Left Slope Research Articles

Efficient 3-D reliability analysis of the 530 m high abutment slope at Jinping I Hydropower Station during construction

Reliability-based slope stability analysis and design show promise, but few attempts have been made to study the 3-D reliability of high rock slopes. This paper aims to investigate the 3-D reliability of practical rock slopes and to explore the effects of reinforcement measures on slope reliability. A non-intrusive stochastic finite difference method is adopted to perform 3-D reliability analysis of high rock slopes, in which response surface functions are adopted to establish the explicit functions between the factors of safety for multiple slope failure modes and the significant random variables. The left abutment slope at Jinping I Hydropower Station in China is taken as a case study. A parametric sensitivity analysis is carried out to identify the significant uncertain parameters. The effects of two reinforcement measures, namely pre-stressed cables and shear-resistant concrete plugs, on the reliability of the rock slope during construction are highlighted. The results indicate that the 3-D reliability of complex rock slopes can be efficiently evaluated using a non-intrusive stochastic finite difference method. It provides an effective tool for solving 3-D reliability problems of complex rock slopes in practice. The combined support system with pre-stressed cables and three shear-resistant concrete plugs adopted in the Jinping I left abutment slope can effectively restrain the slope deformation and ensure the slope stability during construction. The disturbances induced by the excavation blasting during construction have a significant influence on the engineered slope reliability.

Trunk muscle activation, fatigue and low back pain in tennis players.

To analyze differences in trunk endurance time, fatigue and activation in tennis players with and without low back pain. Observational study, cross-sectional design. Thirty-five tennis players completed an isometric trunk endurance protocol comprising four tasks (flexor, extensor and side bridge tests). LBP history was obtained through the Nordic Musculoskeletal Questionnaire. Endurance time was recorded for each test. Surface electromyographic activity was recorded bilaterally from rectus abdominis, external obliques, iliocostalis lumborum and longissimus thoracis. Average electromyographic amplitude and median frequency slopes during the tests were calculated and used as indicators of change in muscle activation and fatigue. Asymptomatic players had greater flexor (p=0.004) and right side bridge (p=0.043) endurance times. These players produced a greater increase in avrEMG during the right side bridge test for the left ES-I (p=0.046) and right EO (p=0.008). Players with LBP in the last 7 days showed reduced activation of the left (p=0.014) and right (p=0.013) ES-I and left longissimus thoracis (ES-L, p=0.047) in the extensor test. In the left side bridge test there was a lower avrEMG slope of the left EO (p=0.024) and left RA MF slope (p=0.011). In the right side bridge test a lower left ES-I avrEMG slope was found (p=0.048). Symptomatic players show lower activation of extensor muscles, less co-contraction patterns and less abdominal endurance. Tennis coaches and clinicians should consider these factors in their approach to players with LBP.

Seasonal differences in seismic responses of embankment on a sloping ground in permafrost regions

Because of its direct influence on the amount of unfrozen water and on the strength of intergranular ice in a frozen soil, temperature has a significant effect on all aspects of the mechanical behavior of the active layer in which temperature fluctuates above and below 0°C. Hence seismic responses of engineering structures such as embankment on a sloping ground in permafrost regions exhibit obvious differences with seasonal alternation. To explore the distinctive seismic characteristics of a railway embankment on the sloping ground in permafrost regions, a coupled water-heat-dynamics model is built based on theories of heat transfer, soil moisture dynamics, frozen soil mechanics, soil dynamics, and so on. A well-monitored railway embankment on a sloping ground in Qinghai–Tibet Plateau is taken as an example to simulate seismic responses in four typical seasons in the 25th service year. The numerical results show that seismic acceleration, velocity and displacement responses are significantly different in four typical seasons, and the responses on October 15 are much higher among the four seasons. When the earthquake is over, there are still permanent differential deformations in the embankment and even severe damages on the left slope on October 15. Therefore, this position should be monitored closely and repaired timely to ensure safe operation. In addition, the numerical model and results may be a reference for maintenance, design and study on other embankments in permafrost regions.

