“■筒”考辨

本文對敦煌雜字書中出現的"■(■)筒"進行考證辨析。通過佛經音義和歷史文獻中的語料,推斷"■筒"即"濺筒"、"唧筒",是農業生産中常用的一種人力汲水工具,後世逐漸推廣應用於消防和軍事等方面,其詞義也隨之擴大,凡"氣泵"皆可稱"唧筒"。

Towing characteristics of large-scale composite bucket foundation for offshore wind turbines

In order to study the towing dynamic properties of the large-scale composite bucket foundation the hydrodynamic software MOSES is used to simulate the dynamic motion of the foundation towed to the construction site.The MOSES model with the prototype size is established as the water draft of 5 and 6 m under the environmental conditions on site.The related factors such as towing force displacement towing accelerations in six degrees of freedom of the bucket foundation and air pressures inside the bucket are analyzed in detail.In addition the towing point and wave conditions are set as the critical factors to simulate the limit conditions of the stable dynamic characteristics.The results show that the large-scale composite bucket foundation with reasonable subdivisions inside the bucket has the satisfying floating stability.During the towing process the air pressures inside the bucket obviously change little and it is found that the towing point at the waterline is the most optimal choice.The characteristics of the foundation with the self-floating towing technique are competitive for saving lots of cost with few of the expensive types of equipment required during the towing transportation.

Formation mechanism and criterion of linear segregation in ZL205A alloy

The experiments and numerical simulation were conducted for ZL205A aluminum alloy cylindrical shell casting. The formation mechanism of the linear segregation produced by the low pressure die casting (LPDC) process was investigated. And the heat transfer of the casting during solidification process was analyzed by simulation technique, resulting from the information of linear segregation obtained by plenty of experiments. The new linear segregation criterion was proposed through the simulation and experimental results. It was found that the melting metal with high Cu contents was feeding the crack shrinkage formed by the tearing under the effect of feeding pressure during the later solidification, which led to the formation of linear segregation. The control methods for the linear segregation were suggested based on the proposed mechanism. Finally, the criterion of linear segregation was confirmed by the production of the actual castings.

Influence of Perforation on Formation Fracturing Pressure

Hydraulic fracturing treatments of oil wells are greatly affected by the perforation parameters selected. The three-dimensional finite element model together with the tensile criterion of rock materials is employed to systematically investigate the influence of perforation parameters, such as perforation density, perforation orientation, perforation diameter, and perforation length as well as wellbore ellipticity, in vertical wells on the formation fracturing pressure. Based on a six-month simulation research in the University of Petroleum, China, several conclusions are drawn for the first time. Perforation density and perforation orientation angle are the most important parameters controlling the formation fracturing pressure. As the perforation density increases, the fracturing pressure decreases, not linearly but progressively. The fracturing pressure increases with the perforation orientation angle only when the angle is less than 45 degrees, and the relationship becomes very flat when the angle is 45 degrees. However, with regards to the perforation diameter and perforation length, their influences are much slighter. The wellbore ellipticity has a significant effect on the formation fracturing pressure. It is obvious that fracturing pressure increases linearly with the ellipticity of the wellbore.

Three-dimensional orebody modelling and intellectualized longwall mining for stratiform bauxite deposits

Acoupled biharmonic spline and linear interpolation algorithm was proposed to create a three-dimensional smooth deposit model with minimal curvature containing grade and position data. To obtain the optimal technical parameters, such as cuttingheight and drum diameter, a virtual longwall mining procedure was modelled by simulating the actual fully mechanized longwall mining process. Based on the above work, a bauxite deposit in a longwall mining panel was modelled by scattered grade data from ores sampled on the entry wall. The deposit was then demarcated by industrial indexes and sliced according to the virtual longwallmining procedure. The results show that the proposed interpolation algorithm can depict the stratiform structure of bauxite depositsand that the uncovered bauxite deposit has high proportions of high-grade and rich ore. The ranges of optimal cutting height and drum diameters are 1.72-2.84 m and 1.42-1.72 m, respectively. Finally, an intellectualized longwall mining procedure was designed to guide the mining process with the lowest dilution and loss rates.

