Alignment Design Research Articles

Optimizing mountain railway alignments considering geo-hazard impacts based on a knowledge graph

Abstract Alignment design is pivotal in determining the macroscopic hazard to a railway, especially in complex mountainous regions with dense geologic hazards. In this work, to apply the experience of handling geo-hazards that accumulated in manual alignment design, the related alignment design principles are summarized via an event tree. Based on this, a method is proposed to construct a knowledge graph (called GeRAD-KG) for mountain railway alignment design considering geo-hazard impacts of debris flows, landslides and rockfalls, with which to structurally represent corresponding design principles. Then, a construction cost—geologic hazard bi-objective optimization model incorporating the knowledge-driven hazard assessment is constructed. To solve the model, a GeRAD-KG-guided distance transform algorithm integrating a multicriteria tournament decision is tailored. Finally, a real-world case indicates that the alternative generated by the proposed method can reduce the construction cost and geological hazard compared to the single-objective optimization alternative, which verifies the effectiveness of proposed method for assisting actual railway design in a mountainous region with dense geo-hazards.

Knowledge graph-driven mountain railway alignment optimization integrating karst hazard assessment

Karst hazard is a considerable threat that should be considered in railway alignment design for mountainous regions with dense water systems. Nevertheless, alignment design principles in karst regions have not been systematically studied. Moreover, a quantitative karst hazard assessment model is currently lacking for automated alignment optimization. To solve the above problems, based on the analyses of karst inducing factors and hazard representation, the railway alignment design principles in karst regions are summarized through an event tree. A highly-coupled knowledge graph (called KaRAD-KG) modeling method is proposed. Then, a bi-objective alignment optimization model considering railway construction cost and karst hazard (mainly including hazard components of synclinal karst, anticlinal karst and karst depression) is constructed. To solve the optimization model, a knowledge-driven distance transform algorithm incorporating a karst hazard assessment method and a multicriteria tournament decision method is customized. Finally, the application in a real-world case indicates that the proposed method can generate an alignment which reduces construction cost by 3.39 % and karst hazard by 18.73 % compared to the best manually-designed alternative, which verifies the effectiveness of this method for assisting actual railway alignment design in a karst-dense mountainous region.

Pushing boundaries in slurry microtunneling: Innovations in microtunnel boring machine design for hard rock conditions

AbstractFor microtunneling in hard rock, as it is encountered very often in alpine tunneling, the continuous further development of technologies plays a key role to overcome the limitations in drive length and to improve performance. During the last decades, the application range of slurry microtunneling has been considerably extended and more demanding projects have been designed for underground utilities installations worldwide, including many sewage tunnels and hydropower plants. The prevailing ground conditions still play a key role and determine the limits for alignment design and the possible use of trenchless construction methods. In hard rock conditions with high rock strength and/or abrasivity, the applicability of slurry microtunneling has been especially limited in the non‐accessible diameter range in the past. With the new AVN 800 HR for hard rock microtunneling, Herrenknecht has developed a machine concept, enabling drives of up to 200 m, with precise steering of the MTBM. Longer drives, even through hard rock, make microtunneling a more economic, flexible, and more environmentally friendly construction method. New opportunities for clients and consultants in the planning of tunnel routes in alpine environments for different infrastructure installations can be considered, making trenchless installations even more cost‐effective, while improving public acceptance.

Vehicle Turning Carbon Emissions and Highway Planar Alignment Design Indicators

The carbon emitted by vehicles traveling on curved roads is greatly affected by the alignment of the route, yet the mechanism behind this is not yet clear, leading to current horizontal alignment designs being unable to avoid this problem. To clarify the principles and indicator thresholds of low-carbon design for planar geometry, this study takes the carbon emission of traveling on curved routes as the research object, and establishes a relationship model between carbon emissions and design indicators based on the principles of vehicle dynamics and kinematics. Field tests were conducted to validate the quantitative relationship model. The model shows that both radius and superelevation are negatively correlated with carbon emissions, while the lateral force coefficient is positively correlated with carbon emissions. The contribution of radius to carbon emissions is greater than that of superelevation. This study clarifies the recommended values of low-carbon design indicators by assessing carbon emissions according to the current route design specification, outlines the principles of superelevation settings, and proposes a methodology to deal with the relationship between superelevation and the lateral friction coefficient. The research findings promote the quantification and standardization of low-carbon highway design, contributing to the early mitigation of high-carbon emissions from curved traffic during the design phase.

