The authors thank Mr. Wu, MS Sun, Mr. Wang, Mr. Mu, and Mr. Li for their help. This study was supported by the China Postdoctoral Science Foundation (2022M721604) and the Wenzhou Key Science and Technology Tackling Programmer (ZG2023015).

1. Model
NOTE: Due to the complex structure of the ring main unit (Figure 1A), an online design software was chosen to simplify the operation of the ring main unit.
<ol>
	<li>Modelling simplification
	<ol>
		<li>Partially simplify the model, preserving the air box section of the RMU while removing or simplifying other components such as insulating shafts, fastening bolts, nuts, sealing components, and pressure support brackets. The simplified version is shown in (Figure 1B).
		<ol>
			<li>In the process of simplifying the 630A type ring main unit, remove the insulated shaft connecting the circuit breaker room with the instrument box and many fixed bolts and nuts. Take out the sealing parts and pressure-retaining bracket and connect the static contacts of the isolated static beam with the lower branch busbar under the premise of ensuring that the whole setup has the same conductive current and only the vacuum circuit breaker, the circuit breaker fixing plate, and the static contacts and the vacuum circuit breaker are retained.</li>
			<li>Retain only the vacuum circuit breaker, circuit breaker fixing plate, static contact, and vacuum circuit breaker blocking plate. Overall, remove bolts and gaskets from the model, fill the holes after removing the bolts with solids, reduce the number of mesh parts, and optimize the irregular shapes of the parts. Remove instruments for panel operation, mounting plates, brackets, and other operating parts, such as instrument boxes, that have no effect on the temperature rise simulation process.</li>
			<li>Remove the insulated housings of some components can be disregarded under simulation as they have little effect on the simulation results. In addition, grounding switches that have no effect on the use of the equipment during normal operation remove them, and retain the circuit breaker room for simulation.</li>
		</ol>
		</li>
		<li>To delete any section, simply select it and click on the Delete option.</li>
	</ol>
	</li>
</ol>
2. Eddy field solution
<ol>
	<li>Pre-processing settings 
	NOTE: The Eddy current field emulation is the basis for performing the temperature field solution, which requires the subsequent analysis of the solved heat source as a load on the temperature field.
	<ol>
		<li>Refer to the equipment documentation for the ring main unit and the relevant manuals to gather information on the physical properties and parameters of each component of the ring main unit. Set the physical attributes and parameters of the ring main unit components in Maxwell based on the information obtained, as detailed in Table 1.</li>
		<li>Set the eddy current field load current at 630 A with a frequency of 50 Hz. In the Maxwell software, select One Side of the Upper and Lower Outgoing Arms, enter the excitation module, and set the current magnitude to 630 A. In the solution settings section, choose a frequency of 50 Hz. 
		NOTE: In a ring main unit&#39;s conductive circuit, the pathway formed by all the components from the upper outlet arm to the lower outlet arm is known as the phase sequence. Therefore, in this paper, the phases A, B, and C are arranged from left to right.</li>
		<li>The material parameters of the components of the ring main unit are shown in Table 2.</li>
		<li>Direct the current through the outgoing line arms, flexible connections, busbars, circuit breakers, static contact support busbars, and branch busbars for each phase. The aim is to realize a current path that allows the components to complete the load.</li>
		<li>Utilize Maxwell&#39;s adaptive meshing to complete grid control for the model. Use the Maxwell adaptive mesh partitioning method for larger components and the local mesh refinement for smaller internal components. 
		NOTE: Maxwell can continuously enhance grid precision during the solving process, eliminating the need to click Mesh Operations for additional mesh partitioning.</li>
		<li>Set the solution step size. Click on Analysis in the model tree, open the Solve Step settings, and set the Maximum Number of Passes to 10. Keep other settings at their default values without making any changes.</li>
	</ol>
	</li>
