Search Results (35)

The design of nanoscale electronic components remains a major challenge because we have limited control over the chemical and physical properties of their molecular constituents. Even subtle structural or compositional modifications can significantly alter their electronic behavior. Consequently, updating a molecular component often necessitates developing a new model from scratch. In this study, we present a comprehensive analysis of the rectification properties of a promising molecular diode initially proposed by Aviram and Van Dyck. The model has been systematically decomposed into fundamental building blocks, enabling the electron transport process to be examined both as an integrated event and as a sum of cooperative interactions. Our findings reveal that certain motifs—such as the D-σ-A architecture—play a significant role in rectification. However, achieving high-performance molecular rectifiers also requires cooperative interplay with other structural elements that contribute to rectification, such as asymmetric molecule–metal contacts. In this study, we conduct a detailed investigation of the roles these elements play in shaping the rectifying characteristics, and we further interpret their effects by analyzing the dominant transport channels under forward and backward bias conditions. This deeper understanding of the transport mechanism offers greater control over the system and opens the door for rational design strategies for improving rectification efficiency in future molecular devices. Full article

To address the issue of structural tilting caused by uneven foundation settlement in soft soil areas, this study combined a specific engineering case to conduct numerical simulations of the rectification process for an inclined reinforced concrete building using ABAQUS finite element software. Micropile-raft combined jacking technology was employed, applying staged jacking forces (2400 kN for Axis A, 2200 kN for Axis B, and 1700 kN for Axis C) with precise control through 20 incremental steps. The results demonstrate that this technology effectively halted structural tilting, reducing the maximum inclination rate from 0.51% to 0.05%, significantly below the standard limit. Post-rectification, the peak structural stress decreased by 42%, and displacements were markedly reduced. However, the jacking process led to a notable increase in the column axial forces and directional changes in beam bending moments, reflecting the dynamic redistribution of internal forces. The study confirms that micropile-raft combined jacking technology offers both controllability and safety, while optimized counterforce pile layouts enhance the long-term stability of the rectification system. Based on stress and displacement cloud analysis, a monitoring scheme is proposed, forming an integrated “rectification-monitoring-reinforcement” solution, which provides a technical framework for building rectification in soft soil regions. Full article

This study investigates a risk-based approach to evaluate the effectiveness of sprinklers in residential buildings to offset the risk premium imposed by combustible cladding (expanded polystyrene and aluminium composite panels) installed on such buildings in Victoria, Australia. This approach builds upon the Initial Fire Spread in Cladding Assessment Number (IF-SCAN), a concept pioneered by Cladding Safety Victoria as a triage tool in their rectification program. The analysis uses published data from real fires in buildings with and without sprinkler systems installed. It considers three criteria: death rates, injury rates, and construction cost. The construction cost was determined using an existing costing model currently employed in Victoria. The results of this study suggest a higher risk tolerance can be accepted for combustible cladding on buildings equipped with sprinkler systems over that set out in government policy. More specifically, it was found that a building fully protected by sprinklers can generally counterbalance the fire risk posed by combustible cladding spanning up to seven apartments, while a span of up to ten apartments could be considered for buildings without balconies or a private courtyard. Full article

Prefabricated prefinished volumetric construction (PPVC) is a relatively new technique that has recently gained popularity for its ability to improve flexibility in scheduling and resource management. Given the modular nature of PPVC assembly and the large amounts of visual data amassed throughout a construction project today, PPVC building construction progress monitoring can be conducted by quantifying assembled PPVC modules within images or videos. As manually processing high volumes of visual data can be extremely time consuming and tedious, building construction progress monitoring can be automated to be more efficient and reliable. However, the complex nature of construction sites and the presence of nearby infrastructure could occlude or distort visual data. Furthermore, imaging constraints can also result in incomplete visual data. Therefore, it is hard to apply existing purely data-driven object detectors to automate building progress monitoring at construction sites. In this paper, we propose a novel 2D window-based automated visual building construction progress monitoring (WAVBCPM) system to overcome these issues by mimicking human decision making during manual progress monitoring with a primary focus on PPVC building construction. WAVBCPM is segregated into three modules. A detection module first conducts detection of windows on the target building. This is achieved by detecting windows within the input image at two scales by using YOLOv5 as a backbone network for object detection before using a window detection filtering process to omit irrelevant detections from the surrounding areas. Next, a rectification module is developed to account for missing windows in the mid-section and near-ground regions of the constructed building that may be caused by occlusion and poor detection. Lastly, a progress estimation module checks the processed detections for missing or excess information before performing building construction progress estimation. The proposed method is tested on images from actual construction sites, and the experimental results demonstrate that WAVBCPM effectively addresses real-world challenges. By mimicking human inference, it overcomes imperfections in visual data, achieving higher accuracy in progress monitoring compared to purely data-driven object detectors. Full article

