Experiment study on the law of effective stress of coal masses during methane drainage

The methane drainage can not only make coal seams deformation, but also effect its stress distribution. Based on lab experiment on methane drainage with a cubic coal sample of 500 mm×500 mm×500 mm, mutative law of coal of pore pressure （p） and effective stress （σef）i were investigated during methane drainage with the coal sample of China Lu＇an coal field No.3 coal seam. The experiment results indicate： during methane drainage pore pressure （p） follows exponential attenuation law： p=aexp（-bt）; effective stress （σef）i of coal masses follows logarithm incremental law： （σef）,=aln t＋b, （i=x, y, z）; effective stress coefficient（a） follows logarithm attenuation law： a=a-bln t; effective stress coefficient, volume stress （Θef） and pore pressure （p） follow bilinear law.

Recent progresses in the development of tubular segmented-in-series solid oxide fuel cells:Experimental and numerical study

Solid oxide fuel cells(SOFCs)have attracted a great deal of interest because they have the highest efficiency without using any noble metal as catalysts among all the fuel cell technologies.However,traditional SOFCs suffer from having a higher volume,current leakage,complex connections,and difficulty in gas sealing.To solve these problems,Rolls-Royce has fabricated a simple design by stacking cells in series on an insulating porous support,resulting in the tubular segmented-in-series solid oxide fuel cells(SIS-SOFCs),which achieved higher output voltage.This work systematically reviews recent advances in the structures,preparation methods,perform-ances,and stability of tubular SIS-SOFCs in experimental and numerical studies.Finally,the challenges and future development of tubular SIS-SOFCs are also discussed.The findings of this work can help guide the direction and inspire innovation of future development in this field.

Theoretical and Experimental Study on the Performance of Hermetic Diaphragm Squeeze Film Dampers for Gas-Lubricated Bearings

Low damping characteristics have always been a key sticking points in the development of gas bearings.The application of squeeze film dampers can significantly improve the damping performance of gas lubricated bearings.This paper proposed a novel hermetic diaphragm squeeze film damper(HDSFD)for oil-free turbomachinery supported by gas lubricated bearings.Several types of HDSFDs with symmetrical structure were proposed for good damping performance.By considering the compressibility of the damper fluid,based on hydraulic fluid mechanics theory,a dynamic model of HDSFDs under medium is proposed,which successfully reflects the frequency dependence of force coefficients.Based on the dynamic model,the effects of damper fluid viscosity,bulk modulus of damper fluid,thickness of damper fluid film and plunger thickness on the dynamic stiffness and damping of HDSFDs were analyzed.An experimental test rig was assembled and series of experimental studies on HDSFDs were conducted.The damper fluid transverse flow is added to the existing HDSFD concept,which aims to make the dynamic force coefficients independent of frequency.Although the force coefficient is still frequency dependent,the damping coefficient at high frequency excitation with damper fluid supply twice as that without damper fluid supply.The results serve as a benchmark for the calibration of analytical tools under development.

Experimental Study of Heat Transfer in an Insulated Local Heated fromBelow and Comparison with Simulation by Lattice Boltzmann Method

In this paper,experimental and numerical studies of heat transfer in a test local of side H=0.8 m heated from below are presented and compared.All the walls,the rest of the floor and the ceiling are made from plywood and polystyrene in sandwich form(3 mmplywood-3 cm polystyrene-3 mmplywood)just on one of the vertical walls contained a glazed door(2 H/3×0.15 m).This local is heated during two heating cycles by a square plate of iron the width L=0.6 H,which represents the heat source,its temperature Th is controlled.The plate is heated for two cycles by an adjustable set-point heat source placed just down the center of it.For each cycle,the heat source is switched“on”for 6 h and switched“off”for 6 h.The outdoor air temperature is kept constant at a low temperature Tc<Th.All measurements are carried out with k-type thermocouples and with flux meters.Results will be qualitatively presented for two cycles of heating in terms of temperatures and heat flux densitiesϕfor various positions of the test local.The temperature evolution of the center and the profile of the temperature along the vertical centerline are compared by two dimensions simulation using the lattice Boltzmann method.The comparison shows a good agreement with a difference that does not exceed±1℃.

