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Dealcoholization temperature markedly influences the surface area and porosity of the resultant MAO-supports. When the support was pretreated at lower or higher temperature, the corresponding MAO-support shows very low surface area; 2.XRD and IR analyses indicate that MAO has reacted with the residual ethanol in the supports, which is an important manner to get MAO fixed on the carrier. Morever, XPS analyse indicates that MAO can also be coordinated with MgCl_2, which is another way to get MAO fixed on the support; 3.ICP and EDX analyses indicate that dealcoholization temperature not only determined the element content on the solid catalyst, but also influences the element distribution on the carrier; 4.The activities of the supported phenoxy-imine catalysts and the properties of resultant polymers are strongly dependent on the dealcoholization temperature. The support (MSP-5) obtained by treating MgCl_2·2.56C_2H_5OH at 160℃for 4 h, then modified by MAO is very effective for immobilizing complex 3, the resultant solid catalyst (MSPC-5) shows very high activity in ethylene polymerization, and its kinetics of polymerization is stable during the reaction process. Finally, PEs with spherical morphology and high bulk density (over 0.35g/ml) were obtained, without reactor fouling; 5.In this work, polymerization conditions such as alkylaluminums, Al/Zr ratio, temperature and H_2 had a pronounced effect on the activity of MSPC-5 and properties of PE;(3). New MgCl_2-Supported Single-Site Catalysts for Ethylene Polymerization In this work, a kind of new MgCl_2 support was obtained by anhydrous MgCl_2 co-milled with solid MAO, and it is a creative contribution. Then some single-site catalysts were supported on the new MgCl_2 support, and the resulted solid catalysts were tested in ethylene polymerization, the results indicated that: 1.XRD and IR analyses indicate that MAO does be coordinated with MgCl_2, which is in good agreement with the results obtained by XPS; 2.co-mlling time had no obvious effect on the texture of support after 12 hours; 3.In this work, MgCl_2 was co-milled with solid MAO for different hours, and then complex 3 was supported on these co-milled supports. It was found that co-milling time markedly influences the activity of solid catalysts, but it had negligible effect on the kinetic profile and the properties of resultant PE.
XPS研究结果表明,MAO不仅仅只和乙醇作用,MAO还与MgCl_2本身有一定的作用,这是一个极为重要的发现; 3、通过ICP和EDX表征,发现载体的脱醇温度直接影响着元素在固体催化剂中的含量及分布; 4、脱醇温度极大地影响着负载苯氧基亚胺类催化剂的活性和聚合物的性能,特别是原始载体经160℃活化4小时制备得到的固体催化剂MSPC-5的活性明显高于其他脱醇温度条件下制得的固体催化,并且催化剂寿命长,表现出稳定的动力学行为,最终获得了高堆密度(大于0.35g/ml)的球形聚乙烯颗粒; 5、本文选择MSPC-5为研究对象,考察了聚合反应参数对催化剂的活性及其聚合物的影响,研究发现:不同的烷基铝对催化剂具有非常重要的影响,特别足TIBA对MSPC-5的助催化活性最高,烷基铝的加入量有一个较佳值,聚合温度为80度时活性最高,H_2的加入使催化剂的活性明显降低且聚合物的分子量也减小;、新型氯化镁载体负载单活性中心催化剂催化乙烯聚合本文创造性采用固体MAO与无水氯化镁直接进行共研磨,制备出了一种的新型的氯化镁载体,并将该载体用于多种单活性中心催化剂的负载化研究,研究表明: 1、通过BET、XRD的表征,再次证实了MAO与MgCl_2之间具有直接作用,与XPS的研究结果相一致; 2、当研磨时间高于12小时时,延长研磨时间对载体的结构没有显著的影响; 3、将配合物3负载于共研磨时间不同的一系列载体上,乙烯聚合结果表明,尽管共研磨时间对负载催化剂的活性具有明显的影响,但是它对聚合物的性能以及催化剂的影响不明显。
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To obtain precise result, itis necessary, in the aspect of hardware, to set up one stable optics system with highSNR, only if so, can we do the measurement with the steady NIR. To do so, we designthe optics system using AOTF, and take some measures to increase the light energyand the system SNR, which includes the three layers structure of the light chamber,the equipments to cover the useless light, polarizing to reduce the influence of 0 gradelight and focalize the light with lens. Apart from the hardware aspect, according to theexperiments, we can see that the different temperatures between at setting up themodels and at predicting the results will affect the prediction results in a way, and theaffection extent will be increased along with the increase of the temperaturedifference. Moreover, the light energy that can be detected will be different with thecontact pressure, and the match of the refractive indexes between the tissue and thesurroundings will enhance the light transmission depth, which will take moreinformation of the tissue. So, during the measurement, we should ensure the sametemperature between measuring and predicting, the same contact pressure at everymeasurement and the match of the indexes between the tissue and the surroundings aspossible as we can.
