Additional Moment Research Articles

Research on Decoupled Optimal Control of Straight-Line Driving Stability of Electric Vehicles Driven by Four-Wheel Hub Motors

The optimal control strategy for the decoupling of drive torque is proposed for the problems of runaway and driving stability in straight-line driving of electric vehicles driven by four-wheel hub motors. The strategy uses a hierarchical control logic, with the upper control logic layer being responsible for additional transverse moment calculation and driving anti-slip control; the middle control logic layer is responsible for the spatial motion decoupling for the underlying coordinated distribution of the four-wheel drive torque, on the basis of which the drive anti-skid control of a wheel motor-driven electric vehicle that takes into account the transverse motion of the whole vehicle is realized; the lower control logic layer is responsible for the optimal distribution of the driving torque of the vehicle speed following control. Based on the vehicle dynamics software Carsim2019.0 and MATLAB/Simulink, a simulation model of a four-wheel hub motor-driven electric vehicle control system was built and simulated under typical operating conditions such as high coefficient of adhesion, low coefficient of adhesion and opposing road surfaces. The research shows that the wheel motor drive has the ability to control the stability of the whole vehicle with large intensity that the conventional half-axle drive does not have. Using the proposed joint decoupling control of the transverse pendulum motion and slip rate as well as the optimal distribution of the drive force with speed following, the transverse pendulum angular speed and slip rate can be effectively controlled with the premise of ensuring the vehicle speed, thus greatly improving the straight-line driving stability of the vehicle.

Numerical study on fire resistance of rectangular section stainless steel-concrete composite beam

To investigate the fire resistance of stainless steel-concrete composite beams (referred to as stainless steel composite beam), numerical simulations of rectangular section stainless steel composite beams under fire were carried out. The influences of load ratio, thickness of concrete slab, width of concrete slab, reinforcement ratio of concrete slab, height of stainless steel beam, width of stainless steel beam and span of composite beam on the fire resistance of rectangular section stainless steel composite beams were analyzed. Due to the large coefficient of thermal expansion of stainless steel material, the expansion of stainless steel beam will produce an additional bending moment in the stainless steel composite beam under fire, which has a great influence on the fire resistance of stainless steel composite beams. Finally, a simplified calculation method of temperature field distribution of rectangular section stainless steel composite beam was proposed. To adjust and enlarge the maximum bending moment at the mid-span of stainless steel composite beam, the coefficient of temperature additional bending moment was introduced into the calculation formula of critical temperature of stainless steel composite beams, which effectively improves the accuracy of the fire-resistant design method for stainless steel composite beams.

Design of PID controller and fan wing controller for FanWing

FanWing, a concept for embedding a cross-flow fan into a thick wing for lift enhancement and thrust production, is a new kind of aircraft. Since the action position of the fan wing is after the center of gravity, the rotation of the cross-flow fan produces lift, thrust, and an additional pitch-down moment. Although FanWing has achieved great success at the air shows, scientists mainly concentrate on optimizing the fan wing structure to improve the characteristics of the power system and the dynamic performance of FanWing but rarely consider the control system. There is still a lot of work to do on theoretical research and engineering applications. Thus, the present paper will do some research on the control systems, including two control methods: the traditional elevator, aileron, and rudder control method and the fan wing control method. The influence of the additional pitch-down moment is researched. Based on the study of a 3.5 kg FanWing, the proportional integral differential (PID) controllers are designed. The proposed fan wing controller has been compared with the traditional PID one. The simulations show the effectiveness of the proposed fan wing controller in terms of the nonlinear simulation.

Numerical Simulation of Pile Settlement under Large Diameter Submarine Shield Tunnel

In view of the domestic first large diameter shield close Marine environment down wear large bridge project, Shenzhen high-speed along the river shield tunnel under wear before the Shenzhen Sea bridge as the background, the numerical simulation method, in view of the large diameter submarine shield under the bridge pile foundation, through different ways and methods on influence of settlement of pile foundation. The calculation results show that the additional bending moment of the bridge pile is small, the maximum settlement of the bridge pile is within the range of the control standard value, and the maximum horizontal displacement of the bridge pile is within the range of the control standard value, so the bridge will not be damaged. It can be seen that the construction of submarine shield tunnel has a certain degree of influence on the cross-sea bridge, but after applying engineering measures, the impact on the bridge can be effectively reduced to ensure the safety of high-speed railway bridge. The research results can provide reference for the construction design of the type of engineering.

