Probabilistic approach for open pit bench slope stability analysis——A mine case study

The geotechnical slope design of an open pit wall starts at the bench scale configuration.At this scale,the rock slope stability is governed primarily by the geological discontinuities within the rock mass and as a result,structurally-controlled failures(e.g.planar,wedge or toppling)are most likely to occur.The probabilistic approach offers a major advantage over the traditional deterministic method in that it accounts for the different degrees of variability and uncertainty often encountered in rock properties.This paper presents a bench slope stability assessment for an open pit mine in Peru using a probabilistic-based approach by coupling a kinematic analysis based on stereographic projection techniques followed by a kinetic analysis by means of the limit equilibrium method.Finally,these two probabilities are combined to provide an overall measure of the probability of failure(PoF)of the bench slope system.The case study is characterized by significant scatter in the geometrical and mechanical properties of the joints.Extensive surface mapping was conducted at 36 different sites following the ISRM suggested procedures.Several direct shear tests were carried out.It is shown that by combining field and laboratory measurements and engineering judgment,the probability density functions(PDF)of the discontinuity parameters can be obtained.These are then used in a Monte Carlo simulation process to compute both kinematic and kinetic probabilities of failure.The overall probability of failure aims to provide the design engineer with a tool to critically evaluate the bench performance from a geotechnical risk perspective and to provide a basis for future bench design optimization.

Wheel-shaped icosanuclear Cu-containing polyoxometalate catalyst: Mechanistic and stability studies on light-driven hydrogen generation

In this paper,we report the synthesis and characterization of a wheel-shaped icosanuclear Cu-containing polyoxometalate(POM),K_(12)Li_(13)[Cu_(2)0Cl(OH)_(24)(H_(2)O)_(12)(P_(8)W_(48)O_(184))]·22H_(2)O(K_(12)Li_(13)-Cu_(2)0P_(8)W_(48)).The resulting cation-exchanged tetrabutylammonium salt of the polyoxoanion Cu_(2)0P_(8)W_(48)(TBA-Cu_(2)0P_(8)W_(48))exhibits high efficiency for visible-light-driven H_(2) production in the presence of an[Ir(ppy)2(dtbbpy)][PF_(6)]photosensitizer and a triethanolamine electron donor.Under optimal conditions,the turnover number for H_(2) production reaches~2892 after 5 h of photocatalysis and thereafter continuously increases to~13400 in a long-term 120 h reaction,representing the best performance among all reported transition-metal-substituted POM catalysts.Mechanistic studies confirm the existence of reductive and oxidative quenching processes,of which the reductive quenching pathway is dominant.Various stability tests demonstrate that the TBA-Cu_(2)0P_(8)W_(48) catalyst slowly dissociates Cu ions under turnover conditions;however,both the starting TBA-Cu_(2)0P_(8)W_(48) and its molecular decomposition products are dominant active species for efficient and long-term H_(2) production.

Positron Annihilation Study on the Microstructural Stability in Rapidly Solidified Al_(92.3)Fe_(4.3)V_(0.7)Si_(1.7)Mm_(1.0) Alloy

Rapidly solidified Al92.3Fe4.3V0.7Si1.7Mm1.0 alloy has been studied by positron lifetime spectroscopy and the variations on the intedecial defects with the annealing temperature were revealed by an analysis of the lifetime results. The intedece characteristics derived from the positron-lifetime results could be used to give a satisfactory interpretation of the dependence of mechanical properties on the annealing temperature

Stability of Hydroxytyrosol in Aqueous Solutions at Different Concentration, Temperature and with Different Ionic Content: A Study Using UPLC-MS

The work describes a stability study of hydroxytyrosol (HTyr) in aqueous solutions carried out varying the following parameters: HTyr concentration, temperature and ionic content in the aqueous solution. First, an analytical method based on the use of ultra performance liquid chromatography (UPLC-MS) as analytical technique was developed and validated. The equation of the linear model was A/AISTD= –0.0013 + 0.0117. [HTyr], with a very good linearity, since the R-Squared was 99.9% and the P value of the lack of fit test was higher than 5%. Limits of quantification estimated, CCα(α= 0.05%) and CCβ(β= 0.05%), were 0.2 and 0.4 g/L respectively. As well, the relative standard deviation in the intra-day precision was lower than 3%. Therefore, the method is reproducible. We have applied this methodology to study the stability of HTyr and have observed that the most critical aspect turned to be the ionic content of the aqueous solutions. A tap water with high contents of calcium and magnesium (52 and 21 mg/L) degraded HTyr up to 64% in 48 hours whereas a low mineralization water with low contents of calcium and magnesium (4 and 2 mg/L) produced only 19% degradation.

