表面改性空心微珠吸波涂层的制备及其吸波性能研究

为了研制低密度、低成本和高吸波性能的电磁波吸收材料,运用高压液相氢还原工艺对空心微珠粉体进行表面镀镍改性处理,并制备了表面改性空心微珠吸波涂层。经表面测试分析证明,表面改性后的空心微珠粉体表面形成了较好结晶程度的镍改性层,且随镀镍量的增加表面镍包覆层逐渐趋于完整。研究了表面改性空心微珠吸波涂层在8~18 GHz范围内的吸波性能,重点考察了镀镍量、粉体含量和涂层厚度对表面改性空心微珠涂层吸波性能的影响。研究结果表明:表面改性空心微珠粉体的镀镍量为50%,粉体含量为65%,涂层厚度为3 mm时涂层具有良好的吸波性能,最小反射率可达到-14.555 dB,对应的频率为9.817 GHz,小于-10 dB的吸收带宽为3.1 GHz.     

纳米复合双层雷达吸波涂层研究

采用等离子喷涂工艺制备纳米复合镍粉/羰基铁粉双层雷达吸波涂层,并研究涂层的吸波性能。结果表明,双层涂层的吸波性能明显优于单层涂层的吸波性能,涂层厚度为1mm时,吸波曲线在6～18GHz频段内的反射率低于-5dB,吸收峰值达到-17.96dB。     

化学镀层与涂层复合多层结构雷达波吸收性能研究

以纳米铁酸镍钴铁氧体复合Co粉、羰基铁粉等为吸收剂,并采用化学镀层,进行了单层、双层和三层涂层的试验研究。以期通过多层复合,获得既有良好的阻抗匹配同时又能对入射电磁波有效衰减的吸波涂层。采用纳米铁酸镍钴复合微米钴粉为吸收剂的单层雷达波吸波涂层;羰基铁粉与纳米铁酸镍钴复合微米钴粉的双层涂层,以及双层复合涂层+镀镍层的三层复合层结构,三种涂层厚度均为1mm,研究了三种涂层的吸波性能。结果表明,双层复合涂层的吸波性能较单层涂层在低频段有较大的提高,纳米铁酸镍钴复合微米Co的双层复合涂层的吸波性能优于纳米铁酸镍钴复合Co的单层涂层,三层复合涂层的吸波性能优于单层和两层复合涂层,三层复合涂层反射率小于-5dB的频宽为4.5～18GHz,较双层涂层提高5.4GHz。其中镀镍层对提高吸波性能作用明显。     

伪装网雷达吸波涂层的研制

采用化学镀或PVD的方法在基材沉积Ni金属层 ,Ni层与纳米晶金属粉涂层构成的复合涂层应用于三维伪装网时 ,该复合涂层具有厚度薄、面密度小、吸波频带宽、吸波性能好的特点 ,在 2～ 18GHz频率范围内最小反射率达到 - 18.2 4dB。     

铁氧体/羰基铁粉复合吸波材料研究

采用化学共沉淀法制备了W型六角晶系钡铁氧体,测试其在掺杂不同含量羰基铁粉后的电磁参数,利用传输线理论对电磁参数进行计算模拟,得到了2～18 GHz下该材料的平板反射率曲线,研究了羰基铁粉掺杂对铁氧体电磁特性的影响。结果表明:随羰基铁粉含量的增加,复合吸收剂在匹配厚度逐渐减小时,吸波效能逐渐增加。当铁氧体与羰基铁粉的质量比为10∶.3,样品的匹配厚度为2.4 mm时,涂层在该厚度下的理论吸收峰值为-61.88 dB,吸收率小于-10 dB的带宽达到7.48 GHz;涂层厚度为2 mm时的微波衰减能力仍能满足使用要求。掺杂后铁氧体的复数磁导率的频散效应的减弱是吸波性能显著改善的主要原因。     

低发射率涂层与超材料吸波体兼容性能的研究

采用添加炭黑阻抗匹配层的方法提高(8～14)μm波段低发射率涂层与超材料吸波体的兼容性。发射率由IR-2型发射率测试仪测试,用弓形法测量添加炭黑阻抗匹配层前后,低发射率涂料与超材料吸波体复合结构在(2～18)GHz频段的反射率损耗曲线。结果表明:涂覆低发射率涂层对超材料吸波体的吸波性能影响较大,(2～18)GHz频段的平均反射损耗衰减5.81 dB;-10 dB吸波带宽缩短4.2 GHz。在低发射率涂层与超材料基板之间添加炭黑匹配层后,复合涂层的发射率基本保持不变,但是提高了涂层与超材料的兼容性能,涂覆后(2～18)GHz频段的平均反射损耗仅减少2.16dB;-10 dB带宽仅减少3.16 GHz。     

