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Photovoltaic power generation is gradually developing into a massive power industry with the maturity of renewable energy power generation technologies. Photovoltaic power generation is greatly affected by external factors and the output power is characterized by randomness and indirectness, which poses a great challenge to photovoltaic grid-connection. A hybrid improved multi-verse optimizer algorithm (HIMVO) is proposed to optimize the support vector machine for photovoltaic output prediction. HIMVO algorithm introduces chaotic sequences to initialize the population, which significantly enhances the convergence rate of the algorithm compared with the multi-universe optimizer algorithm. This study applied particle swarm optimization algorithm, dragonfly algorithm, multi-universe optimizer algorithm and HIMVO to testify the availability of the hybrid improved multi-verse optimizer support vector machine model (HIMVO-SVM). The results indicate that HIMVO algorithm has better optimization ability and stability. The four models, HIMVO-SVM, multi-verse optimizer support vector machine, particle swarm optimization support vector machine, back propagation and radical basis function neural network are used to predict output in three different weather types. The results indicate that the model has higher prediction accuracy and stability. The mean square error value of the HIMVO-SVM model decreases by at least 0.0026, 0.0030 and 0.0012, and the mean absolute percentage error value decreases by at least 3.6768%, 1.9772% and 2.7165%, respectively. The proposed method is beneficial to the prediction of output power and conduces to the economic dispatch of the grid and the maintenance of the stability of the power system.

The N-S trends normal faults are widespread through the whole Tibetan Plateau. It records key information for the growth and uplift of the Tibetan Plateau. Numerous models are provided to explain the causes of rifting in the Tibetan Plateau based on the low-temperature thermochronology1. With the developments of the geophysical and magmatic geochemistry methods and its applications on the Tibetan Plateau, we could gain more profound understanding on the sphere structure of the Tibetan Plateau. This would give us more clues on how the deep process affect the formation and evolution of the shallow normal faults. However, few researchers pay attention on this and the relationship between the surface evolution and deep process of these faults. In order to solve these puzzles, we collected the published thermochronology data, magnetotelluric data, faults-related ultrapotassic, potassic and the adakitic rocks ages and present-day GPS measurements. We find that the distribution of the N-S trends normal faults are closely related to the weak zones in the middle to lower crust (15-50 km) revealed by the magmatism and magnetotelluric data2. Besides, the present-day GPS data show that the E-W extension rates match well with the eastward movements speeds interior Tibetan Plateau3. Combined with the thermochronology data (25-4 Ma), we concluded that 1.The weak zone in the middle to lower crust influence the developments and evolution of the N-S trends normal faults. 2. The material eastward flow enhance the N-S normal faults developments. 3. The timing of the middle to lower crustal flow may begin in the Miocene.Key words: N-S trends normal faults; Thermochronology; Magnetotellurics; Magmatism; GPS Measurements; middle to lower crustal flowReferences:1Lee, J., Hager, C., Wallis, S.R., Stockli, D.F., Whitehouse, M.J., Aoya, M. and Wang, Y., 2011. Middle to Late Miocene Extremely Rapid Exhumation and Thermal Reequilibration in the Kung Co Rift, Southern Tibet. Tectonics, 30(2).2Pang, Y., Zhang, H., Gerya, T.V., Liao, J., Cheng, H. and Shi, Y., 2018. The Mechanism and Dynamics of N-S Rifting in Southern Tibet: Insight from 3-D Thermomechanical Modeling. Journal of Geophysical Research: Solid Earth.3Zhang, P.-Z., Shen, Z., Wang, M., Gan, W., Bürgmann, R., Molnar, P., Wang, Q., Niu, Z., Sun, J., Wu, J., Hanrong, S. and Xinzhao, Y., 2004. Continuous Deformation of the Tibetan Plateau from Global Positioning System Data. Geology, 32(9).Acknowledgements:We thank Shi-Ying Xu, Xu Han, Bo-Rong Liu for collecting data. Special thanks are given to Dr. Guang-Hao Ha and Professors Jin-Gen Dai, Le-Tian Zhang，Ya-Lin Li and Cheng-Shan Wang for many critical and constructive comments.