One method of rectifying tilted buildings is by lifting them unevenly using hydraulic jacks. These jacks are loaded both monotonically and cyclically during the rectification process. It has been shown that the change in jack length is the sum of the change in the piston slide out and the change in the jack’s cylinder length, which is supported by a parallelepiped element. Laboratory tests were conducted to investigate the piston slide out and the change in the jack’s cylinder length under both monotonically and cyclically loaded conditions. The results indicated that the piston slide out forms a hysteresis loop. In contrast, the change in the jack’s cylinder length does not exhibit a hysteresis loop and is a non-linear function of the load. A structural model of the jack was proposed, consisting of three components: a linearly elastic component connected in parallel to the component where the frictional force occurs, and a component with non-linear elastic characteristics connected in series with them. Displacements of the linear elastic component, characterized by a constant stiffness, occur as long as the external load exceeds the internal frictional force. The value of the frictional force in this model increases with the load. The stiffness of the non-linear elastic component increases proportionally to the load. Full article

There are many complex and uncertain factors in the process of building rectification and reinforcement that can easily lead to construction quality failures. This study develops a novel hybrid risk analysis approach to perceive the construction quality risk under uncertainty by integrating the extension theory (ET), the cloud model (CM), the Dempster–Shafer (D-S) evidence theory and the dynamic Bayesian network (DBN). The extended cloud model (ECM) combining the ET and the CM is not only effective in avoiding information loss, but is also capable of dealing with the ambiguity and randomness in risk assessment. The ECM is employed to construct the basic probability assignments (BPA) of risk factors across different risk states. The improved D-S evidence theory considering the expert importance coefficient is used for the fusion of expert judgments. A DBN model integrating monitoring indicators is established to predict the dynamics of overall quality risk during rectification and reinforcement. Then, the measured data of settlement difference and settlement rate are fed back to the DBN model to update the risk assessment results in real time. Finally, a case study of the rectification and reinforcement in a high-rise building is taken to verify the feasibility and validity of the developed risk analysis approach. The risk assessment results better reflect the unexpected risk events in actual construction. The proposed approach provides a research paradigm for quality risk assessment of similar rectification and reinforcement projects. Full article

Due to the rising prices of houses and rent, apartment buildings have become the preferred and most utilized dwellings in Australia. However, there have been cases of serious defects in multi-unit dwellings (apartment buildings), posing various risks to and reducing potential residents’ confidence in such dwellings. To address this issue, the current study investigated the types, causes, risk severity, and impacts of defects on residents in mid- to high-rise multi-unit dwellings in Australia. The study utilized a mixed approach involving quantitative (online questionnaire) and qualitative (interviews) methods. Data were collected from 104 apartment building residents in Brisbane, Queensland, Australia, with support from interviews with six experienced local construction professionals. The results revealed that there are 11 key defects present in local apartment buildings, with waterproofing, internal finishes, and structural issues being the most frequently reported. Residents typically report these defects to building owners, agents, and managers, who take more than three months, on average, to rectify them, adding to the residents’ psychological issues and their inability to use the property as intended. The reasons for the delayed rectification of defects include non-responsive owners, agents, and building management teams, scheduling conflicts, litigation, and high costs. The interviewed professionals acknowledged the presence of defects and identified the reliance on Design and Construct (D&C) and fixed price contracts, lack of public awareness, and absence of a system to capture builders’ reputation, as well as a manipulative quality check system, as key reasons for defects. This study addresses the defect concerns in multi-unit Australian dwellings (apartments) and expects to spark a much-needed debate around reforms in the construction sector to address these issues and minimize their risks and impact on residents. Full article