涂料型吸波体的实用研究

以改进涂料型吸波体的厚度、粘度、带宽和厚度允许偏差为目的,开发出三种涂料型吸波体;1)在涂料中混入铁氧体粉末和镀镍云母的混合型。2)在涂料中混入表面镀镍的铁氧体粉末的电镀型。3)频带宽、厚度允许偏差大的宽带型。厚度分别为1.2mm、1.6mm和2.3mm。第3种的厚度允许偏差为±0.3mm,它是由防锈层、吸波体层和表面涂层构成的,实用评价试验结果得到了平均反射系数为-22.4dB的良好特性。可靠性(耐老化、盐水喷雾、风蚀、热冲击)试验证明吸波性能、物理性能和机械性能都符合要求。     

Fe-Co混合粉吸波涂层的制备及其性能研究

以脂肪族聚氨酯树脂为基体,添加微米级羰基铁粉、石墨为主要吸收剂,在主吸收剂中加入钴粉用以调节吸收剂的电磁参数,以分层喷涂的制备工艺制作了一种吸波涂层。通过对粉体样品电磁参数的对比测试,探讨了钴粉的加入对羰基铁粉电磁参数的影响,以期获得良好的阻抗匹配。分析钴粉在混合粉体中的含量对涂层反射率的影响,分层喷涂的制备工艺保证了涂层梯度结构的形成,通过设计不同分层的配方,使成品涂层表现为面层对电磁波的低反射,内部吸收层对电磁波的高吸收。制备的涂层厚为1.02 mm,面密度为2.73 kg/m2,反射率低于-10 dB的有效带宽为5.45 GHz,是一种轻质、高效的隐身涂层。     

一种基于精英策略非支配排序遗传算法-Ⅱ的多层吸波涂层结构设计方法

涂层结构设计是实现吸波涂层良好吸收性能的重要手段,利用计算机辅助进行结构设计成为研究趋势。针对当前涂层结构计算机辅助设计存在的运算效率低、优化目标单一、需人工干预等问题,构建了吸波涂层“宽、轻、薄、强”的多目标优化模型,设计了一种基于多目标遗传算法NSGA-Ⅱ的多层吸波涂层结构设计方法,给出了已知材料、已知涂层数下的最优涂层结构设计方案。经实际喷涂测试,采用3号和2号材料的双层吸波涂层经优化后的总厚度为0.6 mm,在18~18 GHz 波段的反射率均低于-8 dB. 试验验证表明,在保证一定预测冗余的情况下,该方法对雷达波吸收涂层的设计具有一定参考价值。     

改性羰基铁粉在红外/雷达兼容涂层中的应用

以羰基铁粉作为颜填料,聚氨酯作为树脂基体,制备雷达/红外兼容隐身单涂层,分析羰基铁粉的形态、含量以及球磨时间对涂层红外低发射率以及雷达吸波性能的影响。结果表明:未球磨时,颜填料质量分数为60%,涂层厚为2 mm,在18 GHz处其涂层反射率的最小值达-9.3 dB,其涂层的红外发射率为0.85;球磨16 h,羰基铁粉由球状变为片状,质量分数为60%,其涂层的红外发射率降低至0.69,雷达吸波性能略有降低。羰基铁粉有望成为红外/雷达兼容隐身材料。     

Nitrosation and Nitration of Tetraacetyldibenzylhexaazaisowurtzitane

Tetraacetyldibenzylhitane (TADBIW) was subjected to debenzylation by nitrosating with inorganic materials available commercially to synthesize tetraacetyldinitrosohexaazaisowurtzitane (TADNSIW). TADNSIW was purified, and its structure was determined by FTIR, 1H NMR, MS and element analysis. The debenzylation reaction of TADBIW gave quantitative benzaldehyde as a by-product. This indicates that the reaction produces an imine cation as an intermediate. Hexanitrohexaazaisowurtzitane (HNIW) was prepared from unpurified TADNSIW with the yield over 96.0 % and the purity more than 98.0 %. And the mechanism of the reaction from TADNSIW to HNIW is proposed to be oxidation of nitroso and nitration of acetyl on the molecule of TADNSIW, This reaction system involved is simple, and the reaction can complete within a short time and under mild conditions. The product can be easily to separate and the waste disposed readily.     

A Robust Algorithm for Watermarking 2D Vector Maps with Low Shape-Distortions

The technique of watermarking has been introduced into 2D vector maps for many potential applications such as protecting the copyright of important GIS （geographical information system） data and tracing the data source of military maps. In most previous works, although the validity of the map data could be preserved during the embedding procedure, the shape-distortions of the map elements are usually neglected which would tend to degrade the invisibility of the watermarking schemes. A shape-preserving algorithm for watermarking 2D vector maps is presented in this paper. A 1D distance sequence extracted from the original map is adopted as the cover data instead of 2D coordinates. A watermark bit is represented by changing the distributions of the cover data. The embedding procedure induces lower shape-distortions than in former works. Experimental results indicate better invisibility of the proposed scheme, as well as its robustness to certain attacks such as map simplification, interpolation, additive noise and most geometric transforms.     

