Investigation for Developing 3D Concrete Printing Apparatus for Underwater Application

Underwater structures are crucial for national economic and social development. However, because of their complex environment, they are susceptible to damage during service. This damage should be prevented to minimize casualties and economic loss. Therefore, this study investigates the problems of disease identification and area statistics of underwater structures. To this end, the Dark‐Retinex (DR) algorithm that can enhance the image of underwater structure defects is proposed. The algorithm consists of a combination of a dark channel algorithm and the Retinex algorithm. This study analyzes the current research status of underwater image processing technology, designs the overall framework of the DR algorithm, and uses the underwater structure disease image to verify the algorithm. Comparing the effect of the image with only the dark channel defogging and DR algorithm processing, the DR algorithm is observed to achieve “defogging” processing of underwater structural disease images to achieve better enhancement effects. Moreover, for accurate disease area statistics, the binary morphology and optimal threshold segmentation theories are combined to perform disease edge screening and remove interference information. Finally, accurate statistics of the proportion of diseased pixels are achieved, as well as the quantitative detection of surface diseases of underwater structures. After actual operational verification, the improved image dehazing and parallel boundary screening algorithms can achieve better application results to detect underwater structure defects and disease statistics. The objective evaluation shows that the DR algorithm facilitates image processing, can obtain relatively high‐quality target images, and can solve the problems of time‐consuming and labor‐intensive detection of underwater structures, with significant risks and limitations. This helps pave the way for (1) the actual engineering of surface structure detection of underwater structures, (2) future storage in the database and assessment of hazard levels, and (3) a guide for engineering technicians to take corresponding maintenance measures.

A pulsed-laser ablation method for non-contact experimental vibration analysis of completely submerged underwater structures is proposed. Although impact testing with an impulse hammer is commonly used for vibration analysis due to its simplicity, impact testing has limited use in underwater conditions. An input-detection-free frequency response function measurement in water will greatly contribute to the development of high-precision and high-speed positioning autonomous underwater vehicles, underwater vehicle-manipulators, underwater robots, submarines, etc., which are used in dangerous conditions (e.g., deep oceans, under ice, and nuclear reactor plants). To achieve these high-performance underwater systems, vibrations due to hydrodynamic parameters (such as added mass, buoyant force, drag force, and damping coefficient) should be suppressed, and vibration tests should be conducted on the actual equipment submerged in water. The proposed method yields the frequency response function by applying a pulsed-laser-ablation excitation force to an underwater structure and measuring the output using a laser Doppler vibrometer. Because the direction, strength, and effective duration of the pulsed-laser-ablation force are essentially constant, this force can be estimated by measuring these properties in advance. Hence, the proposed method realizes input-detection-free frequency response function measurements in underwater conditions.

Diver and submersible navigation using acoustic techniques in and around complex underwater structures such as drilling and production platforms is complicated by the effects of multipath acoustic propagation. The research described in this paper is concerned with the investigation of techniques to overcome such effects, thereby leading to navigation systems which yield accurate locations of divers and submersibles operating within the core of the underwater structure. Several strategies are being studied including fixed transponder systems placed at prescribed locations in the structure and systems with tracking pencil-beams. The paper describes a computer simulation of a representative underwater structure which was developed for the study of the interaction between structural members and propagating acoustic beams generated by transponders mounted on and around the structure. It evaluates the detection probability of a diver or submersible operating within the structure as a function of acoustic source coordinates and yields information on optimal placement of acoustic sources and gives additional insight into the nature of the multipath transmission effect. INTRODUCTION A requirement exists for systems which can facilitate accurate navigation and location of divers or RCVs within the vicinity of offshore structures to allow routine inspection and maintenance. 1,2 Currently available short base-line or long base-line transponder oriented navigational systems 3 cannot be directly employed as they rely entirely on line of sight communication Transponder navigation systems compute locations on the basis of time-elapse measurements which are only valid along straight line paths. Within an off-shore structure, with its multiple structural members, signals to and from omni-directional transponders will be heavily corrupted by multipath transmission effects due to multiple reflections from various members, as well as by additive acoustic noise interference which may be both random and impulsive in nature, and will lead to ambiguous computations of distance based purely on time elapse measurements. A system which can be considered as more reliable in the underwater environment of the offshore structure than an omni-directional transponder system is an Inertial Navigation System. However two factors militate against such a system being employed for diver/RCV support. The first is cost, the second is gyroscopic drift which requires frequent compensation, and is particularly critical in the Azimuth gyroscope. This paper presents details of research being conducted at Strathclyde University towards the development of an accurate and reliable acoustic navigation system which employs some novel techniques of analysis, signal processing, and simulation to overcome the disadvantages outlined above. Several different strategies for system configuration and diver location are being currently pursued. After a discussion of some of these strategies, which are based on the location of sensors, results on the optimisation of these locations for representative offshore structures will be covered, and an ensuing measure of performance probability of detection for varying numbers of sensors-will be developed. The work on optimisation of sensor location and the attendant detection probabilities is extremely important as it leads to a reliable and robust system configuration for any specified offshore structure.

