Shield Plate Research Articles

Tympanoplasty with and without mastoidectomy for the treatment of active efficacy analysis of chronic suppurative otitis media of simple type

Objective:To analyze the surgical efficacy and safety of tympanoplasty with and without mastoidectomy for the treatment of active simple chronic suppurative otitis media（CSOM）, and to investigate whether mastoidectomy can be avoided in tympanoplasty for active CSOM. Methods:The clinical data of 55 patients（55 ears） with active CSOM were retrospectively analyzed. Based on the development of the mastoid process and the upper tympanic chamber, patients who met the criteria for wall-up mastoidectomy were classified as group A （30 patients）, and underwent tympanoplasty combined with wall-up mastoidectomy. Patients who did not meet the criteria for wall-up mastoidectomy were classified as group B（25 cases）, and underwent tympanoplasty with the opening of the middle and upper tympanic chambers and sinus drainage after partial removal of the shield plate bone. The survival rate of tympanic membrane grafts, hearing before and after surgery, and complications such as reperforation were compared between the two groups at 3 months postoperatively. Results:The overall postoperative tympanic membrane survival rate of patients with active CSOM was 96.4%（53/55）, including 96.7% in group A; 96.0% in group B. There was no significant difference in the tympanic membrane survival rate between the two groups（P>0.05）. The postoperative mean air-bone gap（ABG） was significantly reduced in both groups compared with the preoperative period, but there was no significant difference in ABG gain between the two groups（P>0.05）. No patients experienced serious adverse conditions such as peripheral facial paralysis, cerebrospinal fluid leakage, or sensorineural deafness after surgery. Conclusion:Microscopic tympanoplasty with patency of the middle and upper tympanic chambers and tympanic sinus drainage can be used to treat active simple chronic otitis media with satisfactory tympanic membrane viability and hearing improvement efficacy. This approach reduces patient trauma, prevents complications such as skin depressions in the mastoid area due to abrasion of the mastoid bone, and shortens the waiting time before surgery.

Optimisation of hybrid composite shields for hypervelocity Micro-Meteoroid and Orbital Debris (MMOD) impact

Advancements in space exploration over the last few decades have led to a sharp increase in Micro-Meteoroid and Orbital Debris (MMOD), with the associated increased risk of hypervelocity impact on satellites and space structures. The Whipple shield can mitigate the effects of such impacts and current research is exploring further developments towards effective lightweight passive shielding technology to counter the damaging effects of MMOD. With the increase in MMOD and the prospect of increased space travel in the coming years and decades, it is vital that more research is conducted and improvements are made in the development and design of efficient, lightweight shielding technology to protect both unmanned and manned spacecraft against hypervelocity impacts (HVI). The optimisation of shield design for HVI is a high dimensionality problem, suited to advanced computational approaches. Key variables in HVI shield design that should inform the focus on optimisation include: impact velocity, rear wall thickness, projectile diameter and bumper thickness. A hybrid shield configuration and numerical model are proposed and validated, with alternating layers of aluminium (AL2024) and carbon fibre composites (CFRP, T300 woven-fabric) to form a 5 mm thick target plate consisting of 5 plies. The adaptive coupled FEM-SPH method is used to model the target plates. The proposed hypervelocity shield design optimisation methodology is based on Direct Simulation-based Genetic Algorithm (DSGA) optimisation and is implemented to optimise a multi-variable shield design space. Objective weightings are used to analyse and discuss results, referring to the ratio of the kinetic energy to the shield areal density objectives. A clear transition in the impact behaviour of the optimised MMOD shields is observed in the transition region from high-velocity to hypervelocity impact, where significant levels of kinetic energy dissipation are observed below the transition region, and lower energy dissipation at hypervelocity. The shield design optimisation results show that with a weighted kinetic energy to mass objective of 90:10, the kinetic energy of the back shield plate decreases significantly (62.7%) and the areal density can be reduced by more than 18%. Alternative configurations displayed sub-optimal results based on a trade-off between objective functions.

