漏入汽轮机真空系统空气量的软测量

针对目前汽轮机真空系统漏气量的直接测量一直没有好的方法的问题,文中提出一种基于真空系统严密性试验,并结合BP网络的漏入真空系统空气量的软测量方法。该方法以影响真空下降速度的凝汽器各运行参数以及真空下降速度作为网络的输入,以常规测量方法得到的漏入真空系统空气量作为目标输出,实现对漏入真空系统空气量的软测量。数值仿真结果证明该方法可以较准确地实现在真空系统严密性试验中对漏入真空系统空气量的测量。

Implementation of heat exchanger performance testing system of heat transfer and flow resistance

A heat transfer performance testing system is presented with its hardware structure, operation principle, and software control and measurement system. Working fluids of the subsystem include thermal conducting oil, compressed air, glycol water solution and water as the heating fluids, and air and water as the cooling fluids. The heat transfer performance testing of heat exchangers can be conducted not only for a conventional one heating fluid to one cooling fluid, but also for a compound air cooling heat exchanger with two or three heating fluids in parallel or in series. The control and measurement system is implemented based on a LabVIEW software platform, consisting of the data acquisition and process system, and the automotive operation and control system. By using advanced measuring instruments combined with sound computer software control, the testing system has characteristics of a compact structure, high accuracy, a wide range of testing scope and a friendly operation interface. The uncertainty of the total heat transfer coefficient K is less than 5%. The testing system provides a reliable performance testing platform for designing and developing new heat exchangers.

Experimental assessment of two-phase bubble pump for solar water heating

The research goal is to develop a new solar water heater system(SWHS) that uses a solar bubble pump instead of an electric pump.The pump is powered by the steam produced from an evacuated tube collector.Therefore,heat could be transferred downward from the collector to a hot water storage tank.The designed system consists of two sets of heat-pipe evacuated tube collectors,a solar bubble pump installed at an upper level and a water storage tank with a heat exchanger at a lower level.Discharge heads of 1 and 5 m were tested.The bubble pump could operate at the collector temperature of about 90-100 ℃ and vapor gage pressure of 80-90 kPa.It is found that water circulation within the SWHS depends on the incident solar intensity and system discharge head.Experimental investigations are conducted to obtain the system thermal efficiencies from the hourly,daily and long-term performance tests.The thermal performance of the proposed system is compared with conventional solar water heaters.The results show that the proposed system achieves system characteristic efficiency of 10% higher than that of the conventional systems using electric pump if taking the consumption of electric power into account.And the former is a zero carbon system.

Model test to investigate failure mechanism and loading characteristics of shallow-bias tunnels with small clear distance

Based on the similarity theory,a tunnel excavation simulation testing system under typical unsymmetrical loading conditions was established.Using this system,the failure mechanism of surrounding rock of shallow-bias tunnels with small clear distance was analyzed along with the load characteristics.The results show that:1) The failure process of surrounding rock of shallow-bias tunnels with small clear distance consists of structural and stratum deformation induced by tunnel excavation; Microfracture surfaces are formed in the tunnel surrounding rock and extend deep into the rock mass in a larger density; Tensile cracking occurs in shallow position on the deep-buried side,with shear slip in deep rock mass.In the meantime,rapid deformation and slip take place on the shallow-buried side until the surrounding rocks totally collapse.The production and development of micro-fracture surfaces in the tunnel surrounding rock and tensile cracking in the shallow position on the deep-buried side represent the key stages of failure.2) The final failure mode is featured by an inverted conical fracture with tunnel arch as its top and the slope at tunnel entrance slope as its bottom.The range of failure on the deep-buried side is significantly larger than that on the shallow-buried side.Such difference becomes more prominent with the increasing bias angle.What distinguishes it from the "linear fracture surface" model is that the model proposed has a larger fracture angle on the two sides.Moreover,the bottom of the fracture is located at the springing line of tunnel arch.3) The total vertical load increases with bias angle.Compared with the existing methods,the unsymmetrical loading effect in measurement is more prominent.At last,countermeasures are proposed according to the analysis results: during engineering process,1) The surrounding rock mass on the deep-buried side should be reinforced apart from the tunnel surrounding rock for shallow-buried tunnels with small clear distance; moreover,the scope of consolidation should go beyond the midline of tunnel(along the direction of the top of slope) by 4 excavation spans of single tunnel.2) It is necessary to modify the load value of shallow-bias tunnels with small clear distance.

