Oxidation Modification of Polyacrylonitrile-Based Carbon Fiber and Its Electro-Chemical Performance as Marine Electrode for Electric Field Test

A novel sensor for ocean electric field testing has been fabricated by polyacrylonitrile-based on carbon fibers with electro-chemical oxidation.The surface profile characteristics of the carbon fibers were characterized by scanning electron microscope,Fourier transform infrared spectra and contact angle.Cyclic voltammetry and Tafel curves have been used to study its electro-chemical performances.Two identical electrodes in sea water as the electric field sensor will swiftly respond to applied electric field which causes positive and negative ions to move in opposite direction,resulting in a electric potential difference(ΔE).Test result indicates that the offset potential is typically below 1 m V with a drift of 60-170μVd^-1.Typical self noise level is 1.07 nV√Hz^(1/2)@1 Hz.The electric field response indicates that the modified electrode pair shows better response to AC sine signal of amplitude and frequency(5 mV and 1 mHz)respectively than its blank.The electric field response model of the modified electrodes is creatively presented according to its electric double layer capacitance and Faraday pseudo-capacitance.Many advantages of the carbon fiber electric field electrode will make it have potential application prospect.

神经行为学实验Narrow-Alley Test及Corner Test改良:Narrow-Alley Corner Test

目的改良传统的Narrow-alley Test及Corner Test,增强实验的可操作性和结果的可靠性。方法用Narrow-alley Test、Corner Test及改良后的Narrow-alley Corner Test检测三组SD大鼠:脑出血+GCSF治疗组;脑出血+生理盐水安慰治疗组;正常对照组。结果(1)与Narrow-alley Test及Corner Test结果一致,正常大鼠在Narrow-alleyCorner Test实验装置中向左、向右"站立转身"的几率接近,而脑损伤大鼠则趋向沿损伤同侧作"站立转身"。(2)Narrow-alley Corner Test不须反复刺激大鼠,减少了人在实验现场对动物活动的影响,增强了实验的可操作性和结果的可信度。结论Narrow-alley Corner Test是一种可操作性强、结果可靠的神经行为学检测方法。

Test particle simulations of resonant interactions between energetic electrons and discrete, multi-frequency artificial whistler waves in the plasmasphere

Modulated high frequency （HF） heating of the ionosphere provides a feasible means of artificially generating ex- tremely low frequency （ELF）/very low frequency （VLF） whistler waves, which can leak into the inner magnetosphere and contribute to resonant interactions with high energy electrons. Combining the ray tracing method and test particle simulations, we evaluate the effects of energetic electron resonant scattering driven by the discrete, multi-frequency arti- ficially generated ELF/VLF waves. The simulation results indicate a stochastic behavior of electrons and a linear profile of pitch angle and kinetic energy variations averaged over all test electrons. These features are similar to those associated with single-frequency waves. The computed local diffusion coefficients show that, although the momentum diffusion of relativistic electrons due to artificial ELF/VLF whistlers with a nominal amplitude of ~ 1 pT is minor, the pitch angle scattering can be notably efficient at low pitch angles near the loss cone, which supports the feasibility of artificial triggering of multi-frequency ELF/VLF whistler waves for the removal of high energy electrons from the magnetosphere. We also investigate the dependences of diffusion coefficients on the frequency interval （△f） of the discrete, multi-frequency waves. We find that there is a threshold value of Af for which the net diffusion coefficient of multi-frequency whistlers is inversely proportional to △f （proportional to the frequency components Nw） when △f is below the threshold value but it remains unchanged with increasing Af when △f is larger than the threshold value. This is explained as being due to the fact that the resonant scattering effect of broadband waves is the sum of the effects of each frequency in the ＇effective frequency band＇. Our results suggest that the modulation frequency of HF heating of the ionosphere can be appropriately selected with reasonable frequency intervals so that better performance of controlled precipitation of high energy electrons in the plasmasphere by artificial ELF/VLF whistler waves can be achieved.

