Line Structure Research Articles

Novel 6‐GHz/80.8% fractional bandwidth filtering power divider with ultra‐large coupling coefficient using air‐dielectric broadside‐coupled lines

AbstractIn the letter, a wideband filtering power divider (FPD) with ultra‐large coupling coefficient using air‐dielectric broadside‐coupled lines is proposed. The broadside‐coupled line and single transmission line are alternately connected to construct three resonators, which can be used for large bandwidth and high selectivity filtering. An improved substrate‐integrated suspended line (SISL) structure with two inner layers is developed. In the structure, the broadside coupling occurs by the air. The overall structure is implemented based on the low‐cost FR4 dielectric material. The designed FPD is simulated and fabricated. The results demonstrate its excellent performance, with center frequency of 6 GHz, a fractional bandwidth (FBW) of 80.8%, a maximum coupling coefficient of 0.84, an insertion loss of less than 0.29 dB, and an out‐of‐band rejection of more than 52 dB.

Analysis and design of a wide stop‐band and high out‐of‐band suppression BPF

AbstractThis paper proposes a wide bandpass filter (BPF) with high out‐of‐band suppression and wide stop‐band characteristics. An interdigital coupled line structure loaded by a rectangular resonator ring is employed to generate three transmission poles in the pass‐band and an additional transmission zero (TZ) in the stop‐band, thereby achieving a wider pass‐band while enhancing stop‐band suppression. Compared to traditional coupled‐line structures, the structure mentioned in this paper offers significant advantages in designing filters with wide stop‐bands and high out‐of‐band suppression. Furthermore, open‐circuit T‐stub, and a pair of open‐circuit stub are used to generate multiple parasitic TZs at high frequencies, which is adopted to further expand the stop‐band range. Measurement results shows that the insertion loss of the BPF is of −2.86 dB within the range of 7.05–12.20 GHz. The stop‐band ranges from 13 to 48 GHz with an out‐of‐band suppression of −27 dB, especially when the out‐of‐band suppression is −40 dB, the stop‐band frequency range is 16.40–31.35 GHz.

Influence of Interior Column on the Behaviour of Quasi-Rectangular Tunnel

The growing population in major cities around the world requires significant development of transportation infrastructure, especially underground system. It requires the construction of more subway lines, and larger tunnel cross-sections. In underground construction, a cross-sectional shape which is a combination of circular and rectangular tunnels is an advanced trend. This shape incorporates the advantages of both forms. There are two terminologies used to classify these shapes, including sub-rectangular and quasi-rectangular tunnels. While the sub-rectangular tunnel lacks an interior column, the quasi-rectangular tunnel includes an interior column located at the center of tunnel. Recent studies focus on separately investigating the behavior of sub-rectangular and quasi-rectangular tunnels using various methods such as numerical methods, analytical methods, and experimental methods. The present study conducted a numerical comparison of these two types of tunnels. The results indicated that the presence of an interior column help to increase the stability of the lining structure. The internal forces within the quasi-rectangular tunnel with an interior column are smaller than those of the sub-rectangular tunnel and quasi-rectangular tunnel without an interior column.

Experimental investigation on the load-bearing capacity and deformation behaviour of the composite lining with polyurethane compressible layer

Lining structures for tunnels in rheological rocks are susceptible to large deformations and damage. Installation of a polyurethane (PU) compressible layer between the primary and secondary lining provides a potential solution to mitigate large deformation hazards. Although the capability of PU-enhanced composite lining in adapting and absorbing large deformation has been found, its underlying load-bearing mechanism and deformation behaviour remain less understood. To fill the gap, large-scale model tests were conducted using a self-designed loading test setup, primarily focusing on the mechanical response of PU-enhanced composite lining. Ten lining specimens with varying thicknesses (25, 37.5, and 50 mm) and densities (50, 100, and 150 kg/m3) of the PU compressible layer were investigated. The digital image correlation (DIC) analysis technique was used to detect real-time deformation and strain fields under loading conditions. Results demonstrated that the PU compressible layer enhanced the ultimate load, toughness, and deformation capacity of the composite lining by an average of 17.6 %, 164.6 %, and 157.4 %, respectively. The load-displacement response of the specimens with PU compressible layer could be categorized into four stages: pre-cracking, post-cracking, strain-hardening, and failure. The primary lining experienced the largest vertical displacements among the specimens with the PU compressible layer, followed by the compressible layer and the secondary lining. Although the specimens exhibited similar progressive failure modes, there were variations in crack distribution and propagation. The analysis of rock-support interaction indicated that increasing the thickness of the PU compressible layer mainly affects the deformation capacity when the secondary lining reaches its elastic limit.