Anti-inflammatory effect of cannabinoid agonist WIN55, 212 on mouse experimental colitis is related to inhibition of p38MAPK

AIM To investigate the anti-inflammatory effect and the possible mechanisms of an agonist of cannabinoid(CB) receptors, WIN55-212-2(WIN55), in mice with experimental colitis, so as to supply experimental evidence for its clinical use in future. METHODS We established the colitis model in C57BL/6 mice by replacing the animals' water supply with 4% dextran sulfate sodium(DSS) for 7 consecutive days. A colitis scoring system was used to evaluate the severity of colon local lesion. The plasma levels of proinflammatory cytokines, such as tumor necrosis factor-alpha(TNF-α) and interleukin-6(IL-6), and the myeloperoxidase(MPO) activity in colon tissue were measured. The expressions of cannabinoid receptors, claudin-1 protein, p38 mitogen-activated protein kinase(p38MAPK) and its phosphorylated form(p-p38) in colon tissue were determined by immunohistochemistry and Western blot. In addition, the effect of SB203580(SB), an inhibitor of p38, was investigated in parallel experiments, andthe data were compared with those from intervention groups of WIN55 and SB alone or used together. RESULTS The results demonstrated that WIN55 or SB treatment alone or together improved the pathological changes in mice with DSS colitis, decreased the plasma levels of TNF-α, and IL-6, and MPO activity in colon. The enhanced expression of claudin-1 and the inhibited expression of p-p38 in colon tissues were found in the WIN55-treated group. Besides, the expression of CB1 and CB2 receptors was enhanced in the colon after the induction of DSS colitis, but reduced when p38 MAPK was inhibited. CONCLUSION These results confirmed the anti-inflammatory effect and protective role of WIN55 on the mice with experimental colitis, and revealed that this agent exercises its action at least partially by inhibiting p38 MAPK. Furthermore, the results showed that SB203580, affected the expression of CB1 and CB2 receptors in the mouse colon, suggesting a close linkage and cross-talk between the p38 MAPK signaling pathway and the endogenous CB system.

Experimental research on daily deformation monitoring of steel box girder bridge based on BDS/GPS

In order to investigate the feasibility of BDS/GPS in the deformation monitoring of long-span bridges,analysis and research on aspects like number of visible satellites,PDOP value and monitoring precision are carried out. To analyze daily deformation characteristics of steel box girder bridge,observation data for 48 consecutive hours is computed by self-programmed software. Experiment results show that the monitoring-points on the bridge demonstrate obvious periodicity and recoverability in vertical and horizontal directions,meanwhile,changes in the elevation direction are relatively stable. The deformation-monitoring results of BDS/GPS combination system and GPS single system show good consistency. However,in a complex environment of the bridge,especially under the condition that satellite signals are severely affected,the advantages of BDS/GPS combination over GPS single system are more obvious.

Flotation and surface modification characteristics of galena,sphalerite and pyrite in collecting-depressing-reactivating system

The flotation tests and XPS analyses on galena,sphalerite and pyrite have been carried out in a collecting-depressing-reactivating system(hereafter referred as the CDR system).In this system,sulfide minerals were first collected and activated by the collector,and then depressed strongly by Ca(OH)2 in the strong alkaline solution,and finally reactivated by H2SO4.The flotation tests of pure minerals show that in this system the flotation behaviors of sphalerite and pyrite present irreversible characteristics along with the change of pulp potential.Furthermore,through the CDR system,considerable differences in the flotabilities between galena and sphalerite/pyrite are also observed.The XPS analysis results for galena,sphalerite and pyrite in a CDR system show that in the strong alkaline solution,some of the collectors,that have been already adsorbed on the mineral surface in the collecting process,are desorbed by Ca(OH)2.The XPS analysis results also show that in H2SO4 reactivating process,the surface hydroxides of galena are desorbed again by H2SO4 and replaced by diethyl dithiocarbamate,but those of sphalerite and pyrite are not desorbed.This flotation system may be applied to the bulk-differential flotation process of sulfur-bearing low-grade lead-zinc ores.

Experimental study on gas–liquid dispersion and mass transfer in shear-thinning system with coaxial mixer

The effects of impeller type, stirring power, gas flow rate, and liquid concentration on the gas–liquid mixing in a shear-thinning system with a coaxial mixer were investigated by experiment, and the overall gas holdup, relative power demand, and volumetric mass transfer coefficient under different conditions were compared. The results show that, the increasing stirring power or gas flow rate is beneficial in promoting the overall gas holdup and volumetric mass transfer coefficient, while the increasing system viscosity weakens the mass transfer in a shearing–thinning system. Among the three turbines, the six curved-blade disc turbine(BDT-6) exhibits the best gas pumping capacity; the six 45° pitched-blade disc turbine(PBDT-6) has the highest volumetric mass transfer coefficient at the same unit volume power.

