Joint Control Research Articles

Traceability and policy suggestions for ozone pollution in heavy industrial city in Northeast China.

In the heavy industrial city of Northeast China, there has been a significant decrease in particulate matter pollution while experiencing a sharp increase in ozone (O3) pollution. However, the main influencing factors and source contributions to O3 remain unclear. Taking the case of Siping as an example, this study analyzed the spatiotemporal characteristics, assessed local source contributions to O3, and revealed regional transmission effects using numeric simulation and statistical methods. Temporally, higher O3 concentrations were observed in summer and the afternoon, with hourly peaks up to 254µg/m3. Spatially, O3 pollution was mainly contributed by background concentrations (34.52%), external transport (34.50%), and local emissions (30.98%) during the case study period (June 11-18, 2021). Among the local emission sources, biological emissions, the industrial sector, and the traffic sector accounted for 35.30%, 32.09%, and 23.58% of the O3 concentration, respectively. For regional atmospheric transmission, high O3 pollution was accompanied by wind from the southwest directions, and the trajectory of air mass transport suggests that eastern Mongolia, the Korean Peninsula, and its neighboring regions contribute to O3 pollution. Furthermore, sensitivity analysis showed that O3 pollution in Siping is a co-controlled region by anthropogenic volatile organic compounds (AVOCs) and NOX, which implies control in an optimal ratio of VOCs and NOX emissions. Thus, our results highlight the importance of joint prevention and control of O3 pollution in the region, optimization of biogenic landscape ecology, and control of VOCs and NOx in both the industrial and transport sectors.

Theoretical and numerical analysis of end force of multilayer bellows expansion joint

Multilayer bellows expansion joint is a thin-walled shell widely used in underground pipeline systems for displacement compensation and vibration absorbing. The bellows expansion joint’s end force affects the underground pipeline’s safety. It is urgent to solve the end force of the bellows expansion joint theoretically. However, scholars only obtained the coupling solution of the end force of the bellows expansion joint, which is inconvenient in theoretical analysis and engineering application. This paper proposes a decoupling solution for a bellows expansion joint based on theoretical and numerical methods. The end force is decoupled to the deviation of the bending pressure which is caused by overcoming its own stiffness and internal pressure. In the end force expression, stiffness and internal pressure are independent of each other, which can evaluate the influence of asymmetric pressure difference and external load on end force more accurately. In the end, the accuracy of the decoupling solution is verified by the finite element method and coupling solution. The results show that the decoupling solution agrees with the results obtained by the finite element method and coupling solution. It can provide a theoretical basis for the design of the bellows structure.

Structural assumption on design of rounded rectangular bellows under pressure

Bellows is a flexible component whose volume can be changed by compression or expansion under pressure. Rounded rectangular type bellows is most applied where the internal space of application is strict. The Expansion Joint Manufacturers Association (EJMA) code is world-recognized code for design by formulas method. However, the calculation formulas of stress and deformation in EJMA code does not consider the shape of corner. Therefore, this study proposed a structural assumption of curved beam model to calculate the stress and deformation for rounded rectangular bellows under pressure load by formula calculation method. A parametric study by means of finite element analysis (FEA) was performed to assess the impact of different structural parameters and the applicable scope was investigated. The experimental and numerical results showed that the proposed method can obtain a suitable precision and safe result when ratio of wave height to corner radius is lower than 35 % and the ratio of length of short side length to corner radius is in range 5–20. This study will enrich existing bellows design code and help industry designers to accelerate the optimization iteration in preliminary design stage instead of FEA.

