Ground Shield Research Articles

Intraocular Pressure Monitoring Smart Contact Lens with High Environmental Stability

AbstractSmart contact lenses (SCLs), integrating various functional components, serve as a platform for wirelessly intraocular pressure (IOP) monitoring. Accurate and dynamic measurements offer crucial clinical references for patients with ocular hypertension. Nevertheless, the complex ocular environment poses great challenges, particularly for inductor–capacitor–resistor (LCR) type IOP sensors, which suffer signal instability due to variations of ocular dielectric properties. Here, an innovative IOP monitoring sensor with robust environmental stability, achieved by integrating the ground shield, is proposed. Employing a capacitive pressure sensor with porous polydimethylsiloxane (PDMS) structure encased in a hydrogel, the study successfully demonstrates high‐sensitivity monitoring of IOP changes using in vitro porcine eyes. This optimized design empowers the wireless IOP sensor with a sensitivity of 1.15 ‰/mmHg. It exhibits exceptional frequency stability after undergoing 100 wear cycles on ten distinct porcine eyes and remains reliable across a wide range of metabolite concentrations typical of normal eyes. Notably, any observed frequency shift translates into IOP changes within a 3 mmHg range, showcasing its suitability for repeated use and daily IOP monitoring.

Stack-Layer Dual-Frequency Ultrasound Array With Ground Shielding for Super-Harmonic Imaging

Stack-Layer Dual-Frequency Ultrasound Array With Ground Shielding for Super-Harmonic Imaging

Mathematical modelling for interaction between soft ground and small curvature shield tunneling considering viscoelastic characteristics influences

The current analytical solutions for predicting the ground settlements induced by small curvature tunneling in soft ground are generally conducted on the assumption of linear elastic foundation and provide little attention on the soil rheology. This paper introduces a mathematical model to estimate the small curvature tunneling induced adjacent ground settlement considering the soil viscoelasticity. By introducing the Boltzmann viscoelastic ground model under the Laplace transform, the time domain parameters converted from Poisson's ratio and shear modulus are derived to further obtain the viscoelastic ground loss solution and the Mindlin solution. Then, the proposed viscoelastic solutions are employed for the ground settlement caused by the over-excavation and imbalanced loads for the small curvature tunnel, which accounts for the soil rheology influence. The accuracy of the mathematical model is then verified by comparisons with in-situ observed data and 3D numerical simulation results, as well as good agreement is obtained. Finally, the parametric analyses are performed to estimate the influence for transverse and longitudinal surface settlements, including tunnel curvature radius, shield cutterhead face radius, over-excavation value, creep time and shear modulus ratio of viscoelastic ground.

Modeling, analysis, and shielding of the electric field between extra-high-voltage AC transmission lines and oil pipelines

The static charges and induced voltages from extra-high-voltage alternating current transmission lines (EHVACTLs) on parallel oil pipelines (POPLs) raise the risk levels for people and animals. Thus, the objective of this paper was to reduce and/or mitigate the electric field which is concentrated on POPLs by using grounded shield wires under EHVACTLs. Three techniques are employed to reduce the electric field effects on POPLs of two distinct types of transmission lines (TLs), 500 kV and 220 kV. The first technique involves raising the tower’s height to improve the clearance space between the POPLs and the TL conductors. The second technique is increasing the horizontal distance between the POPLs and the nearest stressed conductors of the TL. The third technique involves placing shield wires beneath the stressed conductors of the EHVACTLs. The electric field under the EHVACTLs is calculated with and without the grounded shield wires using charge simulation method. The results of the first technique revealed that with increasing the tower height from 10 m to 15, 20, 25, and 30 m, the electric field decreased by 43.75%, 62.5%, 68.75%, and 75%, respectively. Herein, employing the second technique, the electric field intensity is reduced by 20% and 21% depending on the POPL placed at a distance from the right stressed conductor equal to the horizontal clearance between conductors of 500 kV and 220 kV, respectively. Besides, the results of the third technique proved that the shield wires under the EHVACTLs reduced the electric field intensity on the POPLs by 17.65% and 24.71% for 500-kV and 220-kV TLs, respectively.