In order to constrain the detrital provenance of the siliciclastic rocks, palaeogeographic variations, and crustal growth history of central China, we carried out simultaneously in situ U–Pb dating and trace element and Hf isotope analyses on 368 detrital zircons obtained from upper Permian–Triassic sandstones of the Songpan terrane, eastern Tibetan Plateau. Two groups of detrital zircons, i.e. magmatic and metamorphic in origin, have been identified based on cathodoluminescence images, zircon Ti-temperatures, and Th/U ratios. Our data suggest that the derivation of siliciclastic rocks in the Songpan terrane was mainly from the Qinling, Qilian, and Kunlun orogens, whereas the Yangtze and North China Cratons served as minor source areas during late Permian–Triassic times. The detrital zircons from Middle–Late Triassic siliciclastic rocks exhibit wide age spectra with two dominant populations of 230–600 Ma and >1600 Ma, peaking at ~1.8–1.9 Ga and ~2.4–2.5 Ga, suggestive of a derivation from the Qinling, Qil...

The linkage of the South Asian High (SAH) to the southern annular mode (SAM) during the boreal summer is addressed. The results show that the SAH correlated well with the Southern Hemispheric subtropical high (SSH) and SAM, which exhibits that their recent positive trends are associated with each other. During the positive SAH anomalies years, roughly speaking, the sea level pressure (SLP) and the zonal surface wind (u10) are analogous to that of the positive SAM phase, but they also show an anomalous zonal-wave-3-like (ZW3-like) pattern over the mid latitudes. The surface temperature (ST) variations are not similar to the SAM. Nevertheless, these changes are related with the anomalous cyclones and meridional surface wind (v10). The relationship between the SAH and SAM is also a manifestation of the interhemispheric interaction, and this study contributes to the understanding of the global change.

Large topography can affect the global climate change significantly. Many studies have revealed that the altitude of the Tibetan Plateau (TP) is related to the Asian regional climate. In order to find how the global-scale atmospheric circulation changes in response to the TP uplift in summer, a fully coupled model, Community Earth System Model (CESM), was used in this paper. Four experiments were run with the altitude of TP set to 25%, 50%, 75%, and 100% of the modern height, respectively (referred to as TP25, TP50, TP75, TP100 experiments). The results show that the uplift of the TP causes the change of the subtropical circulation over the northern hemisphere as well as the southern hemisphere. In the TP25 experiment, the South Asian High (SAH) at the 150mb is comparatively weak, and with the elevated surface heating, the vertical motion in the middle troposphere strengthens greatly. The ascending air over the TP leads to the forming and sustaining of the SAH, a dominate subsystem of the upper troposphere. The perturbation of the SAH propagates in the upper troposphere and stimulates stronger planetary waves on the globe and it also affects the circulation in the low level atmosphere. The subtropical highs over seal level strengthen over the Southern Ocean as well as the North Pacific and Atlantic Oceans. Furthermore, the westerlies around the Antarctica become stronger with the increasing altitude of the TP. This is meaningful that the stronger westerlies may be a forcing to accelerate the Cenozoic global cooling during the geological history.

This paper presents an improved GSA-GA algorithm to achieve bad-data detection, identification and correction in power grid. The algorithm combines BP neural network, K-means clustering algorithm, gap statistical algorithm (GSA) and genetic algorithm together. BP neural network preprocesses the data, K-means algorithm clusters the preprocessed data and GSA algorithm determines the optimal clustering number and identifies the presence of bad data. After identifying the bad data, GA-BP algorithm is used to correct the identified data. This paper takes simulation tests to verify the proposed algorithms correctness and effectiveness based on actual grid data considering multiple types of existed bad data.

Voltage stability of power grid would be affected greatly by the connection of large-scale wind farms. Conventional continuous power flow method can not accurately simulate the system’s operation when wind farms are connected to power gird. A new continuous power flow method is proposed, considering auto-disconnection of large-scale wind farms. The step-size control segment is improved in this algorithm in order to simulate the operation characteristics of wind farm and determine the precise time when a certain wind farm is cut off.

DC/DC converters are known to exhibit bifurcations and chaos if switching actions are governed by feedback control. A dynamic controller based optimal control method is presented to control the chaos behavior and maximize the conversion efficiency of a zero-voltage-switching (ZVS) buck converter operating in continuous conduction mode (CCM). The simulation results show the effectiveness of the proposed scheme.

