基于渗流实验的三轴流固耦合离散元数值模拟研究

卸压开采覆岩的应力场、裂隙场及渗流场耦合特性直接影响卸压瓦斯的运移特征。本文根据弹性煤样及贯穿裂隙煤样的应力渗流实验数据,结合渗流立方定律提出了数值模型中裂隙煤岩体流固耦合参数的选取方法,建立了三轴加载流固耦合数值模型。在此基础上模拟分析了单轴及三轴加载过程中煤样应力、裂隙及渗流的耦合特性。模拟结果表明:煤样渗透率随着轴向应变的升高呈S形变化,在煤样内部裂隙产生前随着轴压的增加而逐渐减小;煤样内部裂隙的产生及扩张使得渗透率开始升高,且裂隙扩张速度越快渗透率升高幅度越大;围压的升高使得煤样内部裂隙产生及扩展速度减缓,致使渗透率降低阶段延长,煤样初始渗透率及屈服后的渗透率逐渐减小。

Automatic Voltage Regulator Test of Three Gorges Right Bank Hydropower Station

Based on real-time digital simulations(RTDS),a laboratory environment similar to the real-time operation situation of the Three Gorges Hydropower Station is established.Then,the causes for the power fluctuation of the second generator by errors in the rotor rotating speed calculation are found,and the tuning method of the speed related parameters are given.The damping and reverse tuning characteristics of power system stabilizers(PSSs)in the digital automatic voltage regulator(AVR)are compared and investigated in the frequency range of 0.18-1.1 Hz.The efficiency of the proposed tuning method for ensuring power system stability is verified by RTDS.Finally,field tests show the validity of the laboratory test results.

A simplified testing method for stress-induced of tunnel surrounding rock

A simple testing method for secondary or induced stress of surrounding rockwas presented by laboratory experiment, numerical simulation and in situ testing based onthe basic principle of the historical stress restoring method.First, stress equivalent coefficient,which key coefficient of stress restored testing, was obtained by laboratory experiment.Second, experimental results were examined using 3D finite element numericalanalysis and the influence factors were analyzed by 2D finite element numerical analysis.The correctness of induced stress measuring results in situ for highway tunnel wereproved by elastic mechanics theory solution and single-hole stress rescission method.Thenew simple method of induced stress measuring has important practical value for undergroundengineering induced stress field analysis.

Diagnosis of Hypophosphatasia

Objective： HPP （Hypophosphatasia） is a congenital disease characterized by a deficiency of tissue-specific ALP （alkaline phosphatase）, which causes the generation of abnormal bone and tooth tissue. The clinical manifestations are variable, from neonatal forms with high mortality to milder adult forms with fractures and osteomalacia. The present study reports a clinical case of HPP, with emphasis on the physical characteristics and laboratory tests. The patient was attended at the medical genetics outpatient clinic of the Association of Parents and Friends of the Exceptional of Manaus （Associa？？o de Pais e Amigos dos Excepcionais-APAE/Manaus）. Methodology： For the case report, anamnesis, peripheral blood G-band karyotyping, Vitamin and ALP dosage and resonance examination were performed. Results： A.M.M.S, 9 years, non-consanguineous parents, no bone disease in the family, with one sister from the mother. Birth weight AGA without intercurrence. The patient presented a slight delay in psycho-motor development and was diagnosed with craniostenosis through CNS imaging examination. The physical examination, in addition to a short stature, showed dolichocephaly, frontal bossing, curved tibias and great dental compromise with many early cavities and loss of teeth. Laboratory evaluation： ALP dosage： 63/L （N = 69-325）; Vitamin B6 dosage： 27.4 （5.2-34.1）. The mother and the younger sister also had an ALP result below that expected for the age. Conclusions： The clinical phenotype and laboratory diagnosis of the patient were compatible with ICD Q78 HPP.

Massive Pericardial Effusion as the First Manifestation of Hypothyroidism in a Male Patient

This article intends to report a rare case of massive pericardial effusion as the first manifestation of hypothyroidism. A 45-year-old male patient, accompanied by a cardiology department, suddenly started to present signs of dyspnea and tiredness. He was submitted to an echocardiogram and diagnosed with dilated cardiomyopathy associated with a moderate pericardial effusion and low ejection of fraction. The laboratory tests showed elevated TSH levels （13.20 mIU/L）, what leads to the hypothyroidism diagnose and enable to start the treatment with levothyroxine. The patient has not followed correctly the treatment, reason why he has not showed any improves. He was admitted in the hospital to cardiology monitoring and the chest radiography confirmed an intense pericardial effusion. Then, the patient was submitted to the pericardiocentesis procedure, which was capable of remove the pericardial fluid for laboratory analysis and fragment of the pericardial sac for neoplastic cell research. After the hospital discharge, he was maintained in outpatient follow-up, when showed an important improvement in the clinical state.

Research on effect of clogging process on permeability of loose dam foundation of plateau reservoir

Taking Zhuoyu reservoir in Shannan of Tibet as the test site,the authors collected soil samples for laboratory analysis,and devised infiltration-clogging equipment for laboratory test to research the effect of clogging process on permeability of loose dam foundation of plateau reservoir.Through laboratory test,the soil can cause clogging effect by itself,and the effect of clogging is relative to the water pressure.The clogging effect can be caused obviously by adding fine particles,and the clogging effect of the particles with 0.063-0.25 mm diameter is best,which verifies the rationality of the optimal diameter interval.It provides the realistic significance for the anti-seepage of the plateau reservoir dam foundation.

