风线“自动”压水法

凡从事手竿钓的钓线，在施钓操作中，不论是5～7星浮传统钓也好，用台钓标悬坠钓也好，也且不论钓点水深多少，用线长短，只要你投钩垂钓，并校好标位和可视的标垦（一般称为标示或标相），此时，以标示标目为界，垂于水面之下直至拴钩部位的钓线，就称为“水线”，正如我们平常所说的“水线多深”；而标示标目以上多余下的、便于钓竿操作的一部分水上钓线，

关于压载水法倾斜试验自由液面修正的分析

文章介绍了压载水法倾斜试验对于液体舱内自由液面修正的方法,重点讲解了移动压载水在规范中规定无须进行自由液面修正的原因,以及在实际计算中的处理办法,给大家一个清晰的思路,避免自由液面处理过程中发生少修正或重复修正等问题。

基于压载水法的50000 t半潜船倾斜试验测量参数敏感性分析

由于半潜船在主甲板完全没入水面后,船体水线面面积急剧减小,导致GM值较小,而倾斜试验读数误差会影响到空船重心高度,从而影响最终配载的GM值。文章以50 000 t半潜船为例,根据船舶静力学原理,针对压载水法倾斜试验的测量参数水尺、测深及摆锤读数开展敏感性分析。结果表明:摆锤读数及手工测深读数对倾斜试验结果影响较大,而水尺读数的影响较小;读数误差影响范围可能超过最小的GM值,因此对半潜船来说,倾斜试验的准确性极其重要。

50000吨级油船用压载水法进行倾斜试验介绍

倾斜试验是船舶在建造完成或接近完成的条件下为了确定船舶空船重量及重心的实际位置而进行的试验。现阶段标准方法是用压铁吊运法来进行。

From Chooz to the Ling'ao NPP:The Technology Transfer of Pressurized Water Reactor Technology from France to China

The transfer of pressurized water reactor(PWR)technology from France to China is an important event in the history of Sino-French scientific and technological relations.China has gradually achieved self-reliance in the field of PWR technology through the introduction and subsequent absorption of France's 900 MW reactors.Compared with the process of introducing and absorbing similar technology from the United States by France,China's experience has been more complicated.This circumstance reflects the differences in the nuclear power technology systems between the two countries.France's industrial strength and early acquisition of nuclear power technology laid a solid foundation for mastering PWR technology.On the other hand,although China established a weak foundation through the implementation of the"728 Project,"and tried hard to negotiate with France,the substantive content of the technology transfer was very limited.By way of the policy transition from"unhooking of technology and trade"to"integration of technology and trade,"China ultimately accomplished the absorption and innovation of PWR technology through the Ling'ao NPP.

Influence of confined water on the limit support pressure of tunnel face in weakly water-rich strata

In the process of shield tunneling through soft soil layers,the presence of confined water ahead poses a significant threat to the stability of the tunnel face.Therefore,it is crucial to consider the impact of confined water on the limit support pressure of the tunnel face.This study employed the finite element method(FEM)to analyze the limit support pressure of shield tunnel face instability within a pressurized water-containing layer.Subsequently,a multiple linear regression approach was applied to derive a concise solution formula for the limit support pressure,incorporating various influencing factors.The analysis yields the following conclusions:1)The influence of confined water on the instability mode of the tunnel face in soft soil layers makes the displacement response of the strata not significant when the face is unstable;2)The limit support pressure increases approximately linearly with the pressure head,shield tunnel diameter,and tunnel burial depth.And inversely proportional to the thickness of the impermeable layer,soil cohesion and internal friction angle;3)Through an engineering case study analysis,the results align well with those obtained from traditional theoretical methods,thereby validating the rationality of the equations proposed in this paper.Furthermore,the proposed equations overcome the limitation of traditional theoretical approaches considering the influence of changes in impermeable layer thickness.It can accurately depict the dynamic variation in the required limit support pressure to maintain the stability of the tunnel face during shield tunneling,thus better reflecting engineering reality.