Radial mixing and segregation of granular bed bi-dispersed both in particle size and density within horizontal rotating drum

Taking simultaneous variations in both particle volume and density into account, the radial mixing and segregation of binary granular bed in a rotating drum half loaded were investigated by a 3D discrete element method. Then, based on the competition theory of condensation and percolation, radial segregation due to differences in particle volume and/or density was analyzed. The results show that if either percolation effect induced by volume difference or condensation effect induced by density difference dominates in the active layer of moving bed, separation will occur. Controlling the volume ratio or density ratio of the two types of particles can achieve an equilibrium state between percolation and condensation, and then homogenous mixture can be obtained. When the percolation balances with the condensation, the relationship between volume ratioand density ratiopresents nearly a power function. Scaling up a rotating drum will not affect the mixing degree of the granular bed so long as the volume ratio and density ratio are predefined.

A general method for silo classification using rupture plane

A new method is presented for silo classification using the rupture plane in the storage. The proposed method is based on the formula of rupture plane orientation determined by the aspect ratio of specified silos and involves the effects of the conical angle of the storage surface, so it can deal with two cases： the conical angle of the storage surface and the flat storage surface. Compared with the two popular methods based on the silo-aspect ratio and the silo rupture plane, respectively, in current engineering design, the new method can give a range of critical aspect ratios to classify deep silos and squat silos according to the conical angle of the storage surface or the fiat storage surface. Moreover, the range covers the critical aspect ratios obtained from the existing classification methods including the Chinese code based on silo aspect ratios, the German code, Reimbert brothers＇ definition and Liang et al. ＇s definition, so it is a more general method to classify silos and the existing methods can be viewed as special cases of the presented method.

ANALYTICAL SOLUTION OF AXIAL SYMMETRICAL WALL TEMPERATURE DISTRIBUTION FOR HOLLOW CYLINDER

Using the variable transformation method,the formulae of the axial symmetrical wall temperature distribution during steady heat conduction of a hollow cylinder are derived in this paper.The wall temperature distribution and the wall heat flux distribution in both axial and radial direction can be calculated by the temperature distribution of the liquid medium both inside and outside the cylinder with temperature changing in axial direction.The calculation results are almost consistent with the experience results.The applicative condition of the formulae in this paper consists with most of practice.They can be applied to the engineering calculation of the steady heat conduction.The calculation is simple and accurate.

ADOPT护理模式对结肠造口病人护理知识和适应水平的影响

[目的]探讨ADOPT护理模式对直肠癌术后永久性结肠造口病人造口护理知识和造口适应水平的影响。[方法]将2014年8月—2015年3月行永久性直肠造口术病人66例随机分为对照组和观察组。对照组术后实施常规护理,观察组术后在常规护理基础上实施ADOPT护理模式。出院后均进行电话访问和家庭访问。于术后第1天、出院时和出院后3个月评估两组病人造口护理知识和造口适应水平。[结果]出院时和出院3个月后观察组造口护理知识得分和适应水平得分明显高于对照组(P<0.05)。[结论]ADOPT模式能显著提高永久性结肠造口病人造口护理知识水平,缓解造口病人负性情绪,提高病人生理、心理和社会适应水平,促进病人身心康复。

Two New Species of Nymphulinae(Lepidoptera:Crambidae) from China

Two following new species of Nymphulinae are described: Paracymoriza convallata, sp. nov., Parapoynx candida, sp. nov. They are collected separately from Fujian and Tianjin. The photographs and the male or female genitalia of the new species are provided.

Model test of the cutting properties of a shearer drum

According to similarity theory, we carried out a dimensional analysis of the shearer drum correlation parameters and built similarity criteria. Based on these, similarity models of shearer drums were developed. Simultaneously, based on an estab- lished cutting testbed of the coal and rock, cutting tests of different pick arrangements of the drum models were carried out, where the compressive strength of the analogous cutting material was 2.48 MPa and the drum rotary speed 67.5 r/min. The variance, the mean values, maxima and mean maxima of the torque load were analyzed for different type drum models. Moreover, the relation-ships between the type of pick arrangements and the cutting lump coal percentage were studied. The results indicate that the load fluctuation of the sequence drum is larger than that of the punnett square drum in the cutting process and the lump coal percentage and economic benefits of the sequence drum are inferior to the punnett square drum. We conclude that the punnett square drum is superior to the sequence drum.

