Abstract: The Sutong Bridge with a span of 1088 m is supported by 272 cables, whose lengths range from 152.85 m to 576.77 m (the longest in the world). The half-year vibration acceleration data of tw...

Abstract: Wide span tractors have a wide transversal bar, on which different implements can be mounted, while the supporting wheels follow the set traffic-lanes. The stability of wide span tractor movement is influenced by unbroken small angular deviations and transversal displacements of the machine due to several factors. These deflections from the set trajectories affect the working implements, especially the peripheral ones, which can cut the plants if wide span tractors are used to manage row crops. In this context, it needs to consider a safeguard zone that allows to reduce the probability of contact between working implements and plants. The aim of this paper was to determine the quantitative effect of transverse displacements of the working implements and the suitable size of the aforesaid safeguard zone. The magnitude of the inner and outer displacements of the working implements depends significantly on their location in relation to the center of the wide span tractor. For working implements located outside the center of the tractor, the outer safeguard zone should be larger than the inner zone. The probability of crop damage by working implements can be reduced by automated control of wide span tractor movement.

Abstract: The morphing aircraft can improve the flight performance of hypersonic vehicles by satisfying the flight requirements of large airspace and large velocity field. In this paper, for the hypersonic variable span missile, the dynamic model and aerodynamic model are established on the variable span characteristic. The adaptive dynamic surface control back-stepping method is used to establish the integrated guidance and control (IGC) with terminal angular constraint in the dive phase of the hypersonic variable span missile. The span variety is used to assist the lift control to achieve fast and stable control for the centroid motion. The simulation results demonstrate that the feasibility and robustness of the IGC method of the hypersonic variable span missile is better than the invariable span.

Abstract: Blade end slots were proposed to control corner separation in a highly loaded compressor cascade in our previous studies. This study focuses on the evaluation of compressor blading with blade end slots and full-span slots. First, the two-dimensional configuration performance is evaluated both for the datum and slotted profiles. The slotted configuration could effectively suppress separation, especially under positive incidence conditions when the separation is large. Thus, two three-dimensional blading with full-span slots and blade end slots (20% span height from the endwall) are compared. Results show that blading with full-span slots could effectively reduce the loss and enlarge pressure rise under relative high incidence angles, while blading with blade end slots could effectively reduce the loss and enlarge pressure rise above an incidence angle of −4 deg. Blading with slots alters the flow structures and reorganizes the flow in the blade end regions. The self-adaptive jets from the slots reenergize the low-momentum flow downstream and restrain its migration toward the mid-span, so that the corner separation is reduced and the performance is enhanced. The loss for the end slotted blade is lower than that of the full-span slotted blade under incidence angles within 4 deg. This is because the additional mixing loss of the jet and the main flow are caused by the full-span slots at the mid-span regions where the flow remains attached for the blade end slots.

Abstract: When designing bridge crossings on highways and railways, classical beam or truss design schemes of structures made of steel or reinforced concrete are usually used, but at present, there is a significant increase in the movement speeds of individual vehicles, axle load and total train weight, and a decrease in temporary intervals between compositions. These factors lead to an increase in dynamic effects and necessitate the use of non-classical design schemes of artificial structures of the transport infrastructure. In the present study, it is proposed to use a three-span arch bridge crossing with a suspension central span structure as the basis for a unified bridge crossing; such an arrangement will allow changing the design length of the central span in a fairly wide range, reduce the total number of supports with an increase in the total length of the bridge crossing, and use such a design as a double-track railway, two- or four-lane road bridge. The calculations and the obtained results of assessing the displacements, internal forces and stresses in the nodes and elements of the proposed bridge crossing design allow us to conclude that the allowable limit magnitudes of the values found are sufficiently uniform load of all the main elements, the absence of pronounced large-scale stress concentrators.

Abstract: Small concrete bridges are important roadway infrastructures in Brazil, where they serve as crucial links in the transportation network. Monitoring and maintenance of these bridges are essential for prolonging their lifetimes. The original work presented in this paper is based on the use of global positioning system (GPS) as a trustworthy tool for characterizing the dynamic behavior of small concrete bridges under normal operating conditions. The proposed inspection procedure includes the analysis of only two GPS signals with a method named the phase residual method, which is based on phase interferometry. Analytical methods, namely, the fast Fourier transform, continuous wavelet transform, and Chebyshev, are effective signal processing techniques for visualizing variations in system frequencies. The object of the study was the bridge over the Jaguari River, which is located in Brazil. The description of the dynamic behavior of the middle span of the concrete bridge was obtained by analyzing data obtained at a sampling frequency of 100 Hz collected for only 1 min. The results provided a clear picture of the energy distribution in the time–frequency plane during forced vibration: (1) the maximum deformation of the main span was pronounced at 3.5–8 mm; (2) the vibration frequency ranged between 4 and 8 Hz; and (3) the values obtained coincided with the values indicated by regular the monitoring sensors, such as accelerometers and transducers of displacements. The advantages of the use of GPS and the contribution to the geotechnical short- or long-term monitoring of road bridges are the use of a reference outside the structure, use under inclement weather conditions, and lack of disruption of traffic.