Attenuation of an ultrashort pulse in a folded meander microstrip line with two passive conductors

SummaryIn this article, we investigated a new structure of a protective meander line (ML): a meander microstrip line (MSL) with two passive conductors. The existing theory of ultra‐short pulse (USP) attenuation in MLs is presented for the first time. Based on this theory, we determined the number of decomposed pulses at the output of the MSL line with two passive conductors, and, for the first time, formulated the conditions for pulse decomposition in the line. The folding of the MSL line into non‐core turns was studied in detail. As a result of this article, we proposed a new theory that involves the utilization of additional groups of decomposed pulses for enhanced USP attenuation. These additional groups were thoroughly examined, and the delays of pulses from these groups were defined. This analysis allowed identifying the reason for their appearance. It was revealed that folding the ML into non‐core turns allows further attenuation of the USP amplitude, which increases with the increase of the number of non‐core turns. To validate the obtained simulation results, we performed experimental measurements and obtained good consistency of the results. The N‐norms analysis demonstrated that the combined use of such folding and passive conductors reduces the probability of electrical breakdown, arc discharge, and dielectric breakdown. The maximum USP attenuation at the output was 24.9 dB. As a result of useful signal integrity analysis, it is proposed to use a folded MSL together with a USB 2.0 “Full‐speed” interface with a data transfer rate of 12 Mbit/s. In addition, it is proposed to use such MSLs in DC power circuits.

Transmission line tower inclination measurement method based on three-dimensional laser scanning and inter frame difference

Abstract The purpose of this study is to propose a method based on three-dimensional laser scanning and frame difference technology to measure the inclination of transmission line towers, so as to realize accurate monitoring of transmission line structure. Firstly, the multi-scale Retinex algorithm is used to enhance and preprocess the transmission line tower image to improve the image quality. Secondly, the method of frame difference and background difference is combined to detect and identify the inclined tower. Finally, the point cloud data of inclined tower is obtained by using three-dimensional laser scanning technology, and the inclination of transmission line tower is calculated by coordinates. The experimental results show that this method has high accuracy and reliability, with an error of less than 0.15 × 10−5 and an inclination of less than 0.17°. It is proved that this method can improve the monitoring efficiency of transmission lines, has good effects in engineering practice, and can provide effective means for the safe operation of transmission line structures.

Coupled thermodynamic and thermomechanical modelling for compressed air energy storage in underground mine tunnels

Compressed air energy storage (CAES) in underground mine tunnels using the technique of lined rock cavern (LRC) provides a promising solution to large-scale energy storage. A coupled thermodynamic and thermomechanical modelling for CAES in mine tunnels was implemented. Thermodynamic analysis of air during CAES operation was carried out. Difference in temperature and pressure evolution when considering real air thermophysical properties and varying heat transfer properties, as opposed to a simplified thermodynamic model, was revealed. Elastic plane strain (EPS) analysis was implemented to evaluate the influences of initial stress of the lining structure, quality grades of surrounding rock, thermal effect and the cyclic nature of loadings on mechanical behaviour. 3D elastoplastic damage (3DEPD) analysis considering steel reinforced concrete (SRC) lining was implemented to evaluate the damaged mechanical behaviour. Divergences between EPS analysis and 3DEPD analysis were unveiled. It is suggested that, when it comes to tunnel stability, simplifying the thermodynamic model is of least concern, instead, the initial stress of the lining structure is of critical importance and 3DEPD analysis considering SRC lining shall replace EPS analysis. The insights of this study will provide important guidance for the designing and feasibility study of LRC in mine tunnels for application of CAES.

A perturbed energy level of the holmium atom

This study focuses on two lines of atomic holmium for which standard hyperfine structure analysis could not be performed. The lines were studied by laser-induced fluorescence spectroscopy using a Ti-sapphire laser. Usually, the hyperfine structure of spectral lines is described by the well-known Casimir formula. However, this was not possible in the analysis of these two lines. The common feature of these two lines is that their upper energy levels are identical. In this study, hyperfine structure analyses were performed by considering a perturbation in the hyperfine splitting of the upper energy level of both lines. Shifts were introduced for the hyperfine sub-levels with F = 4 to 7 of the perturbed level, with the help of which the positions of all components of both laser lines could be satisfactorily explained. The same behaviour was found for three other spectral lines present in the Fourier transform spectrum, which are connected to the same perturbed upper energy level. The perturbation must be caused by a hitherto unknown energy level of odd parity with small J -value. The energy, J - quantum number and hyperfine constant A of this level were estimated.

