大型双板导波天线对核电磁脉冲传输损耗和畸变特性

大型导波核电磁脉冲模拟器可为系统级装备试验提供自由空间辐照环境。针对此类模拟器常用的双板导波天线可能存在的传输损耗和波形畸变问题,以电磁仿真软件和算例对比分析研究了3种主要的影响因素,包括土壤的介电损耗及其抑制、前锥板向平行板转折的结构不连续、线栅阵列代替金属板的缝隙泄漏。研究结果表明:对上下极板等宽的情形,土壤损耗可使电压传输效率降低25%以上;适当展开下极板宽度可屏蔽土壤损耗;上极板转折处的结构不连续可导致平行段试验空间内电场呈现双峰交叠、幅度降低、波形畸变等特征;最大线间距0.3 m不会导致前沿显著变化。作为工程应用案例,设计了前锥长度60 m、顶高15 m、下极板拓宽3 m、由100根线栅阵列构成上极板的导波天线,试验空间超过20 m×20 m×10 m,实现了前沿2.5~3.0 ns双指数脉冲的无损耗、无畸变传输。

铝加工行业中的金属损失及其控制措施

文章较为系统的描述了影响金属损失的各种因素,找到了能够合理降低金属损失的多种方法,对企业降本增效有一定的指导意义。

施苯菌灵抑制丛枝菌根真菌对污染土壤-玉米系统镉迁移的影响

为探讨土壤丛枝菌根真菌(Arbuscular mycorrhizal fungi,AMF)对污染土壤–作物系统Cd迁移行为的影响,采用云南兰坪铅锌矿周边重金属污染的土壤,开展室内试验,施杀真菌剂(苯菌灵)特异性抑制土壤土著AMF,研究抑制AMF对玉米生长、Cd含量与累积量、土壤Cd淋溶流失的影响。结果表明:(1)施苯菌灵显著抑制土壤AMF生长,导致AMF侵染率、孢子数、土壤球囊霉素相关蛋白(Glomalin related soil protein,GRSP)含量显著降低;并显著影响玉米生长与矿质营养,玉米地上部生物量、叶绿素与磷含量增加,而地上部氮钾含量降低。(2)施苯菌灵促进Cd向玉米根部和地上部迁移,主要富集在玉米地上部,导致玉米地上部的Cd含量和累积量显著增加。(3)施苯菌灵导致10cm和20cm壤中流的Cd浓度显著增加。此外,土壤GRSP含量与玉米地上部Cd累积量和壤中流的Cd流失浓度均呈极显著负相关。研究结果表明,土壤土著AMF有助于抑制土壤Cd向植株地上部迁移,减少壤中流Cd的流失浓度,降低污染土壤–作物系统Cd的环境迁移。

一种复杂多金属硫化矿中硫精矿再选优化工艺

由于某多金属铅锌矿选厂脱硫一步扫尾(硫精矿)金属损失严重,脱硫二步作业流程产出的铅锌精矿2品位较低,与分离产出的铅锌精矿1混合拉低了总铅锌精矿品位。为解决这一问题,提高混合铅锌品位,脱硫一步扫尾再浮选,实验室以脱硫粗一扫尾为原矿,脱硫二步开展氧化钙、硫酸铜药剂用量试验,进一步优化脱硫二步粗、扫选工艺。铅锌2改造为活流程的方案(高原矿时铅锌2直接进入铅锌精矿,低原矿时返回脱硫一步精选作业),降低硫精矿中Cu、Pb、Zn的品位,减少金属损失,提高回收率。

某大型斑岩铜矿选矿金属平衡影响因素分析

金属平衡是一项综合性管理工作,是衡量选厂生产、技术和经营管理水平的重要标志。影响金属平衡的因素有计量、取制样、检测化验、金属流失及中间产品积存等。本文将分析影响理论生产量与实际生产量金属平衡的各个因素,从而提高选厂金属平衡管理工作,更真实的反映出生产技术水平。

不同金属离子条件下微生物对聚合物溶液黏度的影响及作用机制

为了减少采油过程中因为金属离子导致的聚合物黏损,从而提高原油采收率,利用从大庆油田腐蚀管道筛选出的降黏菌S,通过向聚合物培养基中添加不同种类及浓度的金属离子,将降黏菌S对聚合物黏度的影响及作用机制进行了研究。结果表明:在2 000 mg/L的聚合物质量浓度下,向基础降黏培养基中加入10~50 mg/L的金属离子,Mn^(2+)、Fe^(2+)和Fe^(3+)的加入可以很大程度地提高降黏菌S的降黏率,最高黏损率分别为38.3%、35.6%、34.7%;K~+的加入对降黏菌S的降黏率影响不大;Cu^(2+)、Zn^(2+)的加入会降低菌S所引起的黏损;因此要控制采油体系中Mn^(2+)、Fe^(2+)和Fe^(3+)的含量,从而降低聚合物黏损;K~+离子含量也不宜太多。适当增加采油体系中Zn^(2+)、Cu^(2+),减少聚合物黏损,或者将6种离子均以质量浓度30 mg/L混合加入会降低聚合物黏损。研究成果对油田减少聚合物黏损,提高原油采收率提供了一定的方法和理论支撑。