	<li>Principle of Eddy current field calculation15,16.
	<ol>
		<li>Use Maxwell&#39;s first equation, which describes the action of charge on the generation of an electric field17. 
		<img alt="Equation 1" src="/files/ftp_upload/66643/66643eq01.jpg" style="margin: auto;" />&#160; &#160; &#160;(1) 
		where&#160;&#961; represents the charge density; &#949;0 represents the vacuum dielectric constant.</li>
		<li>Use Maxwell&#39;s second equation, which describes the relationship between a changing magnetic field and an electric field and the effect of a magnetic field on the motion of a charge. 
		<img alt="Equation 2" src="/files/ftp_upload/66643/66643eq02.jpg" style="margin: auto;" />&#160; &#160; &#160;(2) 
		where <img alt="Equation 3" src="/files/ftp_upload/66643/66643eq03.jpg" style="margin: auto;" />&#160;represents the magnetic field strength. This equation describes that a varying magnetic field produces a vortex electric field, i.e., the spin of the vortex electric field is equal to the negative of the rate of change of the magnetic field with time.</li>
		<li>Use Maxwell&#39;s third equation, which describes the effect of magnetic charge on the production of a magnetic field. 
		<img alt="Equation 4" src="/files/ftp_upload/66643/66643eq04.jpg" style="margin: auto;" />&#160; &#160; &#160;(3) 
		This equation describes the magnetic field produced by a magnetic charge as being passive, i.e., there are no monopoles in the magnetic field.</li>
		<li>Use Maxwell&#39;s fourth equation, which describes the relationship between a varying electric field and a magnetic field and the effect of an electric current on a magnetic field. 
		<img alt="Equation 5" src="/files/ftp_upload/66643/66643eq05.jpg" style="margin: auto;" />&#160; &#160; &#160;(4) 
		where <img alt="Equation 6" src="/files/ftp_upload/66643/66643eq06.jpg" style="margin: auto;" /> represents the current density and&#160;&#956;0 represents the vacuum permeability. This equation describes that a varying electric field produces a vortex magnetic field, i.e., the spin of the vortex magnetic field is equal to the sum of the current density and the rate of change of the electric field with time.</li>
		<li>Based on the above equations, use the Maxwell 3D using Eddy current solver module to solve the ohmic loss generated by the conductive circuit in the RMU, which provides a heat source for the subsequent thermal simulation analysis. Its mathematical expression is given as18 
		<img alt="Equation 7" src="/files/ftp_upload/66643/66643eq07.jpg" style="margin: auto;" />&#160; &#160; &#160;(5) 
		where&#160;&#963; denotes the conductivity of the conducting loop material; J is the current density in the loop.</li>
	</ol>
	</li>
	<li>Calculation results
	<ol>
		<li>Click on the Maxwell 3D option in the interface and open the validation check to review all settings for errors. If there are no errors, proceed to click Analyze All to initiate the solving process.</li>
		<li>Utilize Maxwell&#39;s post-processing Calculator to compute and plot the ohmic losses in the Eddy current field of the ring main unit, as shown in Table 3.</li>
	</ol>
	</li>
</ol>
3. Temperature field solution
NOTE: For comparative purposes, divide the temperature field into Icepak and steady state thermal. Set up and solve each separately to achieve a comparative analysis.
<ol>
	<li>Icepak model setup
	<ol>
		<li>Set the material properties as follows: designate all circuit solid materials as Cu-Pure, with surfaces using Cu-polished-surface. For the panel components, select Aluminum6061-T6 material, with a surface coating of Paint-AL surface with an emissivity of 0.35. See Table 4 for details. Right-click on the Selected Component, click Edit and then go to Properties to set the material for both the surface and solid materials.</li>
		<li>Select the model and click on Set in the Edit menu, then choose Multilevel Meshing Level to adjust the mesh settings. Set the external cabinet to a mesh level of 2, and all boundaries to a mesh level of 2. For all other components, set the mesh level to 3. Finally, open Mesh control and click Generate to create the mesh.</li>
		<li>To ensure the accuracy and efficiency of the simulation regardless of the grid size, validation of grid independence is necessary. Import the geometric model of the temperature field enclosure, established using the design software for meshing.</li>