Abstract: With the increase of the span and height of modern engineering structures, the design length of engineering cables is increasing while the structural form is becoming more complicated, whose dynami...

Abstract: Main cable configurations under final dead load and in the unloaded state and critical construction parameters (e.g. unstrained cable length, unstrained hanger lengths, and pre-offsets for tower saddles and splay saddles) are the core considerations in the design and construction control of a suspension bridge. For the purpose of accurate calculations, it is necessary to take into account the effects of cable strands over the anchor spans, arc-shaped saddle top, and tower top pre-uplift. In this paper, a method for calculating the cable configuration under final dead load over a main span, two side spans, and two anchor spans, coordinates of tangent points, and unstrained cable length are firstly developed using conditions for mechanical equilibrium and geometric relationships. Hanger tensile forces and unstrained hanger lengths are calculated by iteratively solving the equations governing hanger tensile forces and the cable configuration, which gives careful consideration to the effect of hanger weight. Next, equations for calculating the cable configuration in the unloaded state and pre-offsets of saddles are derived from the cable configuration under final dead load and the conditions for unstrained cable length to be conserved. The equations for the main span, two side spans and two anchor spans are then solved simultaneously. In the proposed methods, coupled nonlinear equations are solved by turning them into an unconstrained optimization problem, making the procedure simplified. The feasibility and validity of the proposed methods are demonstrated through a numerical example.

Abstract: A multi-objective optimization approach in order to find the optimal cable overlap length in multi-span cable-stayed bridges with criss-cross cables is presented. The multi-objective optimization is solved by considering three objectives: 1) the cost of the cable system, 2) the displacement at the top of the pylon and 3) the alternate live load on the bridge. An unconventional criss-cross cable system configuration in which cables criss-cross at the center of intermediate spans is used for a bridge with five spans and four pylons. Taking into account both the cable overlap length and the different occurrences of alternate live load, the set of optimal solutions was obtained by the use of genetic algorithms. Results indicate that the optimal cable overlap length corresponds to three criss-crossing cables that corresponds to 0.28 times the length of the central span. Research on multi-span cable-stayed bridges with criss-cross cables allows the analysis of another solution for the problem of stabilizing the displacement of intermediate pylons in this kind of bridge.

Abstract: Experience gained in design, erection and operation of span reinforced concrete structures has proved that practically all of them are subject to complex stress-strain state. At that, the researchers pay considerable greater attention to calculation of strength, deformation analysis and determination of crack resistance in normal cross-sections than to calculation of their support zones, including oblique sections, which results are generally taken into account for determining the section dimensions and the quantity of the cross reinforcement.

Abstract: . The paper presents preliminary findings from a research study designed to assess the health status of a medieval bridge built on 1500 under the Medici dynasty over the river Sieve, close to Florence. The structure, a two span stone bridge with a main central pillar, experienced some restructuring interventions from 1555 to the present. The left span has been closed for some decades, and for many years the water has been allowed to float under it in case of severe flood only. At the beginning of year 2000 the left span has been opened to the regular flux of water. After opening, a maelstrom has been noticed as permanently present at the main pier’s basis highlighting the presence of a fracture in the concrete base around the central pile of the bridge. In order to investigate structural health and to assess bridge’s stability structural inspections and hydraulic surveys have been carried out. This manuscript reports Terrestrial Laser Scanning (TLS) survey results. Surface comparisons to identify anomalies and defromations have been carried out by exploiting Two TLS campaigns that were performed within a 6 years time span.

Abstract: This paper presents modal parameter estimation work on a steel railway bridge at three different temperature conditions using ambient vibration test data. The bridge was built at the end of...