1-苯基-3-(1-环己胺)-丙烯Schiff碱缓蚀剂在盐酸溶液中对J55钢的缓蚀效果

为改善酸化压裂施工造成的腐蚀问题,以肉桂醛和环己胺为原料合成了Schiff碱酸化缓蚀剂1-苯基-3-(1-环己胺)-丙烯(PCP),通过红外光谱和气相色谱-质谱联用对其结构进行表征,并采用失重法、电化学(极化曲线、阻抗谱、噪声)及分子动力学模拟等方法评价了PCP的缓蚀效果。结果表明,合成产物即为目标产物PCP。在15%HCl、90℃的条件下,随着PCP浓度增加,J55钢的失重腐蚀速率及腐蚀电流密度显著减小,缓释率逐渐增大。不同PCP加量下的缓释率均可达到99%以上,缓蚀效果较好。在PCP加量达到0.15%时,腐蚀速率及缓释率随着缓蚀剂浓度的增加整体变化不大,即缓蚀剂在J55钢表面的吸附浓度已达到临界胶束浓度,吸附量不再发生变化。PCP同时抑制了阴极析氢和阳极溶解反应,为混合型缓蚀剂。随着PCP浓度的增加,容抗弧半径、极化电阻及噪声电阻由小到大的排序均为:空白﹤0.05%﹤0.10%﹤0.15%﹤0.20%;低频的白噪声水平在电流PSD图中随着PCP浓度的增加而减小,即J55钢的腐蚀速率不断减小,与失重法及极化曲线反应的规律一致。当PCP分子与金属发生吸附并达到平衡时,整个缓蚀剂分子处于同一平面,平行吸附在J55钢表面,达到完全覆盖,从而有效减缓了腐蚀介质的侵入。

基于PCB线圈的钢丝绳金属横截面积损失检测方法

钢丝绳金属横截面积损失(Loss of Metallic area)直接影响钢丝绳承载强度等特性,因此其检测及定量分析对于设备安全可靠运行具有重要意义。针对目前主磁通检测中存在的线圈绕制困难、参数确定模糊等问题,基于仿真模型提出一种基于印制电路板(Printed Circuit Board)的分体式线圈结构,分析了线圈匝数、线圈层数、线距等参数对检测信号的影响;建立主磁通检测模型,探究损伤宽度对主磁通检测信号的影响规律,并针对损伤宽度变化造成的信号损失设计补偿方法;最后通过钢丝实验验证金属横截面积定量检测效果,表明该方法定量误差在1%以内,能够有效检测钢丝绳的LMA。

MOFs衍生的多孔材料Co/C的吸波性能研究

以金属有机配合物[Co(tza)_(2)]n为前驱体,采用防爆反应釜高温煅烧法分别在不同温度下制备得到碳复合材料Co/C,研究了它们的组分、电磁参数和吸波性能。结果表明:Co/C与石蜡以质量比1∶1混合后,450℃下获得的多孔纳米碳复合吸波剂Co/C-450的吸波性能最好,在厚度1.5mm处,有效吸收带宽为4.2GHz。此外,在0~18GHz和1.0~5.5mm的范围内,Co/C-450的总有效吸收带宽为13.3GHz(4.7~18GHz),实现了雷达多频段的有效吸收。复合材料良好的吸波性能是由于磁性Co纳米粒子和碳材料的协同作用,以介电损耗机制为主,实现对电磁波的有效吸收。不仅丰富了MOFs衍生物的吸波性能调控研究和结构设计,还为碳复合材料的轻质宽频研究提供了新思路。

Ingredient Losses during Melting Binary Ni-Ti Shape Memory Alloys

Losses of the alloying elements during vacuum induction melting of the binary NiTi alloys were evaluated by visual observation and chemical analysis of the NiTi melted specimens and the scalp formed on the internal surface of the crucible. The results indicated that the major sources of the losses were （a） evaporation of the metals, （b） formation of the NiTi scalp and （c） the sprinkling drops splashed out of the melt due to the exothermic reactions occurring between Ni and Ti to form the NiTi parent phase. Quantitative evaluations were made for the metallic losses by holding the molten alloy for 0.5, 3, 5, 10 and 15 min at around 100℃ above the melting point inside the crucible.Chemical analysis showed that there existed an optimum holding time of 3 min during which the alloying elements were only dropped to a predictable limit. Microstructure, chemical composition, shape memory and mechanical properties of the cast metal ingots were determined to indicate the appropriate achievements with the specified 3 min optimum holding time.

