Frequency stabilization of laser resonators using a new temperature-compensated piezo-mirror translator

1993 ◽  
Vol 71 (1-2) ◽  
pp. 25-28 ◽  
Author(s):  
H. El-Kashef
Keyword(s):  
Tensile Strength ◽  
High Voltage ◽  
Mechanical Stability ◽  
Low Cost ◽  
Frequency Stabilization ◽  
Laser Resonators ◽  
Compact Size ◽  
Adjustable Speed ◽  
Frequency Changes ◽  
High Mechanical Stability

For frequency stabilization and tuning of active and passive laser resonators, a new temperature-compensated piezo-mirror translator has been developed. It has compact size, high mechanical stability, high-voltage tensile strength, high adjustable speed, and low cost. It allows one to suppress, efficiently, frequency changes of laser resonators if a suitably high voltage is applied to it.

scholarly journals Metallic Nanowire Percolating Network: From Main Properties to Applications

2020 ◽  
Author(s):  
Daniel Bellet ◽  
Dorina T. Papanastasiou ◽  
Joao Resende ◽  
Viet Huong Nguyen ◽  
Carmen Jiménez ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Mechanical Stability ◽  
Low Cost ◽  
Transparent Electrodes ◽  
Energy Devices ◽  
Energy Technologies ◽  
New Generation ◽  
Industrial Demand ◽  
High Mechanical Stability ◽  
Percolating Network

There has been lately a growing interest into flexible, efficient and low-cost transparent electrodes which can be integrated for many applications. This includes several applications related to energy technologies (photovoltaics, lighting, supercapacitor, electrochromism, etc.) or displays (touch screens, transparent heaters, etc.) as well as Internet of Things (IoT) linked with renewable energy and autonomous devices. This associated industrial demand for low-cost and flexible industrial devices is rapidly increasing, creating a need for a new generation of transparent electrodes (TEs). Indium tin oxide has so far dominated the field of TE, but indium’s scarcity and brittleness have prompted a search into alternatives. Metallic nanowire (MNW) networks appear to be one of the most promising emerging TEs. Randomly deposited MNW networks, for instance, can present sheet resistance values below 10 Ω/sq., optical transparency of 90% and high mechanical stability under bending tests. AgNW or CuNW networks are destined to address a large variety of emerging applications. The main properties of MNW networks, their stability and their integration in energy devices are discussed in this contribution.

scholarly journals Reconstruction after Subtotal Sacrectomy for Sacral Ewing’s Sarcoma Using Tibial Allograft Strut Grafting: A Case Report

2021 ◽  
pp. 296-302
Author(s):  
Ryosuke Hirota ◽  
Makoto Emori ◽  
Yoshinori Terashima ◽  
Kousuke Iba ◽  
Noriyuki Iesato ◽  
...  
Keyword(s):  
Surgical Treatment ◽  
Ewing’S Sarcoma ◽  
Mechanical Stability ◽  
Ewing's Sarcoma ◽  
Lumbar Vertebrae ◽  
Iliac Screws ◽  
Sacral Tumor ◽  
Sacral Resection ◽  
High Mechanical Stability ◽  
Rectal Dysfunction

We present the case of a 15-year-old girl. Two months after becoming aware of pain, she was diagnosed with a sacral tumor and referred to our department. She was diagnosed with a sacral Ewing’s sarcoma; after chemotherapy, it was determined that the tumor could be resected, so surgical treatment was performed. The sacrum and ilium were partially resected at the lower end of S1, and the lumbar vertebrae and pelvis were fixed with a pedicle screw and two iliac screws on each side of L3, and the sacral resection was reconstructed with a tibial strut allograft. No tumor recurrence or metastasis has been observed 1 year postoperatively. She developed bladder and rectal dysfunction, but she remained independent in activities of daily living and her daily life was not limited. The bone fusion in the reconstructed area confirmed the lack of instrumentation looseness. Surgical treatment for sacral Ewing’s sarcoma was performed to cure the patient. We believe that the tibial allograft contributed to the patient’s ability to walk on her own due to its high mechanical stability. Postoperative bone healing was observed with the same material, suggesting that the tibial allograft is useful for similar procedures.

scholarly journals Innovative Polymeric Hybrid Nanocomposites for Application in Photocatalysis

Polymers ◽  
2021 ◽  
Vol 13 (8) ◽  
pp. 1184
Author(s):  
Maria Cantarella ◽  
Giuliana Impellizzeri ◽  
Alessandro Di Mauro ◽  
Vittorio Privitera ◽  
Sabrina Carola Carroccio
Keyword(s):  
Hybrid Systems ◽  
Hybrid Materials ◽  
Large Scale ◽  
Mechanical Stability ◽  
Low Cost ◽  
Atomic Layer ◽  
Hybrid Nanocomposites ◽  
Polymeric Nanocomposites ◽  
Wastewater Remediation ◽  
Antibacterial Performance