A steel joint for driven precast concrete geothermal energy pile foundations

This invention describes a steel joint used for connecting two precast concrete driven energy pile (DEP) segments which is known as DEP joint. Precast concrete DEPs are cast in segments with a maximum length of 12 m at a concrete factory. DEPs are typically driven into the ground until bedrock; hence, in places where the bedrock is deeper than 12 m, two or more segments must be connected using a joint to produce longer energy piles. DEPs have not been frequently used because no suitable joint existed that could maintain structural integrity and provide leak-proof coupling between the pipes at the joint interface. The present invention addresses this problem by designing a steel joint that can meet the structural and hydraulic requirements of a suitable steel joint for DEPs. Each quadratic concrete energy pile segment is prefabricated in a concrete factory, where the heat transfer pipes are embedded inside the steel cage of each segment. The steel DEP joint is installed at one or both ends of each concrete segment, and has two or four sidewall channels, depending upon its size. Heat transfer pipes are coupled between every two segments, inside the sidewall channels, while the energy piles are installed at a construction site. The sidewall channels are protected using steel shielding plates that are riveted to the joint so that the pipes and the coupling inside the sidewall channels are protected against harsh frictions during the installation of the DEPs in the ground. The steel joint facilitates the installation of longer precast concrete energy piles up to the bedrock depth, especially in sites where the bedrock is deeper than a single segment length. The main advantages of precast concrete energy piles compared to cast-in-place piles are that they enable better quality control and quality assurance, as well as being easier, faster, and cheaper to install. The invented DEP joint has passed structural integrity tests as required according to the BS EN 12794 standard, and also passed hydraulic pressure tests according to the ASTM F2164 – 21; hence, it is certified to be used in construction projects. We are now looking for potential licensees to start manufacturing the joints and using them in the energy pile industry.

Safety assessment of wireless chargers for electric vehicles considering thermal characteristics.

This study employs the transient finite element method and electromagnetic heat transfer theory to assess the heating generated by high-power wireless chargers during electric vehicle charging. The analysis includes simulating and analyzing the temperature distribution of two different types of shielding plates of the wireless charger and the specific absorption rate (SAR) and head temperature rise of both adults and children in close proximity to the charger. Simulation results show that the maximum temperature rise of the copper shielding plate is 16°C lower than that of the aluminum shielding plate after charging for 1h. This temperature increase does not affect the chassis' s equipment. Regarding human safety, the induced electric field strength and SAR values in the child's head tissue are higher than those in the adult, meeting the International Commission on Non-Ionizing Radiation Protection (ICNIRP) limits. When the initial temperature is set to 37°C, the temperature rise in the heads of both adults and children is approximately equal after 1h of charging, reaching a maximum temperature rise of 0.21 and 0.23°C, respectively. These values remain below the thermal limit of ICNIRP (2°C for Type 2 tissues). The findings indicate that the copper shielding plate can provide both electromagnetic shielding and heat dissipation functions, and the electromagnetic exposure absorbed by the human body and head temperature rise within safe ranges.

Analysis of leakage flux, losses, and temperature in large synchronous generator end zone under the multi‐layer screen thickness based on novel iterative method

AbstractThe multi‐layer screen is the key component in the large synchronous generator end zone. The leakage flux, losses, and temperature of end components are significantly affected by the thickness of multi‐layer screen in the synchronous generator. To investigate the influence of multi‐layer screen thickness on the end leakage flux, losses, and temperature in the synchronous generator end zone, 1407MVA nuclear power synchronous generator is studied. Three‐dimensional transient electromagnetic field model of synchronous generator end zone is established. Three‐dimensional transient electromagnetic field in the end zone of 1407MVA synchronous generator with the multi‐layer screen is calculated based on the novel iterative method. The flux density of end components is compared and studied in the end zone under the variation of multi‐layer screen thickness. Influence of the different thicknesses of multi‐layer screen on the losses of the shield plate, screen, finger plate, and stator end core is researched. The losses of end components obtained from 3D end electromagnetic field calculation are applied to the end zone as the heat source in the three‐dimensional fluid and thermal coupled field. The temperature distribution of the end components is determined. The accuracy of the calculated results is validated by the experimental values.

