Equal Spacing Research Articles

In Situ Transformation of Hybrid Bismuth Halide into Rhombohedral Bismuth for Electrochemical CO2 Reduction to Formate

AbstractBi‐based electrocatalysts have attracted high attention due to their high selectivity for formate, low cost, and high biocompatibility. Surface modification with halides can adjust the surface charge distribution of metal catalysts, thereby regulating the binding force of the intermediate. Organic‐inorganic hybrid bismuth halides provide an alternative, especially low dimensional structures. Herein, zero‐dimensional hybrid bismuth halides containing Bi4I16 units (denoted as Bi4I16) was recommended as pre‐catalyst due to the Bi ⋅ ⋅ ⋅ Bi spacing in Bi4I16 is 4.760 Å, nearly equaling to the Bi ⋅ ⋅ ⋅ Bi spacing in rhombohedral Bi (4.750 Å). The equal spacing may be more beneficial for the electricity‐driven in situ conversion and rearrangement of Bi atoms in the catalytic process. As a contrast, zero‐dimensional bismuth halide containing Bi2I9 units (denoted as Bi2I9) with shorter Bi ⋅ ⋅ ⋅ Bi spacing (4.2415 Å) was prepared. The working electrode prepared by Bi4I16 ink was measured for CO2RR, and the partial formate current density can reach 8.2 mA cm−2 at −1.1 V vs RHE. The Bi4I16 catalyst delivers a maximum Faradaic Efficiency (FE, ~80 %) for formate at −0.86 V vs RHE and maintain a FE higher than 78.5 % after 16 h.

Analysis of train-induced aerodynamic characteristics and pressure-relief measures relating to fully enclosed noise barriers installed on railway bridges

Fully enclosed noise barriers (FENBs) are increasingly being installed on high-speed railway bridges for noise pollution control. However, the aerodynamic effects of high-speed trains passing FENBs have an adverse impact on barrier durability and generate micro-pressure waves. In this paper, a numerical model of a train passing an FENB on a bridge is established. The aerodynamic pressure distribution along the FENB is analyzed for both a single train and two trains passing one another. The propagation characteristics and evolution mechanisms of pressure waves are then investigated. The results show that the pressure is lower at the ends of the FENB and higher in the middle along the direction of train travel. The peak positive and negative pressures at the mid-span are 1.95 and 4.47 times higher than those at the ends, respectively. This distribution is caused by the propagation, superposition, reflection, and attenuation of pressure waves. Compression waves account for 78.9% of the peak positive pressure. An amplification factor must be considered when estimating the impact of two trains passing one another. Analysis of five pressure-relief schemes shows that arranging a single pressure-relief hole at a high-pressure location effectively alleviates the over-pressure in the FENB. The overall pressure-relief effect is an exponential function of the single opening area. Considering a constant opening area, arranging several relief holes at equal spacing optimizes the adverse pressure distribution compared with the single-hole relief scheme. The equivalent forces of the multi-hole scheme are 3.35% and 7.58% lower than in the single-hole scheme.

Investigation of Cu Corrosion Defects Induced by Humidity Imbalance in the Cu Damascene Process of Semiconductors

