Experimental Evaluation of Tension and Shear Responses of Material Discontinuities in Origami-Based Sheet Metal Bending

Origami-based sheet metal (OSM) bending uses the origami concept to form a three-dimensional (3D) structures from a two-dimensional (2D) sheet by a series of bending operation. The OSM bending relies on a material discontinuity (MD) to perform the bending operation where the MDs are subjected to tension and shear load. Even though the OSM bending is a process that is simple, cost-effective, and easy to integrate into mass production, the understanding of the OSM bending mechanics is limiting its wide application. Particularly, the deformation behavior of MDs under tension and shear load remains unknown. Hence, this work investigates the response of MDs to these loads using the standard tension and shear tests. From the tests, critical values for two different ductile fracture criteria (DFC) are determined, and the possibility of a failure occurring in OSM bending is predicted. Results show that the load-bearing capability of the MDs is related to change in the effective cross-section area of a MD. Simple tension and shear tests can provide a simple procedure to predict failure in OSM bending. The impact of self-contact occurred under shear load influences maximum shear force and accuracy of failure prediction.

Electrical Characterization of Germanium Nanowires Using a Symmetric Hall Bar Configuration: Size and Shape Dependence

The fabrication of individual nanowire-based devices and their comprehensive electrical characterization remains a major challenge. Here, we present a symmetric Hall bar configuration for highly p-type germanium nanowires (GeNWs), fabricated by a top-down approach using electron beam lithography and inductively coupled plasma reactive ion etching. The configuration allows two equivalent measurement sets to check the homogeneity of GeNWs in terms of resistivity and the Hall coefficient. The highest Hall mobility and carrier concentration of GeNWs at 5 K were in the order of 100 cm2/(Vs) and 4×1019cm−3, respectively. With a decreasing nanowire width, the resistivity increases and the carrier concentration decreases, which is attributed to carrier scattering in the region near the surface. By comparing the measured data with simulations, one can conclude the existence of a depletion region, which decreases the effective cross-section of GeNWs. Moreover, the resistivity of thin GeNWs is strongly influenced by the cross-sectional shape.

Link Budget Analysis with Laser Energy for Time Transfer Using the Ajisai Satellite

Two-way Laser Time Transfer (TLTT) using the Ajisai satellite has been considered as a more accurate and stable time transfer technique than existing methods; TLTT requires the kHz laser pulses to decrease the systematic restrictions for TLTT realization. However, because of the low energy of the kHz laser pulses as well as the low cross section due to the small size of the Ajisai reflecting mirror, the link budget is an important issue to establish the TLTT link between two ground stations. In this study, the TLTT link budget is investigated to find the optimal laser pulse energy via analysis of geometric effects using 30 days of orbital data of the Ajisai satellite from 29 March 2021 within a ground network consisting of four stations located in three countries. The geometric configuration reduces the TLTT link budget by three orders of magnitude due to free space loss, atmospheric transmission, and effective cross section; then, the pulse energy is required to be much higher than laser ranging to the Ajisai satellite. It is shown from the simulation that a few tens of mJ level of pulse energy at the transmitting station is quite enough for TLTT realization.

Optimal Design of Magnetic Torque for a Hydraulic-Magnetic Rotary Hole Cleaning Tool in Horizontal Drilling

Summary The cleanliness of wellbore is a key factor in the drilling speed and quality of an oil field, especially in long horizontal sections of horizontal wells. Therefore, a hydraulic-magnetic rotary hole cleaning tool has been designed that does not rely on the rotary action of the drillpipe and could be used with a downhole motor to improve hole cleaning efficiency. However, the influence of magnet shape on the transmission of magnetic torque has remained unclear, such that the magnetic shaft transmission torque needed to be optimized to ensure efficient tool operation. In this study, magnetic field control equations were established in the region of the permanent magnet and air gap, and the magnetic flux distribution and magnetic torque generated between two magnetic axes in each field were calculated. Also, the influence of various magnetic field parameters on magnetic torque conduction of a strip magnet were compared and analyzed and then confirmed by comparison with experimental results. The results showed that the magnetic torque transmitted by strip magnets varied sinusoidally with magnetic axis deviation angles and that the highest torque was generated in the 12-pole model. However, the rate of increase in magnetic torque with magnet thickness was opposite to that of tile magnets, increasing with increasing magnet thickness. Magnetic torque variation with covered area was specific in the 6-pole model, showing a tendency of increasing and then decreasing. When magnet thickness was 12 mm and magnet coverage area in the effective cross section of the tool was 80%, the highest magnetic torque/unit volume of magnet was generated for achieving economic optimization. The results led to conclusions that, by solving the regional magnetic field, the magnetic torque change characteristics during movement of the magnetic drive mechanism of the hydraulic-magnetic rotary hole cleaning tool were simulated successfully and that these results could be used as an optimization analysis method for the magnetic drive mechanism of such tools.