Rational synthesis of core/shell heterostructured quantum dots for improved self-powered photodetection performance enabled by energy band engineering

Colloidal quantum dots (CQDs), especially core-shell QDs, have attracted dramatic interests as emerging materials in optoelectronic devices due to their size tuneable band-gap, high absorption coefficient, facile and low-cost synthesis routing, etc. However, the precise design of core/shell band engineering along with charge carrier transfer efficiency are still challenging, inevitably impacting the performance of optoelectronic devices. Herein, three different types of CdSe/CdS core-shell heterostructured QDs have been obtained via a proposed synthesis strategy of adjusting the core size but fixing the shell thickness. The performance of the core-shell QDs based self-powered photodetectors can be efficiently regulated by the optimization of synthesis strategy with the design of energy band alignment. Compared to the quasi type-II and the type-I QDs devices, the Ilight/Idark ratio of type-II heterostructure based photodetector is increased by ∼2 and ∼5 orders of magnitude, respectively. The champion device exhibits extraordinary optoelectronic performance in terms of ultrahigh light-to-dark current ratio of 105, photoresponsivity of 10.64 mA/W, at bias of 0 V, respectively. The charge carrier dynamics and transfer mechanisms of the QDs were further investigated, revealing the improved carrier separation and transportation efficiency induced by a strong build-in electric field in type-II CdSe/CdS core-shell heterostructure. This work provides a new strategy for the next-generation self-powered QDs optoelectronics enabled by the proposed synthesis approach along with the design of energy band alignment.

Design of Traffic Control Solutions and Infrastructure Alignment to Overcome Congestion Problems in Batam City.

Batam City is one of the cities that experiences significant traffic congestion problems, especially around the Traffic Light intersection. This research aims to identify and analyze the factors that influence the smoothness of traffic at the Batam City Traffic Light Intersection, as well as designing integrated solutions to overcome these problems. Through study stages involving data collection, analysis of key factors causing traffic jams, and modeling the impact of each factor, this research tries to provide recommendations for improving infrastructure, redesigning intersections, using traffic light technology, and providing education to motorists. It is hoped that the results of this research can serve as a guide for the government and stakeholders in improving traffic management and quality of life in Batam City.

Force system of 3D-printed orthodontic aligners made of shape memory polymers: an in vitro study

ABSTRACT This study aimed to report forces and moments delivered by 3D-printed aligners. Tera Harz TC-85 resin and Zendura FLX (ZF) thermoformed sheets (0.76 mm) were used. Rectangular strip specimens (50 × 10 × 0.6 mm) were produced for a three-point bending test (3PB) at different temperatures. Full anatomical aligners were produced for 3D force measurements on different teeth and directions at 37 °C, using a custom-made device. ZF exhibited flexural forces between 1.7 and 2.3 N, while TC-85 from 0.3 N to 2.7 N, with temperature affecting TC-85 more significantly. At lower temperatures, TC-85 was stiffer than ZF, but at higher temperatures, it became less rigid. The 3D-force measurements indicated comparable values for both materials. Force ranged from 0.3–1.7 N and moment from 4.8–9.4 Nmm. The study concluded that TC-85 3D-printed aligners deliver biologically compatible forces for orthodontic movement and offer better control over thickness. Highlights The 3D-printed Tera Harz TC-85 resin revolutionises aligner production. Tera Harz TC-85 aligners generate forces within the orthodontic accepted range. Shape recovery of TC-85 can enable adaptability and larger incremental step size. The 3D printing offers greater control over aligner design and thickness.