Damage characteristics and mechanical properties of CRTS III track structure in curved sections under longitudinal uneven subgrade settlement

This paper first presents a CRTS III track structure (TS) model specifically designed for curved sections, highlighting its adjustable superelevations feature that enhances adaptability to various high-speed railway curve profiles. The model considers the distribution of steel bars within the TS, concrete damaged plasticity, as well as contact nonlinearity. Afterward, the intricate impacts of longitudinal uneven subgrade settlement (LUSS) position (7 positions), amplitude (5–30 mm), wavelength (5–30 m), and TS superelevation (15–175 mm) on structural damage, stress, deformation, and interlayer gap are studied. The findings reveal that: 1) Under different LUSS positions, the concrete base (CB) experiences the most severe damage, particularly on its thick side. For the TS with 175 mm superelevation, in the wavelength range of 10–20 m, the maximum damage value of CB exceeds 0.9 when LUSS amplitude reaches 20 mm. With the movement of LUSS position, the main damage position of CB changes obviously. When the concrete stress reaches the tensile strength, the steel bars located in adjacent positions progressively assume the primary role in load-bearing. 2) The influence of LUSS on TS deformation and interlayer gap is inevitably associated with the distance between settlement center and expansion joints. Interlayer gaps vary among structural components, which are primarily distributed near settlement center, expansion joints, and settlement edges. 3) As the amplitude increases, both CB and self-compacting concrete layer (SCCL) damage are aggravated. Increasing wavelength initially causes damage to increase, then decrease, and 10–20 m is the most unfavorable wavelength range for most cases. 4) The effect of superelevation on TS damage is complex, varying with structural components and settlement characteristics. In most cases, as superelevation increases, the damage to CB increases, whereas the deformation decreases.

Spatial relevance of synergistic effects between air pollutants and carbon dioxide emission reductions: A case study in the Bohai Rim region of China

Analyzing the spatial correlation of synergistic effect of reducing air pollutants and carbon dioxide (SERAC) between cities, which are spatial hubs characterized by dense populations, industries, and energy usage, provides a foundation for devising regional joint prevention and control policies tailored to local circumstances at this scale. The study analyzed 43 cities in the Bohai Rim region, assessing synergistic emission reduction effects from 2006 to 2020 using a coupled coordination model based on air pollutants (AP) and carbon dioxide (CO2) emission trends. Social network analysis is employed to investigate the structural characteristics and robustness of the spatial correlation network and to unveil the position and significance of each city within the network. The study found that: (1) AP emission equivalent peaked in 2011, while the growth rate of CO2 emission equivalent slowed down in the Bohai Rim region. (2) The low-value areas for the SERAC are spatially clustered in Beijing, Tianjin, and Tangshan, with 90% of the cities in a coordinated state. (3) The network showcasing the spatial correlation between the SERAC features both “local clustering” and “global correlation” coexisting, and its robustness needs improvement. (4) Membership within the plates is relatively stable. On this basis, it is proposed that the Bohai Rim region can enhance the SERAC by establishing a “lead-follow” inter-city mechanism, strengthen the stabilizing role of core entities, implement differentiated emission reduction measures in communities, and expand regional cooperation, ultimately reducing costs and increasing efficiency.

Causes and analysis of position offset of curvilinear continuous beam bridge

This study investigates the problem of beam deflection in curved continuous beam bridges. Taking the D0–D6 spans of the Gongbin Road viaduct as a basis, the main factors influencing the deflection of curved beam bridges are analyzed. The Midas/Civil finite element simulation software is used to calculate and analyze the causes of transverse and longitudinal deflection in curved beam bridges. The results show that the main influencing factor for beam deflection during operation is the system temperature, which causes a displacement greater than the combined displacement caused by self-weight, construction stage, gradient load, vehicle load, and bearing settlement. Damages to expansion joints during operation change the boundary conditions of the beam, preventing longitudinal free expansion under temperature load, and increasing the transverse displacement to 2–3 times the normal working state of the expansion joint, resulting in beam deflection. In the design phase, the selection of curvature radius and fixed support displacement is also a major factor affecting deflection. The smaller the curvature radius, the greater the influence on transverse and longitudinal deflection of the beam. However, when the curvature radius R is greater than 400 m, the impact on beam deflection can be neglected. The closer the fixed support position is to the ends of the bridge, the higher the possibility of bearing detachment, ultimately leading to beam deflection.