Mechanical design and analysis of a novel variable stiffness actuator with symmetrical pivot adjustment

The safety of human-robot interaction is an essential requirement for designing collaborative robotics. Thus, this paper aims to design a novel variable stiffness actuator (VSA) that can provide safer physical human-robot interaction for collaborative robotics. VSA follows the idea of modular design, mainly including a variable stiffness module and a drive module. The variable stiffness module transmits the motion from the drive module in a roundabout manner, making the modularization of VSA possible. As the key component of the variable stiffness module, a stiffness adjustment mechanism with a symmetrical structure is applied to change the positions of a pair of pivots in two levers linearly and simultaneously, which can eliminate the additional bending moment caused by the asymmetric structure. The design of the double-deck grooves in the lever allows the pivot to move freely in the groove, avoiding the geometric constraint between the parts. Consequently, the VSA stiffness can change from zero to infinity as the pivot moves from one end of the groove to the other. To facilitate building a manipulator in the future, an expandable electrical system with a distributed structure is also proposed. Stiffness calibration and control experiments are performed to evaluate the physical performance of the designed VSA. Experiment results show that the VSA stiffness is close to the theoretical design stiffness. Furthermore, the VSA with a proportional-derivative feedback plus feedforward controller exhibits a fast response for stiffness regulation and a good performance for position tracking.

Influence of earthquake vertical excitations on Sloshing-Created P-Δ effect in elevated water Tanks: Experimental Validation, numerical simulation and proposing a modification for Housner model

Seismic sloshing in elevated water tanks creates some additional base moment, which simultaneous with the effect of strong vertical acceleration of near-source earthquakes may increase the P-Δ effect, as an important factor in seismic design of these structures. This study was performed to investigate the extent of this combined effect. First, an experiment was conducted to provide a set of results for validating the finite element analysis (FEA) modeling, conducted as the second part of the study. The test tank was cylindrical with a diameter of 60 cm, installed on an innovative simple shaking table, capable of creating simultaneous horizontal and vertical harmonic excitations. Different frequencies and water depths were used in the tests. For verification, the maximum sloshing height was measured and compared with FEA results. The verified FEA process was used to simulate elevated tanks of actual sizes for various water height to tank diameter and also tank height to tank diameter ratios, using three-component accelerograms of seven selected earthquakes, mostly having strong vertical components, creating totally 126 dynamic FEA cases. In the last stage, a modification was done on the Housner spring-mass model for using it in 3D state with consideration of vertical excitations. Numerical results indicate that the sloshing height and the base moment could increase in average about 20% and 10%, respectively, due to the effect of earthquake vertical excitations. Also, comparison of FEA results with those obtained by using the proposed 3D modified Housner model shows a good agreement of around 90% on average.

Integrated robust dynamics control of all-wheel-independently-actuated unmanned ground vehicle in diagonal steering

In the future civilian Intelligent Transportation System (ITS) and military area, the Unmanned Ground Vehicles (UGVs) are supposed to replace humans to conduct various tasks in wide civilian or military applications. This paper aims at improving the overall performance of the All-wheel-independently-actuated (AWIA) UGV. Each wheel of the AWIA UGV is independently driven and steered by the motors with independent active suspension equipped to achieve the great potential of mobility, maneuverability, and controllability. Aiming to improve the performance of AWIA UGV in diagonal steering mode under critical circumstances, a novel integrated control approach is extended in this paper based on robust H2/H∞ theory. The major control objective is to generate additional vehicle active moment by full X-by-wire technique to collaboratively control lateral and roll motion of the vehicle to maintain a target diagonal steering performance. A wheel force distribution controller in the control executive layer interfaced to actuators is applied to achieve the resultant active control moment at each wheel corner, by controlling each independent drive motor, independent steer motor, and active suspension actuator. The effectiveness of the proposed control approach is validated by an AWIA UGV testbed by performing the step-steer experiments.