FIB-shield: a structure to safely transfer and precisely mount beam-sensitive TEM specimens under focused ion beam

Focused ion beam (FIB) has been adopted extensively for transmission electron microscope (TEM) sample preparation during the past decades. However, ion beam- and deposition-induced damage during transferring and mounting of the sample cannot be effectively avoided, limiting the application of FIB in ion-beam illumination-sensitive samples. A transferring device called the FIB shield is designed and fabricated to greatly reduce the damage and contamination of the sample during transfer and mounting under Ga+ beam imaging, milling and Pt deposition. Nearly damage-free transfer and precise positioning and attachment of beam-sensitive in situ TEM nanoindentation samples are achieved. The effectiveness of the shielding plate to block Ga+ radiation damage during Ga+ beam imaging and milling and that of the buffer region to alleviate sputtering damage during Pt deposition are verified by corresponding experiments.

Vibrating capacitive electrostatic potential sensor based on a double cantilever tuning fork.

In this work, a vibrating capacitive sensor utilizing dual cantilever tuning fork resonance for electrostatic potential modulation was designed and fabricated. Initially, an electrostatic induction model was established, and the principle of non-contact electrostatic potential measurement was analyzed to identify the key factors influencing the sensor's performance. Subsequently, the vibration mode of the tuning fork was simulated to determine the mechanical dimensions of the tuning fork and the driving frequency of the piezoelectric crystal. Additionally, the concept of enhancing the uniformity of the electric field near the sensor by employing a shield plate was proposed. Simultaneously, the optimal mechanical parameters of the shielding plate were determined through multi-physical field simulation to improve the sensor's linearity. Finally, a compact calibration device was designed to measure the key performance parameters of the non-contact electrostatic potential sensor. The results demonstrate that the sensor has a measurement range of -10 to 10kV, a measurement accuracy better than ±3%, and a linearity of 0.46%. This work offers an alternative solution for non-contact potential measurement.

Innovative Design and Numerical Simulation Research of Downhole Electrical Heaters for In-Situ Oil Shale Exploitation

Summary To improve the overall performance of continuous spiral baffle heating systems, we propose in this paper two different structural models of electric heaters for in-situ shale oil wells. The models are simulated using Fluent software to investigate the flow and heat-transfer characteristics under different mass flow rates. The variation in heat-transfer coefficient, pressure drop, and overall performance of the heating plate under different gas mass flow rates and heights of heating and shielding plates are analyzed. The performance of the two different heater structures is compared with Wang’s laboratory experiment. The results show that Model I of the heating system has the best overall performance when the gas mass flow rate is between 9.74×10−3 kg/s and 1.624×10−2 kg/s, and the height of the heating and shielding plates is 35 mm at a mass flow rate of 9.74×10–3 kg/s. Wang’s pressure drop (ΔP) is more than 2.48 times higher than that of Model I and more than 6.49 times higher than that of Model II, while the heat-transfer coefficient (h) of both Model I and Model II is increased by more than 15% compared to Wang’s experiment. The overall performance (g) of Model II is increased by more than 5.7 times compared to Wang’s experiment, and the overall performance (g) of Model II is increased by more than 1.68 times compared to Model I. These results provide a theoretical basis for optimizing the design of continuous spiral baffle heating systems.

Magnetic Shielding Design of Onboard Superconducting Magnet for Electrodynamic Suspension Train