Design and control of variable stiffness joint based on magnetic flux adjustment mechanism

Design and control of variable stiffness joint based on magnetic flux adjustment mechanism

Enhancing longitudinal performance in railway suspension bridges through an integrated cable restrainer system

Longitudinal motion is a crucial factor affecting the fatigue life of expansion joints, bearings, dampers and short suspenders in suspension bridges. Traditional control methods relying solely on fluid viscous dampers often magnify the relative displacement between the main cable and the girder (hereafter referred to as relative displacement), leading to fatigue problems in the short suspenders. To overcome these shortcomings, an Integrated Cable Restrainer System is proposed. Firstly, a suspension bridge is described, and both a Refined Finite Element Model (RFEM) and a Simplified Finite Element Model (SFEM) are developed and compared. Subsequently, the effectiveness of three cable measures in reducing the longitudinal motion response and the relative displacement of the bridge is evaluated: the cable central buckle (Type I, connecting the main cable and the girder), the inclined control cable (Type II, controlling the main cable) and the longitudinal control cable (Type III, controlling the girder). Finally, an Integrated Cable Restrainer System integrating type I to type III measures is proposed and compared with FVDs, and its control benefits on train and seismic induced vibration are discussed. The results indicate that the SFEM has a higher calculation efficiency while maintaining comparable accuracy. All three types of cable restrainers are effective in controlling the longitudinal movement of the girder end, although type III increases the relative displacement. The Integrated Cable Restrainer System not only effectively controls longitudinal motion (induced by trains and seismic events) but also reduces the relative displacement at the short suspender positions. By employing the Integrated Cable Restrainer System combined with dampers for controlling longitudinal motion, the undesirable effects associated with damper usage can be effectively mitigated. This research serves as a valuable reference for bridge design and longitudinal motion control in suspension bridges. Data AvailabilitySome or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request.

Parameter Tuning and Positioning Strategy of VD and TMD Joint Control System for Multi-Modal Vibration of Stay Cables

Stay cables are becoming slender and their fundamental frequencies are becoming lower with the span of bridges increasing, thus leading to the occurrence of multi-modal vibration under various excitations. As a simple and effective strategy for cable vibration mitigation, the external damper is widely used in practice. However, one damper normally can target only fewer modes and poses limited effects on the control of multi-modal vibration. This paper proposed the use of a joint control system combining a viscous damper and a tuned mass damper for mitigating the multi-modal vibration of stay cables, followed by the optimization methodology of tuning and positioning. The control performance of the joint system was evaluated by numerical simulations. The feasibility of the joint control system was validated by analyzing the results of the comparative study, therefore providing a possible solution to multi-modal and high-modal vibration of stay cables.

Seasonal quantification of the inter-city transport of PM2.5 in the Yangtze River Delta region of China based on a source-oriented chemical transport model and the Michaelis-Menten equation

Regional transport plays a crucial role in the pollution of fine particulate matter (PM2.5) over the Yangtze River Delta region (YRD). A practical joint regional emission control strategy requires quantitative assessment of the contribution of regional transport. In this study, the contribution of inter-city transport to PM2.5 among the 41 cities in the YRD region were quantitatively estimated using a source-oriented chemical transport model, and then the relationship between the cumulative contribution of regional transport and the distance was examined using the Michaelis-Menten equation. The results show that the Michaelis-Menten equation is suitable to represent the relationship between the cumulative contribution and transport distance. The coefficient of determination (r2) of the fittings is greater than 0.9 in 71 % of the cases in the six subregions and four seasons in YRD. Two key parameters in the Michaelis-Menten eq. K1, indicating the maximum contribution of regional transport, and K2, indicating the distance to which the regional transport contribution reach half the maximum contribution, show substantial regional and seasonal variations. The average K1 is 73.6 %, with lower values observed in the northern part of the YRD and higher values in central Jiangsu. K2 is larger in northern Jiangsu, as well as central and southern Zhejiang. The local contribution in autumn and winter is lower than that in spring and summer in the northern part of the YRD. Particularly in northern Jiangsu, the local contribution reaches 90.4 % in summer but drops to 53.0 % in autumn and winter, illustrating significant impacts of regional transport to PM2.5 in autumn and winter in this area. K2 is larger on polluted days, compared to clean days, indicating greater contributions from regional transport to PM2.5 in YRD. The results can serve as a scientific foundation for implementing regional joint prevention and control measures in the YRD region.