The role of institutions in private investment: panel data evidence

PurposeThis study aims to examine the effects of institutions on private investment (PI) using panel data analysis, where the sample countries consist of 100 countries around the world and the time period is covering from 2007 to 2016. The system generalized method of moments (GMM) estimator, introduced by Arellano and Bond (1991) and further developed by Blundell and Bond (1998) is used to analyze the data sets.Design/methodology/approachThis study uses the panel data approach to estimate the empirical model due to the panel nature of the data. In particular, due to the presence of lagged dependent variables and the ability to capture individual country-specific effects, the system GMM estimator, introduced by Arellano and Bond (1991) and further developed by Blundell and Bond (1998), is adopted to analyze the roles of institutions in PI. The system GMM is developed specifically to solve the problems of weak instruments and persistency (Blundell and Bond, 1998). Jointly, they suggest to adopt additional moment conditions where lagged difference of the dependent variable is orthogonal to the level form of the disturbances. The system GMM estimator is able to combine the moment conditions for the different models, as well as the level model, thereby (is capable of) generate consistent and efficient parameters. Due to the dynamic nature of the data, this study uses one-step and two-step system GMM to investigate the roles of institutions in PI.FindingsThe empirical results based on the two-step system GMM demonstrate that the quality of institutions plays an important role in stimulating PI. The finding is reinforced by the analysis of the institutional sub-components’ effects on PI.Originality/valueThis study is unique as its measurement of institutions is multi-dimensional (including law and order, rules and regulation, government stability, bureaucratic quality, control of corruption, socio-economic condition, etc.), and hence are more comprehensive. Second, it is different than the previous studies as its sample of countries includes both democracies and non-democracies, as well as both developed and non-developed economies in which policy implications are widely acceptable. Third, this study contributes to the policymakers especially those in the debt-ridden economies where governments are budget-tightening (limited capacity for public investment), as to which practical direction should be focused on so as to attract PI and eventually sustainable growth can take place.

Dynamic Modeling and Nonlinear Characteristics of a Cracked Bolt-Disk Combined Rotor System

Abstract Different from the crack on the rotating shaft, the crack on the bolt, which is a connecting part of the bolt-disk combined rotor, is a kind of local defect. The local crack on the bolt under high pretension is always in open state, and it increases the overall vibration of the combined rotor significantly in practice. This paper studies the modeling of the crack on the bolt and nonlinear dynamic behaviors of the cracked bolt-disk rotor system. The circumferential bolts with a transverse open crack are treated as several bar elements under the assumption that each bolt has the same original tensile extension length. The cracked correction coefficient is introduced to describe the decreasing amount of bolt's tension due to crack. After this coefficient is obtained according to finite element method, the stiffness matrix of circumferential bolts with crack is built based on total potential energy. The dynamic model consists of a time-independent stiffness matrix for perfect bolts, a time-variant reductive stiffness, and an additional moment. As a result, the crack in bolt reduces rotor's nonlinear stability and leads to greater vibration and fluctuation. In addition, crack depth has much larger influence than crack location on the dynamic behaviors.

Anti-collapse performance of composite frame with special-shaped MCFST columns

A spatial steel frame with concrete slab and special-shaped multi-partition concrete filled steel tubular columns was tested in a simulated scenario of progressive collapse. The load-deformation relationship of the frame with damaged middle column under vertical load is discussed. Parametric analysis is also conducted by using a validated FE model. The results show that the failure of the specimen resulted from the fracture of the bottom beam flange eventually. The configuration of side plate connection and multi-partition concrete filled steel tubular column both could provide a reliable load-redistribution path for additional loads due to single column loss. The designed frame exerts good robustness to resist the collapse resulting from middle column loss. The simulation shows that single-column removal would cause additional lateral force and moment on the adjacent columns, besides axial force. The length of side plate exhibits more influence on the performance of the frame than the thickness of side plate.