Low Noise Amplifier at 60 GHz Using Low Loss On-Chip Inductors

This paper proposes the technique of using low loss on-chip inductors in the design of low noise amplifier (LNA) that offers high gain and lower noise figure. Upon the substrate of octagonal spiral inductors, a surface of patterned ground shield is inserted that significantly reduces the substrate loss. This effect limits the penetration of electric filed into the substrate, thereby improving the inductor’s Quality (Q) factor and decouples the substrate parasitic that results with smaller series resistance. These effects result with improved gain and noise figure of LNA at 60 GHz when the designed inductors are included in it to serve as gate, source, and load inductances. The proposed work uses an inductively degenerated 3-stage common-source LNA in a 65-nm CMOS process. Simulation results show that the LNA using custom designed inductors achieves the peak gain of 17.02 dB at 56 GHz with a noise figure of 5 dB at 60 GHz for the power consumption of 10 mW. The figure-of-merit (FOM) is 14.56 which is 0.8 times more than the LNA design using off-chip inductors. A complete LNA layout using custom designed inductor footprints has been presented and analyzed.

РАСЧЕТ ШНЕКОВОГО КОНВЕЙЕРА ЩИТОВЫХ МАШИН С ГРУНТОПРИГРУЗОМ

The issues of calculation of structural and kinematic parameters, as well as power indicators of work in the design of screw conveyors of the mixed ground shield tunnel boring machines

Plane-Wave Coupling Analysis of a Distribution Line With a Multipoint Grounded Shield Wire and Surge Arresters Using the Three-Dimensional FDTD Method

A high-frequency electromagnetic plane wave arises owing to a high-altitude electromagnetic pulse (HEMP), which may cause overvoltages in distribution lines and insulation failure. To protect distribution lines from such overvoltages properly, it is necessary to evaluate the effectiveness of countermeasures. Nowadays, the finite-difference time-domain (FDTD) method, which is one of the full-wave numerical approaches, has become a powerful tool for analyzing electromagnetic transient phenomena. In this article, first, we propose a simplified approach to modeling an impinging plane wave by taking into account homogeneous soil parameters in the three-dimensional FDTD method on the basis of a total field/scattered field technique for the analysis of HEMP-based plane-wave coupling. Second, using the proposed technique, we carry out the statistical analysis of overvoltages in a three-phase distribution line and evaluate the effectiveness of a multipoint grounded overhead shield wire and surge arresters, which are commonly used as lightning protection measures, while modeling the reinforcing bars of concrete utility poles, earth electrodes, and vertical grounding wires to simulate a realistic condition.

A physical‐based model for on‐chip double‐layer spiral inductors with a ground shield

AbstractA physical‐based analytical model for double‐layer inductors to reduce the on‐chip area occupied is presented. A simple DC inductance model is developed based on self‐inductance and mutual inductance of metal segments. A new method has been adopted to accurately estimate the nonuniform distribution of currents due to skin and proximity effects, and a ladder structure is used to characterize them. Dielectric and substrate electric effects are analyzed, and a ground shield is used to reduce losses. The effective inductance reduction due to the eddy current in the silicon substrate is modeled by a negative mutual inductance between the metal spiral lines and the substrate. All the model parameters can be calculated from the structure sizes and process parameters. On‐chip inductors with different parameters were fabricated for the verifications. The EM simulated results and measured results are in good agreement with the proposed model. Thus, it is suitable for different technologies. This model can facilitate the design and optimization of on‐chip inductors for RF IC applications.