Determination of the Stability Studies of the Sudanese Camel Insulin

The main objective of the presented study was to characterize the stability of the Sudanese camel insulin after 6 months of its extraction, purification and formulation from the fresh pancreatic glands of the camel, slaughtered for local and export consumption. The stability and purity of the formulated insulin samples were compared to standard insulin sam-ples that of the leading manufacturing companies using some analytical techniques such as HPLC, gel electrophoresis and atomic absorption. In another part of the study, the direct transfer method was used to accomplish sterility test by complete immersion of the insulin samples into thioglycollate and soybean medium. The data were presented as mean ± S.E.M (standard error of means) for the comparison of zinc (mg/units) and nitrogen (in percentage) concentrations in standard and testing camel insulin samples, respectively. Similarly, the linear equation was derived and the coefficient factors for standard and testing insulin samples were compared to determine the peak area and the concentrations of the camel insulin samples (mean ± S.E.M) after HPLC elution. The P value,

Analytical and Stability Studies on Medical Cosmetics

Two simple and sensitive spectrofluorimetric (method Ι) and spectrophotometric (method ΙΙ) methods have been developed for the determination of some chloride containing toothpastes and panthenol-containing cosmetic preparations respectively. Method Ι is based on quantitative fluorescence quenching of (terbium-salicylate-hexamine ternary complex) by fluoride which could be measured at λem/λex of 547 nm/322 nm. The ΔF-concentration plot was rectilinear over the concentration range of 0.5 - 20 μg/ml. Method ΙΙ depends reaction of panthenol with nitrobenzoxadiazole chloride (NBD-Cl) and measuring the absorbance of the resultant product at 480 nm. The absorbance-concentration plot was rectilinear over the concentration range of 2 - 20 μg/ml.

Role of the posterior deep deltoid ligament in ankle fracture stability: A biomechanical cadaver study

BACKGROUND The deltoid ligament is a key component of ankle fracture stability.Clinical tests to assess deltoid ligament injury have low specificity.In supination externalrotation(SER)type-IV ankle fractures,there is either a medial malleolus fracture or deltoid ligament injury.These injuries are often considered unstable,requiring surgical stabilisation.We look to identify the anatomical basis for this instability.This study investigates the anatomical basis for such instability by re-creating SER type ankle fractures in a standardised cadaveric study model,investigating the anatomical basis for such instability.AIM To investigate the anatomical basis for fracture instability in SER type ankle fractures.METHODS Four matched pairs of cadaveric limbs were tested for stability both when axially loaded and under external rotation stress.Four matched pairs of cadaveric limbs(8 specimens)were tested for stability when axially loaded to 750 N with a custom rig.Specimens were tested through increasing stages of SER injury in a stepwise fashion before restoring the lateral side with open reduction and internal fixation(ORIF).Clinical photographs and radiographs were recorded at each step.We defined instability in accordance with well accepted radiological parameters:>4 mm medial clear space opening on a mortise-view radiograph or>7 degrees of talar tilt.RESULTS All specimens with an intact posterior deep deltoid ligament were stable.Once the posterior deep deltoid ligament was sectioned there was instability in all specimens.Stabilisation of the lateral side prevented talar shift,but not talar tilt.CONCLUSION If the posterior deep deltoid ligament is intact then SER fractures can be managed without surgery.If the posterior deep deltoid is incompetent,ORIF and cautious rehabilitation is recommended because the talus can still tilt in the mortise.

Stability Study of O/W Cosmetic Emulsions Using <i>Rosmarinus officinalis</i>and <i>Calendula officinalis</i>Extracts

Cosmetic emulsions, as all macro emulsions, are inherently unstable systems, from a thermodynamic viewpoint. More specific eco-friendly oil/water (O/W) cosmetic emulsions are usually less stable than conventional ones as milder chemicals or less intense (energy consuming) production processes are involved. In this context, two traditional techniques an optical technique and a volumetric one have been used for the assessment of the stability of cosmetic emulsions and compared to each other. Eco-friendly cosmetic emulsions were produced with different olive oil/water extracts (Rosmarinus officinalis and Calendula officinalis extracts) and emulsifier (Glycerol monostearate, GMS) concentrations. Emulsions’ stability was registered simultaneously by 1) Microscopy photos of samples withdrawn at regular intervals from the test vessel;2) global volumetric measurements of the different phases (water/oil/emulsion) inside the test vessel made at regular intervals for determining the evolution of the location of the phases separation interface. Analysis of the results of each technique and comparisons among them are presented and discussed in detail.