		<li>As depicted in Figure 2, the polarization curves of the four grid sets are well-aligned. At a working voltage of 0.5 V, the current densities for the four grid sets are 2.357 A/cm2, 2.358 A/cm2, 2.356 A/cm2, and 2.454 A/cm2, respectively, with the error between the maximum and current densities being less than 1%. To balance efficiency and accuracy, determine the grid size which comes to be 987924.</li>
	</ol>
	</li>
	<li>Solution setup
	<ol>
		<li>Set the directions of the solution domain Cabinet to Opening.</li>
		<li>In the software, select Problem Step. Under Basic Parameters, check the Surface-to-Surface Radiation Model, choose Zero Equation for Turbulent Flow Regime, select the Gravity option for Natural Convection, and set the ambient temperature to 20 &#176;C.</li>
		<li>In the File settings, choose Volumetric Heat Losses for EM Mapping and select All Objects Shown to complete the loss settings.</li>
	</ol>
	</li>
	<li>Temperature field calculation
	<ol>
		<li>In icepak, apply three main conservation equations for energy: mass conservation equation, momentum conservation equation, and energy conservation equation. Specifically, use the momentum conservation equation, which is as follows19: 
		<img alt="Equation 8" src="/files/ftp_upload/66643/66643eq08.jpg" style="margin: auto;" />&#160; &#160; &#160;(6) 
		Energy Conservation Equation: 
		<img alt="Equation 9" src="/files/ftp_upload/66643/66643eq09.jpg" style="margin: auto;" />&#160; &#160; &#160;(7) 
		Mass conservation equations: 
		<img alt="Equation 10" src="/files/ftp_upload/66643/66643eq10.jpg" style="margin: auto;" />&#160; &#160; &#160;(8) 
		Energy transfer equation for heat transfer from a solid heat source: 
		<img alt="Equation 11" src="/files/ftp_upload/66643/66643eq11.jpg" style="margin: auto;" />&#160; &#160; &#160;(9) 
		&#961;&#160;represents the density of the fluid; v represents the flow velocity vector; T represents the temperature; p is the pressure; &#964; is the viscous force on the surface of the micro metabolite;&#160;&#954; is the heat transfer coefficient; Sh is the body heat source; h is the specific enthalpy of the fluid and F is the body force of the micro metabolite. 
		NOTE: The results of the temperature field calculations are shown in Figure 3A and Figure 4A.</li>
	</ol>
	</li>
	<li>Steady-state thermal model setup
	<ol>
		<li>Maintain the material properties as per Table 3 in the material settings. Generate the ohmic losses resulting from the eddy current field simulation analysis in the Steady State Thermal module by clicking on Thermal Load generation.</li>
		<li>Click on the Convective Temperature Value and set it to 20 &#176;C, with a convective coefficient of 5 (W/m&#178;&#176;C) applied to the inner walls of the cabinet, components, and external cabinet. Apply the settings and generate. Set the output to solve for temperature by clicking on Solve &#62; Output Results. 
		NOTE: The main temperature field governing equations in the steady-state thermal temperature field calculation20,21,22 principle is usually derived from the law of heat conduction (Fourier&#39;s law of heat conduction). In the one-dimensional case, the temperature field heat transfer equation can be expressed as20: 
		<img alt="Equation 12" src="/files/ftp_upload/66643/66643eq12.jpg" style="margin: auto;" />&#160; &#160; &#160;(10) 
		In this equation, T represents the temperature inside the object, t is time, x&#160;is spatial coordinates, and&#160;&#945; is the thermal diffusivity. This equation describes the variation of temperature with respect to time and space, where the right side expresses the relationship between heat conduction rate and temperature gradient. In a more general three-dimensional scenario, the heat conduction equation for the temperature field can be expressed in the following form: 
		<img alt="Equation 13" src="/files/ftp_upload/66643/66643eq13.jpg" style="margin: auto;" />&#160; &#160; &#160;(11) 
		&#961;&#160;represents the density of the object, c is the specific heat capacity, K is the thermal conductivity and Q is the heat source term within the volume. This equation describes the variation of the temperature field, influenced by heat conduction, heat sources, and thermal capacitance.</li>
		<li>The temperature field calculation results are shown in Figure 3. Compare the temperature values summarized in Table 5 and Table 6.</li>
	</ol>
	</li>
</ol>

