敷设某种吸声材料的声诱饵简化模型隔离度仿真计算

随着水声电子对抗技术的不断发展,对于声诱饵系统边收边发技术的需求日益增强。实现边收边发技术的难点之一在于如何增大声诱饵系统发射端与接收端的隔离度。由于高分子吸声材料对声能的吸收作用,可以考虑采用在声诱饵接收端敷设吸声材料的方式,对声诱饵系统的隔离度进行改善。利用有限元计算软件对简化的声诱饵模型的隔离度进行数值仿真计算,分析声诱饵模型接收端敷设不同厚度的吸声材料时,对声诱饵系统隔离度的影响。计算结果表明,在声诱饵接收端敷设吸声材料时,可以增大声诱饵系统发射端与接收端的隔离度;当吸声材料达到一定厚度以后,对声诱饵系统隔离度的影响几乎不变。     

悬浮式矢量边发、边收声诱饵关键技术

现代＂智能＂鱼雷的一种对抗手段是发射诱骗编码寻的信号,因此需要相应发展＂智能＂的对抗器材。边发、边收声诱饵在发射应答信号时,不关闭接收机,从而可以不受诱骗编码的欺骗,在发射强干扰的同时测量鱼雷寻的信号的频率,来控制发射频率自动跟踪鱼雷寻的频率的变化,增强声诱饵的对抗能力。对于悬浮式声诱饵,边发、边收的关键技术是抗发射声串漏、界面反射声及混响的干扰。讨论了悬浮式矢量边发、边收声诱饵的组成和信号处理方法,利用矢量传感器的零点指向性抑制强干扰,可以使诱饵发射时也能探测微弱的寻的信号,并能测量鱼雷寻的信号的频率。     

一种上半空间指向性的水声发射换能器结构设计

本文讨论了一种具有上半空间指向性的水声发射换能器的结构,采用半液腔压电圆管换能器实现了上半空间指向性,在换能器结构中采用吸声锥形障板加反声障柱的方法,实现换能器的垂直向上的窄波束指向性。同时也提高了测量装备在边收边发方式下的声隔离度,有效抑制了收发换能器间的声串漏。通过对实物测试,系统声学收发隔离效果达到35d B以上,该换能器结构设计的有效性得到了验证,并将在装备研制中得到应用。     

一种新型声隔离系统

水声换能器的收／发声隔离度决定了很多水声设备的性能优劣。介绍了一种新型声学隔离系统,该系统改变了声障板的设计思路,使换能器的收／发声串漏得到明显降低。通过偶极子原理,提出了一种提高收／发声学隔离度的方案。利用有限元仿真手段,计算并验证了该种方案的有效性。参照仿真模型,制作了一套声隔离系统样机,在1个倍频程的频带内,该系统的收／发声隔离度大于40dB。该声隔离系统提高了现有水下声目标模拟设备的性能。     

宽带水声参量阵指向性设计与实验验证

利用宽带水声参量阵可产生高指向性宽带低频声束,推导了宽带水声参量阵生成低频声束的自解调理论模型,对其换能器指向性进行了分析与设计,并研制出了宽带水声参量阵样机。测试结果表明：该样机产成的2 kHz声束的-3 dB指向性锐角约为2.6°,具有很好的指向性,且旁瓣抑制效果好,能够产生无旁瓣的高指向性低频声束。这为解决浅海水声通信的多途干扰、远程水声保密通信等问题提供了一条新思路。     

二阶镶拼圆管矢量接收换能器研究

文章介绍了一种二阶镶拼圆管矢量接收换能器的设计方法，获得了类偶极子指向性以及波束宽度更为锐化的类四极子指向性。利用理论计算以及有限元仿真分析了镶拼圆管的指向性以及接收灵敏度，并实际制作了二阶镶拼圆管矢量接收换能器。在消声水池的测试表明，灵敏度测试结果与有限元仿真计算结果吻合较好，镶拼圆管矢量接收换能器类偶极子指向性图-3 dB波束宽度在95°左右，类四极子指向性图-3 dB波束宽度在40°左右，二阶矢量指向性图波束宽度明显比一阶矢量指向性图波束宽度更加锐化。     

