Evaluation of the Effect of Saturated Silty and Fine Sand Foundation Improved by Vibro-Flotation in Seismic Area

The improvement of liquefaction foundations in seismic region has been concerning many engineers. The authors had carried out experimental studies on the improvement of saturated silty and fine sand foundations at the suburbs of Beijing by vibroflotation method. The test results are described and the improvement effects are evaluated in this paper

Capacity of Remote Classification Over Wireless Channels

Wireless connectivity creates a computing paradigm that merges communication and inference. A basic operation in this paradigm is the one where a device offloads classification tasks to the edge servers. We term this remote classification, with a potential to enable intelligent applications. Remote classification is challenged by the finite and variable data rate of the wireless channel, which affects the capability to transfer high-dimensional features and thus limits the classification resolution. We introduce a set of metrics under the name of classification capacity that are defined as the maximum number of classes that can be discerned over a given communication channel while meeting a target classification error probability. The objective is to choose a subset of classes from a library that offers satisfactory performance over a given channel. We treat two cases of subset selection. First, a device can select the subset by pruning the class library until arriving at a subset that meets the targeted error probability while maximizing the classification capacity. Adopting a subspace data model, we prove the equivalence of classification capacity maximization to Grassmannian packing. The results show that the classification capacity grows exponentially with the instantaneous communication rate, and super-exponentially with the dimensions of each data cluster. This also holds for ergodic and outage capacities with fading if the instantaneous rate is replaced with an average rate and a fixed rate, respectively. In the second case, a device has a preference of class subset for every communication rate, which is modeled as an instance of uniformly sampling the library. Without class selection, the classification capacity and its ergodic and outage counterparts are proved to scale linearly with their corresponding communication rates instead of the exponential growth in the last case.Comment: Submitted to IEEE for possible publicatio

Effect of wing flexibility on aircraft flight dynamics

The purpose of this thesis is to give a preliminary investigation into the effect of wing deformation on flight dynamics. The candidate vehicle is FW-11 which is a flying wing configuration aircraft with high altitude and long endurance characteristics. The aeroelastic effect may be significant for this type of configuration. Two cases, the effect of flexible wing on lift distribution and on roll effectiveness during the cruise condition with different inertial parameters are investigated. For the first case, as the wing bending and twisting depend on the interaction between the wing structural deflections and the aerodynamic loads, the equilibrium condition should be calculated. In order to get that condition, mass, structure characteristics and aerodynamic characteristics are estimated first. Then load model and aerodynamic model are built. Next the interaction calculation program is applied and the equilibrium condition of the aircraft is calculated. After that, effect of wing flexibility on lift parameters is investigated. The influence of CG, location of lift and location of flexural axis are investigated. The other case is to calculate the transient roll rate response and estimate the rolling effectiveness of flexible aircraft, and compared with the rigid aircraft’s. A pure roll model is built and derivatives both for the rigid wing and the flexible wing are estimated. It has been found that flexible wing leads to the loss of control effectiveness, even cause reversal when reduces the structure natural frequency. The influence of inertia data for flexible roll is also investigated

Measurement of Interfacial Characteristics of Horizontal and Inclined Oil–Water Flows by Using Wire-Mesh Sensor

Oil–water flows are widely encountered in petroleum, chemical, nuclear reactors, and other crucial industrial processes. Due to gravity and interaction between phases, horizontal and inclined oil–water two-phase flows are characterized by remarkable multi-scale structure characteristics, such as large-scale stratified interface and small-scale droplets entrainment. Moreover, a slight change in the pipe inclination will lead to significant changes in the local oil–water flow structures, which results in great challenges in the measurement of the interface structures. In this study, we design a 10 × 10 conductance wire-mesh sensor (WMS) to detect the interfacial characteristics of horizontal and inclined oil–water flows. Firstly, we carry out horizontal and inclined oil–water flow experiments. The influence of pipe inclinations on the flow transition boundary is analyzed. The three-dimensional (3D) structures of oil–water flows are visualized based on the WMS measurement response. Then, edge detection is implemented to process the two-dimensional (2D) flow images visualized by the WMS. The influence of complexly distributed droplets is effectively removed by using binary image morphological transformation and watershed algorithm, and thus, oil–water interface structures are accurately extracted. Finally, the influence of the oil–water flow conditions and pipe inclinations on the configuration, height, and length of the stratified interface are investigated

Structural and electronic properties of medium-sized beryllium doped magnesium BeMgn clusters and their anions

Bimetallic clusters have attracted much attention because of the structural and property changes that occur: cluster size and doping. Here, we performed a structural search of the global minimum for bimetallic BeMgn0/− (n = 10–20) clusters by utilizing efficient CALYPSO structural searching program with subsequent DFT calculations. A large number of low energetic isomers converge and the most stable structures are confirmed by comparing the total energies for different cluster sizes. Satisfactory agreement between theoretical and experimental PES spectra demonstrates the validity of our predicted global minimum structures. It is found that the most stable structures of BeMgn0/− clusters are filled cage-like frameworks at n = 10–20. The localized position of Be atoms changes from completely encapsulated sites to surface sites, after which the position reverts to the caged Mg motif. In all BeMgn0/− clusters, the charge transfers from the Mgn motif to Be atoms. Increasing occupations of p orbitals manifest their increasing metallic behaviors. A stability analysis revealed that the D4d symmetric BeMg16 caged structure with one centred Be atom has robust stability, which can be because BeMg16 possesses a closed electronic shell of 1S21P61D101F42S21F10 filled with 34 valence electrons and strong Be-Mg bonds due to s-p hybridization. This finding is supported by multi-centre bonds and Mayer bond order analyses

Surfactant-Assisted Synthesis of Micro/Nano-Structured LiFePO4 Electrode Materials with Improved Electrochemical Performance

As an electrode material, LiFePO4 has been extensively studied in the field of energy conversion and storage due to its inexpensive cost and excellent safety, as well as good cycling stability. However, it remains a challenge to obtain LiFePO4 electrode materials with acceptable discharge capacity at low temperature. Here, micro/nano-structured LiFePO4 electrode materials with grape-like morphology were fabricated via a facile solvothermal approach using ethanol and OA as the co-solvent, the surfactant as well as the carbon source. The structure and electrochemical properties of the LiFePO4 material were investigated with x-ray diffraction (XRD), field emission scanning electron microscopy (SEM), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS), and the formation mechanism of the self-assembled micro/nano-structured LiFePO4 was discussed as well. The micro/nano-structured LiFePO4 electrode materials exhibited a high discharge capacity (142 mAh·g−1) at a low temperature of 0 °C, and retained 102 mAh·g−1 when the temperature was decreased to −20 °C. This investigation can provide a reference for the design of micro/nano-structured electrode materials with improvement of the electrochemical performance at low temperature