On the Impact of a Change in Slag Batch on the Freeze Lining Structure and Stability

On the Impact of a Change in Slag Batch on the Freeze Lining Structure and Stability

Epoxiconazole altered hepatic metabolism in adult zebrafish based on transcriptomic analysis

Epoxiconazole (EPX) is a triazole fungicide, which has been widely used in pest control of cereal crops. However, its extensive use has led to concerning levels of residue in water bodies, posing substantial risks to aquatic life. In this study, we characterized the toxicological effects of EPX on 6-month-old male and female zebrafish at 70 and 700 μg/L, respectively. The results revealed that EPX exposure markedly increased both body length and weight in zebrafish of both sexes, consequently elevating their condition factor. Besides, EPX exposure resulted in notable alterations in hepatic histopathology. These changes included loosened hepatocyte structure, ballooning degeneration, nucleolysis, and disappearance of cell line, with male zebrafish exhibiting more severe damage. High concentration of EPX also significantly increased hepatic lipid accumulation in male zebrafish, as well as increased hepatic triglyceride (TG) levels. Correspondingly, there was a notable alteration in the transcription of genes including cyp51, hmgcr, and PPAR-γ, which associated with cholesterol and lipid metabolism. Interestingly, with the hepatic transcriptomic analysis, high concentration of EPX produced 195 upregulated and 107 downregulated differential expression genes. Both KEGG and GO analyses identified significant enrichment of these genes in lipid and amino acid metabolism pathways. Notably, some key genes involved in the steroid synthesis pathway were marked upregulated. In addition, molecular docking study confirmed that EPX could bind CYP51 protein well (△G = −7.7 kcal/mol). Taken together, these findings demonstrated the multiple toxic effects of EPX on adult zebrafish.

Mechanical Behavior of Secondary Lining in Super Large-Span Tunnels Considering Temperature Effects

Temperature stress has a significant impact on the structural stress of (super) large-span tunnel lining, which can easily lead to structural fatigue damage and premature cracking. With the increasing scale and quantity of super large-span tunnels, the issue of temperature stress in secondary lining has attracted widespread attention. Previous studies have paid little attention to the influence of temperature stress on the structural internal forces of ordinary small–medium-span tunnels, but this influence cannot be ignored for super large-span tunnels. We take the Letuan Tunnel (a double-hole eight-lane tunnel) of the Binzhou-Laiwu expressway renovation and expansion project in Shandong Province as a case study and analyze the mechanical response of the secondary lining through on-site measurement. Moreover, a numerical simulation was conducted to evaluate the effects of self-weight and temperature stress on the secondary lining of the case tunnel. The results indicate that: the stress of the secondary lining concrete and steel bars is greatly affected by seasonal temperature changes. The compressive stress of the concrete and steel bars is significantly greater in summer than in winter, and the tensile stress is greater in winter than in summer. Furthermore, multiple measurement points have shown a phenomenon of transition between tensile and compressive stress states. The stress of concrete and steel bars fluctuates periodically with a sine function over time, with a fluctuation period of one year. The structural stress increases with the increase of summer temperature and decreases with the decrease of winter temperature. The fluctuation amplitude of stress in the inner side of the lining concrete and steel bars is greater than that on the outer side. Among them, the stress amplitudes of the inner and outer sides of the concrete are between 0.77–1.75 MPa and 0.44–1.07 MPa, respectively, and the stress amplitudes of the inner and outer steel bars are between 5–31 MPa and 7–13 MPa, respectively. The safety factors in summer are lower than those in winter. The minimum safety factors for secondary lining in summer and winter are 3.4 and 4.6, respectively, which can meet the safety requirements for service. The average axial forces of the secondary lining under the coupling effects of self-weight and temperature in winter and summer are 528 MPa and 563 MPa, respectively, which are significantly greater than the combined axial forces under their individual effects. The bending moment distribution of the secondary lining at the tunnel vault, inverted arch, wall spring and other positions under the coupling effect of self-weight and temperature is different from or even opposite to the bending moment superposition result under the two individual actions. The achieved results reveal that the influence of temperature stress on the service performance of the lining structure cannot be ignored, and the research results can provide useful reference for similar tunnels and related studies.