Behaviour and failure modes of steel parking structure column under transverse impact

The columns of steel parking structures are prone to collision while parking vehicles. The current design codes offer limited guidance for designing built-in columns with sufficient impact resistance to transverse impacts. In this study, we performed a series of numerical studies to comprehensively understand the behaviour and failure modes of the impacted column. First, a simplified analysis method was proposed to simplify the overall structural model. The simplified analysis models (SAMs) and overall analysis models (OAMs) were compared, and the results demonstrated that the proposed method can reasonably predict the behaviour of the impacted column. The behaviour of the column was estimated under common loading conditions, and the effects of the impact velocity, axial loading, and impact height were studied. Furthermore, two structural configurations, SAM-1 and SAM-2, were compared and evaluated. SAM-2 had better impact resistance than SAM-1 owing to the presence of a back beam, which reduced the effect of the additional moment due to deformation, thereby decreasing the external work and total input energy. The failure modes were classified into three categories considering different impact velocities, axial loads, and impact heights. The robustness of the structure under impact can be improved by designing a reasonable axial loading level for the column to avoid failure mode 3.

Coordinated control of distributed drive electric vehicle by TVC and ESC based on function allocation

Safe and comfortable driving experience includes the improvement of handling performance and stability control. This paper proposed a coordinated controller based on the function allocation for the handling performance and stability of distributed drive electric vehicles. The proposed controller has three layers. The upper control layer designs a dynamic stability envelope boundary suitable for various driving conditions through the phase plane method, and on this basis, the function allocation rules of torque vector control (TVC) strategy and electronic stability control (ESC) strategy were formulated. The medium control layer used the robust [Formula: see text] dynamic output feedback control method and the improved particle swarm optimization (PSO) parameter self-adjusting method to calculate the additional yaw moment required by the TVC strategy and the ESC strategy, respectively. The two types of additional yaw moment are implemented by the in-wheel motor and the hydraulic brake mechanism respectively. The lower control layer optimized the four-wheel torque and braking force based on the optimal tire load rate using the quadratic programming method. The proposed coordinated controller was performed in the CarSim/Simulink co-simulation platform and tested in a real vehicle platform. The results show that the proposed controller can improve the vehicle dynamic response according to the driver’s intention, thus bringing the better handling performance and stability.

Structural Optimization of Anti-Interference of Small Ducted Aircraft

The small ducted type aircraft has small volume and light weight, and the ducted body occupies a large proportion in the pneumatic surface of the whole machine. The presence of the ducted causes the aircraft to produce momentum resistance and additional resistance moments under the side wind/gust interference. The effect is to produce the rise torque that causes the aircraft to “rise up”, which makes the aircraft more susceptible to side wind/gust interference and deviates from the stable equilibrium state. Therefore, compared with the open rotor unmanned aerial vehicle(UAV), the small ducted aircraft itself has worse anti-interference ability. The above analysis shows that the ring structure of the culvert makes the aircraft itself more vulnerable to the side wind/gust interference in the environment and forms an additional resistance moment. Therefore, how to improve the inherent anti-jamming capability of the small ducted aircraft through structural optimization is the problem to be solved in this paper.

A novel precast concrete beam-to-column connection with replaceable energy-dissipation connector: Experimental investigation and theoretical analysis

To avoid the damage of the connection due to the overstrength of beam strength, and the alternation of the strength hierarchy in the structural system, a novel precast concrete beam-to-column connection is proposed herein. In the proposed connection, a novel replaceable energy-dissipation connector (REDC) was placed at the bottom of a hidden corbel. In addition, a narrow vertical slot was placed adjacent to the hidden corbel to reduce the beam overstrength. First, the structural features and mechanical mechanism of the proposed novel precast connection were discussed. Second, three low-cycle quasi-static loading tests were carried out on a single full-scaled specimen by using three REDCs of different sizes. The test results showed that the seismic performance of this novel precast connection was excellent and that the additional bending moment caused by beam overstrength in the novel precast connection was significantly lower than that of a conventional connection. Third, three finite element models were developed to further analyze how to reduce the additional bending moment and to always keep the top reinforcements in the elastic range. Finally, relevant design suggestions were provided. The additional bending moment of the novel precast connection designed according to the proposed formulas can be minimized. In view of this, the bending moments of the novel connection can be regarded as a controllable variable.