Polarity-reversed ultra-wideband monocycle pulse generation with dual-channel multicasting in a photonic crystal fiber

This paper proposes and demonstrates a novel scheme of a two-channel-output ultra-wideband monocycle pulse generator consisting of a 100 m dispersion-flattened highly nonlinear photonic crystal fiber and two optical bandpass filters. Based on the cross-phase modulation effect in a dispersion-flattened highly nonlinear photonic crystal fiber, two polarity-reversed ultra-wideband monocycle pulses simultaneously output from two different channels are successfully achieved by appropriately locating the probe wavelength at the left linear slope and the right linear slope of the two optical bandpass filters transmission spectra, respectively. The full width at half-maximum and a fractional bandwidth of 24 ps and 260% for a positive pulse, 24 ps and 251% for a negative pulse are obtained. Moreover, the influences of input signal powers, the polarization misalignment between the data light and the continuous wave probe light, and probe wavelength variation on the double output ultra-wideband signals quality are also investigated. The results show that the system has some tolerance to both the input signal power fluctuation and the slight polarization mismatch and even can efficiently operate with a widely tunable wavelength range. This makes it very attractive for engineering applications in future multiuser ultra-wideband-over-fiber communication systems.

On the orbital stability of Gaussian solitary waves in the log-KdV equation

We consider the logarithmic Korteweg–de Vries (log-KdV) equation, which models solitary waves in anharmonic chains with Hertzian interaction forces. By using an approximating sequence of global solutions of the regularized generalized KdV equation in with conserved L2 norm and energy, we construct a weak global solution of the log-KdV equation in a subset of . This construction yields conditional orbital stability of Gaussian solitary waves of the log-KdV equation, provided that uniqueness and continuous dependence of the constructed solution holds.Furthermore, we study the linearized log-KdV equation at the Gaussian solitary wave and prove that the associated linearized operator has a purely discrete spectrum consisting of simple purely imaginary eigenvalues in addition to the double zero eigenvalue. The eigenfunctions, however, do not decay like Gaussian functions but have algebraic decay. Using numerical approximations, we show that the Gaussian initial data do not spread out but produce visible radiation at the left slope of the Gaussian-like pulse in the time evolution of the linearized log-KdV equation.

Stability assessment of a high rock slope by strength reduction finite element method

The dam site of Jinping-I hydropower station is located on the Yalong River and has complicated geological conditions. A steep rock slope with a height of about 530 m will be built after excavation of the arch dam abutment. There exists a huge wedge failure block in the left abutment slope which has a vital influence on the construction schedule and safety of the whole project. To evaluate the stability of the slope during construction, the strength reduction finite element method (SRFEM) is employed to simulate progressive failure of the huge block. The criteria for judging the failure of slopes are discussed for the SRFEM. The results from the proposed SRFEM indicate that excavation of the spandrel groove slope below an elevation of 1,885 m would drastically deteriorate the stability of the huge block. The implementation of shear-resistance tunnels effectively increases the safety factor of the huge block and ensures the stability of the left abutment slope.

Stability analysis of statically indeterminate blocks in key block theory and application to rock slope in Jinping-I Hydropower Station

Using the movability analysis in block theory, one can easily determine all movable blocks. However, only for a movable block with no more than two structural surfaces, called the statically determinate block, can the factor of safety be determined by the static analysis, which limits more extensive application of key block theory. In order to analyze general movable blocks with multiple structural planes, an optimization model for solving the safety factor of blocks is built in this paper. In the model, the safety factor as well as the normal stress on the slip surface is taken as independent variables; and the objective function is specified as the safety factor alone. The statically admissible conditions include the system of equilibrium equations, non-negativity of both normal stress on the slip surface and thrust inside the block. Since the objective function is linear and the constraint functions are polynomials of no more than degree-2, it is weak in nonlinearity and can be solved by those conventional optimization techniques, and disadvantages of the conventional block theory are overcome. After some typical examples are tested, the stability of the left bank rock slope of Jinping-I Hydropower Station is conducted in detail, and the stability evolution due to excavation is systematically studied by this method.

Study on Control Technology of Slope in Mountainous Areas of Southwest China under Complex Geological Conditions

Deformation process of slope has been controlled by a variety of factors due to the unique geological, hydrological and meteorological conditions. And southwest mountain areas of China has been become high incidence areas of slope diseases during highway construction and operation. According to Wendu Road K55+590 ~ K55+670 left slope engineering geological environment, the deformation process and mechanism analysis, The key factor of the slope deforming destruction is proposed. the appropriate engineering treatments and the construction control measures are also proposed based on analysis.

