大仰角钻孔简易快速安全封孔的实践

针对常规封孔时砂浆固结时间长、封孔耗材大、扫孔试压容易跑水、工序繁杂等缺点,利用套管预装砂浆、推板挤入试压的方法,对大仰角钻孔实施简易、快速、安全封孔。

岩浆侵入破碎顶板条件下放水孔的安全封孔

受大面积岩浆侵入影响,煤层顶板裂隙发育、顶板破碎,放水孔在试压时,周边锚杆、锚索孔全部跑水,利用"低压注浆封堵大裂隙、加入充填物高压注浆封堵固管"的新工艺,实现钻孔的安全封孔。

酷蛋安全包——Waha SecuredBOT安全封包软件

什么样的文件保护才叫安全?如果您看过影片MissionImpossible(《碟中谍》),那么一定觉得那个会自动删除的电子文件格外神秘。如今这样的技术已经不再是电影中的虚幻场景了,针对政府办公、安全部门文件保密等应用的产品已经走进了我们的实验室。

“CE”认证——我国安全鞋产品进入欧洲市场的通道

我国加入WTO为个人防护装备生产企业进入国际市场创造了有利条件。我国作为WTO成员可以享受成员国的关税待遇,没有了关税壁垒。但是,技术壁垒依然存在,这就是各国或地区的技术标准(规范)。出口国产品如不符合进口国的技术标准,则将被拒之门外。

封拱温度对砌石拱坝应力的影响研究

温度荷载是砌石拱坝应力控制性边界条件之一,其中年平均温度场和变化温度场为自然环境边界条件,较难人为控制,而封拱温度场可采取工程措施加以控制。对于不设横缝、整体上升砌筑的拱坝,各拱层封拱温度随施工期气温、建筑材料及砌体温度变化而变化,不是一个常数,合理选择封拱温度区间是控制砌石拱坝应力的有效手段。通过对砌石拱坝进行温度场和应力场仿真计算,分析了不同封拱温度场对砌石拱坝应力的影响规律,建立了安全封拱温度计算模型,并给出了相应的表达式。算例表明,采用该计算模型确定安全封拱温度区间,可有效控制坝体应力。

Transcatheter to Close the Patent Duetus Arteriosus and Atrial Septal Defects in Children

Objective: To evaluate the therapeutic effect, safety and complications oftranscathetering Amplatzer device in the closure of patent ductus arteriosus (PDA) and atrial septaldefects (ASD) in children. Methods: Patients with PDA (n = 25) and ASD ( n = 16), confirmed byechocardiography, were treated by transcatheterization. Amplatzer occluder device was placed by thetranscatheterization with the image support of X-ray and transthoracic echocardiography ( TTE) . TheTTE, ECG and X-ray examination were engaged to evaluate the therapeutic results on the time pointsof 24 h , 1, 3 , 6, 12 months after the operation, and all these cases were engaged to the follow-upexamination. Results: The cardioangiographic diameter was 13.0-28.0 mm ([19.3+-4.9] mm) in ASD and2.0-7.7 mm ([3.9+-1.5] mm) in PDA . The diameter of the Amplatzer occluder selected were 13.0-30.0mm ( [20.6+-5.1] mm) in ASD and 4.0-12.0 mm ([6.6+-1.9] mm) in PDA , respectively. All the Amplatzeroccluders were placed successfully. There were no complications during and after the operation.Very small residual shunt was still found soon after the operation in 10 cases , and there were noresidual or recanalization after three months of the operation. The pulmonary artery pressure andheart size were significantly decreased in follow-up examination . Conclusion: Transcatheteringclosure with Amplatzer device is an effective, simple and safe technique in the treatment of ASD andPDA in children.

ANALYSIS OF ABILITY FOR IGNITING METHANE OF WATER-CARRYING EXPLOSIVES

In this paper, the ability to ignite methane of water-carrying explosives is discussed in detail. The difference of the safety towards methane of water- carrying explosives and ammonite is analysed comparatively. lt is shown that the process of detonation reaction, the duration of fIame by combustible residues of detonation and the fineness of cooling salt in detonation products are important factors of the safety of explosive towards methane. Water-carrying explosives are safer than ammonite used in coal mines.