Abstract: Magnetocaloric refrigeration has been pointed out as the most promising alternative to the ubiquitous vapor‐compression refrigeration technology due to its high coefficient of performance. Nevertheless, the use of hydraulic components in current devices is, among other reasons, hindering their commercial widespread. Solid state thermally switchable components are alternatives to the use of fluids. Since current developed structures are not ideal, the refrigerator operation design must be optimized to reduce their strict requirements. Active magnetic regeneration in fully solid state systems has been recently shown to be possible by moving the magnetic field gradually at constant speed, i.e., in several isochronal steps. Here, we investigate the implications of different operating modes on the temperature span, where the motion of the magnetic field includes acceleration and deceleration. When the magnetic field is either applied in a single step or from the cold to the hot reservoirs with linear or decelerated motion and is removed with acceleration motion from the hot to the cold reservoirs, the resulted temperature span increases up to 20%. The implications of each operating mode on the optimum frequency is discussed.

Abstract: This paper analyzes the existing problems in the practical engineering design, resulting from the mechanical properties of two‐way composite concrete slabs with precast ribbed panels (CSPRPs). Due to the influence of the structurally orthotropic characteristic, the calculation formulas for the deflection and bending moments of a CSPRP with three supported edges and one clamped edge under a uniformly distributed load are solved using the load superposition method and the orthotropic plate theory. The CSPRP is calculated as an equivalent isotropic cast‐in‐place two‐way slab using the transformation of function, and the application of the equivalent span ratio. The simplified elastic design method is presented for a CSPRP with three supported edges and one clamped edge under a uniformly distributed load. The elasticity coefficients of the CSPRP with the equivalent span ratio, ranging from 0.5 to 1.0 and stiffness ratios of 0.5 and 2 are obtained using the programming calculation. The linear interpolation method is applied using the equivalent span ratio of an isotropic cast‐in‐place two‐way slab, and one example of a CSPRP with three supported edges and one clamped edge is given to verify. The results show that the simplified elastic design method is accurate and feasible.

Abstract: This paper presents hybrid simulations of a three-span R/C bridge among EU, US, and Canada. The tests involved partners located on both sides of the Atlantic with each one assigned a numeri...

Abstract: Span programs are a model of computation that have been used to design quantum algorithms, mainly in the query model. It is known that for any decision problem, there exists a span program that leads to an algorithm with optimal quantum query complexity, however finding such an algorithm is generally challenging. In this work, we consider new ways of designing quantum algorithms using span programs. We show how any span program that decides a problem f can also be used to decide “property testing” versions of the function f, or more generally, approximate a quantity called the span program witness size, which is some property of the input related to f. For example, using our techniques, the span program for OR, which can be used to design an optimal algorithm for the OR function, can also be used to design optimal algorithms for: threshold functions, in which we want to decide if the Hamming weight of a string is above a threshold, or far below, given the promise that one of these is true; and approximate counting, in which we want to estimate the Hamming weight of the input up to some desired accuracy. We achieve these results by relaxing the requirement that 1-inputs hit some target exactly in the span program, which could potentially make design of span programs significantly easier. In addition, we give an exposition of span program structure, which increases the general understanding of this important model. One implication of this is alternative algorithms for estimating the witness size when the phase gap of a certain unitary can be lower bounded. We show how to lower bound this phase gap in certain cases. As an application, we give the first upper bounds in the adjacency query model on the quantum time complexity of estimating the effective resistance between s and t, R_s,t(G). For this problem we obtain eO(^1_є_(3/2)n√R_(s,t)(G), using O(log n) space. In addition, when μ is a lower bound on λ_2(G), by our phase gap lower bound, we can obtain an upper bound of O(1/є n √R_(s,t)(G)/µ) for estimating effective resistance, also using O(log n) space.

Abstract: Transition zone is one of the vulnerable sections in railway tracks. This study was conducted to assess the effects of using under sleeper pads (USPs) in the transition zone from ordinary ballasted track to railway bridges. For this purpose, a railway bridge with two spans (with the length of 7 m) and an overall length of 15.5 m was selected, followed by designing and conducting field tests in three states: (1) without USP, (2) with USP only on bridge section, and (3) with USP on bridge section and transition zone. The vibrational behavior of the bridge and track components was monitored during train passage by the installation of accelerometers on the bridge, rail, sleeper, and installation of linear variable displacement transducer beneath the bridge deck. The results showed that the maximum effects of using USPs in the transition zone were in the first span so that the average value of accelerations in all speeds decreased in the first span. The acceleration of the rails in the third experiment was 4% lower than the second one and 35% lower than the first one. This reduction for sleepers was 9% and 24%, respectively, and for the bridge deck, it was 48% and 66%, respectively.

Abstract: This study investigated the seismic performance of simply supported girder bridges with a span length of 32 m. Those bridges were a common part in China’s high-speed railway system and used spheric...