The immobilization of inorganic nanomaterials on polymeric substrates has been drawing a lot of attention in recent years owing to the extraordinary properties of the as-obtained materials. The hybrid materials, indeed, combine the benefits of the plastic matter such as flexibility, low-cost, mechanical stability and high durability, with them deriving from their inorganic counterparts. In particular, if the inorganic fillers are nanostructured photocatalysts, the originated hybrid systems will be able to utilize the energy delivered by light, catalysing chemical reactions in a sustainable pathway. Most importantly, since the nanofillers can be ad-hoc anchored to the macromolecular structure, their release in the environment will be prevented, thus overcoming one of the main restrictions that impedes their applications on a large scale. In this review, several typologies of hybrid photocatalytic nanomaterials, obtained by using both organic and inorganic semiconductors and realized with different synthetic protocols, were reported and discussed. In the first part of the manuscript, nanocomposites realized by simply blending the TiO2 or ZnO nanomaterials in thermoplastic polymeric matrices are illustrated. Subsequently, the atomic layer deposition (ALD) technique is presented as an excellent method to formulate polymeric nanocomposites. Successively, some examples of polyporphyrins hybrid systems containing graphene, acting as photocatalysts under visible light irradiation, are discussed. Lastly, photocatalytic polymeric nanosponges, with extraordinary adsorption properties, are shown. All the described materials were deeply characterized and their photocatalytic abilities were evaluated by the degradation of several organic water pollutants such as dyes, phenol, pesticides, drugs, and personal care products. The antibacterial performance was also evaluated for selected systems. The relevance of the obtained results is widely overviewed, opening the route for the application of such multifunctional photocatalytic hybrid materials in wastewater remediation.

scholarly journals Properties of Low-Cost WPCs Made from Alien Invasive Trees and rLDPE for Interior Use in Social Housing

Polymers ◽  
2021 ◽  
Vol 13 (15) ◽  
pp. 2436
Author(s):  
Abubakar Sadiq Mohammed ◽  
Martina Meincken
Keyword(s):  
Tensile Strength ◽  
Water Absorption ◽  
Social Housing ◽  
Low Cost ◽  
Production Costs ◽  
Low Density Polyethylene ◽  
Low Grade ◽  
Low Density ◽  
Invasive Trees ◽  
Recycled Low Density Polyethylene

Low-cost wood–plastic composites (WPCs) were developed from invasive trees and recycled low-density polyethylene. The aim was to produce affordable building materials for low-cost social housing in South Africa. Both raw materials are regarded as waste materials, and the subsequent product development adds value to the resources, while simultaneously reducing the waste stream. The production costs were minimised by utilising the entire biomass of Acacia saligna salvaged from clearing operations without any prior processing, and low-grade recycled low-density polyethylene to make WPCs without any additives. Different biomass/plastic ratios, particle sizes, and press settings were evaluated to determine the optimum processing parameters to obtain WPCs with adequate properties. The water absorption, dimensional stability, modulus of rupture, modulus of elasticity, tensile strength, and tensile moduli were improved at longer press times and higher temperatures for all blending ratios. This has been attributed to the crystallisation of the lignocellulose and thermally induced cross-linking in the polyethylene. An increased biomass ratio and particle size were positively correlated with water absorption and thickness swelling and inversely related with MOR, tensile strength, and density due to an incomplete encapsulation of the biomass by the plastic matrix. This study demonstrates the feasibility of utilising low-grade recycled polyethylene and the whole-tree biomass of A. saligna, without the need for pre-processing and the addition of expensive modifiers, to produce WPCs with properties that satisfy the minimum requirements for interior cladding or ceiling material.

scholarly journals A 300-GHz low-cost high-gain fully metallic Fabry–Perot cavity antenna for 6G terahertz wireless communications

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Basem Aqlan ◽  
Mohamed Himdi ◽  
Hamsakutty Vettikalladi ◽  
Laurent Le-Coq
Keyword(s):  
Communication Systems ◽  
Low Cost ◽  
Frequency Selective Surface ◽  
High Gain ◽  
Wireless Communication Systems ◽  
Beam Radiation ◽  
Compact Size ◽  
Fabry Perot ◽  
Operating Bandwidth ◽  
Polarization Level

AbstractA low-cost, compact, and high gain Fabry–Perot cavity (FPC) antenna which operates at 300 GHz is presented. The antenna is fabricated using laser-cutting brass technology. The proposed antenna consists of seven metallic layers; a ground layer, an integrated stepped horn element (three-layers), a coupling layer, a cavity layer, and an aperture-frequency selective surface (FSS) layer. The proposed aperture-FSS function acts as a partially reflective surface, contributing to a directive beam radiation. For verification, the proposed sub-terahertz (THz) FPC antenna prototype was developed, fabricated, and measured. The proposed antenna has a measured reflection coefficient below − 10 dB from 282 to 304 GHz with a bandwidth of 22 GHz. The maximum measured gain observed is 17.7 dBi at 289 GHz, and the gain is higher than 14.4 dBi from 285 to 310 GHz. The measured radiation pattern shows a highly directive pattern with a cross-polarization level below − 25 dB over the whole band in all cut planes, which confirms with the simulation results. The proposed antenna has a compact size, low fabrication cost, high gain, and wide operating bandwidth. The total height of the antenna is 1.24 $${\lambda }_{0}$$ λ 0 ($${\lambda }_{0}$$ λ 0 at the design frequency, 300 GHz) , with a size of 2.6 mm × 2.6 mm. The proposed sub-THz waveguide-fed FPC antenna is suitable for 6G wireless communication systems.