The Coupling Mechanism between Railway Alignment Design and Resource Environment in the Southwestern Mountainous Areas of China

Faced with the characteristics of multifactor coupling and interweaving along the railway lines in the southwestern mountainous areas of China, researching the coupling mechanism and optimizing the collaborative development path between alignment designs and the resource environment is conducive to promoting the green and sustainable development of railways in these southwestern mountainous areas. In this study, first, regarding the environmental characteristics of engineering along the railway lines in the southwestern mountainous area, the key elements of the interaction and coercion between the alignment design (internal system) and the resource environment (external system) are identified, and the interactive impact mechanism of the “alignment design–resource environment” complex is revealed. Accordingly, a nonlinear coupling mechanism between the alignment design system and the resource environment system is established using the deviation coefficient coupling degree model. Second, from a methodological perspective, following a technical path of “analyzing the coercive effects of internal and external factors–identifying coupling relationships–discovering coupling laws–screening driving factors–proposing optimization plans–achieving collaborative development goals”, we propose an overall optimization plan to solve the problem. Finally, the Chengdu Changdu section of the X railway, which is located in a southwestern mountainous area, is taken as an example for this study. The results indicate that if the state of the external system of the KL scheme is continuously improved through the regulation of the u22 (crossing the ecological protection red line length), u23 (biodiversity impact), and u24 (ecosystem impact) indicators and that the internal structure of the line design is improved by optimizing the l12 (total length of bridges and tunnels) and l13 (number of stations) indicators, effectively driving the improvement in the u31 (land resource occupation) and u43 (land development intensity) indicators, the alignment design and resource environment will exhibit a mutually reinforcing coupling evolution trend and ultimately achieve an “alignment design–resource environment” composite system with higher quality coupling.

Energy-saving design of underground metro vertical alignment with deep reinforcement learning

The design of metro vertical alignment greatly affects train traction energy consumption. This study develops a deep reinforcement learning (DRL) algorithm for an energy-saving design of underground metro vertical alignment and analyzes the influence of train traction energy consumption calculation factors (CFs) on energy-saving design. First, a metro train operation simulation model is adopted using the approximate integral method, and the value range of CFs as input parameters is determined. Second, the 'agent', 'state', 'action', and 'reward' of the metro vertical alignment environment and the corresponding alignment constraints are determined. Third, a Dueling Double Deep Q Network (D3QN) is constructed to design the energy-saving metro vertical alignment. The proposed model is applied to a real-world metro case study, and the influence of CFs (design speed, limiting gradient in reverse slopes, and passenger capacity) on energy-saving design is analyzed. Finally, compared to manual design, the D3QN-based design outperforms GA-based design and DQN-based design, and demonstrates a remarkable energy savings of 6.17%.

Seepage interaction mechanism of crossing tunnels and existing tunnels: Model test and numerical analysis

High-density urban tunnel engineering produces strong spatial seepage and stability interactions of newly built and existing operational tunnels, which is critical to the safety and resilience of transport infrastructure. Previous research mainly focused on the mechanical response of adjacent tunnel construction and the active deformation control of surrounding rock, while little consideration is given to the influence of spatial intersecting tunnels on the seepage field distribution, especially in water-rich regions. This paper investigates the seepage interaction of crossing tunnels and existing tunnels using dedicated seepage tests and corresponding numerical analysis under different hydrodynamic head heights and spatial crossing forms. The schemes are designed based on the Kexuecheng Tunnel in Chongqing City, China, which is a typical small spacing highway tunnel that crosses five existing railway tunnels in complex hydrogeological environment. According to the results, the seepage funnels generated by intersecting tunnels will overlap each other in space, causing significant changes in the seepage field within the impact area. When the newly built tunnel above-crossing the existing tunnels, the water pressure on lining structure of the small interval tunnel can be reduced by 20 ∼ 30 %. While the impact of the existing tunnel on the seepage field of the new tunnel is mainly reflected in its upper part. The construction of new tunnels is equivalent to adding seepage paths to the upper or bottom of an existing tunnel, reducing its water pressure by 10 ∼ 30 %. The spatial overlap effect will significantly reduce the water pressure at the intersection of tunnels, but also exacerbates the asymmetric distribution of water pressure in small spacing tunnel. According to the W-shaped spatial distribution of the seepage field in small spacing tunnels, the predicted seepage influence range may exceed 80 ∼ 100 m. When the newly built tunnel above-crossing or under-crossing the existing railway tunnels, the water inflow of the small interval tunnel and the overlying tunnel can be decreased by 10 ∼ 30 % compared to the situation without crossing. However, the overall groundwater discharge further increases by 53.9 %. The seepage interactions of newly built tunnels and existing tunnels could provide support for both alignment design and construction of newly built tunnel, and service performance improvement of existing tunnels.