In order to flexibly monitor the underwater structure in the complex underwater environments, a small multi-thrusters AUV (Autonomous Underwater vehicle) has been designed with the attitude fusions of monocular vision and IMU (Inertial Measurement Unit). The tasks for detecting the surface faults of the underwater structures in designated area, such as large vessel propellers and offshore oil rig, determine the functional requirements of underwater image processing, flexible attitude control and autonomous navigation for AUV. In this paper, we present a novel design scheme of AUV, including the AUV hardware platform, the corresponding hydrodynamic model for “SAIL”, and the modified attitude fusion algorithm based on monocular vision and IMU. Finally, the experiments are carried out to evaluate the performances of the AUV.

The integrate of underwater structure of dams and bridges are very important for the safety of the projects. However, due to the complex flow field near the underwater structure, it is a challenge for the underwater robot to maintain stable near the underwater structures when performing inspection tasks. Moreover, it is difficult for underwater robots to absorb on the surface of underwater structures due to rough surface. This paper proposes a design of an adsorption track wheel for underwater wall-climbing robot, which combines the swirl suction cup and track wheel. The relationship between the water flow velocity, the wall gap and the suction cup adsorption force are analyzed. The influence of the surface curvature diameter of the structure and the diameter of the suction cup on the suction force is explored, and the structure of the suction cup is optimized to resist the influence of the water flow on the suction cup as much as possible while considering the flow velocity. After the suction cup improved, a prototype is designed and built. The final experiment demonstrates that the track wheel can provide sufficient adsorption force and friction force, which helps the structure to resist the water flow velocity up to 2.5m/s. Finally, it proposes the track wheel prototype can provide stable adsorption on the surface of underwater buildings for complex flow field.

Arc Welding With Industrial Robots in Small and Medium Batch Production A Procedure for Planning Industrial Robot Welding Systems

건축공사에서 지하공사는 주공정으로 전체공기와 공사비에서 큰 부분을 차지하고 있으며, 특히 도심지의 경우 해마다 규모가 증가하고 있다. 현재 현장에서 시공하는 지하옹벽은 많은 기능 인력이 필요하고, 공사기간 측면에서도 불리한 유로폼+솔져시스템에 의하여 공사가 진행되고 있다. 따라서 본 연구에서는 토목공사 현장에서 일부 사용되고 있는 무지주 거푸집을 기초로하여 건축공사에 적용 가능한 무지주 거푸집을 개발하였다. 또한 거푸집의 크기를 가정하여 건축공사 현장에서 가장 많이 사용되는 유로폼+솔져시스템과 경제성 측면에서 비교.분석하였다. 연구 결과, 합성 무지주 거푸집은 유로폼+솔져시스템에 비해 공사비가 약 9%높게 나타났으며, 비합성 무지주 거푸집은 약 9%낮게 나타났다. 하지만 합성 무지주 거푸집의 경우 구조체공사에서 콘크리트와 철근의 물량이 현저히 감소하여, 기존옹벽 시공가격 보다 약 35% 경제적 원가절감 효과를 볼 수 있다. In an architectural construction, underground construction is a critical path forming a major part of the total construction period and cost, and particularly in big cities, its size has been increasing every year. A basement wall currently constructed in the field needs a large functional work force, and the construction is under progress by the Euroform and Soldier system, which is disadvantageous in terms of the construction period. Therefore, in this research, non-supporting forms which are applicable to the buildings construction were developed, based on the non-supporting forms partly used in some civil engineering works. In addition, the size of a form was assumed and its economical efficiency was compared to that of the Euroform and Soldier system which is used most in construction fields, and the results were analyzed. The study results showed that the construction cost of composite non-supporting forms was higher than that of the Euroform and Soldier system by about 8%, and the construction cost of non-composite non-supporting forms were lower than that of the Euroform and Soldier system by about 9%. However, in the case of composite non-supporting forms, the amount of concrete and reinforcing rods remarkably decreased in structural construction, so it has the effect of an economical cost reduction compared to the construction cost of existing walls by about 35%