Experimental study on box shape steel reinforced concrete beam

Experimental study on the fundamental behavior of box shape steel reinforced concrete （SRC） beams was conducted. Seven 1 ： 3 scale model SRC beams were tested to failure. The experimental results indicate that the flexural strength increases with the increase of the ratio of flexural reinforcement and the thickness of flange of the shape steel; the shear strength increases with the increase in the thickness of the web of the shape steel. Concrete filled in the box shape steel can prevent the early failure of specimens due to the buckling of the box shape steel, and increase the ultimate load. Measures should be made to strengthen the connection and co-work between the shape steel and the concrete. Formulae for flexural and shear strength of the composite beams are proposed, and the calculated results are in good agreement with the experimental results. In general, the box shape SRC beam is a kind of ductile member, and it is suitable for extensive engineering application.

EXPERIMENT STUDY ON THE EFFECT OF SHENG-MAI INJECTION ON THE CONTRACTIVITY OF DIAPHRAGM AND ITS MECHANISM

In this study the effect of Sheng-ai Injection i.e. Red Ginseng-Ophiopogon Root Injection (one kind of traditional Chinese medicines) on the contractivity of diaphragm was observed. The results confirmed that Sheng-ai Injection increased Pdi of the fatigued diaphragm in rabbits and reduced the time needed for the recovery of Pdi of fatigued diaphragm to the normal value. These results suggest that Sheng-Mai Injection can increase the contractive force and promote the recovery of the fatigued diaphragm. The effect of Sheng-ai Injection on the contractivity of the isolated diaphragmatic bundle of rats was also observed and the results confirmed that Sheng-ai Injection increased the diaphragmatic contractive force directly. This effect of increasing the contractive force of diaphragm was attenuated by adding calcium channel blocker isoptin and disappeared when there was no calcium in the extracellular fluid. It is deduced, therefore, that the mechanism of the effect of Sheng-mai Injection is related to the increased influx of calcium from extracellular fluid into the cells.

Experimental study on seismic behavior of semi-rigid connection between steel beam and concrete wall

Beam-column or beam-wall connections are an important problem in high-rise buildings. In this study, based on the analysis of an example structure, an analytical model for design of the semi-rigid connections between steel beams and RC walls in high-rise hybrid buildings is proposed. Also, the mechanical characteristics of these connections subjected to low-reversed cyclic loading are investigated through comparison of experimental results from three semi-rigid connections and two rigid connections. Moreover, some latent problems for design of these connections as well as the corresponding solutions are discussed. The results from the experiments and analyses indicate that semi-rigid connections exhibit satisfactory capacity and seismic performance, and the proposed design can be used in practice.

An experimental study on temperature increasing mechanism of satellitic thermo-infrared

Mixed gases (CO 2 and CH 4 etc .) in different ratio under the action of transient electric field may cause temperature to increase about 6℃, while under that of solar irradiation may lead temperature to rise around 3℃. The temperature increasing mechanism of satellitic thermo infrared of lower air is explained here based on an experimental study: thermo infrared temperature increasing of lower atmosphere may be caused by paroxysmal releasing of crustal gas and sudden changing of lower atmosphere electrostatic field. Therefore, appearance of the anomaly of thermo infrared temperature increasing prior to a moderate strong earthquake requires the concurrence of gas paroxysmal releasing and electrostatic field sudden changing at the same time.

Experimental study on full-scale steel beam-to-column moment connections

Ten full-scale steel beam-to-column moment connections used in moment-resisting frames （MRFs） were tested to study the failure process, failure mode, strength and plastic rotation capacity. The specimens include one traditional welded flange-bolted web connection, one traditional fully welded connection, four beam flange strengthened connections, three beam flange weakened connections, and one through-diaphragm connection. The test results show that the connections with flange cover plates or with partly cut beam flanges satisfy the beam plastic rotation demand for ductile MRFs. From the measured stress profiles along the beam flange and beam web depth, the mechanics of brittle fracture at the end of the beam is discussed. Design recommendations for steel beam-to-column moment connections are proposed.

Experimental Study on the Treatment of Tertiary Oil Recovery Wastewater via a Novel Electro-Coagulation Method

At present,methods for treating tertiary oil recovery wastewater via electro-coagulation are still in their early stage of development.In this study,a device for electro-coagulation wastewater treatment was built and tested in an oil field.The effects that the initial pH value,electrode type,and connection mode have on the coagulation and separation effect were assessed by measuring the mass fraction and turbidity of oil.The results have shown that when the electro-coagulation method is used,the effectiveness of the treatment can be significantly increased in neutral pH conditions(pH=7),in acidic conditions,and in alkaline conditions.Compared to an Al electrode,the floc that is produced by an Fe electrode is smaller;thus,it does not easily coagulate and settle in a short time.Using the oil removal rate,turbidity removal rate and energy consumption as a basis to assess the performances,the results have demonstrated that the combined aluminum alloy iron composite electrode should be used as electrolytic electrode.