As integrated circuit design rules shrink in semiconductor, Copper (Cu) has been employed as the back end of line (BEOL) interconnect metal to enhance device performance through reduced resistivity and resistive-capacitive delay.[1] However, Cu metal lines are prone to degradation caused by Cu oxidation-induced defects, including extrusions and voids, owing to their inherent properties.[2] Consequently, it becomes essential to regulate the oxidation rate during the chip fabrication process, particularly when the Cu metal line is exposed during the Damascene process. This control is crucial for ensuring long-term reliability and achieving a higher yield.[3]From the learning of earlier technological nodes, we are aware to and already precisely controlling both process queue time and wafer surface humidity. We must exercise control over the queue time, addressing both inter-process intervals and in-process queuing. [4] This underscores the importance of managing queue time and maintaining low environmental humidity to mitigate wafer surface defects when the FOUP (Front Opening Unified Pod) is opened at the EFEM (Equipment Front End Module).[5] Those humidity and queue times related Cu corrosion defects have been mitigated by N2 purge in FOUP and reducing the wafer quantity. However, dividing the lot, typically consisting of 25 wafers, by half or less to reduce queue times leads to an imbalance in low humidity due to N2 purging. This occurs when the FOUP is opened in EFEM.This paper examines Cu corrosion under low humidity conditions in a FOUP with a small quantity of wafers, specifically examining the influence of queue time during N2 purging in the EFEM. Through simulation of the interaction between the inlet air entering the EFEM and the purged N2 gas, a vulnerable area is identified where copper oxidation takes place. In addition, we propose an arrangement to mitigate high humidity, supported by experiments conducted under real equipment conditions.Fig. 1 shows Cu corrosion defects after ILD etching at around 20% RH in the FOUP. This defect is only observed in the lower slot of the FOUP on the N2 purged load port. Figure 2 illustrates a chart depicting the humidity inside the FOUP under various conditions. The humid region within the FOUP when opened on the N2 purged load port without wafers. (Fig.2a) While the extent of the humid area is contingent upon the flow rate of the N2 purge and the intake of air through the Fan Filter Unit (FFU), the vortex of the inlet air from the cleanroom (<42% RH) is notably observed at the bottom and front side of the FOUP. Therefore, wafers stored in the lower slot of the FOUP face an increased risk of Cu corrosions when subjected to elevated humidity levels during processes like ILD etching and subsequent cleaning. Specifically, an extended queue time amplifies the probability of Cu defects occurring in this high-humidity slot compared to slots with lower humidity. We observed an unintended increase to 28.2% RH in specific configurations when reducing the quantity of wafers to minimize queue time. (Fig. 2b)Hence, we propose an arrangement for wafers that maintains low humidity with small quantity. When placing 12 wafers in the FOUP, an arrangement with equal spacing from the first slot to the 25th slot ensures uniform N2 flow, thereby reducing the highest humidity from 28.2% RH to 14.0% RH by half. (Fig.3a) Alternatively, positioning all wafers on the upper section is another method. (Fig.3b) Therefore, by halving the quantity of wafers and reducing the process wait time by half, and applying the optimal wafer arrangement that maintains low humidity balance even with a small number of wafers, we confirmed the absence of Cu corrosion.

Unequally-spaced slot strategy for radiation null reduction in single SIW-embedded antenna element

The incorporation of higher-order modes (HOMs) can substantially augment the antenna gain and bandwidth, but this improvement is typically accompanied by compromised radiation performance including radiation nulls and higher side lobe levels. In this study, an inventive strategy is introduced to reduce the radiation nulls and the side lobe levels of a single antenna element by positioning multiple slots of the radiating element at unequal spacing. Dual hybrid HOMs are analyzed inside a substrate integrated waveguide-based cavity to design a wide band, enhanced gain dual-polarized antenna. The radiating element of the antenna is designed with multiple slots positioned at unequal spacing but symmetrical along the origin. This methodology provides three-fold advantages: a reduction of side lobes, an adjustment of phase center, and a significant reduction of radiation nulls. The antenna has been fabricated, and experimentally validated. The antenna exhibits a reduction in radiation null to − 0.5 dB, a phase adjustment of the main lobe to 0°, and a reduction in side lobe level from − 14.4 dB (N = 2, equal spacing) and − 15.5 dB (N = 4, equal spacing) a maximum of − 19.7 dB (N = 4, unequal spacing) at 12.35 GHz in the phi-0 plane. Excellent agreement between measured and simulated results corroborates the efficacy of the proposed approach. The significant improvement in the radiation performance of the single-element antenna design sets the antenna design apart from the state-of-the-art solutions.

Optimization of fin arrangement in solar thermal storage devices and convolutional neural network modeling

Solar energy, a renewable and eco-friendly source, faces challenges in aligning energy production with storage durations. Phase change materials (PCMs) effectively tackle this issue, yet their poor thermal conductivity limits solar thermal storage device performance. Conventional solutions involve adding fins, but limited volume compromises overall heat storage capacity. Our study enhances device performance by rearranging fins while maintaining the same area. The H/R = 0.5 fin arrangement with equal spacing significantly improves heat storage, reducing total melting time by 54.31% with a higher entropy value. Further, arranging five fins, predominantly in the lower part, shortens PCM melting time without compromising upper material melting, enhancing device temperature uniformity. Utilizing computed data, we trained a Convolutional Neural Network (CNN) model, maintaining a maximum error within 5%, with an actual maximum error of only 1.56%. The efficacy of CNN in addressing prediction challenges is noteworthy, showcasing improved solar thermal storage device performance.

