复合注浆封孔在高压注水解危煤层冲击地压中的应用

在煤层注水治理冲击地压的过程中,为了提高注水压力的高压持续时间,增大注水解危的效果,研究了注水钻孔封堵体周围煤体裂隙对高压注水泄漏的影响。结果表明,钻孔封堵体外侧煤体中的漏水通道是客观存在的,通过在封堵段两端头布置化学浆布袋,形成封堵段密封空间,再将高压水玻璃—水泥浆液注入到该封堵段,让高压水玻璃—水泥浆液渗入到煤体裂隙,可以有效充填封堵段外侧煤壁内的漏水通道,形成理想的高压注水封堵段,在治理冲击地压隐患方面取得了较好的效果。

Wavelet domain adaptive filtering algorithm for removing the seamless pipe noise contained in the magnetic flux leakage data

With the widespread application and fast development of gas and oil pipeline network in China, the pipeline inspection technology has been used more extensively. The magnetic flux leakage （MFL） method has established itself as the most widely used in-line inspection technique for the evaluation of gas and oil pipelines. The MFL data obtained from seamless pipeline inspection is usually contaminated by the seamless pipe noise （SPN）. SPN can in some cases completely mask MFL signals from certain type of defects, and therefore considerably reduces the detectability of the defect signals. In this paper, a new de-noising algorithm called wavelet domain adaptive filtering is proposed for removing the SPN contained in the MFL data. The new algorithm results from combining the wavelet transform with the adaptive filtering technique. Results from application of the proposed algorithm to the MFL data from field tests show that the proposed algorithm has good performance and considerably improves the detectability of the defect signals in the MFL data.

Enhanced Side-Channel Leakage Detection Method by Considering Combinational Logic

In this paper,we propose a hybrid power model that includes the power consumption of not only the registers but also part of the combinational logic.By doing knownkey analysis with this hybrid model,power side-channel leakage caused by correct keys can be detected.In experiment,PRINTcipher and DES algorithms were chosen as analysis targets and combinational logic s-box unit was selected to build power template.The analysis results showed the signal-to-noise ratio(SNR) power consumption increase of more than 20%after considering s-box's power consumption so that the information of keys can be obtained with just half number of power traces.In addition,the side channel-leakage detection capability of our method also shows better effectiveness that can identify the correct keys.

Presenilins as endoplasmic reticulum calcium leak channels and Alzheimer's disease pathogenesis

Alzheimer disease(AD) is the most common neurodegenerative disorder worldwide and is at present,incurable.The accumulation of toxic amyloid-beta(Aβ) peptide aggregates in AD brain is thought to trigger the extensive synaptic loss and neurodegeneration linked to cognitive decline,an idea that underlies the'amyloid hypothesis'of AD etiology in both the familal(FAD) and sporadic forms of the disease.Genetic mutations causing FAD also result in the dysregulation of neuronal calcium(Ca2+) handling and may contribute to AD pathogenesis,an idea termed the'calcium hypothesis'of AD.Mutations in presenilin proteins account for majority of FAD cases.Presenilins function as catalytic subunit ofγ-secretase involved in generation of Aβ peptide Recently,we discovered that presenilns function as low-conductance,passive ER Ca2+ leak channels,independent of γ-secretase activity.We further discovered that many FAD mutations in presenilins result in loss of ER Ca2+ leak function activity and Ca2+ overload in the ER.These results provided potential explanation for abnormal Ca2+ signaling observed in FAD cells with mutations in presenilns.Our latest work on studies of ER Ca2+ leak channel function of presenilins and implications of these findings for understanding AD pathogenesis are discussed in this article.

Relationship between the Flow Blockage of Tip Leakage Vortex and its Evolutionary Procedures inside the Rotor Passage of a Subsonic Axial Compressor

The near casing flow fields inside the rotor passage of a 1.5 stage axial compressor with different blade-loading levels and tip gap sizes were measured by using stereoscopic particle image velocimetry(SPIV). Based on a carefully defined blockage extracting method, the variations of blockage parameter inside the blade passage were analyzed. It was found that the variation of blockage parameter appeared as a non-monotonic behavior inside the blade passage in most cases. This non-monotonic behavior became much more remarkable as the blade loading increases or mass flow rate decreases.The variations of the blockage parameter inside the blade passage had close relation to the evolutionary procedures of the tip leakage vortex(TLV). The destabilization of the TLV caused a rapid increasing of the blockage parameter. After the TLV lost the features of a concentrated streamwise vortex,the blockage parameter usually got a peak value. And then, because of the intense turbulent mixing between the TLV low momentum flow and its surrounding flows, the flow deficit inside the TLV recovered.

Unsteady flow structures in the tip region for a centrifugal compressor impeller before rotating stall

To get an insight into the occurrence and the mechanism of flow unsteadiness in the tip region of centrifugal compressor impellers, the flow in Krain’s impeller is investigated by using both steady and unsteady RANS solver techniques. It is found that the flow unsteadiness on the pressure side is much stronger than that on the suction side. The periodical frequency of the unsteady flow is around half of the blade passing frequency. The originating mechanism of the flow unsteadiness is illustrated with the time-dependent tip leakage flow and blade loading at the tip region. Due to the blockage caused by the joint effects of broken-downed tip leakage vortex, separated fluids and tip leakage flow at downstream, a low pressure region is formed on the pressure side, consequently the blade loadings is altered. In turn, the changed blade loadings will alter the intensity of tip leakage flow. Such alternative behavior finally results in the periodic process. By comparing the calculated flow field in the cases of single-passage and four-passage models, it is confirmed that the investigated flow unsteadiness is confined in each single passage, as no phase differences are found in the model of four passages. This is different from the situation in axial compressor when the rotating instability is encountered. The flow unsteadiness only occurs at the working conditions with small mass flow rates, and the oscillation intensity will be enhanced with the decrease of mass flow rate. When the mass flow rate is too small, the flow unsteadiness in a single passage may trigger rotating stall, as the disturbance propagates in the circumferential direction.