scholarly journals Design and analysis of 3D-printed hybrid couplers for D-band applications

2021 ◽  
pp. 1-8
Author(s):  
K. Lomakin ◽  
L. Klein ◽  
G. Gold
Keyword(s):  
Frequency Range ◽  
Band Frequency ◽  
Uv Curable ◽  
Sources Of Uncertainty ◽  
Phase Errors ◽  
Phase Deviation ◽  
3D Printed ◽  
Slotted Waveguide ◽  
Electroless Silver Plating ◽  
The Impact

Abstract This work focuses on the impact of the build orientation on additively manufactured waveguide-based hybrid couplers for D-band frequency range and relates it to other sources of uncertainty within the overall manufacturing process and measurement instrumentation for the D-band frequency range. The designed specimens are first printed from UV curable photopolymer resin and subsequently metal coated by an electroless silver plating process, which in turn is improved by making use of the slotted waveguide approach. Although the requirements toward geometrical precision to achieve phase errors below 10° are in an order of 0.1 mm, a desktop grade DLP printer is utilized in this work in order to point out the prospects and limitations of additive manufacturing. Furthermore, waveguide paths with bends are part of the model and their impact on the measured attenuation is estimated explicitly. Despite this narrow field of tolerances, one specimen could have been realized, which achieves a measured output magnitude imbalance of 0.7 dB over the frequency range from 120 to 155 GHz while at the same time exhibiting a phase deviation of only <10° from the desired 90°. With these demonstrated results, the proposed approach provides suitability for future applications in the D-band frequency range.

scholarly journals Characteristic Mode Analysis Based X-Band Defected Dodecagonal Patch Antenna

2019 ◽  
Vol 9 (1) ◽  
pp. 3216-3220
Keyword(s):  
Microstrip Antenna ◽  
Return Loss ◽  
Mode Analysis ◽  
Center Frequency ◽  
Frequency Range ◽  
Characteristic Mode ◽  
Resonant Frequencies ◽  
Band Frequency ◽  
X Band ◽  
The Impact

A defected dodecagonal microstrip antenna fed through co-planar waveguide and operating in X-band frequency range(8-12 GHz) is proposed. Characteristic mode analysis is employed in examining the impact of defects on the resonant frequencies and return loss. Contrast in return loss for the suggested antenna with and without defects is dealt through Characteristic mode Analysis. Geometrical aspects of the proposed antenna are 40 mm × 35.5 mm × 0.1 mm. Subtrate material used in design is FR4 with a dielectric constant (εr ) = 4.4 and height (h) = 0.1m. CST Microwave Studio is used to simulate antenna parameters and Characteristic mode analysis. A return loss of -49.5dB at center frequency of 10.12GHz is observed with a fractional bandwidth of 47.6%. Gain of the antenna peaks at 4 dBi in the band of operation.

Bone tissue engineering in the greater omentum with computer-aided design/computer-aided manufacturing scaffolds is enhanced by a periosteum transplant

2020 ◽  
Author(s):  
Hendrik Naujokat ◽  
Klaas Loger ◽  
Juliane Schulz ◽  
Yahya Açil ◽  
Jörg Wiltfang
Keyword(s):  
Bone Formation ◽  
Bone Tissue ◽  
Computer Aided Design ◽  
Bone Tissue Regeneration ◽  
Histological Evaluation ◽  
Greater Omentum ◽  
Collagen Membrane ◽  
Computer Aided ◽  
3D Printed ◽  
The Impact

Aim: This study aimed to evaluate two different vascularized bone flap scaffolds and the impact of two barrier membranes for the reconstruction of critical-size bone defects. Materials & methods: 3D-printed scaffolds of biodegradable calcium phosphate and bioinert titanium were loaded with rhBMP-2 bone marrow aspirate, wrapped by a collagen membrane or a periosteum transplant and implanted into the greater omentum of miniature pigs. Results: Histological evaluation demonstrated significant bone formation within the first 8 weeks in both scaffolds. The periosteum transplant led to enhanced bone formation and a homogenous distribution in the scaffolds. The omentum tissue grew out a robust vascular supply. Conclusion: Endocultivation using 3D-printed scaffolds in the greater omentum is a very promising approach in defect-specific bone tissue regeneration.

scholarly journals Aspects of Strength Testing of Tank Containers in Compliance with the Requirements of the UN Navigation Rules and Regulations