Numerical Analysis of Ground Surcharge Effects on Deformation Characteristics in Shield Tunnel Linings

To investigate the deformation characteristics of shield tunnel linings under ground surcharge, finite element software was employed to create a detailed three-dimensional model of the staggered assembly of the shield tunnel lining. This model includes components such as precast concrete segments, reinforcements, and joints (comprising bent bolts, washers, and bolt sleeves). Additionally, the model accounts for interface frictions between segments and the interactions between different rings. The reliability of the numerical model was verified based on the results of a full-scale model test. Additionally, the model accounts for interface frictions between segments and the interactions between different rings. Changes in tunnel convergence, joint tensioning, bolt stresses, reinforcement stresses, and concrete crack development were systematically analyzed. The results indicate the following: (1) the deformation mode of the lining structure under ground surcharge resembles a “transverse ellipse”. Joints located near the haunch opened along the outer arc, while those near the vault and bottom opened along the inner arc. The restraining effect of the bolts on joints opening in the inner arc was greater than that on the outer arc. Notably, when the opening of the inner arc reached 4.9 mm, the bolt stress escalated to the yield strength of 640 Mpa. (2) Under larger loads, the lining structure’s joints are susceptible to greater deformation, resulting in the tensile yielding of local reinforcement within these joints. (3) Cracks predominantly occur near the haunch, vault, and bottom of the lining structure, with the central angle of crack distribution ranging between 70° and 85°.

Characterization of Embedded and Thinned RF Chips

This work studies the effect of thinning down chips with transmission line structures for flexible embedding technology. Test chips with 90 Ω grounded coplanar waveguide (GCPW) transmission lines have been designed and manufactured to characterize the high-frequency performance before and after embedding in sheet molding compound (SMC), and thinning down from 300 μm to 20 μm. Molding first technology enables single-die or multiple-die thinning with the embedding material while being held in the exact position, where the subsequent fanout copper (Cu) redistribution layer (RDL) structuring realizes the direct contacts to the embedded chip, followed by semiadditive manufacturing of traces. The embedded and thinned chips are characterized by S-parameter measurements in the frequency range from 20 MHz to 65 GHz using a vector network analyzer (VNA). The results show the feasibility of the examined embedding and thinning processes which are suitable for millimeter wave (mmWave) components as shown by the example of a G-CPW transmission line without degrading its RF performance in terms of characteristic impedance and attenuation.

Influence of secondary lining thickness on mechanical behaviours of double-layer lining in large-diameter shield tunnels

In large-diameter shield tunnels, applying the double-layer lining structure can improve the load-bearing properties and maintain the stability of segmental lining. The secondary lining thickness is a key parameter in the design of a double lining structure, which is worth being explored. Based on an actual large-diameter shield tunnel, loading model tests are carried out to investigate the effect of the secondary lining thickness on the mechanical behaviours of the double lining structure. The test results show that within the range of secondary lining thicknesses discussed, the load-bearing limit of the double-layer lining increases with growing secondary lining thickness. As a passive support, the secondary lining acts as an auxiliary load-bearing structure by contacting the segment. And changes in secondary lining thickness have a significant effect on the contact state between the segment and secondary lining, with both the contact pressure level and the contact area between the two varying. For double-layer lining structures in large-diameter shield tunnels, it is proposed that the stiffness of the secondary lining needs to be matched to the stiffness of the segment, as this allows them to have a coordinated deformation and a good joint load-bearing effect.

Research on the deformation and settlement characteristics of tunnel lining structures based on distributed fibre optic sensing technology

To study the deformation and settlement characteristics of tunnel lining structures, a tunnel lining structure model was designed based on distributed fibre optic sensing technology. Compared to the cylindrical model used in traditional tunnel lining structural model experiments, in this study, a reinforced concrete structural model was adopted, which can embed fibre optics in the structure, which is closer to actual tunnel engineering conditions. Central and symmetrical concentrated loading experiments were carried out with a simply supported reaction frame. The results of the distributed fibre optic monitoring were compared and analysed with those of traditional monitoring methods to verify the reliability of the distributed fibre optic monitoring results. The numerical simulations of the experiments were conducted by using finite element analysis. By comparing and analysing the simulation and experimental results, the correctness of the simulation calculation results were verified. On this basis, the impact of concrete strength, circumferential reinforcement spacing, and longitudinal reinforcement strength on the deformation and settlement of the tunnel lining structure were analysed. The results show that the hierarchical effect of the strain monitoring results obtained by the embedded fibre optic is more obvious, indicating that the radial monitoring effect of the embedded fibre optic on the tunnel structure is less affected by other external factors than the strain gauge, and the monitoring data are more accurate and effective, with good engineering characteristics. Improving the concrete strength, appropriate circumferential reinforcement spacing, and increasing the longitudinal reinforcement strength can effectively enhance the ability of the structure to resist deformation at the stress location. These factors play a significant role in improving the overall resistance to deformation and safety of the structure. The research results provide a theoretical basis and experimental data for the application of distributed fibre optics in monitoring the deformation and settlement of tunnel lining structures.