Understanding why continental deformation departs from the theory of plate tectonics requires a detailed knowledge of three-dimensional structures at a lithospheric scale. In Tibet, the end-member models of continental deformation make distinctively different predictions on strain distribution and contrasting structural geometry as a function of depth. Specifically, the thin-viscous-sheet model predicts vertically coherent deformation while channel-flow and continental-subduction models predict the presence of sub-horizontal detachment zones within or at the base of the Tibetan crust during the Cenozoic deformation. To differentiate the above models, we conducted a high-resolution seismic-reflection survey across the active left-slip Kunlun fault and its nearby contractional structures. The results of this work show that the actively deforming middle Tibetan crust is dominated by discrete sub-horizontal simple-shear zones that terminate the sub-vertical, left-slip Kunlun fault above and mantle-cutting thrusts below. The flat shear zones appear to act as roof and floor thrusts of large duplex structures that transfer shortening strain from locally deformed and coupled lower crust and mantle lithosphere below to the high-strain domains of the upper crust above. The middle-crustal strain-transfer model proposed here implies that the weak Tibetan middle crust may not be active everywhere during the Indo-Asian collision. It also predicts that the kinematics of the activated portions of the middle crust, whether being deformed by simple shear or channel-flow deformation, may vary from place to place, depending strongly on the lateral variation of mechanical strength at different depths of the lithosphere. Our approach of establishing the kinematics of middle-crust deformation departs significantly from the early work that emphasizes exclusively the role of vertically varying rheology in controlling the mode of continental deformation.

The molten liquid flow inside a packed bed is a familiar momentum transportation phenomenon in a blast furnace. With regard to the reported mathematical models describing the liquid flow within a packed bed, there are some obstacles for their application in engineering design, or some limitations in the model itself. To overcome these problems, the forces from the packed bed to the liquid flow were divided into appropriate body and surface forces on the basis of three assumptions. Consequently, a new mathematical model was built to present the liquid flow inside the coke bed in a blast furnace. The mathematical model can predict the distribution of liquid flowrate and the liquid flowing range inside the packed bed at any time. The predicted results of this model accord well with the experimental data. The model will be applied considerably better in the simulation on the ironmaking process compared with the existent models.

The Himalayan orogen consists of three major lithologic units that are separated by two major north-dipping faults: the Lesser Himalayan Sequence (LHS) below the Main Central Thrust (MCT), the Greater Himalayan Crystalline Complex (GHC) above the MCT, and the Tethyan Himalayan Sequence (THS) juxtaposed by the South Tibet Detachment fault (STD) over the GHC. Due to widespread metamorphism and intense deformation, differentiating the above three lithologic units is often difficult. This problem has been overcome by the use of Sm-Nd isotopic analysis. The previous studies suggested that the LHS can be clearly distinguished from the GHC and THS by their Nd isotope compositions. However, the lack of detailed and systematic Sm-Nd isotopic studies of the THS across the Himalaya in general has made differentiation of this unit from the nearby GHC impossible, as the two appear to share overlapping Nd compositions and model ages. To address this problem, we systematically sampled and analyzed Nd isotopes of the THS in southeastern Tibet directly north of Bhutan. Our study identifies two distinctive fields in a ɛ Nd-T DM plot. The first is defined by the ɛ Nd(210 Ma) values of −3.45 to −7.34 and T DM values of 1.15 to 1.29 Ga from a Late Triassic turbidite sequence, which are broadly similar to those obtained from the Lhasa block. The second field is derived from the Early Cretaceous meta-sedimentary rocks with ɛ Nd(130 Ma) values from −15.24 to −16.61 and T DM values from 1.63 to 2.00 Ga; these values are similar to those obtained from the Greater Himalayan Crystalline Complex in Bhutan directly south of our sampling traverse, which has ɛ Nd(130 Ma) values of −10.89 to −16.32 and Nd model ages (T DM) of 1.73 to 2.20 Ga. From the above observations, we suggest that the Late Triassic strata of the southeast Tibetan THS were derived from the Lhasa block in the north, while the Early Cretaceous strata of the THS were derived from a source similar to the High Himalayan Crystalline Complex or Indian craton in the south. Our interpretation is consistent with the existing palaeocurrent data and provenance analysis of the Late Triassic strata in southeastern Tibet, which indicate the sediments derived from a northern source. Thus, we suggest that the Lhasa terrane and the Indian craton were close to one another in the Late Triassic and were separated by a rift valley across which a large submarine fan was transported southward and deposited on the future northern margin of the Indian continent.