Experimental study on performance that carbon dioxide inhibits coal oxidation and spontaneous combustion

Adopting oil-bath temperature programming experiment and gas chromatography, CO2＇s inhibitory performance on spontaneous combustion of Tingnan Coal Mine sample was analyzed. Through temperature rise rate test experiment, the accuracy, stability and reliability of the improved oil-bath temperature programming system applied in this experiment was proved to be superior to the traditional system. Spontaneous combustion characters parameters test of coal sample in pure air was carried out with this system and offered comparison standard for research in next stage. Temperature programming to coal sample was further conducted in oil-bath with different concentration of CO2. Testing results are compared with parameters of concentration of CO, O2, temperature, CO generation rate and O2 consumption rate tested and calculated in previous experiment in pure air. Methods of proportioning between concentration of CO and O2, CO concentration and temperature, CO generation rate and O2 consumption rate were applied to eliminate obstructions from certain external factors such as inlet of CO2; meanwhile influences of CO2 of different concentrations to coal oxidation and spontaneous combustion were investigated. Also CO2 inhibition technique was used in spontaneous combustion prevention in workface No. 106 of Tingnan Coal Mine, data collected from which indicate that CO2 performs well in inhibiting coal oxidation and spontaneous combustion.

Effect of temperature and heating rate on mechanical properties of magnesium alloy AZ31

Effects of temperature and heating rate on the mechanical properties of the tensile specimens of magnesium alloy AZ31 were experimentally investigated using a Gleeble-1500 thermo-mechanical material testing system.The metallurgraphs of the fracture section of the specimens were also experimentally observed and analyzed for exploring their failure mechanism under different temperatures and heating rates.The results show that the higher the temperature,the lower the ultimate strength of the specimens.And the higher the heating rate,the higher the ultimate strength of the specimens.The high temperatures and high heating rates will induce microvoids in the specimens which make the specimens failure under relatively low loads.

Loading System for Full-Scale Heavy-Duty Support Node Test with Multi-Directional Loading Requirements

This paper presents the design, analysis and experimental study of a loading system for heavy-duty nodes test based on a large-scale multi-directional in-plane loading device, which has been used in a full-scale heavy-duty support node test. Test loads of the support reached 6 567 kN with multi-directional loading requirements, which outrange the capacity of the available loading devices. Through the reinforcement of a large-scale multi-directional inplane loading device, the innovative design of a self-balanced load transferring device, and other arrangement considerations of the loading system, the test was implemented and the loading capacity of the ring was considerably enlarged. Due to the heavy loading requirements, some checking computations of the ring and the load transferring device outranged the limit of the Chinese national code "Code for Design of Steel Structures (GB 50017—2003)", thus elastic-plastic finite element (FE) analysis was carried out on the two devices, and also the real-time monitoring on the whole loading systems during experiments to ensure test safety. FE analysis and test results show that the loading system worked elastically during experiments.

Tests and error analysis of a self-positioning shearer operating at a manless working face

Self-positioning of a shearer is the key technology for mining with a man-less working face. In an underground coal mine all radio navigation; satellite positioning or celestial navigation methods have their limitations. We analyzed an inertial navi-gation system intended to guide the movement a shearer and designed a self-positioning device for the shearer. Simulation tests were also performed on the system. We analyzed the errors observed in these tests to show that the main reason for the low preci-sion of the self-positioning system is accumulated error in the inertial sensor. A Kalman filtering algorithm used in combination with the shearer motion model effectively reduces the measurement errors of the self-positioning system by compensating for gyroscopic drift. Finally, we built an error compensation model to reduce accumulated errors using continuous correction to provide self-positioning of the shearer within a certain range of accuracy.

Theoretical and experimental study on non-linear vibration characteristic of gear transmission system

In order to investigate the vibration of gear transmission system with clearance, a vibratory test-bed of the gear transmission system was designed. The non-linear dynamic model of the system was presented, with consideration of the effects of nonlinear dynamic gear mesh excitation, flexible rotors and bearings. Integration method was used to investigate the non-linear dynamic response of the system. The results imply that when the mesh frequency is near the natural frequency of gear pair, it is the first primary resonance, the bifurcation appears, and the vibration becomes to be chaotic motion rapidly. When the speed is close to the natural frequency of the first-order bending vibration, it is the second primary resonance, the periodic motion changes to chaos by period doubling bifurcation. The vibratory measurement of test-bed of the gear transmission system was performed. Accelerometers were employed to measure the high frequency vibration. Experimental results show that the vibration acceleration of the gear transmission system includes mesh frequency and sideband. The numerical calculation results of low speed can be validated by experimental results basically. It means that the presented non-linear dynamic model of the gear transmission system is right.