Study on the Treatment of Acid Mine Drainage Containing Fe^(2+) and Mn^(2+) Using Modified Spontaneous Combustion Gangue

The high concentrations of Fe^(2+) and Mn^(2+) in acid mine drainage make it difficult and expensive to treat.It is urgent that we find a cheap and efficient adsorption material to treat Fe^(2+) and Mn^(2+).As a solid waste in mining areas,coal gangue occupies a large area and pollutes the surrounding environment during the stacking process.Developing a method of resource utilization is thus a research hotspot.In this study,we modified spontaneous combustion gangue using NaOH,NaCl,and HCl by chemically modifying the minerals.We determined the optimal conditions for treating Fe^(2+) and Mn^(2+) in acid mine drainage with spontaneous combustion gangue and modified coal gangue using the single factor test method.Based on results of the static test,two dynamic test columns,column No.1(spontaneous combustion gangue)and column No.2(NaOH modified spontaneous combustion gangue),were constructed,and the repair effects of acid mine drainage were compared and analyzed using dynamic experiments.The results show that overall,NaOH modified spontaneous combustion gangue is the most efficient at removing the Fe^(2+) and Mn^(2+) in acid mine drainage.The optimal conditions for NaOH modification are an NaOH concentration of 3 mol/L,a liquid to solid ratio of 2 L/kg,and a modification time of 8 h.The overall efficiency of column No.2 at removing Fe^(2+) and Mn^(2+) from acid mine drainage is better than that of column No.1.Among them,the average removal efficiency of Fe^(2+)and Mn^(2+) from acid mine drainage in column No.2 were 97.73%and 44.82%,respectively.The above results show that NaOH modified spontaneous combustion gangue is a good adsorbent,which has application potential in wastewater remediation,as it can achieve the purpose of“treating dust with waste”.

Modification Effect of P+Sr+Ce Compound on Microstructure and Properties of Cast High Silicon Heat-Resist Aluminum Alloy

The P ＋ Sr ＋ Ce compound modification technologies of as-cast Al-21Si-1.5Cu-1.5Ni- 2.5Fe- 0.5Mg alloy were investigated by means of orthogonal test. Orthogonal test results show that 3% （CaH2PO4 ＋ 2CASO4）＋ 0.2%Sr ＋ 0.2%Ce is the optimum additive of modification treatment which can fine eutectic and primary silicon also can change the form of rich-iron phase at same time. The needle form of rich-iron phase is Al9FeSi3, which is prored by X-ray diffraction analysis and X-ray energy spectrum analysis. After compound modification treatment, the needle form of rich-iron phase disappeared and the fish bone form of rich-iron and rich-Ce phase that is AlsCeFe emerged. Both at room temperature and at 300℃, the tensile strength of the alloy after the modification treatment with the optimum additive is 30% lager than that of the alloy unmodified. Observed by SEM, the brittle intercrystalline tensile fracture changed into a blended one in which has many dimples.

An Energy Absorber with Force Modificator

Thin-walled tubes are extensively applied in engineering, especially in vehicle structures to resist axial or traversal impact loads, for their excellent energy absorbing capacity. However, in the axial deformation mode, the force history has an extremely high peak force which may bring not only fatal injury to occupants but also damage to structures, cargo and environment. Aiming to develop energy absorbers with impact-force modificator, square metal tube with force modificator is investigated which can monitor the force-deformation history of the tube. A small device is designed to serve as an impact-force modificator, which introduces desired imperfections to the square tube just before the impact happens between the impactor and the tube, so as to reduce the peak force. Prototypes with various governing parameters were manufactured and tested both quasi-statically and dynamically to study the effects of these parameters on the characteristics of energy absorption. The results show that the force modificator can achieve the desired reduction of the peak force well whilst remaining the specific energy absorption capacity of the original square tube. With future improvements, it could be applied to vehicles or roadside safety hardware to mitigate the consequences produced by traffic accidents.

