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We design a new class of bifunctional materials, namely, BaMX4 (M = Co, Ni, Fe, Mn; X = F, Cl, Br, I), with corner-shared octahedral layered perovskite structures. Our joint experimental and theoretical study demonstrates that BaCoF4, a prototype in this new class, possesses a unique combination of multiferroic and photovoltaic properties. Moreover, BaCoF4 exhibits both an antiferromagnetic spin structure and ferroelectric polarization along the (001) direction. These combined electronic and optical features render BaCoF4 a promising bifunctional material for application in spintronic or photovoltaic devices. Density functional theory calculations suggest that the dominant point defects in BaCoF4 are mostly shallow-level donor defects, leading to fascinating n-type self-doping. As such, a BaCoF4 layer may be exploited for electron transport and light absorption altogether, which may enhance the photovoltaic performance in solar cells. To confirm this predicted feature, we incorporate BaCoF4 as an electron...

Double-layered V2O5 and its analogues have received increasing attention as a proper cathode for Mg2+, Na+, Li+ ion batteries, even for ammonium ion batteries. Our theoretical research focuses on the effects of NH4+ ions on the structural stability and the ion diffusion properties of double-layered V2O5. The elastic constant calculations indicate the NH4+ and water contents have a dramatic influence on the stability of the electrode. When the ratio of H2O and ammonia ions decreases to (NH4)0.125V2O5·0.125H2O, double-layered bronze will transform into other phases. The predicted specific capacity for the redox process from (NH4)0.5V2O5·0.5H2O to (NH4)0.125V2O5·0.125H2O is 54.6 mA h g-1, which agrees with the experimental value of 55.6 mA h g-1. From the diffusion barrier calculations, it is found that the H2O molecules can shield the polarization of NH4+ and lower the diffusion barrier of NH4+ ions. Furthermore, the migrations of common charge carriers in NH4+ pre-intercalated V2O5 have also been studied, which implies that Li+, Zn2+, Na+, Mg2+ ions may move easily in the electrode with energy barriers lower than 525 meV. Our findings match well with the reported experimental results. A special structure of Mg6NH4V8O20 with a much higher Mg ion concentration has been reported. Our findings show that the theoretical specific density of Mg batteries based on NH4+ pre-intercalated V2O5 can be improved to 431 mA h g-1, which is 2.5 times larger than the reported values. This work highlights the effects of the ratio of NH4+ and H2O on double-layered V2O5 and provides insights into designing vanadium oxide based fast-diffusion multivalent ion conductors, which are suitable for battery applications.

Functionalized graphene is widely used in various functional devices. Here, we introduce a simple plane capacity model and the density functional theory to investigate the origin of charge transfer in the graphene/CH3NH3PbI3 interface, where graphene can be p-type or n-type doped by combining with different exposed surfaces of CH3NH3PbI3. Our calculations indicate that at the equilibrium distance, the work function of isolated graphene layer should be corrected by adding a value for assessing the charge transfer. After integrating the perovskite film with the functionalized graphene layer, we obtain a van der Waals heterostructure solar cell with a p–i–n configuration, which introduces a built-in electrical field to facilitate the separation and transport of the photogenerated carriers. The new p–i–n junction highlights the interface effect on graphene in solar cell, which offers an avenue to design new photovoltaic devices with high performance.

Fundamental understanding of interfacial charge behaviors is of great significance for the optoelectronic and photovoltaic applications. However, the crucial roles of perovskite terminations in charge transport processes have not been completely clear. We investigate the charge transfer behaviors of the CsPbI3/black phosphorus (BP) van der Waals heterostructure by using the density functional theory calculations with a self-energy correction. The calculations at the atomic level demonstrate the type-II band alignments of the CsPbI3/BP heterostructure, which make electrons transfer from the perovskite side to monolayer BP. Moreover, the stronger interaction and narrower physical separation of the interfaces can lead to higher charge tunneling probabilities in the CsPbI3/BP heterostructure. Due to different electron affinities, the PbI2-terminated perovskite slab tends to collect electrons from the adjacent materials, whereas the CsI-termination prefers to inject electrons into transport materials. In addition, the interface coupling effect enhances the visible-light-region absorption of the CsPbI3/BP heterostructure. This study highlights the importance of the perovskite termination in the charge transport processes and provides theoretical guidelines to develop high-performance photovoltaic and optoelectronic devices.