The superconducting electrodynamic suspension (EDS) train has been expected to be a promising candidate for the future ultrahigh-speed transportation due to its excellent levitation and guidance stabilities, high lift-to-drag ratio, and being free-of of active control. As a core component of the EDS train, the onboard superconducting magnet (SCM) is usually required to generate a strong magnetic field, however, which may threaten the safety of passengers. Therefore, it is indispensable to design a magnetic shielding for onboard SCM, aiming at minimizing the magnetic field in the coach of the vehicle. In this paper, a three-dimensional (3-D) finite element method (FEM) model for solving the electromagnetic problems of magnetic shielding system is established and validated by experimental results. Prior to global optimization, the effects of thickness, multi-layer and partition structure of shielding plate on the magnetic shielding are discussed primarily. It was found that the thickness has a great impact on the shielding effect, while the influence of multi-layer structure is weak. Moreover, the weight of the magnetic shielding plate can be effectively reduced by partitioning it into several blocks with different thicknesses. Based on the above studies, magnetic shielding plate is finally optimized in consideration of the thickness, multi-layer structure and partition. Consequently, the weight of the magnetic shielding plate can be reduced by 20% compared with the original one.

Transverse Thermal Behavior of a Hot‐Rolled Strip During the Edge‐Induction‐Heating Process

To obtain the transverse temperature distribution of running strips under C‐type edge induction heaters during the hot‐rolling process, a coupled electromagnetic–thermal finite‐element model is established using COMSOL, in which the electromagnetic and temperature distributions regularity with various process parameters are systematically obtained. It is shown in the results that the temperature increase is directly proportional to the frequency and current and inversely proportional to the thickness. Meanwhile, the edge temperature drop can be rapidly compensated for using an edge heater, but it also leads to the appearance of a “cat‐ear” high‐temperature zone at the edge; thus, the transverse temperature uniformity cannot be guaranteed. To improve the temperature uniformity of the running strip, a magnetic shield plate is designed to weaken the effect of the cat ear, and the effects of the size and installation position of the shielding plate on the temperature distribution are analyzed. The standard deviation and uniformity of the temperature are used to determine the uniformity of the transverse temperature, and the optimal parameter combination mode of the magnetic shielding amounts is obtained, which can provide a reference for optimizing the heating process at the edge of the strip under moving conditions.

Study of Electromagnetic Shielding for Reduction of Magnetic Fields Generate by Underground Power Cables via a Finite Element Techinique

Nowadays, with the development of the industries, the electrical types of equipment are used and applied widely for many different purposes. One of them is the use of power cables to transmit electricity over long distances, from generator stations to consumers. Local and global fields are usually created by the extensive presence of the types of currents following in power cables in general and underground cables in particular. Not only causes directly some unwanted effects on the body’s natural equilibrium, but electromagnetic fields can create the disturbance and cause interference with electronic devices. In this paper, a shielding plate is introduced to mitigate the local fields generated by a three phase current of underground power cables. The computation of magnetic fields is implemented with the magnetic vector potential formulations via a finite element technique. The developed method is applied to a practical problem.

The effect of aerosol suction distance during brushing brackets of orthodontic patients on the presence of Streptococcus and Staphylococcus

Dentists are one of the professions most at risk of infection transmission because dental care potentially produces many infectious aerosols for bacterial transmission. Using personal protective equipment and aerosol suction that meets the standards for dentists is vital to prevent cross-infection in patients in practice. This study aims to determine the effect of aerosol suction distance on the orthodontic patient bracket brushing process on total plate number and the presence of Streptococcus and Staphylococcus on the dentist’s face shield. The method used is the swab method on the face shield used by dentists after brushing orthodontic patient brackets with variations in the distance of aerosol suction to the oral cavity of 10 cm, 15 cm, and 20 cm. After 2 x 24 hours of incubation, the total plate count was calculated, and Streptococcus and Staphylococcus were identified by analyzing the characteristics of the growing colonies and executing the catalase test. The results showed that the lowest total plate number found on a face shield with aerosol suction distance of 10 cm from the oral cavity, 1.23 ± 0.01 CFU/cm2. The one-way ANOVA test obtained a significance value of p < 0.05, concluding that the variation of the aerosol suction distance affects the total face shield plate number. The presence of bacteria on the face shield was negative for Streptococcus and positive for Staphylococcus.