Fault Waveform Regenerator and Its Digital Closed-Loop Modification Technique

In order to provide a novel and more effective alternative to the commonly used relay protection testing device that outputs only the sinusoidal testing signals, the concept of fault waveform regenerator is proposed in this paper, together with its hardware structure and software flow chart. Fault waveform regenerator mainly depends on its power amplifiers (PAs) to regenerate the fault waveforms recorded by digital fault recorder (DFR). To counteract the PA’s inherent nonlinear distortions, a digital closed-loop modification technique that is different from the predistortion technique is conceived. And the experimental results verify the effectiveness of the fault waveform regenerator based on the digital closed-loop modification technique.

The Role of the American Oil Chemists’Society in World Trade——Quality Assurance Testing,Certified Reference Materials,and International Liaison Activities

The American Oil Chemists’ Society(AOCS) is a volunteer-led association. AOCS develops and publishes methods of analysis for fats, oils, proteins, surfactants, and related materials according to accepted international standards to ensure equitable trade practices on a global scale. AOCS Official Method development has been going on for over a hundred years. The founding vision of AOCS in 1909 was "an organization designed for the development and advancement of analytical methods for cottonseed products." AOCS Official Methods are essential to world trade and are used to confirm the value of billions of pounds of oilseed-based commodities and finished products each year. In addition, AOCS conducts proficiency testing, provides certified reference materials, and collaborates with other standards developers including the International Organization for Standardization(ISO) and the Codex Alimentarius Commission. AOCS serves as a professional scientific membership organization providing current and emerging information as well as disseminating research results in oils, fats, lipids, proteins, surfactants, and related materials. Several avenues are used, especially meetings, publications, interest groups, networking opportunities, and web presence. Many scientists, experts, and others engaged in working in these fields find their professional "home" in AOCS. The AOCS Technical Leadership Committee comprises some of the most experienced AOCS members and scientists. The AOCS Technical Services department staff relies on this committee for guidance on scientific matters and for advice in prioritizing the opportunities facing AOCS.

曲面综合法少齿数弧齿锥齿轮加工参数计算仿真与切齿试验

少齿数高减比齿轮传动具有体积小和轻量化的优势。根据综合变位和节锥外啮合原理,设计了一对高减速比弧线等高齿锥齿轮,给出了相关的几何限制条件,推导了大、小轮齿面方程。大轮采用成形法加工,小轮采用单面展成法加工,为弥补大轮齿廓曲率的不足,小轮刀齿采用圆弧刃修形,采用曲面综合法优化求解了小轮加工参数;通过建立ease-off差齿面,对齿面修形梯度、传动误差、接触路径与接触线进行了仿真。切齿和滚检试验,验证了高减比弧齿锥齿轮几何设计、刀盘修形加工方法的可行性。

聚丙烯改性及抗老化综述

聚丙烯(PP)由于具有价格低廉且性能较好的特点,成为应用范围最广泛的通用塑料之一,但是,由于其分子链结构中包含的叔碳原子极易在氧气、热、紫外线的条件下产生热氧老化降解及光老化降解,使聚丙烯表现出较差的抗老化性能,当处于室外时,其使用寿命严重缩短,限制了其应用范围。主要介绍了聚丙烯改性的方法,例如,接枝改性、熔融共混改性和改变晶体结构等,分析了聚丙烯的老化机理以及老化的过程,综述了近年来国内外关于聚丙烯改性及抗老化的方法,对聚丙烯的发展进行展望。

糠醇浸渍速生人工林木材的干燥特性研究

木材浸渍改性商业应用的主要技术难点之一是二次干燥速度慢、易开裂、易变形。本文以杨木和杉木为研究对象,使用浓度为30%和50%的糠醇水溶液对其进行浸渍改性,再以百度干燥法分析糠醇浸渍材的干燥特性,辅以干缩试验和剖面密度(VDP)试验探究干燥缺陷成因。结果表明:50%浓度浸渍材的干燥缺陷等级均大于30%浓度浸渍材,杨木浸渍材的等级均高于杉木浸渍材;杉木30%和50%浓度浸渍材百度干燥平均时间分别为24 h和29 h,而杨木30%和50%浓度浸渍材分别为20 h和30 h。浸渍材不同位置的干缩系数存在显著差异,浸渍后密度分布更加不均匀。杉木和杨木糠醇浸渍材二次干燥困难的主要原因为固化的糠醇堵塞了水分内部迁移通道,从而使干燥速度降低;糠醇分布不均匀导致干缩系数差异进一步加大,处理材易开裂、易变形。