Wind-power estimating model based on the experimental data in laboratory

Wind-power （WP） estimation is necessary for power system in several operations, which are as the optimal power flow between conventional units and wind farms, generators scheduling, and electricity market bidding. Estimating the output power of a wind energy conversion unit （WEC） mainly bases on the incident wind speed at the unit site by using the power characteristic curve. In addition, several time-series models have been using in wind speed forecasting. These models are characterized with requiring a large set of data. In order to prevent from the wind speed measurement and the need of a precise wind turbine model, an novel method basing on neural network and the grey predictor model GM （1,1） is proposed. Though the method, the estimating model can be built only by using the experimental data, which are obtained from the WP system in laboratory. The effectiveness of the estimating model is confirmed by the simulation results.

Experimental Evaluation of Rogowski Coil Performance for Locating PD in Energized Overhead Covered-Conductor Feeder

An experimental analysis is performed to evaluate Rogowski coil performance for PD （partial discharge） location on overhead CC （covered-conductor） distribution lines. The measuring set-up is arranged in high voltage laboratory. A multi-end measuring method is chosen as a technique to locate PD source point on the line. A power transformer is used to energize one end of the CC line by the AC voltage source. The performance of Rogowski-coil is tested in noisy environment. The tests are carried out conceming different measurement conditions such as off-line and on-line PD measuring systems. The results obtained from the laboratory measurements confirm the capability of the Rogowski-coil in order to measure and locate the high frequency PD source on the CC line in consistent with energizing AC source. Chirp detector is used as a signal-processing tool in order to extract the PD signals and then apply the locator algorithm.

Color change in a marine isopod is adaptive in reducing predation

Although background matching is a common form of camouflage across a wide diversity of animals, there has been surprisingly little experimental work testing the fitness consequences of this camouflage strategy, especially in marine ecosystems. In this study, we tested whether color camouflage enhances survival of the intertidal marine isopod Pentidotea （Idotea） wosnesenskii, quantified patterns of camouflage in different algal habitats, and examined how algal diet affected color change and growth using laboratory assays. In the field, isopods collected from two differently colored algal habitats （the brown alga Fucus distichus and the red alga Odonthaliafloccosa） matched the color of their respective algal habitats, and also differed significantly in body size： smaller red isopods were found on red algae, while larger brown isopods were found on brown algae. Predation ex- periments demonstrated these color differences had fitness benefits： brown isopods that matched their brown algae habitats sur- vived at higher rates than red unmatched isopods. Surprisingly, despite the propensity of isopods to match their algal habitats, algal diet had no effect on color change in color change experiments. Instead, isopods in all treatments turned browner, matching the color of the algal habitat that many isopods are found on as adults. In summary, our data supported our hypothesis that back- ground matching serves an adaptive function in reducing predation, with important evolutionary implications for explaining the wide variation in color change mechanisms in idoteid isopods [Current Zoology 61 （4）： 739-748, 2015].

Measurement of the applanated diameter of ocular cornea using a novel optical probe

A precise measurement of the applanated diameter of the ocular cornea with the optical probe is very important in applanation tonometry.A novel optical probe with a common path configuration is presented.The optical probe mainly consists of a cone-shaped prism and a photodetector.The former serves as a measuring body touching the ocular cornea to shape the area to be measured,and the latter converts the quantity of the luminous flux returning from the cone-shaped prism into one electronic current signal.Laboratory experiments are carried out on a simulated eyeball,followed by an enucleated porcine eyeball specimen.Experimental results show that there is a significant rise of the normalized variational current with increasing the applanation diameter of the ocular cornea,and the sensitivity is 0.2111/mm with an error of 0.00263/mm.Measurements of the normalized variational current on the porcine eyeball have good agreement with those on the simulated eyeball.

Electrical conductivity of hydrous silicate melts and aqueous fluids: Measurement and applications

The combination of magnetotelluric survey and laboratory measurements of electrical conductivity is a powerful approach for exploring the conditions of Earth's deep interior. Electrical conductivity of hydrous silicate melts and aqueous fluids is sensitive to composition, temperature, and pressure, making it useful for understanding partial melting and fluid activity at great depths. This study presents a review on the experimental studies of electrical conductivity of silicate melts and aqueous fluids, and introduces some important applications of experimental results. For silicate melts, electrical conductivity increases with increasing temperature but decreases with pressure. With a similar Na^+ concentration, along the calc-alkaline series electrical conductivity generally increases from basaltic to rhyolitic melt, accompanied by a decreasing activation enthalpy. Electrical conductivity of silicate melts is strongly enhanced with the incorporation of water due to promoted cation mobility. For aqueous fluids, research is focused on dilute electrolyte solutions. Electrical conductivity typically first increases and then decreases with increasing temperature, and increases with pressure before approaching a plateau value. The dissociation constant of electrolyte can be derived from conductivity data. To develop generally applicable quantitative models of electrical conductivity of melt/fluid addressing the dependences on temperature, pressure, and composition, it requires more electrical conductivity measurements of representative systems to be implemented in an extensive P-T range using up-to-date methods.