The application of BIM technology in building construction provides the possibility to realize design accuracy, to visualize the construction details, to optimize construction schemes, and to enhance cooperation among various professionals. The Yancheng Nanyang Airport terminal 2 project, with its large span of steel roof structure, complex installation in mechanical and electrical pipeline (MEP) engineering, and difficulty in construction organization, is taken as the engineering background. The whole process application of BIM technology in the construction process is introduced. In structural engineering construction, the application of BIM technology can provide guidance for plane layout of the construction site, and can also assist in deepening the designs of irregular steel components. In steel construction, the application of BIM technology gives a commendable visual demonstration of the construction process of the metal roof system and the single-layer reticulated shell. In MEP engineering, the application of BIM technology provides a great approach to establish a synthesis of pipeline drawings to further form pipeline section diagrams and operation drawings. By integrating the dimension of time, precision control, and deviation rectification, a recursive construction drawing can be built. With respect to synergistic management, the quality and safety management in the construction site can be implemented on the basis of BIM terminal equipment as well. This paper will give a great reference on the application of BIM technology in the airport terminal construction. Full article

Recent approaches for fast semantic video segmentation have reduced redundancy by warping feature maps across adjacent frames, greatly speeding up the inference phase. However, the accuracy drops seriously owing to the errors incurred by warping. In this paper, we propose a novel framework and design a simple and effective correction stage after warping. Specifically, we build a non-key-frame CNN, fusing warped context features with current spatial details. Based on the feature fusion, our context feature rectification (CFR) module learns the model’s difference from a per-frame model to correct the warped features. Furthermore, our residual-guided attention (RGA) module utilizes the residual maps in the compressed domain to help CRF focus on error-prone regions. Results on Cityscapes show that the accuracy significantly increases from $67.3\%$ to $71.6\%$, and the speed edges down from $65.5$ FPS to $61.8$ FPS at a resolution of $1024\times 2048$. For non-rigid categories, e.g., “human” and “object”, the improvements are even higher than 18 percentage points. Full article

The THz pulse of a few picosecond durations have been generated and detected via optical rectification and electro-optic effect within the same ZnTe crystal. An unbalanced single-shot detection scheme was performed to characterize the signal. As a result, a multicycle signal was obtained, in which two-photon absorption and other associated nonlinear effects were reportedly negligible. The experimental set-up is compact, economical, easy to build and has the added simplicity of facilitating an independent analysis of the horizontal or vertical polarization arm of the THz-modulated chirped probe beam. This work finds a useful application in integrated THz devices, narrow-band THz phonon spectroscopy and spectroscopic investigation of fast-occurring processes. Full article

Tilting of buildings due to uneven settlement, construction quality issues or other problems is one of the critical accidents threatening the safety of buildings. In order to determine a reasonable solution with respect to the rectification of the tilting building, detection of the stresses of the substructure is necessary. In this study, a stress release method to test the stress of prefabricated pipe pile under loading is studied by combining experimental research and finite element numerical simulation. Based on various measurements, such as traditional strain gauges, vibrating wire strain gauges, and three-dimensional digital image correlation (DIC) tests, the relationship between local residual stress and actual stress of the slotted area at different load levels is determined. Meanwhile, the stress release process in slotted precast pipe pile was numerically simulated with ABAQUS to investigate the influence of the slotting dimension parameters on the stress release rate at different load levels. Based on 1042 sets of finite element modeling results of multi-parameter combination, the quantitative relationship between slot width, depth, spacing, prestress level and stress release rate is studied. An explicit prediction model of the stress release rate is given by regression analysis of combined test results and simulation data. With the prediction model, the stress condition of a loaded precast pipe pile can be accurately predicted based on low-loss slotting. Compared to the traditional stress release method, the proposed method has better controllability and applicability, less damage to the structure, and stronger anti-disturbance ability. Full article

In this study, we aimed to further the international discussion on the methodology of applying GIS technology to the editing of large-scale cadastral maps, taking the experience of editing the cadastral map of Toruń from 1910–1915 as an example. We present the concept of building a georeferential spatial database of topographic–historical objects (GSDoT-HO), which includes the stages involved in creating the database, its exemplary structure, and a proposal of good practices in this process, which were developed in the course of previous projects using a geographic information system for Historical Atlases of Polish Towns. Our works included the scanning, calibration, and rectification of a total of 178 sheets of cadastral maps (including 154 sheets of the map of Toruń and 24 sheets of the cadastral map of the then-village of Mokre) at differentiated scales of 1:250, 1:500, 1:1000, and 1:2000. Finally, in the process of vectorization, vector and attribute data were acquired, which made up the final result in the form of GSDoT-HOs. This database was created out of seven information layers with linear or polygon geometries, including the two most important layers, i.e., plots and buildings, which for the then-area of the city of Toruń, contained approximately 5800 and 10,800 vectorised polygon objects, respectively. This article shifts the focus of the discussion of standards in the use of GIS technology to edit Historic Towns Atlases from the development of interactive maps to the construction of a database that should enable comparative studies of urban spaces. Full article