双等离子体改性超高分子量聚乙烯复合材料的弹道响应

为揭示双等离子体改性对超高分子量聚乙烯(UHMWPE)复合材料冲击性能的影响,采用真空辅助树脂灌注成型技术(VARI)制成UHMWPE复合材料,借助原子力显微镜等手段对改性前后的纤维表面进行观测,探究复合材料在低速及高速冲击时的抗冲击性能以及防弹机制。低速冲击载荷作为响应值构筑响应曲面模型,高速摄影机捕捉子弹侵彻改性前后复合材料的过程,分析板材的吸能情况并对侵彻后的试样进行表面观测。结果表明:未改性板材通过各层振荡式波动以形成严重分层来耗散能量;改性后的材料能有效地包覆住子弹,背弹面表层纤维呈现原纤化,断口处出现树脂大量富集,阻抗作用增强,吸能值较未改性材料提高45.59%。

某心墙坝土料分散性判别与石灰改性土的性能规律分析

分散性土作黏土心墙会影响大坝的防渗安全,通过针孔试验、碎块试验对新疆某心墙土料的分散性进行了判别,分别采用天然河水与石灰进行改性试验,研究不同石灰掺量和陈化时间对改性土物理、力学性能的影响规律。结果表明,黏粒含量为12%是土料产生物理性、化学性分散的界限;采用天然河水进行改性,效果不佳,当石灰掺量为3%时,可完全消除分散性;土样掺入1%的石灰后,界限含水率变化明显,最大干密度由1.79 g/cm3降至1.69 g/cm3、压缩模量由13.4 MPa增至19.4 MPa、黏聚力由25.1 kPa升至43.3 kPa;随石灰掺量的增加,最大干密度提高、内摩擦角减小,黏聚力增大;随着陈化时间的延长,液限呈增长趋势,最大干密度在24 h内较稳定,之后开始降低,240 h后趋于稳定,压缩性在72 h内变化不明显,而后开始增强。由于石灰中含有大量的钙离子,因此使分散性土的性能发生变化。

基于化学分散机制理论对分散性土的改性试验研究

分散性土在中国西北、东北地区分布广泛,受环境限制许多新建水利水电工程不得不选择分散性土作为坝体心墙的防渗土料,由于它的抗冲蚀能力很低,容易造成堤坝管涌、路基失稳等现象,因此如何改善其分散性成为了当下水利水电工程建设中亟待解决的问题。为了探明分散性土改性效果及作用机理,基于化学分散机制理论,对西藏地区某水利工程的分散性防渗土料分别进行了掺配MgO、CaO、MgCl_(2)、CaCl_(2)4种改性剂的改性试验研究,掺配含量范围为0.15%~1.50%。结果表明:各含量的MgO基本不具备改性功能,当CaO、MgCl_(2)、CaCl_(2)3种改性材料掺量达1%后,针孔试验、碎块试验、孔隙水阳离子试验结果均显示为非分散性土,改性效果较好。综合考虑现场施工的可操作性、经济性及对土体性质结构的影响等因素,建议现场采用掺量1%的MgCl_(2)对分散性防渗土料进行改性处理。

内蒙古阴山南麓地区生土砌体材料改性研究

在内蒙古阴山南麓地区的生土中掺入莜麦秸秆、羊毛纤维、糯米浆以及甲基硅酸钠,通过正交试验对生土材料进行复合改性,研究不同掺量下各改性材料对改性生土试件抗压强度、导热性能的影响规律,并确定最优配合比。结果表明,高抗压型改性生土材料最优配合比为:整体含水率18%,莜麦秸秆掺量为0.6%,羊毛纤维掺量为0.6%,糯米浆掺量为2%,甲基硅酸钠掺量为1.5%。相较于素土试件其抗压强度提高了65.6%,导热系数减少了8.0%。低导热型最优配合比为:整体含水率18%,莜麦秸秆掺量为0.6%,羊毛纤维掺量为0.6%,糯米浆掺量为2%,甲基硅酸钠掺量为0.7%。相较于素土试件其抗压强度提高了50.5%,导热系数减少了16.6%。