A Comprehensive Approach to Investigate RMU Temperature Rise Problem

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The authors do not have any conflicting interests.

This paper is a comparative simulation analysis of the temperature rise of the ring cabinet based on engineering modeling software and finite element software, and the most suitable solution for the actual temperature rise situation is analyzed by two finite element temperature field solution modules. Thermal management is also described in Icoz23 as a critical and essential component in maintaining the high efficiency and reliability of electronic components. The significance of conducting a comp...

The ring main unit is a group of high-voltage switchgear mounted in a steel metal cabinet or made of assembled spaced ring network power supply unit of electrical equipment. The overall structure of the load switch and conductive circuit consists of the conductive circuit, which includes a number of components comprising the main core of the ring unit. However, due to its compact internal structure, the ring main unit faces challenges in heat dissipation. This can lead to thermal deformation and aging when operating for extended periods in high-temperature environments. These issues not only affect the service life of the unit but also impact its insulating properties, posing safety risks. In particular, equipment damage and electrical accidents become more likely, posing significant safety hazards.
Within different research areas, scholars have conducted a series of studies on the temperature rise of overhead line switchgear and analyzed various factors affecting the temperature distribution1. In Polykrati et al.2, a mathematical model for the estimation of the temperature rise of components installed on the distribution network during a short-circuit fault is presented. The model was applied to the common disconnecting switches of the network, and the characteristics of the results were plotted according to the different forms of the asymmetrical part of the short-circuit current waveform and the initial value of the short-circuit DC current component. Guan et al., on the other hand, have taken into account the contact resistance and electromagnetic repulsion by building an equivalent contact bridge to simulate the contact interface and further analyzed the electromagnetic-thermal coupling field and temperature rise experiment3. In addition, the researchers investigated the temperature field and thermal stress distribution of the dynamic and static contacts inside the ring main unit by finite element simulation, which provided a basis for the study of circuit breaker life4. Finally, Mueller et al. have focused on the geometrical characteristics of heat sinks and evaluated the effects of material selection, total surface area, temperature uniformity, and maximum surface temperature on thermal performance5. These studies provide valuable insights and methods to improve switchgear performance and reliability, reduce temperature rise, and extend equipment life. Wang et al. proposed a MiNET Deep Learning Model (MDLM) in the UPIOT environment with the purpose of detecting fault diagnosis of electrical ring cabinets, which was validated to have an identification accuracy of 99.1%, which is significantly higher than that of other methods6. Lei et al. studied the thermal performance of a GIS busbar in a steady state using the magneto-fluid-thermal coupling analysis method, thereby optimizing the conductor and tank diameter based on the temperature rise simulation results7. Ouerdani et al. used the RMU temperature rise simulation model to determine the temperature rise at critical locations inside it, thereby fixing the duration of the maximum overload for the components inside the RMU accordingly8. Zheng et al. described a conventional rectangular busbar in a model of high-current switchgear by building a two-dimensional model and applying the finite element method (FEM) for electromagnetic field calculations. It enabled them to obtain the distribution of bus conductor current density and power loss. An irregular busbar was designed after considering the effects of proximity effect and skin effect. This irregular busbar design improved the performance of conventional rectangular busbar9.
As for the aspect of using the icepak simulation, Wang et al. carried out a temperature rise simulation through vortex field, airflow field, and temperature field theories and found that the temperature rise of the ring main unit was more serious under natural convection. They successfully reduced the temperature rise level by adding forced air cooling and making improvements to the internal contact structure10. Zhu et al.11 used the icepak to simulate a thermal model in order to compare the effect of the presence of thermal vias on the PCB and the presence of heat sinks on the temperature of the power devices. Finally, the theoretical analysis is compared with the simulation results to verify the correctness of the theoretical analysis. Mao et al.12 studied the temperature and internal airflow distribution under summer operating conditions by thermal simulation based on the CAE software in the icepak simulation. The problem of how to improve the cooling efficiency and control the temperature rise of multiple silver-plated contacts is given, and the temperature and internal airflow contours captured in the simulation will lay the foundation for the design of the cooling scheme for the six silver-plated contacts mounted in the sealing unit. Conversely, in the use of a steady-state thermal module, Zhang13 Modeling methods are discussed for solving the thermal network of a high-pressure bushing using an alternative transient procedure. Test and simulation results are in good agreement with the thermal steady state and transient states of the bushing. The transient results are then used to evaluate the bushing overload capacity. Vaimann et al.14 developed and analyzed an analytical thermal model of a synchronous reluctance motor for predicting the temperature of its different components and the set total parameter thermal network.
With the continuous advancement of research on electrical equipment such as ring main units, conventional temperature rise tests, and production methods are relatively inefficient. Therefore, by utilizing finite element technology combined with offline tests, not only the design cost issues are addressed, but adjustments and optimizations can be promptly made to real-world problems based on simulations. Based on the research progress mentioned above, the use of ANSYS Icepak and Steady-state thermal coupling for comparative analysis is rarely mentioned. Therefore, the protocol describes the mechanism research of finite elements, uses numerical and morphological combinations to establish a finite element temperature rise simulation model for the enclosure, and discusses the finite element temperature rise simulation model based on the results of the two analytical modules by comparing the results of the two simulation modules. Through the comparison between the two simulation modules, we will get the characteristics of the temperature rise trend of the ring main unit and find the most applicable method so as to provide the necessary basis and research ideas for a strategy to mitigate the temperature rise of the ring main unit.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Air</td>
			<td>/</td>
			<td>/</td>
			<td>Conventional gases</td>
		</tr>
		<tr>
			<td>Aluminum</td>
			<td>/</td>
			<td>/</td>
			<td>Alloy Materials</td>
		</tr>
		<tr>
			<td>Copper</td>
			<td>/</td>
			<td>/</td>
			<td>Alloy Materials</td>
		</tr>
		<tr>
			<td>Icepak</td>
			<td>ANSYS company</td>
			<td>ANSYS 2021R1</td>
			<td>A CFD thermal simulation software</td>
		</tr>
		<tr>
			<td>PC hosting</td>
			<td>/</td>
			<td>12th Generation Intel(R) Core(TM) i5-13500F CPU</td>
			<td>Host computer equipment</td>
		</tr>
		<tr>
			<td>SolidWorks</td>
			<td>Subsidiary of Dassault Systemes</td>
			<td>SolidWorks2021</td>
			<td>An engineering software drawing tool</td>
		</tr>
		<tr>
			<td>Steady-state thermal</td>
			<td>ANSYS company</td>
			<td>ANSYS 2021R1</td>
			<td>A thermal simulation solution tool</td>
		</tr>
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comparative study of simulation of temperature rise in ring main unit

