Monitoring and Back-Analysis in Dongjian Arch Dam

The monitoring of displacement is one of major measures to ensure the safety of an arch dam. And the back-analysis is a key link in the safety evaluation. This paper presents a case history of monitoring and back-analysis of displacement in Dongjiang Arch Dam, China. The elasticity modulus of dam foundation were determined by back-analysis of displacement for lower water level in the reservoir. The prediction of displacement of dam was compared with the results of monitoring. The suggested procedure of 3D finite element computation coupling solid and temperature stresses can be used for other types of rock engineering

Deformation Prediction for an Underground Opening

For excavation of a large underground opening, how to predict the deformation caused by excavation is a subject of interest to the engineers. In this paper, the main underground opening of Lubuge Hydroelectric Power Station will be cited to explain the method predicting its deformation. The successful application shows that the method called MDBD could, perhaps, be used for deformation prediction of other large underground excavations if they satisfy some special conditions basically

SVSI: Fast and Powerful Set-Valued System Identification Approach to Identifying Rare Variants in Sequencing Studies for Ordered Categorical Traits: SVSIfor Genetic Association Studies

For genetic association studies that involve an ordered categorical phenotype, we usually either regroup multiple categories of the phenotype into two categories (“cases” and “controls”) and then apply the standard logistic regression (LG), or apply ordered logistic (oLG) or ordered probit (oPRB) regression which accounts for the ordinal nature of the phenotype. However, these approaches may lose statistical power or may not control type I error rate due to their model assumption and/or instable parameter estimation algorithm when the genetic variant is rare or sample size is limited. Here to solve this problem, we propose a set-valued (SV) system model, which assumes that an underlying continuous phenotype follows a normal distribution, to identify genetic variants associated with an ordinal categorical phenotype. We couple this model with a set-valued system identification algorithm to identify all the key system parameters. Simulations and two real data analyses show that SV and LG accurately controlled the Type I error rate even at a significance level of 10−6 but not oLG and oPRB in some cases. LG had significantly smaller power than the other three methods due to disregarding of the ordinal nature of the phenotype, and SV had similar or greater power than oLG and oPRB. For instance, in a simulation with data generated from an additive SV model with odds ratio of 7.4 for a phenotype with three categories, a single nucleotide polymorphism with minor allele frequency of 0.75% and sample size of 999 (333 per category), the power of SV, oLG and LG models were 70%, 40% and <1%, respectively, at a significance level of 10−6. Thus, SV should be employed in genetic association studies for ordered categorical phenotype

The 102 Landslide: human-slope interaction in SE Tibet over a 20-year period

The evolution of large- scale landslides should be studied because, over long periods of time, primary remediation measures may suffer reduced efficiency or have to be adjusted many times. The 102 Landslide in southeast Tibet, which originally formed in 1991 with a volume of 5.1 million m(3) and still exhibits post- failure activity, provides a distinctive case study. The landslide evolved from earthquake destruction and unloading, rainfall- triggered sliding, and debris flow to sands sliding slopes. The NE ringed scarp receded by 38.96 m during a five- year period (2003-2008). The total recession was 160 m with a total area of 2500 m (2) during a 17-year period (1991-2008). Although several types of remediation measures were applied and were temporarily effective, the normal function of the Sichuan-Tibet Highway was affected by landslide reactivation from time to time. Actual effects of the engineering measures such as retaining walls, prestressed anchor cables, and drainage ditches confirm that hasty governance of this type of large-scale landslide is generally unfeasible over long time periods. Finally, an approach involving a tunnel running backward from the front face has been adopted as a permanent solution to large-scale moraine slope failures: This engineering practice has been in progress since April 2012. This paper describes the evolution of the 102 Landslide, the engineering interventions to mitigate the effects of the landslide on the Sichuan-Tibet Highway, and the choice of tunneling as a final mitigation measure. The present study concludes that approaches that allow escape from developing geohazards should always be the initial choice.N

Water–Air Interface Greenhouse Gas Emissions (CO2, CH4, and N2O) Emissions Were Amplified by Continuous Dams in an Urban River in Qinghai–Tibet Plateau, China

Continuous dams may lead to great variation in greenhouse gas (GHG) emissions from rivers, which contribute more uncertainty to regional carbon balance. This study is among the first to determine water&ndash;air interface GHGs (CO2, CH4, and N2O) in a river with continuous dams in plateau city. Combined static-chamber gas and meteorological chromatography were utilized to monitor the GHGs emission flux at the water&ndash;air interface within four continuous dams in the Huoshaogou River in the Qinghai&ndash;Tibet Plateau, China. A variation coefficient (VC) and amplification coefficient (AC) were designed to detect the influence of continuous dams on GHG emissions. Results indicate that (1) cascade dams presented an amplifying effect on GHGs emissions from the water-air interface. The VCs of three types of GHGs are 3.7&ndash;6.7 times higher than those of the undammed area. The ACs of three types of GHGs are 2.7&ndash;4.1 times larger than environmental factors; (2) the average GHG emission fluxes in some dams are higher than that of the first dam, indicating that an amplifying effect may have been accumulated by some continuous dams; (3) EC, pH, Twater, Tair and TDS are found to be principle influencing factors of GHG emission and light intensity, Twater, TOC (plant), TN (sediment) and TOC (sediment) are found to be associated with accumulative changes in GHG emission