Fluid characteristic of multiphase fluid in annular space between pump barrel and plunger

The pump performance parameters,such as pump pressure,plunger friction and pump valve resistance,are fundamental parameters of optimal design of pump efficiency and sucker rod pumping system (SRPS).In this paper,considering the characteristic of geometrical nonlinear and rheology property of multiphase fluid,the pump performance parameters are studied.Firstly,a dynamics model of annular fluid flow is built.In the detail,a partial differential equation of annular fluid is established and a computing model of fluid pressure gradient is built.Secondly,the simulation models of plunger friction and hydraulic resistance of pump valve are built.Finally,a novel simulation method of fluid pressure in annular space is proposed with software ANSYS.In order to check up the correction of models proposed in this paper,the comparison curves of experiment and simulation results are given.Based on above model,the whole simulation model of plunger pump is simulated with Visual Basic 6.0.The results show that the fluid friction of pump plunger and instantaneous resistance of pump valve are nonlinear.The impact factors of pump performance parameters are analyzed,and their characteristic curves are given,which can help to optimize the pump motion parameters and pump structural.

Conventional triaxial compression on hollow cylinders of sandstone with various fillings: Relationship of surrounding rock with support

The interaction of surrounding rock with a support system in deep underground tunnels has attracted extensive interest from researchers.However,the effect of high axial stress on tunnel stability has not been fully considered.In this study,compression tests with and without confining pressure were conducted on solid specimens and hollow cylinder specimens filled with aluminium,lead,and polymethyl methacrylate(PMMA)to investigate the strength,deformation and failure characteristics of circular roadways subjected to high axial stress.The influence of the three-dimensional stress on the surrounding rock supported with different stiffness was studied.The results indicate that the strength and peak strain of hollow cylinders filled with PMMA are higher than those of hollow cylinders filled with aluminium or lead,indicating that flexible retaining is beneficial for roadway stability.The results obtained in this paper can contribute to better understanding the support failure of a buried roadway subjected to high axial stress and thus to analyzing and evaluating roadway stability.

Depression and elevation internal solitary waves in a two-layer fluid and their forces on cylindrical piles

Both large amplitude depression and elevation internal solitary waves （ISWs） were observed on the continental shelf of the northwest South China Sea （SCS） during the Wenchang Intemal Wave Experiment. In this study, we investigate the characteristics of depression and elevation ISWs based on comparisons between observational results and internal wave theories. It is suggested that the large amplitude depression wave is better represented by the extended Korteweg-de Vries （EKdV） theory than by the KdV model, whereas the large amplitude elevation wave is in better agreement with the KdV equation than with the EKdV theory. Wave-induced forces on a supposed small-diameter cylindrical pile by depression and elevation waves are also estimated using the internal wave theory and Morison formula. The wave-induced force by elevation ISWs is rarely reported in the literature. It is found that the force induced by the elevation wave differs significantly fi＇om that by the depression wave, and the elevation wave generally produces greater force on the pile in the lower water column than the depression wave. These results show that ISWs in the study area can present a serious threat to ocean engineering structures, and should not be ignored in the design of oil platforms and ocean operations.

Influence of infilling stiffness on mechanical and fracturing responses of hollow cylindrical sandstone under uniaxial compression tests

Hollow cylindrical sandstone specimens filled with Al,Pb and polymethyl methacrylate(PMMA),as well as hollow and solid specimens were tested under monotonic unconfined compression.The discrepancies in the elastic modulus,unconfined compressive strength and failure pattern of the specimens were studied and then illustrated.The interaction stress threshold and localized failure stress threshold were identified by the strain gauges on the rock and filling rod.The results indicated that unobvious changes in the strength and elastic modulus were found between the solid and hollow specimens,while for the hollow specimens with infillings,the strength decreases with increasing the stiffness of the infilling material.The filling material with a higher stiffness leads to a high hoop stress,and hence a stronger interfacial force.The specimens coupled with filling rod are mainly fractured with tensile cracks,while the solid and hollow specimens are typically split into blocky fragments with dominated shear fractures.Finally,the equivalent inner pressure in the opening was theoretically derived.The findings suggested in the experiments can be well explained using the theoretical thick-walled cylinder model.

Safety analysis of stability of surface gas drainage boreholes above goaf areas

As longwall caving mining method prevails rapidly in China coal mines, amount of gas emission from longwall faces and goaf area increased significantly. Using traditional gas drainage methods, such as drilling upward holes to roof strata in tailgate or drilling inseam and cross-measure boreholes, could not meet methane drainage requirements in a gassy mine. The alternative is to drill boreholes from surface down to the Iongwall goaf area to drain the gas out. As soon as a coal seam is extracted out, the upper rock strata above the goaf start to collapse or become fractured depending upon the rock characteristics and the height above the coal seam. During overlying rock strata being fractured, boreholes in the area may be damaged due to ground movement after the passage of the Iongwall face. The sudden damage of a borehole may cause a Iongwall production halt or even a serious mine accident. A theoretical calculation of the stability of surface boreholes in mining affected area is introduced along with an example of determination of borehole and casing diameters is given for demonstration. By using this method for the drilling design, the damage of surface boreholes caused by excessive mining induced displacement can be effectively reduced if not totally avoided. Borehole and casing diameters as well as characteristics of filling materials can be determined using the proposed method by calculating the horizontal movement and vertical stain at different borehole depths.