The molten liquid discrete flow inside a packed bed is a typical transport phenomenon in the blast furnace. As for the reported mathematical models presenting the liquid discrete flow within the packed bed, there are some barriers for their application to an engineering scale-up, or some imperfections in model descriptions. To overcome these deficiencies, the effects of the packed bed on the liquid discrete flow have been divided into resistance action and dispersal action, and appropriate descriptions have been given for the two actions, respectively. Consequently, a new mathematical model has been built to present the liquid discrete flow inside a coke bed in the blast furnace. The mathematical model can predict the distribution of liquid flux and the liquid flowing range inside the packed bed at any time. The prediction of this model accords well with the experimental data. The model will be much better for the simulation of the ironmaking process, compared with the existent model.

We gives a detailed description of the magnetic fabrics of the rocks from the Nyalam region, south Tibet in order to fathom the deformational phases and processes in the Himalayan orogenic belt. The characteristics of the magnetic fabrics indicate that the anisotropy (P) of magnetic susceptibility in the rocks is highest in the schist 1km north of Zham Town, with a maximum value of 1.72, while lowest in the rocks 1km south of Kangshanqiao, with a minimum value of 1.13. The percentage anisotropies (H) of magnetic susceptibility range between 11.82% and 45.07%, indicating that the rocks in these places were once subjected to severe thrusting and plastic deformation during the early stages of the collision between the Indian plate and the Eurasian plate. The Nyalam and Rouqiecun Group Complexes may be considered as a giant ductile shear zone. The magnetic lineations (L) vary between 1.02 and 1.09, and magnetic foliations (F) between 1.06 and 1.60. The magnetic lineations are apparently better developed than the magnetic foliations. The shape factors of magnetic ellipsoids (T) range between 0.19 and 0.76, and the Eccentricity (E) of the magnetic ellipsoids between 1.04 and 1.49. The magnetic ellipsoids tend to take the shape of a flattened ellipsoid. From the region 1km north of Zham Town to Rouqiecun, the main axis (D3) of mean minimum magnetic ellipsoids is oriented S-N (with the exception of the MA9 1 km north of Zham Town), and main axial dip angle (I3) > 51ο, even up to 72.6ο. The results of research have demonstrated that the combination of NS-directed compressional stress and NWW-trending structural plane resulted in the strike-slipping shear of dextral ductile oblique thrusting, rapid uplifting of mountain masses and high topographic reliefs on the Higher Himalayan crystalline basement. The locally developed elongated magnetic ellipsoids indicate that the combination of gravitational potential energy of the mountain masses and northward compressional force caused by the Indian plate led to nearly NS-trending extension and collapse and the formation of a dextral ductile shear zone similar to tilted structures.

A sequence of BCU classifiers for online dynamic contingency screening is developed and their theoretical basis is provided. The design objective of the BCU classifiers is to ensure that unstable (single-swing or multiswing) contingencies be completely captured and that the number of contingencies needed for further analysis be significantly reduced. An architecture for online dynamic security assessments consisting of the BCU classifiers and an online transient stability (time-domain) simulation program is presented. The effectiveness of the developed BCU classifiers and proposed architecture is evaluated with very promising results using 7120 contingencies on a 50-generator, 145-bus power system and a 202-generator, 1293-bus real power system data.

A number of composite sedimentary basins are present on the Qinghai-Tibet (Tibetan) Plateau. Some of these basins are filled with marine sediments, whereas others are fault-bounded continental depressions. Mixed source-rock types are present, of variable organic matter content; source rocks are mainly carbonates and secondarily mudstones. Vitrinite reflectance and biomarker analyses show that Mesozoic and Cenozoic source rocks have reached the peak stages of oil generation; older source rocks may have generated natural gas. The hydrocarbon reserves of these basins are believed to total ∼37.2 billion barrels. The Qiangtang-Qamdo basin probably has the greatest potential for oil exploration.

Given the current operating condition (obtained from the real-time data), the near-term load demand at each bus (obtained from short-term load forecast), and the generation dispatch (say, based on economic dispatch), we present in this paper a load margin measure (MW and/or MVAr) to assess the system's ability to withstand the forecasted load and generation variations. We also present a method to predict near-term system voltage profiles. The proposed look-ahead measure and the proposed voltage prediction are then applied to contingency selections for the near-term power system in terms of load margins to collapse and of the bus voltage magnitudes. We evaluate the proposed look-ahead measure and the voltage profile prediction on several power systems including a 1169-bus power system with 53 contingencies with promising results.