Quantum Secure Direct Communication and Quantum Sealed-Bid Auction with EPR Pairs

I present a new protocol for three-party quantum secure direct communication （QSDC） with a set of ordered M Einstein-Podolsky-Rosen （EPR） pairs. In the scheme, by performing two unitary operations and Bell state measurements, it is shown that the three legitimate parties can exchange their respective secret message simultaneously. Then I modify it for an experimentally feasible and secure quantum sealed-bid auction （QSBD） protocol. Furthermore, I also analyze th^ecurity of the protocol, and the scheme is proven to be secure against the intercept-and-resend attack, the disturbancb attack and the entangled-and-measure attack.

Security in gas discharge while unsealing a closed stope

Given the problem of harmful gas discharge in unsealing coal mining faces, we numerically simulated the process of change of gas flows and movements, We have pointed out that, at the moment of unsealing a closed stope, the gas discharge is naturally divided into two parts, i.e., the discharge of gas in the working face and that in the goaf, because of the difference in the spatial medium. The absolute volume of gas discharged has a tendency to decrease from its initial peak value to a final stable value. The rate of decrease and the time needed to reach a stable discharge are related to the scale of the mining stope. The discharge of gas from the working face is closely related to the amount of air distributed in the air return way. The most important thing in unsealing a stope is to have the initial peak volume of gas discharged well under control. A commonly used method in solving this problem is at first to use a small amount of air and then increasing it gradually. Our study shows that, by extracting gas from the upper corner, we can use a large volume of air at first in order to shorten considerably the discharge time and improve efficiency, thereby making mining, activitv safer.

Where do Random Rough Surfaces Fail？ Part I： Fracture Loci Safety Envelopes at Early Stages of Degradation

Damage on surfaces often compromises the efficiency of some types of energy production, the safety and reliability of components, and ultimately increases costs. The environment can degrade the structural integrity of surfaces in service by the accumulation of large numbers of small destructive events, which based on the Central Limit Theorem leads to a Gaussian distribution of pit depth. In order to develop safety envelopes relating fracture loci with topological parameters of a brittle material, scatter plots were obtained and analyzed. Starting with an engineering surface, after 6 to 9 micrometers of average degradation depth, safety envelopes could be developed using average roughness and two other proposed parameters. Interestingly, maximum pit depth showed very low correlation with the location of fracture, at the early stage of degradation studied. This is attributed to relaxation of stress concentration at a given pit location due to the assuaging effect caused by neighboring pits. Additionally, energy at fracture was obtained, and a maximum relaxation region was observed. Analytical and experimental study of this region, as well as ductility effects are currently under research.

Fluid-solid strong-interaction model of mechanical seals in reactor coolant pumps

The studies on the mechanisms and performances of the mechanical seals in reactor coolant pumps are very important for the safe operations of the pressurized water reactor power plants. Based on the hydrostatic mechanical seal in reactor coolant pumps, an analytical fluid-solid strong-interaction model is proposed in this paper. According to the design features and operafional principles of the seal, an analytical method to calculate the mechanical deformation of the seal assembly is developed based on the ring deformation theory. A strong-interaction algorithm combining the analysis of the mechanical deformation of the seal assembly and flow field between the seal faceplates is utilized, in which the three kinds of equations including the fluid domain, solid domain and coupling action are constituted in the same equations set and all the variables are solved simul- taneously. So the analytical fluid-solid strong-interaction model used for the seal is built. Moreover, the model is verified by the experimental results. Based on the model, the design parameters of the seal are studied. Two different conditions of the general case and fixed seal leakage rate are discussed respectively, and the regularities that the seal behaviors are affected by the parameters of the holding screws on the clamp rings and seal faceplates are obtained. The research results can provide a theoretical basis for performance analysis, design and assemblage of the seal. Compared to the numerical methods, the proposed model has the unique advantages of high efficiency, convenience and easy application of constraints.