Ground loss model for analyzing shield tunneling-induced surface settlement along curve sections

The shield tunneling along the curve section is widespread in cities. This paper proposes a ground loss model for shield tunneling along such sections. A prediction formula for the surface settlement was deduced using the mirror theory and the Mindlin solution, and a finite difference model was constructed based on the Changsha power tunnel engineering project. The law of surface settlement caused by shield tunneling along a curve section was analyzed. The theoretical prediction results and numerical simulation results were found to be in good agreement with the field monitoring data, proving the correctness of the proposed ground loss model and theoretical prediction formula. The over-cutting gap causes the transverse surface settlement to be asymmetrically distributed, whereas the integrative gap at the shield tail causes it to be symmetrically distributed. The transverse surface settlement curve is nonuniformly distributed in a “V” shape when shield tunneling along the curve section. The surface settlement is maximum inside the curve section, and the settlement value inside the curve section is greater than that outside, which is different from the surface settlement law in the straight section. The nonuniform distribution of the ground loss and shield shell friction was found to be the cause of the uneven surface settlement distribution.

An Innovative Sensor for Cable Joint Monitoring and Partial Discharge Localization

To enhance grid reliability, weak points must be monitored. One of the weaknesses is the cable joints, which are prone to failure and can cause great losses from both a technical and economical point of view. Joints failures are usually caused by impurities unintentionally added during installation that cause partial discharges (PDs). In time, these discharges erode the insulation and generate treeing up to a destructive discharge between the conductor and the ground shield. For this reason, a method for the early detection of defects in joint installation and their online monitoring is required. A previously developed sensor was improved by adapting it for this purpose. It is based on the measurement of the induced current on a conductor due to a charge variation. It was experimentally tested on an actual joint in which defects were artificially introduced. Results show that the sensor is able to detect partial discharges. Moreover, a method for PD localization was developed. The first results show a coherency between the possible defect location, numerical simulations and historical background.

RF Performance of Devices Processed in Low-Temperature Sequential Integration

RF performance and intertier coupling of CMOS processed in 3-D sequential integration are investigated. pMOS transistor fabricated with a 500 °C thermal budget features good RF figures of merit with ${f}_{t} =105$ GHz and ${f}_{\text {max}} =175$ GHz for a gate length of 45 nm and ${V}_{\text {DD}} = -1$ V. Moreover, we demonstrate that the low- ${k}$ SiCO oxide spacer and low polysilicon gate resistance obtained with the low temperature process contribute to ${f}_{\text {max}}$ results that are better than high temperature process (above 1000°). Finally, we illustrate the crosstalk effects and the influence of the low-tier transistor gate voltage ${V}_{\text {G}}$ on the top-tier threshold voltage ${V}_{T}$ . We also show that a polysilicon ground shield integrated under the top-tier transistor substantially attenuates the intertier RF field coupling effects.

Damages and wear of tungsten carbide-tipped rippers of tunneling machines used to cutting large diameter reinforced concrete piles

It is sometimes inevitable to cut the parts within the designed tunnel alignment of foundation reinforced concrete (RC) piles with cutting tools of soft ground shield machines when tunneling in densely populated areas. Cutters employed to cut the RC piles of the soft ground shield machines must be modified to do the work. Based on the construction of cutting 14 large diameter RC piles of Guangji Bridge in Suzhou metro construction, damages and wear of the modified rippers to cut the RC piles is thoroughly examined. A test of using the modified rippers to cut two cast-in-place RC piles was conducted to explore the feasibility of the cutting work. Based on the test, height differences between the rippers, and between the rippers and the scrapers were arranged. An analysis of damages and wear of the modified rippers was performed considering cutter installation radii and the arranged height differences. Due to the excessive and repetitive forces acted on the height-increased rippers, breakages of the carbide inserts at the two sides of the cutter top dominated and the damaged cutters suffered substantial wear. Wear amounts of the rippers increased with the increases of their installation radii, and they were in direct variations.