Three-dimensional measurement based on equal spacing binary fringe coding

Abstract Binary fringe projection technology can effectively avoid the measurement error caused by nonlinearity in structured light three-dimensional measurement system. In this paper, a binary fringe projection coding based on equal spacing is proposed firstly, the image sequence projected by binary fringes with equal spacing is corresponding to the sinusoidal intensity values in the same period one by one, and then the sinusoidal fringes are generated by weighted superposition. The experimental results show that, compared with the traditional four-step and 12-step phase shifting methods, the mean square error of the synthesized sinusoidal pattern is reduced by 36.74% and 18.24% respectively, and the mean square error of the distance between the obtained spherical point cloud of the standard sphere and the center of the fitting standard sphere is reduced by 89.36% and 77.27% respectively.

First radial excitations of mesons and diquarks in a contact interaction

We present a calculation for the masses of the first radially excited states of 40 mesons and diquarks made up of u, d, s, c, and b quarks, including states that contain one or both heavy quarks. To this end, we employ a combined analysis of the Bethe-Salpeter and Schwinger-Dyson equations within a self-consistent and symmetry-preserving vector-vector contact interaction. The same set of parameters describes ground and excited states of mesons and their diquark partners. The wave function of the first radial excitation contains a zero whose location is correlated with an additional parameter dF which is a function of dressed quark masses. Our results satisfy the equal spacing rules given by the Gell-Mann Okubo mass relations. Wherever possible, we make comparisons of our findings with known experimental observations as well as theoretical predictions of several other models and approaches including lattice quantum chromodynamics, finding a very good agreement. We report predictions for a multitude of radial excitations not yet observed in experiments. Published by the American Physical Society 2024

Narrowing row spacing and adding inter-block promote the grain filling and flag leaf photosynthetic rate of wheat under enlarged drip tube spacing system.

Enlarging the lateral space of drip tubes saves irrigation equipment costs (drip tubes and bypass), but it will lead to an increased risk of grain yield heterogeneity between wheat rows. Adjusting wheat row spacing is an effective cultivation measure to regulate a row's yield heterogeneity. During a 2-year field experiment, we investigated the variations in yield traits and photosynthetic physiology by utilizing two different water- and fertilizer-demanding spring wheat cultivars (NS22 and NS44) under four kinds of drip irrigation patterns with different drip tube lateral spacing and wheat row spacing [① TR4, drip tube spacing (DTS) was 60cm, wheat row horizontal spacing (WRHS) was 15cm; ② TR6, DTS was 90cm, WRHS was 15cm; ③ TR6L, DTS was 90cm, WRHS was 10cm, inter-block spacing (IBS) was 35cm; and ④ TR6S, DTS was 80cm, WRHS was 10cm, IBS was 25cm]. The results showed that under 15-cm equal row spacing condition, after the number of wheat rows served by a single tube increased from four (TR4, control) to six (TR6), NS22 and NS44 exhibited a marked decline in yield. The decline of NS22 (9.93%) was higher than that of NS44 (9.04%), and both cultivars also showed a greater decrease in grain weight and average grain-filling rate (AGFR) of inferior grains (NS22: 23.19%, 13.97%; NS44: 7.78%, 5.86%) than the superior grains (NS22: 10.60%, 8.33%; NS44: 4.89%, 4.62%). After the TR6 was processed to narrow WRHS (from 15 to 10cm) and add IBS (TR6L: 35cm; TR6S: 25cm), the grain weight per panicle (GWP) and AGFR of superior and inferior grains in the third wheat row (RW3) of NS22 and NS44 under TR6L increased significantly by 26.05%, 8.22%, 14.05%, 10.50%, 5.09%, and 5.01%, respectively, and under TR6S, they significantly increased by 20.78%, 9.91%, 16.19%, 9.28%, 5.01%, and 4.14%, respectively. The increase in GWP and AGFR was related to the increase in flag leaf area, net photosynthetic rate, chlorophyll content, relative water content, actual photochemical efficiency of PSII, and photochemical quenching coefficient. Among TR4, TR6, TR6L, and TR6S, for both NS22 and NS44, the yield of TR6S was significantly higher than that of TR6 and TR6L. Furthermore, TR6S showed the highest economic benefit.