2021 ◽  
Vol 9 (3) ◽  
pp. 349
Author(s):  
Andrii Sulym ◽  
Pavlo Khozia ◽  
Eduard Tretiak ◽  
Václav Píštěk ◽  
Oleksij Fomin ◽  
...  
Keyword(s):  
Natural Frequencies ◽  
Response Spectrum ◽  
Experimental Curve ◽  
Bulk Liquid ◽  
Frequency Range ◽  
Test Configuration ◽  
Shock Response ◽  
Shock Response Spectrum ◽  
Spectrum Curve ◽  
The Impact

This article deals with the method of computer-aided studies of the results of tank container impact tests to confirm the ability of portable tanks and multi-element gas containers to withstand the impact in the longitudinal direction on a specially equipped test rig or using a railway flat car by impacting a flat car with a striking car, in compliance with the requirements of the UN Navigation Rules and Regulations. It is shown that the main assessed characteristic of the UN requirements is the spectrum of the shock response (accelerations) for the interval natural frequencies of the shock pulse. The calculation of the points of the shock response spectrum curve based on the test results is reproduced in four stages. A test configuration of the impact testing of the railway flat car with a tank container is presented, and the impact is performed in such a way that, under a single impact, the shock spectrum curve obtained during the tests for both fittings subjected to impact repeats or exceeds the minimum shock spectrum curve for all frequencies in the range of 2 Hz to 100 Hz. Formulas for determining the relative displacements and accelerations for the interval natural frequencies of the shock wave are given. The research results are presented in graphical form, indicating that the experimental values of the shock response spectrum exceed the minimum permissible values; the equation of the experimental curve of the shock response spectrum in the frequency range 0–100 Hz is described by power-law dependence. The coefficients of the equation were determined by the statistical method of maximum likelihood with the determination factor being 0.897, which is a satisfactory value; a comparative analysis showed that the experimental curve of the impact response spectrum in the frequency range 0–100 Hz exceeds the normalized curve, which confirms compliance with regulatory requirements. A new test configuration is proposed using a tank car with a bulk liquid, the processes in which upon impact differ significantly from other freight wagons under longitudinal impact loads of the tank container. The hydraulic impact resulting from the impact on the tank container and the platform creates an overturning moment that causes the rear fittings to be unloaded.

scholarly journals Buoyancy control in ammonoid cephalopods refined by complex internal shell architecture

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
David J. Peterman ◽  
Kathleen A. Ritterbush ◽  
Charles N. Ciampaglio ◽  
Erynn H. Johnson ◽  
Shinya Inoue ◽  
...  
Keyword(s):  
Surface Tension ◽  
Water Retention Capacity ◽  
Functional Explanation ◽  
Retention Capacity ◽  
Biomechanical Stress ◽  
Liquid Retention ◽  
3D Printed ◽  
Functional Explanations ◽  
Hydrophilic Coatings ◽  
The Impact

AbstractThe internal architecture of chambered ammonoid conchs profoundly increased in complexity through geologic time, but the adaptive value of these structures is disputed. Specifically, these cephalopods developed fractal-like folds along the edges of their internal divider walls (septa). Traditionally, functional explanations for septal complexity have largely focused on biomechanical stress resistance. However, the impact of these structures on buoyancy manipulation deserves fresh scrutiny. We propose increased septal complexity conveyed comparable shifts in fluid retention capacity within each chamber. We test this interpretation by measuring the liquid retained by septa, and within entire chambers, in several 3D-printed cephalopod shell archetypes, treated with (and without) biomimetic hydrophilic coatings. Results show that surface tension regulates water retention capacity in the chambers, which positively scales with septal complexity and membrane capillarity, and negatively scales with size. A greater capacity for liquid retention in ammonoids may have improved buoyancy regulation, or compensated for mass changes during life. Increased liquid retention in our experiments demonstrate an increase in areas of greater surface tension potential, supporting improved chamber refilling. These findings support interpretations that ammonoids with complex sutures may have had more active buoyancy regulation compared to other groups of ectocochleate cephalopods. Overall, the relationship between septal complexity and liquid retention capacity through surface tension presents a robust yet simple functional explanation for the mechanisms driving this global biotic pattern.

scholarly journals Development of a schwarzite-based moving bed 3D printed water treatment system for nanoplastic remediation