Geostress measurements near fault areas using borehole stress-relief method

To minimize negative effects of geostress distribution on mining safety near the fault areas, the UPM40 triaxial geostress testing system was introduced to conduct in-situ geostress measurements at three sites and nine points by the borehole stress-relief method. The results of strain?confining pressure curves show that rock masses at the three measuring sites exhibit comprehensive linear elasticity in spite of various fissures or cracks within rocks. Horizontal and vertical stress components distribute discrepantly near the fault areas, and the maximum lateral pressure coefficient is as high as 6.15. The maximum principle stress ranges from 8.01 to 14.93 MPa, and stress directions are in the range of N78.07°W?N17.55°W. Geostresses near fault areas are dominated by the horizontal tectonic stresses, while the lower values, compared to those under similar geological conditions are due to stress release by the fault. Additionally, the fault and shear stress nearby are partially responsible for asymmetric elongation and southwesterly migration of orebodies.

混凝土抗渗性能检测探讨

混凝土抗渗性能检测在我国路桥、建筑与水利等工程方面应用十分广泛,通过抗渗性能的检测能够有效的保证混凝土的耐久性。然而混凝土的渗透试验是一项艰难而耗时的工作,如何进行试验成为试验人员的工作重点。本文重点介绍了几种混凝土抗渗性能检测方法。

桑树播种育苗

桑树浑身是宝,干、枝、叶、果,皮、根是建材、家俱、医药、食品、饲料、轻工等的原材料。在适合种植的地区应大力提倡多种桑树。在自治区将南疆定为栽桑养蚕基地后,一个栽桑致富势头在发展。各地群众栽桑积极性很高,但桑苗不足,桑树育苗急需大力发展。现就桑树播种育苗的一些技术措施简述如下。一、育苗地的选择与作床。

Observation of Mitosis and Meiosis in Rice Cells by Simple Squash Method

[Objective] The aim of this study was to establish a feasible squashing technique for chromosome and obtain data of rice chromosome. [Method] With the materials of rice root tips and anther, the specimen was prepared by the modified squash method, and microscopic observation of mitosis and meiosis in rice cells was also carried out. [ Result] Mitosis in rice cells included interphase, prophase, metaphase, anaphase and telophase. Chromosome in metaphase shortened to the minmum, which was a good time for observing and investigating chromosome. However, meiosis in rice cells included meiosis Ⅰ and meiosis Ⅱ. Chromosome replication appeared in meiosis Ⅰ, while cell division only appeared in meiosis Ⅱ. [ Conclusion] The modified squashing technique for rice chromosome can obtain accurate data of rice chromosome, which provides evidence for genetic breeding.

Effect of ground stress on hydraulic fracturing of methane well

Most of the coal reservoirs in China are of low-permeability, so hydraulic fracturing is widely used to improve the per- meability in the extraction of gas by ground drilling. The ground stress around the well was analyzed by using theory of elasticity. The pressure when the well fractured is formulated and the effect of ground stress on pressure is discussed. The effect of ground-stress-differences on hydraulic fracturing was analyzed by using the numerical software RFPA2D-Flow in reference to the tectonic stress in Jincheng coal area. The results show that: 1) the position where initial fracture appears is random and fracture branches emerge when the fractures expand if ground stresses in any two directions within a horizontal plane are equal; 2) other- wise, the fractures expand in general along the direction of maximum ground stress and the critical pressure decreases with in- creasing ground-stress-differences and 3) the preferred well-disposition pattern is diamond shaped. The preferred well spacing is 250 m×300 m. This study can provide a reference for the design of wells.