A UWB pulse generation based on a phase modulator and programmable filter

A simple scheme for the ultra-wideband (UWB) pulse generation based on a phase modulator and programmable filter is proposed and experimentally demonstrated. By locating the center wavelength of two tunable lasers at left and right linear slope of the filter, polarity-reversed monocycle pluses are generated. A section of single mode fiber is utilized to introduce proper time delay between the pair of UWB monocycle pulses. By switching the programmable filter between bandpass filter and notch filter, positive and negative doublet pulse can be obtained additionally. The generated UWB pulses are measured in both time and frequency domain.

Structure formation in binary Al-TM (TM = Mn, Co, Ni, Cu) melts

The structures of binary Al-TM (transition metal TM = Mn, Co, Ni, Cu) melts at near-liquidus temperatures are studied by X-ray diffraction and simulation using the reverse Monte Carlo method. The melts are found to have chemical local atomic ordering, and this ordering depends on the nature and content of TM. Chemical local atomic ordering leads to a medium-range order as a result of TM atom localization at distances of 0.4–0.5 nm in the composition of polytetrahedral clusters having icosahedral symmetry. A medium-range order in the melts is identified due to the presence of an additional maximum (prepeak) in the left slope of the first peak in experimental structure factor curves. The local atomic orders in the melts and the corresponding crystalline and quasicrystalline phases are found to correlate with each other.

Comprehensive Stability Evaluation of Rock Slope Using the Cloud Model-Based Approach

This article presents the cloud model-based approach for comprehensive stability evaluation of complicated rock slopes of hydroelectric stations in mountainous area. This approach is based on membership cloud models which can account for randomness and fuzziness in slope stability evaluation. The slope stability is affected by various factors and each of which is ranked into five grades. The ranking factors are sorted into four categories. The ranking system of slope stability is introduced and then the membership cloud models are applied to analyze each ranking factor for generating cloud memberships. Afterwards, the obtained cloud memberships are synthesized with the factor weights given by experts for comprehensive stability evaluation of rock slopes. The proposed approach is used for the stability evaluation of the left abutment slope in Jinping 1 Hydropower Station. It is shown that the cloud model-based strategy can well consider the effects of each ranking factor and therefore is feasible and reliable for comprehensive stability evaluation of rock slopes.

Multifractal Analysis for Nutritional Assessment

The concept of multifractality is currently used to describe self-similar and complex scaling properties observed in numerous biological signals. Fractals are geometric objects or dynamic variations which exhibit some degree of similarity (irregularity) to the original object in a wide range of scales. This approach determines irregularity of biologic signal as an indicator of adaptability, the capability to respond to unpredictable stress, and health. In the present work, we propose the application of multifractal analysis of wavelet-transformed proton nuclear magnetic resonance (1H NMR) spectra of plasma to determine nutritional insufficiency. For validation of this method on 1H NMR signal of human plasma, standard deviation from classical statistical approach and Hurst exponent (H), left slope and partition function from multifractal analysis were extracted from 1H NMR spectra to test whether multifractal indices could discriminate healthy subjects from unhealthy, intensive care unit patients. After validation, the multifractal approach was applied to spectra of plasma from a modified crossover study of sulfur amino acid insufficiency and tested for associations with blood lipids. The results showed that standard deviation and H, but not left slope, were significantly different for sulfur amino acid sufficiency and insufficiency. Quadratic discriminant analysis of H, left slope and the partition function showed 78% overall classification accuracy according to sulfur amino acid status. Triglycerides and apolipoprotein C3 were significantly correlated with a multifractal model containing H, left slope, and standard deviation, and cholesterol and high-sensitivity C-reactive protein were significantly correlated to H. In conclusion, multifractal analysis of 1H NMR spectra provides a new approach to characterize nutritional status.

Sensor Network Optimal Design of Microseismic Monitoring System at the Left Slope of Jinping I Hydropower Station

In order to real time monitor and analyze the rock fracturing due to continuous construction and consolidation at the left slope of Jinping I hydropower station, southwest of China, a microseismic monitoring system was conducted and an optimal design for the sensor arrays was investigated. The sensor array was designed on the basis of P method and Powell algorithm. The artificial fixed blasting tests were applied to adjust the positioning accuracy of the monitoring system. The results show that the location error of seismic source is less than 12 m in the scope of the sensor array, which demonstrates the monitoring system has high positioning g accuracy. The contour of source location shows that the location errors near the main tunnels at the left bank slope is below 6 m. Signals from 689 microseismic events with moment magnitude ranging from -2.1 to -0.2 were recorded during the first year monitoring period from June 15, 2009. The spatial distribution of microseismicity can identify and delineate the potential failure at the left bank slope, which provides some references for the future excavation and consolidation of the hydropower station.