scholarly journals Development of an Additive Manufacturing System for the Deposition of Thermoplastics Impregnated with Carbon Fibers

2019 ◽  
Vol 3 (2) ◽  
pp. 35 ◽  
Author(s):  
Miguel Reis Silva ◽  
António M. Pereira ◽  
Nuno Alves ◽  
Gonçalo Mateus ◽  
Artur Mateus ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Additive Manufacturing ◽  
Carbon Fibers ◽  
Low Cost ◽  
Deposition Process ◽  
Processing Parameters ◽  
Yarn Diameter ◽  
Thermoplastic Matrix ◽  
Anisotropic Mechanical Properties ◽  
Long Carbon Fiber

This work presents an innovative system that allows the oriented deposition of continuous fibers or long fibers, pre-impregnated or not, in a thermoplastic matrix. This system is used in an integrated way with the filamentary fusion additive manufacturing technology and allows a localized and oriented reinforcement of polymer components for advanced engineering applications at a low cost. To demonstrate the capabilities of the developed system, composite components of thermoplastic matrix (polyamide) reinforced with pre-impregnated long carbon fiber (carbon + polyamide), 1 K and 3 K, were processed and their tensile and flexural strength evaluated. It was demonstrated that the tensile strength value depends on the density of carbon fibers present in the composite, and that with the passage of 2 to 4 layers of fibers, an increase in breaking strength was obtained of about 366% and 325% for the 3 K and 1 K yarns, respectively. The increase of the fiber yarn diameter leads to higher values of tensile strength of the composite. The obtained standard deviation reveals that the deposition process gives rise to components with anisotropic mechanical properties and the need to optimize the processing parameters, especially those that lead to an increase in adhesion between deposited layers.

Micro Palm and Kenaf Fibers Reinforced PLA Composite: Effect of Volume Fraction on Tensile Strength

2011 ◽  
Vol 145 ◽  
pp. 1-5 ◽  
Author(s):  
K.W. Neoh ◽  
Kim Yeow Tshai ◽  
P.S. Khiew ◽  
Chin Hua Chia
Keyword(s):  
Tensile Strength ◽  
Mechanical Stability ◽  
Volume Fraction ◽  
Environmental Concern ◽  
Raw Materials ◽  
Kenaf Fiber ◽  
Composite Effect ◽  
Fiber Loading ◽  
Biodegradable Composite ◽  
Kenaf Fibers

Extensive environmental concern associated with the disposal of solid plastic wastes has stirred tremendous interest in the production and use of sustainable biodegradable polymers. Among the vast variety of available materials, Polylactic Acid (PLA) standout as the most commercially viable mass produced resin to date. However, its low thermal and mechanical stability, excessive brittleness, and relatively higher cost have led to numerous research efforts in producing biodegradable polymer composite filled with natural organic fibers. This paper describes the preparation and the mechanical characteristics of a compression molded biodegradable composite made entirely of renewable raw materials. The composites were reinforced with pulverized palm, kenaf and alkali (1M NaOH:fiber in ratio 2:1) treated kenaf fibers, at a fiber mass proportion of 20 to 60% blended PLA and processed in a custom-built compression mold. SEM microscan revealed that the kenaf fiber has a mean diameter of 40μm, length 1236.6μm, and aspect ratio of 31 while the measured values for palm fiber was 58.7μm, 1041.2μm, and 17.7, respectively. All resulting composites showed significant enhancement in tensile strength. At 20, 40 and 60% fiber loading, the palm/PLA composite recorded tensile strength increment of 46.9, 47.8 and 36.6%, respectively. For the kenaf/PLA composite, greatest improvement was achieved at 40% fiber loading with alkali treated kenaf, with approximately 54% higher than the neat PLA while only 12.6% was recorded for the non-treated kenaf/PLA composite, signifying that the surface modification greatly improved fiber-matrix adhesion. SEM observations on the fracture surface showed similar findings. Compared to commercially available palm/Polypropylene (palm/PP) composite at 50% fiber loading, our measured tensile strength for the PLA composite loaded with 40% alkali treated kenaf fiber was still about 20% lower. Further enhancement in the mechanical characteristic of the kenaf/PLA composite is required to push for its wider utilization in the polymer industry.

High Voltage Subsea Pump – A Low Cost Subsea Boosting Enabler

2017 ◽  
Author(s):  
A. Margarida ◽  
J. Pimentel ◽  
E. Thibaut ◽  
E. Cardoso
Keyword(s):  
High Voltage ◽  
Low Cost
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