The Ring Main Unit (RMU) is a critical device in power distribution systems used for connecting and distributing electricity. However, due to its compact internal structure and high current load, heat dissipation issues are particularly prominent. To address this problem, this study innovatively proposes a simplified RMU model, employing finite element simulation methods to accurately solve for the ohmic losses of conductors under actual operating conditions and obtain ohmic loss data for various components. This is the first in-depth investigation of the RMU's temperature rise problem using such a comprehensive approach. Subsequently, the temperature field was solved using two different temperature field analysis modules, with a detailed comparison and analysis of the simulation results to identify similarities, differences, and trends in temperature distribution. The results indicate that the temperature field solution model, which considers convective heat transfer, is more accurate and aligns with actual operating conditions. This research provides an innovative approach and practical solutions for the design and optimization of RMUs. Future research can further explore multiphysics coupling analysis methods to address structural design and mandatory validation issues for high and ultra-high voltage RMUs and other electrical equipment, thereby providing important insights for engineering design.

Based on the data in Table 3, the following conclusions can be drawn: The overall losses for Phases A, B, and C are relatively similar. Specifically, the total losses for Phase A are 16.063 W/m&#179;, Phase B is 16.12 W/m&#179;, and Phase C is 19.57 W/m&#179;. The locations with higher losses may be at the connections of various components. This is mainly because contact resistance and conductor resistance typically exist at these connection points. When current passes through these connections, signific...

Author Spotlight: Simulation and Analysis of the Temperature Rise of Ring Main Unit Equipment

This paper addresses the temperature rise problem of the ring main unit by establishing a simplified model and conducting a comparative analysis in two temperature field-solving modules.

Comparative Study of Simulation of Temperature Rise in Ring Main Unit

The Ring Main Unit (RMU) is a critical device in power distribution systems used for connecting and distributing electricity. However, due to its compact ...

comparative-study-of-simulation-of-temperature-rise-in-ring-main-unit

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1.5K Views.  Wenzhou University. This paper addresses the temperature rise problem of the ring main unit by establishing a simplified model and conducting a comparative analysis in two temperature field-solving modules.

Video: Author Spotlight: Simulation and Analysis of the Temperature Rise of Ring Main Unit Equipment

Simulation, Fabrication and Characterization of THz Metamaterial Absorbers

Metamaterials (MM), artificial materials engineered to have properties that may not be found in nature, have been widely explored since the first theoretical1 and experimental demonstration2 of their unique properties. MMs can provide a highly controllable electromagnetic response, and to date have been demonstrated in every technologically relevant spectral range including the optical3, near IR4, mid IR5 , THz6 , mm-wave7 , microwave8 and radio9 bands. Applications include perfect lenses10, sensors11, telecommunications12, invisibility cloaks13 and filters14,15. We have recently developed single band16, dual band17 and broadband18 THz metamaterial absorber devices capable of greater than 80% absorption at the resonance peak. The concept of a MM absorber is especially important at THz frequencies where it is difficult to find strong frequency selective THz absorbers19. In our MM absorber the THz radiation is absorbed in a thickness of ~ &lambda;/20, overcoming the thickness limitation of traditional quarter wavelength absorbers. MM absorbers naturally lend themselves to THz detection applications, such as thermal sensors, and if integrated with suitable THz sources (e.g. QCLs), could lead to compact, highly sensitive, low cost, real time THz imaging systems.

This protocol outlines the simulation, fabrication and characterization of THz metamaterial absorbers. Such absorbers, when coupled with an appropriate sensor, have applications in THz imaging and spectroscopy.

Metamaterials (MM),  artificial materials engineered to have properties that may not be found in  nature, have been widely explored since the first ...