Application of a machine learning method to model-based library approach for critical dimension measurements using CD-SEM

A model-based library (MBL) method has already been established for the accurate measurement of the critical dimension (CD) of semiconductor linewidth using critical dimension scanning electron microscope (CD-SEM) images. In this work, the MBL method is further investigated by combining CD-SEM image simulation and a neural network algorithm. The secondary electron linescan profiles were first calculated using a Monte Carlo simulation method, enabling us to obtain the dependence of linescan profiles on the selected values of various geometrical parameters (e.g. top CD, sidewall angle and height) for Si and Au trapezoidal line structures. Machine learning methods have then been applied to predict the linescan profiles from a randomly selected training set of the calculated profiles. The predicted results agree very well with the calculated profiles with the standard deviations of 0.1% and 6% for the relative error distributions of Si and Au line structures, respectively. The findings show that the machine learning methods can be practically applied to the MBL method for reducing the library size, accelerating the construction of the MBL database and enriching the content of the available MBL database.

Derivation of Creep Parameters for Surrounding Rock through Creep Tests and Deformation Monitoring Data: Assessing Tunnel Lining Safety

Tunnel instability and lining integrity are intimately tied to the creep properties of the surrounding rock. The acquisition of rock mass creep parameters is critical in ascertaining the appropriate timing for lining construction. Nevertheless, creep tests on rock specimens conducted in a controlled setting cannot be straightforwardly extrapolated to rock mass creep analysis. This study performs laboratory-based creep tests on mudstone samples and establishes the corresponding creep constitutive model. The integration of a Mohr–Coulomb element with the Burgers model in series serves to characterize the yield creep behavior of the rock mass. Additionally, the research outlines a series of 100 orthogonal experiments utilizing randomized creep parameters and formulates a GA-BP neural network inversion model. Employing long-term deformation measurements from the crown and sidewalls of the project site, this study deduces the creep parameters of the mudstone in the investigated tunnel section and examines the prolonged deformation traits of the surrounding rock. Drawing on the deformation traits of the surrounding rock and the forces impacting the primary support and lining structures, this paper evaluates the earliest and latest viable lining casting periods and pinpoints an optimal timing interval for lining implementation. The methodologies employed herein can serve as a benchmark for analogous endeavors internationally.

Design, Synthesis, and in-silico Studies of New Disubstituted Benzimidazoles: Evaluation of In-vitro Anticancer and Antimicrobial Activity

A series of thirteen new benzimidazole scaffolds 4(a-m) was synthesized by nucleophilic substitution of 2-chloro- N-(aryl)-acetamides 3(a-m) with 2-(substituted phenyl)-1H-benzo[d]imidazoles 2(a-e) in N.N-Dimethylformamide. All the synthesized compounds were tested on the MCF-7 cell line, followed by antibacterial and antifungal activity. The anticancer activity was determined using MTT assay technique, whereas the antimicrobial activity was carried out using two-fold serial dilution technique. Among all the tested compounds, compound 4b exhibited the highest anticancer and antimicrobial activity, comparable to the standard drug. Finally, the binding mode analysis of the highly active compounds was performed at the active binding sites of the co-crystallized structure of the MCF-7 cell line (PDB ID 1ZXM) and glucosamine-6-phosphate synthase (PDB ID 2VF5). In silico absorption, distribution, metabolism, and excretion studies were also carried out.. KEYWORDS :Benzimidazoles, Cytotoxicity, in silico studies, MCF-7 cell lines, MTT assay.

Population structure, favourable alleles and grain quality traits of promising advanced breeding lines of lowland rice adaptable to acidic soils

Population structure, favourable alleles and grain quality traits of promising advanced breeding lines of lowland rice adaptable to acidic soils

New energy transmission line fault location method based on Pearson correlation coefficient

The access of new energy power source makes the traditional transmission line structure become complex, and due to the influence of power electronic device control strategy, the fault characteristics have been fundamentally changed, resulting in the traditional transmission line fault localization method can not be applied to the new energy sending line. To address the above problems, this paper analyzes the transient current characteristics of different power supply faults, and learns that there are obvious differences in the transient currents on both sides of the fault point inside and outside the transmission line area, and then proposes a new energy transmission line fault localization method based on the Pearson correlation coefficient, which determines the fault location by calculating the correlation coefficients of the fault waveforms of the neighboring monitoring points. Finally, comparative experiments are carried out under different fault types and fault locations to further verify the applicability of the proposed method.