Identifying stationary microbial interaction networks based on irregularly spaced longitudinal 16S rRNA gene sequencing data

IntroductionThe microbial interactions within the human microbiome are complex, and few methods are available to identify these interactions within a longitudinal microbial abundance framework. Existing methods typically impose restrictive constraints, such as requiring long sequences and equal spacing, on the data format which in many cases are violated.MethodsTo identify microbial interaction networks (MINs) with general longitudinal data settings, we propose a stationary Gaussian graphical model (SGGM) based on 16S rRNA gene sequencing data. In the SGGM, data can be arbitrarily spaced, and there are no restrictions on the length of data sequences from a single subject. Based on the SGGM, EM -type algorithms are devised to compute the L1-penalized maximum likelihood estimate of MINs. The algorithms employ the classical graphical LASSO algorithm as the building block and can be implemented efficiently. ResultsExtensive simulation studies show that the proposed algorithms can significantly outperform the conventional algorithms if the correlations among the longitudinal data are reasonably high. When the assumptions in the SGGM areviolated, e.g., zero inflation or data from heterogeneous microbial communities, the proposed algorithms still demonstrate robustness and perform better than the other existing algorithms. The algorithms are applied to a 16S rRNA gene sequencing data set from patients with cystic fibrosis. The results demonstrate strong evidence of an association between the MINs and the phylogenetic tree, indicating that the genetically related taxa tend to have more/stronger interactions. These results strengthen the existing findings in literature. DiscussionThe proposed algorithms can potentially be used to explore the network structure in genome, metabolome etc. as well.

Limit Cycle Oscillating Detonation Wave Behavior Analysis Within a Rotating Detonation Engine

Limit cycle oscillation (LCO) detonation wave behaviors are presented and analyzed for test times exceeding 20 s in a water-cooled rotating detonation engine (RDE). LCO detonation waves exhibit cyclic acceleration and deceleration, resulting in oscillating wave spacing at unique process conditions. In previous RDE studies, similar behaviors have been studied as microsecond-scale instabilities leading to ascending or descending modal transitions. In the current work, however, LCO waves are considered a persistent wave mode, occupying unique portions of the operational envelope adjacent to those of their equally spaced counterparts. These occurrences of LCO waves are repeatable, enduring behaviors. A method to generate shifted contour surfaces specifically intended to extract and analyze wave spacing variation through time, termed limit cycle oscillation visualization (LCOV) surfaces, is presented. LCOV surfaces transform data into the reference frame of a primary traveling wave and are used to analyze quasi-steady, short-timescale, and transitional LCO modes. Results are leveraged to understand the relationship between fill height, wave strength, local wave acceleration, and subsequent LCO wave spacing for individual wave sets. Quasi-steady LCO waves display wave spacing oscillations between equal spacing values associated with ±1 wave across runs exceeding 18 s.

Inspection Times and Optimal Censoring Scheme for Generalized InvertedExponential Distribution with Progressive type I Interval Censored Data

In this article, two issues related to the design of the experiment are investigated; namely the inspection times and optimal censoring. In the first issue, we study four different approaches to determine the inspection times, namely; pre-specified, equally spaced, optimally spaced, and equal probability using two optimality criteria. In the second issue, we identify the optimal censoring scheme by finding the expected numbers of removals or proportions that attain a specific optimality criterion using two optimality criteria considered. Numerical comparisons using the Monte Carlo simulations are provided of the inspection times, optimum control schemes issues for different parameters and different sample sizes. Statistical measures such as bias and root mean square error for both pre-specified and equal space methods are calculated and the inspection times for different values of the censoring percentage h are obtained.

Yields, growth and water use under chemical topping in relations to row configuration and plant density in drip-irrigated cotton

BackgroundWater deficit is an important problem in agricultural production in arid regions. With the advent of wholly mechanized technology for cotton planting in Xinjiang, it is important to determine which planting mode could achieve high yield, fiber quality and water use efficiency (WUE). This study aimed to explore if chemical topping affected cotton yield, quality and water use in relation to row configuration and plant densities.ResultsExperiments were carried out in Xinjiang China, in 2020 and 2021 with two topping method, manual topping and chemical topping, two plant densities, low and high, and two row configurations, i.e., 76 cm equal rows and 10+66 cm narrow-wide rows, which were commonly applied in matching harvest machine. Chemical topping increased seed cotton yield, but did not affect cotton fiber quality comparing to traditional manual topping. Under equal row spacing, the WUE in higher density was 62.4% higher than in the lower one. However, under narrow-wide row spacing, the WUE in lower density was 53.3% higher than in higher one (farmers’ practice). For machine-harvest cotton in Xinjiang, the optimal row configuration and plant density for chemical topping was narrow-wide rows with 15 plants m-2 or equal rows with 18 plants m-2.ConclusionThe plant density recommended in narrow-wide rows was less than farmers’ practice and the density in equal rows was moderate with local practice. Our results provide new knowledge on optimizing agronomic managements of machine-harvested cotton for both high yield and water efficient.