Simulation of the Planetary Interior Differentiation Processes in the Laboratory

A planetary interior is under high-pressure and high-temperature conditions and it has a layered structure. There are two important processes that led to that layered structure, (1) percolation of liquid metal in a solid silicate matrix by planet differentiation, and (2) inner core crystallization by subsequent planet cooling. We conduct high-pressure and high-temperature experiments to simulate both processes in the laboratory. Formation of percolative planetary core depends on the efficiency of melt percolation, which is controlled by the dihedral (wetting) angle. The percolation simulation includes heating the sample at high pressure to a target temperature at which iron-sulfur alloy is molten while the silicate remains solid, and then determining the true dihedral angle to evaluate the style of liquid migration in a crystalline matrix by 3D visualization. The 3D volume rendering is achieved by slicing the recovered sample with a focused ion beam (FIB) and taking SEM image of each slice with a FIB/SEM crossbeam instrument. The second set of experiments is designed to understand the inner core crystallization and element distribution between the liquid outer core and solid inner core by determining the melting temperature and element partitioning at high pressure. The melting experiments are conducted in the multi-anvil apparatus up to 27 GPa and extended to higher pressure in the diamond-anvil cell with laser-heating. We have developed techniques to recover small heated samples by precision FIB milling and obtain high-resolution images of the laser-heated spot that show melting texture at high pressure. By analyzing the chemical compositions of the coexisting liquid and solid phases, we precisely determine the liquidus curve, providing necessary data to understand the inner core crystallization process.

The high-pressure and high-temperature experiments described here mimic planet interior differentiation processes. The processes are visualized and better understood by high-resolution 3D imaging and quantitative chemical analysis.

A planetary interior is under high-pressure and high-temperature conditions and it has a layered structure. There are two important processes that led to ...

Laboratory Drop Towers for the Experimental Simulation of Dust-aggregate Collisions in the Early Solar System

For the purpose of investigating the evolution of dust aggregates in the early Solar System, we developed two vacuum drop towers in which fragile dust aggregates with sizes up to ~10 cm and porosities up to 70% can be collided. One of the drop towers is primarily used for very low impact speeds down to below 0.01 m/sec and makes use of a double release mechanism. Collisions are recorded in stereo-view by two high-speed cameras, which fall along the glass vacuum tube in the center-of-mass frame of the two dust aggregates. The other free-fall tower makes use of an electromagnetic accelerator that is capable of gently accelerating dust aggregates to up to 5 m/sec. In combination with the release of another dust aggregate to free fall, collision speeds up to ~10 m/sec can be achieved. Here, two fixed high-speed cameras record the collision events. In both drop towers, the dust aggregates are in free fall during the collision so that they are weightless and match the conditions in the early Solar System.

We present a technique to achieve low-velocity to intermediate-velocity collisions between fragile dust aggregates in the laboratory. For this purpose, two vacuum drop-tower setups have been developed that allow collision velocities between &#60;0.01 and ~10 m/sec. The collision events are recorded by high-speed imaging.

For the purpose of investigating the evolution of dust aggregates in the early Solar System, we developed two vacuum drop towers in which fragile dust ...

Writing and Low-Temperature Characterization of Oxide Nanostructures

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions. Oxide interfaces exhibit a wide range of properties that can be controlled include conduction, piezoelectric behavior, ferromagnetism, superconductivity and nonlinear optical properties. Recently, methods for controlling these properties at extreme nanoscale dimensions have been discovered and developed. Here are described explicit step-by-step procedures for creating LaAlO3/SrTiO3 nanostructures using a reversible conductive atomic force microscopy technique. The processing steps for creating electrical contacts to the LaAlO3/SrTiO3 interface are first described. Conductive nanostructures are created by applying voltages to a conductive atomic force microscope tip and locally switching the LaAlO3/SrTiO3 interface to a conductive state. A versatile nanolithography toolkit has been developed expressly for the purpose of controlling the atomic force microscope (AFM) tip path and voltage. Then, these nanostructures are placed in a cryostat and transport measurements are performed. The procedures described here should be useful to others wishing to conduct research in oxide nanoelectronics.

Oxide nanostructures provide new opportunities for science and technology. The interfacial conductivity between LaAlO3 and SrTiO3 can be controlled with near-atomic precision using a conductive atomic force microscopy technique. The protocol for creating and measuring conductive nanostructures at LaAlO3/SrTiO3 interfaces is demonstrated.

Oxide nanoelectronics is a rapidly growing field which seeks to develop novel materials with multifunctional behavior at nanoscale dimensions.  Oxide ...

Simulation of Human-induced Vibrations Based on the Characterized In-field Pedestrian Behavior

For slender and lightweight structures, vibration serviceability is a matter of growing concern, often constituting the critical design requirement. With designs governed by the dynamic performance under human-induced loads, a strong demand exists for the verification and refinement of currently available load models. The present contribution uses a 3D inertial motion tracking technique for the characterization of the in-field pedestrian behavior. The technique is first tested in laboratory experiments with simultaneous registration of the corresponding ground reaction forces. The experiments include walking persons as well as rhythmical human activities such as jumping and bobbing. It is shown that the registered motion allows for the identification of the time variant pacing rate of the activity. Together with the weight of the person and the application of generalized force models available in literature, the identified time-variant pacing rate allows to characterize the human-induced loads. In addition, time synchronization among the wireless motion trackers allows identifying the synchronization rate among the participants. Subsequently, the technique is used on a real footbridge where both the motion of the persons and the induced structural vibrations are registered. It is shown how the characterized in-field pedestrian behavior can be applied to simulate the induced structural response. It is demonstrated that the in situ identified pacing rate and synchronization rate constitute an essential input for the simulation and verification of the human-induced loads. The main potential applications of the proposed methodology are the estimation of human-structure interaction phenomena and the development of suitable models for the correlation among pedestrians in real traffic conditions.