Neutron-alpha reactions in nano α-Si3N4 particles by neutrons

Computer modeling was applied to the study of [Formula: see text] transmutations in [Formula: see text] nanoparticles under the influence of neutrons at different energies. The modeling was separately performed for each Si and N atoms in the [Formula: see text] nanoparticles and the effect of neutrons on transmutations was investigated. The simulations were conducted individually for each stable isotope due to different effective cross-section of the probability of transmutation in the different types of isotopes of silicon and nitrogen atoms. Effective cross-section spectra of [Formula: see text] transmutation in Si and N atoms were comparatively studied.

The study of neutron capture processes in AlN nanoparticles

The neutron capture processes in the AlN nanoparticles were investigated by computer modeling. Neutrons absorption were separately investigated for aluminum (Al) and nitrogen (N) atoms in the AlN nanoparticles. The modeling was performed separately for each stable Al and N isotopes, because the effective absorption cross-section of different types of isotopes of Al and N atoms is different. Moreover, effective cross-section spectra of neutron capture for aluminum and nitrogen atoms were comparatively investigated.

Analysis of shear stress on marine piles using shear friction theory

The current research investigation is focused on estimating the theoretical capacity of a rehabilitated steel marine pile. The old steel pile can be rehabilitated by installing new concrete encasement (jacket). The new concrete jacket can be easily connected to the old steel pile using shear friction between old pile and new concrete jacket or additional mechanical or welded connection. The under-water welding process is a very expensive task and considerable saving can be realized by eliminating this process. A previous experimental investigation was conducted to evaluate the behaviour of the rehabilitated steel pile. The maximum load and the load-slip deformation data were recorded for all of the tested specimens. The test results indicated that the marine pile can be efficiently rehabilitated by installing a concrete jacket using shear friction principles or the bolted connection to avoid the expense of welding under-water. The theoretical study included the investigation of surface friction, shear friction mechanism and cohesion on the bond capacity. The effect of the bolted anchor on increasing the effective cross section of the rehabilitated pile is examined. After investigating the predicted values of various equations developed by various researchers, the shear friction mechanical model developed by CSA 1994 is recommended to be used as the most effective formula that can provide an accurate prediction for the rehabilitated pile capacity.

Analysis of shear stress on marine piles using shear friction theory

The current research investigation is focused on estimating the theoretical capacity of a rehabilitated steel marine pile. The old steel pile can be rehabilitated by installing new concrete encasement (jacket). The new concrete jacket can be easily connected to the old steel pile using shear friction between old pile and new concrete jacket or additional mechanical or welded connection. The under-water welding process is a very expensive task and considerable saving can be realized by eliminating this process. A previous experimental investigation was conducted to evaluate the behaviour of the rehabilitated steel pile. The maximum load and the load-slip deformation data were recorded for all of the tested specimens. The test results indicated that the marine pile can be efficiently rehabilitated by installing a concrete jacket using shear friction principles or the bolted connection to avoid the expense of welding under-water. The theoretical study included the investigation of surface friction, shear friction mechanism and cohesion on the bond capacity. The effect of the bolted anchor on increasing the effective cross section of the rehabilitated pile is examined. After investigating the predicted values of various equations developed by various researchers, the shear friction mechanical model developed by CSA 1994 is recommended to be used as the most effective formula that can provide an accurate prediction for the rehabilitated pile capacity.

Elimination of Secondary Neutrons from Laser Proton-Boron Fusion

For low carbon energy generation, a very large exchange of electricity generators is existentially vital within the next number of years by power stations preferably at considerably low cost than the present installations. When considering the million times higher nuclear energy per reaction than chemical, the usual hydrogen fusion with abundant boron fuel is used for environmentally clean electricity generators. Instead of usually needed ignition temperatures of hundreds of million degrees Celsius, it is possible to use nonthermal ignition pressures from now available CPA laser pulses. In this non-LTE scheme, there is no need for high compression, the medium of hydrogen-boron-11 temperatures is low, and therefore the bremsstrahlung losses practically do not exist. The neutron, created by secondary reactions, elimination device includes tin and is arranged such that the neutrons are brought to nuclear reactions with the tin. We suggest adding the tin that has proven to be particularly advantageous because of its high effective cross section, and the neutron reactions with tin transform the tin nuclei into stable nuclei with a higher atomic weight.