Unsteady, two-dimensional magnetohydrodynamic (MHD) analysis of Casson fluid flow in a porous cavity with heated cylindrical obstacles

This research presents an analysis of entropy generation during natural convection in a porous medium using triangular heated cylindrical obstacles with equal spacing. The study consists of three cylindrical obstacles arranged in a triangular pattern. Each cylinder is uniformly spaced from its neighboring cylinders, creating equilateral triangles throughout the arrangement. All of these cylindrical obstacles are heated. The triangular arrangement guarantees an even distribution of obstacles across the experimental space. The governing equations, with entropy, are numerically solved using the finite element method. The study aims to investigate the interactions between several key elements in fluid dynamics: Casson fluid, magnetohydrodynamics, the Darcy–Forchheimer model, entropy, and natural convection. The goal is to gain insights into the individual behaviors of these elements and their interactions in combined systems. The results indicate that the Casson fluid parameter has an impact on the flow and heat transfer characteristics, while the Hartmann and Nusselt numbers exhibit control mechanisms for the intensity of natural convection and affect the patterns of isotherms, streamlines, and entropy.

Study of thermodynamic properties of N particles in one-dimensional harmonic oscillator potential

We have calculated the partition function and hence the energy and the specific heat of a two-particle system in n numbers of finite nondegenerate energy levels of equal spacing distributed according to classical and quantum statistics. We have then extended our study for N identical particles placed in 1D harmonic oscillator potential. It is observed that the specific heat of bosons and fermions are exactly the same in this potential at any temperature, and at high temperature the results are similar to that for the classical particles. The partition function of a system of two particles placed in 2D harmonic oscillator potential has also been determined as comparison.

3D numerical simulation of frequency-domain elastic wave equation with a compact second-order scheme

Finite-difference frequency-domain (FDFD) modeling has gained popularity in recent years. However, its main drawback lies in the need to solve large sparse linear systems, which is computationally expensive, especially for 3D elastic wave simulations. The existing elastic wave optimal schemes improve the simulation accuracy at the cost of using large-sized stencils or high-order finite-difference (FD) operators, and most of them only consider equal grid spacing and solid media. To address these issues, we have proposed a compact second-order scheme for simulating 3D elastic wave propagation. Starting from the second-order FD discretization of the first-order velocity-stress expression, the compact discrete scheme of the second-order elastic wave equation is obtained by using a parsimonious staggered-grid strategy to eliminate the stress variables. In this way, the scheme preserves the ability to handle high-contrast velocity and liquid-solid media, and has a more compact and sparse impedance matrix than existing schemes, which helps save computational costs. We also use an antilumped mass strategy to further improve the modeling accuracy. Dispersion analysis indicates that our compact second-order scheme has better accuracy than the classic second-order scheme, and even better accuracy than the average derivative 27-point scheme at large Poisson's ratio. Compared with the existing 3D elastic wave schemes, the compact second-order scheme has advantages in computational cost for the same grid. Finally, we employ these schemes to implement 3D numerical simulations, validating the effectiveness of our proposed scheme.

Novel method for total organic carbon content prediction based on non-equigap multivariable grey model

Predicting total organic carbon content plays a crucial role in shale gas reservoir evaluation. To address multi-variable, imperfect logging data and non-equigap characteristics, this study developed a multi-variable grey derivative model for predicting the total organic carbon content trend. To begin with, the non-equigap factor is introduced and the parameter identification of the new model is established on the basis of least square method. Then, to reduce fluctuations in the original data, the weighted geometric average weakening operator is introduced. In addition, considering the system stability, the derivation method is used to calculate the time response formula of the model. Furthermore, two validation cases are provided to verify the validity of this novel model. Finally, the model is applied to the Fuling shale gas field in China for practical forecasting. Compared to other models, such as the grey model, statistical model, and artificial intelligence model, the proposed model achieved higher prediction accuracy in the three cases. Specifically, this model obtained 95.62%, 95.88% and 94.55% prediction accuracy for total organic carbon content. Results that the new model effectively addresses the limitations of previous studies that focus on single-parameter or equal spacing issues.