Formulation Development, in Vitro Evaluation and Stability Study of Aceclofenac Tablet

The objective of the study was to develop film coated tablets of aceclofenac using wet granulation technique. Possible drug-excipient interaction was evaluated by HPLC （high performance liquid chromatography） and FTIR （fourier infrared spectroscopy）. The tablets prepared were assessed for their physicochemical, in vitro dissolution at pH 1.2, 4.5, 6.8 and 7.5 and stability characteristics. Comparison with a commercial aceclofenac product was made in vitro and in vitro studies. There was no interaction between aceclofenac and used excipients. Furthermore, the physicochemical properties of the tablets were satisfactory. The dissolution profile of one of the formulated aceclofenac tablets （D07） was statistically similar （p 〈 0.05） to that of the commercial aceclofenac brand in all the dissolution media. The formulated products ware stable and showed no changes in physical appearance, drug content, or dissolution pattern after storage at 40 ℃/75% RH for 6 months. The results indicate that it is feasible to achieve a stable aceclofenac tablet formulation by using wet granulation technique.

Study on the Submarine Slope Stability of the Deep Channel in the Caofeidian Harbor

Objective The greatest advantage of the Caofeidian Harbor is its deep channel facing the Bohai Bay. The deep channel is a natural port hub for shipping of the Caofeidian Habor. The construction of the Caofeidian Harbor has impacted the hydrodynamic environment and the sediments movement, which has attracted much attention about the geomorphic evolution, slope stability and the evolution trend after submarine slope destruction. Insight from this study might be significant for the future development of the Caofeidian Habor, including planning, operation and maintenance.

STUDIES ON PROCESS AND STABILITY OF BONDED Sm_2TM_(17)MAGNETS WITH HIGH COERCIVITY AND HIGH ENERGY PRODUCT

The process of the epoxy-bonded Sm_2TM_(17) magnets includes:(1)after melting,the ingots are treated by solid soluiion,and then aged and pulverized;(2)the obtained alloy powder is mixed with epoxy resin bind- er;(3)the mixture is pressed in a magnetic field;(4)the compacts are cured.When the SmCo_(4.9)Fe_(2.7)Cu_(0.54)Zr_(0.13) alloy is heat treated and pressed with optimum pressing parameters,the high quality bonded magnets with B_r=8250 G,_iH_c=13000 Oe,and(BH)_(max)=16MGOe can be obtained.The stability of the magnets is studied also.The irreversible loss of O.C.(open circuit)remanence B_r in the temperature range between 25 and 150℃,is less than 4%.The average temperature coefficient at temperatures between 25 and 70℃ is-0.03%/℃.The magnets obtained have heat resistance up to 130℃ even in long-term service, and have good corrosion resistance in acid,alkali and salt solutions.

Engineering Geological Study of Regional Tectonic Stability in the Area of the Longyang Gorge Power Station on the Huanghe (Yellow) River

In the stability study of the regional structures in the area of the Longyang Gorge Hydroelectrical Power Station, a model of the current stress-deformation field of the area was constructed based on analyses of available data of regional surveys and historical earthquakes and field investigations of active faults and ancient earthquakes. This model was examined and verified by physical and mathematical simulation experiments, and quantitative relations and data were obtained.

STUDY ON THE STABILITY AND STACKING INTERACTION EFFECT OF THE TERNARY M(Ⅱ)(ATP)AND PYRIDINE-LIKE LIGANDS

The stabilities of the complexes of three pyridine-like ligands with M(II)(ATP)^(2-) and M(II)(M=Ni,Co)were studied by spectrophotometry and by comparing the stability constants of the ternary complexes with these of the binary complexes.A stacking interaction between the pyridine ring and the purine ring of ATP is indicated.The general existence of the stacking interaction encourages us to interpret the antitumor mechanism of a new class of antitumor drugs.

Production and stability study of a hospital parenteral nutrition solution for neonates

Standard parenteral nutrition solutions are mixtures comprising interacting components that may degrade themselves over time. The objective of this study was to investigate the physicochemical and microbiological stability of a hospital preparation for parenteral nutrition in neonatology. The analyses were performed throughout the storage of the preparations at 2–8 °C(up to 4 months). The extent of stability was based on the determination of amino acids dosage, visual and physicochemical properties(glucose and electrolytes concentrations, pH and osmolality measurements, particle counting) and microbiological analysis(sterility test). A thermal degradation of ascorbic acid was conducted to evaluate the antioxidant properties of the parenteral mixture. Physicochemical and microbiological controls were found to comply with the specifications. Amino acids showed a good stability throughout the 4 months storage except for cysteine, which was progressively degraded to cystine, conferring a yellow coloration to parenteral solutions. Parenteral nutrition standards solutions remain stable for 4 months at 2–8 °C,ensuring safe administration in preterm infants.

