to fire. The article presents the results of fire resistance tests carried out in accordance with EN 1364-1 non-bearing walls made of sandwich panels with use of different cores.</p>The following parameters were analyzed: temperature rise on unexposed side (I – thermal insulation), integrity (E) depending on the orientations and on the width of the sandwich panels, deflection depending on the thickness of the boards. Conclusions were made on the base of the analysis from fire resistance tests.

Download Full-text