A protocol is presented for the characterization of the in-field pedestrian behavior and the simulation of the resulting structural response. Field-tests demonstrate that the in situ identified pacing rate and synchronization rate among the participants constitute an essential input for the simulation and verification of the human-induced loads.

For slender and lightweight structures, vibration serviceability is a matter of growing concern, often constituting the critical design requirement. With ...

Knowledge Based Cloud FE Simulation of Sheet Metal Forming Processes

The use of Finite Element (FE) simulation software to adequately predict the outcome of sheet metal forming processes is crucial to enhancing the efficiency and lowering the development time of such processes, whilst reducing costs involved in trial-and-error prototyping. Recent focus on the substitution of steel components with aluminum alloy alternatives in the automotive and aerospace sectors has increased the need to simulate the forming behavior of such alloys for ever more complex component geometries. However these alloys, and in particular their high strength variants, exhibit limited formability at room temperature, and high temperature manufacturing technologies have been developed to form them. Consequently, advanced constitutive models are required to reflect the associated temperature and strain rate effects. Simulating such behavior is computationally very expensive using conventional FE simulation techniques.
This paper presents a novel Knowledge Based Cloud FE (KBC-FE) simulation technique that combines advanced material and friction models with conventional FE simulations in an efficient manner thus enhancing the capability of commercial simulation software packages. The application of these methods is demonstrated through two example case studies, namely: the prediction of a material's forming limit under hot stamping conditions, and the tool life prediction under multi-cycle loading conditions.

The following paper presents a novel FE simulation technique (KBC-FE), which reduces computational cost by performing simulations on a cloud computing environment, through the application of individual modules. Moreover, it establishes a seamless collaborative network between world leading scientists, enabling the integration of cutting edge knowledge modules into FE simulations.

The use of Finite Element (FE) simulation software to adequately predict the outcome of sheet metal forming processes is crucial to enhancing the ...

Measurement of Quantum Interference in a Silicon Ring Resonator Photon Source

Silicon photonic chips have the potential to realize complex integrated quantum information processing circuits, including photon sources, qubit manipulation, and integrated single-photon detectors. Here, we present the key aspects of preparing and testing a silicon photonic quantum chip with an integrated photon source and two-photon interferometer. The most important aspect of an integrated quantum circuit is minimizing loss so that all of the generated photons are detected with the highest possible fidelity. Here, we describe how to perform low-loss edge coupling by using an ultra-high numerical aperture fiber to closely match the mode of the silicon waveguides. By using an optimized fusion splicing recipe, the UHNA fiber is seamlessly interfaced with a standard single-mode fiber. This low-loss coupling allows the measurement of high-fidelity photon production in an integrated silicon ring resonator and the subsequent two-photon interference of the produced photons in a closely integrated Mach-Zehnder interferometer. This paper describes the essential procedures for the preparation and characterization of high-performance and scalable silicon quantum photonic circuits.

Silicon photonic chips have the potential to realize complex integrated quantum systems. Presented here is a method for preparing and testing a silicon photonic chip for quantum measurements.

Silicon photonic chips have the potential to realize complex integrated quantum information processing circuits, including photon sources, qubit ...

Fabrication of Nanopillar-Based Split Ring Resonators for Displacement Current Mediated Resonances in Terahertz Metamaterials

Terahertz (THz) split ring resonator (SRR) metamaterials (MMs) has been studied for gas, chemical, and biomolecular sensing applications because the SRR is not affected by environmental characteristics such as the temperature and pressure surrounding the resonator. Electromagnetic radiation in THz frequencies is biocompatible, which is a critical condition especially for the application of the biomolecular sensing. However, the quality factor (Q-factor) and frequency responses of traditional thin-film based split ring resonator (SRR) MMs are very low, which limits their sensitivities and selectivity as sensors. In this work, novel nanopillar-based SRR MMs, utilizing displacement current, are designed to enhance the Q-factor up to 450, which is around 45 times higher than that of traditional thin-film-based MMs. In addition to the enhanced Q-factor, the nanopillar-based MMs induce a larger frequency shifts (17 times compared to the shift obtained by the traditional thin-film based MMs). Because of the significantly enhanced Q-factors and frequency shifts as well as the property of biocompatible radiation, the THz nanopillar-based SRR are ideal MMs for the development of biomolecular sensors with high sensitivity and selectivity without inducing damage or distortion to biomaterials. A novel fabrication process has been demonstrated to build the nanopillar-based SRRs for displacement current mediated THz MMs. A two-step gold (Au) electroplating process and an atomic layer deposition (ALD) process are used to create sub-10 nm scale gaps between Au nanopillars. Since the ALD process is a conformal coating process, a uniform aluminum oxide (Al2O3) layer with nanometer-scale thickness can be achieved. By sequentially electroplating another Au thin film to fill the spaces between Al2O3 and Au, a close-packed Au-Al2O3-Au structure with nano-scale Al2O3 gaps can be fabricated. The size of the nano-gaps can be well defined by precisely controlling the deposition cycles of the ALD process, which has an accuracy of 0.1 nm.