Studies on Early-warning System for Social Stability: Vital to China

As a large country in the world, it is both necessary and possible to develop and operate a pre-warning system for social stability, says Prof. Niu Wenyuan, chief scientist for strate-

A field experimental study of lignin sand stabilizing material(LSSM) extracted from spent-liquor of straw pulping paper mills

A new technique was introduced for sand stabilization and re-vegetation by use of lignin sand stabilizing material(LSSM). LSSM is a reconstructed organic compound with lignin as the most dominant component from the extracts of black-liquor issued by straw pulp paper mills. Unlike the polyvinyl acetate or foamed asphalt commonly used for dune stabilization, the new material is plant-friendly and can be used with virescence actions simultaneously. The field experimental study was conducted since 2001 in China's Northwest Ningxia Hui Autonomous Region and has been proved that LSSM is effective in stabilizing the fugitive dunes, making the arenaceous plants survive and the bare dune vegetative. The advisable solution concentration is 2% and the optimal field spraying quantity is 2 5 L/m^2 The soil nutrients of the stabilized and greened dune, such as organic matter, available phosphorous and total nitrogen are all increased compared with the control treatment, which is certainly helpful to the growth of arenaceous plants. The technique is worthwhile to be popularized because it is provided not only a new method for desertification control but also an outlet for cleaning contaminants issued from the straw paper mills.

Stability of boundary pillars in transition from open pit to underground mining

Based on the height of back-filled materials, thickness of ore body, height of boundary pillar and dipping angle of ore body and water pressure, the safety factors of all the pillars are calculated with the limit equilibrium method. The calculation results present that the safety factors of pillars in Sections 19, 20, 24, 28 are less than 1.3, and those of unstable sections are identified preliminarily. Further, a numerical investigation in Sections 18, 20, 22, 24, 25 and 28 implemented with numerical code RFPA20 is employed to further validate the pillar performance and the stability of stopes. The numerical results show the pillars in Sections 18, 22 and 24 are stable and the designed pillar size is suitable. The width of the ore body near Section 28 averages 20 m, failure occurs in the left stope, but the boundary pillars near Section 28 maintain good performance. The pillars in Sections 20 and 25 are unstable which are mainly affected by the Faults F8 and F18. The existence of faults alters the stress distribution, failure mode and water inrush pathway. This work provides a meaningful standard for boundary pillar and stope design in a mine as it transitions from an open pit to underground.

Investigation of factors influencing roof stability at a Western U.S.longwall coal mine

The coal mine roof rating(CMRR) was developed to bridge the gap between geological variation in underground coal mines and engineering design. The CMRR accounts for the compressive strength of the immediate roof, the shear strength and intensity of any discontinuities present, and the moisture sensitivity of the immediate roof. The CMRR has been widely used and validated in Eastern US coal mines, but it has seen limited application in the Western US. This study focuses on roof behavior at a Western coal mine(Mine A). Mine A shows significant lateral geological variation, along with localized faulting and a laterally extensive sandstone channel network. The CMRR is not used to predict roof instability at the mine. It is, therefore, hypothesized that there are other factors that are correlated with roof instability in underground coal mines that could potentially also be considered in conjunction with the CMRR.This hypothesis was tested by collecting 30 CMRR measurements at Mine A. At each measurement location, a binary record of the roof condition(stable or unstable) was made, and other parameters such as depth of cover, presence of faulting, and sandstone channels were also recorded. ANOVA tests showed that the CMRR values and the roof conditions were not strongly correlated, indicating that the CMRR input criteria are not fully predictive of roof stability at this mine. The CMRR values showed statistically significant correlations(p less than 0.05) with faulting as well as with location at an intersection. For areas that had previously experienced roof fall but were currently stable, faulting was correlated with roof condition(p less than 0.05) only when the condition was classified as unstable.

An Experimental Investigation on the Stability of Foundation of Composite Vertical Breakwaters

A series of 2D model tests were conducted to assess the foundation stability of composite vertical breakwaters. In this paper, the results from the experimental study are presented conjointly with a formula to estimate the stability number of foundation, which is the most important parameter for evaluation of foundation stability of such structures. The influences of wave height, wave period and the berm width on the stability of compo^ite breakwaters with different armor stone sizes were investigated. Forty-five tests were performed to cover the influences of these parameters. According to the present research, berm width is a significant parameter concerning erosion of armor foundation. As the berm width increases, the amount of berm erosion decreases. Comparisons are made between results of present study and the estimated stability number proposed by Kimura et al. （1994）, which is extension of Tanimoto formula. Results show that the later formula underestimates the stability number. However, by applying an enhancement factor about 1.7 meters to Kimura et al. formula, results correlated with the present experimental results..