Performance of an Ultrafiltration Membrane Pilot System for Treatment of Waste Stabilization Lagoon Effluent

Bali Tourism Development Corporation＇s lagoon （BTDC lagoon） has been used for treating wastewaters that come from all facilities available in the Nusa Dua Resort tourist area. Reuse of the lagoon effluent is limited for some applications due to salt and suspended solid contents. Application of an integrated membrane system for improving the water quality of the lagoon effluent which is suitable for various uses is under consideration. In this work an ultraflltration （UF） pilot performance for possible pretreatment of Reverse Osmosis （RO） was investigated. The results showed that permeate quality was stable （less than 0.5 NTU）, regardless of concentrating and diluting retentate in each cycle and fouling for a long duration of operation. However, the water quality obtained with this membrane was not enough to be directly used. The permeate quality obtained from the UF system fulfils the requirement for the optimal operation of reverse osmosis. Moreover, appropriate intermittent-backwash operation was fairly effective to maintain the fluxes at a reasonable level.

Effect of heating-rate on failure temperature of pre-loaded magnesium alloy

The response and failure of magnesium alloy AZ31 specimens subjected to different pre-loaded-stress levels and heating rates were investigated with a Gleeble-1500 thermo-mechanical material testing system.It is found that the increases of either pre-loaded stresses or heating-rates decrease the failure temperatures of the specimens.The metallographs of the tested specimens were also observed.It is shown that the high heating-rate may cause stronger local thermal inconsistency,which remarkably increases the microdefects and reduces the macroscopic mechanical properties of the material.

Study on Biocompatibility of Cross-linked Hyaluronic Acid Derivatives

Objective:The cross-linked production,which was prepared by HA and cross-linking agent STMP,EDC,GP through cross-linking reaction,might be used in drug delivery system(DDS).To ensure the security of clinical application,the excellent properties such as none cell toxicity,nonirritant,none general toxicity,none immunological rejection are necessary.Methods:In accordance with the request of GB/T 16886.1 on security evaluation of medical biomaterials,cell toxicity test,hemolysis test,intracutaneous stimulation test,acute toxicity test,and hypersensitive test were required.Results:Cell toxicity of HA-STMP,HA-EDC,HA-GP were all less than 1.All hypersensitive tests were eligible.But HA-EDC,HA-GP produced different degrees of slight thrill,slight toxicity,hemolysis rate,which were larger than the standard value.Conclusion:HA-STMP possesses favourable biocompatibility,which is a kind of ideal biomaterials and drug carriers.

MEXIR： An Implementation of High Performance and High Precision on XML Retrieval

Traditional information retrieval systems respond to user queries with ranked lists of relevant documents. Since, XML （Extensible Markup Language） documents separate content and structure; XML-IR （information retrieval） systems are able to retrieve only the relevant portions of documents. Therefore, users who utilize an XML-IR system could potentially receive highly relevant and precise material. We have developed the XML information retrieval system by using MySQL and Sphinx, which we call MEXIR. In our system, XML documents are stored into one table that has fixed relational schema. The schema is independent of the logical structure of XML documents. Each node in XML documents is represented by labels that express the positions in XML tree, namely ADXPI scheme. Our system has performance experiments on INEX collections and shown an average up to four seconds better than GPX. In addition, it has been reduced the size of the data down by 82.29 % compare to GPX system.

The feasibility experimental study of pumping and shunting pump under pressure in water injection station

At present in the process of water injection station operation, starting and stopping the pump caused system pressure fluctuations, and the fluctuations caused many problems about downstream injection wells. In order to eliminate the fluctuations and reduce problems, taking start pump, connect pump test under pressure in the water injection station installed the rotor frequency control system Changqing oil field developed. During the experiment, by progressively increasing the pressure pump to verify start pump with pressure feasibility test, the result shows when the pressure in the 0-25MPa pressure start and connect pump can be realized, and forecast the maximum pressure of the current start of the station with pressure pump. Start pump with pressure achieve the elimination of pressure fluctuations, provide the prerequisites about realizeing stable water injection pressure, and ultimately realize oil field water injection station to be automatic water injection laid a foundation.

A Discussion on Dynamic Characteristics of Undisturbed Loess by Dynamic Triaxial Test

Based on the dynamic triaxial test system and using the fitted wave of the Wenchuan earthquake and 1 Hz constant amplitude sinusoid,the paper compares the results of tests on undisturbed loess samples under different loads and vibration modes but under same saturated conditions.Results of the comparative experiment show:The stress-strain curves have a similar trend under random seismic loading and constant amplitude sinusoidal loading,but the random seismic loading is more sensitive to failure strength of the undisturbed loess samples under the same stress.