When a network is attacked, the network controllability decreases and the network is at risk of collapse. A network with good controllability robustness can better maintain its own controllability while under attack to provide time for network recovery. In order to explore how to build a network with optimal controllability robustness, an exhaustive search with adding edges was executed on a given set of small-sized networks. By exhaustive search, we mean: (1) All possible ways of adding edges, except self-loops, were considered and calculated at the time of adding each edge. (2) All possible node removal sequences were taken into account. The nested ring structure (NRS) was obtained from the result of the exhaustive search. NRS has a backbone ring, and the remaining edges of each node point to the nearest nodes along the direction of the backbone ring’s edges. The NRS satisfies an empirically necessary condition (ENC) and has great ability to resist random attacks. Therefore, nested edge rectifcation (NER) was designed to optimize the network for controllability robustness by constructing NRS in networks. NER was compared with the random edge rectification (RER) strategy and the unconstrained rewiring (UCR) strategy on synthetic networks and real-world networks by simulation. The simulation results show that NER can better improve the robustness of network’s controllability, and NER can also quickly improve the initial network controllability for networks with more than one driver node. In addition, as NER is executed, NRS gains more edges in the network, so the network has better controllability robustness. NER will be helpful for network model design or network optimization in future. Full article

Due to the virtues of low-cost and high positioning accuracy, Single-Frequency Precise Point Positioning (SF-PPP) is becoming a prospective technique. However, SF-PPP is not as widely used as dual-frequency and triple-frequency PPP at present, owing to the effect of ionospheric delay residuals after model rectification. In recent years, with the evolution of multi-constellation Global Navigation Satellite Systems (multi-GNSS, i.e., GPS, BDS-2, and BDS-3), it has become possible to obtain credible and continuous positioning results using SF-PPP. However, such performance would be significantly degraded in challenging environments (i.e., boulevards, tunnels, and tall buildings). Under these circumstances, GNSS signals are obstructed, and it is difficult to provide sufficient observations for SF-PPP. Therefore, the Inertial Navigation System (INS) is employed to promote the positioning performance of SF-PPP. The PPP/INS integration is regarded as one of the most efficient approaches in GNSS-denied environments. To satisfy the request of supplying real-time positioning information, the Real-Time Services (RTS) of the International GNSS Service (IGS) provide real-time precise orbit and clock products for globally distributed users through the internet. In this paper, a real-time GPS/BDS-2/BDS-3 SF-PPP and INS tight integration model is proposed, and it is assessed using the data gathered by vehicle and real-time products afforded by CAS (Chinese Academy of Sciences), GFZ (Deutsche GeoForschungsZentrum), and WHU (Wuhan University). The outcomes illustrate the following: (1) GPS + BDS SF-PPP/INS can provide more accurate and continuous positioning solutions compared with those of GPS + BDS SF-PPP, with improvements of 52.8%, 31.1%, and 42.8% in the north, east, and vertical components, respectively. (2) In general, the orbit and clock products’ accuracies in terms of GPS afforded by the three analysis centers are consistent with each other. For BDS, the orbit product from WHU is more accurate compared to those of CAS and GFZ. However, the accuracy of the clock product afforded by WHU is lower compared with those provided by the other two centers, especially for BDS-2 satellites. (3) The positioning accuracy in terms of Root Mean Square (RMS) values based on GFZ products are much higher than the results based on CAS and WHU products in the three directions. Full article

This paper describes a method for metric recording based on spherical images, which are rectified to document planar surfaces. The proposed method is a multistep workflow in which multiple rectilinear images are (i) extracted from a single spherical projection and (ii) used to recover metric properties. The workflow is suitable for documenting buildings with small and narrow rooms, i.e., documentation projects where the acquisition of 360 images is faster than the traditional acquisition of several photographs. Two different rectification procedures were integrated into the current implementation: (i) an analytical method based on control points and (ii) a geometric procedure based on two sets of parallel lines. Constraints based on line parallelism can be coupled with the focal length of the rectified image to estimate the rectifying transformation. The calculation of the focal length does not require specific calibrations projects. It can be derived from the spherical image used during the documentation project, obtaining a rectified image with just an overall scale ambiguity. Examples and accuracy evaluation are illustrated and discussed to show the pros and cons of the proposed method. Full article