静力模型优化分析简支T梁桥横向分布系数与刚度

鉴于桥梁荷载试验成本高且对试验人员专业性要求较高,为了能为桥梁监测提供更为贴合实况的理论数据,提出一种基于结构静力学试验测试结果修正理论参数的方法。该方法能考虑T梁间的剪切变形,比铰接T梁法更贴合梁间实际联系状况,提高了分析精度,降低了对试验人员专业性要求,并将该方法应用于有机玻璃铰接T梁桥模型的横向分布系数与刚度分析。结果表明:不考虑梁间剪力影响,在简化分析模型分析计算下,荷载横向分布影响线的计算结果与铰接T梁法一致,确保了所提简化模型与分析结果的准确性;该方法得到的荷载横向分布系数与实况契合度优于铰接T梁法,更能准确反映桥梁实际刚度;以有机玻璃模型静力实测响应值为基准,识别简化分析模型的关键控制参数,基于实测数据、修正后的理论模型及采用软件提取值计算得到的横向分布系数差异性较小,从而证实该方法能更好地反应桥梁实际刚度,为桥梁监测提供更为贴合实况的理论数据。可见静力模型优化分析简支T梁桥,在最不利荷载作用下的梁体下挠量优化率达27.71%,在3种工况下,下挠量最大梁体影响线数值优化率分别达到34.82%、13.07%和5.46%。

核电厂一回路水压试验策略变更的风险研究

国家核安全局发布技术政策,推动国内执行RES-M在役检查要求的核电机组实施一回路水压试验策略调整。本文通过对比研究一回路水压试验与替代试验的差别,提出了一种定量评估一回路水压试验策略调整的风险分析方法,并以某执行RES-M体系要求的核电机组一回路水压试验策略调整为例,分析该核电机组一回路水压试验策略调整的风险。分析结果表明,该核电机组一回路水压试验策略调整后的风险增量较小,满足风险可接受准则。本文研究成果对国内执行RES-M体系的核电机组一回路水压试验策略调整的安全风险分析具有重要借鉴意义。

不同种类重质碳酸钙在不饱和聚酯家具白底漆中的应用对比研究

研究了不同种类原矿碳酸钙的纯度、表面改性等对不饱和聚酯家具白底漆光泽度、打磨性、防沉性等各项性能的影响。结果显示,以白云石和大理石为原矿生产的重质碳酸钙,其在不饱和聚酯家具白底漆中的光泽度较高,但打磨性能较差,且容易产生硬沉淀,不宜应用在该体系中;而以方解石和大理石为原矿生产的重质碳酸钙,其打磨性能和防沉性能明显优于白云石和大理石原矿产品;采用硬脂酸改性后的重质碳酸钙,其光泽度、防沉性能、打磨性等指标均比未作处理的原粉性能好。

模型建构活动的检验与修正

通过种群增长模型和能量流动模型两个案例,展示了如何通过持续的检验和修正来促进模型的逐步发展。强调了在建模过程中需要进行分析、评价和创造性思维等高阶思维活动,并提出了改进教学设计的建议,以促进学生批判性思维和创造性思维的发展。

环氧型扩链剂中环氧当量的定量方法改性研究

基于市面上对环氧型扩链剂中环氧当量的测定方法无统一标准,本文依据现行国家标准GB/T 4612-2008《塑料环氧化合物环氧当量的测定》,对不同厂家环氧型扩链剂中环氧当量的测定方法进行了深入的研究和探索,对其测定方法中不同试剂的用量等关键步骤进行了讨论和优化,形成了一套适用于环氧型扩链剂中环氧当量的测定方法。此方法操作简便、分析速度快,且对样品溶液要求不高,非常适合工厂、车间等在生产上对产品进行质量控制。