Experimental study on the effect of partial shear studs layout on flexural behavior of steel-concrete composite beams

In steel-concrete composite beams, partial shear connection offers advantages including greater ductility and lower cost. However, partial shear connection constraints on composite beam structural performance, such as reduced beam stiffness, increased steel-concrete interface slip, etc., should not be neglected. Several researches have revealed that shear connector layout is one of the main approaches to limit partially composite beam vulnerability. Shear connector layout optimization has not been completely investigated experimentally, and its effect on composite beam structural performance is still unknown. This paper focusses on the experimental study of the effect of shear connectors layout on the flexural performance of composite beams. It reports the optimization of the layout of shear connectors based on blocked distribution of shear connectors laid in a single row, while concentrating the highest number of shear studs towards the supports of a simply supported composite beam. A fully composite beam with normal layout of shear studs was tested as control specimen, while the rest of the beams used partial shear connection (η = 0.5). Beams with partial shear connection had 3 different layouts of shear studs. The first had uniformly distributed shear studs, and the rest had shear studs laid out in 2 and 3 blocks each of uniform spacing respectively. The results showed that the beam with 3 blocks layout each of equal spacing of shear studs had the closest best structural performance to the fully composite beam and had better ductility than the latter.

A modified equally-spaced method (MEQS) for fibre placement in additive manufacturing of topology-optimised continuous carbon fibre-reinforced polymer composite structures

This study proposes a modified equally-spaced (MEQS) method for the path design of continuous fibres in additive manufacturing (AM) of topologically optimised composite structures. The MEQS method addresses the low fibre infill rate issue of the traditional Equally-Spaced (EQS) method by utilising the Offset method to generate looped printing paths around the internal cavities and gaps between continuous fibre paths. The developed MEQS method was first illustrated against EQS and Offset methods using an open-hole composite plate in which topology and material orientation were simultaneously optimised using the discrete–continuous parameterisation (DCP) method. Actual printing path-based finite element modelling showed that the MEQS method achieves a 25.32% increase in stiffness compared to the Offset method. Experimental testing of the additively manufactured open-hole composite plates showed that the MEQS method improves the stiffness and strength by 15.52% and 27.38%, respectively, compared to the Offset method. The proposed MEQS was further demonstrated through two other case studies by finite element modelling, showing that the stiffness of MEQS has increased by an average of 66.71% and 14.95% compared to EQS and Offset, respectively.

What should I use to calculate vehicle EES?

Comprehensive crash analysis includes calculating impact speed, which requires the determination of kinetic energy expended on the deformation of the vehicle's structural elements at the point of contact during a collision. The accuracy of the input data affects the resulting analysis of the crash. Therefore, this article aims to analyse selected factors influencing the determination of Energy Equivalent Speed (EES) determination using the CRASH3 algorithm: the extent of damage using defined measurement points, deformation width, and also limit speed b0. The variables were varied depending on selected factors such as the extent of damage, the type of collision (overlap), and also vehicle type (vehicle category classification). The presented study concluded that using 2 equally spaced measurement points to define the deformation profile should not be recommended in forensic practice when using CRASH3 algorithm. Using 7 measurement points seems more appropriate in case of equal spacing, even though the differences in calculated EES are not high when using 5 or 6 measurement points, especially with respect to the inaccuracy/technically acceptable tolerance of the EES value determination. The resulting EES is significantly influenced by variation of the deformation width. The used b0 range had a significant effect on the resulting EES value only in the case of SUVs. These vehicles show higher stiffness, which supposes the use of lower b0 values should not be recommended.

An evaluation of cutting head design of current tunnel Boring machines and suggestions to improve machine Performance

ABSTRACT This paper evaluates cutterhead design of current tunnel boring machines (TBMs) in considerations with the actual cutting action of discs observed on the most common cutter heads. The discs on the current TBM cutter heads were found to predominantly perform asymmetrical cutting action, which generates excessive sideway forces impairing steering action of the machine. The effective s/p ratios related to actual cutting action of discs emerge to be significantly higher than those of the laboratory-determined values, and this consequently leads to adverse cyclic deepening effect. The gross lateral loads arising from excessive side forces were stated to be minimised if the adjacent discs are arranged to cut in symmetrical position by adopting appropriate cutterhead design methods suggested in this paper. Furthermore, a dynamic analysis was carried out in terms of reaction forces on cutter heads of different geometries, and it was indicated that flat face cutter heads have better steering abilities than conical or domed types, in mixed face conditions. Similar analysis on disc angular spacing also inferred that scattered type disc arrangements with equal angular spacing are preferable to cutterheads with spoke or star type lacing, in terms of cutterhead balance.