Biomechanics of clear aligner therapy: Assessing the influence of tooth position and flat trimline height in translational movements.

The present clear aligner therapy (CAT) research focuses on isolating and reporting the biomechanical performance for three separate teeth, three translational movements and two flat trimlines at different heights. By identifying key patterns, the research seeks to inform the development of improved aligner designs, ultimately enhancing the effectiveness of clinical orthodontic treatments. In an invitro setting using the Orthodontic Force Simulator (OFS), the biomechanical response of 30 aligners was investigated on three different teeth of a straight symmetric maxillary dentition (central incisor, canine and first molar). Each tooth was tested under two flat trimline conditions (trimmed at gingival margin, TL0; extended 2.0 mm below, TL2) and for three types of translational movements (palatal translation, mesial translation and intrusion). Forces and moments were reported at the centre of resistance for each displaced tooth as well as the two neighbouring teeth, evaluating a total of 18 distinct scenarios. Findings indicate significant variability in the biomechanical responses based on tooth location in the arch, trimline height and movement performed. For palatal translations, the palatal force required to perform the movement was observed highest in molar cases, followed by canine and incisor cases, with a notable difference in the distribution of side effects, indicating a strong influence of tooth anatomy and position in the arch. Similarly, in mesial translations and intrusions molars experienced greater forces and moments than the corresponding movements applied on canines and incisors, but uniquely dispersed for each configuration tested. Regarding the shape of the aligner, TL2 consistently showed improved control over orthodontic movements compared to TL0. Neighbouring teeth frequently displayed compensatory reactions up to about half of the intensity observed on the tooth being moved, with notable variations from case to case. This research supports fundamental factors impacting CAT: Characteristic patterns in the direction and intensity of forces and moments are associated with each of the three translational movements tested. Tooth anatomy and arch location significantly influence the biomechanical performance of aligners, with an observed trend for molars to display higher forces and moments over canines and incisors, but distributed differently. The height of a flat trimline, specifically TL2, shows enhanced control over orthodontic movements. Additional findings revealed a compensatory activity of neighbouring teeth, which varies based on tooth region and movement type. It potentially could influence CAT outcomes negatively and merits attention in future investigations. These results support a tailored CAT method that improves aligner design for better force application. This method needs to be used alongside, and confirmed by, clinical knowledge. Future research should extend these findings to a wider range of clinical conditions for greater applicability in the day-to-day orthodontic practice.

Biomechanical effects of clear aligner with different shape design at extraction space area during anterior teeth retraction.

This study aimed to investigate the biomechanical effects of clear aligner (CA) with different shape designs at extraction space (CAES) area during space closing. A finite-element method (FEM) model of mandibular dentition, periodontal ligaments, attachments, and corresponding CA was established. The connecting rod design of CAES was modelled for the control group. Eight test groups with different heights of CAES from -4 mm to +4 mm were designed. Tooth displacement tendencies were calculated. The maximum principal stress in PDLs, teeth, and CAs was analysed. Both global coordinate system and local coordinate system were also used to evaluate individual tooth movements. Across all groups, stresses concentrated on the lingual outer surface of CAESs. For the lowered CAES groups, both the stress value and the stress distribution area at CAESs were increased. The lowered CAES groups showed reduced movement in anterior teeth and less tipping tendency of the canines. The shape of CAES has a biomechanical impact on anterior teeth movement and should be considered in aligner design. The results suggest that increasing the height of CAES can enhance anterior teeth retraction, while lowered CAES may facilitate controlled root movement. Changes in the shape of CAES represent a potential direction for biomechanical improvement of clear aligner in extraction cases and are worth exploring.