Nonlinear modelling and design of synergetic controllers for single penstock multi-machine hydropower system

The existence of a shared pipeline in a multi-machine system can lead to hydraulic coupling effects between units. It increases the difficulty of controlling hydroelectric units and affects the stability of the power system. This paper refines the model of the hydroelectric generator unit and builds a nonlinear model of a hydro-generator unit with the single penstock multi-machine system. The synergetic control theory was introduced, and the governor and excitation system controllers were designed separately. A joint synergistic controller is obtained by analyzing the two systems' synergistic factors and controlled characteristics. This controller realizes the joint control of the excitation and governor system. The simulation selected a proportion-integral-derivative (PID) controller with optimized parameters, synergistic governor controller (SEC), and synergistic excitation controller (SGC) for comparison to verify the effectiveness of the proposed method. The results indicate that the proposed control method exhibits competent control effects in the single penstock multi-machine system. It can reduce the impact of hydraulic coupling, shorten the adjusting time, and ensure the fast and stable operation of the system. In addition, the values of system time parameters and synergetic control parameters are analyzed separately to provide a reference for achieving optimal control.

Soil-structure interaction issues in integral abutment bridges

Integral Abutment Bridges (IABs) are constructed without expansion joints and bearings, connecting the bridge deck monolithically to the end abutments. Therefore, the construction and maintenance costs of IABs are low compared to conventional bridges with bearings and joints. However, the soil-structure interaction issues are more complex for IABs due to the transfer of deck movements to the foundations through the abutments. Hence abutments of these bridges play an important role in the performance of the substructure and consequently the design approach for the substructure. In this paper, soil-structure interaction issues are investigated for the deck movements due to cyclic thermal loading, which occurs as a combination of daily and seasonal temperature changes. The development of a physical model facility to simulate the problem is described with scaling laws and material properties. The settlement problem at the bridge approach and stress ratcheting phenomena observed at the abutment soil interface are discussed using results from model tests. For the prediction of lateral earth pressure distribution behind abutments, currently available methods are discussed, and modifications are proposed. Finally, the effectiveness of Expanded Polystyrene (EPS) geofoam as an inclusion is discussed to mitigate approach settlement and stress ratcheting problems due to cyclic thermal loading. The results of this study confirm that EPS geofoam is a highly effective material to minimise adverse soil-structure interaction issues in integral bridge abutments.

Simulating the effect of haze management using system dynamics: a case study of Beijing

Haze is a pollution phenomenon that has become increasingly frequent in recent years, primarily composed of SO2, NOx, and particulate matter. Since the “PM2.5 Crisis” in 2013, the Beijing-Tianjin-Hebei region has been plagued by haze. After a series of high-intensity management activities, the air quality in Beijing has continued to improve. To investigate the effectiveness of the haze control measures in Beijing, a dynamic management model was constructed using the system dynamics approach and implemented using Stella software. The model is simulated and evaluated the contribution to different governance strategies (increasing investment in science and technology innovation, reducing motor vehicle ownership, reducing coal consumption, and a combination policy) to reduce haze in Beijing from 2010 to 2025. The validity and robustness of the model were verified through model testing and validation. The simulation results showed that: (1) the combination policy has the most significant effect on reducing energy consumption and pollution emissions, which would reduce energy consumption by 38.93 million tons and pollution emissions by 128.33 thousand tons in 2025, (2) among the single treatment measures, reducing industrial coal consumption is the most effective measure to reducing haze, (3) it is necessary to strengthen the joint prevention and control of the Beijing-Tianjin-Hebei region in the future to promote the sustainable development of the regional environment.