Determination of the Contribution of the Ground-Shield Losses to the Microwave Performance of On-Chip Coplanar Waveguides

In this article, we characterize and model two parasitic effects that become apparent in the performance of coplanar waveguide interconnects in CMOS. One is the transverse resistance introduced by a patterned ground shield in coplanar waveguide interconnects, which significantly contributes to the shunt losses. The other one is the parasitic coupling between the input and output ports through the ground shield. The latter effect is particularly accentuated in relatively short lines and complicates the determination of the propagation constant using line–line algorithms at several tens of gigahertz. We demonstrate that using the proposed methodology, excellent model–experiment correlation can be achieved in the modeling of these types of interconnects up to at least 60 GHz.

Improvement of the minimum detectable activity of a free release monitor for small articles

This paper presents results of the development of a small-sized free release monitor designed for the release of materials, various hand tools, equipment and instruments of nuclear enterprises and laboratories staff that weight up to 50 kg, from radiation control. To increase the registration sensitivity of controlled radionuclides, 12 scintillation units based on a 3"x3" sized NaI (Tl) crystal were used as gamma-radiation detectors. Volume of the measuring chamber of the monitor amounted to 200 L, the chosen thickness of the low-back ground shielding was 50 mm. The values of the minimum detect able activity of the designed monitor for the point sources 123I, 131I, 99mTc, 18F were better than 100 Bq with measurement time not exceeding 60 seconds.

Mathematical modeling of the technological process of operation and parameters of the device for formation of longitudinal rollers (pawls) between cotton rows

This article reveals the features of mathematical modeling of the technological process of work and the parameters of the device for the formation of longitudinal pawls between cotton rows. And also, the results of the STUDY are presented, and the following main conclusions were made: the task of mechanizing the formation of longitudinal legs can be solved by lifting the soil from the two side furrows and throwing it into the central furrow using a palletizing device with active working organs. Studies have shown that for the qualitative formation of longitudinal dogs between rows of cotton, it is advisable to use a device with a single-pass continuous auger. To avoid damage to cotton seedlings, to ensure the required productivity with minimal energy consumption, the screw device must have the following parameters: the screw diameter is 400 mm, the inner and outer diameters of the screw pipe 420 and 426 mm; respectively, the pitch of the screw is 320 mm; the rotation speed of not less than 325 rpm; and the mounting angle relative to horizontal-not more than 35 °; the entry angle into the ground shield located in front of the screw tube, the device needs to be within 24-25º.

The effect of the particle size distribution curve on the abrasivity of non-cohesive soils in LCPC test

Despite the widespread use of soil excavating tools, including soft ground shield TBMs, there is not any universally accepted method for soil abrasivity assessments. However, different experimental models have recently developed to study the abrasivity of soil materials. LCPC test, developed in Laboratoire Central des Ponts et Chaussées, is one of the most common, simplest, and most available approaches, which has wide use in the prognosis of wear on soil and hard rock cutting tools. In the present study, the effect of the distribution curve of soil particle size on its abrasive behavior was investigated. Synthetic abrasive samples were made with mixing crushed silica grains and fine silica particles in different ratios. LCPC tests were performed on the samples under different water contents and stress levels. The obtained LCPC abrasive coefficient values revealed the effect of the distribution curve of soil particle size on its abrasive behavior. Based on the results, fine particles alone do not result in high wear rates. However, their presence, especially in wet conditions, has a considerable effect on the recorded wear amounts. Moreover, increasing the share of fine particles in the composition of the abrasive sample decreases the effect of applied stress levels on wear rates.

The effect of a metal PGS on the Q ‐factor of spiral inductors for RF and mm‐wave applications in a 28‐nm CMOS technology

In this paper, the effect of a metal patterned ground shield (PGS) on the performance of monolithic inductors is investigated. To this aim, three spiral inductors integrated in a 28-nm fully depleted (FD) silicon-on-insulator (SOI) CMOS technology are analyzed by means of a 3-D FEM-based commercial software. The inductors have been designed at different operating frequencies in the RF and mm-wave ranges to better explore the effect of the PGS. Extensive analysis revealed that the shield is able to improve the quality factor (Q-factor) only of the inductor operated at the lowest frequency (ie, K-band). On the contrary, it has a detrimental effect on the Q-factor of the inductors working at higher frequencies. This is mainly due to induced losses in the PGS itself, which are so high to frustrate the substrate loss reduction. This result gives a different perspective to the adoption of the PGS for CMOS integrated inductors, which is largely recommended to improve inductor performance in the current state of the art.