Timing of advanced water flooding in low permeability reservoirs

It is very important to design the optimum starting time of water injection for the development of low permeability reservoirs. In this type of reservoir the starting time of water injection will be affected by a reservoir pressure-sensitive effect. In order to optimize the starting time of water injection in low permeability reservoirs, this effect of pressure change on rock permeability of low permeability reservoirs was, at first, studied by physical simulation. It was shown that the rock permeability decreases exponentially with an increase in formation pressure. Secondly, we conducted a reservoir engineering study, from which we obtained analytic relationships between formation pressure, oil production rate, water production rate and water injection rate. After our physical, theoretical and economical analyses, we proposed an approach which takes the pressure-sensitive effect into consideration and designed the optimum starting time of water injection, based on the principle of material balance. Finally, the corresponding software was developed and applied to one block of the Jiangsu Oilfield. It is shown that water injection, in advance of production, can decrease the adverse impact of the pressure-sensitive effect on low permeability reservoir development. A water-flooding project should be preferably initiated in advance of production for no more than one year and the optimum ratio of formation pressure to initial formation pressure should be maintained at a level between 1.05 and 1.2.

An underwater acoustic data compression method based on compressed sensing

The use of underwater acoustic data has rapidly expanded with the application of multichannel, large-aperture underwater detection arrays. This study presents an underwater acoustic data compression method that is based on compressed sensing. Underwater acoustic signals are transformed into the sparse domain for data storage at a receiving terminal, and the improved orthogonal matching pursuit(IOMP) algorithm is used to reconstruct the original underwater acoustic signals at a data processing terminal. When an increase in sidelobe level occasionally causes a direction of arrival estimation error, the proposed compression method can achieve a 10 times stronger compression for narrowband signals and a 5 times stronger compression for wideband signals than the orthogonal matching pursuit(OMP) algorithm. The IOMP algorithm also reduces the computing time by about 20% more than the original OMP algorithm. The simulation and experimental results are discussed.

Adsorption Refrigeration Performance of Shaped MIL-101-Water Working Pair

A new metal-organic framework of MIL-101 was synthesized by hydrothermal method and the powder prepared was pressed into a desired shape. The effects of molding on specific surface area and pore structure were investigated using a nitrogen adsorption method. The water adsorption isotherms were obtained by high vacuum gravimetric method, the desorption temperature of water on shaped MIL-101 was measured by thermo gravimetric analyzer, and the adsorption refrigeration performance of shaped MIL-101-water working pair was studied on the simulation device of adsorption refrigeration cycle system. The results indicate that an apparent hysteresis loop ap-pears in the nitrogen adsorption/desorption isotherms when the forming pressure is 10 MPa. The equilibrium ad-sorption capacity of water is up to 0.95 kg·kg^-1 at the forming pressure of 3 MPa （MIL-101-3）. The desorption peak temperature of water on MIL-101-3 is 82℃, which is 7 ℃ lower than that of silica gel, and the desorption temperature is no more than 100 ℃. At the evaporation temperature of 10 ℃, the refrigeration capacity of MIL-101-3-water is 1059 kJ·kg^-1, which is 2.24 times higher than that of silica gel-water working pair. Thus MIL-101-water working pair presents an excellent adsorption refrigeration performance.

Three-dimensional consolidation deformation analysis of porous layered soft soils considering asymmetric effects

Long-term settlements for underground structures, such as tunnels and pipelines, are generally observed after the completion of construction in soft clay. The soil consolidation characteristic has great influences on the long-term deformation for underground structures. A three-dimensional consolidation analysis method under the asymmetric loads is developed for porous layered soil based on Biot's classical theory. Time-displacement effects can be fully considered in this work and the analytical solutions are obtained by the state space approach in the Cartesian coordinate. The Laplace and double Fourier integral transform are applied to the state variables in order to reduce the partial differential equations into algebraic differential equations and easily obtain the state space solution. Starting from the governing equations of saturated porous soil, the basic relationship of state space variables is established between the ground surface and the arbitrary depth in the integral transform domain. Based on the continuity conditions and boundary conditions of the multi-layered pore soil model, the multi-layered pore half-space solutions are obtained by means of the transfer matrix method and the inverse integral transforms. The accuracy of proposed method is demonstrated with existing classical solutions. The results indicate that the porous homogenous soils as well as the porous non-homogenous layered soils can be considered in this proposed method. When the consolidation time factor is 0.01, the value of immediate consolidation settlement coefficient calculated by the weighted homogenous solution is 27.4% bigger than the one calculated by the non-homogeneity solution. When the consolidation time factor is 0.05, the value of excess pore water pressure for the weighted homogenous solution is 27.2% bigger than the one for the non-homogeneity solution. It is shown that the material non-homogeneity has a great influence on the long-term settlements and the dissipation process of excess pore water pressure.