This study describes the change of organic degradation capability and soluble microbial products (SMP) generated in activated sludge under continuous exposure to Zn (II) in a sequencing batch reactor (SBR). In 338 days of operation, the added Zn (II) concentrations were gradually increased from 50 to 100, 200, 400 to 600 and 800 mg/L. Results showed that after adaptation, the activated sludge could endure 400mg/L Zn (II) without showing evident reduction in organic degradation ability (92±1% of chemical oxygen demand (COD) removal in stable state). However, when 600 and 800 mg/L Zn (II) were applied, the effluent water quality significantly deteriorated. Meanwhile, under increasing Zn (II) concentrations, the SMP content in the activated sludge, together with its main biochemical constituents, first increased slightly below 400mg/L of Zn (II), then rose sharply under 600 and 800 mg/L Zn (II). Furthermore, a close correlation was found between SMP content and effluent soluble COD in both the Experimental Reactor and Control Reactor. In addition, the Zn (II) concentrations in the effluent and SMP extraction liquid were further analyzed and discussed to reveal the role that SMP constituents played in defense and resistance to the toxicity of Zn (II).

Because of large fluctuations and strong randomness of active power generated by renewable energy resources, taking into account the constraints such as battery life cycle, a new battery energy storage system control method based on real-time state-of-charge and variable filter time constant is presented. This method could compensate the fluctuation composition of a particular frequency band of power. At the same time, filter time constant is adjusted in order to stabilize the value of SOC in a certain range, and over-charging and over-discharging of the battery is avoided. A photovoltaic (PV) and battery hybrid system modeled by PSCAD is tested to verify the validity of this method.

High-performance processor architectures are moving toward the integration of more processing cores on a single chip. PCs and parallel computer systems will have higher computing performance. It is very meaningful for power system simulation, online stability assessment and control. But traditional serial and parallel software can not fully exploit multi-core's capability without parallelizing restructure. In this paper, parallel simulation algorithms are analyzed and software restructure strategies are studied for multi-core processor platforms. The research indicates that: (1) For PCs, implicit parallel strategy with OpenMP is easier to implement and explicit parallel strategy with MPI or Pthreads is more adaptable to large-scale system simulation. (2) For clusters and distributed systems, MPI+OpenMP hybrid programming is convenient and multilevel partitioning is potential. Both methods provide better speedup.

Diagenetic effect during burial on the hydroxyapatite in enamel and dentin from fossil human and animal teeth was examined, using X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). For the enamel and dentin of all fossil teeth, XRD patterns exhibit bulge line and overlap between major reflections of hydroxyapatite, and the crystallinity of hydroxyapatite is low. For each infrared spectrum, H2O and OH(-) have distinct peaks of absorbance, and PO4(3-) and CO3(2-) ions have intensive infrared vibration modes at the fundamental wave numbers. The component of hydroxyapatite of all fossil teeth is similar to the modern biological hydroxyapatite. Furthermore, the index (PCI) which reflects the hydroxyapatite crystallinity of each sample ranges from 2.4 to 4.0 while the index (BPI) reflecting the amount of type B carbonate to phosphate indicates that the values of CO3(2-) content in hydroxyapatite are rather high, accordingly the crystallinity of all fossil hydroxyapatites are poor. It could be concluded that little alteration of hydroxyapatites from fossil human and animal teeth occurred in the process of diagenesis in Jinsha Relict, Chengdu, China.

A very fast method for computing the saddle-node bifurcation point of general nonlinear systems with decoupled parameters is developed in this paper. The speed of the developed method is achieved through two factors. One factor is a new set of characteristic equations for the saddle-node bifurcation point which is of dimension n+1, instead of 2n+1, which is traditionally required in n-dimensional decoupled parameter-dependent nonlinear equations. The other factor is a new effective scheme for estimating the location of a desired saddle-node bifurcation point and its associated bifurcation value. The estimated location and value provide a good initial guess for computing the desired saddle-node bifurcation points. The proposed solution method has been applied to a set of 416-dimensional decoupled parameter-dependent nonlinear equations to illustrate its effectiveness and accuracy.

The objective of this paper is to present a powerful procedure for identifying severe single branch outage contingencies with respect to saddle-node bifurcation, given a power system operating point, a load demand forecast and a generation dispatch. A novel two-stage look-ahead ranking algorithm for saddle-node bifurcation are described. The first stage is based on a branch MVAr participation index and the second stage is based on sensitivity analysis. The distinguishing features are the ability: (i) to screen out the weak contingencies; and (ii) to directly estimate the strong contingency bifurcation values. The novel two-stage look-ahead ranking algorithm has been applied to a 3493 bus power system with promising results.