不同有机物料对滩涂盐碱地有机碳损失·重金属含量及水稻产量的影响

通过田间小区试验,研究不同有机物料(对照CK、鸡粪T_(1)、羊粪T_(2)、菌菇渣T_(3)、生物腐植酸T_(4))在等有机碳投入量下滩涂盐碱地中有机碳损失、土壤各类有机质分布及其对土壤重金属含量及水稻产量的影响。结果表明,不同有机物料施入土壤后,T_(1)、T_(2)、T_(3)、T_(4)有机碳损失率分别为64.52%、58.69%、47.04%和29.56%;未损失部分转化为土壤有机质,虽然T_(3)处理有机碳损失率较低,但土壤中的活性有机质占比低于其他处理。T_(3)、T_(4)能降低滩涂盐碱地土壤中的有效态汞、砷、镉、铅、铬含量,其中以T_(4)效果最好,T_(1)、T_(2)处理能降低汞、镉、铬有效态含量,但在一定程度上分别增加有效态砷、有效态铅含量。T_(1)~T_(4)对水稻有效穗、穗粒数有显著提高作用,较对照分别增产10.17%、14.03%、6.65%和24.52%,其中T_(4)能显著增加水稻穗粒数。由此可见,在滩涂盐碱地综合改良利用中,生物腐植酸在有机碳损失率、增加土壤活性有机质、降低土壤重金属含量及提高水稻产量方面具有较显著优势,是滩涂盐碱地改良的优良有机物料投入品。

Influence of light absorption on the metallic nanotextured reflectors of GaN-based light emitting diodes

Metallic nanotextured reflectors have been widely used in light emitting diodes(LEDs) to enhance the light extraction efficiency. However, the light absorption loss for the metallic reflectors with nanotexture structure is often neglected. Here, the influence of absorption loss of metallic nanotextured reflectors on the LED optoelectronic properties were studied. Two commonly used metal reflectors Ag and Al were applied to green GaN-based LEDs. By applying a Ag nanotextured reflector, the light output power of the LEDs was enhanced by 78% due to the improved light extraction. For an Al nanotextured reflector, however,only a 6% enhancement of the light output power was achieved. By analyzing the metal absorption using finite-difference timedomain(FDTD) and the metal reflectivity spectrum, it is shown that the surface plasmon(SP) intrinsic absorption of metallic reflectors with nanotexture structure play an important role. This finding will aid the design of the high-performance metal nanotextured reflectors and optoelectronics devices.

Investigation of Loss Weight and Densification of SiC-Al_2O_3-Y_2O_3 Ceramic Composite on Sintering

α-SiC, Al_2O_3 and Y_2O_3 powders were all used as raw materials. The SiC-Al_2O_3-Y_2O_3 ceramic composites were made by pressureless liquid phase sintering technology. The effects of sintering temperature, loss weight and coordination number on sintering densification were studied. The reason for producing loss weight on sintering was analysed. The results show that the primary reason for producing loss weight on sintering in SiC-Al_2O_3-Y_2O_3 ceramic composite was that chemical reactions between SiC and Al_2O_3 are happened during sintering, and given out volatile gases. If sintering temperature is excessively lower, grain size would be finer, and coordination number would be higher, well then material would be on no sintering densification. If sintering temperature is excessively higher, grains would grow up, though small coordination number would benefit to make pore eliminate and shrink, but coarse microstructure would also block gliding and resetting of grains, together affected by expansion stress from volatile gas, the material densification would instead go down. Only under the sintering process of 1850 ℃ for 30 min, material densification is better, and the mechanical property of ceramic composites is also improved.

Monte Carlo simulation of incident electrons passing through thin metal layer

A Monte Carlo simulation using two schemes,the discrete energy loss approach and the continuous slowing down approximation,was implemented in C++ to calculate the energy transmission coefficient and average energy loss for low-energy(1–10 keV) incident electrons passing through a thin metal layer.The simulation model uses the Ashley model for electron inelastic scattering,the electron elastic scattering cross section taken from the NIST database,and the stopping power derived from the full Penn algorithm.The results of the two schemes agree well with each other and can be used to quantitatively evaluate the shielding effect of a thin coated metal layer on incident electrons for a diamond amplified photocathode.

The study of metal cycles in China

A model of Fe-flow in the life cycle of steel product was put forward and analyzed. Three important resource and environmental indicators for Fe-flow analysis,that is,steel scrap index,iron ore index and iron loss index were derived from this model. Illustrative examples,demonstrating the influence of the variation of steel output on steel scrap index and iron ore index were given. Case studies for estimating the values of steel scrap index of Japan,China and USA in the period of 1988-1997 were carried out. It was clarified that the main reason of severe deficiency in steel scraps for China's steel industry was its continued rapid growth. The study of iron,copper,zinc and lead cycle in China was carried out successfully according to this model.