This paper comprehensively summarizes and discusses the latest research progress in the underwater concrete structure damage repair technology of infrastructures. The prompt application of underwater concrete structure repair technology can effectively deal with the damaged parts of underwater concrete structures, and it can ensure the safe and stable operation of infrastructure and extend its service life. Firstly, this study uses bibliometric methods to analyze the characteristics of the literature on research into underwater concrete repair in the past 30 years (1993–2023), and expounds the research status and hotspots of this field. Then, we conduct a comprehensive classification and discussion of the underwater concrete structure damage repair technologies at the current stage. This technology can be divided into two major types: direct underwater type and dry environment type. Further, the development history of these technologies is systematically sorted out and, combined with practical engineering application cases, the operation processes, applicability, limitations, and economy of these technologies are analyzed. Finally, the challenges and future development trends of the current underwater concrete structure damage repair technology are pointed out, which provides a direction for future research on the intelligent maintenance of underwater concrete structures.

Marine and underwater structures, such as seawalls, piers, breakwaters, and pipelines, are particularly susceptible to seismic events. These events can directly damage the structures or destabilize their supporting soil through phenomena like liquefaction. This review examines advanced numerical modeling approaches, including CFD, FEM, DEM, FVM, and BEM, to assess the impacts of earthquakes on these structures. These methods provide cost-effective and reliable simulations, demonstrating strong alignment with experimental and theoretical data. However, challenges persist in areas such as computational efficiency and algorithmic limitations. Key findings highlight the ability of these models to accurately simulate primary forces during seismic events and secondary effects, such as wave-induced loads. Nonetheless, discrepancies remain, particularly in capturing energy dissipation processes in existing models. Future advancements in computational capabilities and techniques, such as high-resolution DNS for wave–structure interactions and improved near-field seismoacoustic modeling show potential for enhancing simulation accuracy. Furthermore, integrating laboratory and field data into unified frameworks will significantly improve the precision and practicality of these models, offering robust tools for predicting earthquake and wave impacts on marine environments.

Multi-variety and small batch production is one type of mainstream production methods. Currently, methods of enterprise risk warning have been abundantly researched by scholars, but the effect of its application to the multi-variety and small batch manufacturing practices is not ideal. In this stud y, the authors apply the transductive support vector machine and active learning to the study of enterprise risk and early warning methods. The experiment utilizes real-world enterprise data and demonstrates that this method may meet the practical needs of the enterprise risk early warning systems and contributes to solving problems of multi-variety and small batch manufacturing operations.

한옥에서 축부는 건물의 외관과 실내 환경, 공사기간 및 공사비와 밀접한 관련을 지닌 부분이다. 본 연구에서는 전통적인 시공법을 분석하여 전통 한옥의 장점으로서의 특성을 유지하면서 개선된 한옥 축부의 시공법을 제안하였다. 그 개선안은 기성품의 사용, 전체 공정의 건식 조립공법화, 기둥과 벽체의 일괄 시공, 기밀성과 단열성능 향상 등의 특성을 지닌다. 앞으로 시제품의 제작과 성능 시험 등의 단계를 거쳐야 하겠지만 한옥의 형태적 특성을 유지하면서 공사기간과 공사비를 줄이는데 일조할 수 있을 것으로 기대한다. Wall of hanok is related to exterior, inner environment, and the period and cost of construction. This study analyzes traditional wall execution method and suggests improved one. The characters of the improved execution method are use of ready made goods, application of dry and prefabricated method and improvement of airtightness and insulation capacity etc. The result of this study needs production of pilot productions and tests of capacity. But this new method will be useful to save the period and cost of hanok construction.