互易法校准压电型声发射传感器的研究与实现

声发射传感器的校准是实现声发射定量技术的前提,依据电声换能器互易原理,在计算互易常数的基础 上,建立了适用于压电型声发射传感器表面波和纵波互易的校准系统。通过设置特定的激励信号波形,依据接收 电压信号与激励电流信号之间的时间延迟,准确获取电流信号与电压信号对应的特征值,实现了声发射传感器的表面波和纵波互易校准。由于传感器的尺寸效应,传感器在高频时的表面波速度灵敏度低于纵波灵敏度,不确定度评定结果表明,声发射传感器速度灵敏度的互易法校准不确定度为1. 2 dB。     

征稿简则

1《声学与电子工程》系国家正式批准出版的全国性技术刊物,刊号为CN33-1099/TN。本刊主要报道水声、超声领域的应用研究成果,涉及声呐系统、水声发射、信号接收与处理、信息显示、系统结构与控制、声学材料、换能器与声阵、水声测试、计算机技术和超声应用等声学与电子技术;内容包括理论探讨、工程     

征稿简则

1《声学与电子工程》系国家正式批准出版的全国性技术刊物,刊号为CN33-1099/TN。本刊主要报道水声、超声领域的应用研究成果,涉及声呐系统、水声发射、信号接收与处理、信息显示、系统结构与控制、声学材料、换能器与声阵、水声测试、计算机技术和超声应用等声学与电子技术;内容包括理论探讨、工程设计、技术应用、科学实验、技术综述和科技动态等。它可作为研究、生产、教学、情报单位、有关业     

征稿简则

1《声学与电子工程》系国家正式批准出版的全国性技术刊物,刊号为CN33-1099/TN。本刊主要报道水声、超声领域的应用研究成果,涉及声呐系统、水声发射、信号接收与处理、信息显示、系统结构与控制、声学材料、换能器与声阵、水声测试、计算机技术和超声应用等声学与电子技术;内容包括理论探讨、工程设计、技术应用、科学实验、技术综述和科技动态等。它可作为研究、生产、教学、情报单位、有关业     

Effect of Permeable Crystalline Material on Steel Reinforcement Corrosion of Concrete

Permeable crystalline materialcan permeate into pores and cracks of concrete and catalyze the reaction between Ca(OH) 2and unhydrated cement to generate a great quantity needle non-soluble crystals, which can stop up the pores and cracks of concrete, and increase the impermeability of concrete. This paper reported the results of a study conducted to evaluate steel reinforcement corrosion of concrete specimens uncoated and coated with permeable crystalline material as well as mixed with the permeable crystalline material. The properties evaluated for corrosion test were water impermeability, water absorption, compressive strength and potential. The results of water impermeability, water absorption, compressive strength clearly showed that the permeable crystalline material could prohibit water, any soluble salts and moisture from penetrating the concrete to cause corrosion, leaking, and other problems, and it did increase the compressive strength, which was favorable for protection of corrosion of reinforcing steel. Moreover, it was concluded from the potential-time curve that the steel reinforcement of uncoated specimen was in the state of activation whereas that of other specimens coated and mixed with the permeable crystalline material was in the state of inactivation. Above all, it was indicated that the permeable crystalline materialis very effective to protect the steel reinforcement of concrete from corrosion.     

The Research and Application About "Dry Peeling Off" Technology for Airplane Surface Paint Layer

In this paper, the principle of spurting take off lacquer were introduced; and with orthogonal method the unsaturate polyester was prepared ;it was easy to peel airplane paint layer off with this material and equipment.     

Quality Study of Honeycomb Core Shaping Without Wax Stabilization

Sandwich panels utilizing honeycomb cores result in lightweight, high-strength units that are very rigid. Indeed, they give honeycomb panels the best strength-to-weight ratio of any construction type available. Conventionally, the wax is poured into the cell of the core to strengthen the structure and prevent the core from being crushed during milling. Much time and labor is required to wax, mill, and clean the cores. In this study, the process of pouring wax into the core was skipped. In other words, the cutter directly milled the core. Experiments showed that the compressive strength of the core produced without wax stabilization was only 3% lower than that of cores produced using the traditional method. In addition, the drum peel strengths of cores produced without wax stabilization were 38.4% higher than cores produced using the traditional method, in which residual wax seriously polluted the adhesive. It was also found that eliminating the wax process can reduce costs.     