Analysis of left ventricular mass in untreated men and in men treated with agalsidase-β: data from the Fabry Registry

The aim of this study was to evaluate the progression of left ventricular hypertrophy in untreated men with Fabry disease and to assess the effects of agalsidase-β (recombinant human α-galactosidase A) on left ventricular hypertrophy. Longitudinal Fabry Registry data were analyzed from 115 men treated with agalsidase-β (1 mg/kg/2 weeks) and 48 untreated men. Measurements included baseline left-ventricular mass and at least one additional left-ventricular mass assessment over ≥ 2 years. Patients were grouped into quartiles, based on left-ventricular mass slopes. Multivariate logistic regression analyses identified factors associated with left ventricular hypertrophy progression. For men in whom treatment was initiated at the age of 18 to <30 years, mean left ventricular mass slope was -3.6 g/year (n = 31) compared with +9.5 g/year in untreated men of that age (n = 15) (P < 0.0001). Untreated men had a 3.4-fold higher risk of having faster increases in left-ventricular mass compared with treated men (odds ratio: 3.43; 95% confidence interval: 1.05-11.22; P = 0.0415). A baseline age of ≥ 40 years was also associated with left--ventricular hypertrophy progression (odds ratio: 5.03; 95% confidence interval: 1.03-24.49; P = 0.0457) compared with men younger than 30 years. Agalsidase-β treatment for ≥2 years may improve or stabilize left-ventricular mass in men with Fabry disease. Further investigations may determine whether early intervention and stabilization of LVM are correlated with clinical outcomes.

The Dynamic Evaluation of Rock Slope Stability Considering the Effects of Microseismic Damage

A state-of-the-art microseismic monitoring system has been implemented at the left bank slope of the Jinping first stage hydropower station since June 2009. The main objectives are to ensure slope safety under continuous excavation at the left slope, and, very recently, the safety of the concrete arch dam. The safety of the excavated slope is investigated through the development of fast and accurate real-time event location techniques aimed at assessing the evolution and migration of the seismic activity, as well as through the development of prediction capabilities for rock slope instability. Myriads of seismic events at the slope have been recorded by the microseismic monitoring system. Regions of damaged rock mass have been identified and delineated on the basis of the tempo-spatial distribution analysis of microseismic activity during the periods of excavation and consolidation grouting. However, how to effectively utilize the abundant microseismic data in order to quantify the stability of the slope remains a challenge. In this paper, a rock mass damage evolutional model based on microseismic data is proposed, combined with a 3D finite element method (FEM) model for feedback analysis of the left bank slope stability. The model elements with microseismic damage are interrogated and the deteriorated mechanical parameters determined accordingly. The relationship between microseismic activities induced by rock mass damage during slope instability, strength degradation, and dynamic instability of the slope are explored, and the slope stability is quantitatively evaluated. The results indicate that a constitutive relation considering microseismic damage is concordant with the simulation results and the influence of rock mass damage can be allowed for its feedback analysis of 3D slope stability. In addition, the safety coefficient of the rock slope considering microseismic damage is reduced by a value of 0.11, in comparison to the virgin rock slope model. Our results demonstrate that microseismic activity induced by construction disturbance only slightly affects the stability of the slope. The proposed feedback analysis technique provides a novel method for dynamically assessing rock slope stability and can be used to assess the slope stability of other similar rock slopes.

Soil and terrain favorability for grape-vine of a stagnic luvosoil from Cândeşti Piedmont, Ştefăneşti-Marcea Plateau.