Use of low thermal diffusivity shielding plate to improve thermal behavior in submerged arc welding by controlling the heat input

Use of low thermal diffusivity shielding plate to improve thermal behavior in submerged arc welding by controlling the heat input

Design and calibration of the DC electric-field strength measuring instrument by horizontal vibration

The synthesis electric field is an important indicator to assess electromagnetic environment of DC transmission line, and field mill is often used in practical engineering. In order to solve the problem that the shielding plate in the field mill have unreliable grounding due to rotation and the electric field is distorted by accumulated charge, the structure of static shielding plate and moving induction plate are designed in this paper. On this basis, a complete synthetic electric field measuring device is developed. The instrument is calibrated under laboratory conditions, and the results show that calibration curve has good linear characteristic.

Planar Common-Mode EMI Filter Design and Optimization for High-Altitude 100-kW SiC Inverter/Rectifier System

Silicon-carbide (SiC) devices are receiving popularity for high-power converter systems in aircraft due to many advantages over silicon counterparts. However, the electromagnetic interference (EMI) problems are more serious with the SiC devices operating at higher switching speeds and higher switching frequencies. The common-mode (CM) EMI filter design of the high-power SiC converter is especially challenging for high-altitude applications due to the harsher requirements of insulation and heat dissipation. The optimization of the parameters and physical design of a CM EMI filter in a 100-kW SiC inverter/rectifier system operating at 50 000 ft is conducted in this article to obtain the highest power density. The effect of the switching frequency on the EMI filter volume and the total power density of the converter system is analyzed. The lower breakdown voltage of air and the higher thermal resistance of natural convection make the conventional design of the CM choke infeasible at high altitudes. A printed circuit board (PCB)-based planar CM choke is designed with the consideration of partial discharge (PD) and heat dissipation at the altitude of 50 000 ft. The structure of the CM choke is optimized with embedded electric-field shielding plates, which controls the electric-field intensity in the air below 300 V/mm. The PCB windings improve the efficiency of heat dissipation at high altitudes and reduce the profile of the CM choke. A Pareto optimization is conducted to minimize the size of the choke and the volume of the final design is only 155 cm3. The experimental results show that the CM noise is reduced effectively with the CM EMI filter. PD is not observed even at the altitude of 50 000 ft and the thermal performance is excellent with a current of 190 A. With the optimization and the dedicated design of the CM EMI filter, the power density of the converter system is up to 33.3 kW/L.

Optimized signal processing for microphone arrays containing continuously-scanning sensors

The paper presents guidelines for the optimal treatment of signals from microphone arrays that include continuously-scanning sensors. The signals from the scanning sensors are non-stationary due to the time-varying source-sensor distance and the traversing of an acoustic field with spatially-varying statistics. Quasi-stationarity has been sought in past studies by dividing the signals into blocks and applying a frequency-dependent window within each block. Optimal schedules versus frequency for block size and block overlap are proposed that enhance the spatial resolution while containing the computational cost. The guidelines are applied to the acoustic fields emitted by an impinging-jets source and a subsonic turbulent jet in isolation and integrated with a shielding plate. The noise source distributions are obtained through a direct spectral estimation approach in which the error between the modeled and measured far-field statistics is minimized. The ability of the continuous-scan paradigm, coupled with the proposed treatment of the signal, to provide high-definition noise source maps is demonstrated.

Ultrahigh-efficiency solar energy harvesting via a non-concentrating evacuated aerogel flat-plate solar collector

Non-concentrating solar collector is extensively used in residential and industrial sectors for low-temperature (<120 °C) applications. The current non-concentrating solar collectors are underperformed in the intermediate temperature range (120–300 °C), which immensely limits their application. In this paper, a structure-optimized evacuated flat plate solar collector with a transparent aerogel layer and back shield plate is proposed to solve the above issue. The experimental test is conducted to validate the numerical model of the evacuated flat plate solar collector and the spectral properties of the transparent aerogel layer. The analysis results manifest that the structure optimized evacuated aerogel flat-plate solar collector possesses ultrahigh thermal efficiency in the low and intermediate temperature range with a relatively thin aerogel layer (5 mm) adopted and it is superior to state-of-the-art work. The thermal efficiency of the evacuated aerogel flat-plate solar collector is 60.47% at an inlet temperature of 155 °C, which is a 20.68% enhancement over that of the prototype collector. This research is fundamental to the future development of non-concentrating solar collectors and instrumental in the decarbonization goal for residential buildings and industrial heating energy supplements.