Design of curvilinear sections in vertical alignment of roads and railways using general transition curves

Creation of road and railway routes in general and also design of vertical alignment in particular constitute an significant engineering problem. The vertical alignment of roads, and especially of railways, is of great importance for passenger comfort under high-speed driving conditions. This requires alignment smoothness to a greater extent. In practice, the dominant tendency is to consider vertical arcs as parabolic curves (quadratic or cubic). Other solutions have been also proposed and analyzed in the literature, thus providing an alternative approach to traditional methods. This paper describes a design method of vertical arcs using the so-called general transition curves. These curves describe the entire curvilinear transition between two straight lines using a single equation, and the curvature at the contact points with the straight lines is zero, which is of great practical significance in the light of vehicle motion dynamics. As a result, relevant research shows that general transition curves, compared to other curves, provide a more favorable distribution of lateral changes of acceleration. The paper deals not only with appropriate design procedures of a general nature, but also specific procedures of fitting vertical arcs to preset points. The methods for designing vertical arcs constitute a useful extension of available methods, and offer a valuable tool for engineers and designers of road and railway routes.

A Broadband Photodetector Based on Non-Layered MnS/WSe2 Type-I Heterojunctions with Ultrahigh Photoresponsivity and Fast Photoresponse.

The separation of photogenerated electron-hole pairs is crucial for the construction of high-performance and wide-band responsive photodetectors. The type-I heterojunction as a photodetector is seldomly studied due to its limited separation of the carriers and narrow optical response. In this work, we demonstrated that the high performance of type-I heterojunction as a broadband photodetector can be obtained by rational design of the band alignment and proper modulation from external electric field. The heterojunction device is fabricated by vertical stacking of non-layered MnS and WSe2 flakes. Its type-I band structure is confirmed by the first-principles calculations. The MnS/WSe2 heterojunction presents a wide optical detecting range spanning from 365 nm to 1550 nm. It exhibits the characteristics of bidirectional transportation, a current on/off ratio over 103, and an excellent photoresponsivity of 108 A W-1 in the visible range. Furthermore, the response time of the device is 19 ms (rise time) and 10 ms (fall time), which is much faster than that of its constituents MnS and WSe2. The facilitation of carrier accumulation caused by the interfacial band bending is thought to be critical to the photoresponse performance of the heterojunction. In addition, the device can operate in self-powered mode, indicating a photovoltaic effect.

The Distribution Law of Ground Stress Field in Yingcheng Coal Mine Based on Rhino Surface Modeling

The distribution law of the ground stress field is of great significance in guiding the design of coal mine roadway alignment, determining the parameters of roadway support, and preventing and controlling the impact of ground pressure in coal mines. A geostress inversion method combining Rhino surface modeling and FLAC3D 6.0 numerical simulation software is proposed. Based on the geological data of the coal mine and the results of on-site measurements, a three-dimensional geological model of Yingcheng Coal Mine is established for the geostress inversion, and the distribution law of the geostress field in Yingcheng Coal Mine is obtained. Research shows the following: (1) The horizontal maximum principal stress values of the Yingcheng Mine are between 33.9 and 35.3 MPa, the horizontal minimum principal stress values are between 23.6 and 25.4 MPa, and the direction of the horizontal maximum principal stress is roughly in the southwest to west direction; (2) the three-way principal stress magnitude relationship is σH > σv > σh, indicating that the horizontal stress dominates in the study area, which belongs to the slip-type stress state; (3) The maximum principal stress of No. 3 coal seam is 33.1–34.8 MPa, the middle principal stress is 27.5–29.2 MPa, and the minimum principal stress is 17.3–22.9 MPa. Due to the influence of topography and burial depth, there is a phenomenon of stress concentration in some areas. By comparing the inversion values with the measured values, the accuracy of the geostress inversion is high, and the initial geostress inversion method based on Rhino surface modeling accurately inverts the geostress distribution pattern of the Yingcheng coal mine.

Research on traffic accident prediction of expressway tunnel based on B-NB model

Objective The study investigates the relationship between traffic accidents in expressway tunnels and their influencing factors, with the aim of predicting traffic accidents within tunnels and presenting reasonable recommendations to improve tunnel safety. Methods The study utilizes a dataset of 586 traffic accidents occurring exclusively within 8 tunnels along a Guangdong Province expressway from 2017 to 2021. It applies the geometric alignment consistency principle to segment road sections, defines tunnel boundaries based on driving behavior, and employs a Bayesian-modified negative binomial regression model (B-NB model) to identify 6 significant variables from a pool of 17 factors. Results The predictive performance of the B-NB model demonstrated similarities to that of the fixed parametric model. This outcome might be attributed to the chosen prior distribution settings and the limited amount of data. Nonetheless, the model effectively captures relationships among variables, leading to improved accuracy in accident prediction and the predictive model achieves a 76.1% accuracy rate. Conclusions Drawing from the estimation results, practical measures are suggested across three dimensions: road geometric alignment design, tunnel traffic safety facilities, and traffic emergency management. These proposals aim to ameliorate the severe consequences of tunnel accidents. Future research will explore an in-depth comparison of estimation results, considering the impact of time and variable correlation on the prediction model by expanding the existing data. This will guide the direction of subsequent research endeavors.