Moving-Vehicle Identification Based on Hierarchical Detection Algorithm

The vehicle detection method plays an important role in the driver assistance system. Therefore, it is very important to improve the real-time performance of the detection algorithm. Nowadays, the most popular method is the scanning method based on sliding window search, which detects the vehicle from the image to be detected. However, the existing sliding window detection algorithm has many drawbacks, such as large calculation amount and poor real-time performance, and it is impossible to detect the target vehicle in real time during the motion process. Therefore, this paper proposes an improved hierarchical sliding window detection algorithm to detect moving vehicles in real time. By extracting the region of interest, the region of interest is layered, the maximum and minimum values of the detection window in each layer are set, the flashing frame generated by the layering is eliminated by the delay processing method, and a method suitable for the motion is obtained: the real-time detection algorithm of the vehicle, that is, the hierarchical sliding window detection algorithm. The experiments show that the more layers are divided, the more time is needed, and when the number of detection layers is greater than 7, the time change rate increases significantly. As the number of layers decreases, the detection accuracy rate also decreases, resulting in the phenomenon of a false positive. Therefore, it is determined to meet the requirements of real time and accuracy when the image is divided into 7 layers. It can be seen from the experiment that when the images to be detected are divided into 7 layers and the maximum and minimum values of detection windows are 30 × 30 and 250 × 250, respectively, the number of sub-windows generated is one thirty-seventh of the original sliding window detection algorithm, and the execution time is only one-third of the original sliding window detection algorithm. This shows that the hierarchical sliding window detection algorithm has better real-time performance than the original sliding window detection algorithm

Powertrain modeling and performance simulation of a novel flywheel hybrid electric vehicle

To improve vehicle performance and energy utilization, a novel planetary gear set based flywheel hybrid electric powertrain (PGS-FHEP) is proposed. The PGS-FHEP involves an internal combustion engine, a planetary gear set that integrated a control motor and an energy storage flywheel, which combines the high efficiency of the mechanical flywheel energy storage system with the flexible and controllable characteristics of the electric motor. The powertrain is analyzed and modeled using lever analogy method, and a rule-based control strategy is designed and verified under different test cycles. The simulation results indicate that compared with the traditional manual transmission vehicle, the fuel economy of the vehicle equipped with PGS-FHEP can be improved by more than 50%, and the acceleration performance can be increased by 28.01%. Up to 60.61% of vehicle kinetic energy can be recovered by PGS-FHEP, among which 37.85% can be directly captured by the energy storage flywheel. In addition, the battery charging power is reduced, which is beneficial to prolong the battery life

Back analysis of long-term stability of a 92 m span ancient quarrying cavern

Long-term stability of large-span caverns is a challenging issue for design and construction of underground rock engineering. The Heidong cavern group consisting of 21 caverns was constructed about 1400 years ago for quarrying in massive Cretaceous tuff. The cavern No. 5 of the Heidong cavern group is characterized by an unsupported span up to 92 m, with the overburden thickness of only 3–25 m. To analyze its long-term stability, a detailed investigation was conducted to obtain its geometry and rock mass characteristics, and to monitor surrounding rock displacements. Based on field survey and laboratory tests, numerical simulations were performed using the finite difference code FLAC3D. The analysis results revealed that for the long-term stability of the cavern No. 5, some major factors should be carefully considered, such as cavern excavation method in hard massive rocks, site investigation using trial pits, tools like short iron chisel and hammer for manual excavation, geometric dome roof, and waste rocks within abutment or on the floor. The highlights of the technologies obtained from this large-scale ancient underground project can provide reference for other similar project excavations in practice

Engineering Application and Prediction of the Influence Area of the Rockfall Hazards

The identification of potential rockfall and the accurate prediction of its trajectory are critical in prevention and mitigation of rockfall hazard. It is an important precondition to assess the uncertainty of rockfall motion, study the effective identification technology of potential rockfall, predict the rockfall trajectory, and calculate the threatened area by rockfall hazards. In this study, field investigations and numerical simulations were carried out to identify potential rockfall on a weathered rock slope. As a case study, our calculations results show that the area of tensile stress concentration and plastic failure is the potential area where the rockmass will fall off the surface of the weathered rock slope. A mathematical model for calculating the rockfall influence area of the weathered rock slope was established based on the optimization theory, neural network technology, and genetic optimization algorithm. The rockfall influence area of the weathered rock slope was determined using maximum horizontal distance of rockfall in the specified slope cross sections and described on the topographic map using spline curves to form a closed possibly vulnerable area. As a case study, our calculations confirm that the distributions of the plastic failure and tensile stress areas obtained from the numerical simulations are consistent with the dangerous rock masses identified by field investigations at Guanyindong Slope that is a popular tourist scenic spot in Zhejiang Province, China. In this study, it has been indicated that the influence area can be used as the basis for the design of passive protection methods for rock slopes vulnerable to rockfall hazards