基于十字形阵列和2D-MUSIC算法的Lamb波检测

采用由压电传感器组成的十字形阵列进行Lamb波信号的激励和接收，提出一种二维多重信号分类（2D-MUSIC）方法对铝板中的缺陷进行定位检测。选用合适的频率激励产生单一模态信号，可避免多模态的影响，降低Lamb波的频散；利用2D-MUSIC算法对接收信号进行分段处理，并结合反射信号和二维导向矢量对铝板中的缺陷进行定位。结果表明，提出的2D-MUSIC算法对铝板中的缺陷定位比传统MUSIC算法更精准。     

Application of intensive hydrodynamic cavitation in liquids for synthesis of hydrogen and nanoparticles

In this paper, the results of experimental studies of hydrogen and nanoparticles production using intensive hydrodynamic cavitation in liquids are presented. Physicochemical processes occurring in a cavitation bubble at the last stage of its compression are very similar to processes occurring in the explosion chamber.The values of pressure and temperature achieved in this case ensure the thermodynamic stability of the reaction products and the production of a gaseous hydrogen and nanoclusters as a result of decomposition of molecules of liquid, which is confirmed by theoretical calculations.The controlled addition of hydrogen-containing liquids and the change in the compression conditions of cavitation bubbles make it possible to control the process of hydrogen synthesis, which is an important step in the development of modern high-tech alternative energy methods.The pulsation of a spherical cavity is described by the Kirkwood – Bethe equations, which are one of the most accurate mathematical models of pulsation processes at an arbitrary velocity of the cavity boundary. The model allows to describe the process of pulsations of cavitation cavities, conduct comprehensive parametric studies and evaluate the effect of various process parameters on the collapse of cavities.This work continues with the experiments on cavitation synthesis of carbon nanostructures. With the rapid movement of chemically pure hydrocarbons along the profiled channel in the form of a Venturi nozzle, cavitation bubbles form in the liquid, which are then compressed in the working chamber, in which a sharp pressure surge is created. The pressure in the shock wave, which reaches 80–90 MPa, ensures the collapse of cavitation bubbles close to adiabatic compression. As a result of the number of rapidly occurring physicochemical processes of evaporation, heating, and thermal dissociation of hydrocarbon vapors, a solid carbon phase including graphene oxide nanoparticles and a gaseous hydrogen-containing phase are synthesized in the cavitation, which is then subjected to separation. Synthesized graphene oxide nanoparticles possess activated surface due to the cavitation action and can be subsequently used as substrates for modification with functional nanoparticles, e.g. silver nanoparticles with antibacterial properties.The article is of great help to scientists and design engineers who are engaged in the development of promising hydrogen generating facilities and hydrogen complexes.     

Simulation of interaction between high-temperature process and heat emission from electricity system in summer

During the hot summer season, using electricity systems increases the local anthropogenic heat emission, further increasing the temperature. Regarding anthropogenic heat sources, electric energy consumption, heat generation, indoor and outdoor heat transfer, and exchange in buildings play a critical role in the change in the urban thermal environment. Therefore, the Weather Research and Forecasting (WRF) Model was applied in this study to investigate the heat generation from an indoor electricity system and its influence on the outdoor thermal environment. Through the building effect parameterization (BEP) of a multistorey urban canopy scheme, a building energy model (BEM) to increase the influence of indoor air conditioning on the electricity consumption system was proposed. In other words, the BEP+BEM urban canopy parameterization scheme was set. High temperatures and a summer heat wave were simulated as the background weather. The results show that using the BEP+BEM parameterization scheme of indoor and outdoor energy exchange in the WRF model can better simulate the air temperature near the surface layer on a sunny summer. During the day, the turning on the air conditioning and other electrical systems have no obvious effect on the air temperature near the surface layer in the city, whereas at night, the air temperature generally increases by 0.6 ℃, especially in densely populated areas, with a maximum temperature rise of approximately 1.2 ℃ from 22:00 to 23:00. When the indoor air conditioning target temperature is adjusted to 25–27 ℃, the total energy release of the air conditioning system is reduced by 12.66%, and the temperature drops the most from 13:00 to 16:00, with an average of approximately 1 ℃. Further, the denser the building is, the greater the temperature drop.     