Open Rule-setting System Applied to Conceptual Design of Engines

Open rule-setting method advanced in this paper concentrates on providing designers of engines with a convenient way to express their design innovations and develop the expected prototypes in the early CAD stage, and constitute effective models for the following analysis process of CAE and CAPP. The problems arisen in the process of conceptual design with the traditional experience-based development method are analyzed. Based on those analyses, open rule-setting method is presented and some associated technical problems are discussed. The functional framework of open rule-setting system was built as software engineering methods. The speciality of the engine product as a kind of complex product and the requirement of the engine product based on its structural particularity to rule-setting system are considered carefully. A demonstration is supplied to illustrate how the open rule-setting method enhances the efficiency and quality of the engine conceptual design.     

Research on Linux Network Device Driver

By analyzing the working principle of Linux network device driver, discussing the Linux network driver structure and its key technologies, the general network driver structure and its design methodologies in Linux system are summarized. Through modifying the network device driver of Linux device driver 3rd version snull, c and improving the COW technology, the Zero-Copy technology in Linux （kernel version 2.6.11 ） is implemented. In the end, the success test tells us that the thorough analysis of network device driver is the foundation of many applications, and it also provides a certain improvement to a lot of real applications, even to military application development.     

Improvement and Experiment of the Reamer in Vibra Cutter Against Wave Edge of Titanium Sheet Alloy Parts

By analyzing the influencing factors of part quality making of sheet alloy of titanium by vibra cutter, the shape of upper reamer is set as cylinder and wedge-shaped form, and the lower reamer as plain and hemicycle form, and its main structural parameters are defined as well. Then it is validated further that such improved vibra cutter reamer can be used to process curve-edged parts of titanium alloy sheet. The experimental result shows that the titanium alloy sheet parts processed by above equipment have no sharpen angles for convex parts and evident crevasse of concave-edged part. In summary, such improvement can eliminate the free-waved edge and improve the manufacture quality of titanium alloy sheet parts greatly.     

Experimental Study on the Small Flyer Initiating Behavior of Fine-grained Explosives

The initiating behavior of fine-grained explosives by small flyer is studied. The diameter of small flyer in this device is 1 ram. The test results indicate that the granularity of explosives has great effect on its flyer initiating sensitivity.The flyer initiating sensitivity of the fine-grained explosives is higher and the critical initiating energy is lower than that of common explosives. For common explosive, the flyer initiating sensitivity increases as the density is reduced. But for the fine-grained explosive, the test results are exactly opposite.     

Algorithm for Multi-laser-target Tracking Based on Clustering Fusion

Multi-laser-target tracking is an important subject in the field of signal processing of laser warners. A clustering method is applied to the measurement of laser warner, and the space-time fusion for measurements in the same cluster is accomplished. Real-time tracking of multi-laser-target and real-time picking of multi-laser-signal are introduced using data fusion of the measurements. A prototype device of the algorithm is built up. The results of experiments show that the algorithm is very effective.     

Influence of Installing Error on the Surface Shape Precision of the Axial Symmetry Aspheric Workpiece in Lapping

A method to calculate the surface shape error, which is caused by the installing error between the workpiece and the lapping tool in the process of form lapping, is proposed. The mathematical model which the installing translation error influences on the workpiece surface shape error is established. The changing rule of the error is simulated through the calculating example of the paraboloid workpiece. The results indicate that the surface shape error of the workpiece is increasing with the increase of the installing translation error, it is also increasing gradually along the center point of the curve surface to the edge, and the influence is severer to the curve surface with great curvature than that of the small curvature when the translation error is the same.     

Experimental Research on Output Performances of Giant Magnetostrictive Actuator

The paper introduces the performances of magnetostrictive actuators and its applications, discusses the design methods for the structure and internal magnetic circuit of a giant magnetostrictive actuator, and makes tests on the output displacement and force characteristics for an actuator using homemade magnetostrictive material. The experimental result shows that the actuator has satisfactory output precisions and ranges in transient and stable states, and can be used in lowfrequency vibration control system of precise equipment.     

Robust Graded Sliding Mode Tracking Control for Low Speed Spinning Ballistic Missiles

The nonlinear dynamic model of spinning ballistic missiles is established during the first boosting phase of the missile. Based on the conventional backstepping sliding mode control and the assumption of a two time-scale separation of missile dynamics, a graded sliding mode controller is designed with two sub-sliding surfaces which have invariability to external disturbances and parameter perturbations, and a matrix which comprises three first order low pass filters is introduced to prevent ＂explosion of terms＂. Owing to the upper bounds of the uncertainties are difficult to obtain in advance, adaptive laws are introduced to estimate the values of the uncertainties in real-time. Eventually, the numerical simulation results given to show the proposed controller can ensure the steady flight of missiles.