Patterned Ground Shield for Inductance Fine-tuning

ABSTRACT Post-fabrication inductance variation is a big issue faced by chip designers of sensitive circuits, and on-chip tunable inductors seem to provide the solution to this problem. In addition, tunable inductors also benefit circuits that require the multi-frequency operation. This paper is on the design of a tunable inductor which utilizes the patterned ground shield (PGS) to enable fine-tuning capability. This work is unique as this is the first time that the PGS is used for this purpose, previous researches were more on the Q-factor merit provided by the inductors with PGS. In this work, inductor's and PGS parameters influencing the inductance tuning range and Q-factor performances were first determined. Subsequently, inductors with PGS made from different metals and track spacing were designed, with electronic circuitries implemented to control the grounding of each PGS metal finger. The hypothesis that the floating and grounding of each PGS metal finger can change the magnetic flux of the inductor which contributes to the inductance variation was verified using Sonnet EM. Measured results show that a 5.2% inductance tuning range and Q-factor of 5.9 were achieved at the Bluetooth frequency of 2.5 GHz for an inductor with 2.0 µm track spacing and a polysilicon PGS with finger spacing of 2.0 µm. The tunable inductor was further integrated into a power amplifier (PA) and simulation results show that it enables the PA to achieve the design specification at the frequency range of 3.3–3.8 GHz, dedicated for the sub-6 GHz 5G application.

IMPROVED PERFORMANCE OF LNA USING HIGH QUALITY FACTOR PGS ON-CHIP SPIRAL INDUCTORS

This paper presents a detailed study of on-chip spiral inductors with patterned ground shield (PGS) inserted between the spiral inductorand the silicon substrate. This new design has been implemented in source degeneration cascode lownoise amplifier (LNA) circuit to show how the PGS inductors improve the performance of the circuit. An operation in 1.8V supply voltage, source degeneration cascode LNA structure was studied with both technology and PGS inductors. In this paper, the Agilent ADS (Advanced Design System) simulation software and TSMC 0.18μm CMOS process parameters were adopted to achieve the low-cost characteristics and high integration to fit the performance of 2.4 GHz LNA design under IEEE 802.11a specification.According to the co-simulation results, the forward gain (S21) improved from 13.432 to 21.474 dB, and the (S12)is below the typical value of -15dB. The input impedance (S11) and the output impedance (S22) also represented good performance. In addition, the minimum noise figure was quite good. Thus, the LNA circuit with PGS inductorswas better in the availability and the possibility of 802.11a specification.

A Scalable, Broadband, and Physics-Based Model for On-Chip Rectangular Spiral Inductors

A scalable, broadband, and physics-based compact model for on-chip spiral inductors with rectangular outline shape is demonstrated for the first time in this paper. A simple dc inductance model is developed based on the current sheet approximation. The reduction in inductance due to the flow of eddy current in a back metal plate is considered using the method of images. A three-ladder network is shown to be sufficient to accurately model skin effect caused due to the magnetic field setup at high frequencies. Geometry-dependent expression suitable for rectangular cross-sectional metal strips is presented to predict the proximity effect. Physics-based expression for the substrate capacitance is derived. The proposed model is also shown to have a good correlation in the presence of a patterned ground shield. The proposed model is verified across CMOS process parameters that affect the inductor performance, such as metal thickness, substrate resistivity, and substrate thickness. Furthermore, model accuracy is also validated across design parameters such as spiral width, spacing between turns, number of turns, and diameter. The model is shown to have a good agreement with both EM simulations and measurements.