Design model for bolted angle members in compression including joint stiffness

Knowledge of type and size of rotational restraints at the member's ends (provided by the adjacent structure) is crucial for the prediction of the compression member capacity of bolted angles. This was highlighted by means of experimental and numerical investigations in the past. Due to the eccentric connection on only one angle leg, additional bending moments are acting on the member, leading to a complex load carrying behaviour with flexural and/or lateral torsional buckling phenomena.Detailed analytical models for the estimation of appropriate spring stiffness values have been developed for several practical applications in buildings with two-bolt connections at both member's ends. The investigated connection details comprise a simply fixed gusset plate (e.g. as attachment to concrete walls), a joint to the flange of an I-shaped section and a joint to the web of an I-shaped section via a gusset plate. Based on that, a design model was developed for bolted angle members with rotational spring restraints at the member's ends and an eccentric compression loading N, in order to calculate the compression capacity NR. The thereby determined resistances NR,model are compared with the results of sophisticated 3D nonlinear finite element calculations NR,FE that consider the detailed joint configuration and the eccentric load introduction as well as equivalent geometric imperfections. It is shown that the resistances based on the proposed design procedure are slightly conservative compared to the real behaviour of the angle member. In addition, the large increase in capacity (compared to the simply supported reference case) is highlighted.

Investigating the behaviour of steel framed-tube and moment-resisting frame systems exposed to fire

This paper investigates the behaviour of two popular structural systems subjected to overheating and column removal cases, which may follow fire incidents. A typical 15–storey steel building is designed with two types of structural system framed-tube and moment-resisting frame. The nonlinear behaviour of these structures under different fire scenarios is investigated using OpenSees Software. The results indicate that deflection of heated beams is insignificant below 400 °C but after that, degrading mechanical properties of steel material leads to large deflection and runaway of heated beams at temperatures below 600 °C. Also, heating the beams of structures initially induces large axial forces in the beams due to restraints on thermal expansion. Thermal expansion of heated floors induces large horizontal displacement and consequently causes additional bending moments in the exterior column. So columns reach their elastic limit at the early stages of fire. Columns of the framed-tube system reach their elastic limit at lower temperatures (130 °C) but fail at higher temperatures (380 °C) compared to columns of the moment-resisting frame system (210 °C). In addition, the lower storey and interior columns are more vulnerable to progressive collapse and fail at lower temperatures (330 °C) due to carrying more gravity loads. In most fire scenarios, beams and columns of framed-tube systems fail at higher temperatures and perform well in the fire than moment-resisting frame systems. In column removal scenarios, mid-span displacement of the heated beam increases significantly, leading to downward movement of upper stories. Also, column removal in the framed-tube system is more destructive than in the moment-resisting frame system. In general, in both structural systems, column removal scenarios, which may follow fire, induce more damage to the structures than general temperature rise in considered fire scenarios.

A novel path tracking approach considering safety of the intended functionality for autonomous vehicles

To reduce the adverse effect of the functional insufficiency of the steering system on the accuracy of path tracking, a path tracking approach considering safety of the intended functionality is proposed by coordinating automatic steering and differential braking in this paper. The proposed method adopts a hierarchical architecture consisting of a coordinated control layer and an execution control layer. In coordinated control layer, an extension controller considering functional insufficiency of the steering system, tire force characteristics and vehicle driving stability is proposed to determine the weight coefficients of automatic steering and the differential braking, and a model predictive controller is designed to calculate the desired front wheel angle and additional yaw moment. In execution control layer, a H∞ steering angle controller considering external disturbances and parameter uncertainty is designed to track desired front wheel angle, and a braking force distribution module is used to determine the wheel cylinder pressure of the controlled wheels. Both simulation and experiment results show that the proposed method can overcome the functional insufficiency of the steering system and improve the accuracy of path tracking while maintaining the stability of the autonomous vehicle.