Microstructure and mechanical performance of polyurethane-fly ash composites (PU-FAC) under different effect factors

Conventional bridge expansion joints have the disadvantages of easy damage and lengthy maintenance period. Polyurethane concrete, as a polymer material, is gradually being applied to the repair of expansion joints. However, polyurethane-based repair materials are susceptible to a variety of factors during the early strength-building phase. In this regard, a Polyurethane-Fly Ash Composite (PU-FAC) for rapid repair was proposed in this paper and the effects of different factors on early mechanical performance were investigated. The orthogonal test was first used to determine the optimal mixing ratio of PU-FAC. Then the effects of temperature, catalyst, and curing time on the performance of PU-FAC were investigated by temperature rise curve, maturity index, SEM, and response surface method. The results showed that temperature and catalyst at different curing times had both positive and negative effects on the failure pattern, curing rate, degree of foaming, and mechanical performance. Finally, the optimum values of temperature and catalyst were determined by gray correlation analysis as 15 °C and 0.6 %. By analyzing the effects of different factors on the performance of PU-FAC, it provides a basis for the rapid repair construction of bridge expansion joint anchorage area.

Failure analysis of stainless steel metal hose used for welding

While using ammonia (NH3) gas at 10 bar/500℃, a stainless steel 304 metal hose used as a bellow expansion joint was fractured. It was observed that the fracture of the metal hose started near the weld between the hose and the flange, and progressed to approximately 1/4 of the circumference of the weld.No metallurgical defects were found in the weld where the crack occurred. However, the folded part of the metal hose is welded to the flange, which can cause cracks. In other words, when the metal hose is forcibly compressed or stretched in order to weld it to the flange, the stress concentration due to cold work, including residual stress cause the metal hose to become brittle or crack. It is determined that when a high strain cyclic load or torsional deformation is applied to a high-hardness metal component, the metal hose will reach fatigue failure in a short period of time.

Особенности строительного контроля компонентов и конструкции полимерных зон деформационных швов мостовых сооружений

The article considers the construction control peculiarities of components and design of transition polymer zones of bridge structures expansion joints. The authors have examined the transition zones of expansion joints of in-use bridge structures constructed with polymer concrete. The study revealed the lack of regulatory requirements at the national standardization system documents level. The authors confirmed the possibility of binder composition identification at the organisation of construction control of supplied products in accordance with the requirements of design documentation. The authors also confirmed the possibility of determining the products of chemical reaction during curing of polymer concrete in the transition zone of bridge expansion joints. The authors used a low viscosity liquid epoxy resin based on bisphenol with the inclusion of an amine-type hardener to produce a polymer-concrete mixture. When the components are mixed, a composition is obtained that cures and, when bound to mineral aggregate, provides the product with high strength, water resistance, wear resistance and good adhesion to various substrates. The material obtained for bridge constructions is safe for the environment and does not react with various agents. The method of infrared spectroscopy allows identifying the initial substances and reaction products with the probability of coincidence from 70 to 97%.

FES Control of a Finger MP Joint with a Proxy-Based Super-Twisting Algorithm

To improve motion accuracy through functional electrical stimulation (FES) of forearm muscles, feedback control laws are applied to the index finger’s metacarpophalangeal (MP) joint. This paper introduces a proxy-based super-twisting algorithm (PSTA) for precise servo control of MP joints via FES. The PSTA combines first-order sliding mode control with a second-order super-twisting algorithm, effectively preventing windup during FES saturation and ensuring robust, accurate control. An implicit Euler method minimizes numerical chattering in the digital implementation. Experiments with Arduino and volunteers confirm the algorithm’s effectiveness.