Experimental and Numerical Study of Wave-Induced Long-Shore Currents on A Mild Slope Beach

The long-shore current distribution on a mild slope beach is studied by combining the numerical model and the physical experiment. The experiments of long-shore currents under the action of regular and irregular waves are conducted on mild beaches with different slopes in a wave basin. A numerical model is established, which includes a wave propagation model, a wave breaking model and a long-shore current model. The validity of the numerical model is proved by the comparison of its results with the results of the experimental model. It is concluded that the wave-ioduced long-shore current is influenced significantly by the incident wave height, the wave angle and the beach slope. Its application to the Bohai Bay indicates that the wave-induced currents have the same order of magnitude as the tide currents in the near-shore zone of mill slope beach. In the design of wastewater ouffall locations on a mild-slope beach with shallow water of the Bohai Bay, the position of the outfall should be 10 km away from the shoreline, which is outside of the surf-zone.

Effects of Perforated Baffle on Reducing Sloshing in Rectangular Tank:Experimental and Numerical Study

A liquid sloshing experimental rig driven by a wave-maker is designed and built to study liquid sloshing problems in a rectangular liquid tank with perforated baffle. A series of experiments are conducted in this experimental rig to estimate the free surface fluctuation and pressure distribution by changing external excitation frequency of the shaking table. An in-house CFD code is also used in this study to simulate the liquid sloshing in three-dimensional （3D） rectangular tank with perforated baffle. Good agreements of free surface elevation and pressure between the numerical results and the experimental data are obtained and presented. Spectral analysis of the time history of free surface elevation is conducted by using the fast Fourier transformation.

Simulation Analysis and Experimental Study of Defect Detection Underwater by ACFM Probe

This article studies the application of the alternating current field measurement （ACFM） method in defect detection for underwater structures. Numerical model of the ACFM system is built for structure surface defect detection in seawater environment. Finite element simulation is performed to investigate rules and characteristics of the electromagnetic signal distribution in the defected area. In respect of the simulation results, underwater artificial crack detection experiments are designed and conducted for the ACFM system. The experiment results show that the ACFM system can detect cracks in underwater structures and the detection accuracy is higher than 85%. This can meet the engineering requirement of underwater structure defect detection. The results in this article can be applied to establish technical foundation for the optimization and development of ACFM based underwater structure defects detection system.

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.

Experimental Study on Characteristics of NiMnGa Magnetically Controlled Shape Memory Alloy

The static and dynamic magnetic controlling characteristics of NiMnGa magnetically controlled shape memory alloy （MSMA） were experimentally studied. The results show that the characteristics of induced strain with respect to the magnetic field are nonlinear with saturation nature, and dependent on the temperature as well as the load applied to the MSMA. The magnetic shape memory effect can be observed only in complete martensite phase at room temperature. The magnetic permeability of MSMA is not constant and reduces with the increment of magnetic field. The relative saturation magnetic permeability of MSMA is about 1.5.

Experimental Study on the Aerodynamic Performance of Swept-Curved Blade

Compared with a straight blade, a unique compressor blade integratedforward-swept and positive-curved stacking line is studied experimentally. Aerodynamic parameters ofthe two cascades are measured by a five-hole probe at different positions and ink trace flowvisualization is conducted on blade surfaces. The result shows that the swept-curved cascade haslower endwall loss and higher midspan loss as compared with the straight cascade. However, lowerloss is accompanied with lower diffusion factor. Opposite 'C' shape static pressure distribution isestablished on the suction surface of the swept-curved blade, which is helpful for avoiding theaccumulation of low energy fluid in the endwall corner region. Anyhow the studies support theconclusion that the swept-curved blade conduces to not only the reduction of overall loss but alsothe improvement of stable operation in the endwall corner region.

Design and Experimental Study of an 80C196KC-Based SRD System Controller

Aim To design and experimentally study an 80C196KC-based SRD (switched re- luctance motor drive drive sytem) controller,Methods with the guidelines of the digitized SRD system controller,the circuit design and software programming were completed,and a relevantexperimental system was PUT forward to test the newly designed controller.Result The experi-mental study showed that the newlydesigned controller had good speed-adjusting characteristicfor a switched reluctance motor ,its stable error was less than 5% and its full-load startingtime was shorter than 1.8s .Conclusion The new controller has reasonable circuit design and suitable controlling algorithm,and it is a feasible SRD system controller design scheme.