Computation of one—dimensional consolidation of double layered ground using differential quadrature method

The authors give the solution to the problem of one-dimensional conso l idation of double-layered ground with the use of the differential quadrature me t hod. Case studies showed that the computational results for pore-water pressure in soil layer agreed with those of analytical solution; and that in the computat ional results for the interface of soil layer also agreed with those of the anal ytical solution except for the small discrepancies during shortly after the star t of computation. The advantages of the solution presented in this paper are tha t compared with the analytical solution, it avoids the cumbersome work in solvin g the transcendental equation for eigenvalues, and in the case of the Laplace transform s olution, it can resolve the precision problem in the numerical solution of long time inverse Laplace transform. Because of the matrix form of the solution in th is paper, it is convenient for formulating computational program for engineering practice. The formulas for calculating double-layered ground consolidation may be easily extended to the case of multi-layered soils.

Treating ballast water with hydroxyl radical on introduced organisms

With physical method of micro-gap gas discharge, a large amount of hydroxyl radical can be produced in 20t/h pilot-scale system using the ionization of 02 and H2O. In this paper, the effect of biochemistry of hydroxyl radicals on introduced organisms in ballast water was experimentally investigated. The results indicate that the contents of chlorophyl-a, chlorophyl-b, chlorophyl-c and carotenoid are decreased by 35%-4% within 8.0s and further to the lowest limit of test 5 minutes. In addition, the main reasons of cell death are the lipid peroxidation, the strong destruction to the monose, amylose, protein, DNA and RNA of cell, and damage in CAT, POD and SOD of antioxidant enzyme system.

An Alternative Approach for the Determination of Soil Water Mobility

A new laboratory method was proposed to establish an easily performed standard for the determination of mobile soil water close to real conditions during the infiltration and redistribution of water in a soil. It consisted of applying a water volume with a tracer ion on top of an undisturbed ring sample on a pressure plate under a known suction or pressure head. Afterwards, soil water mobility was determined by analyzing the tracer-ion concentration in the soil sample. Soil water mobility showed to be a function of the applied water volume. No relation between soil water mobility and applied pressure head could be established with data from the present cxperiment. A simple one- or two-parameter equation can be fitted to the experimental data to parameterize soil water mobility as a function of applied solute volume. Sandy soils showed higher mobility than loamy＂ soils at low values of applied solute volumes, and both sandy and loamy soils showed an almost complete mobility at high applied solute volumes.

Key parameters for low temperature warm compaction of high density iron-based P/M materials

In order to reduce powder temperature to lower than 100℃ in warm compaction by changing polymer lubricant design, powder flowability, warm compacting behavior, lubricating mode as well as ultimate tensile strength after sinter-hardening and tempering were investigated systematically. By means of low temperature warm pressing and sintered hardening technique, samples with the sintered densities of 7.407.45g/cm3 and the strengths of 950 1390MPa are achieved as the early compacting pressure is 686735MPa.

Numerical analysis of coal-gas flow and pressure relief on the mining method of extreme short-range protective strata

The coal-gas existing condition was ameliorated in the coal seams prone to coal-gas outburst adopting the mining method of protective strata.The gas volume and the gas pressure were reduced synchronously in the protected coal seam,and the coal seam of high permeability prone to the coal-gas outburst was changed into that of low perme- ability with no proneness to the coal-gas outburst.The D_(15)coal seam was treated as the protective strata,and the D_(16-17)coal seam was treated as the protected strata in the Fifth coal mine in the Pingdingshan Coal Mining Group.The distance between the two coal seams was 5 m averagely,clarified into the extreme short-range protective strata.The numerical analysis was based on the theory of the porous media flow with the finite ele- ment method.The gas flow process and the change mechanism of the coal-gas pressure were analyzed in the process of mining the protective strata.