Experimental Investigation of TARMAX Model for Modeling of Hydrodynamic Forces on Cylinder-like Structures

A new approach that models lift and drag hydrodynamic force signals operating over cylindrical structures was developed and validated. This approach is based on stochastic auto regressive moving average with exogenous （ARMAX） input and its time-varying form, TARMAX. Model structure selection and parameter estimation were discussed while considering the validation stage. In this papel; the cylindrical structure was considered as a dynamic system with an incoming water wave and resulting forces as the input and outputs, respectively. The experimental data, used in this study, were collected from a full-scale rough vertical cylinder at the Delft Hydraulics Laboratory. The practicality of the proposed method and also its efficiency in structural modeling were demonstrated through applying two hydrodynamic force components. For this purpose, an ARMAX model is first used to capture the dynamics of the process, relating in-line forces provided by water waves; secondly, the TARMAX model was applied to modeling and analysis of the lift forces on the cylinder. The evaluation of the lift force by the TARMAX model shows the model is successful in modeling the force from the surface elevation.

Effects of surface finish and treatment on the fatigue behaviour of vibrating cylinder block using frequency response approach

This paper presents the effects of surface finish and treatment on the high cycle fatigue behaviour of vibrating cylinder block of a new two-stroke free piston engine at complex variable amplitude loading conditions using frequency response approach. Finite element modelling and frequency response analysis was conducted using finite element analysis software Package MSC.PATRAN/MSC.NASTRAN and fatigue life prediction was carded out using MSC.FATIGUE software. Based on the finite element results, different frequency response approach was applied to predict the cylinder block fatigue life. Results for different load histories and material combinations are also discussed. Results indicated great effects for all surface finish and treatment. It is concluded that polished and cast surface finish conditions give the highest and lowest cylinder block lives, respectively; and that Nitrided treatment leads to longest cylinder block life. The results were used to draw contour plots of fatigue life and damage in the worst or most damaging case.

Factors affecting thin coal seam shearer drum coal-loading performance by a model test method

To solve the problem of a low coal-loading rate being exhibited by the drum shearer on Chinese thin coal seams,systematic tests and research were performed to study the pivotal factors’influences on drum coal-loading rate using a model test method.The effects of the drum hub diameter,cutting depth,vane helix angle,drum rotation speed and hauling speed on drum coal-loading rate were determined under circumstances of coal-loading with drum ejection and pushing modes,and reasons for these phenomena were analyzed.The results indicate that the influence of the drum cutting depth on the drum coal-loading rate is the most significant.The parameters of hub diameter,drum rotation speed and hauling speed can influence the drum coal-loading rate by cutting the coals’filling rate in the drum.The parameters of vane helix angle and drum rotation speed can influence drum coal-loading rates by influencing the ratio of cutting coals’tangential and axial speed in the drum.The coal-loading rate with drum ejection is clearly higher than that observed with drum pushing.Research in this study can provide support to design the drum structure and select drum operational parameters for a thin coal seam shearer.

Stress analytical solution for plane problem of a double-layered thick-walled cylinder subjected to a type of non-uniform distributed pressure

The stress state around circular openings,such as boreholes,shafts,and tunnels,is usually needed to be evaluated.Solutions for stresses,strains and ultimate bearing capacities of pressurized hollow cylinder are common cases.Stress analytical method for plane problem of a double-layered thick-walled cylinder subjected to a type of non-uniform pressure on the outer surface and uniform radial pressure on the inner surface is given.The power series method of complex function is used.The stress analytical solution is obtained with the assumption that two layers of a cylinder are fully contacted.The distributions of normal and tangential contact stress along the interface,tangential stress on the inner boundary and stresses in the radial direction at θ=0°,45° and 90°,are obtained.An example indicates that,when the elastic modulus of the inner layer of a double-layered thick-walled cylinder is smaller than that of the outer layer,the tangential stress is smaller than that in the corresponding point for a traditional cylinder composed of homogeneous materials.In that way,stress concentration at the inner surface can be alleviated and the stress distribution is more uniform.This is a capable way to enhance the elastic ultimate bearing capacity of thick-walled cylinder.