As the key equipment in coal-fired power plants, the optimal control problem of ball mill is an important factor affecting the efficient operation of the mill. In this paper, the output model, energy consumption model and unit consumption model of coal pulverizing system are built on the basis of analysis of ball mill running condition. The unit consumption model is used as the genetic algorithm fitness function. The outlet temperature, practical ventilation and coal load of ball mill are chosen as the optimization variables. The algorithm model is built to solve the multi-objective problem of ball mill.

The reliability theory based analysis is more advanced and reasonable compared with the traditional methods for slope stability analysis. Limit equilibrium method is usually used to evaluate the stability of a slope. In this paper, a new reliability analysis method is obtained based on JC method and multi sliding surface method which a new limit equilibrium method developed by Huang. Then, this new method is applied for a wharf slope. The sliding surface get from the safety factor is not the same as that from reliability index though they are close to each other. The safety factor or reliability index get from Fellenius method is smaller than that from other method. The safety factor or reliability index get from multi sliding surface method is close to that from Bishops method. The reliability index can be more reasonable after the standard deviation of the soil property index is deduced with random field theory.

Uniform safety factors are normally assumed in slope stability analysis and this assumption can influence the rationality of the analysis. New analysis methods were obtained based on Fellenius, Bishop and multi sliding surface method to study a failed slope of a port in southern China. The calculation results show that the safety factors of soft soil layers will be overestimated and the safety factors of hard soil layers will be underestimated if soil mass of slope vary widely in the strength. For the failed slope in this paper, the factors obtained with normal methods will be overestimated because of the hard soil layer of this slope.

Horizontal drainage cushion plays a key role in vacuum preloading projects. The traditional horizontal drainage cushion is sand blanket which consumes large amount of sand and is not enviromentally friendly. Several improvements or modifications of horizontal drainage cushion were developed in engineer practices in recent years. Drainage net was used as horizontal drainage cushion in ultra-soft soil improving projects in order to solve the laying problem of sand blanket. Sand ditch was used to deduce the consumption of sand. Direct vacuum preloading method linked the PVDs and filer tubes together in order to improving the transfer efficiency of pressure and canceled the sand blanket at the same time. Low position vacuum preloading method set horizontal drainage cushion below the surface of the ground in order to cancel the sealing membrane.

In urban environment, the soil disturbance induced by shield tunneling can be sensitive because it can cause deformation of the ground and damage the near structure. To study this disturbance in the construction process of Tianjin metro line No.3, in-situ monitoring of pore water pressure, soil pressure and ground settlement were conducted. The pore water pressure was monitored for the soil around the tunnel. The soil pressure was monitored for the soil around the tunnel and on the tunnel face. It was revealed that the pore water pressure and soil pressure changed twice in the tunneling process and these changes were induced by cutting face and grouting at the shield tail. The soil pressure on the tunnel face reached its maximal value when the distance between the cutting face and the sensor elements was around the diameter of the tunnel. Ground settlement developed in the tunneling process. The shape of ultimate settlement trough is closed to the one obtained by Pecks method.

In urban environment, short-distance crossing of shield tunneling to existent piles is an unloading process and can cause adverse effect on the piles. This kind of effect should be controlled. To analysis and control this effect, numerical simulation, field monitoring and optimization of construction parameter were used in this study. To get reasonable calculation parameters for numerical models, field monitoring was conducted. The numerical simulation was utilized to study the process of short-distance crossing and the effect of ground improvement with rotary jet grout pile. The simulation result revealed that the ground improvement is not necessary in soft soil if the pile is long enough. In the later practical tunneling process, the ground improvement in the initial design was canceled. Construction parameters were adjusted in time, such as the strict controlling of synchronized grouting, secondary grouting, rotation speed of cutter head and driving speed. As a result, the displacement of the existent piles was controlled in the tolerable ranges.

The present environmental regulations in China require sludge to be disposed of in a safe and environmentally sound manner. This paper presented an investigation on methods to stabilize wastewater sludge and stability evaluation of stabilized sludge landfill. Laboratory studies were conducted to determine the feasibility of solidifying and stabilizing sludge using fly ash, lime, and clay at varied mixing ratios. Geotechnical properties of stabilized sludge were studied. The test results revealed that the strength of stabilized sludge increased with curing time and the decrease of moisture content. Significant increases in strength were achieved to math suitability for disposal in landfills and a stabilization method was selected based on cost and availability of material. The stability of landfill slope was studied and an optimum slope ratio balancing the safety and economy was presented.