RSC Advances ◽  
2021 ◽  
Vol 11 (32) ◽  
pp. 19788-19796
Author(s):  
Bramha Gupta ◽  
Rushikesh S. Ambekar ◽  
Raphael M. Tromer ◽  
Partha Sarathi Ghosal ◽  
Rupal Sinha ◽  
...  
Keyword(s):  
Water Treatment ◽  
Aquatic Ecosystem ◽  
Treatment System ◽  
Environmental Challenges ◽  
Moving Bed ◽  
Water Treatment System ◽  
3D Printed ◽  
The Impact

The impact of micro and nanoplastic debris on our aquatic ecosystem is among the most prominent environmental challenges we face today.

scholarly journals The High-Rate Sealed MRPC to Promote Pollutant Exchange in Gas Gaps: Status on the Development and Observations

2021 ◽  
Vol 11 (11) ◽  
pp. 4722
Author(s):  
Botan Wang ◽  
Xiaolong Chen ◽  
Yi Wang ◽  
Dong Han ◽  
Baohong Guo ◽  
...  
Keyword(s):  
Gas Flow ◽  
High Rate ◽  
Stable Operation ◽  
Beam Test ◽  
High Luminosity ◽  
Rate Test ◽  
3D Printed ◽  
Resistive Plate Chambers ◽  
The Impact ◽  
Current Behavior

This work reports the latest observations on the behavior of two Multigap Resistive Plate Chambers (MRPC) under wide high-luminosity exposures, which motivate the development and in-beam test of the sealed MRPC prototype assembled with low-resistive glass. The operation currently being monitored, together with previous simulation results, shows the impact of gas pollution caused by avalanches in gas gaps, and the necessity to shrink the gas-streaming volume. With the lateral edge of the detector sealed by a 3D-printed frame, a reduced gas-streaming volume of ~170 mL has been achieved for a direct gas flow to the active area. A high-rate test of the sealed MRPC prototype shows that, ensuring a 97% efficiency and 70 ps time resolution, the sealed design results in a stable operation current behavior at a counting rate of 3–5 kHz/cm2. The sealed MRPC will become a potential solution for future high luminosity applications.

scholarly journals DESIGN OF CARTESIAN FEEDBACK RF POWER AMPLIFIER FOR L-BAND FREQUENCY RANGE

2008 ◽  
Vol 2 ◽  
pp. 207-222 ◽  
Author(s):  
Jit Singh Mandeep ◽  
Anand Lokesh ◽  
Syed Idris Syed Hassan ◽  
mohd nazri Mahmud ◽  
Mohd Fadzil Ain
Keyword(s):  
Power Amplifier ◽  
Rf Power ◽  
Frequency Range ◽  
Band Frequency ◽  
Rf Power Amplifier ◽  
L Band

scholarly journals Methods For Calculating Radio Holograms Of Volumetric Objects

2020 ◽  
Vol 12 (4) ◽  
pp. 429-436
Author(s):  
Valery A. Golunov ◽  
◽  
Vadim A. Korotkov ◽  
Keyword(s):  
Point Sources ◽  
Real Point ◽  
Two Dimensional ◽  
Frequency Range ◽  
Satisfactory Accuracy ◽  
Phase Errors ◽  
Sphere Radius ◽  
Virtual Point ◽  
Volumetric Objects

A method for calculating holograms for volumetric objects based on the representation of objects in the form of ensembles of virtual point sources distributed on a set of parallel planes has been proposed. The proposed method is the development of the well-known method in which objects are represented as ensemble of real point scatterers. The possibilities of the proposed method are demonstrated by calculating a hologram of a fragment of a sphere, on which 1000 points are randomly selected, at which radiation emanating from the center of the sphere is scattered. The choice of a fragment of a sphere as an object under study is due to the fact that when calculating its hologram, phase errors inherent in approximate calculations are most pronounced. The calculations were performed for the frequency range of 2...100 GHz, the sphere radius of 0.5 m, a two-dimensional hologram size of 0.65×0.65 m, and a pixel count of 512×512. It is shown that, in comparison with the known method, the proposed method makes it possible to calculate the amplitude of a hologram with satisfactory accuracy if virtual sources are placed on parallel planes in an amount of more than 64 pieces. In the case of objects that require representation in the form of an ensemble of point scatterers in the amount of more than 1000 pieces, the calculation of their holograms by the proposed method turns out to be much more efficient than the known method.

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