Experimental study of destruction to porcine spleen in vivo by microwave ablation

AIM: To discuss the safety, feasibility and regularity of destruction to porcine spleen in vivo with congestion and tumescence by microwave ablation (MWA). METHODS: Ligation of the splenic vein was used to induce congestion and tumescence in vivo in five porcine spleens, and microwave ablation was performed 2-4 h later. A total of 56 ablation points were ablated and the ablation powers were 30-100 W. The ablation time (1, 2, 3, 4, 5, 6, 7, 8, 9 and 10 min) was performed at a power of 60 W. After ablation, the ablation size was measured in pigs A, C, D and E and spleen resection. In pig B, the ablation size was measuredand 2 ablation points were sent for pathology analysis and all tissues were sutured following ablation. Pig B was killed 1 wk later and the ablation points were sent for pathology analysis. Bleeding, tissue carbonization surrounding electrodes, and pathological changes were observed, and the effect on destruction volume relative to different ablation powers, times and positions was analyzed. RESULTS: The incidence of bleeding (only small amounts, < 20 mL) in the course of ablation was 5.4% (3/56) and was attributed to tissue carbonization surrounding electrodes, which also exhibited an incidence of 5.4% (3/56). The destruction volume was influenced by different ablation powers, times and points. It showed that the ablation lesion size increased with increased ablation time, from 1 to 10 min, when the ablation power was 60 W. Also, the ablation lesion size increased with the increase of ablation power, ranging from 30 to 100 W when the ablation time was set to 3 min. A direct correlation was seen between the destruction volume and ablation time by the power of 60 W (r = 0.97542, P < 0.0001, and also between the destruction volume and ablation powers at an ablation time of 3 min (r = 0.98258, P < 0.0001). The destruction volume of zone Ⅱ (the extra-2/3 part of the spleen, relative to the fi rst or second class vascular branches), which was near the hilum of the spleen, was noteably larger than the destruction volume of zoneⅠ(the intra-1/3 part of the spleen) which was distal from the hilum of the spleen (P = 0.0015). Pathological changes of ablation occurring immediately and 1 wk after MWA showed large areas of coagulation. Immediately following ablation, intact spleen tissues were observed in the areas of coagulation necrosis, mainly around arterioles, and there were no obvious signs of hydropsia and inflammation, while 1 wk following the ablation, the coagulation necrosis was well distributed and complete, as many nuclear fragmentations were detected, and there were obvious signs of hydropsia and inflammation.CONCLUSION: In vivo treatment of congestion and tumescence in the spleen using microwave ablation of water-cooled antenna is a safe and feasible method that is minimally invasive.

Experimental Study on Bubble Pulse Features Under the Combined Action of Horizontal and Vertical Walls

The pulse features of a bubble have a close connection with the boundary condition. When a bubble moves near a rigid wall, it will be attracted by the Bjerknes force of the wall, and a jet pointing at the wall will be generated. In real application, the bubble may move under the combined action of walls in different directions when it forms at the corner of a pipe or at the bottom of a dam. The motion of the bubble shows complex and nonlinear characteristics under these conditions. In order to investigate the bubble pulse features near complex walls, a horizontal wall and a vertical wall are put into the experimental water tank synchronously, and an electric circuit with 200 voltages is designed to generate discharge bubbles, and then experimental study on the bubble pulse features under the combined action of horizontal and vertical walls is carried out. The influences of the combined action of two walls on the bubble shape, pulse period, moving trace and inside jet are obtained by changing the distances from bubble center to the two walls. It aims at providing references for the relevant theoretical and numerical research.

Experimental study ofcasing wear under impact-sliding conditions

Theoretical analysis and field monitoring show that lateral vibration has very important effect on casing wear in deep & ultra-deep well drilling. The wear mechanism of casing under impact-sliding work conditions has been investigated and many experiments have been completed with a newly developed full-scale casing wear test machine. Test results present that adhesion wear, contact fatigue, and grinding abrasion are the main wear mechanisms under impact-sliding test conditions. The friction coefficient and linear wear rate of the casing rise obviously with an increase in impact load. And the larger the impact load, the rougher the worn surface of the casing. The linear wear rate decreased slightly but the average friction coefficient increased slightly with an increase in impact frequency under an impact load of 2,500 N. Both the linear wear rate of the casing and the average friction coefficient increased substantially with an increase in impact frequency under an impact load of 4,000 N. Under lower impact load conditions, grinding abrasion and contact fatigue are the main mechanisms of casing wear; under higher impact load conditions, adhesion wear and contact fatigue are the main mechanisms of casing wear.