Simulation of Water Flow Path Length (WFPL) and Water Film Depth (WFD) for Wide Expressway Asphalt Pavement

This paper simulates actual rainfall conditions and raindrops flowing to form a water flow path (WFP) on the pavement surface of the wide expressway. Then, the different linear combination conditions, including longitudinal slope (LS), transverse slope (superelevation, TS), gradual change rate of TS, and pavement width (PW), were simulated and analyzed. The results show that (1) the influence of each linear index on the maximum water film path length (WFPLmax) and maximum water flow depth (WFDmax) differs (according to the absolute values of Beta, LS has the greatest influence on WFPLmax, and PW has the greatest influence on the WFDmax for both straight-line and circular-curve sections); (2) when the design value of LS is between 1.1% and 4%, the WFDmax can be effectively reduced by lowering the value of LS; (3) in the case of a high design value of LS, it can be considered to increase the TS of the pavement arch from 2% to 2.5% to effectively reduce the WFPLmax, and the wider PW, the better the reducing effect; (4) while widening the expressway, adjusting the TS from 2% to 2.5% can effectively offset the increasing effect of PW on the WFDmax. This research aims to fill the research gap in the simulation of runoff characteristics of wide expressway asphalt pavements and to improve the alignment design of expressways from the drainage perspective for the improvement of driving safety.

Differences in Trochlear Morphology of a New Femoral Component Designed for Kinematic Alignment from a Mechanical Alignment Design.

Because kinematic alignment (KA) aligns femoral components in greater valgus and with less external rotation than mechanical alignment (MA), the trochlear groove of an MA design used in KA is medialized, which can lead to complications. Hence, a KA design has emerged. In this study, our primary objective was to quantify differences in trochlear morphology between the KA design and the MA design from which the KA design evolved. The KA and MA designs were aligned in KA on ten 3D femur-cartilage models. Dependent variables describing the morphology of the trochlea along the anterior flange, which extends proximal to the native trochlea, and along the arc length of the native trochlea, were determined, as was flange coverage. Along the anterior flange, the KA groove was significantly lateral proximally by 10 mm and was significantly wider proximally by 5 mm compared to the MA design (p < 0.0001). Along the arc length of the native trochlea, the KA groove was significantly lateral to the MA design by 4.3 mm proximally (p ≤ 0.0001) and was significantly wider proximally by 19 mm than the MA design. The KA design reduced lateral under-coverage of the flange from 4 mm to 2 mm (p < 0.0001). The KA design potentially mitigates risk of patellofemoral complications by lateralizing and widening the groove to avoid medializing the patella for wide variations in the lateral distal femoral angle, and by widening the flange laterally to reduce under-coverage. This information enables clinicians to make informed decisions regarding use of the KA design.

Highway Alignment Optimization Design Method Based on Multi-Objective Particle Swarm Optimization

Highway alignment design is a nonlinear multi-objective optimization problem. Due to the uncertainty and complexity of the constraints, it is challenging to develop a suitable model for 3D road alignment design. To comprehensively consider the constraints and realize the intelligent design, this study puts forward a novel highway alignment model to optimize the horizontal and vertical alignment design, in which the length utility cost and structure construction cost are projected into the optimization space. Finally, the numerical solution is carried out by MOPSO on MATLAB platform. The results show that this method can effectively solve the problem of highway alignment design under the condition of realizing the highway design specifications, shortening the design cycle, and improving the design quality, which verifies the feasibility of the optimization algorithm for the horizontal and vertical alignment optimization design of highway.

Research on optimization design of highway route alignment based on vehicle operating speeds

Research on optimization design of highway route alignment based on vehicle operating speeds