要提高测量精度,从硬件方面就必须有一个稳定的、信噪比较高的分光光路系统,以此得到稳定的近红外光来进行无创检测,针对这个目的,我们设计了 AOTF 分光光路系统,并在系统中采用一定的措施如三层灯室结构、遮光筒以减小杂散光、起偏和检偏来减小 0 级光影响、透镜汇聚等等来提高出射光的能量和系统的信噪比;从其他影响因素方面,通过实验,我们得到不同的建模温度对于预测结果有一定的影响,且影响随着温度的差值越大而越大,另外散反射光谱的能量也随着接触压力的不同而不同,组织的折射率与环境匹配将加大光的入射深度,从而能携带更多的组织信息,所以在测量时我们尽可能保证同一温度、保证同一接触压力以及利用物理或者化学的方法使组织与环境折射率匹配等。
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The paper investigates both block-type pilot linear minimum mean square error algorithm and IEEE802.16 OFDM channel estimation analysis. Simulation results confirm the block-type pilot structure is more suitable for IEEE802.16 system. An optimal pilot setting algorithm, based on space frequency domain, is explored and the pilot chart is presented. The proposed algorithm finds its application in MIMO-OFDM. Simulation results show the algorithm presents a good approximation to the perfect channel state information curve, with about 2dB difference in SNR. The simulation results also demonstrate the algorithm achieves fairly high stability in the environment of fast fading, performance of the proposed algorithm is better that of pilot training channel estimation.3. Taking into account the characteristics of IEEE802.16 OFDM system, OFDM system simulation platform is constructed in Matlab, exploiting simulink as a tool. OFDM modulation and demodulation simulation system are configured on LabVIEW platform. All the system signal processing is simulated, including defining system parameters, designing modulation model, and verifying all the proposed algorithms under different environments, such as white Gaussian noise, multi-path fading, with or without guard interval etc. Bit error performance is evaluated. The research provides valid theoretical basis for practical OFDM system performance evaluation.4. Taking advantage of software radio, the paper designs a hardware platform with both 256-IFFT/FFT and 512-IFFT/FFT OFDM schemes co-existing in one platform. You can predetermine one from the two schemes to carry out almost the same model function with different system performance and parameter setting.5. Referring to IEEE802.16 standard, the paper proposes a design method for generating signals and frames suitable for laboratory investigations implemented in laboratory environment.6. Based on 6701evm digital evaluation card, combined with analogy front-end, the paper designs a DSP software model to deal with baseband signal processing. An overall OFDM scheme, with modulation and demodulation function, is accomplished.
讨论分析了MIMO-OFDM中一种基于空频域的最优导频设置算法,给出了导频图案,通过仿真实验表明,该算法与理想的信道状态信息曲线非常接近,信噪比差距约在2dB左右,并且在快衰落条件下具有较好的稳定性,其性能要优于基于前导训练的信道估计方法。3、根据IEEE802.16OFDM系统特点,论文分别在Matlab中应用Simulink工具构建OFDM系统仿真平台、在LabVIEW平台上实现了OFDM调制解调仿真系统,模拟了整个系统的信号流程,进行了OFDM仿真系统参数的选择和调制模块的仿真设计、论证各算法性能,并根据各种不同的条件:例如高斯噪声、多径衰落、有无保护间隔等,对系统的误码特性进行了评估,为正确评价实际OFDM系统的性能提供了有效的理论依据。4、论文以软件无线电思想作为指导,提出了以256点IFFT/FFT为核心和以512点IFFT/FFT为核心的两种OFDM算法模式并存于同一个硬件平台、且可预选的方案,它们在参数选取和性能指标上有所差异,均实现了相似的模块和功能。5、论文参考IEEE 802.16无线网络标准的参数设置,针对本设计系统的应用环境和系统硬件的性能速率,提出了一种应用于实验室环境的信号结构、帧格式等参数设计。6、论文基于TI公司的6701evm数字评估板卡,结合模拟前端搭建数字中频平台,设计了基带处理的DSP软件模块并进行系统调试,基本实现了一套完整的OFDM调制解调方案。
- 推荐网络例句
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Breath, muscle contraction of the buttocks; arch body, as far as possible to hold his head, right leg straight towards the ceiling (peg-leg knee in order to avoid muscle tension).
呼气,收缩臀部肌肉;拱起身体,尽量抬起头来,右腿伸直朝向天花板(膝微屈,以避免肌肉紧张)。
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The cost of moving grain food products was unchanged from May, but year over year are up 8%.
粮食产品的运输费用与5月份相比没有变化,但却比去年同期高8%。
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However, to get a true quote, you will need to provide detailed personal and financial information.
然而,要让一个真正的引用,你需要提供详细的个人和财务信息。