Ultra-soft soil improvement projects are new trend in present China because of the limitation of construction period. Technical problems occur when traditional vacuum preloading method is applied for ultra-soft soil. This paper firstly gave an analysis of the main technical problems which include construction channel problems for building materials and workers, portion division problems of project area, installation problems of prefabricated vertical drains and formation problems of horizontal drainage cushion. Then solutions for these problems were presented. Based on the solutions and traditional vacuum preloading method, a new method for ultra-soft soil improving was put forward. A typical application of this new method was give at the end of this paper.

The slope stability is an important problem for the slope building on the soft clay ground. At present, the vane shear strength is common used to calculate the factor of slope stability at short term. In fact, a lot of cases show that the vane shear strength underestimates the real shear strength of the sliding surface. Therefore, based on Mohr-Coulomb theory, and using the linear relation between the vane shear strength and the depth, a method of converting in-situ vane shear strength into undrained shear strength parameter is presented. Two shear strength parameters c and φ are from statistical regression analysis. The anisotropy, the lateral compression coefficient and the average consolidation degree of the soft clay are considered. The two shear strength parameters are used to calculate the short term safety factor of the slope stability. The safety factor is greater than 1.0 for steady slope.

In urban environment, short-distance undercrossing of shield tunneling to an existent tunnel is an unloading process and can cause adverse effect on the existent tunnel. This kind of effect should be controlled. To analysis and control this effect, numerical simulation, field monitoring and optimization of construction parameter are used. To get reasonable calculation parameters for numerical models, field monitoring is conducted. The numerical simulation is utilized to study the process of short-distance undercrossing. The simulation result revealed that the deformation of the existent tunnel can be beyond the tolerable value unless some measure is adopted, but the deformation can be reduced significantly by improving the ground under the existent tunnel with cement deep mixing method. Construction measures are adopted, such as the strict controlling of synchronized grouting, secondary grouting, rotation speed of cutter head and driving speed. As a result, the deformation of the existent tunnel is controlled in the tolerable value.

On the basis of the limit equilibrium method and the physical significance of Coulomb’s yield criteria, extremum conditions of yield functions is established, which will be the fundamental equations for the limit analysis of soil mass. Once the stress equation along a sliding surface is available, the normal stress on the sliding surface can be obtained, a new limit analysis method, generalized limit equilibrium method (GLEM), can be established. With the generalized limit equilibrium method, an analysis method to solve the problem of slope stability can be obtained without introducing any other assumptions or simplified conditions but the sliding surface. With this algorithm, any discretionally possible sliding surface can be trial calculated and the least value of the calculated results of different sliding surfaces is taken as the safety factor. As long as a selected sliding surface is close to the true sliding surface, the derived safety factor will be approximate to the genuine solution to a problem of slope stability.

In the framework of the topcolor-assisted technicolor (TC2) model, we study the neutral top-Higgs [Formula: see text] production processes [Formula: see text], [Formula: see text] and [Formula: see text]. The results show that the production rates can reach the level of a few fb with reasonable parameter values. With the clean background of the flavor-changing [Formula: see text] channel, the top-Higgs events can possibly be detected at the International Linear Collider (ILC) experiments. Therefore, such neutral top-Higgs production processes offer a useful way to probe for neutral top-Higgs and test the TC2 model directly.

The new colored vector-like heavy fermion $T$ is a crucial prediction in little Higgs models, which plays a key role in breaking the electroweak symmetry. The littlest Higgs model is the most economical one among various little Higgs models. In the context of the littlest Higgs model, we study single production of the new heavy vector-like quark via $e^{-}\gamma$ collisions and discuss the possibility of detecting this new particle in the TeV energy $e^{+}e^{-}$ collider(LC). We find that the production cross section can vary in a wide range($10^{-3}-10^{1}fb$) in most parameter spaces. For the favorable parameter spaces, the possible signals of the vector-like top quark $T$ can be detected via $e^{-}\gamma$ collisions in future $LC$ experiment with $\sqrt{s}=3TeV$ and $\pounds=500fb^{-1}$., Comment: 10 pages,3 figures