爆炸能分配比值对爆炸应力波峰值的影响

为评价膨胀能Ｅｂ在破岩过程中的作用，进行了爆炸应力波的测定实验，研究了冲击能（Ｅｓ）与膨胀能（Ｅｂ）分配比值的变化对爆炸应力波峰值的影响。实验结果表明，随着Ｅｓ／Ｅｂ比值的增大，原生爆炸应力波的峰值随之增大，而次生爆炸应力波的峰值则相应减小。     

爆炸冲击能和膨胀能破岩作用机理研究

为研究岩石破碎过程中爆炸应力波与爆生气体膨胀的作用，进行了耦合装药爆破实验。结果表明，耦合装药爆破时爆炸冲击能（Ｅｓ）和部分膨胀能（Ｅｂ）进行冲击加载，在介质中依次激起原生和次生爆炸应力波。不同Ｅｓ／Ｅｂ比值条件下，介质爆破致裂效果与破碎质量出现明显差异的主要原因，是这两个应力波加载水平发生了变化，进而影响到介质的爆破破裂行为。由此认为，Ｅｓ和部分Ｅｂ在破岩过程中所起的主要作用，是通过应力波与缺陷相互作用使岩石产生破裂的方式进行的；以（准）静态形式存在的部分Ｅｂ的主要作用，是促使爆破块度与岩体分离。     

示波器在炸药压力减敏研究中的应用

将示波器运用到炸药动压下的减敏研究中，通过测量减敏前后水中冲击波，将炸药的减敏程度数量化，克服了以往实验手段只能用拒爆、半爆等概念定性描述的不足，为进一步研究炸药的减敏机理提供了有效手段．研究表明，乳化炸药动压下的减敏程度随着受压距离的增加而呈线性下降趋势，从发生减敏到被压死是一个连续过程而没有一个明确的界限．     

900 MHz无线电波在地下长壁煤矿的传播

给出了900MHz无线电波在两个地下煤矿采煤工作区的测量结果,并有混合传播模型解释以上结果,得到的结论为：在巷道中,传播区域被转折点分为两段,在转折点前面,接收信号电平在42m内下降27dB;而在转折点之后,接收信号电平下降得很缓慢,胶带巷道和车辆巷道中衰减分别为13．3dB/100m,(6.75＋10)dB/100m,在采煤区进风巷中,传播损耗为22dB/100m,标准偏差为1．75dB;在采煤区长壁工作面上,传播衰减率均为75dB/100m,标准偏差小于2.2dB,在井下可以采用微蜂窝无线通信系统。     

Features of forming an explosive fracture zone in a hard rock mass

The effect of extended discontinuities in a hard rock mass on regularities of forming explosive fracture zones is considered. The comparison of the numerical and in situ experimental results permits to conclude that, in common with the known effect of seismic blast wave screenage, transformation of the wavefront configuration is of drastic importance. In a number of cases, that results in the generation of complex-structured fracture zones: new fractured zones can form beyond unbroken areas. It is demonstrated that the similar effects may cause redistribution of the blast energy and, as a consequence, the higher seismic efficiency produced by flat charge blasting as compared with concentrated charge blasting. __________ Translated from Fiziko-Tekhnicheskie Problemy Razrabotki Poleznykh Iskopaemykh, No. 3, pp. 65–76, May–June, 2007.     

基于声弹理论的地应力超声测量方法

首先描述岩石的声弹理论,给出岩石的应力与弹性波波速之间的理论关系;其次利用岩石应力与弹性波波速之间的理论关系提出地应力超声测量方法,即通过测量套孔应力解除前后的孔壁超声波波速的变化,利用声弹理论反演出地应力。通过数值算例讨论地应力对孔壁超声波速的影响,其结果表明,该方法可以有效地确定地应力的大小和方向。     

Impact of adaptive comfort criteria and heat waves on optimal building thermal mass control

This article investigates building thermal mass control of commercial buildings to reduce utility costs with a particular emphasis on the individual impacts of both adaptive comfort criteria and of heat waves. Recent changes in international standards on thermal comfort for indoor environments allow for adaptation to the weather development as manifested in comfort criteria prEN 15251.2005 and NPR-CR 1752.2005 relative to the non-adaptive comfort criterion ISO 7730.2003. Furthermore, since extreme weather patterns tend to occur more frequently, even in moderate climate zones, it is of interest how a building's passive thermal storage inventory responds to prolonged heat waves. The individual and compounded effects of adaptive comfort criteria and heat waves on the conventional and optimal operation of a prototypical office building are investigated for the particularly hot month of August 2003 in Freiburg, Germany. It is found that operating commercial buildings using adaptive comfort criteria strongly reduces total cooling loads and associated building systems energy consumption under conventional and building thermal mass control. In the case of conventional control, total operating cost reductions follow the cooling loads reductions closely. Conversely, the use of adaptive comfort criteria under optimal building thermal mass control leads to both lower and slightly higher absolute operating costs compared to the optimal costs for the non-adaptive ISO 7730. While heat waves strongly affect the peak cooling loads under both conventional and optimal building thermal mass control, total cooling loads, building energy consumption and costs are only weakly affected for both control modes. Passive cooling under cost-optimal control, while achieving significant total cost reductions of up to 13%, is associated with total energy penalties on the order of 1–3% relative to conventional nighttime setup control. Thus, building thermal mass control defends its cost saving potential under optimal control in the presence of adaptive comfort criteria and heat waves.