Electrostatic brakes enable individual joint control of underactuated, highly articulated robots

Highly articulated organisms serve as blueprints for incredibly dexterous mechanisms, but building similarly capable robotic counterparts has been hindered by the difficulties of developing electromechanical actuators with both the high strength and compactness of biological muscle. We develop a stackable electrostatic brake that has comparable specific tension and weight to that of muscles and integrate it into a robotic joint. High degree-of-freedom mechanisms composed of such electrostatic brake enabled joints can then employ established control algorithms to achieve hybrid motor-brake actuated dexterous manipulation. Specifically, our joint design enables a ten degree-of-freedom robot equipped with only one motor to manipulate multiple objects simultaneously. We also show that the use of brakes allows a two-fingered robot to perform in-hand re-positioning of an object 45% more quickly and with 53% lower positioning error than without brakes. Relative to fully actuated robots, robots equipped with such electrostatic brakes will have lower weight, volume, and power consumption yet retain the ability to reach arbitrary joint configurations.

Distributed real-time control architecture for electrohydraulic humanoid robots

PurposeThis paper aims to develop an adaptable control architecture for electrohydraulic humanoid robots (HYDROïD) that emulate the functionality of the human nervous system. The developed control architecture overcomes the limitations of classical centralized and decentralized systems by distributing intelligence across controllers.Design/methodology/approachThe proposed solution is a distributed real-time control architecture with robot operating system (ROS). The joint controllers have the intelligence to make decisions, dominate their actuators and publish their state. The real-time capabilities are ensured in the master controller by using a Preempt-RT kernel beside open robot control software middleware to operate the real-time tasks and in the customized joint controllers by free real-time operating systems firmware. Systems can be either centralized, where all components are connected to a central unit or decentralized, where distributed units act as interfaces between the I/Os and the master controller when the master controller is without the ability to make decisions.FindingsThe proposed architecture establishes a versatile and adaptive control framework. It features a centralized hardware topology with a master PC and distributed joint controllers, while the software architecture adapts based on the task. It operates in a distributed manner for precise, force-independent motions and in a decentralized manner for tasks requiring compliance and force control. This design enables the examination of the sensorimotor loop at both low-level joint controllers and the high-level master controller.Originality/valueIt developed a control architecture emulating the functionality of the human nervous system. The experimental validations were performed on the HYDROïD. The results demonstrated 50% advancements in the update rate compared to other humanoids and 30% in the latency of the master processor and the control tasks.

Calculated purpose of the distance between the expansion joints of cement concrete pavements of roads

Problem. The article discusses current issues of increasing the efficiency and quality of construction of cement concrete pavements for highways. It is shown that the regulatory documents in force in Ukraine recommend reducing the distances between compression joints and expansion joints during the construction of roads made of cement concrete. However, such a reduction leads to a slowdown in the pace of road construction and a significant increase in construction costs. The increase in cost occurs due to frequent stoppages of a set of concrete-laying machines and the formation of a large amount of concrete waste. The cost of this waste can reach UAH 200 thousand per 1 kilometer of road. In addition, frequent stops of a set of machines when laying cement concrete pavements of highways slow down the time it takes to put roads into operation. Purpose of the work. The aim is to calculate the expansion of cement concrete pavement when heated under operating conditions. Methodology. The work used formulas for thermophysical calculations during thermal expansion of concrete. The paper presents the results of thermophysical calculations of the expansion of cement concrete pavements of highways during their operation at elevated temperatures. It has been shown that when there are a large number of compression joints, they can partially compensate for the space required for concrete expansion. At the same time, they can act as compression joints during low temperatures. A design of double expansion seams has been proposed, which allows increasing the distance between them. The joint work of compression and expansion seams makes it possible to increase the distance between expansion seams. Due to this, it is possible to reduce their number, while simultaneously increasing the speed of construction and maintaining the quality indicators of the coating concrete. Originality: The article presents the results of a production test of thermophysical calculations. It is shown that two experimental sections of road surfaces were built. The concept of the maximum value of thermal expansion of concrete was further developed. Practical value: On one of them, the distance between expansion joints was 101 m, and on the other – about 300 meters. In this case, the distance between the expansion joints in the double seam was 1.5 meters. These parameters were sufficient for efficient and high-quality operation of double expansion joints.