Analysis of magnetic properties of A3B6 type of semiconductor crystals with metalic impurities due to their military applications

The Earth's magnetic field is affected by the presence of heavy military armored vehicles which creates an additional magnetic moment. This distortion of the magnetic field, can be detected using magnetoresistive structures. This article touches base on the possibility of using semiconductor material such as InSe for high precision measurement of the magnetic field. The properties of InSe structures with regard to electrical, magnetic and optical characteristics are discussed. The effect of sharp anisotropy of InSe layered structure which consists in the strong covalent bond within the layers and a weak van-der-Waals bond in the interlayer space is discussed with regard to the explanation of how electrical, magnetic and optical properties are altered. The peculiarity of the spatial orientation of the material with regard to the direction of the magnetic field is considered. The impact of intercalation of InSe, GaSe by various concentrations of metal impurities such as nickel and other elements of 3d iron group is studied. Bode diagrams for pure InSe system are compared with the ones of NixInSe (for various x values). Also the effect of different temperatures ranging from room temperature to liquid nitrogen on the pattern of Bode diagrams is analyzed. The extent of how the magnetic properties of semiconductor crystals of the A3B6 type are altered by the presence of the metal impurities and their concentration is analyzed. Theoretic background for this paper is based on a well-known statement that layer structures such InSe or other A3B6 structures can be viewed as quasi two-dimensional. So, layers with strong covalent bond are formed by In-Se atoms, whereas interlayer space is filled with a weak Van der Waals bond. Within this model the processes across the layers can be described as a perturbation to the ones along the layers. This causes a strong anisotropy of the properties of these structures. Military implication of InSe structures mentioned throughout this paper is that these structures possess magnetoresistive properties and they were proved to be useful for the components of the magnetic sensors of civil and military use. This paper also touches base on how the InSe semiconductor crystals intercalated by 3d-elements can extend the functionality of magnetic sensors designed for heavy armor detection.

Enhancing #TdF2017: Cross-media controversies and forensic fandom during live sports events

This article considers the cross-media dynamics related to controversies surrounding the Tour de France 2017. It posits sports controversies are prime cases for studying how mainstream media and online platforms impact each other. Based on a large data set of tweets and combining a digital methods approach with a close reading of tweets, we show how the often discussed potential of sports’ live events to synchronize different media becomes intensified in case of controversies, which trigger an influx of users and spawn additional moments of shared attention. Additionally, controversies in sports incite visual activities of fans using and augmenting material from different sources to support their take on the issue. We suggest to understand this as an example of ‘forensic fandom’ and show how it entangles different temporal and visual affordances: the liveness of television, the ad hoc publics of Twitter and the archival function of YouTube. Adding to prior cross-media and cross-platform research, we argue that media (including their seemingly specific temporal and visual qualities) are always dependent on and shaped by particular cultural practices, topics and events that trigger connections between different media and platforms.

Limit states design of crane runway girders

Steel crane runway girders are subjected to torsion by their eccentric loads. The twist rotation of the principal axes caused by torsion induces additional bending moments, and reduces the resistance to lateral-torsional buckling. There is little guidance on how to design for torsion, and design procedures are often intuitive, with varying degrees of rationality and precision.This paper seeks to establish a logical procedure for designing crane runway girders which is based on an extension of the limit states methods of designing for biaxial bending. An additional term for the ratio of the design torque to the section torsion resistance is included in the interaction equations. Proposals are made for determining this section resistance. Research has shown that this addition can allow for the reduction in the lateral-torsional buckling resistance caused by the twist rotations. A linear elastic analysis of the twist rotations is used to determine the moment increases caused by torsion.An example of the proposed method is developed and illustrated by a design example. The design is governed by the member capacity, which is mostly affected by the lateral-torsional buckling capacity. Torsion has a very small effect, and the twist rotations are small. The twist rotations cause a significant increase in the minor axis bending moment, but this has only a minor effect on the member capacity.