面向金属丝包芯纱的低落纤喷气涡流纺纱喷嘴设计及其纱线质量

为减少纺纱过程中纤维的损失,改善金属丝包芯纱质量,设计了一种设有负压抽吸锭子的新型低落纤喷气涡流纺纱喷嘴,对其各主要部件的制作工艺和降低落纤的原理进行了阐述。通过实验研究了抽吸孔轴向间距和抽吸孔周向列数对纤维损失和纱线断裂强度的影响。结果表明,在锭子内引纱通道壁面设置抽吸孔有利于减少纤维损失,提高纱线断裂强度。当轴向孔间距从2mm减小到1mm时,纤维损失和纱线强度均显著降低。当抽吸孔周向列数从2列增加为4列时,纤维损失和纱线断裂强度均显著降低,而当周向列数从3列增加至4列时,纱线断裂强度变化不明显。证实了在锭子内引纱通道壁面设置抽吸孔对实现低落纤喷气涡流纺纱和提高纱线质量的可行性,也为喷气涡流纺纱喷嘴装置的改进和发展提供一种新思路。

铁-球墨系金属抗铝热熔损性能及腐蚀机理研究

以经孕育/球化处理、石墨球密度数可调的铁-球墨系金属为研究对象,借助扫描电子显微镜、超声热熔损失重等分析手段,系统研究了不同球墨密度对铁-球墨系金属热熔损性能的影响规律。结果表明,随着球墨密度的增大,铁-球墨系金属热熔损失质量逐渐下降,铁-球墨系金属的抗铝液腐蚀性能与H13钢相比有明显的提升。铁-球墨系金属浸铝热熔损试验后,Fe-Al反应生成物层的厚度与球墨密度成反比,间距小、大比表面积的石墨球阻碍铝液与基体接触和铝液的扩散,从而抑制熔融铝液对基体的腐蚀。铁-球墨系金属表现出更优异的抗铝熔体腐蚀性能。

X70管线钢在酸性和近中性模拟海水溶液中的腐蚀行为

为对比X70管线钢在酸性(pH=3)和近中性(pH=7.7)模拟海水溶液中的腐蚀机制,采用极化曲线,通过电化学阻抗谱(EIS)和腐蚀失重实验对X70管线钢在不同模拟海水溶液中的腐蚀行为进行了研究。结果表明,X70管线钢在酸性溶液中浸泡168 h后腐蚀失重约为近中性模拟海水溶液中的16倍,大部分表面发生均匀腐蚀,局部形成以夹杂物为中心的腐蚀圆环,随着浸泡时间的延长,容抗弧半径和低频区阻抗值|Z|均呈增大趋势,先发生吸附而后出现微弱的扩散,电荷转移电阻Rct值增大,腐蚀速率减小;近中性模拟海水中形成较厚的腐蚀产物膜,氯离子聚集破坏形成小点蚀坑,局部聚集形成大的点蚀,电荷转移电阻减小,腐蚀速率增大,而后趋于稳定;X70管线钢在模拟海水溶液中处于活性溶解状态,与酸性海水溶液相比,管线钢在近中性模拟溶液中自腐蚀电位Ecorr正移137 mV,自腐蚀电流密度icorr为酸性海水溶液中的0.047倍。因此,X70管线钢在酸性模拟海水溶液中的腐蚀规律可为其应用于海底管线的腐蚀控制提供理论支撑,对其安全服役具有十分重要的意义。

某输气管道漏磁内检测金属损失缺陷验证检测及评价

某输气管道在首次漏磁内检测时发现2处大于20%WT(Wall Thickness,壁厚)的管道本体缺陷,对缺陷开展了基于内检测数据的开挖验证及检测,并将实测结果和内检测报告结果进行比对来验证内检测器性能规格。结果显示:内检测报告的金属损失缺陷深度比实测值偏小,但在可信度为90%的精度范围内;报告的缺陷长度、宽度及周向定位与实测值间存在偶然性偏差,需进一步扩大开挖验证。采用ASME B31G标准对2处缺陷进行适用性评价,结果表明管道估计维修因子(ERF)均小于1,满足承压能力要求,无须立即修复。

从锌冶炼废渣提取锗和锌金属的最佳工艺参数的研究

以四川西昌某锌冶金企业稀贵金属综合回收系统一段浸出液为原料,通过丹宁沉锗法,对影响沉锗率和锌损失率的条件进行试验。试验结果表明丹宁酸加入量为浸出液即沉锗前液锗含量的25倍时,酸度控制在PH值2.5,温度控制在60℃~70℃,搅拌时间为25min时,可达到97%的沉锗率(以液计),并能将锌损失率控制在11%左右。