The consumer market ever more calls for diversified products in small batches and the industry lacks production systems that meet the demands with efficiency and ability to adapt quickly. Integrated manufacturing systems implemented have their management for programmable logic controllers and electrical interconnections, control logic and satisfactory robustness, but they do not attend the needs of diversity and flexibility in production. The solutions to these needs refer the company to migrate to the use of new technologies of control, circuit and logic. But, for an industry migrates is a very big and expensive step. Then, there is an urgent need for methods that implement the interface between logic controllers and multi-agent systems in order to evolve an integrated manufacturing system taking advantage of all electrical circuitry, control logic and the logic controller that installs itself, taking advantage of the self-adapting characteristics that the multi-agent systems provide.

The paper proposes a new approach as an alternative to full automation of processes that meets current economic trends — collaborative multi-agent systems. In this concept, people and robots are considered as agents in a single sensory-information field, who perform tasks to achieve the goals of the collaborative multi-agent system. The urgency of collaborative multi-agent systems results from the fact that the industrial use of fully automated multi-component systems is limited by the financial and infrastructural unavailability of various industries to switch to completely unmanned technologies. The proposed approach combines the latest, but remaining quite recouped, technological advances along with highly skilled human labor. The use of collaborative multi-agent systems will be economically justified in the manufacture of products in small batches, in the conditions of rapid change of product lines, as well as the presence of staff shortages. The article shows that such an approach can significantly reduce automation costs, while ensuring that the specified production indicators are met. This approach allows taking a fresh look at a human, considering him and a robot as equal partners within a collaborative system. The basic concepts and distinctive characteristics of collaborative multi-agent systems are formulated and presented in the work, justifications for their use are given. Creating a new class of collaborative multi-agent systems requires solving a number of problems associated with the interaction of man and robot. The article considers issues related to the work of a person within a collaborative system, with a rational separation of human functions and an automated production system, in accordance with the necessary level of collaboration. The inclusion of a person with his psychoemotional and physical characteristics as an equivalent agent of a multi-agent system causes difficulties in formalizing collaborative multi-agent systems associated with the need to take these features into account and create a sensory-information system. The inclusion of a person with his psychoemotional and physical characteristics as an equivalent agent of a multi-agent system causes difficulties in formalizing collaborative multi-agent systems associated with the need to take these features into account and create a sensory-information system. The paper discusses ways to formalize a collaborative multi-agent system and management approaches.

This paper formulates the tasks that can be solved by the simulation systems of small and medium batch production. The author defines the requirements to the simulation systems of the given production class and describes the strategy and parameters of sampling tests on different stages of an industrial process and, besides, the sequence of experiments execution.

Globally, solar energy has become a major contributor to the rapid adoption of renewable energy. Significant energy savings have resulted from the widespread utilization of solar energy in the industrial, residential, and commercial divisions. This review article comprises research conducted over the past 15 years (2008–2023), utilizing a comprehensive collection of 163 references. Significantly, a considerable focus is directed towards the period from 2020 to 2023, encompassing an extensive investigation into the latest developments in solar panel technology in civil engineering. The article examines the incorporation of solar panels into building designs and addresses installation-related structural considerations. In addition, the present review examines the applications of solar panels in terms of innovative infrastructure development applications of solar panels, such as photovoltaic parking lot canopies and photovoltaic noise barriers, which contribute to improved energy efficiency. It also emphasizes their role in water management systems, including water treatment plants, water pumping and irrigation systems, energy-efficient solar desalination technologies, and promoting sustainable water practices. In addition, this study examines how solar panels have been incorporated into urban planning, including smart cities and public parks, thereby transforming urban landscapes into greener alternatives. This study also examined the use of solar panels in building materials, such as façade systems and solar-powered building envelope solutions, demonstrating their versatility in the construction industry. This review explores the diverse applications of solar energy, which promotes sustainable practices in various industries. Owing to the ongoing research, solar energy holds great promise for a greener and cleaner future.