多级节流智能控制装置的研制

针对现有井控单级节流系统已不能满足塔里木油田高压高产气井勘探开发的要求,提出多级节流的方法.由于液动节流阀和液动平板阀数量的增加,多级节流压井控制过程更加复杂,目前用于控制单级节流压井的手动控制装置就不能适合于对多级节流的控制,需要研制一种新型的多级节流智能控制装置.它不仅能通过手动操作来实施多级节流控制,也可以联结工控计算机实现智能化程序操作控制和系统工况监测.阐述了一种实现多级节流的程序控制与手动控制结合的液压操作控制装置的结构原理、特点和试验结果.     

Episodes of thoron exposure due to consumer products claiminghealth benefits of negative ions

In May 2018,the primetime news casted a shocking report saying that radon concentration on a certain model of bed mattress found to be as high as 2 200 Bq/m³.After a humble,the Nuclear Safety and Security Commission(NSSC) of Korea confirmed that significant amount of thoron gas is emanated from several mattress models marketed by a company claiming beneficial health effects of negative ions.Laboratory analysis showed that some internal fabric sheets of those mattresses contain high co...     

Sequential estimation of the mean of the negative binomial distribution

Insect population counts are often fit well by the negative binomial distribution. Estimation of the mean is of primary interest, and thus Anscombe's parameterization in terms of the mean, μ, and k has become almost standard. A common assumption is that k is known or a precise estimate of k is available. In this paper, sequential estimation of the mean with a prescribed degree of precision is investigated. The limiting behavior of each procedure is studied and Monte Carlo methods are employed to determine the behavior under moderate levels of precision.     

On uniform integrability and asymptotically risk-efficient sequential estimation

In the theory of asymptotically risk-efficient sequential estimation, one encounters uniform integrability of both positive and negative powers of stopping rules and moment convergence of randomly stopped statistics. We describe a simple approach to obtain these uniform integrability and moment convergence results, not only in the classical setting of i.i.d. observations but also for much more general stochastic sequences. We also use this approach to establish asymptotic risk efficiency of sequential estimators of means of stochastic sequences and to derive asymptotic approximations for the mean squared errors of ratio estimators.     

Is the analysis of molecular electronic structure of corrosion inhibitors sufficient to predict the trend of their inhibition performance

The often used approach in the corrosion inhibition studies employing quantum chemical calculations that relies on the correlation between molecular electronic structure parameters and inhibition effectiveness is critically examined. It is shown that the inhibition performance of three selected triazole-based corrosion inhibitors for copper - 3-amino-1,2,4-triazole (ATA), benzotriazole (BTAH), and 1-hydroxybenzotriazole (BTAOH) - cannot be explained on this basis in a sound manner. As the effectiveness of inhibitors is due to several phenomena, the outcome depends on the interplay between them and although molecular electronic parameters may provide many necessary elements, the involved effects can be estimated only approximately which may not always suffice. This supports the proposition that in general molecular electronic properties cannot be directly related to inhibition effectiveness - the actual relation is more involved - thus emphasizing the importance of a rigorous modeling of the inhibitor-surface interaction in the corrosion inhibition studies.     

Mortarless structures based on topological interlocking

We review the principle of topological interlocking and analyze the properties of the mortarless structures whose design is based on this principle. We concentrate on structures built of osteomorphic blocks – the blocks possessing specially engineered contact surfaces allowing assembling various 2D and 3D structures. These structures are easy to build and can be made demountable. They are flexible, resistant to macroscopic fractures and tolerant to missing blocks. The blocks are kept in place without keys or connectors that are the weakest elements of the conventional interlocking structures. The overall structural integrity of these structures depends on the force imposed by peripheral constraint. The peripheral constraint can be provided in various ways: by an external frame or features of site topography, internal pre-stressed cables/tendons, or self-weight and is a necessary auxiliary element of the structure. The constraining force also determines the degree of delamination developing between the blocks due to bending and thus controls the overall flexibility of the structure thus becoming a new design parameter.     

蒸压粉煤灰砖砌体性能试验研究

通过对蒸压粉煤灰砖砌体性能试验研究,表明蒸压粉煤灰砖满足国家规范要求．完全可以取代红砖。     

水套炉烟道吹扫机设计及应用

塔河油田奥陶系属于高黏、高凝稠油油藏,在集输过程中地面水套炉已成为单井、流程、场站重要设备之一,但随着炉道、烟道积碳严重,严重影响稠油集输生产。目前传统的清理烟道、烟筒的方式为人工清扫,采用该方式清理,现场维护工作量较大,同时难以对烟道U型管道清理干净。该文研制了一种适用于塔河油田现场应用的水套炉烟道吹扫机,该设备配置与烟道内径相匹配的刮刀,能针对U型管进行自由弧度弯曲清理,同时利用吹扫部件将烟道内刮削下来的积碳及时排出。通过现场试验,烟道清理时间大幅缩短,节省了人力物力,同时清理效果好,具有极高的推广价值。     

Vibration Characteristics of Fatigue Damage of Beam-Type Structural Components

We consider free vibration of an elastic cantilever beam with a closing edge crack. The crack is simulated by an elastic pivot whose compliance is taken to be finite and is determined from the energy equivalence criterion. An algorithm has been constructed for sequential calculation of the beam vibration modes for each beam vibration cycle, whereas the number of cycles is limited. It is demonstrated that the beam vibration modes other than the initially preset one are induced during the crack opening and closing. The distinct features of such modes have been studied. We have analyzed the sensitivity of the vibration-damage characteristics which are determined from the assessment of nonlinear distortions of the displacement, acceleration, and strain waveform of the cross sections of the beam with a closing crack.     

Large Magnetovolume Effect Induced by Embedding Ferromagnetic Clusters into Antiferromagnetic Matrix of Cobaltite Perovskite

Materials that show negative thermal expansion (NTE) have significant industrial merit because they can be used to fabricate composites whose dimensions remain invariant upon heating. In some materials, NTE is concomitant with the spontaneous magnetization due to the magnetovolume effect (MVE). Here the authors report a new class of MVE material; namely, a layered perovskite PrBaCo₂O_5.5+x (0 ≤ x ≤ 0.41), in which strong NTE [β ≈ ?3.6 × 10^?5 K^?1 (90–110 K) at x = 0.24] is triggered by embedding ferromagnetic (F) clusters into the antiferromagnetic (AF) matrix. The strongest MVE is found near the boundary between F and AF phases in the phase diagram, indicating the essential role of competition between the F‐clusters and the AF‐matrix. Furthermore, the MVE is not limited to the PrBaCo₂O_5.5+x but is also observed in the NdBaCo₂O_5.5+x . The present study provides a new approach to obtaining MVE and offers a path to the design of NTE materials.