A protocol for the design and fabrication of a novel nanopillar-based split ring resonator (SRR) is presented.

Terahertz (THz) split ring resonator (SRR) metamaterials (MMs) has been studied for gas, chemical, and biomolecular sensing applications because the SRR ...

Study of Siphon Breaker Experiment and Simulation for a Research Reactor

Under the design conditions of a research reactor, the siphon phenomenon induced by pipe rupture can cause continuous outward flow of water. To prevent this outflow, a control device is required. A siphon breaker is a type of safety device that can be utilized to control the loss of coolant water effectively.
To analyze the characteristics of siphon breaking, a real-scale experiment was conducted. From the results of the experiment, it was found that there are several design factors that affect the siphon breaking phenomenon. Therefore, there is a need to develop a theoretical model capable of predicting and analyzing the siphon breaking phenomenon under various design conditions. Using the experimental data, it was possible to formulate a theoretical model that accurately predicts the progress and the result of the siphon breaking phenomenon. The established theoretical model is based on fluid mechanics and incorporates the Chisholm model to analyze two-phase flow. From Bernoulli&#39;s equation, the velocity, quantity, undershooting height, water level, pressure, friction coefficient, and factors related to the two-phase flow could be obtained or calculated. Moreover, to utilize the model established in this study, a siphon breaker analysis and design program was developed. The simulation program operates on the theoretical model basis and returns the result as a graph. The user can confirm the possibility of the siphon breaking by checking the shape of the graph. Furthermore, saving the entire simulation result is possible and it can be used as a resource for analyzing the real siphon breaking system.
In conclusion, the user can confirm the status of the siphon breaking and design the siphon breaker system using the program developed in this study.

The siphon breaking phenomenon was investigated experimentally and a theoretical model was proposed. A simulation program based on the theoretical model was developed and the results of the simulation program were compared with experimental results. It was concluded that the results of the simulation program matched the experimental results well.

Under the design conditions of a research reactor, the siphon phenomenon induced by pipe rupture can cause continuous outward flow of water. To prevent ...

Radio Frequency Magnetron Sputtering of GdBa2Cu3O7&#8722;&#948;/ La0.67Sr0.33MnO3 Quasi-bilayer Films on SrTiO3 (STO) Single-crystal Substrates

Here, we demonstrate a method of coating ferromagnetic La0.67Sr0.33MnO3 (LSMO) nanoparticles on (001) SrTiO3 (STO) single-crystal substrates by radio frequency (RF) magnetron sputtering. LSMO nanoparticles were deposited with diameters from 10 to 20 nm and heights between 20 and 50 nm. At the same time, (Gd) Ba2Cu3O7&#8722;&#948; ((Gd) BCO) films were fabricated on both undecorated and LSMO nanoparticle decorated STO substrates using RF magnetron sputtering. This report also describes the properties of GdBa2Cu3O7&#8722;&#948;/ La0.67Sr0.33MnO3 quasi-bilayer films structures (e.g., crystalline phase, morphology, chemical composition); magnetization, magneto-transport, and superconducting transport properties were also evaluated.

Radio Frequency Magnetron Sputtering of GdBa2Cu3O7ÃƒÆ’Ã‚Â¢Ãƒâ€¹Ã¢â‚¬Â 'ÃƒÆ’Ã…Â½ Â´/ La0.67Sr0.33MnO3 Quasi-bilayer Films on SrTiO3 STO Single-crystal Substrates

Here, we present a protocol to grow LSMO nanoparticles and (Gd) BCO films on (001) SrTiO3 (STO) single-crystal substrates by radio frequency (RF)-sputtering.

Here, we demonstrate a method of coating ferromagnetic La0.67Sr0.33MnO3 (LSMO) nanoparticles on (001) SrTiO3 (STO) single-crystal substrates by radio ...