Stefanesti township from Arges county is one of the most ancient and significant Romanian wine-growing regions. The wines created here have won local and world-wide appreciation. Plantations are placed both on the left slope of Arges river, where ample terrace systems and anti-erosional works have been performed, and on the piedmontan plateaus with clayey, vertic soils. The Arges County Soil Research Office has conducted a special soil survey research on Marcea piedmontan plateau in the summer of 2012. Consequently, a soil-profile was dig and the taken samples were analyzed in OSPA’s laboratory. The soil-profile is typical for most surface of the piedmontan relief and is placed within an entirely weedy plantation. Following the local examination and analytic interpretation, it results that soil’s taxonomy is stagnic aric Luvosol (Romanian Soil Taxonomy), resulting from a native stagnic Luvosol. Following the analysis of the main indicators regarding the soil-terrain system typical of the Stefanesti Plateau, Marcea zone belongs to the 4th pretability class and to the third quality class. Main soil restrictions are acidity and the clayish texture. Because a system of improvement works can be emplaced, the soil has been evaluated and after an improvement of the natural coefficients. In these terms, the soil crossed into the third class of quality and remains in the same class of pretability for vineyard plantation. The paper shows that the studied area gathers most of the conditions needed for capitalization of lands through conversion and expansion of vineyard plantations.

Research on the Sensitivity of Rock Slope Stability to the Effect Factors under Blasting Disturbance

The rock slope stability under blasting excavation disturbance is an important study content in the fields of hydropower, mining, transportation and other research field. Basing on a potential slip rock mass of the left slope of Jinping-Ⅰ Hydropower Station, using Sarma method of the limit equilibrium analysis and orthogonal experimental design, the paper analyzed the main factors which affect the slope stability, and studied the sensibilities of the slope stability to various factors under blasting disturbance. The results indicate that the slope stability under blasting disturb is very sensitive to the change of internal correlative of potential slip rock mass. The slope stability under blasting disturb is less sensitive to the change of external correlative factors which are result from the blasting.

Reduced corticomotor excitability and motor skills development in children born preterm

The mechanisms underlying the altered neurodevelopment commonly experienced by children born preterm, but without brain lesions, remain unknown. While individuals born the earliest are at most risk, late preterm children also experience significant motor, cognitive and behavioural dysfunction from school age, and reduced income and educational attainment in adulthood. We used transcranial magnetic stimulation and functional assessments to examine corticomotor development in 151 children without cerebral palsy, aged 10-13 years and born after gestations of 25-41 completed weeks. We hypothesized that motor cortex and corticospinal development are altered in preterm children, which underpins at least some of their motor dysfunction. We report for the first time that every week of reduced gestation is associated with a reduction in corticomotor excitability that remains evident in late childhood. This reduced excitability was associated with poorer motor skill development, particularly manual dexterity. However, child adiposity, sex and socio-economic factors regarding the child's home environment soon after birth were also powerful influences on development of motor skills. Preterm birth was also associated with reduced left hemisphere lateralization, but without increasing the likelihood of being left handed per se. These corticomotor findings have implications for normal motor development, but also raise questions regarding possible longer term consequences of preterm birth on motor function.

Unilateral bony ankylosis of the temporomandibular joint in a case of ankylosing spondylitis

Ankylosing spondylitis (AS) is a chronic inflammatory disease with multiple articular and para-articular involvement that has a predilection for the axial skeleton. In spite of its high prevalence, ankylosis secondary to AS is a rare condition. A 31-year-old male diagnosed with AS was referred for computed tomography (CT) of the temporomandibular joint (TMJ) due to severe mouth opening limitation. The patient had a 16-year medical history of AS and sought assistance due to TMJ pain and incapacity to open his mouth. Previous bony scintigraphy revealed involvement of the spine, sacroiliac joints, right knee, and left TMJ. Magnetic resonance imaging revealed erosion of the left condyle and posterior slope of the articular eminence, and a mass of heterogeneous signal intensity between these structures. The left condyle also presented sclerosis/edema of the bone marrow and the disk could not be identified. Sagittal and coronal CT images showed moderate alterations of the TMJ on the right side. On the left side, the images displayed markedly eroded condyle and mandibular fossa, and a bony mass resulting in ankylosis of the osseous components of the joint. TMJ ankylosis in AS patients is rare and very few reports have presented imaging features of the condition through advanced diagnostic techniques.

Stepwise Regression Arithmetic and its Application on Slope Safety Monitoring

Considering the effect of time, rainfall and temperature on slope deformation, deformation factors and expressions were deeply analyzed. Statistical regression model of slope deformation was established by Matlab software and stepwise regression algorithm, thus slope deformation can be regression analyzed and predicted. Through analyzing the deformation monitoring data of a hydropower station spillway left high slope, the result showed that statistical regression values of slope deformation are in good agreement with measured values, multiple correlation coefficients were good and the residual standard deviations were small. This model can reflect slope deformation and trend. It provided guidelines to analyze on security status and prediction of deformation trend with great practical value.