音频处理器在广播上星中的应用

为了更好地利用卫星转发器的带宽资源,解决广播信号传输的问题,自１９９４年,山东电视台地球站利用ＮＩＣＡＭ－７２８系统,将山东人民广播电台和山东经济广播电台的两套广播节目与山东电视台节目一起送上卫星,较好地解决了这两个频道信号覆盖全省的问题。　　　　　１电视、广播一起上星　　　　带来的问题　　　　　我国的电视制式为ＰＡＬ　Ｄ,在卫星电视广播中,视频信号为０～６ＭＨｚ,实际占用带宽８ＭＨｚ,伴音载波为６．５ＭＨｚ,为了在不改变原视频、电视伴音的前提下传输两路广播信号,采用７．２８ＭＨｚ副载波调制广播…     

弯管结构塑性极限分析的数值方法及应用

从塑性极限分析数值计算的角度,分析了多组载荷联合作用下弯管结构的塑性极限承载能力。为了克服塑性极限上限分析中目标函数非线性非光滑所导致的数值困难,提出了一种弯管结构塑性极限上限分析的无搜索优化迭代算法;采用一种改进的弯管单元并利用加载路径的径向射求解方案处理多组载荷系统。通过对典型弯管结构进行塑性极限分析得出了一些有价值的结论。     

Designable assembly of atomically precise Al4O4 cubane supported mesoporous heterometallic architectures

Heterometallic cluster-based framework materials are of interest in terms of both their porous structures and multi-metallic reactivity. However, such materials have not yet been extensively investigated because of difficulties in their synthesis and structural characterization. Herein, we reported the designable synthesis of atomically precise heterometallic cluster-based framework compounds and their application as catalysts in aldol reactions. By using the synergistic coordination protocol, we successfully isolated a broad range of compounds with the general formula, [Al₄M₄O₄(L)₁₂(DABCO)₂] (L = carboxylates; DABCO = 1,4-diazabicyclo[2.2.2]-octane; M²⁺ = Co²⁺, Mn²⁺, Zn²⁺, Fe²⁺, Cd²⁺). The basic heterometallic building blocks contain unprecedented main-group γ-alumina moieties and surrounding unsaturated transition metal centers. Interestingly, the porosity and interpenetration of these frameworks can be rationally regulated through the unprecedented strategy of increment of the metal radius in addition to general introduction of sterically bulky groups on the ligand. Furthermore, these porous materials are effective catalysts for aldol reactions. This work provides a catalytic molecular model platform with accurate molecular bonding between the supporters and catalytically active metal ions.

Mesoporous heterometallic architectures are designed by the incorporation of the Al₄O₄ cubane and interpenetration regulation.     

超载下桩锚支护基坑安全系数的计算分析

假设桩锚支护下基坑土体塑性变形破坏机构以及满足边界条件的合理机 动场,而不是传统方法中那样将土体离散为许多相对运动的刚性块. 运用土塑性力学中 极限分析法的上限定理从能量功率角度探讨了超载下桩锚支护基坑竖直边坡安全系数的计算 方法. 并以一工程为例,用FLAC数值分析软件的模拟结果对该方法进行了验证.     

大孔树脂对红霉素的吸附动力学研究

利用大孔吸附树脂Amberlite XAD16及HZ816对红霉素的吸附动力学实验,研究了温度、初始浓度、溶液pH值及搅拌速度等因素对吸附过程的影响.结果表明,Amberlite XAD16及HZ816对红霉素的吸附速率符合一级吸附动力学方程及颗粒内扩散方程,过程受液膜扩散阻力及颗粒内扩散阻力共同影响.同时,表观吸附速率常数与颗粒内扩散速率常数均随着温度的升高而增大,随着初始浓度的增大而增大,随着溶液pH值增大而增大,随着搅拌速度加快而增大.     

Tuning Internal Strain in Metal–Organic Frameworks via Vapor Phase Infiltration for CO2 Reduction

A gas-phase approach to form Zn coordination sites on metal–organic frameworks (MOFs) by vapor-phase infiltration (VPI) was developed. Compared to Zn sites synthesized by the solution-phase method, VPI samples revealed approximately 2.8 % internal strain. Faradaic efficiency towards conversion of CO₂ to CO was enhanced by up to a factor of four, and the initial potential was positively shifted by 200–300 mV. Using element-specific X-ray absorption spectroscopy, the local coordination environment of the Zn center was determined to have square-pyramidal geometry with four Zn−N bonds in the equatorial plane and one Zn-OH₂ bond in the axial plane. The fine-tuned internal strain was further supported by monitoring changes in XRD and UV/Visible absorption spectra across a range of infiltration cycles. The ability to use internal strain to increase catalytic activity of MOFs suggests that applying this strategy will enhance intrinsic catalytic capabilities of a variety of porous materials.     

LED光诱导下咪唑并吡啶氰甲基化反应用于本科实验教学的探索

可见光催化的有机反应具有高效、条件温和、操作简单、催化剂用量少等优点,近年来受到广泛关注。以咪唑[1,2-a]吡啶杂环为骨架的化合物表现出丰富多样的生物活性,如抗炎、抗病毒活性、抗原生虫药、细胞周期蛋白依赖性激酶抑制剂等。3-氰甲基-2-苯基咪唑并[1,2-a]吡啶是合成具有抗抑郁作用的药物唑吡坦的关键中间体。我们在前期的研究工作中,以2-苯基咪唑并[1,2-a]吡啶和溴乙腈为原料,通过可见光诱导,在光催化剂fac-Ir(ppy)3的作用下,合成了3-氰甲基-2-苯基咪唑并[1,2-a]吡啶。本文以此反应为基础,通过将可见光催化这一新型的方法运用于本科实验教学,拓宽本科生的视野,增加其对有机化学实验的兴趣,并掌握微量化学实验的基本操作和相关仪器的使用方法。本设计实验使用LED灯作为光源,避免了剧毒试剂的使用,符合绿色化学理念,具备制备方法简单、生产成本低、产物收率高、重复性良好等优点。     

半导体器件工艺中热电偶可靠性测温

本文介绍了半导体器件工艺中利用热电偶测温的原理、性能以及如何对热电偶误差进行修正补偿。     

用飞秒激光脉冲研究聚合物膜中PbS超微粒的非线性光学性质

将ＰｂＳ超微粒掺进有机物中得到ＰｂＳ／Ｆｌｅｍｉｏｎ复合膜。室温下的线性吸收光谱表明其吸收带边与体相材料相比发生明显兰移，但没有观察到激子吸收峰。用飞秒激光脉冲做光源，用泵浦－探测方法记录了样品的时间分辨光克尔效应信号，据此得到其三阶非线性极化率、响应时间等一些重要数据，并对观察到的实验现象进行了分析讨论。