In-process thermal treatment of polylactic acid in fused deposition modelling

Polylactic acid (PLA) is one of the most widely used open source fused filament fabrication materials due to its ease of extrusion, biodegradability, and mechanical strength. The mechanical strength of PLA largely depends on the proper growth of its semi-crystalline structure, which can be severely impaired by a low rate of crystallization, particularly in open source printers. This can be further aggravated by the non-uniform thermal distribution of heat that causes improper curing among the extruded beads of the printing material. As a result, PLA printed on open source printers does not achieve the best mechanical properties. This research, for the first time, proposes an additive-free solution implemented through a detailed set of experimentation to improve the curing rate through in-process temperature variations to cure the joints among the beads. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy is used to confirm the improvements in the bead joints. This work is conducted in two phases of experiments. In the first phase, a full factorial ANOVA is used to investigate various process parameters and the important variables are used in the second phase to print test specimens in four different sets.     

Investigation of the Corrosion Behaviors of HVOF-Sprayed Carbide Cernet Coatings in Molten Al-Zn-Si Alloy Bath

In continuous hot-dip galvanization process the corrosion and chemical stability of the sink roll in the galvanizing bath are important problem which effects on the quality and productivity. In order to protect the sink roll the carbide cermet and/or ceramic coatings were deposited on the surface of the sink roll. The WC-, Cr3 C2-cermet coatings were deposited by high velocity oxygen fuel (HVOF) spray, respectively. The coating samples were immersed in molten Zn-alloy containing 50 wt % aluminum at 833 K for 24 hr and 144 hr, respectively. The inter-diffusion and inter-reaction of Zn, Al and elements in coating and corrosion behaviors of these coatings were investigated by XRD, SEM and EPMA etc. The corrosion mechanisms of the carbide cermet coatings and ceramic coatings in molten High Al-Zn-alloy were approached.     

Fundamental study of adhesion of ice to cooling solid surface (Discussion on influence of copper oxide layer on ice adhesion force)

In many situations, ice often adheres to a cooling solid surface, frequently causing serious accidents. It is critical to clarify the mechanism of ice adhesion to the cooling surface in order to prevent ice adhesion. In a past study, the shearing stresses of two kinds of test plates with a copper surface having the higher thermal conductivity were measured. The shearing stress corresponds to ice adhesion force. Both shearing stresses were significantly different; however, the cause remains unclear.Therefore, the present study focuses on an oxide layer as the main factor causing the difference of both shearing stresses; the influence of the oxide layer formed on shearing stress was discussed. And in the removal and reformation processes of the oxide layer, the time variation of the shearing stress was clarified. Moreover, the relationship between the state of the copper surface and the shearing stress was also clarified by surface analysis.     

重塑标准推行格局 推动LED照明的普及（英文）

正When you are enjoying the green,energy-saving and healthy lighting of IKEA LED luminaire,you may not realize that most of IKEA’s LED bulbs are produced by the LED luminaire smart manufacturing system of Hangzhou Zhongwei Photoelectricity CO.,LTD(ZVISION).No longer enclosed in the laboratory,the product standards are brought into the factory workshop and even to the entire production process.Thus,the standards are promoted and applied in a favorable way by enterprises,benefitting consumers with high quality products.     

Chinese Experts Contribute to ISO＇s New Toy Standards

正The international standard,ISO 8124-6,Safety of toys–Part 6:Certain phthalate esters in toys and children’s products,was officially issued by ISO worldwide on August 15.It was the first time for Chinese experts to lead the ISO standard development in toys industry.The standard was drafted by a group of Chinese experts from SAC/TC for toys and relevant Chinese departments and finally completed by a dedicated international group of experts.ISO 8124-6 makes a substantive breakthrough in the aspects of the scope of toys,limitation of plasticizer types,control of test cost,accuracy of test,operation convenience,etc.,offering the operational guidance for toy manufactures and testing laboratories.     

中国质量(北京)大会(英文)

正Themed on"quality,innovation,development",the first China Quality Conference(Beijing)was held in the Great Hall of the People on September 15.Chinese Premier Li Keqiang delivered an important speech at the conference.State Councilor Yang Jing and Wang Yong attended the conference with over 600 domestic and international representatives from foreign,regional and international quality organizations     

National Working Meeting on Land and Resources Standardization

正The National Working Meeting on Land and Resources Standardization was held in Beijing on July 15,2014.Wang Min,the Deputy-Minister of the Ministry of Land and Resources,and Yin Minghan,the Chief-Engineer of SAC addressed the meeting.Representatives from relevant competent departments and technical committees were present.The meeting aims to summarize work,discuss existing problems and make clear working thoughts,promoting standardization work of land and resources to a new level.Wang Min pointed out that the standardization work of land and resources should be centered on the basic principles of"protecting land and resources dutifully,intensively and economically utilizing land and resources,and making all-out efforts to safeguard the public’s rights and interests",highlighted the