Analysis of Induced Field in the Brain Tissue by Transcranial Magnetic Stimulation Using Halo-V Assembly Coil.

As a noninvasive neuromodulation technique, transcranial magnetic stimulation (TMS) has already exhibited a great impact in clinical application and scientific research. This study presents a finite element method-based simulation of the Halo-V assembly (HVA) coil placed on the five-shell spherical human head model to examine the distributions of induced electric and magnetic fields. The performance of the designed HVA coil is evaluated by comparing the simulation results with the commercially available Halo-FO8 (HFA) assembly coil and standard single coils including the Halo and V coils. The simulation results indicate that the HVA coil shows an improved focality in terms of electric field distribution than the other single and assembly stimulation coils. Additionally, the effects of a magnetic shield plate and magnetic core on the designed HVA coil are investigated. Results indicate that the magnetic shield plate and magnetic core are proficient in further improving the stimulation focality. Therefore, the HVA TMS coil results in a safe and effective stimulation with enhanced focality of the target region as compared to the existing assembly coil.

Design and manufacture of thermoplastic carbon fiber/polyethylene terephthalate composites underbody shield to protect the lithium-ion batteries for electric mobility from ground impact

Recently, the electric mobility has emerged with great prospects as there has been a growing interest in and demand for eco-friendly energy. The electric vehicle uses a large number of lithium batteries as sources of power, and the lithium battery poses a risk of fire and explosion when the external impact is loaded. Therefore, in this study, an underbody shield (UBS) was designed and manufactured using carbon fiber reinforced thermoplastic composites for battery protection. The underbody shield is composed of two parts, which are the main shield plate and collision protection bar (CPB). Mechanical behavior against impact was analyzed through finite element analysis considering the position of the CPB and the shape of the underbody shield plate. For the UBS, the hybrid composites (Carbon fiber (CF)/polyethylene terephthalate (PET) and self-reinforced polypropylene (SRPP) composites) were used and the ratio between the CF/PET and SRPP was optimized. Through a finite element analysis, the optimal underbody shield was designed with a thickness of 2.4 mm and a hybrid ratio of CF/PET:SRPP as 1:2. Finally, the designed underbody shield was manufactured using a thermo-forming process and mounted to an electric vehicle, and then a vehicle crash test was performed with a concrete obstacle. The developed underbody shield could protect the battery against the impact damage successfully, showing that the deformation of a rear part was within 5 mm and no battery leakage occurred.

Numerical simulation of the process of Zr58Nb3Cu12Ni12Al15 bulk glasses fragment penetrating into two separated plates and forming debris cloud

Impact of the Zr58Nb3Cu12Ni12Al15 bulk metallic glasses (BMG) fragment on shield plate generates a debris cloud and causes great damage to the hindside witness target. However, conventional FEM and experimental methods are difficult to track the complex formation process and damage behavior of debris cloud. In this study, such process of a 10 mm spherical metallic glasses fragment penetrating into two LY12 separated plates is investigated, both experimentally and computationally. By introducing JH-2 constitutive model, the mechanical properties of Zr-base BMG with high strength and low plasticity are reproduced; Meanwhile, by introducing the FEM/SPH coupling method, the failed element is converted into SPH, thereby simulating the impacting and fragmentation process of the fragment, as well as the characteristics of the transiently generated debris cloud. The simulation results are in good agreement with the experimental observations. During the penetrating process, a large number of stress concentration areas are found inside the fragment, thus promoting the forming process of the debris; the mass and velocity loss rates of the residual fragment at different stages are clarified quantitatively. Further, the debris cloud in space can be divided into three zones according to the morphology, i.e. the reverse motion zone, the debris-dispersion zone and the debris-concentration zone, and the debris-concentration zone is the main factor causing damage efficiency of the witness target.